Kite Strings

The following is a transcription of the text of the 47 issues of Donnell Hewett's Skyting newsletter series which he typed, photocopied, and mailed around the world from 1981/10 to 1986/10.

Any misspelled word which would have been picked up by a spellchecker is almost certainly as it appeared in the original text.

Caution: The Surgeon General has determined that reading this material and implementing any of the theory, procedures, and equipment explained and described herein may - and very likely will - be extremely hazardous to your health.

To understand why and/or participate in the discussion please go to:

http://www.kitestrings.org/topic54.html

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1981/10
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SKYTING NO. 1
October 1981
$2.00
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1981/10-01

Dedicated to the open exchange of ideas and information concerning skyting and its associated activities.
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1981/10-02

SKYTING magazine is published periodically as information becomes available, by Donnell Hewett, 315 N. Wanda, Kingsville, TX 78363; telephone (512) 592-6757. Price is $2.00 per single copy or $10.00 for six (6) copies. Requests for copies should specify how many copies of which issues are to be sent. Subscription requests should tell which issue begins the subscription.

Contributions of news, notes, articles, and illustrations are sincerely appreciated. Such contributions need to be typed clearly in columns of width 3.5 inches with line illustrations camera ready for photocopy reduction to 0.7 of their original size. All requests for return of material must be in writing and a self-addressed stamped envelope enclosed. Items accepted for publication cannot be returned since they will be cut up, rearranged, and pasted on the master page forms of the magazine. Notification is required if contribution has been submitted to other publications. SKYTING magazine reserves the right to edit contributions where necessary. Neither SKYTING magazine nor its publisher assume responsibility for the material or opinions of its contributors.
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1981/10-03

Copyright 1981
SKYTING
ALL RIGHTS RESERVED.
REPRODUCTION IN WHOLE OR IN PART WITHOUT WRITTEN PERMISSION IS STRICTLY PROHIBITED.
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1981/10-04

INTRODUCTION
Donnell Hewett

Introduction

This publication is the result of a long and disappointing effort trying to inform the hang gliding community of a unique towing technique being developed in South Texas. An original series of four articles entitled "SKYTING - AN OPTIONAL TOWING TECHNIQUE" were written as of December 1980 and submitted for possible publication in Hang Gliding magazine, the United States Hang Gliding Association publication. From all indications, the Editor intended to publish the complete series, but after the first article appeared in the April 1981 issue, certain members of the USHGA Board of Directors felt that to continue the series might be encouraging potentially dangerous activities. As a result, the last three articles were never published.

In June 1981, when I received an explanation, an apology, and my original material back, I submitted the series to Glider Rider. But understandably, the were neither interested in republishing the first article nor in publishing only the last three - particularly since the contained material was admittedly unproven, evolving, and six months out of date. I made no attempt to publish the articles elsewhere because I felt that they would probably be rejected again on the same grounds.

Glider Rider suggested that my best course of action may be to wait until the techniques being developed are more thoroughly tested and proven, and then revise the articles for publication. Unfortunately (or fortunately, depending upon your point of view), skyting has already reached the stage of development where advancements made by one or two persons will be quite slow in coming. This is because skyting, as it now stands and without further development, already meets the needs of the few who are currently practicing it. The questions that remain, although numerous, deal primarily with what happens when other pilots, other equipment, and other situations are encountered. It will be several years before I gain the flight experience to adequately compare skyting with other modes of flying hang gliders, years before I obtain the financing to buy various types of more modern gliders and equipment for testing their compatibility with skyting, and years before I develop the expertise to test fly the skyting system under more demanding conditions. (I have already pushed myself beyond my ability and paid dearly for my mistake.) In short, what will take me years to learn on my own could be evaluated by other, more experienced pilots in a matter of months. Meanwhile, how many pilots will be killed or injured repeating the same mistakes others have already made?

So I decided to publish the series, myself, in the form of a magazine in order that it could be updated as new information became available. But if I am going to the trouble and expense of publishing a magazine, I might as well try to meet other needs as well as the one mentioned above. The goal of this publication is, therefore, fivefold:

(1) TO INFORM WHOEVER IS INTERESTED ABOUT THE CURRENT STATUS OF SKYTING AND THE PROGRESS MADE IN ITS DEVELOPMENT.

By including the original four articles on skyting instead of updated versions, not only was I able to save considerable time on my part, but you, the reader, are given the opportunity to observe the development of skyting from its beginning. As time goes on, you can judge for yourself whether these four articles were prematurely submitted or postmaturely publicized.

(2) TO ENCOURAGE OTHERS TO SHARE THEIR KNOWLEDGE, OPINIONS, AND EXPERIENCES CONCERNING HANG GLIDER TOWING TECHNIQUES.

Considering the number of people interested in towing hang gliders and currently practicing conventional towing (See the July-August issue of Whole Air Magazine), it is appalling to find so little information about towing in the literature. Certainly towing instruction should be performed orally by qualified personnel, but must all communication be by word of mouth?

(3) TO PROVIDE A VEHICLE FOR COMMUNICATION BETWEEN PERSONS DOING RESEARCH RELATED TO HANG GLIDING IN GENERAL AND SKYTING IN PARTICULAR.

Less than 10 years ago, everything done in hang gliding was done by amateurs. Today it is the professionals who are running the show. Certainly most of the money and attention will (and should) continue to go to professionals within the industry, but the voice and contributions of the experimenter should not be neglected. One does not have to be a recognized member of the establishment in order to have ideas, experiences, or opinions that could be of value to others. More communication and education, not more silence and ignorance, are the answers to progress and safety.

(4) TO PROVIDE MYSELF WITH A MEANS OF EXERTING AT LEAST A LITTLE INFLUENCE UPON THE FUTURE DEVELOPMENT OF SKYTING.

As more pilots become familiar with skyting and its potential, there is a real possibility that it will be abused instead of used. If skyting really catches on, then someone is going to say, "It sounds so good, so easy, so cheap, and so safe, and since everybody else is doing it, I'll do it too." Such an attitude is bound to get somebody injured or killed. (I believe this is what those USHGA Directors were afraid of and why they insisted that USHGA have no further part in promoting the system.)

By publishing the magazine myself, I can insist that the negative aspects of skyting be publicized as well as the positive aspects, so that, hopefully, everyone acquainted with skyting will also recognize its dangers and the need for caution and restraint.

(5) TO ENCOURAGE MYSELF TO CONTINUE THE DEVELOPMENT OF SKYTING BEYOND MY OWN SPECIFIC NEEDS.

It would be immoral to develop a system of towing with the potential of skyting without sharing it with others. But human nature being as it is, and with such limited time and finances, how far would I go beyond my own needs without some sort of extra motivation or encouragement? By committing myself to this publication, I am essentially forcing myself to go a little farther.

Just how much farther I will go and how long SKYTING magazine will continue to be published depends upon the response it receives. I am personally committed to at least six more issues even if I have to do everything myself. However, without assistance, progress will be slow. With others donating time, contributing articles, and buying subscriptions, the frequency, the quality, and the content of this publication will improve accordingly.

Donnell Hewett,
Publisher
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1981/10-05

SKYTING - AN OPTIONAL TOWING TECHNIQUE
PART I: Gradual Advancement Provisions
Copyright 1981 by Donnell Hewett

The vast majority of the population of the United States lives in an area where suitable mountain flying sites are not readily available. As a result, regular foot-launched hang gliding is off limits to most of us. In fact, without a mountain nearby, our choice of hang gliding consists of flying motorized or towing. For those unable to afford a motorized ultralight or who are allergic to the noise they generate, there is one option left: towing.

But conventional towing has a reputation of being dangerous - particularly when it comes to lock-outs, land towing, glider modifications, inexperienced ground crews, and inadequate training programs. So what are we, who live on a low budget remote from any known instruction programs to do? The answer, although somewhat sobering, is obvious: Develop your own towing method.

This series of four articles is about one such method - the SKYTING method. The word SKYTING, itself, is a contraction of the phrase SKY KITING. The method consists of a particular technique of towing a hang glider overland - a technique which has been developed over the last couple of years by the author and some of his associates in the flat lands of South Texas. It differs in several respects from other known towing techniques and shows considerable promise in overcoming many of the dangers and difficulties frequently associated with towing a hang glider overland. In fact, once it has been perfected, skyting may well turn out to be the cheapest, the easiest, the fastest, the most convenient, and the safest way to learn and practice hang gliding.

CAUTION

At its current stage of development, skyting may be hazardous to your health. Skyting is so new and the number of skyters so few that the various limits and dangers associated with it have not been adequately explored. Nor have proper methods of teaching it been perfected. Anyone who attempts to skyte at this time must realize that it is still experimental and should only be practiced by those willing to accept the additional risks associated with pioneering a new aspect of aviation.

For this reason, the author fully intended to refrain from publicizing the skyting technique until considerably more experience had been gained concerning it and methods of teaching it. But as more and more people became aware of the skyting technique, those curious for more details and those impressed with its potential continued to encourage the author to publish information concerning it.

Another factor that influenced the author to prematurely publicize the skyting technique is the fact that as many as 60% of the hang gliding fatalities reported in 1979 might have been avoided if the pilots had been aware of and using the skyting technique. For example, skyting may have been able to help save lives in the following three catagories: (1) inexperienced pilots flying at sites and in conditions beyond their level of proficiency (assuming they were doing so because there were no available transition sites), (2) advanced pilots testing modified or experimental equipment from advanced sites (assuming they were doing so because there was no readily accessible method of making preliminary flight tests), and (3) pilots flying motorized gliders in the flatlands (assuming they were doing so because they knew of no other way to get into the sky).

For these reasons the author has decided to go ahead and prematurely introduce the skyting technique to the hang gliding community through this series of four articles. The first three of these articles are somewhat theoretical in nature dwelling primarily upon the philosophical reasons explaining why skyting utilizes certain techniques. The last article is more practical in nature and discusses how these techniques are being applied in South Texas as of December 1980.

BASIC ELEMENTS OF SKYTING

So what is skyting? Specifically what does it consist of? How does it differ from other forms of towing? And why should it be expected to be safer?

Well, to begin with, skyting is a package consisting of four basic elements: (1) a gradual advancement plan - to eliminate that "What am I doing here?" situation, (2) tension limiting devices - to prevent catastrophic failures while under tow, (3) a center of mass bridle system - to insure proper trim and flight control while under tow, and (4) a quick release mechanism - to provide a rapid and safe transition from tow flight to free flight.

Each of these elements will be discussed in reasonable detail in this series of articles, but it should be mentioned that skyting consists of the whole package. Eliminating any one of these elements, or substituting one or more of them into an existing conventional towing system may well result in a situation considerably more dangerous than the original. For example, using the gradual advancement plan and towing over land without the control afforded by the center of mass bridle system will in all probability result in a number of broken spars and bones. Similarly, using the bridle system without a proper quick release could place a pilot in considerable danger in the event of an emergency.

THE QUANTUM JUMP PHENOMENON

In the science of physics there is a phenomenon known as the "quantum jump" wherein an atomic system posessing a certain amount of energy suddenly changes to an entirely different energy level without ever having existed in the intermediate states. There is a similar phenomenon in hang gliding, wherein a pilot at a certain level of proficiency suddenly finds himself in a situation entirely unlike anything he has experienced before. In physics the quantum jump is good, being responsible for such things as the emission of light and the stability of the atom. In hang gliding the quantum jump is bad, being responsible for such things as injury and death. In fact, approximately 50% of the reported 1979 hang gliding fatalities are the direct result of pilots failing to follow a procedure of gradually advancing from one level of skill or experience to another. A student moves from the beginner hill to the advanced hill, an experienced pilot tests a new development from the top of a mountain, etc.

Now it is common knowledge that altitude is an important safety factor in many aspects of aviation. Everyone knows that altitude gives a pilot the time he needs to make proper corrections for an unexpected development. But who in his right mind would suggest that the correct method of learning to hang glide is to launch the beginner off a 2000 ft cliff in order for him to have plenty of time to learn to fly on the way down? It should be obvious to everyone that on his first flight, a beginner should never exceed a height of 3 ft. above ground level, and that he should master the takeoff and landing at that level before proceeding higher. But when should he proceed, and how much higher should he go?

SKYTING ALTITUDE LEVELS

The skyting gradual advancement plan is based upon the premise that a person should never fly more than twice the height he has already thoroughly mastered. To assist the student in gauging his progress, skyting has established a scale of altitude levels, which begin at 1 meter (3 ft) and double for each level thereafter. Table 1 shows the first ten of these levels.

SKYTING LEVEL
ALTITUDE IN
--METERS
--FEET

01 001 0003
02 002 0006
03 004 0006
04 008 0025
05 016 0050
06 032 0100
07 064 0200
08 128 0400
06 256 0800
10 512 1600

Table 1. Skyting Altitude Levels

Mathematically a pilot's skyting altitude level L is defined through the equation

L = 1 = log2 H

where H is the height in meters (above ground level) at which the pilot has repeatedly demonstrated his ability to fly consistantly under complete control and feels both confident and comfortable while doing so.

In our training program we require every student, regardless of his previous hang gliding experience, to begin at level 1 and progress successfully upward after mastering each of the previous levels. We also test rebuilt, new and unfamiliar equipment in a similar manner. The rate of progress depends considerably upon the student and situation. An advanced hang glider pilot may only have to make one flight at each level - actually the skyting technique is so new that so far no advanced pilot has even tried it - while a beginning student may require 10 to 20 flights or more at each level.

As we gain more experience in training students we hope to develop a clearer definition of what constitutes "mastery" at each level. Right now we consider five consecutive flights at a given level, each under total control, to be a reasonable indication that a student has mastered that level. But this is not a hard and fast rule. As long as everyone involved (pilot, instructor, observer, and driver) agrees that the student is ready to move on up, then he may do so. Generally we follow the pilot's own recommendation because he usually knows better than anyone else when he has mastered a given level. We never encourage a pilot to advance faster than his natural tendency, and so far we have not had to hold back a pilot who is in too big a hurry. Everyone so far has recognized the need to thoroughly master each level before progressing to the next.

This does not mean that mistakes have not been made. In developing the skyting technique, we have had a number of accidents which have resulted in bent and broken glider components as well as bruised, cut and scratched bodies. But this is not particularly surprising, considering the fact that none of us had had any appreciable previous hang gliding experience and that in essence we were rediscovering the techniques and dangers of towing a hang glider over land at the same time we were learning, on our own, how to fly a hang glider.

In the process of exploring a large number of potentially promising aspects of land towing flight, we intentionally exceeded the limits of safe operation even though safety was our primary concern. We made it a policy to analyze every mishap and attempted to eliminate the causes from our towing procedure. As experience was gained and the skyting technique became better refined, the number of accidents decreased accordingly.

This is not to imply that accidents have been entirely eliminated, they still happen. For example, my most serious accident to date occurred only a week ago when I was trying out a new aspect of skyting - the result was two bent downtubes, a broken altimeter, a few bruises and scratches, and some injured pride. As I have said before, skyting is still under development.

PROFICIENCY RATINGS

Notice that there is no direct correlation between a pilot's skyting level and his USHGA proficiency rating. The latter constitutes a demonstration of flying ability to an official observer while the former specifies a certain level of progress to the pilot himself. Furthermore, the USHGA system is designed to determine whether or not a pilot is qualified to fly certain sites under certain conditions, while the skyting system is designed to indicate when and by how much a pilot should advance in his stages of learning.

Never-the-less, there is an indirect correlation between a pilot's skyting level and his USHGA rating. Again, based upon limited experience, it would appear that a level 3 pilot should be able to pass his Beginner (Hang I) requirements, a level 6 pilot should be able to pass his Novice (Hang II) requirements, and a level 9 pilot should be able to pass his Intermediate (Hang III) requirements.

By the time a student reaches level 9 he is towing consistently, under complete control, and comfortably to a height of 800 ft, and making flight essentially equivalent to a foot launch off a 1600 ft hill. He should have mastered most of the standard flying techniques and maneuvers including stalls, speed control, figure 8's, 360 degree turns, etc. When he gets to levels 10, 11, and 12, he should be catching thermals and going cross country. By this time the difference between skyting and conventional hang gliding is relatively minor.

LAND TOWING

Sometimes I am asked why skyting restricts itself to land towing rather than water towing, especially since the latter is more forgiving of mistakes and probably safer. My answer is that skyting is not restricted to land towing. A person may skyte behind a motorcycle, automobile, van, truck, boat, or anything else that has the power. He may also hand tow or even rope soar (kite) using a line anchored to the ground. Whether he flies over dirt, grass, fences, trees, water, or anything else really makes no difference. Never-the-less, it appears to me that land towing has more advantages than water towing.

Water towing has one advantage: the presence of a large, flat, and reasonably soft area in which to crash. Land towing has many advantages: it is cheaper, more convenient, more accessible, suitable for cold weather, less traumatic for non-swimmers, requires fewer alterations of the glider, and provides a firm footing regardless of where one takes off or lands. Land towing is definitely superior in the early stages of skyting when a large number of short flights is required, while water towing may prove to be superior in the later stages when it is difficult to find a large tract of unobstructed flatland suitable for towing to higher altitudes or for making prolonged flights under tow.

By the way, prolonged land towing flights are definitely to be discouraged. One should always climb out at a reasonable rate to the appropriate altitude, level out gradually, and free flight down, making it a point to land into the wind at the center of the "runway." Prolonged flight at low altitude over land can be quite dangerous, and is certainly an indication of poor judgement on the part of the pilot. Sure it's fun, but one learns more, faster, and safer by towing up and flying down. When flights to your current altitude level become too boring to satisfy your needs, then it is probably time to move on up to a higher level. Conversely, if you do not feel confident enough to go higher up, then you certainly have no business playing around at low altitudes.

In our next article we will consider the forces involved in towing a hang glider and discuss various methods of limiting these forces.
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1981/10-06

SKYTING - An Optional Towing Technique
Part 2: Limiting Towline Tension
Copyright 1981 by Donnell Hewett

In part 1 of this series of articles we discussed the importance of including a gradual advancement provision in any method of learning to hang glide and how the skyting altitude level system could be used to evaluate a student's progress and to guide him in his rate of advancement. In this article we shall consider the forces involved in towing a hang glide and discuss various methods which may be used to regulate and limit these forces.

FORCE ANALYSIS

Because hang gliders are built and designed to fly under free flight conditions rather than under towing conditions, an understanding of the free flight forces is important. Figure 1 shows the forces acting on a hang glider flying "straight and level" under free flight conditions. From Figure 1a it can be seen that there are only two forces: W is the total weight of the glider-pilot system and acts through the center of mass of the system, while A is the resultant of the forces due to the air and is effectively applied at the center of lift of the system. Figure 1b shows these same two forces drawn in a separate force diagram.

Frequently the force A is resolved into components along and perpendicular to the flight path of the glider. When this is done, the perpendicular component is called the lift L and the parallel component is called the drag D. These are shown in Figure 1c. In our analysis we will not find this resolution necessary, nor will we need to concern ourselves with the angle of attack that the keel makes with the flight path of the glider. For our purposes, therefore, Figure 1b represents the forces acting on a hang glider in free flight.
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Fig. 1. Free flight forces.
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It is important to realize that W, the force due to gravity, is a constant force, never changing in magnitude or in direction. The force A due to the air, however, changes appreciably under dynamic flight situations. In fact, it is the force A and its variations which are responsible for the flight characteristics of the aircraft. Normal free flight of a hang glider, therefore, consists of controlling the variations of A under the constant pull of gravity W.

However, when the glider is under tow, there is another variable force acting on the aircraft, namely the tension T in the tow rope. Because of the variability of the tension in the towline and because of the way it is attached to the glider, flying a hang glider under tow can be dramatically different from flying it under free flight conditions. Never-the-less, there is one condition under which tow flight is essentially identical to free flight, namely when the tow line tension is constant (in magnitude and direction) and distributed uniformally through the center of mass of the hang glider-pilot system. In this special case, the tow force acts on the glider the same as does the force of gravity, so that its effect combines with that of gravity to produce an apparent or effective weight as shown in figure 2.
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Fig. 2. Towed flight forces.
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Figure 2a shows the three forces involved in tow flight. Figure 2b illustrates the effective weight W' which results from combining the towline tension T with the weight W. If Figure 2b is rotated, the result is Figure 2c. The effect is the same as if the whole world were rotated, including the earth, sky, horizon, glider, pilot, and all.

By comparing Figure 2c with 1b, it is obvious that as long as T is constant so that W' remains constant, the forces governing towed flight are exactly equivalent to those governing free flight over a tilted earth of slightly greater than normal gravitational pull. It follows that the flight characteristics of such a hang glider under tow are identical to those it has while flying free. The craft is no more difficult to handle nor is it any more dangerous to fly under tow than under free flight. Obviously the objective of any towing system should be to approximate the above condition as closely as possible.

ROPE LENGTH

Unfortunately there are certain practical limitations in achieving the above conditions. One obvious problem is the finite length of the tow. As the pilot moves to the side or climbs above the tow vehicle, the angle of the tow force changes. Since the direction of the tow force changes, the direction (and even the magnitude) of the effective weight changes also. Never-the-less, as long as the towline is long compared to the motion of the glider, this change is relatively gradual and the tow force is reasonably constant during any particular portion of the flight. Obviously the longer the tow rope the better, as far as this phenomenon is concerned. For this and other reasons, we never tow with a rope shorter than 100 ft and never attempt significant manouvers on a rope shorter than 400 ft.

The main problem in towing is not that the direction of the tow force changes, but that its magnitude can vary dramatically whenever the glider attempts to move at a different speed than the tow vehicle. In fact, if the tow line is not permitted to stretch, slip, or break, then the forces can easily exceed the limits of controlled flight or even the limits of the structural strength of the glider. And no one enjoys flying a glider they cannot control or one that collapses in flight.

CONSTANT TENSION DEVICES

Probably the most ideal tension limiting device available today is the power winch, capable of feeding line out or taking it in at a preset but adjustable value of the tension. It consists of a drum or reel with the towline wrapped around it and a power drive to haul the line in as fast as necessary. Constant tension is provided by a friction clutch which lets the drum slip and feed the line out at the given tension setting. Regardless of the speed of the glider, the power winch tries to pull it faster, but the friction clutch slips the required amount to maintain constant tension as the glider resists the pull. It is hard to imagine a more ideal tension limiting device. Unfortunately, the cost of such a machine is quite high, especially if it is a reliable one capable of guaranteeing constant tension and preventing backlash and jamming as the line is repeatedly fed out and hauled in, or if it is suddenly released in an emergency situation.

By eliminating the power aspect of the winch, the cost can be reduced considerably. But a winch that cannot winch is not a winch, it is a reel. It is able to feed the line out at a constant tension but cannot haul it back while the glider is under tow. (Some reels can reel in the line after the glider has released.) As long as the tow vehicle is moving faster than the glider, then the line is being fed out at a constant tension and the result is essentially the same as for the power winch. However, if the glider flies faster than the tow vehicle or when the end of the line is reached, the effect is the same as if the reel were not there.

Although the friction reel is less expensive than the power winch, a reliable one is still quite expensive, easily costing more than $1000.00. Our budget could not even begin to afford such an investment, so we were forced to look at alternate methods of regulating our towline tension. We considered numerous types of alternate devices based upon both friction and hanging weights, but theoretical analysis indicated that certain practical difficulties would be encountered with each. Being firm believers in trying the simplest solution first, we decided to explore the possibilities of stretching devices before trying these more exotic schemes.

STRETCHING DEVICES

If a device capable of stretching a significant amount under normal towing tension is attached to the towline somewhere between the vehicle and the glider, it will moderate the tension considerably. Although the device does not provide the true constant tension mentioned previously, it does prevent the tension from varying rapidly. As long as the stretch is reasonably large, then the tension remains essentially constant during any particular phase of the flight. A stretch of 30 ft for a 150 lb pull should be more than sufficient to cushion the effects of wind gusts and to provide adequate time for tow vehicle speed corrections before excessive tensions are obtained.

Besides providing a reasonably constant tension during each phase of the flight, the stretching device has certain advantages over a pure constant tension device. Specifically, it provides a smooth transition from towing to free flight and vice versa. It also permits a certain amount of tension control by the pilot himself. By speeding up or slowing down, the pilot may change the length of the tow rope and therefore, select his own towline tension within certain limits. If the desired tension is outside the pilot's current range of control, then the stretch usually will give him adequate time to signal the tow vehicle to change its speed.

It should be obvious that any type of stretching device of sufficient stretch at the required tension could be used, including a spring, elastic band (surgical tubing), bungie cord, or the natural stretch of a nylon towline. Regular parachute shroud line (1/8 inch nylon cord) of rated breaking strength near 800 lbs will stretch about 10% under about 150 lb pull. This means that anything over 300 ft of line will provide the 30+ ft of needed stretch. At 3 cents per foot, this amounts to less than $10.00 for a reliable and smoothly variable tension controlling device. It's hard to imagine a more reliable, more compact, more portable, or more cost effective tension regulator than this, so until one comes along, we will continue to use it in our skyting applications.

By the way, in case you are thinking that 1/8 inch nylon cord with a rated breaking strength around 800 lb is too weak to use safely as a tow rope, then you should realize that skyting is never performed with a tow line tension greater than one "g". In other words, the tension is never allowed to exceed the total weight of the glider-pilot system, roughly about 200 pounds. As long as the tow line can withstand this force, it will never break. If it does break, it will do so at less than this force and no damage is done since the system is designed to recover from such a mild break.

The problem in using shroud line as a tow rope is not that it may break, but that it may stretch too much. If a rope is used with too much stretch (say 1000 ft of line giving 100 feet of stretch), one must be particularly cautious of accumulative effects. The vehicle accelerates, the rope stretches, since the glider is still going slow, the force gradually builds up, the pilot signals to slow down, the truck slows down, but by this time it is traveling so much faster than the glider that even after slowing down it is still going too fast, the rope continues to stretch, and the force builds up to excessive levels. Obviously in order to skyte safely using a long towline having a large amount of stretch requires a good pilot and an experienced ground crew.

GROUND CREW

Regardless of what method is being used to regulate the towline tension or how much stretch the rope may have, the ground crew is still an important aspect of safe skyting. A minimum of two persons is required for the ground crew: a driver and an observer. It is the responsibility of the driver to watch where he is going and to keep the speed of the vehicle proper for safe flying. It is the responsibility of the observer to watch the flight for signs of trouble, relay signals from the pilot to the driver, and react properly in the event of an emergency (i.e. trip the safety release, make the driver stop, get the crash on film, etc.).

By the way, in the case of land towing, it is almost always better to stop the vehicle than to trip the safety release. Because a car can decelerate much faster than the glider, stopping the vehicle relieves the rope tension just as well as tripping the safety release, but without the abrupt change. Although it is possible to imagine situations where it would be necessary to trip the safety release, it has been our experience that tripping the safety release has always been a sign of poor ground crew operation. Our safety release is primarily used to disconnect the tow line from the vehicle after the pilot has released himself from the towline.

TENSION GAUGE

The latest tension regulation device used in skyting consists of a towline tension gauge placed in such a position that it can be observed directly by the driver. Such a gauge enables the driver to tell even better than the pilot whether the tension is too high or too low. As long as the pilot does not initiate some radical manouver or encounter excessive turbulence, the driver is able to respond fast enough to make the speed corrections necessary to maintain essentially constant tension. Although this dynamic control is not as reliable or precise as the more elaborate and expensive friction devices mentioned previously, it is still able to maintain a tension constant to within +/- 25 pounds under most flight conditions.

We have been using a tension gauge for less than one month and certainly have not discovered all of its advantages and disadvantages. Nor have we had an opportunity to evaluate the performance of different types of gauges. Ours is crude, but effective and low cost. It consists of a junked truck hood spring placed inside a plastic pipe calibrated to read up to 200 lbs. of pull. A slit in the pipe enables the driver to see the stretched spring beside the calibration marks or to place his thumb at a particular setting. In the latter case, the driver does not have to divert his eyes from his driving, but is still able to sense subtle changes in towline tension.

WEAK LINK

Every tension limiting device discussed up to now consists of mechanical components, has a limited range, or relies upon human operation. Every one of these tension limiting devices is subject to failure. Please correct me if I am wrong, but it is also my understanding that there are a large number of tow pilots today who are depending upon smooth air, rope stretch, boat speed, mechanical devices, and ground crews to provide the tension limitation control for their flights. Well, in the author's opinion that is just not good enough. Skyting requires the use of an infallible weak link to place an absolute upper limit to the towline tension in the unlikely event that everything else fails.

Now I've heard the argument that "Weak links always break at the worst possible time, when the glider is climbing hard in a near stall situation," and that "More people have been injured because of a weak link than saved by one." Well, I for one have been saved by a weak link and would not even consider towing without one. I want to know without a doubt (1) when I am pushing too hard, and (2) what will break when I push too hard, and (3) that no other damage need result because I push too hard.

Furthermore, I will not use a mechanical weak link no matter how elaborate or expensive because there is always the possibility that it may fail to operate properly. In skyting we use a simple and inexpensive strand of nylon fishing line which breaks at the desired tension limit. There is no possible way for it to jam and fail to release when the maximum tension is exceeded. Sure, it may get weaker through aging or wear and break too soon, but it cannot get stronger and fail to break. If it does break too soon, so what? We simply replace it with a fresh one.

A properly designed weak link must be strong enough to permit a good rate of climb without breaking, and it must be weak enough to break before the glider gets out of control, stalls, or collapses. Since our glider flies level with a 50 pound pull, climbs at about 500 fpm with a 130 pound pull, and retains sufficient control to prevent stalling if a weak link breaks at 200 pounds pull, we selected that value. Of course, a pilot could deliberately produce a stalled break at 200 lbs, just as he can stall a glider in free flight. But if he is trying to limit his climb rate and the forces exceed the break limit, the glider simply drops its nose to the free flight attitude and continues flying. If the weak link breaks (or should the towline break) at less than the 200 pound value, the effect is even less dramatic and controlled flight is still present.

Most people are amazed at how small a string is needed for the weak link of a tow system. In fact, many people upon seeing it in operation for the first time make a comment something like "Don't you need something a little stronger than that? It's going to break!" But, of course, that's the whole point, it's supposed to break. And in order to break at about 200 lbs, it needs to be a single strand (loop) of No. 21 or 24 size nylon cord or a double strand (loop) of No. 12 or 15 size. For our glider we have found through trial and error that a loop of No. 18 braided nylon twine is ideal. A single strand of this twine is rated at 140 lb breaking strength, so a double strength loop should break at 280 pounds. In practice, we have found that because of the knots, it actually breaks at about 200 lbs when tied in a loop and attached to the towline.

Although we suspect that the same weak link would work well with other gliders, we have not had the opportunity to run tests on other gliders to varify this suspicion. Until such tests can be run, we strongly recommend that considerable caution be exercised in determining the correct weak link for any other glider. One should start with a line that definitely breaks too soon, gradually increasing the strength until a point is reached where the glider is able to climb at a good rate without breaking the weak link, but where no stall occurs when the weak link does break.

Obviously, more work needs to be done in this area, but even so, we have found our current system to be quite satisfactory and able to provide the necessary tension limiting and regulation needed for safe and enjoyable flight under tow. Our next article will discuss various methods of attaching the towline to the glider and why the skyting method is to be preferred.
*
1981/10-07

SKYTING - An Optional Towing Technique
Part 3: Center of Mass Bridle System
Copyright 1981 by Donnell Hewett

So far in our series of articles, we have emphasized the importance of having a gradual advancement program and discussed the necessity of utilizing various types of tension limiting devices while skyting. In this article, we shall explain why skyting restricts itself exclusively to the use of a particular type of bridle system - a bridle system which is unlike any other system currently known to be in use today.

FREE FLIGHT

To understand why the skyting system is preferred, let us again review some of the basic fundamentals of hang gliding flight as we did in the previous article. In that analysis, we treated the weight of the glider-pilot system as a single force acting on the center of mass of the system. This time we shall distinguish between the weights of the glider and the pilot in order to better understand how the various forces affect the flight characteristics of the glider.

Figure 3 shows the forces acting on a hang glider freely flying "straight and level" in trimmed flight conditions. Figure 3a is a side view of the hang glider-pilot system and illustrates the weight of the pilot Wp, the weight of the glider Wg, and the force A due to the air acting on the glider. Just as in the previous analysis, we will not find it necessary to resolve the force A into the lift L and drag D components perpendicular and parallel to the path of the glider, and only rarely will we refer to the angle of attack a that the keel makes with the flight path of the glider.
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Fig 3. Trimmed free flight diagram
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a. SIDE VIEW
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KEEL
a
FLIGHT PATH
Wp
Wg
L
A
D
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b. BACK VIEW

A
Wg
Wp
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Figure 3b shows a back view of the same system with the same forces. Notice that under trimmed flight conditions (when the pilot is applying no force to the control bar), all three of the forces Wp, Wg, and A lie along the same line whether viewed from the side or from the back.

Figure 4a illustrates the same thing without showing the pilot and glider. In the rest of our analysis we shall utilize such simplified force diagrams to illustrate the forces of interest and the geometrical relationship between them. These force diagrams are drawn to scale with the glider weight Wg corresponding to 50 lbs, the pilot weight Wp corresponding to 150 lbs, the pilot-glider distance equal to 3 ft and the dashed glider reference line (control bar) of length 4 ft. In figure 4a the force A can be measured to be 200 lbs, as it must support the weight of both the 50 lb glider and the 150 lb man.
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Fig. 4. Free flight force diagrams.
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a. TRIM
b. SLOW
c. FAST
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Figure 4b shows what happens to the forces when the pilot pushes out on the control bar with a force Hg. The control bar pushes back on the pilot with the equal and opposite force Hp. The control bar moves forward (and the glider's nose rises) while the pilot moves backward. The center of force due to the air A is no longer located at the heart bolt (point of suspension of the pilot) but moves backward just enough to keep the glider-pilot system in translational and rotational equilibrium. (In other words, all of the forces and all of the rotational torques cancel on another out so that the glide will continue moving in a straight line with constant speed without spinning, tumbling, or turning.)

The reason that the center of lift has moved rearward is because the angle of attack increased as the control bar was pushed forward. Another effect of the increased angle of attack is an increase in drag and therefore a slowing of the glider. You already know what happens when the angle of attack is made too great - the glider stalls. Obviously too much Figure 4b is to be avoided if at all possible.

Figure 4c shows what happens to the forces when the pilot pulls the control bar backward. The pilot and center of lift move forward, the angle of attack decreases, and the speed increases. Too much of Figure 4c should also be avoided if one is not to exceed the maximum design speed of his glider. This is especially true in gusty conditions when high speeds can result in excessive structural loads on the glider.

SINGLE POINT BRIDLE

Let us now see what happens when the glider is under tow. The result obviously depends upon how the tow line is attached to the glider. It doesn't take a genius to figure out that if the tow line is attached to the nose, the tail, or one wing, then the glider will never get off the ground. But there are many other points where the tow line could be attached. Figure 5 illustrates three obvious possibilities.

Figure 5a shows what happens when a horizontal tow force of 50 lbs is applied to the heart bolt of the glider. (A force of 50 lbs. was selected because it is approximately the minimum force required to keep a hang glider in flight. If the glider is to climb, a larger force would probably be required, say 100 lbs or so.) As the glider is pulled forward, the glider adjusts itself by raising its nose until the air force A not only supports the glider and pilot, but also balances the tension in the towline. The net result is that the glider flies under trim conditions with the control bar rotated roughly 1 ft forward. The effect is somewhat similar to what would happen in free flight if someone moves your control bar 1 ft forward and left everything else essentially the same. Similarly, if the tow force were sideways at 90 degrees to the glider as it would be if the glider somehow got turned crossways while under tow, the glider would bank as shown in figure 5a and the effect would be considerably different than that normally encountered in free flight. In short, towing from the heart bolt is possible, but certainly less than ideal. Oh, by the way, I forgot to mention another problem with heart bolt towing, namely where do you put your head when you get to high tow angles and the tow rope squeezes your head between the two down tubes and your hang strap?
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Fig. 5. Single point bridle forces.

a. HEART BOLT
b. PILOT'S BODY
c. BASE TUBE
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Figure 5b shows the forces resulting from attaching the towline to the center of mass of the pilot (his abdomen). Yep, you heard right. Nope, it's not crazy. Think about it, typically 3/4 of the hang glider system weight is located in the body of the pilot, so that pilot towing should more closely approximate center of mass towing than does glider towing. Figure 5b demonstrates that this is, indeed, the case. Never-the-less, the result is not ideal. The pilot is pulled through the control bar about 4 inches. This makes controlling the glider somewhat difficult because of limited backward correction possibilities and because a person finds it awkward to shift his weight when his hands are located slightly behind his body.

O.K., then, why not attach the towline to the center of the base tube of the control bar? After all, this is the way it was done originally, right? To learn why, look at figure 5c. Notice that in order to fly in trimmed conditions when base tube towing, the pilot has to pull his own body forward through the control bar almost 1 ft in order to counteract the torque caused by the tow force. Measurements of the diagram show that the pilot must exert a force of about 65 lbs himself even though the tow force is only 50 lbs. Have you ever tried to exert 65 lbs with semi-outstretched arms to pull yourself through an opening? And what happens if the pilot exerts less than the 65 lbs? The glider's nose rises, the angle of attack increases, and either the forces increase or the glider stalls. No wonder it didn't take long for the early tow pilots to attach a line to the heart bolt to limit the angle of attack.

By the way, notice what happens when the tow force gets off to the side as would happen when the glider turns crossways to the towline. Figure 5c is then the pilot's view of the forces. A side thrust to the left of 50 lbs causes the glider to bank to the right, so that the pilot must move his body to the left just to maintain equilibrium. If he cannot exert the required 65 lbs, the glider banks even more. This increases the tension in the line, requiring even larger corrections by the pilot. Once the correcting force exceeds the pilot's weight, it becomes impossible for him to stabilize the craft, and unless an emergency release is activated, the glider is going to keep right on banking into the ground. Hmmm, I wonder if there's a name for this phenomenon? Ever heard of a "lock-out"?

MULTIPOINT BRIDLES

All right, so none of the single point bridles would seem to be adequate. What about using a double or triple point bridle system? After all, that's what everyone else does. O.K., let's look at what everyone else does. They apply a bridle system which distributes the towline force at the top and bottom of the control bar. As the glider noses up, more force is applied at the heart bolt, and as it noses down, more force is applied to the base tube. Under trim conditions the top and bottom force must adjust themselves until they effectively act through the center of mass. Figure 6a illustrates the result.
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Fig 6. Multipoint bridle forces.

a. HANDS ON
b. HANDS OFF
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Notice that every force is applied along the line of A just as they are in free flight. As a result, the flight characteristics of the glider will be the same as for free flight. Unfortunately, in order to maintain this equilibrium, the pilot must again exert a considerable force with his own arms. In this case, the force is only about 40 lbs, but even this is beyond the capabilities of most pilots. And if the tow force were allowed to increase beyond the 50 lbs, as it must if the glider is to climb appreciably, the forces would exceed the limits of any pilot. You will also notice that the lock-out phenomenon is less pronounced but just as real in this case as in the single point base tube case.

So what happens when the pilot does not exert the force required for trimmed flight? The glider flies out of trim, as shown in Figure 6b. As long as there is any force on the base tube, the glider increases its angle of attack and the center of lift moves backwards (as in the free flight case shown in figure 4b). The pilot is now able to fly essentially hands off, letting the bridle and flight characteristics of the glider do all the work. But there are two major weaknesses in the system: (1) the glider in not flying under proper free flight trim, and (2) the pilot's control is limited by the stabilizing influence (and lock-out tendancy) of the bridle. The first weakness means that the glider does not behave as it would if it were in trimmed flight. Specifically, the control bar is about 1.5 ft forward like Figure 5a, and the center of lift is about 7 inches backward like Figure 4b. This makes the glider harder to control and more subject to stalls and to excessive gust loads.

The second weakness means that the pilot had better be good and know what he is doing in order to make corrections and give signals to the tow crew before conditions get out of hand. It also means that the tow crew had better be good and know what they are doing because their control over the glider is greater than that of the pilot under the more demanding situations.

THE SKYTING BRIDLE

In the skyting system, the towline forces are distributed between the heart bolt and the pilot. Ideally the system should be designed to distribute the tow force proportional to the weights of the glider and pilot. For our example of a 50 lb glider and 150 lb pilot, this means that the bridle should distribute the forces in a ratio of three to one (3:1). Figure 7a shows the result. Notice that all forces are applied along the line of A, that the combined tension and weight line up along the same line for both the glider and the pilot, and that the pilot is properly positioned in the trimmed position without applying any additional force of his own. In fact, the case is essentially identical to that of a trimmed free flight as shown in Figure 4a, except that the diagram is rotated. This means that the glider will perform the same under tow as under free flight (see part 2 of this series). This is true even if the glider is flying crossways at 90 degrees to the towline, as well as when flying straight behind the vehicle. There is absolutely no tendancy at all to lock-out.
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Fig 7. Skyting bridle forces.
a. 3:1
b. 2:1
c. 2:1 (30 degrees)
d. 2:1 (60 degrees)
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WARNING

The above statement is valid only for the specified conditions, namely (1) that the bridle touches the glider-pilot system only at the heart bolt and at the pilot, and (2) that the tow forces are distributed between the glider and the pilot proportional to the weight of each. If any part of the bridle comes into contact with one of the flying wires or the control bar, as it must if the glider is turned severely crossways, then the stated conditions are not met and a lock-out or a tuck does become possible. It is strongly recommended, therefore, that extreme caution be exercised whenever one of the bridle lines touches a flying wire or the control bar.

A MORE PRACTICAL SKYTING BRIDLE

Having obtained a bridle system that is theoretically ideal, the next step is to devise a more practical system. Suppose, for example, that we simplify the bridle from a 3:1 to a 2:1 system. What would be the difference? Well, Figure 7b shows that there is a difference, but the difference is relatively minor. The control bar moves forward about 2 inches and the effective weights are slightly altered and misaligned, but in practice, the difference is hardly noticed at all. In fact, if a short bridle is used instead of the infinite length bridle assumed so far, the 2:1 bridle does as good a job as the 3:1 bridle in most cases.

For the sake of simplicity, all of our previous illustrations have assumed a horizontal tow force. This is strictly true only at the point of takeoff. In general, the towline makes some angle and pulls down as well as forward on the glider system. Each of the previous figures could be redrawn at various tow angles, but the results would be qualitatively the same. Figure 7c shows the forces for a 2:1 bridle when the tow angle is 30 degrees (on a 200 ft rope the glider would be 100 ft high). As you can see, the result is essentially the same as that in figure 7b.

One of the problems with the skyting bridle is the same as that encountered with the heart bolt bridle, namely that at large towing angles, the upper bridle line gets in the way of the pilot's head. Our solution has been to move the point of attachment forward along the keel about 16 inches. At small tow angles there is almost no difference in performance, but at larger tow angles, the upper attachment tends to pull the nose of the glider down slightly. The theoretical result for a 100 lb. pull at a 60 degree tow angle is shown in figure 7d. Since the glider is slightly out of trim (similar to the free flight situation illustrated in Figure 4c) in the hands off situation, the result is not ideal. However, by pushing out slightly on the control bar, the pilot can overcome this nose down tendancy and put the glider back into the proper flight attitude. In practice, therefore, the glider tends to slow its rate of climb as the tow angle increases, but it can be made to continue climbing by having the pilot push out on the control bar.

In summary, we can say that for every pilot-glider combination there exists a theoretically ideal skyting bridle which eliminates the lock-out phenomenon and provides flight control while under tow essentially identical to that experienced in free flight (as long as no part of the bridle touches the flight wires or control bar), and that the 2:1 skyting bridle is a reasonable approximation to this ideal, under most practical situations. Next time, we will describe how skyting is currently being practiced in South Texas, including certain details for constructing and assembling together the various components.
*

1981/10-08

SKYTING - An Optional Towing Technique
Part 4: Skyting 1980
Copyright 1981 by Donnell Hewett

In our previous articles on skyting we discussed primarily the theoretical aspects of skyting and tried to explain why skyting utilizes such unconventional techniques in its system of towing. Specifically, we have emphasized the importance of a gradual advancement plan, tension limiting devices, and a center of mass bridle system. It is now time to look at the more practical aspects of skyting and see how these techniques may be combined into a viable operating system.

Please remember, however, that the system described below is that used by the author and his associates in South Texas as of December 1980. Since skyting is still under development, by the time you read this article, some of the material may become obsolete.

QUICK RELEASE

Let us begin our discussion by considering the quick release mechanism shown in Figure 8. The major mechanical part of the mechanism (the latch) is available commercially, but a permanent supplier has not been found. We purchased ours from the local surplus store at a very modest cost. All we had to do then we attach the rope and slip on a clear plastic hose (purchased at the local lumber yard) for the sleeve.

The release is attached by locking it onto a ring fixed to the keel of the glider, the body of the pilot, or the end of the towline. It is released by simply pulling on the sleeve. A small rope may be tied around the sleeve and used as a release line if the mechanism is too far away to be reached by hand. As long as the sleeve remains in place, the mechanism holds, and when the sleeve is pulled back, the mechanism releases. We have found the device to be both reliable and durable (as it must in order to work properly after repeated drops to the ground from high altitude).

The only difficulty we have had is that the force required to pull the release increases as the tension in the line increases. When the glider is climbing hard and the towline tension approaches 200 lbs. or so, considerable effort is required to release the mechanism. For this and other reasons, we usually pull in on the control bar or have the driver slow down before releasing from tow.

We do, of course, try to keep the mechanism relatively clean of dirt and sand as we as lubricate it occasionally in order to insure trouble free operation. We also test the release before each flight since the end of the last flight usually resulted in it plunging into the dirt from several hundred feet.

BRIDLE

Two of these releases are used on the skyting bridle, one hooked to a ring sewed to the pilot's harness and the other hooked to the glider's keel about 16 inches forward of the heart bolt.

CAUTION: Any alteration of your glider, especially along the forward keel can significantly weaken the structure unless it is done properly. For this reason, you might be wise to simply tie the keel ring to the heart bolt of your glider. If you decide to tie it to the forward keel, be sure to run a retainer line back to the heart bolt to prevent it from slipping forward while under tow. Also be sure to tie it firmly (without any slack) to the keel and place a cushion of some sort between the ring and the keel to absorb the shock of hard releases. We took our glider apart one time and found numerous dents in the keel due to the ring flying back against the keel after hard releases. The sail cloth showed no signs of wear.

Figure 9 shows the bridle system which we currently use. It is a 2:1 slip ring skyting bridle (see part 3 of this series of articles) with an automatic release line attached to the keel release. Pulleys, of course, would do a better job of distributing the towline force in a ratio of two to one, but we have found the slip rings to be reasonably effective and certainly more reliable and less expensive than pulleys. Our original inexpensive pulleys could not stand up to the repeated drops and wound up breaking at the most inconvenient times while under tow. A high quality pulley system might withstand the abuse, but then again it could get sand and dirt in it and still be little better than the slip rings. The only problem we have had with the slip ring system is that it does produce some wear on the rope sliding through it. But the frayed rope is easy to detect and may be replaced with little trouble and expense when it becomes excessively worn.

The auto release line is tied between the sleeve of the keel release and the top of the towline leader. It is adjusted to tighten just before the two rings come together. When the pilot releases the body latch, the tension in the towline takes up the slack and causes the keel latch to automatically release. If there is no tension in the towline, or if the auto release is not used, the pilot will need to reach up and release the keel latch by hand. This is no big deal under normal circumstances.

Sometimes I am asked if a more conventional release mechanism would be preferred. Specifically one wonders whether it would be wiser to have a release lever right there by the pilot's hand rather than located on his abdomen. Well, yes, it is true that a conventional hand release would be quicker to release than a body release, but in a typical emergency situation, the pilot's hand release is seldom located at the right spot on the control bar to effectively initiate the release, and in a truly panic situation, it is much easier for a person to find a release on his own body than at some specific location on the control bar. Furthermore, it would seem that a single release on the body would be as easy to operate as the two separate releases on a conventional system. The body release also frees the pilot to move his hands anywhere over the control bar and to change from prone to errect flying or vice versa.

I am also asked whether it is really necessary to drop the whole release mechanism from the high altitude at the top of the tow. Well, there are advantages and disadvantages to dropping the bridle system. By dropping the system, there is nothing left dangling in front of the pilot to distract him, nothing to fly back in his face upon release, nothing to become tangled with the pilot, the glider, or the ground during flight or while landing. Conversely, there is additional wear on the equipment and a potential hazzard to persons below, but the equipment can be designed to withstand the fall, and skyting should never be attempted over people or objects which could be injured or damaged by the falling bridle. Further, by using a drag chute on the towline, the terminal velocity of the bridle system may be limited considerably and the danger and damage from dropping the bridle may be reduced accordingly.

CREW

Figure 10 illustrates the total skyting system as it is currently being employed. As mentioned in part 2 of this series, the minimum crew consists of Pilot, Driver, and Observer. Actually, I prefer to fly with three additional ground crew members: an Assistant to help the pilot get ready for takeoff, a Logger to record the relevant information of each flight, and a Photographer to take pictures of important events. Unfortunately, even though we frequently have sufficient Personnel to staff a full five man ground crew, we seldom fly with a full crew. As a result, our records - particularly our photographic records - are less than complete. The main reason for flying with a near minimum crew is the problem of training wuffos in ground crew responsibilities.

VEHICLE

As mentioned in part 1 of this series, the tow vehicle can be anything from a motorcycle to a speed boat. But the best vehicle we have found is a pickup truck. Its main advantage is that it can be used to carry the glider and crew back to launch after each flight. It also permits excellent rear visibility for both observer and driver, even up to very high tow angles. The rear window of some trucks slides open to permit communication between persons inside and outside the truck, so that the observer can ride outside and still give clear instructions to the driver. Normally, the observer would ride inside the vehicle.

TENSION GAUGE

As I mentioned in part 2 of this series, we have recently begun to use a tension gauge to inform the driver of variations in towline tension. By responding appropriately to the tension gauge and the pilot's signals, a good driver can maintain essentially constant tension at whatever value the pilot desires. As shown if Figure 10, we take the gauge described in part 2 of this series, tie one end to the upper dor hinge on the driver's side of the vehicle, tie a strong (about 3/8 inch diameter) rope to the other end, slip the rope through a pulley mounted on a board tied to the rear bumper of the vehicle, and tie the other end of the rope to the safety release.

SAFETY RELEASE

As mentioned in part 2 of this series, our safety release is used primarily to release the towline after a flight, in order to retrieve the equipment for the next flight. Hardly ever is it used as an emergency mechanism. My advice to an observer is to use the safety release only in a true emergency situation, such as when a beginning pilot fails to release when he should, or when an experienced pilot tries to release but cannot.

TOWLINE

As mentioned in part 2 of this series, the main towline used in skyting is 300 ft or more of parachute shroud line (about 1/8 inch nylon cord) which stretches approximately 30 ft before breaking the weak link. This stretch cushions the glider from sudden changes in towline tension resulting from turbulent air or from glider manouvering. Shorter towlines should be used in the beginning stage, and longer ones in more advanced stages, always keeping in mind the gradual advancement policy of skyting discussed in part 1.

PARACHUTE

The drag chute is used to prevent a sling shot or whip lash effect in the event of a weak link break and to limit the terminal velocity of the bridle after release. We got our drag chute from the local surplus store for a modest price and have found it to be quite effective for its intended purpose. Our chute is about three ft in diameter, which seems to be about optimum. It is large enough to prevent the sling shot effect and limit the speed of the falling bridle system, yet is small enough so that its effect upon the towline while under tow is negligible and so that, if the towline breaks or safety release is tripped, then there is no problem controlling the glider with the chute dragging along behind.

WEAK LINK

The weak link, of course, is just that - designed to break at the maximum desired tension of the towline. As mentioned in part 2 of this series, our weak link consists of a loop of No. 18 braided nylon twine which breaks at about 200 lbs. Again, according to the gradual advancement policy of skyting, one should begin with a string that breaks too soon and use progressively stronger strings until a satisfactory limit is established for the particular glider being used.

LEADER

We use a 100 ft leader of 5/16 polypropylene ski rope colored a bright yellow or orange. It stretches very little under the tensions encountered and therefore does not fly back in our face as hard when the weak link breaks. The bright color makes it easier to locate after it is dropped. A shorter leader might be acceptable, but if it is too short the bridle will fly back into the pilot's face after a weak link break. If it is too long, it may get tangled with the glider or ground after a weak link break or when landing.

BRIDLE

As mentioned previously, we use the bridle system illustrated in Figure 9. The glider and pilot's harness have to be altered very little for the skyting system - namely the body ring has to be sewed onto the belt of the pilot's harness and the keel ring must be attached properly to the glider.

TYPICAL FLIGHT

So there you have it, the skyting system as it currently exists in December 1980. A typical flight using the system might be similar to the following:

You have just finished setting up the system on your favorite open field and inspected everything for proper operation. Your observer and driver have just driven the pickup truck to the other end of the towline and your assistant is helping you with your final hang check. Everything is "go" so you pick up the glider and take a few steps backwards to tighten up a little on the towline. Soon you see the brake lights of the truck flash on and off as the driver signals that he is ready. One last time you check the tail-tales on your glider to assure yourself that you are pointed into the wind with the nose angle high enough to catch the air on takeoff, and you make sure that your wings are level, that the glider is completely under your control, that your footing is secure, and that you are mentally ready to go. With a stomp of your foot you are committed. You wait for the truck to start accelerating while you maintain proper control of the glider. As the towline stretches, you hold back slightly until eventually you are pulled forward. Then after about six easy steps you are airborne.

If you have done your job right, the towline tension is just right for a good climb out. If not, then you and your driver will have to make a few speed adjustments to arrive at the proper towline tension. Looking down you see the ground dropping away at about 400 to 500 feet per minute, the view below is exhilarating. But you need to keep your mind on your flying or else you may not climb fast enough to gain enough altitude to make it back to launch, or you may react too slowly to a wind gust and break the weak link. Eventually you see that the truck is approaching the end of its "runway" so you prepare to release. By this time the truck looks like it is directly below you even though you know that the true tow angle is only about 60 degrees. Still your altitude is 90% the length of you towline.

As the truck begins to slow down, you pull in on the control bar to lower the nose to the free flight attitude and release your body release. The auto release line trips the keel release, the bridle mechanism flies away, and you see the parachute drift off to the side as you begin your 180 degree turn down wind. The take off site comes into view and you level out, trimming the glider for minimum sink. As you float down wind over the scenery below, you glance back to see that the truck has turned around and its crew members are in the process of retrieving the bridle system. If your altitude is adequate, you may decide to do a few flight manouvers, otherwise, you begin setting up for your landing. Just for fun, and to show your buddies how good you are, you decide to spot land right at the takeoff position. After all, if you can hit the dime that was placed at the center of takeoff, you can keep it.

On your final leg, you find that you are too high, so you have to land upwind of take off, but as you pass over your assistant and the other wuffos, so you let out a big 'Wah-Hoo!' A few seconds after landing you have carried the glider back to launch and the truck has returned with the bridle and towline. Then, unless you waste a lot of time gabbing with your friends, you can be ready for your next flight in about two more minutes. Now if this sounds like fun, let me assure you - it is.

CAUTION

One last time let me emphasize that the skyting system described in these articles is still very new and has not been properly tested. Therefore, it should not be attempted until professional instruction is available. The only reason for this disclosure is to inform the hang gliding community that an alternate and potentially safer tow method does exist and is under development. It is hoped that by doing so those pilots determined to fly without proper instruction may have a better chance of surviving. If the result of these articles is to encourage others to attempt flying who otherwise would not, then I have indeed performed a disservice to the hang gliding community.

Whether or not and to what extent skyting realizes its potential as described in these articles can only be determined through time and further research. So far, skyting research has been carried out and financed by three individuals: Donnell Hewett, Richard Wylde, and Virgil Newman. If you are interested in making a contribution toward further development of skyting, please address your communications to Skyting, 315 N. Wanda, Kingsville, TX 78363. As additional information and experience is acquired concerning the skyting technique, additional articles will be submitted for publication.
+
Fig. 8. Quick release mechanism.

LATCH
SLEEVE
ROPE

LOCK
RELEASE
+
Fig. 9. Skyting 2:1 slip ring bridle system with auto release line.

KEEL RING
KEEL LATCH
AUTO RELEASE LINE
LEADER
BODY LATCH
BODY RING
+
Fig. 10. Current Skyting System December 1980

PILOT
HANG GLIDER
BRIDLE
LEADER
WEAK LINK
DRAG CHUTE
TOWLINE
SAFETY RELEASE
TOW VEHICLE
TENSION GAUGE
DRIVER
OBSERVER
*
1981/10-09

SKYTING UPDATE
Through August
1981

by Donnell Hewett

Since December 1980, several things have happened. Virgil Newman and family moved to Toppenish, WA; Richard (Red) Wylde married Cece; and I broke my arm (while skyting). Needless to say, very little progress has been made in skyting development since December.

During the winter, before I broke my arm, we were able to do a little flying but not much. Winter is our rainy season and the runway was frequently too wet and slippery to fly. (You know? Boat towing may still have its advantages.) During this time we flew primarily for fun, and decided to leave the developmental work until spring and summer.

After Virgil left, we made a more serious effort to train other pilots in order to have someone else to fly with. But because the teaching techniques are still embryonic, we had to advance very cautiously, and because flying opportunities were rare, our best student, Henry Wise, moved to Houston before he even got past level 5. I understand that he is now flying his new Raven with a great bunch of guys - Have fun, Henry, and remember us on the long drives to and from your flying sites.

After I broke my arm, skyting development essentially came to a stand still. There were a few "fun" flights last spring, but no one did any flying during the peak of the flying season (late spring and summer). Everyone seems to be waiting for me to get better. Gee: Aren't they sweet?

After six months, my arm is getting strong enough to fly, and we are planning to go flying in September. Hopefully we will get some useful data on how fast an experienced pilot should advance after being grounded for a prolonged period of time. We also hope that during the next few months we will see more flying done and more development work accomplished than during the last few months. Hey?
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1981/10-10

Apology

The publisher apologizes for the high price of this publication, but the cost of printing, handling, and postage for small volume publications is quite high. Therefore, until and unless the volume of this publication increases and advertisements subsidize its costs, each subscriber must bear the cost of producing his own copy.

Extra Copies

If individuals make additional copies of this material, they are not only breaking the low and acting immorally, they are also making it harder to finance future additions of this magazine. Please send for extra copies if you need them. In lots of six, the cost drops from $2.00 to #$1.67 per issue.

Contributions

If you have information or opinions concerning skyting, conventional hang glider towing techniques, or experimental hang glider developments, please share it with others. Type your contributions single spaced in columns of 3.5 inches wide, and send them to SKYTING, 315 N. Wanda, Kingsville, TX 78363.
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1981/10-11

MY PRIORITIES

by Donnell Hewett

Those of you who do not know me personally may wonder - if skyting is really all that it's claimed to be - then why don't I spend more time, more money, and more effort in developing it to its completion? The reason is simply a matter of priorities. Development of the skyting technique, as important as it is, simply is not at the top of my list of priorities.

My first priority belongs to Jesus Christ, the Son of God, my Savior and Lord. Considering all He has done for me and the love we have for one another, I can do nothing less than commit my life and all that I have to Him and His service. If you know Him personally, then I'm sure that you understand my feelings and will agree that Jesus beats anything this world has to offer - including hang gliding. If you never come to meet Him, then ask someone to introduce you - believe me, until you do, you don't know what you're missing.

My second priority belongs to my family. Helen, my wife, is the greatest companion any man could hope for, and has filled my life with happiness throughout the eleven years we have been married. My daughters, Tahnya (ten years old last October), and Tammi (eight years old last June), are also important in my life. I love all three of my "girls" as well as my parents and my inlaws, so that if it ever comes to a choice between my family and skyting, then hang gliding will lose every time.

My third priority belongs to my profession, I am a professor at Texas A&I University and teach physics, astronomy, and solar energy. I am also conducting research in the field of solar energy in an attempt to develop some truly cost effective solar energy devices (including a solar air conditioner). Since these activities are my primary means of support, are obligations I have voluntarily accepted, and are both enjoyable and fullfilling to me as a person, I consider both my teaching and my solar energy research to be more important than my involvement in hang gliding.

Skyting, therefore, is number four in my list of priorities. I still consider it to be important, both for providing me with a means of personal relaxation and recreation, and for providing others with an opportunity for safe and accessible hang gliding. But in my life, skyting and its development will just have to accept the fact that it gets the time, the money, and the attention that remains after I have met the needs and the obligations associated with the higher priority items mentioned above.
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1981/10-12

DON'T DUIT

by Don Hewett

The Helmet

Hey, don't! You forgot your helmet!
Never mind! I don't need it!
I've got my chewing gum!
*
1981/10-13

From the Logbook

This column is dedicated to the sharing of experiences between pilots. Please review your own logbook and see if anything happened to you that might be of benefit to other pilots. If so, then type it up in single spaced columns 3.5 inches wide and send it to SKYTING, 315 N. Wanda, Kingsville, TX 78363.

HOW TO BREAK AN ARM

Pilot: Donnell Hewett
Experience: 142 flights, 3.7 hours flight time, Skyting Level 8, USHGA Rating: Beginner (Hang 1)
Glider: Sandpiper (second generation Ragallo)
Date: February 25, 1981
Place: Kleberg Co. A.P., TX
Launch: Skyting
Description:

The wind was blowing at about 15-20 mph at ground level from the prevailing direction of southeast, so there was a 45 degree crosswind on our north-south runway. Before reaching us, the air had passed over several miles of King Ranch brush land and among numerous 15 ft trees bordering the airport. There was no question that there was going to be a strong wind gradient and severe turbulence pushing the limits of my flying ability and the limits of performance of my antiquated glider. I recognized the danger involved, but decided to fly anyway. After all, I had flown in worse conditions than these, and was confident that I could handle this milder situation. Besides, if the limits of the skyting technique were going to be explored, flights in these conditions would have to be made.

On my first flight I had a good takeoff, but entered the wind gradient too fast. Suddenly I was climbing hard, so I pulled in on the control bar and signaled the driver to slow down. But because of the low tow angle at takeoff and the large forces involved, the control bar rubbed against the sleeve of my body latch and caused a premature release. The top latch released automatically and I suddenly found myself flying free at a height of about 30 ft. Keeping my speed up while passing back down through the wind gradient, I came in for a landing without any difficulty.

On my second flight, the driver slowed down a little, but the wind gradient was still too strong, and at about 80 ft the weak link broke. Again, I brought the glider down without difficulty.

On my third flight, the driver slowed down even more, and this time I was able to climb on up for a good flight. At about 200 ft everything become glassy - there was no turbulence at all. Boy, this was great!

The van was now going about 5 mph, so I had plenty of time (about 2 minutes) to reach an altitude of 500 ft on a 600 ft line. As the van neared the end of the runway, I had a decision to make: Should I stay on the line and do some moored skyting after the van stopped, or should I release and land?

I had "rope soared" before and enjoyed it immensely, but I knew that I would lose some altitude in doing so and might not be able to make it back to takeoff if I did stay on the line. Besides, this was my first successful flight of the day and it would probably be wiser to stay with basic flying techniques right now. I would try kiting later on in the day.

Having decided to land, I now had to decide where. I could land in the large clearing between runways (which was located directly below me) or I could fly back to the smaller clearing at the takeoff position. Since I had no desire to ground handle the glider in these winds all the way from the large clearing back to the launch site, it didn't take long to decide to fly back to the takeoff position.

After releasing, I made my turn and was quickly carried down wind to the launch site. As expected, when I got back down to the 200 ft level, the turbulence was still there, so I kept my speed up to prevent stalling in the turbulence or when passing through the wind gradient. After completing my final turn, I could see that I was going to land about 50 ft down wind of my goal, but I was still well within the clearing, so I didn't let it bother me. I continued the fast descent through the turbulence and was just about ready to begin my landing flare when, at about 10 ft AGL, the glider suddenly stopped descending. I kept the bar pulled in, but the glider simply would not go down - it just seemed to float there - hovering 10 ft over the motionless ground. And then suddenly - the bottom dropped out. I pushed out hard on the control bar, but in the process, shoved my own body backwards. I hit the ground on my feet, but was slightly off balance - leaning forward. As a result, I fell through the control bar.

Realizing the danger of breaking an arm under such conditions, I relaxed my arm muscles as much as possible to allow myself to swing freely through the control bar. But on the way through, I heard a crack and when my arm hit the ground, I knew it was broken. There was nothing I could do now but wait for the ground crew to come, pick me up, and take me to the hospital.

The break was clean, just above the elbow on the left arm. No operation was necessary, but I wore a cast for over 2 months and had to spend another 4 months rehabilitating the muscles and the joints. (By the way, the only damage to the glider was a slightly bent down tube.)

In retrospect, I can conclude that it was a great flight, but certainly not worth the trouble, suffering, and expense that followed. My primary mistake was flying under the conditions that were present. My secondary mistake was landing in the small clearing at takeoff instead of the large clearing between runways. The accident, itself, was a freak - but it was the type of freak that is eventually going to show up if one keeps flying near the limits of his ability.

One question certainly worth asking is "Did the skyting towing technique contribute to the accident?" The answer is "Yes!" Without the skyting technique, I would not have flown at all, and therefore could not have been hurt. There is no way I would have attempted to fly in those conditions using conventional towing techniques. To attempt a 45 degree crosswind takeoff in gusty, turbulent winds of 20 mph into a correspondingly strong wind gradient using conventional methods would have guaranteed an uncontrolled flight from the very beginning while under tow instead of at the very end while flying free.

In my opinion, the accident demonstrated that the major weakness of the current skyting system lies in my own lack of proficiency and in the lack of response of my obsolete glider. Therefore, these are the areas I am going to work on. In short, I am going to stop "pushing" the skyting system beyond my own limits and start concentrating on improving my flying ability.
*
*

1982/06
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SKYTING NO. 2
JUNE 1982
$1.00
*
1982/06-01

SKYTING magazine is published monthly by Donnell Hewett, 315 N. Wanda, Kingsville, TX 78363; telephone (512) 592-6757. Price is $1.00 per single copy or $10.00 per year. Contributions of news, notes, articles, and illustrations are sincerely appreciated. All illustrations should be line drawings camera ready for photocopy reduction. All requests for return of material must be in writing and a self-addressed stamped envelope enclosed. Notification is required if contribution has been submitted to other publications. SKYTING magazine reserves the right to edit contributions where necessary. Neither SKYTING magazine nor its publisher assumes responsibility for the material or opinions of its contributors.
*
1982/06-02

NEXT MEETING

Our next meeting will be Tuesday, June 8, 6:30 pm, at Cece and Red's house (732 S. 16th, Kingsville, TX). Just look for the house with the hang glider set up in the yard.

Everyone is welcome, but please make reservations for food by calling (512) 595-1370 so they will know how much food to prepare. And when you get there, don't forget to chip in about $2.50 each to help defray the costs.

If you don't eat good food, then come anyway for the fellowship. We are planning to hald a free GROUND SCHOOL covering the general principles of flying, the techniques of piloting hang gliders, and the concepts behind the skyting system.

DON'T MISS IT!
*
1982/06-03

LAST MEETING

The Kingsville Skyters met at Helen and Donnell's house on Monday, May 10. We had charcoal-broiled, home-made hamburgers with tea and potato chips. While stuffing our stomachs, we watched the historical developments of the skyting tow system through the eyes of Red's super 8 movie camera. There were four adults and two children present.
*
1982/06-04

SKYTING UPDATE through MAY 1982

by Donnell Hewett

Several things have happened since SKYTING NO. 1 was published in October 1981. You may be interested in the following:

KINGSVILLE, September 11. I finally got back into the air after breaking my arm last February. (See SKYTING NO. 1.) The flying went great, but while ground-crewing for Red, I sprained my ankle. Hey! What is this? Do you think somebody is trying to tell me something?

HOUSTON, October 3. We demonstrated the skyting system to some of the members of the Houston Hang Gliding Association. Everything went well except that Henry tried to land on a 10 foot tree. After walking across the top of it, he brought the glider on down to the ground and bent a down-tube. Both Red and I received our Hang 2 rating even though I was unable to fly because of my ankle.

KINGSVILLE, November 14. Gary Quarles from Dallas, and Ron Gudry and Eldon Criswell from Houston, were the first pilots from outside the Kingsville area to fly with the skyting system. Gary and Ron were also the first to demonstrate that a higher performance glider (the Oly 160 - a glider noted for being hard to tow) tows very well with the skyting system.

Once they got over their initial apprehension of being the "first outsiders", they progressed rapidly to higher altitudes without incident. On his fifth flight, Gary (experienced with the Oly, but not with towing) maxed-out at 450 ft and flew back to land at take-off. Ron (experienced with towing, but not the Oly) advanced more slowly while anticipating the lockouts which never occurred.

All three pilots were favorably impressed with the new towing system and plan to use it when they got back home.

NOTE: I have heard nothing from any of them as of June, 1982.

CORPUS CHRISTI, April 17, 1982. Eddie Bolls and I skyted on Mustang Island with a north-east wind blowing from the Gulf of Mexaco. This was the first skyting performed on the island, my first flight to 500 ft in smooth air, and Eddie's first flight. Since the winds were almost kitable, this convinced me that safe kiting could be performed in the smooth air along the coast.

KINGSVILLE, April 29. Red test flew his new LEAF TALON hang glider on the skyting system. Everything checked out well.

PADRE ISLAND, May 27. While vacationing on Padre Island with my family I set up my glider and kited. Using a 600 ft line, in winds 15-20 on the ground, 20-25 on top of the sand dune, and 25 mph in the air, I cautiously made my way on up to about 200 ft. I could have stayed up as long as I wanted to, but came down because my harness was uncomfortable. My second flight was terminated because it was starting to get dark. I made two flights and got 15 minutes of air time. There is now no more doubt that under the right conditions safe kiting is possible. "Rope soaring" has tremendous potential for future utilization.
*
DEAR DONNELL
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1982/06-05

Dear Donnell,

It was with great interest that I read your letter and publication on "Skyting". Your analysis of the forces involved in the towing situation satisfied my technical curiosity and let me know you have done your homework.

As to why these articles weren't accepted for printing, I can't imagine. I can see why Glider Rider didn't want to continue the series after the first part appeared in Hang Gliding, but I can't see why Hang Gliding didn't print them all. I do not recall seeing these articles being discussed at any Board of Director's meeting and sat in on most of the Publication Committee's meetings without hearing the same. I can only assume someone personally had a thing to do with it.

My advise to you is to rewrite the material in a single article including the latest information and submit it to Glider Rider. They are especially interested in getting more articles now since hang gliding is waning in their publication. Wherever you submit (if you do), feel free to use my recommendation of the article. I think you are accurate and on the right track. Even if some folks have a difference of opinion, the flying community should hear your ideas.

In regards to your accident, I think you were not just pushing the limits, but way past them. As a point of reference, I don't fly inland in ground wind over 15 mph. You can't thermal efficiently if winds are 20 mph - they drift too fast and are torn apart. Needless to say, the related turbulence is unhealthy. I personally would not tow with any system crosswind at takeoff over 10 mph. I'm sure you have revised your limits.

Dennis Pagen
State College, PA
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1982/06-06

Dear Donnell,

I enjoyed your article in Whole Air magazine on Skyting. Enclosed is two dollars. Please send me Skyting #1.

If your time permits I would appreciate some info. on the following questions.

How does your system handle pop-starts for boat towing?

Is the pilot in control during the initial start?

Robert R. Miller
Richmond, MI
*
1982/06-07

Dear Robert,

Thank you for your interest in skyting. Enclosed is the SKYTING NO. 1 issue you requested. I hope it answers most of your questions regarding our towing system. If you have any other questions, comments, or suggestions concerning skyting and how it is practiced, please feel free to send them to me. I will do everything I can to keep the lines of communication open.

In your letter, you asked how our system handles pop-starts for boat towing. Well, pop-starts and boat towing are two aspects of skyting that have not been adequately explored. I am sure that you know more about both of these than I do Bear this in mind as you read the following discussion and evaluate the situation in accordance with your own knowledge.

I am confident that skyting can handle pop-starts better than conventional towing if for no other reason than the fact that it distributes the thrust between pilot and glider proportionally to their weights. This means that both the pilot and the glider will be accelerated forward equally, with neither being "left behind". (In conventional towing, the towline pulls on the glider which pulls on the pilot, so the pilot is "left behind".) Of course, pop-starts would still constitute an "advanced manouver" appropriate only for experienced pilots who have the skill, knowledge, and techniques necessary for executing such tasks with full confidence and safety. Never-the-less, I have philosophical objections to pop-starts, and would personally consider using them only if conventional skyting take-off proved to be impractical.

My first objection to pop-starts is that they violate one of skyting's basic requirements. Ideally, skyting demands that the towline tension remain always constant. In practice, this means that the towline tension should never vary rapidly compared to the pilot's reaction time. Other examples of towing situation wherein this rule is violated are (1) breaking the weak link, (2) tripping the emergency release, and (3) releasing from tow under full tension. Although skyting can and does handle these situations, they are considered to be more dangerous than normal flying and are almost always the result of poor techniques. I suspect (but without experience I do not know) that pop-starts would also be more dangerous than normal flying and constitute an example of "poor technique".

My second philosophical objection to pop-starts is related to your second question, "Is the pilot under control during the initial start?" Here you should realize that the whole idea behind the skyting technique is to take flight control out of the hands of the ground crew and place it in the hands of the pilot. Therefore, in a normal skyting take-off, the answer to your question is, "Yes!" But in the case of a pop-start, the answer must be, "No!" In a normal skyting take-off, the tension increases gradually and the pilot is free to decide when, if, and how he wants to take off (within broad limits, of course). But in a pop-start, the pilot is waiting for a "happening", and when it "happens", he better be ready, willing, and able to cope with it. He cannot decide half-way through a pop-start to stop and try again. This is a characteristic of pop-starts and not towing systems. No matter what towing system is used, it is impossible for the pilot to be in control throughout a pop-start. He can learn to handle them (just as he can learn to handle turbulence) but he cannot control them (just as he cannot control turbulence).

I am hoping to do some boat towing this summer, and when I do, I plan to first try a standard skyting take-off. Only if that proves to be impractical (and I can think of no reason why it should be impractical) will I pursue the pop-start option.

In case you have difficulty deducing our standard take-off from the volume of data in SKYTING NO. 1, let me outline the procedure here:

I. Use a stretching device on the towline to guarantee that the tension varies only gradually.

II. Pull the towline straight (but not stretched) before take-off.

III. Have the vehicle (boat) accelerate as fast as possible until:

(1) the winch begins feeding line out,

(2) the tension gauge reads normal for towing, or

(3) the air speed indicator on the boat reads normal for towing.

IV. Have the pilot hold back on the towline as the tension builds up and, when the conditions are right for take-off, start running.

Under these conditions the pilot will be airborne in only a few easy steps. If at any time during the take-off procedure the pilot feels himself going out of control, he can either decide to "ride it out" (by taking corrective measures) or to "abort the flight" (by releasing himself from tow).

I hope this answers your questions. Please let me know if you have others. I would appreciate some feedback as to how you feel about the skyting system after reading SKYTING NO. 1. So far I have sent out several copies of SKYTING NO. 1, but have recieved very few comments from those who have recieved them.

Donnell
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1982/06-08

THE SKYTING TAKEOFF

by Donnell Hewett

NOTE: The following article assumes that you are a conventional hang glider pilot with a USHGA rating of 3 or more. You are familiar with normal foot launching from the side of a hill, but have had no previous towing experience. It also assumes that you have read SKYTING NO. 1 and are familiar with its contents.

The skyting takeoff is considerably different from that of conventional foot-launched hang gliding. In order to understand why, let us review some of the concepts presented in SKYTING NO. 1.

To begin with, you will recall that skyting is equivalent to free flight over a tiltad earth of slightly stronger gravity. (SKYTING NO. 1, p 5) The amount of tilt (the tilt angle) depends upon the tow angle (the angle the towline makes with the ground) and the tension in the towline.

During takeoff, the tow angle is zero, and the tilt angle is proportional to the towline tension. Mathematically the tilt angle b is determined through the equation

tan b = T/W ,

where T is the tension in the towline and W is the weight of the glider-pilot system.

As an example, suppose that the towline tension is 100 pounds during takeoff, and the total weight of the pilot-glider system is 250 pounds, then the tilt angle is found to be 21.3 degrees. This is actually a pretty steap hillside and corresponds to a glide ratio of L/D = 2.5.

Fig. 1 illustrates how this tilt angle effects the skyting takeoff. Fig. 1a shows the case of a conventional foot-launched takeoff from a slope of 21.8 degrees. The pilot is standing upright and the glider in in the horizontal (neutral) position. Fig. 1b shows this equivalent skyting takeoff obtained through the 21.8 degree angle. Here the pilot is seen to be leaning back (resisting the pull of the towline), and the nose of the glider is tilted upward at the 21.8 degree angle.

To get an idea what would happen if a pilot tried to make a "conventional" takeoff while skyting, look at Fig. 2. Fig 2a shows the pilot in the normal horizontal position. Fig. 2b shows the corresponding takeoff from the tilted earth. The glider is pointed 21.8 degrees nose down and the pilot is completely off balance (leaning forward 21.8 degrees). You can probably imagine what would happen if a pilot actually tried to launch from this position. He is going to fall flat on his face and nose the glider into the ground. Well, the same thing is going to happen to the skyting pilot in Fig 2a, because the two cases are identical.

MORAL: Get the nose up and hold back on the towline when making a skyting takeoff.

Now the second skyting concept you should remember here is that ideally, the tension in a skyting system should remain absolutely constant. (SKYTING NO. 1, p 5) However, during the takeoff manouver, it is impossible to keep the towline tension constant. The tension must go from zero prior to takeoff to full thrust after takeoff. This is one of the reasons for using a stretching device in the skyting system. You will recall (SKYTING NO. 1, p 6) that the main advantage of a stretching device over a true constant tension device is its ability to allow the tension to vary, but to prevent it from varying rapidly. (See also the discussion on pop-starts in the Dear Donnell column of this issue of SKYTING.)

Since the tow force increases during takeoff, the corresponding tilt angle also increases. The result is very similar to taking off from a tilting platform or from a rounded hill top (although the situations are not exactly equivalent to one another). Fig. 3 illustrates the similarities and the differences between the skyting takeoff and the similar free-flight takeoffs. Fig. 3a shows a normal skyting takeoff, and Fig. 3b shows its tilted earth equivalent. Fig. 3c shows a normal free-flight takeoff, and Fig 3d shows its skyting simulation. Notice that in the simulated situations (3b and 3d) the pitch of the glider varies during the run, while during the actual takeoff situations (3a and 3c) the glider starts out with its nose already in the proper takeoff attitude - high for a skyting takeoff and neutral for a free-flight takeoff. This makes the actual takeoff easier than the simulated cases because the pilot does not have to adjust his nose angle according to the slope of the hill or the pull of the towline.

In the preceeding discussion we considered the theoretical aspects of a skyting takeoff. In the following discussion we shall consider the practical aspects. Specifically, we will describe step by step what you should do to make a skyting takeoff.

1. INSPECT EQUIPMENT - As in conventional hang gliding, so in skyting, never attempt a flight without properly inspecting the system. Always preflight the glider and check the skyting equipment.

2. HOOK IN - It is our practice to follow the following proceedure when hooking in. (1) Attach the keel latch. (2) hook the pilot in. (3) hang check, and (4) attach the body latch. The idea is to never attach the body latch until after the pilot is hooked in. Since the pilot cannot takeoff without attaching the body latch, this prevents him from attempting to take off without being hooked in.

Of course, failure to hook in is not as dangerous when skyting as when mountain flying because the pilot can release himself and never leave the ground. But if this ever happens to you, just remember that the same thing on the side of a mountain could have gotten you killed. Just because skyting forgives certain mistakes is no reason to become careless!

3. STAND UP - This signals the vehicle that you are almost ready for takeoff. At this time you should also pull the towline straight and check to see that it is not snagged on the ground. You should also check the bridle lines once more to make sure they are not twisted or tangled. They you look at the vehicle to see if it is ready to go. (Flashing the break lights is our signal that the vehicle is ready.)

4. FINAL CHECK - After the vehicle signals it is ready, make a final check of the conditions. Is the wind right? Are the wings level? Is the nose high and at the right angle (about 20 degrees to 30 degrees)? Are your flight instruments turned on (if you are using any)? Is the flight path clear? Are you, yourself, ready?

5. GO - When everything is right, signal the vehicle to go. (Our standard signal is to kick one leg straight outward to the side while standing on the other.) Although you are not yet moving, your takeoff has now begun. The vehicle is starting to accelerate and the towline tension will soon start to build up. At this point you should concentrate on three things: (1) keep your balance, (2) keep the wings level, and (3) keep the nose high. If a wind gust tries to blow you to the side, then don't fight it. Go ahead and move to the side - just keep your balance, the wings level, and the nose up.

6. RUN - As the vehicle accelerates, the towline will stretch, and the tow force will build up. The longer you hold back, the stronger will be the force, and the shorter will be your takeoff run. (Just remember the tilted earth equivalent. Running before the tow force builds up is the same as starting from the top of a gently rolling hill. Waiting, corresponds to starting on the side of that hill. The longer you wait, the steeper the hillside.)

When the tow force has built up to the level you like, then you begin your takeoff run. If you start too late, then you may be shot forward very rapidly and be forced to climb faster than you intended. If you start too soon, then you may have to run too much or else hold back on the towline while running slowly.

Once you are running, the objective is still to keep your balance, you wings level, and the nose high. As in conventional flying, do not try to get into the air by jumping or by lifting your feet. Simply keep running until your feet can no longer touch the ground. If you fall, push forward on the control bar to bring the nose up.

7. FLY - As soon as your feet are lifted off the ground, pull in on the control bar to lower the nose slightly. This increases your flying speed so that a stall is less likely, and reduces your climb rate so the pull on the towline is less and the chance of breaking the weak link is less. It also slows your entrance into any wind gradient that might be present as you climb to higher flight altitudes.

At this point you have finished your takeoff and begun your flight. If you have done your job well, then you are now in full control and can do whatever you like from here on out.


Fig. 1a. Correct Tilted Earth Takeoff. 21.8 degrees
Fig. 1b. Skyting Equivalent. 21.8 degrees
Fig. 2a. Improper Skyting Takeoff.
Fig. 2b. Tilted Earth Equivalent. 21.8 degrees
Fig. 3a. Skyting Takeoff.
Fig. 3b. Tilted Earth Simulation.
Fig. 3c. Free-Flight Takeoff.
Fig. 3d. Skyting Simulation.
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1982/06-09

PLEASE SUBSCRIBE

Many of you have received this issue of SKYTING free of charge. But it costs money to publish a newsletter. Until our circulation grows large enough to employ volume printing techniques, we will have to use normal "letter copying" techniques. By using reducing techniques, we are able to get about 2 pages on one page, but it still costs about 15 cents per page to make a copy. Since 5 sheets of paper can be mailed for 20 cents, then it costs about 95 cents to copy and mail an issue of SKYTING. I simply cannot afford to send everyone $1.00 per month to keep them informed about SKYTING.

Donnell
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1982/06-10

March Wings!

Donnell,

I believe this is everything you were trying to achieve, the practical implementation of your theory.

Bob Fisher

5-19-82
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1982/06-11

Wings!

The quest for a safe tow system

Last month Wings! reported the BHGA decision to channel its efforts into towing development. Here BILL BROOKS describes the system developed with Howard Edwards at Dunstable.

The Brooks Bridle provides the answer to the problems of controlling the hang glider on the towline.

It provides:

* COMPLETE control of pitch in towing, with similar control feel and bar position to normal flight - even at high climb rates and angles.

* HIGH degree of roll control on tow, that INCREASES with line tension. You can go more than 45 degrees off line and get back on again at full tension, and launch safely 30 degrees off wind. In addition, the bridle tends to pull the pilot over to the correcting side of the control frame to give recovery. Control is again very similar to normal flight and feels more positive.

* NO modifications are required to the glider, providing it can take the towing stress (which is applied at the hang point.)

* ONLY one release catch is used - simple and reliable.

* THE system attaches to the harness and glider in about thirty minutes.

* THE bridle weighs 3lb complete with universal harness adaptor.

As you can imagine, we've been getting very excited about the system as it opens up towing for a much wider range of pilots, gliders, weather conditions, flying techniques...

* since the glider feels normal and has normal control response under tow, towing need not be the realm of experts any longer. Anyone who can basically fly can now tow, with the possibility of training people ab initio by towing on flat land.

* less critical control of the winch is required, as the pilot can now play much more of the time himself - he can vary the line tension and climb rate at will by pulling in or pushing out. This makes static winches much more feasible along with hand towing and vehicle towing (if bungee is used in the line).

* a much wider range of weather conditions is acceptable as the pilot can relieve gust loads and has full control

* new and exciting towing techniques are possible with the increased control, such as circle towing (as used by aeromodellers) to remain at the top of the line until a thermal arrives in which to release. This may also make it possible to get out much more line than can be accommodated in the launch field.

The triple action release catch has been designed with this in mind, with an auto back release at 30lb, and a half cover position front release at the same pressure.

The invention is being patented by us, and the specification describes it more fully, but the basic idea is to tow from a position near the mass centre of the combined glider and pilot system from the pilots' harness.

A spacer bar is used to let the towline tension pass either side of the pilot's shoulders, allowing a high release angle - up to almost vertically above the winch.

When the towline is released, the bridle is retracted into the nose by a light bungee, so that the pilot is unaware of it for the glide and landing.

To date we have used the system on Vortexes (Vortices?) and also the Chargus Cyclone - the type of glider you wouldn't normally dream of towing in conditions from flat calm to gusty 30 mph, with great success. At present we are busy developing static winch systems to compliment the bridle.

We genuinely believe that this device could revolutionise towing and give hang gliding a healthy boost, with X-C competitions and clubs being organized almost anywhere. It could open up the sport to many more people, and more sponsorship too.

We have been producing 50 tow bridles. They fit straight onto a Dunstable harness or other harness with a spacer bar, on to any other harness using the adaptor shown in the photo, which clamps onto the main harness webbing straps. With adapter and all the other bits including operating lever and the three-action catch is should retail for around 70 pounds.

If you think all these claims are extravagant, or even if you're just plain interested, feel free to come down and try it out.

Our thanks must go to the Thames Valley towing team with whom we went towing last summer. Their discipline of controlling the tow is very good, and obviously although the towing bridle makes things a lot simpler and safer, it's no excuse for letting those standards drop.
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Please note

ANDY Brough has carried out considerable research into safe tow launching and has submitted a detailed report to Council member Clive Smith, the association's Chief Airworthiness and Technical Officer. He has consulted Bill Brooks and Howard Edwards about their developments.

Training aspects will be vetted by Training Officer Bob Harrison.

A BHGA Tow Launch Operation Manual will be produced. Once in print details of the safest towing methods will be available to all.

PATIENCE, the Manual will be advertised in Wings! as soon as it is published. As usual a few people, included hard-pressed volunteers, have a lot of work to complete before publication is possible.

The association's Public Liability insurance policy has been negotiated so that it will be possible to cover APPROVED tow launched hang gliding in the U.K. To obtain cover, clubs will have to submit details of their equipment, operating procedures etc.

Meanwhile, if you are relatively new to the sport don't be tempted to experiment on your own. The new methods will give us safe towing. The hit-and-miss methods of the early days resulted in the deaths of dozens of pilots throughout the world.

Don't let impatience lead you to re-stage, in the name of experimentation, "lockout" and "airframe failure" accidents, usually fatal, that occurred so frequently in the past. If you MUST talk to someone contact Andy Brough on Oxford 108653 40292 or Howard Edwards and Bill Brooks on Winslow 1029 67 H 2086.

CHRIS CORSTON
SECRETARY
BHGA

The Brooks Bridle adapted for seated, supine or seated pilot.
Take-off
The release catch, retraction bungee and universal harness adaptor bar
On tow
After release - the bridle is out of the way at top of picture
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1982/07
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SKYTING NO. 3
JULY 1982
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1982/07-01

NEXT MEETING

ALL DAY FLY-IN
Saturday, July 17, 1982
8:00 a.m.
315 N. Wanda

In hopes of boosting meeting attendance, we recently decided to make our next meeting a whole day affair and announce it well in advance. By holding it on a weekend, we hope that some out-of-town-ers will be able to make it. If the weather cooperates, we hope to demonstrate the skyting system to those who have never seen it, to provide beginners with a little free instruction, to let the experienced skyters get a little air time, to experience some good hang gliding fellowship, and to go out and eat afterwards. If you want more information or need accommodations, contact me (512/592-6757) or Red (512/595-1370).
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1982/07-02

LAST MEETING

The Kingsville Skyters met at CeCe and Red's house on Tuesday, June 8. The menu was spaghetti, hot bread, and tea. I don't believe anyone went away hungry. Since no one attended the meeting who had not already gone through the beginning ground school, we decided to postpone the free ground school until a later date. One of the pilots had never seen Red's hang gliding movies, so we repeated last month's program by showing them. There were seven adults an no children present.
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1982/07-03

BRANCHING OUT

by Donnell Hewett

During the past month or so I have received numerous indications that skyting has finally begun to expand into other parts of the country. Furthermore, this expansion is primarily among experienced tow pilots - just as it should be if it to progress safely. Pilots are beginning to practice land towing in Houston, water towing in Baton Rouge, air towing in San Antonio, and possibly even developing a better release mechanism in New Mexico. Such reports are encouraging because skyting must be thoroughly evaluated by experienced pilots before it can ever become acceptable as a mode of flying.

But even more important than pilot evaluation is the fact that most of these pilots have already agreed to share their knowledge and experience with others. This attitude of mutual cooperation, open communication, and free exchange of information is what is needed if safe towing practices are ever to become a reality throughout most of the country.

This issue of SKYTING is devoted to what is hoped to be the beginning of a long period of productive communication between everyone seriously interested in improving the safety of hang glider towing. Although I am still doing most of the talking in this newsletter, I am encouraged to believe that, as more pilots gain experience with the skyting system and begin reporting their findings, their voice will grow stronger as mine grows weaker. I would, therefore, encourage anyone who in interested in skyting to subscribe to this newsletter and join us in our effort to improve towing safety.

Of course, there is a certain danger in growing too fast. As pilots explore new applications, incorporate inovative ideas, and integrate skyting into their existing tow systems, the probability of a serious accident occurring increases significantly. Although everyone I have talked with recognizes the danger of making changes in the skyting system and are proceeding with the utmost caution, the fact remains that changes are being make. If these and other changes are to be accomplished in a reasonably safe manner, then the inovator needs to adopt a set of safety guidelines. I strongly recommend that he use the same guidelines which we followed when developing the original skyting system. Our goal was simply to develop a tow system which reproduced as closely as possible the conditions of flying freely under a gravitational field.

Realizing that such a vague goal is probably impractical as a guide for most people, I recently reviewed the concepts of skyting in an attempt to identify more clearly the specific requirements which follow from such a goal. The analysis went something like this: In order for a tow system to be as safe as free flight, it must accurately mimic free flight. This means that the tow force must have exactly the same properties as the force of gravity. Specifically, the tow force must be (1) constant in direction, (2) constant in magnitude, (3) distributed proportional to the weights of the components of the glider-pilot system, and (4) applied only at the center of mass of each of the components of the glider-pilot system. And in order to safely make the transition to and from towing, the tow system must also provide (5) a gradually varying tow force, (6) a reliable release mechanism, (7) an infalible weak link, and (8) a safe learning method.

These eight requirements are called the "skyting criteria" and are explained more clearly in an article to be published this month in WHOLE AIR. It is my belief that as long as a towing system meets the skyting criteria (regardless of what specific method is used to accomplish this purpose), it will be as safe as free flight hang gliding. Therefore, before a person tries to improve the skyting system, adapt it to his needs, integrate it with another towing system, he should make sure that the final result is in agreement with all eight of the skyting criteria. To do otherwise, in my opinion, is courting disaster.
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DEAR DONNELL
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SKYTING'S CATCH 22
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1982/07-04

Dear Donnell,

Your article in Whole Air magazine is very interesting. I am currently free flying, but I want to take up towing, especially if it is as safe as you say.

Have you put in a lot of hours? Do you have the names and addresses of other people who are doing this, that I could contact?

Enclosed please find my cheque for $2.00 for "Skyting No. 1". Also, please advise me where this system is available.

Wayne Spector
Porthill, Idaho
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1982/07-05

Dear Wayne,

In your letter requesting additional information on skyting you said that you wanted to take up towing, especially if it is as safe as I say. Please remember that no flying system is safe unless it is utilized properly. As you can see from my own broken arm experience, skyting can be pushed beyond the limits of safe flying. Therefore it is important for a pilot to understand the limits of the skyting system before he tries to use it. For this reason, we do not recommend that skyting be attempted by anyone without the direct supervision of an experienced skyter. Unfortunately, there is now one outside of Kingsville, Texas, who is really qualified to give instruction in skyting. I am sorry, but this seems to be the "CATCH 22" of skyting. It is somewhat like being told, "Do not go near the water until you know how to swim." This "CATCH 22" combined with Kingsville's remote location is the main reason that skyting has not grown significantly during its three years of existance.

Now concerning your specific questions. No, I do not have a lot of hours. My current air time is only about four and a half hours. Even the skyting system, itself, is sadly lacking in flight hours. I doubt that more than fifteen total hours of flight time have been logged on the system by all the pilots who have ever used it. This is why I maintain that skyting is still an "unproven" system even though I am thoroughly convinced that it is the safest towing system in existance today. I am confident that when others gain experience with the system, they will agree with me.

As of today of today, very few people have actually tried the skyting system even though many have expressed an interest in it (primarily because of the article in WHOLE AIR). Two experienced skyters are Richard Wylde (732 S. 16'th, Kingsville, TX 78363) and Henry Wise (6327 Bellfern, Houston, TX 77035). Both have contributed to the early development of the skyting system. A third person, Chuck Burgoon (5734 Klienpeter Rd. #41, Baton Rouge, LA 70811), has not yet skyted but has recently agreed to join us in our efforts to improve towing safety.

I hope this answers your questions. Let me know if I can be of any further service.

Donnell
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SKYTING EQUIPMENT
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1982/07-06

Dear Donnell,

Really enjoyed your article in April WHOLE AIR. I guess you wrote the one in HANG GLIDING magazine a year or so ago. I enjoyed it equally as well.

Here's two bucks for "SKYTING NO. 1". After having locked out and lucked out a bunch of times, I'm anxious to give skyting a try.

I'd like to find out if you're marketing your bridle, and if not, how we can make our own. I've got a few questions about releases, toping out, etc.

If you've got a chance, give me a call "collect" and let me know about your prices and whatever. Thanks.

Chuck Burgoon
Baton Rouge, LA
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1982/07-07

Dear Chuck,

When I got your letter, I started to give you a call, but decided it would be wiser to first send you the enclosed information. I am sure it will answer some of your questions, and after you read it, we should be able to discuss your remaining questions more efficiently - as we will then have a common basis for communication.

Now concerning skyting equipment. Yes, we do sell the bridle as well as other essential components of the system. However, I do have mixed emotions about selling such equipment to persons who have not been trained in its use. Even though it is the best equipment available for use on the safest towing system in existance, it is still "prototype" and not "production" equipment. As we use it, it has been proven to be more than satisfactory, but under different circumstances, it may be found to be totally inadequate.

Therefore, we make it a policy to sell equipment only to persons who are willing to continue communicating with us. The user must be familiar with the characteristics and limitations of the equipment and understand the situations under which its use could become dangerous. We must learn what happens when the equipment is used in new application, so that we can pass this information on to others.

Listed below are the skyting components we currently have available:

BRIDLE (including releases)
- $30.00
BELT (including body ring)
- $20.00
KEEL RING (including clamps)
- $10.00
NYLON SHROUD LINE (600 ft)
- $25.00

(Shipping not included.)

Let me know if you have any questions, and I will do my best to answer them.

Donnell
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BOAT TOWING AND WINCH TOWING
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1982/07-08

Dear Donnell,

I really appreciate your letter and willingness to allow me to participate in the continued groth of skyting. I can see the great merit in skyting as well as your approach to expending its application. Therefore, I'd be more than willing to communicate feedback on our skyting experiences.

When I moved to the area a little over a year ago I was the only pilot in the area. Consiquently I went through some hair raising experiences teaching people to drive my boat and ultimately fly. Now we've got a small group of experienced tow pilots.

I've been flying for three years, foot launch, tow and motorized. I agree that skyting has tremendous potential and I'm excited to try the method in our area.

We presently boat tow with a winch and static line sometimes as well. The lakes in the area don't have any beaches, so we have to deep water start. That means "big" floats and a lot of drag.

When the weather cools off we plan on making the transition to land towing. Again, I will keep you informed on our progress. Also, rest assured that we will approach skyting with due consideration.

Enclosed is $70.00 for bridle, belt, keel ring an 6 more editions of SKYTING. Thanks again.

Chuck Burgoon
Baton Rouge, LA
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1982/07-09

Dear Chuck,

Thank you for joining us in our efforts to improve the safety of hang glider towing. I am particularly pleased to have you working with us because you are the first person outside of Texas to join us in this effort, you are the first person to accept the responsibility of learning to skyte on your own (without the benefit of personalized instruction), you are the first practicing tow pilot to become involved in skyting research who has the facilities to adopt skyting to boat towing and to winch towing. In short, you are the first person willing and able to help us bridge the wide gap between our own unique towing method and the more conventional towing methods commonly used today.

Enclosed you will find the items you ordered. As I mentioned before, these are prototype, and not production, models. Since we do not have a set of instructions for those items, I shall try to briefly explain how each of them is used in the space below.

BRIDLE- As you can see, the bridle is essentially the same as that illustrated in SKYTING NO. 1, page 11, Fig. 9. It is installed as shown in that figure and used as described in SKYTING NO. 1.

BELT- The belt has been shipped unassembled in order to save space. The figure at the right illustrates how to assemble it and use it. Once you have determined the length you want it to be, simply cut off the unused portion. You may find it necessary to "rethread" the belt every time you use it with certain harnesses. (And it may be that it will not work with some harnesses.) Since we do not use the belt ourselves (our body rings are sewn permanently to our harnesses). Our experience with the belt is somewhat limited. Never-the-less, I believe the design to be a good one even if it is simple.

KEEL RING- The figure at the right illustrates how the keel ring is attached to the keel of the hang glider. We place ours about 16 inches in front of the pilot's hang point so the keel latch is out of the way during take-off and while flying. Make sure the clamps are tight so the unit does not slip forward during flight.

SKYTING SUBSCRIPTION- I have decided to make the SKYTING magazine more of a newsletter and publish it monthly in order to better meet the needs of those currently practicing skyting. Therefore, instead of receiving 6 issues of SKYTING at unspecified intervals, you will be receiving 12 issues monthly, through June 1983.

COMMENTS ON SAFETY- I have long been concerned about the dangers of trying to integrate skyting with other towing systems. The two philosophies are simply so different that trying to mix them is almost certain to violate the safety requirements of one, the other, or both. But after two years of unsuccessfully promoting our particular skyting system, I have come to the realization that some form of integration may be necessary. If this integration is to be accomplished safely, then it is obvious that some kind of guidelines must be established. As a result, during the last few months, I have been trying to identify those elements of skyting which are absolutely essential for safe towing. The result of this effort is to be published in the July/August 1982 issue of WHOLE AIR and is called the "Skyting Criteria." It is my belief that as long as a towing system meets all eight of these criteria, then it will be just as safe as free-flight hang gliding, regardless of what particular methods are used to meet those requirements. These criteria are listed below, along with suggestions as to how you might go about meeting them.

(1) CONSTANT DIRECTION- The easiest way to guarantee that the direction of the towing force remains constant is to use a long towline - the longer the better. Since you are experienced towers, I assume you already use a towline of 500 ft or more. If this is true, then your current towing practices already meet this requirement.

(2) CONSTANT TENSION- Although we use dynamic control of the tow vehicle's speed to maintain constant tension, it is my belief that a good winch would do the job better. Since you have a winch, I recommend that you use it. The setting should be around 100 to 150 pounds of tension - probably the same as you have been using in the past. In any case, never let the tension exceed about 200 pounds or the pilot may find it impossible to release himself in an emergency. (The latches become harder to release as the tension increases.)

(3) PROPORTIONAL DISTRIBUTION- The skyting bridle solves the problem of distributing the tow forces approximately proportional to the masses of the glider-pilot components.

(4) ATTACHMENT POINTS- As mentioned in SKYTING NO. 1, the keel ring and the body ring should be located as close as possible to the center of masses of the glider and pilot, respectively. Do not forget while flying that no part of the bridle should touch any other part of the glider-pilot system.

(5) SLOW TRANSITIONS- If at all possible, you should you use an elastic towline long enough to provide at least 30 ft of stretch in order to guarantee that the towline tension always varies slowly and that the transition between towing and free-flight will always be gradual. Abrupt changes in the towline tension are a gross violation of criterion number 2 listed above. There is no doubt that abrupt changes produce situations significantly more dangerous than that of normal free-flight hang gliding.

(6) RELIABLE RELEASE- We have found the releases supplied with our bridle to be quite reliable as long as the towline tension is not excessive. (And since our weak link prevents excessive tensions, we have had no trouble with them at all.) However, certain pilots in Florida have expressed concern about the quality and potential reliability of our bridle-release system. Although I agree that a better release could be designed and built, I still know of no better design which is currently available.

(7) WEAK LINK- I am afraid that you have a problem here. Skyting requires the use of an infalible weak link, but a deep water start almost certainly requires a temporary violation of the weak link limit. Apparently deep water starts are going to require you to use a weak link that can fail. I don't like it, but it appears that you may have to continue using the same "weak link" you have in the past - the best spotter you can find to operate the safety release. If you can think of a better solution, I would like to hear it.

(8) SAFE LEARNING METHOD- The safest way for anyone to learn to skyte would be to come down to Kingsville and obtain personalized instruction on the skyting system as we use it. Since this would seem to be impossible in your situation, then you should adopt skyting's gradual advancement plan as described in SKYTING NO. 1. If you take things slowly, mastering each minor change before making another, then in spite of your mistakes, you should eventually be able to reach your goal in a reasonably save manner.

COMMUNICATION- As you gain experience with the skyting system, please let us know what you find out. To begin with, I would like to have your personal opinions about each of these pieces of prototype equipment and an evaluation of the performance of the system as a whole. A comparison of skyting with your current system would be particularly enlightening. Do you have any suggestions for improvements? How well does the equipment hold up when water towing? Can the skyting bridle handle the deep water starts properly? Etc. (Anything you learn will be of benefit to others, even if you only confirm what we already have discovered.)

By the way, in your evaluations, please do not withhold criticism for fear of offending me- the lives of future pilots are more important than the feelings of an individual. If something is wrong with our system, it needs to be corrected, and if anything is suspicious, it needs to be investigated. Thank you for your interest and involvement in the effort of improving towing safety.

Donnell
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AIR TOWING
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1982/07-10

Dear Donnell,

I would like to purchase one of your hang glider tow bridle/release systems. I read about the system in Hang Glider magazine last year, but did not have the opportunity to see one until two weeks ago at the Regional Competition at Packsaddle.

I am a hang IV pilot, 250 hours, international competition, etc., etc., ... the point being - I shall approach the use of your system with the caution and respect it deserves. Please be advised that I am looking at a number of concepts with the goal of developing a reliable air tow technique. Your guidance will be greatfully accepted.

Enclosed is $30.00 which I understand should suffice as payment. Thanks.

James T. Collins
San Antonio, TX
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1982/07-11

Dear James,

I am sending you the Skyting bridle system you requested even though we do not normally sell skyting equipment to pilots who have not agreed to maintain communication with us. You should understand that the equipment we use is still "prototype" and not "production" models. Although it is the best equipment known to be available, and although it has served us well during the three years we have been using it, it has not really been tested under all conceivable conditions and certain refinements may be in order before it is ready to be sold to the general public. We expect those who use the equipment to keep themselves informed as to its suitability under various conditions, and we expect them to keep us informed about any problems they discover when the equipment is used in new situations. Therefore, I am sending you this equipment under the assumption that you will agree to maintain communications.

Actually, I hope that you will do more than simply communicate with us from time to time. For several years now, we have been looking for someone within driving distance who is (1) an accomplished pilot experienced with towing, (2) interested in trying out our towing system, and (3) willing to join us in our efforts to improve towing safety. I hope you are that person.

Chuck Burgoon, of Baton Rouge, LA, has agreed to work with us in this effort. He has the facilities to adapt the skyting technique to boat towing and winch towing. If you would be willing to share your ultralight towing experiences with us, it would complement the work he and I are doing in different areas of towing. By working together, we can each learn more, faster, and safer than we could possibly learn by working separately. Furthermore, there are others besides ourselves who could benefit from what we learn. Let me know if you are interested.

In your letter you mention your goal of "developing a reliable air tow technique". By this, I assume that you intend to tow behind an ultralight aircraft, much the way conventional gliders tow behind airplanes. Whether this is your intent or not, please remember that it takes more than a bridle to make a tow system safe. In an article "The Skyting Criteria", scheduled to appear in the July/August issue of WHOLE AIR magazine, I explained why I believe that there are eight essential criteria which a towing system must meet before it can be considered really safe. These criteria are listed below along with suggestions as to how you might go about meeting them while towing behind an ultralight aircraft.

(1) CONSTANT DIRECTION- When towing behind an ultralight aircraft, the hang glider should always remain directly behind but slightly above the ultralight. Under these conditions, the glider will do very little manouvering. Therefore, the towline will not have to be as long as is normally required when land towing or water towing where significant manouvers are performed. Never-the-less, I would still recommend a towline at least 300 ft long as a safety factor so that wind gusts do not cause tracking difficulties.

(2) CONSTANT TENSION- As long as the ultralight flies at a comfortable air speed for the glider, then an elastic towline should be adequate to guarantee essentially constant tension while under tow. The towline should be capable of stretching at least 30 ft in order to accommodate typical wind gusts. As a starter, I would suggest that you try an indicated air speed of 27 mph and use about 300 ft of nylon parachute shroud line. (A "stronger" tow rope would have to be considerably longer to give the desired tretch, and a rope without this stretch would violate the constant tension criterion in gusty conditions.)

(3) UNIFORM DISTRIBUTION- The skyting bridle solves the problem of distributing the tow force proportional to the way gravity distributes the weight.

(4) APPLICATION POINTS- Here you must not only consider the glider but also the ultralight aircraft. In the case of the glider-pilot system, attach the keel ring and body ring as described in SKYTING NO.1. Always remember while flying that the bridle should never come into contact with the control bar or the flying wires. Although we fly with the body line beneath the control bar, you should let it pass through the control bar. This is because your tow angle should never get as great as ours. If it does, there is a good chance you will force the ultralight into an uncontrolled dive. For similar reasons, the other end of the towline should be attached to the ultralight so the line of action of the force passes through the center of mass of the ultralight. Otherwise a strong pull on the towline could force the ultralight out of control.

(5) SLOW TRANSITIONS- If you use a towline with plenty of stretch, you will automatically guarantee that the transition to and from towing will be gradual.

(6) RELIABLE RELEASES- You will need a reliable release on both ends of the towline. The skyting bridle contains the releases for the glider's end. You will have to design a good release for the ultralight's end. I suspect the release you used in your previous towing experience would suffice. Just remember, both the tow pilot and the glider pilot must be able to terminate the flight if either one finds himself in a dangerous situation. Normally, the glider should release first. If the tow pilot releases first, there is a possibility that the towline might fly back and become tangled with the glider.

(7) WEAK LINK- In my opinion a weak link is absolutely essential for air-to-air towing. It is impossible for either the tow pilot or the glider pilot to concentrate upon flying their respective aircraft and also serve as effectively as a safety man. The glider pilot could come closest to doing both jobs, but that leaves no one to "bail him out" in an emergency situation. In fact, the glider pilot could find it impossible to release himself if the towline tension ever becomes excessive. This is because the skyting latches become harder to release as towline tension increases. Only an infalible weak link can guarantee that such a potentially fatal situation never occurs. As mentioned in SKYTING NO.1, I recommend a loop of nylon twine of the proper size. (We use No. 18 braided nylon twing.) The weak link should be placed between the towline and the leader, and a 3 ft drag chute should be placed on the towline end to prevent the stretched towline from shooting toward the ultralight and possibly fouling the propeller. The drag chute should have little effect upon the ultralight (assuming the ultralight has enough power to tow the hang glider in the first place.)

(8) SAFE LEARNING METHODS- You have already said that you would approach the use of this system with the caution and respect that it deserves. As a Hang IV pilot, I am sure that you have the maturity and judgement to oversee your own progress. Here I shall only remind you of skyting's gradual advancement policy: Thouroughly master each little step of the way before proceeding to the next.

Let me know how things go and what I can do to help.

Donnell
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PLEASE SUBSCRIBE
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1982/08
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SKYTING NO. 4
AUGUST 1982
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1982/08-01

COMETS AND COMMENTS

Two important milestones have been reached this month in regards to the advancement of the skyting system: (1) double surface gliders have been flown on the skyting system, and (2) someone besides myself has started sharing his own skyting experiences.

On July 17, 1982, in Kingsville, TX, James T. Collins of San Antonio skyted his Comet 135 to approximately 500 ft on several flights. (See the Kingsville Skyt-in article in this issue of SKYTING.) Shortly thereafter, through a telephone conversation, I learned that Dennis Owen of Rock Hill, MO, had skyted his Comet for the first time on the same date. And through another conversation (with yet another person) I gathered the impression that Chuck Burgoon of Baton Rouge, LA, also skyted for the first time on that date. If this is true, and if he also flew a double surfaced glider, then it would appear that double surfaced gliders were flown for the first time by three different pilots, in three different states, all on the same date. I find this a rather remarkable coincidence, particularly since I have been trying for over two years to find even one experienced pilot with a high performance glider who was willing to tow it on the skyting system.

But whether all three or just two of these pilots flew their high performance gliders for the first time on that date, the fact remains that experienced pilots are beginning to fly with the skyting system. We are looking forward to reading some reports of their initial impressions. We are also interested in hearing some follow-up reports written after they have gained more experience on the system.

In this respect, I think that it is fitting that this issue of SKYTING not only reports the fact that others have started flying with the skyting system, but that it also contains the first report of someone besides myself who has used the skyting system, Henry Wise, of Houston, TX, has been kind enough to share with us some of his comments on the skyting system. (See Some Thoughts On Towing in this issue of SKYTING.)

You will recall, from SKYTING NO. 1, that Henry was responsible for calling together the first group of hang glider pilots in the Corpus Christi area of Texas. Henry even loaned us the use of his glider for our first flights off the sand dunes of Padre Island three years ago. It was these puny, yet exhausting flights that convinced me that towing had to be the answer to free flights in the flat lands.

At first Henry was very skeptical about any form of "self-taught towing" but after nine months of watching our flying progress, he decided to try the skyting system, himself. He was our first serious "student", and learned to skyte to level 5 (about 50 ft ground clearance) before moving to Houston. Since that time he has also been instrumental in introducing the skyting system to the Houston hang gliding community.

In his article, Henry points out several things about skyting that I have failed to mention. This is an example of why we need more than one person's view of the skyting system. Thank you, Henry, for your contribution to skyting.
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1982/08-02

THE KINGSVILLE SKYTE-IN

by Donnell Hewett

On July 17, 1982, Henry and Susan Wise (from Houston) and James T. Collins (from San Antonio) joined the local Kingsville Skyters (Richard "Red" Wylde; Eddie and Kathy Bolls; and Donnell, Helen, Tahnya, and Tammi Hewett) for a fun-filled day of flying, food, and fellowship. The weather was typical for a summer day in South Texas: partly cloudy, with winds southeast at 10 to 15 mph in the morning and 15 to 20 mph in the afternoon (at 45 degrees across our N-S runway).

Since I was the skyting "expert", I went first and demonstrated clearly to the others the proper way not to fly. During my first three flights, I broke the weak link, got tangled up with my newly installed stirrup system, hooked in with the stirrup improperly positioned, almost ground looped while landing, bent a deflexor, ripped my pants while landing too fast on my knees, and flew with the glider out of proper trim because of an inadequate preflight inspection. I guess my poor performance did demonstrate how forgiving the skyting tow system is, but it also demonstrated that I need to get my act back together.

Henry was the next to fly and made two flights. On his last he broke a weak link and hit a wind gust at about 10 ft while landing, but he was still able to make a 360 and land successifully near takeoff.

J.T. was the third to fly. Although he had had considerable hang gliding experience and some towing experience, this was his first time to fly with the skyting system. We decided to slightly "bend" our "gradual advancement rule" because of the danger of flying close to the ground under these gusty wind conditions. Instead of making several short hops, we decided to continue towing at a very gentle climb rate as long as J.T. kept his glider under complete control. At the first sign of trouble, we agreed to abort the flight.

On his first flight he gradually towed to 300 ft, released, and flew back to takeoff. (He also made a hard landing because of the gusty conditions.) On his next two flights he maxed out at 500 to 550 ft on our 600 ft line. (This is the longest towline we can use at the airport because the manager does not want us to interfere in any way with the normal airport trafic.)

After J.T. flew, I made three more flights and then Red (who had been working all morning) arrived and made two flights, breaking the weak link on the last. By this time the winds were approaching kiting conditions and everyone but J.T. elected not to fly again. (Eddie, a beginner, never was able to fly because of the strong conditions.) After J.T. made three more flights, we called it a day.

On the first of these last three flights, J.T. broke the weak link for his first time. (We were driving too fast for the wind gradient.) On each of the next two flights, we towed J.T. through the wind gradient and then stopped the vehicle while he climbed on up to 500 ft and hovered there for four and a half minutes. The first of these kiting flights was terminated when he broke the weak link. Since he was almost directly overhead when the weak link broke, we assume that a thermal was providing the strong lift which broke it. There is little doubt that if he had not been restricted to flying only over the airport's auxiliary runway, J.T. could have cored the thermal and made the first skyting-launched cross country flight right then and there.

Watching J.T. flying his Comet 135 on the skyting system was very impressive - undoubetedly the best example of hang gliding ever performed over the flat lands of South Texas. He certainly demonstrated that there is no problem in teaching experienced pilots to fly modern, high-performance, double surfaced hang gliders on the skyting system. We also found that such a glider could climb at 600 to 1000 fpm on the skyting system without breaking the weak link.

Performance and handling were essentially the same while towing as when free flying. And breaking the weak link (standard #18 nylon twine) was no more of a problem with a high performance glider than with any other type of glider we have skyted.

All of this, of course, was to be expected, but - you know - it is always nice to have your expectations fulfilled.
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1982/08-03

SOME THOUGHTS ON TOWING

by Henry Wise

After considerable thought, rehashing with people, and some towing experience, I've come to several conclusions on skyting techniques. These conclusions are in several areas not previously discussed in any detail.

The first point concerns takeoff. Everyone knows that all you do is point the nose straight up, signal the vehicle to move, and you're off. Well, it's a little more involved than that. What happens if you're five or ten feet in the air and you find yourself suddenly moving sideways. It may be due to a sudden crosswind or even a stalled glider. Stalled glider?! How do you stall a glider that's under tow? Well, the easiest way is for the vehicle to change gears (if it's a standard transmission) just as you take off. Your kite will act as a drag chute on the vehicle and slow its speed.

In the case of the cross wind, you simply initiate a correcting turn, but for a stalled glider the correction should be different, shouldn't it? If you were free flying and stalled, you'd get on the high side of the control bar and pull in. Use this procedure under tow and you'll recover, but at the cost of a slack tow line. The vehicle will then have to gain an extra amount of speed just to catch up with your extra speed, and when it does, you will receive an uncomfortable jerk as the line tightens. A better recovery would be to get on the high side of the control bar and push out. Push out?! Why that should cause both wings to stall! True, but there's a catch. The vehicle can easily out accelerate you. Therefore, it's to your advantage to keep the towline tight. Not only will both wings be flying in no time (remember, the vehicle is now in a higher gear and is accelerating) but you probably will find out that you've over corrected!

Over correcting. Even an experienced pilot may have this problem the first few times he is skyting. Why is it that the Hewett bridle seems to make your glider more roll and pitch sensitive? The answer lies in the fact that one of the points of attachment is on the pilot. The net effect is to increase the pilot's weight on the glider. When you move your body, not only are you applying a force equal to your body weight, but also added to it is 2/3 of the tension on the glider. For example, if a pilot weighs 180 lbs and is towing at 120 lbs, the net effect is to be flying with a weight of 180 + 2/3 (120) = 260 lbs! No wonder you're over controling!

OK, you've gotten off the ground safely with no problems. Next question: What is the proper speed to fly at? Obviously, it should be your best sink rate. That is the speed you fly while thermalling, so why not here. Remember, however, that the further forward on the keel that you place the upper bridle attachment point, the more you'll have to push out to achieve that speed.

Suppose you're climbing out nicely when the weak link breaks. What do you do? Pull in! If you react quickly enough, little or no stall will occur. Part of the reason for no stalling is because you were already flying with only a moderately high nose. The rest of the reason is because you were also climbing at a speed higher than stall speed. When the weak link broke you began to lose speed, but you realized this and pulled in, which prevented a severe stall. You should always fly expecting the weak link to break. This will help you react instantly if it ever should.

Once normal flying speed is reestablished, determine if you have enough time to extricate yourself from that tangled mass of rope. If you do, then by all means liberate yourself and have a nice flight. If you don't, then once again, forget about the rope and get ready to land.

A word of caution. Beware of where you place the weak link. If you place it where the tow line and bridle meet, you may find that, after the weak link breaks, you've now got a lovely hole in that beautiful sail you just bought. What happened? Well the bridle is made of nylon, which stretches like crazy. When the weak link broke, the nylon acted like a rubber band and went zooming away. If you were at a high angle to the tow line, and the bridle missed your head (another reason to wear helmets!), it probably went through the sail. This has happened before. What can be done to prevent this? I use 100 ft of 3/8 inch braided polypropylene ski rope attached directly to the bridle. The other end is then attached to the tow line via a weak link. The polypropylene rope hardly stretches and so acts as a drag on the bridle when the weak link breaks. I have broken my weak link with this arrangement and didn't even get the bridle to touch my head.

A personal note to end on. I've watched hang gliding progress through the years, starting with the old standards. Advances have been made and the sport has finally come into its own. Ultralights were developed as an offspring and are just beginning to flower. Towing has long been treated as a naughty child by the two, but at long last it too has found its way and will reach fruition in about five more years. Don, thanks for showing us all the way.
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DEAR DONNELL
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SKYTING COMPONENTS
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1982/08-04

Dear Donnell,

Thank you for sending me the information on skyting and for the paper, which seems to be an excellent analysis of the forces involved in towing. I believe from a theoretical point of view your system will work. I am an experienced Hang Glider pilot who wished to tow over water, the only problem being I live in the boondocks and it is difficult for me to find all the parts for your system. Would it be possible for me to purchase the weak link, the two quick release mechanisms and the three rings from you? I am sure I could build everything else, although if you have a tension gauge, that would also be helpful. I would be happy to reimburse you for your time involved in gathering these things together. This would possibly eliminate the problems with the towing system, if the proper equipment was used. I will of course use the gradual advancement approach, which I believe should be applied to all hang gliding learning situations.

As I said before, I am very impressed with the thoroughness of your approach to this technique. Thank you for your interest in this matter.

Wayne Spector
Porthill, Idaho
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1982/08-05

Dear Wayne,

Thank you for your words of encouragement and for the interest you have expressed in our skyting system. Since your situation is similar to that of others who have decided to try skyting on their own, I suggest that you bring yourself up to date with the questions, answers, problems, solutions, and suggestions which appear in SKYTING NO. 2 and 3.

There you will see that we do sell skyting components are still classed as "prototype" and are generally sold only to persons willing to maintain communication with us. Specifically, we want those using our equipment to subscribe to SKYTING in order to keep themselves informed about the latest skyting developments, and we want them to keep us informed about their progress so we can pass this information on to others. We are particularly interested in learning about their problems, solutions, and suggestions.

PRICE OF COMPONENTS

Now concerning the skyting components you requested, I could sell you the following items for the following prices:

Slip rings (steel)
- $02.00 each
Slip rings (brass)
- $03.00 each
Body ring
- $03.00 each
Latches
- $08.00 each
Latch sleeve tubing
- $03.00 /foot
Nylon bridle rope
- $00.25 /foot
Auto-release line
- $00.10 /foot
Weak link twine
- $05.00 /spool
Bridle (complete)
- $30.00
Skyting belt
- $20.00
Keel ring (kit)
- $10.00

Some of these items are so hard to obtain that I have not yet found a permanent supplier for them. Others are so common that you would do well to save money by purchasing them locally. My prices reflect the effort I expend in locating the item, driving down to pick it up, paying retail price, packaging it up, and taking it to the post office. I have not included shipping costs because it varies unpredictably from case to case.

SKYTING BRIDLE

In your letter you indicated that you intended to construct your own skyting bridle from the individual components. Although there is nothing inherently wrong about doing this, I would recommend that you purchase your first skyting bridle system complete and already assembled. In this manner you are able to begin at the current state of the art and proceed from there.

BODY RING

The best method of attaching the body ring is to sew it directly onto your harness. I recommend that you use a body ring shaped like the one illustrated below:

Attach it to your harness with a piece of nylon webbing about 8 inches long and of the same color as your harness. It should be sewn (either by hand or by machine) to your main support strap as shown in the illustrations below:

If you prefer a non-permanent body ring attachment or one that can be transfered from pilot to pilot, then I recommend that you use the body belt illustrated in SKYTING NO. 3.

KEEL RING

In the case of a keel ring, I prefer the design illustrated in SKYTING NO. 3 over that illustrated in SKYTING NO. 1.

WEAK LINK

I am a little surprised that you cannot find the No. 18 nylon twine even in the "boondocks" where you live. This twine is very common at stores that sell fishing supplies. It should be used for trot line fishing and comes in both braided and twisted form. We prefer the braided line because the ends do not unravel as fast, but the twisted form is easier to locate and functions just as well as a weak link. I cannot be certain that No. 18 nylon twine is exactly the size you will need for your weak link because other pilots have not yet confirmed the fact that it works as well for them as it has for us. You can, of course, alter the actual breaking strength but using more or fewer strands and by using different knots. For example, a simple square not will weaken the line considerably, while some other knots will retain almost the full strength of the line. Personally, I like the knot illustrated in the figure below. It is both strong and easy to tie (after a little practice).

TENSION GAUGE

I am currently in the process of writing an article on our tension gauge for SKYTING which you may wish to read before making any kind of decision. Let me say here that my source for springs is the local automobile junk yard. The springs are rusty and the price varies from visit to visit. If you want me to supply you with one, I would have to bill you according to my actual costs. (As a ball park figure, I suspect the cost to you would be between $10.00 and $20.00 including postage.)

I hope this answers your questions. If there are any other components you cannot find, or if there is any other way I can be of service, please let me know and I will do what I can to help you.

Donnell
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1982/08-06

THE TENSION GAUGE AND ITS USE

by Donnell Hewett

In order for a towing system to be really safe it must meet a certain set of specific criteria, called the "skyting criteria." (See SKYTING NO. 3.) One of these criterion is the requirement that the towline tension remains always constant while the glider is under tow. There are two methods commonly used to accomplish this goal. The most elegant method consists of a well designed tow winch, while the least expensive utilizes "dynamic control".

Dynamic control, you will recall from SKYTING NO. 1, consists of regulating towline tension through a combination of towline stretch and vehicle speed modification. We have found this method to be quite effective in keeping the towline tension constant to within approximately +/- 25 pounds under almost all reasonable flight conditions. However, there are certain flight conditions for which dynamic control has been proven to be inadequate. Examples of such conditions would include severe turbulence and excessive flight manouvers.

The only major problems we have encountered with dynamic control have been associated with the tension gauge. It should be obvious that an accurate and reliable tension gauge is absolutely essential to the proper implementation of dynamic control. The vehicle driver simply must know what the towline tension is and what it is doing in order to adjust the vehicle's speed accordingly. Unfortunately, we have never found a tension gauge which really does the job right.

In the past, we have tried various tension indicators including towline sag, engine strain, and towline "singing", but these are only crude indicators. The tension gauge discussed in SKYTING NO. 1 was a great improvement, but it was difficult to install on the vehicle, rubbed against the paint of the vehicle, and made it difficult for the driver to enter or exit the vehicle.

For these and other reasons, we have slightly modified the design. Our current tension gauge is illustrated below:

As you can see, we are still using the old junked hood spring (off of a truck or large automobile) as our tension measuring device. But the position of this spring has been moved to the rear of the vehicle and the sleeve has been removed. One end of the spring is tied to the trailer hitch (or bumper) of the vehicle and the other end is attached to the bottom of the towline. A taut line is then stretched between the moving end of the spring and the hand of the driver. This line passes through the spring and around, over, or through the vehicle as needed. A knot is tied in the driver's end of the taut line and adjusted so that when the line is pulled tight, the know is just touching a convenient position on the window frame of the driver's door. In order to keep the taut line handy, the end beyond the knot is tied to the rear view mirror on the driver's door and adjusted loose enough to permit easy entry but tight enough to prevent it from sagging and becoming tangled with the wheel of the vehicle.

The principle of operation of the gauge is as follows: As the towline tension varies, the spring stretches accordingly. As the spring stretches, the taut line translates this movement to the knot located in the driver's hand. The amount of movement of the knot is a direct indication of the stretch of the spring and, therefore, the tension in the towline.

This design is easy to install, causes no appreciable wear on the vehicle, allows the driver to enter and exit the vehicle, is compact when stored, leaves the driver's eyes free to drive the vehicle (instead of requiring him to watch a gauge), is low cost, is easy to construct, and is simple to operate and understand. Unfortunately, the system has neither the quality, the accuracy, nor the reliability which one would prefer.

In the first place, there is no dial which specifies the true, absolute value of the towline tension. The driver must develop a "feel" for what the tension is doing, how strong a pull is needed in a given situation, and when the weak link is about to break.

In the second place, there is so much "play" in the taut line that when the tension varies, or when the tow angle (angle of the spring) varies, then the knot does not consistantly indicate the correct reading.

And finally, there have been times when the towline tension increased to the weak link breaking point without any such indication by the knot.

For the above reasons, several of those with whom I fly are less than satisfied with this design. From the operational point of view, they prefer the original design illustrated in SKYTING NO. 1.

Never-the-less, I like the design. When I am the driver, I use it. Personally, I have found our tension gauge to be the fastest and most reliable indicator we are using which is able to inform me what is happening on the towline. Almost without fail I find myself already responding to the signal from the tension gauge before the spotter tells me what to do. By the movement of the knot in the taut line, I can tell when I am going to fast, when I am going too slow, when the glider hits a gust of wind, when the pilot is climbing too fast, when the weak link is about to break, when the weak link does break, and when the pilot releases from tow.

But there are certain "tricks" I use when driving with the tension gauge which seem to help improve its performance.

(1) I always check the taut line (from spring to door) before climbing into the driver's seat. Sometimes the line is improperly positioned or partially snagged on something. Obviously such irregularities must be eliminated before the gauge can operate properly.

(2) After shutting the door, I check to see that the line is not caught in the door. The knot should just reach the window frame when the line is pulled tight

(3) When using a standard transmission, I hold the line loosely in my left hand while grasping the stearing wheel. This frees my right hand for shifting gears. I always make sure the line is sufficiently taut to prevent it from sagging down and becoming tangled with the vehicle's wheels.

(4) Before giving the "vehicle ready" signal, I check once more to make sure that when the line is really taut the indicator knot is just able to reach the correct position on the window frame. This is probably the most important thing to remember when using this type of tension gauge: THE TAUT LINE MUST BE TAUT IN ORDER FOR THE TENSION GAUGE TO READ PROPERLY.

Remember that the tension gauge is designed to read forces on the order of 100 pounds or more, so it is possible to pull on the taut line with forces as large as 10 pounds or so without effecting the result of a tension reading. But this same 10 pound pull will have a significant effect upon removing any slack or overcoming any friction which might be present in the taut line, itself.

I cannot be certain, but I believe that the primary reason others have found this tension gauge design to be unsatisfactory is that they did not remove all of the slack from the line before using it or keep adequate tension on the line while using it.

(5) During the actual takeoff, I normally ignore the tension gauge. If I am driving with a standard transmission, it is impossible to use the gauge while shifting gears. But even with an automatic transmission, I prefer to use the rear view mirror as my primary source of information. I watch the pilot and the glider for any signs of trouble, and try to react accordingly to the particular flight situation. In my opinion, this is a more positive indicator than any tension gauge as to what is happening.

However, once the vehicle is moving, I have to watch where I am going, so as soon as possible after takeoff, I begin using the tension gauge. From time to time I do glance at the glider through the rear view mirror. I also glance at the vehicle's speedometer, and at the air speed indicator. And naturally I listen to engine noises, towline singing, and information supplied by the spotter. But my primary source of information comes from the tension gauge.

(6) Once the tension gauge is in operation, I try to maintain the tension requested by the pilot for that particular flight. If the pilot made no specific request, then I assume he wants to climb with about 100 pounds of tension. For our system, this means that the knot should be about 1 inch from the window frame. (It takes about 60 pounds to begin stretching our spring, and the spring constant is about 50 pounds per inch.) If the knot ever gets to the 2 inch position, I know there is a slight chance the weak link is almost certain to break.

Under normal flight conditions it is reasonably easy to keep the knot at the 1 inch position so that the tension remains constant at 100 pounds. But sometimes I find myself overcorrecting and oscillating between too much and too little speed. Actually, I believe the pilot is contributing to this overcorrecting phenomenon. As the tension varies from the optimum position, both he and I make corrections (the pilot by pulling in or pushing out, and I by speeding up or slowing down). Either correction would probably be adequate by itself, but together they are too much. Whenever I recognize these oscillations due to such overcorrections, I attempt to drive the vehicle at the average speed of the oscillations and temporarily ignore the input of the tension gauge (unless, of course, it starts approaching the weak link breaking point).

By the way, if I am the pilot, I make no attempt to regulate my own towline tension. In the first place, tension regulation is the driver's responsibility. And in the second place, such an attempt is futile. If I try to increase the tension by slowing down, the driver will also slow down as soon as he recognizes the change in tension. Similarly, if I try to speed up to relieve the tension, the driver will also speed up, trying to keep it constant. If the towline tension is consistantly too low or too high, I either signal the driver to change speeds or else go ahead and fly at the tension setting that is present.

The above paragraph assumes that the air is smooth. If gusty conditions prevail, then as a pilot I do attempt to help the driver keep the tension constant. Well, actually, my goal is not to keep the towline tension constant, but rather to keep my own speed and climb rate constant. If I can do this, then the driver can keep tension constant.

Specifically, when a wind gust tries to slow me down or make me climb hard, I pull in on the control bar to speed up and/or reduce my climb rate. (And vice versa.) While I am doing this, the towline tension increases slightly (which only helps me accomplish my goal) and the vehicle starts slowing down. But because I can usually feel the gust before the driver can sense any change in towline tension, I can reduce the effect of wind gusts considerably and make it easier for the driver to do his job.

Of course, if the "gust" is prolonged (as, for example, when entering a wind shear or a thermal) there is little I can do to modify the towline tension. I can pull in to increase my speed and reduce my climb rate, but if the vehicle does not slow down, I will have to continue flying in this "untrimmed" configuration. Under these conditions, I slowly let the control bar return to its normal position. This will let the tension gradually increase so the driver has time to respond. If the driver does not respond as he should, then I either signal him to slow down or else get ready for the weak link to break. Either of these alternatives is preferable to continuing a prolonged flight with the control bar "tucked to my knees."

From the above discussion, you can see that I am reasonably happy with our current tension gauge design and believe that dynamic control of towline tension shows real promise for providing low cost tension regulation. Never-the-less, there is still room for improvement in both tension gauge design and in dynamic control flying techniques.
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1982/08-07

FIRST REPORTED EQUIPMENT FAILURE

The first reported equipment failure of a piece of skyting equipment was made by Dennis Owen of Rock Hill, MO. Since the report was made over the telephone and since I have a very poor memory, then I may not have all the facts straight, but I believe that while Dennis and his flying buddies were skyting for the first time, they found that one of the latches released prematurely.

I do not know exactly why the unit failed to hold properly, but apparently they were able to get it working by filing off a portion of the casting.

The unit seemed to be working when I tested it before shipment, but I have had to reject other latches because of poor quality from my supplier. Obviously a better latch and/or higher quality control is needed in this area.

Dennis and his friends are looking into the possibility of using a "three-ring release" on the skyting bridle. This release has apparently been proven to be reliable in certain parachute applications. If it can be adapted to skyting, then it may be the answer to the reliable release problem.

I am certainly glad that no one was injured because of the malfunction. It is fortunate that the failure was a failure to hold, and not a failure to release. In the latter case, things could have been bad.

This incident should serve to remind us of the importance of checking the release mechanism for proper operation before every flight. Just because the release worked before is no guarantee that it will work this time.
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1982/09
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SKYTING NO. 5
SEPTEMBER 1982
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1982/09-01

SKYTING STALL RECOVERY TECHNIQUES

by Donnell Hewett

In last month's issue of SKYTING, Henry Wise correctly pointed out that the stall recovery technique used in skyting can, in general, be quite different from that used in free flight. He also pointed out that this subject has been neglected in the literature and went on to discuss the topic further, himself. This article is a more extensive discussion of this important subject.

STALL PREVENTION

In general, stalls are the result of flying a glider at too high an angle of attack. In practice, this means that stalls can result from flying too slow, from excessive maneuvers (such as tight turns or strong pull-ups), and from strong wind gusts. The procedure for preventing stalls, therefore, is quite straightforward: (1) NEVER ATTEMPT TO FLY THE GLIDER BELOW ITS MINIMUM FLYING SPEED, (2) NEVER PERFORM EXCESSIVE MANEUVERS WHILE SKYTING, and (3) NEVER SKYTE IN STRONG GUSTY CONDITIONS.

Since excessive maneuvers and strong wind gusts are normally avoided when skyting, almost all skyting stalls are the result of towing too slow. As long as the vehicle is moving faster than stall speed, there is little tendency to stall the glider, but if the vehicle slows down below stall speed (or never attains flying speed) there is a strong temptation for the pilot to slow accordingly and a stall results. The pilot should be aware of this temptation and learn to resist it.

STALL RECOVER METHODS

From the preceding discussion, it should be apparent that stalling should be no more of a problem when skyting than when free flying. But just as stalling can be a problem when free flying, so can it be a problem when skyting. Therefore, a pilot should know what to do when a stall occurs. Unlike free flight, which has one stall recovery technique, skyting has three stall recovery techniques which can be used. Each of these methods is discussed below:

METHOD 1: CONVENTIONAL STALL RECOVERY

In free flight, the standard stall recovery technique is to PULL IN ON THE CONTROL BAR TO LOWER THE ANGLE OF ATTACK AND TO REGAIN FLYING SPEED. Since skyting, by definition, is free flight under a simulated gravitational field, then it follows that conventional stall recovery should work just as well as when free flying. And, of course, it does.

Unfortunately, it also results in a slack towline because the glider is then traveling faster than the tow vehicle. If the vehicle does not speed up, then the glider has lost all power and the pilot has no choice but to land. But even if the vehicle does speed up, it is probably wise for the pilot to abort the flight once the towline becomes slack. FLYING WITH A SLACK TOWLINE CAN BE QUITE DANGEROUS. There is a real possibility of the slack line tangling with the ground, the glider, or the pilot, and there is potential loss of control when the line suddenly becomes tighter later on. Therefore, whether the vehicle speeds up or not, a conventional stall recovery almost always results in an aborted flight.

METHOD 2: PARACHUTING

A second method of recovering from a skyting stall is to "parachute" the glider. Instead of pulling in on the control bar, PUSH OUT ON THE CONTROL BAR AND FORCE THE GLIDER INTO AN EVEN GREATER STALL SO ITS FORWARD SPEED IS SLOWER THAN EVER. Since some gliders "parachute" better than others, this method may prove to be more effective for some gliders than for others. However, true "parachuting" ability is not required because true parachuting in never performed. There is always some forward motion of the glider unless the vehicle actually stops in a no wind situation.

When parachuting, the forward motion of the glider is less than that of the vehicle, so the towline tightens and tension increases. Eventually the tension becomes adequate for continued flight. Depending upon the circumstances, the tension may thrust the glider forward above its stall speed, or it may simply drag the glider through the air in a mushy, stalled flight.

If the vehicle never speeds up, then the mushy flight will eventually have to be terminated by the pilot by pulling in on the control bar. This will cause the drag to decrease and the stretched towline tension will accelerate the glider to normal flying speed. In other words, eventually the second case becomes the same as the first case and the glider begins moving faster than the vehicle. Then either the rope grows slack or else the glider slows back down and another stall results.

But if the vehicle speeds up during the parachuting stall recovery the pilot can pull in on the control bar and resume his normal skyting flight. This is the primary advantage of the parachuting recovery technique - it permits a continuation of the flight after recovering from the stall without the danger of flying with a slack towline.

The main danger in using this technique to recover from a stall is that there is always the possibility that the vehicle may slow down even more. If this happens, then the pilot is going to find himself in a severe freeflight stall situation. What happens then depends upon pilot ability, glider performance, and flight altitude. Most pilots, I am sure, would rather avoid this situation - especially at low altitudes. The method, therefore, is recommended only for experienced pilots flying proven equipment at altitudes adequate for conventional recovery from severe stalls.

METHOD 3: TRAVERSING

A third method of recovering from a stall is to TURN THE GLIDER AND FLY TRANSVERSE TO THE MOTION OF THE VEHICLE. (Here, as elsewhere in this article, we are assuming a person is meeting the SKYTING CRITERIA. To attempt this method using a conventional towing system is to guarantee a severe lockout.) By making the glider fly at some angle to the vehicle's motion, its air speed is increased. the amount of increase in the air speed depends upon the size of the angle.

Figure 1 illustrates this phenomenon. If a vehicle is moving at 18 mph (well below the glider's stall speed) and the glider traverses at a 45 degree angle, then the glider will have an air speed of more than 25 mph (well above stall speed). Similarly, if he should turn crossways at a 60 degree angle, he would be moving at 36 mph! Under these conditions, it is obvious that stalling would be no problem.

Of course, you cannot continue flying sideways forever on a rope of finite length. Eventually you are going to have to stop moving to the side. If the vehicle has sped up during your traverse flight, you can simply let yourself drift back behind the vehicle. Otherwise, you will have to turn around and traverse back to the other side. In principle, this traversing from side to side may be continued indefinitely.

By the way, this technique should only be performed on a long, elastic towline and the turns should be made before getting too far to the side of the vehicle, then it will have to fly back "down wind" before returning to its starting point. If the speed of the vehicle is only marginal, then the resulting transverse angle will become so great that the upper bridle line will touch the flying wires (which is a NO-NO). Without a long, elastic towline, the rope is almost certain to become slack during the turn-around (which is also dangerous). And finally, there is the danger of a "whiplash" effect as the glider speeds down wind and swings back into the wind. (See Figure 2.)

The obvious advantage of this traversing technique for stall recovery is that when it is performed correctly, stall recovery is not only accomplished but the towline remains tight and normal flight speed is maintained even though the vehicle may continue moving below the glider's stall speed. The major disadvantage is the pilot needs both skill and experience in order to execute the technique properly.

WHICH TECHNIQUE SHOULD BE USED?

So now that we have three methods of recovering from a skyting stall, which method is considered the best and under what circumstances should each be used? Well, each method has its advantages and disadvantages, so there is no single method which is always the "best". Sometimes more than one method is equally appropriate, while at other times one or the other method is clearly superior. In the space below we shall discuss some typical skyting stall situations and consider the recommended method of stall recovery.

PURE SKYTING

Since pure skyting (See The Skyting Criteria, WHOLE AIR, July/August, 1982, is defined as free flight under an artificial gravity, then it follows that stall recovery when flying in a pure skyting situation should be the same as when flying free. In other words, as long as the towline tension is truly (1) constant in direction, (2) constant in magnitude, (3) distributed properly and (4) attached properly, then nothing but the conventional stall recovery technique should be used. Attempting the other two methods will have the same effect on tow as on free flight: Method 2 will simply increase the stall and Method 3 will simply turn or spin the glider.

INEXPERIENCED PILOTS

In my opinion, inexperienced pilots should use nothing but the conventional stall recovery technique. The beginning pilot must, from the very first flight, learn to develop a stall recovery REFLEX which is ALWAYS effective. Stalls are simply too dangerous to fool around with, especially if you do not know what you are doing. All too often there is not time - and I mean NO time - to think things out or try to analyze a situation before initiating the proper stall recovery technique. The proper response must be reflexive and immediate. Any delay could be terminally fatal. Only after the pilot has mastered the conventional stall recovery technique should he attempt to utilize the other two. By this time, his proficiency should be adequate to execute the other two without undue difficulty or danger.

Even experienced pilots should use conventional stall recovery techniques until they are familiar with the characteristics of the skyting system and feel comfortable skyting. If the line grows slack because of the stall recovery, then the flight should be aborted. It is better to abort the flight and fly again than to develop dangerous reflexes or to go against one's training.

TAKEOFF

One of the most common skyting stall situations occurs when the vehicle accelerates too slowly (or shifts gears) during takeoff. As long as a long, elastic towline is used, this presents no problem because the line stretch smooths out such fluctuations or lets the pilot remain on the ground until adequate vehicle speed is attained. But if a short or inelastic towline is used (even with a winch) slow acceleration can be a problem.

The parachuting technique (Method 2) of stall recovery has been used effectively in such situations (See Some Thoughts on Towing, in SKYTING NO.4), but I do not recommend it because there is always the danger that gear shift trouble may develop (or something else could happen) to force the vehicle to lose power instead of continuing to accelerate as it should. If this happens, then the pilot is going to find himself in a severe stall close to the ground - a very, very dangerous situation indeed.

Similarly, I do not recommend traversing (Method 3) during the takeoff situation. You are simply too close to the ground. Traversing should only be accomplished at higher altitudes. If something happened to cause you to suddenly lose towline tension (weak link breaks, winch slips, safety release tripped (operator thought you were in a lock-out), or other equipment malfunction) then you would suddenly find yourself in a low altitude down-wind turn - another very, very dangerous situation.

Again, it appears that the best stall recovery technique is Method 1 - the conventional stall recovery. If after recovering, you slow the glider down as much as possible without stalling again (a maneuver not recommended for beginners), there is still the possibility that the vehicle can continue accelerating to the proper speed before the line grows so slack that an aborted flight is required.

You may even want to do a touch-and-go on the runway instead of releasing (as long as you have everything under control). The important thing to remember when doing a touch-and-go is to keep your balance and keep the glider flying under control at all times. At the first sign of trouble, you should release yourself from tow. Remember, by the time you are doing your touch-and-go the vehicle is moving faster than you are, and the towline tension is going to increase to the point of rapid acceleration very soon. You must be ready for it when it comes. Again, the more stretch you have in your towline, the more time you have available to make your decisions.

SLOW TOWING

Suppose the vehicle is simply moving too slowly to maintain your flight. What should you do then? The answer should be obvious - signal the driver to speed up! But while he is doing this, conventional flying will result in a slack towline. Slowing down, of course, causes a stall.

Assuming this happens at a reasonable altitude, now is the time to apply stall recovery methods 2 and/or 3. In this situation, I prefer Method 3. I simply turn the glider and make a traverse flight until the conditions are again proper for forward flight.

MARGINAL KITING

Suppose the winds aloft are above the stall speed of your glider. Then the vehicle can stop completely and you can fly (kite) as long as you want. But if the wind drops below stall speed, you will have to use one of the stall recovery techniques mentioned previously. Method 3 is strongly recommended. (Method 1 will terminate the flight, and Method 2 could also terminate the flight if the wind does not pick back up soon enough.)

By traversing back and forth, flight may be continued indefinately under such marginal kiting conditions. In fact, once you are airborne, it is theoretically possible to maintain kiting flight in winds as low as 1/2 your glider's stall speed. This means winds as low as 10 mph. Although I have never accomplished this feat, I have kited in winds below my glider's stall speed and am convinced that such "rope soaring" will someday become quite common.

KITING TO THE SIDE

While kiting, it is quite easy to forget and fly too far to the side. When you make your turn, the towline becomes slack (or at least the tension decreases significantly) while you are being blown down wind. (See Figure 2). Under this situation conventional stall recovery (Method 1) would only increase the slack, and if you turn any further (Method 3) the towline will rub against the flying wires (which is a NO-NO), so if you are to remain airborne, you will need to employ Method 2. By pushing out on the control bar, you slow the glider below stall speed. The wind can then blow you back and the towline tension can be regained for continued flight.

GUST INDUCED STALLS

If a wind gust induces a stall while skyting, the stall causing situation should be only temporary. Normal stall recovery reflexes should be employed (Method 1) until the towline begins to grow slack. At that time a person could employ Method 3 by turning to a traverse path. However, the wisest course of action may be to go ahead and land, and stop flying in such turbulent conditions. (See How to Break An Arm, SKYTING NO.1.)

STALLED TURNS

If one of the wings of the glider stalls before the other, then a stalled turn (the beginning of a spin) will result. Again conventional stall recovery (Method 1) should be employed until the glider is flying. While the recovery is being made, the chances are that the glider will have turned crossways to the original flight direction. The pilot, instead of trying to quickly regain his original heading, should simply continue in the traverse flight direction until full and confident control is established and then bring himself back on course.

CONCLUSION

The above situations are examples of where stalls could occur, but there are no situations in skyting where stalls should occur. Just as in free flight, so in skyting, stalls should be avoided. And they can be avoided.if the pilot always flies sensibly in reasonable conditions and keeps his flight speed above the stall speed.
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Figure 1. Traverse Flying.
Vehicle
Glider

45 degrees
sideways speed 18 mph
forward speed 18 mph
air speed 25.5 mph

60 degrees
sideways speed 32.4 mph
forward speed 18 mph
air speed 36 mph
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Figure 2. Traverse Soaring

turn
down wind
cross wind
up wind
turn
down wind
cross wind
up wind
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DEAR DONNELL
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1982/09-02

BEGINNING TO TOW IN GERMANY

Dear Donnell,

Some time ago I read your article about towing in the Hang Gliding Magazine. I was very interested and waited for the next part. Since it never appeared, the whole thing was forgotten until I came accross Henry M. Wise's letter in Glider Rider. Now I just have your system, because we are starting to tow here in Germany in a few weeks.

Last year we towed, trying out all different methods as a trial run to prove to our government that it is safe if done correctly. (Before that towing was prohibited because they considered it too dangerous.) We did have our problems with lockouts and there were two fatal towing accidents in that period of time. The accidents happened because unexperienced people were using the wrong equipment.

Enclosed please find three dollars for information and postage.

Thanking you in advance, best regards and safe flying.

Peter Roth
Neu-Isenburg, Germany
*
1982/09-03

GUATEMALA INTEREST

Dear Donnell,

I read the March/April and then the May/June issues of Whole Air and am very interested in the Skyting concept. What I would really be interested in would be the marketing of the whole system, pulleys, rope and all. Please let me know if you plan on selling the Skyting system (all accessories included) or if you know who will.

In the meantime, please send me your Skyting No. 1 publications for which I enclose $2.00.

Fernando Linares
Guatemala City, Guatemala
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1982/09-04

KEEPING CURRENT

Dear Donnell,

I picked up a copy of your SKITING at Kitty Hawk Kites in Nags Head, N.C.! I am very interested in keeping current on the developments of skyting. I saw a price of $10.00 for a subscription. Please include the first issue in my subscription. Enclosed is a check for $10.00.

Don Southwick
Beach Haven Terrace, N.C.
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1982/09-05

SAFETY REMINDERS

by Donnell Hewett

The purpose of this column is to review both serious accidents and potentially dangerous situations in order to identify, and remind ourselves of, those mistakes which pilots have a tendency to repeat.
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1982/09-06

ACCIDENT:
BEGINNER STALLS AND CRASHES

Recently in Houston, Texas, a beginning pilot with no skyting experience and only a little hill-flying experience was training under the supervision of an experienced skyter. The ground crew had towed advanced flyers before, but this was apparently their first attempt to tow a beginner. The flight plan, in accordance with skyting's gradual advancement provision, was to tow the pilot no higher than 3 ft. But the actual flight carried the pilot up to 50 ft, at which point the spotter tripped the safety release. The glider then stalled and crashed, breaking the control bar and fracturing the pilot's heel.

ANALYSIS:

As is usually the case of skyting accidents, more than one mistake was made and more than one "safety rule" was broken. The discussion below lists some of the rules broken and explains how they were broken.

RULE 1. NEVER TRY TWO NEW THINGS ON THE SAME FLIGHT. This is an old hang gliding rule, and is sort of a corollary of the "gradual advancement rule". In the above accident we see the ground crew learning to skyte a beginner while the beginner is learning to skyte. In my opinion, the skyting expert should have played the part of a beginner while the ground crew practiced the beginner towing technique. In the mean time, the beginner should have carefully watched the expert demonstrate the proper way to execute the beginner flight tasks. In this way, when the beginner's turn came to fly, the ground crew would have had the necessary experience and the beginner would have known exactly what to do.

RULE 2. REGARDLESS OF WHO IS REALLY AT FAULT, NATURE HOLDS THE PILOT RESPONSIBLE FOR A HANG GLIDING ACCIDENT. (Look who got hurt.) Skyting is designed to give the pilot more control over his flight than any other member of the flight crew. Even if the ground crew "goofs up", the pilot has the means to get himself out of danger if he only does the right thing. Of course no one can expect a beginner to react like an expert during an emergency situation, but in this accident, all the pilot had to do was keep the control bar pulled in. If he had done this, he never would have climbed to such an altitude (unless the driver really drove much too fast), nor would he have stalled when he was released (even if the driver had gone too fast). The beginner should have known this much from his ground training (or else he was not qualified to fly in the first place). If he knew what to do but failed to do it, then he had better learn not to panic whenever an emergency situation arrises. Next time he may not be so lucky.

RULE 3. BEGINNERS SHOULD SKYTE WITH THE BODY LINE PASSING THROUGH THE CONTROL BAR. When the body line is passed under the base tube, it pushes up on the control bar during takeoff and makes it more difficult to keep from climbing. Conversely, when it pushes down on the base tube at high angles and makes it difficult to peak out. Since beginners have no need to peak out, but rather to keep their altitude low, they need to tow with their body line over the base tube. (Experienced pilots do the opposite for the opposite reasons.)

It was not clear from the given information whether or not this rule was broken during the accident, but I suspect that it was not broken. Breaking the rule would help explain why the beginner climbed too fast, but it would not explain why the glider stalled when released. If the pilot had been trying to keep his nose down, he would have succeeded as soon as the towline tension was releaved.

RULE 4. THE DRIVER SHOULD WATCH THE PILOT DURING A SKYTING TAKEOFF. This is particularly important when towing beginners. The beginner usually has neither the skill or the knowledge to accept full responsibility of his flight. He is depending upon the ground crew (and especially the driver) to help him control the situation. Never forget that although the pilot flies the glider, it is the driver that controls his throttle. Therefore the driver is second only to the pilot in his ability to control the skyting situation.

During the critical maneuver of a skyting takeoff the driver simply cannot afford to rely upon information supplied by the spotter. By the time the information is transfered from the pilot's feet to the spotter's mouth to the driver's ears to the driver's foot to the vehicle's breaks, the beginner can be 25 feet off the ground. (And in another couple of seconds he can be 50 feet off the ground.) When towing beginners on their first flight, the driver must hit the breaks as soon as he sees the pilot's feet leave the ground. Even so, the beginner who pushes out too hard may find himself coasting several feet off the ground. This is particularly true if a long elastic towline is used. Therefore, a short (100 ft) non-elastic towline is recommended for beginners. Although this makes the takeoff run longer and more difficult, it also gives the driver more control over the situation. (A long, elastic towline is recommended for experienced skyters for exactly the opposite reasons.)

Regardless of the length of the towline, it takes a certain amount of driving practice in order for a driver to accurately regulate (or limit) the height of a beginning pilot. Obviously the most qualified driver available is the one who should be driving. This usually means that the instructor should be the one driving the vehicle instead of simply supervising the activities from the ground.

RULE 5. STOP THE VEHICLE INSTEAD OF TRIPPING THE SAFETY RELEASE. In the accident being discussed, the abrupt loss of towline tension was probably one of the main reasons the glider stalled. If the vehicle had slowed down without tripping the safety release, then the tension in the towline would have gradually decreased and the glider probably would not have stalled. But even if the beginner had kept pushing out and stalled the glider, the stall would have been less dramatic because of the presence of some tension in the towline. In fact, the ground crew can make a stalled glider gently descend toward the ground by driving the vehicle at the correct speed. This, of course, requires considerable driving skill, but it can be done.

RULE 6. NEVER DEVIATE FROM THE AGREED ON FLIGHT PLAN. It is always dangerous for either the pilot or the ground crew to deviate from an agreed upon flight plan. The result is always a surprise to the other crew members and they no longer know what to do in order to keep the rest of the flight safe. I personally make it a policy to terminate the flight as quickly as possible (but as gently as possible) whenever someone deviates from the flight plan and I no longer know what to expect.

RULE 7. DO YOUR HOMEWORK. It is important for both beginners and experts to understand the flight theory and safety practices already published in the literature. Apparently one or more of those involved with this accident either was not aquainted with, or else did not fully appreciate, the material already written about stall recovery and the skyting gradual advancement plan. I suggest that they go back and review this material.
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1982/09-07

INCIDENT:
TURNED CROSSWAYS AT 90 DEGREES

On the same day and at the same place as the previous accident, another pilot found himself involved in a dangerous incident. It began with a wind gust which turned the glider approximately 45 degrees crossways to the towline. The pilot started to correct the problem by turning back on course, but then he became concerned about the possibilities of a lockout and decided it would be wiser to release. While he was reaching to release, the glider continued to turn away from the vehicle until it was approximately 90 degrees crossways. At that time the spotter tripped the safety release, freeing the towline from the vehicle. The pilot then went on to land without apparent difficulty.

ANALYSIS:

According to skyting theory, there is no danger of a lockout as long as the bridle line does not touch the control bar or flying wires. At the original 45 degree deviation it is doubtful that this occurred, but at the final 90 degrees deviation it is almost certain that it did occur. Therefore, there was no danger of a lockout at 45 degrees, but there was considerable "potential" danger at the 90 degree situation. Exactly how much danger no one can say, for the skyting system has not been adequately tested at such extreme limits. In any case, the safety rules that applied to this incident are as follows:

RULE 1. STOP THE VEHICLE INSTEAD OF TRIPPING THE SAFETY RELEASE. The above incident is one of the very few instances where breaking this rule seems to have the proper course of action. Tripping the safety release probably prevented the incident from becoming a serious accident. But in general, it is better to stop the vehicle instead of tripping the safety release.

Obviously a lot of experience (and knowledge of what the pilot is likely to do) is needed in order for a spotter to react properly to an emergency situation. The importance of a good spotter to skyting safety should not be underestimated. This incident also illustrates why a single person cannot effectively act as both driver and spotter. No one can carefully drive the vehicle and carefully watch the pilot at the same time.

RULE 2. NEVER LET THE BRIDLE LINE TOUCH THE FLYING WIRES. In the above incident, the pilot made a major mistake in failing to follow through with his initial attempt to get his glider back under control. I can understand his fear of lockouts, but as long as the bridle line did not actually touch his flying wires there was no need for him to be concerned. If he had concentrated on controlling his glider instead of trying to release from tow, the whole incident never would have happened.

RULE 3. NEVER RELEASE WHEN THE BRIDLE LINE IS TOUCHING THE FLYING WIRES. There are times when the pilot cannot prevent his bridle line from contacting his flying wires or control bar. Whenever this happens, he should never try to release, but rather he should increase his efforts to turn the glider back where it belongs.

It is true that flying with the bridle line touching the flying wires is potentially dangerous, but attempting to release under this circumstance is even more dangerous - much more dangerous. If you try to release in this situation, there is a large probability that the keel latch will fall over the flying wire, slide down to the corner of the control bar, and become tangled. Unless the ground crew releaves the towline tension (by stopping the vehicle or tripping the safety release), then the pull on the corner of the control bar will cause the glider to do a type of "wing-over". This happened to me once, and I never want it to happen again. It is certainly as bad as, if not worse than, a lockout. At least in the case of a lockout you have a possibility of releasing yourself.

On the other hand, when the pilot continues to try to turn his glider back onto its intended course (even if the cross angle is as great as 90 degrees) the towline forces normally tend to help him accomplish his goal. The reasons for this are described below:

When the bridle line touches the flying wire, the force on the wire tries to roll the glider in the wrong direction and to yaw the glider in the right direction. These situations are illustrated below:
+
ADVERSE ROLL
Back View
+
FAVORABLE YAW
Top View
Fast Wing
Slow Wing
+
The adverse roll tries to turn the glider in the wrong direction just like the conventional "lockout". The favorable yaw tries to turn the glider in the right direction. It also speeds up one of the wings and slows down the other. The faster moving wing experiences more lift than the other and this causes the glider to roll in the correct direction, as illustrated below:
+
FAVORABLE ROLL
Back View
Fast Wing
Slow Wing
+
Whether this favorable roll tendancy is greater or less than the adverse roll tendancy apparently depends upon the particular circumstances.

In addition to the above mentioned roll and yaw tendancies, there is some sideways force on the pilot due to the body line. This is illustrated below:

PILOT WEIGHT SHIFT
Back View

As can be seen, this sideways force tends to pull the pilot over to the correct side to make the glider turn naturally in the proper direction.

The net effect of all these forces acting together has, in my experience, always helped turn the glider in the correct direction, even at cross angles as great as 90 degrees. Never-the-less, I do not recommend that you deliberately place yourself in a situation where you need to rely upon these forces to help get you out. You may just discover a particular case where they do not help. Neither the theory of these forces nor the experimental testing of such situations can be considered complete at this time.
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1982/10
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SKYTING NO. 6
October 1982
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1982/10-01

REFLECTIONS ON THREE YEARS OF SKYTING
or
The Real Truth About Skyting

by Richard "Red" Wylde

It all started out normal enough. We went to Padre Island and did some flying off a 15 foot sand dune, which was fun. Right away I started having trouble landing. I dragged my feet over 30 feet on my last flight and then bellied in! From then on it was all downhill!

We came back to Kingsville, which is flat as a table for 200 miles in any direction, and decided that the way to fly was to tow, but the towing systems available cost more than the glider we had. Also, we were supposed to tow using a boat on a lake. Well, we didn't have any money. So we tried people towing and quickly found that people towing worked fine for about 20 - 30 feet and then they ran out of power (breath!).

Keep in mind that I didn't know how to fly and Donnell only had two days of lessons in Calif. 2 or 3 years previously. Also we didn't have much information on towing except that you had to have experience in order to do it. This caused us some problems because the only way to fly around here was to tow - but we had no experience. Well, we didn't let that stop us. We pressed on anyway.

We found a large field behind a new school and across the street from a convenient cemetery! We decided to use my motorcycle (a 750cc Yamaha with fairing and saddlebags) to provide the power, partly because it didn't track up the school yard and it was cheap (no money, remember?).

So we started working on towing and learning to fly at the same time. I would stop by Donnell's and he would be all excited and show me some papers with diagrams, charts, figures, arrows, numbers and other strange stuff on them (he is a physics professor) and he would say, if we did this, such and such would happen. I would look at the papers and say ok ?! We had a rule when we went flying that if someone had some new idea he had to try it first, so Donnell got a lot of first flights!

Also during this time Henry Wise, the guy that got us started by letting us use his glider, would come down from Corpus Christi to help us. He was deathly afraid of towing so he kept saying, "Don't go so fast, don't try so many new things, be careful, and GET THE NOSE DOWN!!"

So we progressed along using my motorcycle and a 100 foot rope. We would have one person ride backwards holding a stick with the rope looped around it, watching the glider and giving signals to the driver (it's hard to drive a 650 lb motorcycle and look over your shoulder at the same time without falling over!). For the longest time Donnell thought that the only way to ride a motorcycle was to sit backwards on it! We would have a pilot flying and we usually had someone running a movie camera. We didn't get very high or fly very long, but we were FLYING. We bent the glider a lot, but we learned how to straighten bent downtubes. The best tubing straightener we found was a large, firmly fastened down ... tree! They just don't move when you try to straighten a tube.

Finally we got the towing system to almost what it is now and I had quit bruising my knees (bad landings). We found a school yard wasn't big enough when on one of my flights I released late and was higher than usual (about 60-70 feet). As I came in, I had to turn to miss the wind sock pole, flew over Donnell's two girls, missed some trees, flew under a phone line, and landed about 10 feet from the school building (made of very hard brick). We decided we needed a bigger area!

We were able to convince the local airport manager to let us use the almost abandoned grass strip. We then found that with a longer rope and more altitude, the glider could induce some strange handling qualities to the motorcycle. Also it was a long way to carry the glider back to the starting point. So we switched to using my Toyota pickup. We could carry more observers, the glider didn't pull the truck around, and we could carry the glider back.

Shortly after this we made some wheels for the glider and I found out that I could save a blown take-off when I started to fall by pushing out real hard, hitting the ground on the wheels and, if the truck kept going, I could still fly!

Now that we were at the airport we could really learn to fly. We worked on turns, cross wind take-offs, stalls, speed control, and spot landings. We got good on our landings. Donnell bellyflopped on top of one of those big round hay bales and slid off the other side! I landed in the ditch along the edge of the runway. It was full of very wet and cold water!

We found out we shouldn't believe everything people say when they want to fly. We let some guy fly who said he knew all about towing. We towed him up to 25 feet, he stalled, kept the nose up, and crashed. He cut his chin and tore up the glider.

We learned about flying in gusty, turbulent winds. We both made a couple of flights where, after we released, we were flying ok but our track across the ground was backwards! It's hard to land going backwards - you can't see where you are going!!

I also found out that the airport has a kite eating tree! I was trying to kite, but the wind wasn't quite strong enough for me. (Donnell had just completed 4 minutes of kiting, and I wanted to do it also. Donnell weighs 50 lbs. less than I do, and we use the same glider.) So I was coming down slowly and I was watching this tree below and off to my side - and because of that I crashed going sideways, downwind, and ground looped the glider. It cost $60 to fix it up. I wasn't hurt, if you don't count pride.

We still tried some rather novel (strange) ideas. We had been using a 100 ft piece of bungiee cord tripled up as a shock absorber, but it was getting stretched out and we were needing something new. Virgil Newman, who was a Navy parachute rigger and who was involved with us from the start, got a 25 lb practice bomb that the Navy A-4 jets use, and we tied it in the middle of the tow rope to provide some tension on the line. It worked out ok but looked funny. We only used it a couple of times. We figured those were the first bombing runs made with hang gliders! After we went to using parachute shroud line we found it had enough stretch that we didn't need bungiee cords or bombs. Progress marches on!

Now we really could progress. We were using 600 ft of rope, getting up to 400 to 500 ft, and landing on the runway. Donnell usually landed back at take-off. I could only get half way back. He is 50 lb lighter, remember?

One day we decided to have some fun and tow two gliders at the same time. We had one tow rope shorter than the other, we had two safety observers in the truck, and we agreed that if a weak link broke, the other pilot would release, and we would start over. We had a big briefing with the driver, observers, pilots, ground crew, and camera man. Then we tried it. The first time we went a little too fast and Donnell broke his weak link. So we tried again, and the second flight went well except the cameraman ran out of film half way through, so we had to do it again. The third flight was the best and we got it all on film. It was fun, but we haven't done it again. Maybe someday we will do it again.

We also tried something else that didn't work out as well. Donnell got the idea that he should be able to tow to one end and then turn around and tow back without releasing. So we briefed everyone about procedures and tried it. The first part went ok. While the truck was turning around, Donnell was making a slow 180 trying not to lose too much altitude. The truck was truned around heading downwind, we were doing 50 mph, and the tow rope was just starting to get tight. We finally started giving him some power as he was about 5 feet off the ground. We went off the mowed part of the runway at 55 mph with grass and weeds flying over the truck and Donnell gaining altitude. We finally stopped when he released, turned into the wind, and landed. It wasn't too much fun, we haven't tried it again, and I doubt if we ever will! We did learn one thing though, always tow into the wind. Don't try downwind towing - it's hard on the truck!

Well, it's 3 years later, I have converted our first glider into a LEAF Talon 215. Donnell has ordered a new Gemini, and we have both foot launched off Packsaddle Mt. Now when I tow up to 400 - 500 feet, I can look around. I can see Kingsville, which is 10 miles away. The airport looks small. I'm able to to look down on passing cropdusters (they're afraid of heights), and it's fun. Can enjoy the flight. So I guess that the towing system works. I've never had a lock-out, although I'm sure I've had plenty of chances. I haven't seriously hurt myself, if you don't count matching bruised knees! I've mastered the basics of flight. I can do crosswind takeoffs, stalls and recoveries, 180's, 360's, land safely, and handle turbulence. We have had a good time and I'm going to miss my friends and this flat land flying. But I have a towing system, my wife knows how to drive the tow truck, and as soon as I can get a CB radio on my glider and find a new place to tow, I'll be back in the air.
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1982/10-02

A FAIRWELL TO RED

by Donnell Hewett

Richard "Red" Wylde has assisted me in the development of the skyting towing system more than any other person. He has been with me from the beginning, supplying financial assistance, ideas, and encouragement. He was with Virgil Newman and I when we attended the first South Texas Hang Gliding meetings organized by Henry Wise over three years ago. He put up half of the money needed to buy the Standard Rogallo with which we learned to fly. He supplied the motorcycle used in our early towing experiments. He provided many of the components used in the development of skyting. He did much, if not most, of the glider and equipment repair. He helped test the system during each phase of development, debated the worthiness of new ideas, and supplied the constructive criticism so necessary for improvement. In other words, skyting never would have been developed without his assistance and encouragement.

But now Red, like Virgil and Henry before him, is moving away from the South Texas area. He and his wife, Cece, are moving to Chicago where Red is to receive some Navy training before departing to parts unknown. He does not know when he will be flying again (although he hopes to do so by next spring).

Fortunately, the development of skyting has now expanded beyond the limits of Kingsville. There are many of you throughout the United States and other parts of the world who are currently adapting what we have learned to your own flying needs. As you communicate with others what you have learned, then safe and enjoyable towing will finally begin to reach its full potential.

As for me, I plan to continue trying to encourage such mutual communication and to train others here in Kingsville to take Red's place. But in all honesty, I doubt that anyone will ever be able to quite take the place of Red.
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1982/10-03

Low Tension Winches

by
TIDEWATER HANG GLIDING ASSOCIATION
456 Garrison Place
Virginia Beach, VA 23452

Much progress has been make in the design, and successful utilization of power winches used to tow hang gliders. This has opened up flying sites, and possibilities for pilots everywhere. However, since equipment is relatively new, there seems to be a lack of information about this equipment. This discussion is limited to stationary, powered, tension-limited, hang glider tow winches. These winches allow pilots to safely tow up to 1,000 feet or more, from flat ground. Pilots are no longer dependent on mountain site availability.

The main safety feature of the tension-limiting winch is to prevent structural failure of the glider, due to overspeed, excessive angle of attack or turbulence. This is a major safety advantabe over previous towing methods.

There are several other benefits of "tension limited" towing; the first advantage being pilot control effectiveness. Under large tow-line tensions, the wing loading of the glider is increased, which causes slower response times for equal pilot control inputs. This shows up as a lag in roll and yaw rates, while under high tensions. This is somewhat disconcerting, even to experienced pilots, and is substantially reduced with low-tension towing, since it remains below 120 pounds line pull. We have found this value to be advantageous for a good climb rate, 600+ fpm, and a mellow take-off; i.e., two to three steps, not "pop-start"). This tension is enough to accelerate a 300 pound pilot/glider system from 0 to 24 mph flying speed in about three seconds. The lower tensions make take-offs smooth, predictable, and controllable. Glider control, with low line tensions, is easier and safer.

There are also performance increases associated with low tension towing. Maximum climb angle is realized when a glider is towed at minimum sink speed angle of attack. Flying in this mode provides maximum altitude per available line length. It also results in moderate climb rates, and angle of attack with respect to horizon. This is a much safer, and more controllable way to tow up. The low tow line tensions also take maximum advantage of any available headwind. The low-tension winch starts slowing, or even unreeling line much sooner than the higher tension winches.

Because the line tension is limited to below 120 pounds force, the horsepower requirements are cut considerably. As tension limiting winches developed, the horsepower requirements have steadily dropped. We have found that 8 B.H.P. is sufficient power for good operation of a low tension winch. This also reduces the cost of the towing equipment drastically. By matching power available with power required, there is little waste in size, weight, and complexity of the equipment. (See Fig. 1 for torque, horsepower, line speed, and tension relationships.)

Another consideration of stationary winches is the effect of the drum movement of inertia on line tension, with changing kite velocities. A large, heavy, rotating drum can store energy, just like a fly wheel. If the drum is accelerated or decelerated rapidly, substantial power can be stored, or given up. For instance, an 18 inch diameter drum, weighing 150 pounds, turning at 448 rpm (corresponding to 24 mph line speed), can cause a line tension spike of 234 pounds, if decelerated to stop in one second. This is an undesirable effect, which could cause structural failure in gusty conditions. Any state-of-the-art winch design incorporates a drum with low moment of inertia; i.e., light weight, and small diameter (say 10 inches) to limit line tension spikes due to glider decelerations. A 10 inch drum, weighing 50 pounds, decelerated from 24 mph peripheral speed to stop in one second produces a line tension spike of only 74 pounds. The difference in safety is obvious.

Because of advances in winch designs, the cost of a tow winch is now less than the cost of many gliders. The size has been reduced, so that now it slides into the back of a Ford Pinto, and the weight reduced, so that two pilots can lift, and maneuver it into position.

More and more pilots are towing up in the flatlands, to soar tree lines, or fly cross-country; which is opening up new opportunities for pilots, schools, and dealers across the country.
+
Fig. 1. Horsepower Requirements for Various Towline Tensions and Speeds.
Power Requirements (hp)
Towline Tension (lbs.)
Towline Speed (mph)
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1982/10-04

ADJUSTING THE SKYTING BRIDLE

by Donnell Hewett

There have been several recorded instances where the keel lacth (top release) of a skyting bridle has released itself prematurely. (See the Dear Donnell column of this issue.) Needless to say, this is extremely upsetting to pilots who are not familiar with the skyting system, and very annoying to those who are. If you have never had it happen to you, you can imagine what takes place.

There you are, some time after take-off, climbing along with everything apparently well under control when - WHAM! The glider suddenly jumps back, and you feel a sharp increase in the pull on your body ring. You're certain that something has just broken, but you're not sure exactly what. In a panic, you look around to find out what happened, while you are trying to decide whether to release from tow or throw your parachute - or both! You find that the glider still seems to be intact and under control, although the control bar has shifted backwards from its normal flying position. Then you finally realize that the keel line of the bridle is no longer attached. For some reason, the keel latch has prematurely released itself.

Now if you have studied the theory of towing presented in SKYTING NO. 1, you realize that there is no real danger and that you can once again relax. If you wish, you can continue your flight on up to altitude. By flying purely on the body ring, the glider-pilot system will not be trimmed as well as when using the skyting bridle, so flying will not be as comfortable, but there is still no danger either of lockouts or other loss of control. Of course, as soon as you land, you need to figure out exactly why the premature release occurred so you can prevent it from happening again. You should also inspect your equipment for possible damage. There have been cases where the friction during this high tension event burned the auto-release line into its knot. (See WINCH TOWING EXPERIMENTS in the Dear Donnell colums of this issue.)

THEORY OF CORRECT OPERATION

As mentioned in SKYTING NO. 1, the skyting bridle is designed to distribute the towline forces between pilot and glider proportional to the masses of each. The auto-release line is designed to automatically release the keel latch when the body latch is released. As the body latch falls away from the pilot, the towline tension pulls the tow slip rings together and causes the auto-release line to tighten. The auto-release line then transfers the towline tension to the sleeve of the keel latch causing it to release.

Notice, however, that the keel latch has no way of knowing what causes the auto-release line to become tight. The only time the line is supposed to become tight is when the body latch is released, but if something else causes the line to tighten prematurely, the keel latch is going to release. Therefore, the main reason for a premature keel release is that the auto-release line somehow becomes tight before the body latch is released.

TANGLED TOWLINE

One reason the auto-release line may become tight and cause a premature release is that it somehow gets tangled in the bridle. The way to prevent this from happening is to make sure that all of the bridle lines are untangled (and untwisted) prior to take off. This of course, should be part of the pilot's regular preflight procedure (check list). The pilot should also watch to see that the auto-release line does not become tangled during flight. For example, he should be careful to see that the loose auto-release line is not blown against his head and become tangled with his helmet. In other words, the pilot should not become careless either before or during his flight.

SHORT AUTO-RELEASE LINE

But a tangled line is not the reason the pilots in the Dear Donnell column had a premature release. Their problem was that their auto-release line was too short for the particular geometry of their pilot-glider system. As the pilot climbed to higher altitude and the tow angle increased, then the bottom slip ring moved downward and rearward taking up slack in the auto-release line. Since the auto-release line was too short, then at a particular tow angle (or at a particular altitude on a given towline) the line became tight and pulled on the sleeve of the keel latch causing it to prematurely release. The solution, of course, is to lengthen the auto-release line.

LONG AUTO-RELEASE

However, care must be taken to make sure that the auto-release line is not too long or it will not work when it is supposed to. In this case, the pilot will have to reach up and manually trip the keel release in order to release the glider from tow. It is simple to check the operation of the auto-release line after adjustments have been made. Simply attach the keel latch to the keel ring and pull on the towline with the body latch unattached. If the auto-release line becomes tight before the two slip rings come together, the keel latch will release automatically.

FINE TUNED RELEASE

I, personally, prefer to have my bridle line "fine tuned" to my flying system. Specifically, one of my greatest worries is that someone is going to get his keel line tangled with his flying wires or control bar, but it could happen if the pilot gets turned crossways and then tries to release.

In order to prevent this from happening, I have tried to make the auto-release line just the right length to automatically release just before the critical condition occurs. In other words, I deliberately designed the system to release prematurely when the tow angle becomes great enough to cause the towline to contact the control bar.

Unfortunately, I failed to realize the difference in the geometry of various pilot-glider combinations. When a bridle which is fine tuned to my pilot-glider combination is used on a system with a larger control bar, or one with a keel ring in a different position, then the distance from keel ring to bady ring is changed, and the geometry for the proper release angle is changed. As a result, the same bridle which releases my keel at an 80 degree tow angle releases another keel at a 20 degree tow angle.

Since it is impossible for me to know the precise geometry of other flying systems, it is impossible for me to fine tune each bridle to meet the needs of every pilot.

Therefore, I am now making the auto-release line longer than they were previously, so that other pilots will not encounter the same premature release problem some of you have experienced. Future pilots will have to be more careful about letting the bridle line contact their control bars, or else they will have to fine tune their own bridle system to release just before contact takes place.

LENGTHENING THE BRIDLE LINES

Although I have never heard of it happening, there is a possibility of a particular pilot-glider geometry preventing the auto-release line from working in any configuration. If the pilot hangs so low that the slip rings are already touching, then either the auto-release line will not work or else it will release prematurely.

In this case, the length of the bridle lines must be changed. Specifically, the length of the body line must be shortened, or else the length of the keel line must be lengthened. Fortunately, these lengths are not critical to the operation of the bridle system. They must simply be long enough to clear the control bar at all towing angles, and the relative lengths must be adjusted so that the two slip rings do not come together at any time while under tow. Once these conditions are met, then the auto-release line can be adjusted to tighten up just before the two slip rings come together.

OTHER REASONS FOR PREMATURE RELEASES

There are two other possible reasons or a premature release. If the keel latch is not properly locked when attached to the keel, there is a possibility that it will prematurely release. However, this seldom happens because the latch is unlikely to hold at all unless it is properly locked in the first place.

The other possible reason for a premature release is that the spring inside the latch has become so weak that the unit has a "hair trigger". In this case, the weight of the sleeve may be adequate to cause a premature release, particularly when the glider is hit by a gust of wind. Again, this is unlikely, but if it does happen, the situation should be obvious when the latch is attached to the keel - it will be next to impossible to make it stay latches.

APOLOGY

I would like to take this opportunity to apologize to you who were inconvenienced or disturbed by the premature release of the bridle I sent you. In the process of trying to fine tune your system in accordance with my own, I wound up putting your system way out of tune. I am sorry. I would also like to express my thanks to those of you who called this problem to my attention. Without your feedback, I would still be sending out bridles with the same characteristics. Let's keep the feedback coming!
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1982/10-05

900 FEET IN NORTH CAROLINA

I received a telephone call from Peter Adams of Greensboro, NC. He said his team began towing behind a tractor but found it to be too slow in low wind conditions. They then tried a pickup truck but found it too rough for the crew when driving across the fields. They are now using an unfinished section of a four lane highway for their runway. Their tension gauge consists of a spring scale which reads to 200 pounds. So far they have towed up to 900 ft on a 940 ft parachute shroud line. Plans to use a 2000 ft line next and start flying cross country.

Ed.
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DEAR DONNELL
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1982/10-06

WINCH TOWING EXPERIENCES

Dear Donnell,

I received the bridle on August 13 and flew it that weekend. On Saturday winds were up to 10 mph. My first flight was a little shaky due to over correcting - I only towed up to 200 ft. The next flight corrections were much better. I was amazed at the roll response but was surprised at the adverse yaw. We then pulled out about 2000 ft of rope. Our winch does not have the speed a moving vehicle has, so our climb was much slower than your towing technique. You say that on 600 ft of line you get about 500+ ft, but every time we tried to top out the upper release would release. Have you extended your line for the upper release? I don't see with that (release) angle how you got that much altitude.

Something else concerns me - when anyone releases while still under tow for one reason or another the rope is being burned at the D-ring (slip ring). By Saturday afternoon our auto-release line was burned into. You might look at putting in some type of spacer to eliminate rope to rope contact.

I really enjoyed flying with your bridle. At no time did I feel out of control until we towed in no winds, flying a Flight Design 175 Demon. The bridle forces a high angle of attack and our winch would not maintain enough speed for us to have control. That is our problem, we hope it can be worked out.

I hope the comments made will be looked at. If you don't understand what I have said, please call me. Tell everyone that worked on this - thanks - you are on the right tow line.

Tom Pendergraft
Fayetteville, N.C.
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1982/10-07

FIRST SKYTING EXPERIENCES

Dear Donnell,

I'm finally writing the letter I promised. As you have stated previously in your newsletter, we have skyted in Missouri.

Our first attempt was using a 300 ft rope, 8-10 mile headwind, and a 1/4 mile dirt road. I was piloting my comet 165. We had read all the newsletters and after discussing signals, etc., were ready to proceed. The truck took off and I held back till the tension gauge read about 60 pounds. I took one step and was off. As I climbed to about 50 feet I felt a radical increase in air speed and climb rate. I decided it was time to test the releases. They worked so fast I hardly remember touching them.

I made another flight and this time the top release came off without help. The body latch was still attached and at about 100 feet, and air speed of about 25-30, there were no control problems. Since this premature release startled me, I quickly unhooked the body latch.

Dan Marcus was next up with his Firefly. His first flight was a repeat of my last. At about 100 ft the top release came loose. At first we thought it was the hair-trigger nature of the release, so we put a very thin strip of tape on it. This turned out to be a bad mistake. When Dan released the body latch, the top release did not. When we got to the end of our road, Dan glided down still attached.

By now we were kinda gun-shy at this new system but still game to keep trying. After all, our launches had been smooth and easy, control was no problem, and never a hint of lockout though shifting, gusty winds had taken us 45 degrees off course.

Dan and I made a couple more flights. None over 150 feet. Since neither of us had towed before, we were being understandably cautious. I broke the weak link at about 20 feet but recovery was no problem.

The last flight of the day was made by Mike Cope in his 209 Raven. He made a perfect take-off, climbed to 100 ft. The release worked perfectly. He landed. We packed up and went home.

During the course of the day we had learned quite a lot. We needed a much longer runway for one. Two, and probably more important, we needed more experience with the system, pilot as well as crew. We needed to find out why our top release sometimes went prematurely. We possibly need a more reliable release. (I'm making some 3-ring releases now.) In order to get up and into a thermal we needed to use a longer rope (naturally).

On the subject of experience, it is very unsettling at first to have 80-150 pounds tension tugging at a belt around your waist during flight. Of course this is not felt if you sew the body ring to your harness. We havn't done this yet. Also pitch and roll response under tow is disturbingly quick, as if you had just doubled your weight. (Effectively, you have.)

We did not use a weak link with 100 ft separation from the glider. The weak link was tied directly to the bridle. There was little momentum in the steel rings when the link broke. We felt the possibility of dragging 100 ft of rope through rough terrain might pose a greater hazard to the pilot.

On last note: the following weekend four of our local pilots tried out the bridle with a 900 ft rope. I'll let you know more about thier experience in my next letter.

Dennis Owen
Rock Hill, MO
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1982/11
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SKYTING NO. 7
November 1982
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1982/11-01

FOUR FLIGHTS ON A NEW GEMINI

by Donnell Hewett

Some of you have wondered why I have not bought a more modern glider than the old standard Rogallo which was used to develop the skyting system. Well, I just did. I bought a brand spanking new UP Gemini 164. There are three major reasons why I chose the Gemini: (1) Everything I read, heard, and saw about it indicated that it was an excellent, all-round glider for someone with my current skill level, and that it should be able to meet my needs for several years to come. (2) Its airframe was the same as that of the Comet - and I knew from previous experience (of other pilots) that the Comet towed well on the skyting system. It seemed reasonable to assume the Gemini would tow as well. (3) There was an UP dealer within 200 miles of here (closer than any other dealer) who was friendly and willing to help me get started.

My glider arrived at the dealer's shop approximately one month after I ordered it. And on Saturday, October 16, 1982, my family and I drove to Austin to pick it up. I received some instructions on its use and drove back to Kingsville on the same day.

It was the next Tuesday before I actually flew the glider. After work and before sundown, my crew and I drove out to the County Airport where we normally fly and set up the glider and the towing equipment. We took our time - carefully preflighting the equipment and familiarizing ourselves with the glider's characteristics.

The winds at our flying site were quite typical: strong, crossways, and gusty. Actually, they were not all that bad on this particular day. They were about 60 degrees crossways to the runway and blowing at 10 to 15 mph. The turbulence was milder than usual. Still, these conditions were pushing the upper limit of safe flying, especially with an unfamiliar glider. (You will recall the flying conditions under which I broke my arm. See SKYTING NO. 1.) There was no doubt in my mind that I could handle these conditions if I were flying my old standard, but I was not sure I wanted to risk crashing my new glider by flying it in such conditions. After all, I was familiar with Murphy's Law, having busted a hole in my new sail boat a few years ago before I even got it in the water. No way was I going to bust up my new glider on the very first flight!

But I am a firm believer that you can never get too much ground handling experience in any glider, and this seemed like a perfect opportunity to become familiar with the Gemini's ground handling characteristics.

GROUND HANDLING

I began testing the glider's handling characteristics in the wind without being hooked in; then I did some testing while being hooked in; and finally I attached the glider and myself to the bridle of the towing system. During these experiments we were using only 100 ft of towline and, therefore, were able to align the whole system directly with the wind. (We would worry about the cross-wind problem later on - if and when we decided to use the longer towline to tow the glider.)

Ho boy! Did the Gemini behave differently than the old standard. It's hard to describe the difference in retrospect, but for one thing, I had to really use the old muscles to get it to do what I wanted it to. It was hard to keep the nose down, hard to keep the control bar positioned correctly on my shoulders, and hard to keep the nose pointed into the wind. The Gemini was much more interested in flying than pointing its nose into the wind while on the ground. The large control bar was different, the control response lag was different, the tendancy to yaw was different, and the roll response was different. In one word, ground handling this glider was simply different to what I was used to.

As a result, I spent quite a bit of time ground handling this glider - approximately one hour. Of course, all of this time was not spent in actual combat - for that is almost how it felt - because the work was so exhausting I frequently had to stop to rest. Now when I say "exhausting", I do not mean to imply that it took a great deal of energy in the sense of running until you are out of breath. The fatigue was like that which occurs when you are tense and straining your muscles against one another. In other words, I was not able to relax! I was fighting not only the wind and the glider, but also myself!

Eventually, of course, I gained a better feel about getting the glider to do what I wanted it to do, and I was able to relax a little more. But I never was able to relax as much as when flying my old standard. This, of course, was only to be expected.

For those of you who are not familiar with our "kiting" and "ground handling" technique, let me explain how we do it. Whenever the winds are too strong or gusty to fly safely, we set up our own "hang-glider-flight-simulator". Specifically, we hook everything up exactly the same as when we tow, except we use a shorter towline and never move the vehicle. A safety line is attached to the nose of the glider and used by an experienced person to prevent the glider from climbing any higher than the nose man wants. Two other persons, one under the leading edge of each wing, "walk" along the ground beside the glider as it drifts from side to side, trying not to touch the wing unless it threatens to strike the ground. When this happens, the wing walker lifts up on the wing, preventing it from hitting the ground, and swings it around in the right direction to reposition and level the wings as they should be. In this manner the pilot is able to gain considerable flying experience while safely remaining only a matter of inches above the ground.

I didn't use a nose man when I ground handled my new Gemini because I was confident I could handle the pitch of the glider. But I did use the wing walkers to prevent me from damaging the wings on the ground.

Since the winds were only about 10 to 15 mph, I spent most of my time "tiptoeing" from side to side, but every now and then the wind would become strong enough to actually lift me off the ground. (By the way, I was surprised to learn that the Gemini would fly in such light winds - my other glider certainly would not have.)

During these few seconds of flight I was able to gain a feeling of the true flying characteristics of the Gemini. And through these experiences I became confident that I could safely fly the Gemini under these conditions. So we set everything up for my first flight with the new glider.

FIRST FLIGHT

Under normal circumstances a crosswind take-off of 45 degrees to 60 degrees would be no problem, but this situation was not exactly "normal". In fact, with this new glider, both the take-off and the landing could prove to be a problem. This made me a little apprehensive about trying to follow skyting's gradual advancement provision. A lot of short flights under these circumstances might prove dangerous. It appeared to be safer in this situation to plan on making the first flight a long one so that as much flight experience as possible could be gained with a minimum number of take-offs and landings.

I decided to take off and then climb slowly as long as everything was under control. If anything went wrong, I would release and land the glider into the wind and on the runway - if possible. Everything was ready and I was in position to go. From my point of view the flight went something like this:

All right, Donnell, make your final check to see that everything is correct. The vehicle is ready (having already given its signal). The bridle line is untangled. You're hooked in. The glider's nose is into the wind. The towline is tight. The right wing (the one facing the tow vehicle) is high as it should be for cross-wind take-offs. Are you mentally and emotionally ready? Yes! Then give the GO signal.

You're committed now, so you better keep the glider positioned properly while the vehicle gains speed. The towline's getting tighter. Now take a few slow steps, holding back on the towline while the rope stretches. The glider's flying. Faster now, and we're airborne!

Good take-off. Everything's under control. We're climbing gradually at about the planned rate. The glider is crabbing sideways over the runway as it should in the cross-wind situation.

WHAT'S THE MATTER? The glider wants to turn left! You better shift your weight to the right. Hey, it's still turning left! Shift your weight some more! Watch out, the keel line is touching the right flying wire! It's too late to release now! You're going to have to ride this one out, Donnell! More weight shift! Well, we didn't plan it, but it looks like we are going to find out real quick if the bridle line helps bring the glider back around where it belongs or tries to bank it over the wrong way into a lockout. Here's hoping your theory's right!

WOW! I'll say it brings it back around! It's already reversed its direction and started turning back to the right! But it's turning too fast! Quick, shift your weight back to the left before it overshoots. It's still turning. You'd better correct some more! It's over shooting - turning too far. More correction! There, it's starting to slow its turn. Better stop correcting or we're going to repeat this whole thing.

YEP, there she goes, reversing her direction too fast and turning back to the left. Donnell you are over-correcting. You better slack off and let the glider do more of the flying before this oscillation gets completely out of hand! But it's turning too far! The bridle line is hitting the flying wire again! There's the reverse! Now we're going back to the right. We've got a long way to go before the line touches on the left, so we can afford to relax and let the glider find its neutral position.

AH, there we go. Things have pretty well stabilized now. UH OH! In this down wind turn, we've let the towline grow slack. This is certainly no time to try flying further down wind to tighten it up, or to slow down and chance stalling an unfamiliar glider. We'd better just go ahead and land. The car has stopped, that's good. We're still over the runway. Better turn the glider into the wind - this is no time to practice a cross-wind landing. There, everything looks good. But don't forget, this Gemini is supposed to be harder to flare than the old standard. Get yourself upright. Hands on the down tubes. Here comes the ground. Alright, start your flare. Not too much, you don't want to climb up and stall! Good - good - touchdown! Now don't lose control here on the ground. Get the nose down. Unhook. ALL RIGHT!" Say, that was a pretty good flight - at least you didn't break the glider.

SECOND FLIGHT

The previous flight lasted about 50 seconds and reached an altitude of about 100 ft. We had used up only about 1/5 of the runway, so we decided to start the second flight from where the first flight ended. Within a few minutes we had everything ready to go. The second flight went something like this:

All right, Donnell, you did pretty good on the last flight, let's make this one even better. Is everything ready? Yep! Then give the GO signal! Now hold back, take a couple of steps, and we're airborne. Everything's looking good. Be careful not to get too far to the left or the glider might do like it did last time and try to turn to the left, starting another over-control oscillation. Yes, that's right, let the glider drift slightly to the right - down wind.

Watch out! You're over-controlling again. Relax and let the glider stabilize. That's better. The climb rate is just about right. Altitude is about 200 ft. Everything seems to be going good. Watch it! You're over-controlling again. Relax! That's better.

WHAM! What's happened? Something broke! The glider's out of trim! Oh, it's nothing - the keel latch just released prematurely. But the nose is too high and the glider is trying to climb too fast. The towline force is increasing! Pull the bar in fast! Uh Oh, too late! You broke the weak link! (NOTE: The driver had noticed the tension increasing earlier, and by this time had completely stopped the vehicle. Apparently a pocket of higher velocity air had raised my nose, caused a premature release, and broke the weak link, all before I recognized what was happening and made corrections with the new glider.)

OK, then, let's drop the bridle and turn to fly back toward take-off. Now don't over control and turn too much. Ease your weight to the left. That's good. Now straighten it up. Your ground track is about right. Keep your speed medium slow. You don't want to stall the glider flying down wind, but you don't want to lose more altitude than necessary, either.

Hey, we're going to be able to make it all the way back to take-off! OK now, you don't want to overshoot and land in the bushes. Better begin your right turn back into the wind. That's good. Say, we're going to land right at take-off! Not bad for a beginner. Now if you can only keep from blowing your landing. Here comes the ground. Start your flare. Touchdown!

The wind's pretty strong, better get that nose down and unhook before something happens. Say, except for breaking the weak link that was a pretty good flight. With a little more practice, you might actually learn to fly this machine. I wonder if we'll have time for another flight today? The sun is getting a little low.

It turned out that there was not enough time for another flight that day. Normally, when the weak link breaks, I wait until just before landing before dropping the bridle in order to reduce the height of the freefall and to make it easier to find. But in the excitement of the last flight, I dropped the bridle right after the weak link broke. As a result, we spent almost 30 minutes looking for it. By the time we found it embedded in the dirt after the 250 ft fall, the sun was getting so low that we had to start putting things up. It was completely dark by the time we left the airport.

THIRD FLIGHT

It was four days later, Saturday, before I had another chance to fly my new Gemini. This time the winds were NE at 8 to 10 mph. Instead of going back to the County Airport, we went to an alternate air field which we call "South Field". A portion of this WWII air field was donated to the county a few years ago by the US NAVY. The rest of the field is still part of the Kingsville Naval Air Station. A barbed wire fence runs through the middle of the field separating the two parts. The only time we can fly here is when the NAS is not operating and the jet trainers are not flying.

The main reason we decided to fly here this time was that we could tow beginning flyers directly into the wind here but would have had to tow them cross-wind at the regular site. Before I flew my Gemini, we had a training session where Mike Green made 18 short flights up to about 12 ft using my old standard Rogallo. After Mike finished, we set up the Gemini and the full 600 ft towline for my flights. The first of these flights went something like this:

The wind is coming straight in at about 8 mph and everything is ready to go. If we're careful, this should be a better flight than either of the two previous ones. All right, Donnell, give the GO signal and let's go. Keep the wings level while the towline under the base tube lifts the glider with its nose high. Tension's building up, let's take a few slow steps. Glider's flying. Faster now and we're airborne.

Everything's fine. This time let's remember not to over-control this thing. Just swing your feet to make minor course corrections. Nope, that's not quite right. Try again. Watch out, you are over-controlling again. Let the glider stabilize itself. What's this? We're flying sideways! Say, Donnell, apparently part of your problem has been a failure to recognize a yaw when you see one! There now, the glider has made its own yaw correction and is flying straight again. It's going to take a little more air time to get used to this yawing phenomenon and make the proper control responses. Your old standard tracks so well you've never had to learn about proper yaw control. Oh well, it's going to be fun learning.

Looks like we're reaching the 250 ft mark. Better watch that auto-release line lest it surprise you with another premature release. Yep, it's tight. We're likely to have a premature release at any time now. Be ready, just in case! But the van is nearing the end of the runway, so we're going to have to release pretty soon anyway. Let's do it now before it releases itself. There, we're free.

Now let's bank it to the left and make a 180 degree turn back downwind. Good, now let's experiment with a little speed control. Wow! This Gemini can accelerate pretty fast. OK let's slow it down closer to minimum sink or we'll not make it back to take-off. Control seems a little easier in free flight than while on tow. That's strange. I wonder if this is a real phenomenon or simply a mental illusion. If it's real, I wonder why? Theoretically the handling should be the same on tow as if a larger pilot were flying freely.

Get your mind back on flying, boy. You don't want to turn too late and land in the trees below. That could be bad! Perhaps it would be better to turn too soon rather than chance turning too late. After all, the glider may not turn like you expect. There, the turn is good. But we're coming in a little high. Looks like you could have stretched it out like you thought and made it all the way back to take-off. But this is no time to be considering what could have been. You have plenty of room on the runway, so let's just bring her down there. We're coming in a little fast, so we better not flare too much or we might climb up too high and stall. You're doing fine, now hold it and bleed off the speed. Say, when is this thing going to slow down? It's just floating and floating. There now, we're starting to slow down. Let's make our final flare and - touchdown.

Good flight! Of course, it would have been better if you had flown down wind a little farther and landed at take-off, but you probably did the right thing by turning early. It's always better to be safe than sorry.

FOURTH FLIGHT

While the ground crew was gathering up the towing equipment, I carried the glider part way back to the take-off point. I did not roll it back because we had not mounted the wheels on the control bar. Since we could not carry it back on the van without breaking it down, we decided to start our next flight, but by climbing a little faster, I was confident that I could reach an altitude high enough to make it all the way back to take-off. After all, I almost made it back on the last flight and I had climbed pretty slowly on that flight.

My fourth flight on the Gemini went something like this:

Good take off! Everything seems under control. The climb rate is about right (faster than the last time). OK, let's try getting the feel of this yaw control. Man, that's WEIRD! Flying in one direction while the glider's pointing in another. It's somewhat like crabbing in a cross-wind, but more temporary. Reminds me a little like a fish wiggling its tail while swimming through the water.

Enough of that. We're now approximately 400 ft high and the van is approaching the end of the runway. It should be slowing down soon. Yep, there it goes. The towline's starting to grow slack. Hey, wait a minute! You've let the glider turn too far to the right. You don't want to release in this position or the bridle might tangle with the flight wires. Better turn back to the left.

Uh oh, the towline is too slack. It's already touching the flying wire and the control bar. You better get off the towline FAST! Release!

OH NO! The keel latch fell back over the control bar. QUICK! Get it off of there before it becomes too tangled to release! LOOK OUT! The glider's banking hard to the right. As fast as this thing turns we're likely to find ourselves in worse trouble than ever if we don't get things back under control. Forget the bridle line for now and GET THIS GLIDER BACK UNDER CONTROL! All right now, you've got the glider back under control, what about the keel latch? On no, the bridle line is draped over the left corner of the control bar and twisted around itself! If you try to reach over and untangle it, you are certain to shift your weight and make the glider turn again. You could easily lose control again. But if you don't get that line untangled and it snags on the ground, the pull on the bottom corner or the control bar could cause the glider to crash right into the ground.

Donnell, you're in BIG TROUBLE! What're you going to do now, old buddy? I don't know, but this certainly is no time to panic. The most important rule of flying is to KEEP THE GLIDER UNDER CONTROL, so that's what I am going to try to do as long as it is physically possible. If I am able to do this all the way to the ground, then I'll be all right.

The second thing I must do is think as fast as possible and try to determine the safest possible flight path I can take. I don't dare turn appreciably. This would drag the towline around in circles causing it almost certainly to snag on something. Fortunately we are flying over this asphalt runway complex, so if I am lucky the line won't snag. I hope the ground crew has unhooked the line from their end. (They had!)

Man, we're coming down fast! Oh yes, we're pulling a 3 ft drag chute behind us. Glider control is fine, though. But at this rate we are going to land over the barbed wire fence and on the NAVY'S SIDE OF THE AIRFIELD. In an emergency like this, I'll take my chances with the NAVY and go ahead and land there.

But wait a minute, Donnell, you're dragging a parachute and towline behind you. What if one or the other snags on the barbed wire fence? You're DEAD! And at the rate you're coming down, that just might happen!

That's right, I better change my plans. But there isn't much time. I'm only about 100 ft high now and coming down fast. If I turn just slightly to the left, then I should be able to pass just slightly to the left corner of the barbed wire fence. Then I will be dragging the towline over nothing but the asphalt runway.

OK then, let's do it! Not too radical a maneuver now, we're getting close to the ground. There's the corner of the fence directly below us about 30 ft. If the slight cross-wind blows the line to the left, things will be all right. If not - well, we'll know pretty soon. In any case, we better assume the line does not snag and start setting up our landing approach. That ground is coming up pretty fast!

Keep your speed up, you don't want to stall with this parachute dragging along behind. Turn the glider back a little to the right so you'll be landing into the wind. Now you're coming in HOT, so get your hands as high on the control bar as you can so you can give it a good flare when the time comes. (This is not my normal landing procedure, but it is what the Gemini instruction booklet said to do in low wind, fast landing situations.) Here comes the ground. Get ready to start flaring. CRASH!!

I'm still not quite sure what happened. Putting together what I remember with what the ground crew saw, it appears that I did not flare soon enough and hard enough. Apparently the towline never snagged, but the drag of the parachute on the asphalt may have pulled back enough on the bottom of the control bar to prevent me from flaring properly with my hands so high on the downtubes. Or the faster than normal descent may have messed up my timing. But regardless of the season, my feet made contact with the ground while the glider and I were going too fast. I fell; the wheel-less control bar hit the asphalt; the glider nosed over; I slammed into the control bar; and I tore my pants beyond repair as my knees slid across the asphalt. (My knees were scraped fairly badly, but not seriously enough to require professional help.)

We still do not know the full extent of the damage to the glider, but preliminary inspection showed that the right downtube was broken, the left one was slightly bent, and the nose batten was broken. (Apparently the impact knocked it forward onto the pavement where it was caught under the nose of the sliding glider.) Of course, the basetube and the nose plate were scratched up pretty well.

Right now I am waiting for my knees to heal, and I plan to repair the glider as soon as possible. At that time I'll be able to see whether or not any more damage was done. But regardless of whether or not there was any additional damage, one thing is certain: this fourth flight is the last flight I'll make in my new Gemini. It's not new any more.
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DEAR DONNELL
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1982/11-02

BEST THEORIES

Dear Donnell,

Please send Skyting No. 1. I enjoyed articles in Whole Air and I think your theories are the best I've ever heard.

Jule Lorenzen
Galva, KS
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PLEASE USE WHEELS
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1982/11-03

Dear Don,

I have read SKYTING with great interest. Your application of physics and analysis of forces are impressive. I can find no fault with the principles as you present them. I do have one suggestion. Please urge all pilots using ground tow to have a good pair of wheels on the glider.

The USHGA requires all instructors to have wheels on the gliders that their students fly. In towing the same thing should apply to all gliders. We even put wheels on our Mega to tow it. If the pilot falls or faulters in the take-off run, the wheels save what would otherwise be a pair of bent down-tubes at least - frequently worse.

Here is our check for one Bridle, one Skyting Belt, and one Keel Ring and for the issues of SKYTING that you sent earlier. Keep me on your list. We will keep you informed of our progress. We teach about 30 students a year, almost all fly our Yarnall winch several lessons including the first. We want to try high towing with the skyting rig. We will be using a Flight Designs 175 Demon and a UP Comet OVR for high tows. We use Flight Designs Sabres for training gliders.

Birch Phillips
Williamsport, PA
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1982/11-04

Note:

If I had been using wheels on my last flight, my Gemini would still be new. Need I say more?

Ed.
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1982/11-05

NEWS

(The following information was taken from the WIND WRITER, Journal of the Houston Hang Gliding Association. Whenever you find similar articles, please forward them to me. Ed.)

TOWING IN HOUSTON

BOB LOUDERMILK reports LOTS OF SUCCESSFUL TOWING recently, with his winch system, coupled with The Hewett Release System. A couple weeks ago, Bob and B Asher were practice-towing to 200 feet (winch being pulled by vehicle). Bob invites other pilots to try out the towing. "Get your own necessary equipment together, if you're interested," he says..."you need a strap for your harness, a connection point on your keel, and a 2-way radio." B claims that all tows are going very well and that it's an easy, safe system to learn to tow-fly with.
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1982/11-06

GUIDELINES FOR TOWING HANG GLIDERS

(The following material was submitted by Sandy Francisco of the Tidewater Hang Gliding Association, Virginia Beach, VA. Although these guidelines were developed for conventional towing, they are well thought out and contain many good ideas appropriate to skyting or modified skyting systems. If you or your club has published similar information, please send me a copy. By sharing what we each of learned, our own knowledge and safety is increased. Ed.)

(The following material was submitted by Sandy Francisco...)

Due to recent increases in hang gliding towing at inland sites, brought about by the availability of several types of tension limiting stationary powered winches, our club thought it might be useful to the hang gliding community if we shared some of our experiences and information.

Our club, the Tidewater Hang Gliding Association, has been towing at several sites in southeastern Virginia, ocean and inland sites. We have developed a set of guidelines, (which are included) that have been working very well for our organization. Several new clubs are evolving centered around towing activities, and hopefully these guidelines will be of some use to them.

The first part of the guidelines deals with wind conditions. This is probably the most important aspect of towing safety. Our experience indicates that the higher the wind speed and turbulence, the more probable it is that the pilot will have control problems. The values we have used in our guidelines are purposefully conservative. The chances of rolling or pitching to an undesirable attitude are greatly reduced in dead calm air, and this is the safest condition to tow in. Flying in winds above 10 mph at inland sites under tow can require significant skill and quickness. The probability of encountering turbulance of sufficient magnitude to cause loss of control or a lockout increases with the square of the wind velocity at inland sites.

Because the weight of the aircraft we tow are relatively small, and the wing loading so light, airframe accelerations can be (relative to other types of aircraft) very high. This is why smooth air is so important to safe hang glider towing. The flight dynamics of towing are different from those of gliding, due to the tow line forces which are restrictive on glider yaw, etc. Because this reduces maneuverability, it should also be accompanied by an increased amount of discretion from the pilot about wind conditions.

The most critical aspects of towing hang gliders occurs between launch and the first 200 ft. AGL. The pilot is flying in ground induced turbulance at this time, under tow, with a relatively high angle of attack w.r.t. the horizon, and in close proximity to the ground. Early recognition and correction for undesirable flight attitudes (roll, pitch, or yaw) is important for both the pilot and winch operator.

To aid a fast release from the tow line when required, our club recommends that the release mechanism handle be located on the control bar, so as to allow the pilot to actuate the release quickly, without relinquishing control of the glider.

Another point of safety interest is the release stall. Most gliders will pitch up after an abrupt release from the tow line under tension. We advise our pilots to lower their glider nose to it's normal gliding attitude before releasing. This helps prevent stalls, tow line snarls, and promotes a smoother transition from towing to gliding modes of flight.

Finally, it has been our experience that gliders under tow tend to roll into lockout situations as opposed to pitching or yawing into a lockout. Therefore, our winch operators are instructed to cut power if any glider is observed to roll past 20 degrees while under tow. This alone has all but eliminated lockouts from our club. We hope this information will assist other towing pilots and clubs.

RECOMMENDATIONS SUBMITTED BY THE TOWING COMMITTEE FOR CLUB SANCTIONED TOWING ACTIVITIES.

The following outline pertains to towing on the low tension powered stationary winches.

A) Conditions:

1. Any pilot's first tow should be done in 0 to 5 m.p.h., stable winds.

2. Second to tenth tows can be done up to 7 m.p.h. winds.

3. Eleventh to twentieth tows can be done up to 10 m.p.h., moderately turbulent winds.

4. Over 25 tows logged: winds in up to 12 m.p.h. max. peak velocity, with moderate turbulence if the pilot holds a current USHGA intermediate rating, and meets other requirements as stated here and in the association constitution.

5. Tree lined sites must be at least 350' wide. Non-bordered fields must be at least 150' wide.

6. No first tows are allowed during public demonstrations unless the pilot is USHGA Hang III rated, with tow skill endorsement.

B) Pilot Qualifications:

1. All tow pilots must have a current USHGA Hang 2 rating or better, and must be current members of the T.H.G.A.

2. All tow pilots must observe the towing operation from both ends, prior to their first tow flight.

3. All pilots should be familiar with all back up systems and emergency procedures as outlined herein.

4. Pilots must have logged 180 degree turns to qualify for tows to altitudes which require downwind flying.

5. It is recommended that all pilots learn how to operate the winch.

6. The last turn on final approach should be completed at least 30' AGL.

7. Spectators should be clear of operational areas; the launch director is responsible for this.

8. Pilot's meeting should be conducted to discuss peculiar parameters before towing.

C) Equipment Qualifications:

1. Wheels are mandatory for a pilot's first 5 tows, and strongly recommended thereafter.

2. Release handles must be attached to the control bar tube nearest the pilot's hand during the tow.

3. All control bars must be in perfect structural condition.4. All release mechanisms must be in perfect condition.5. No standards or non-production gliders will be towed.

6. A B.U.S. is recommended for tows to altitudes above 200'.

7. A suitable knife should be available to the winch operator in case of emergency.

8. The landing area should be clearly marked with a windsock.

D) General:

1. When in doubt, the winch operator should always cut power.

2. Pilot and glider must be clearly visible to winch operator.

3. A minimum of three persons is required to tow: pilot, launch coordinator, and winch operator.

4. Winch operators must be qualified through instruction with hands on training.

5. Never touch a moving tow line.

6. All pilots must sign a disclaimer before towing.
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*

1982/12
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SKYTING NO. 8
December 1982
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1982/12-01

POSSIBLE SOLUTIONS TO THE TANGLED BRIDLE PROBLEM

by Donnell Hewett

In my opinion the most dangerous aspect of skyting is the possibility of having the bridle tangle with the glider's control bar (or some other part of the glider or pilot). Although this rarely happens (especially if the pilot is careful), and although, even if it does happen, the bridle can usually be untangled in flight before the situation becomes very dangerous, there is always the possibility that the bridle can become tangled so badly that the pilot cannot possibly release himself from tow. Such a situation could be catastrophic if the towline happens to snag on the ground as it is being dragged behind the glider.

In my own experience I have had the bridle tangle several times. Most of these entanglements occurred several years ago when skyting was being developed. But my most recent entanglement occurred just a few weeks ago. (See SKYTING NO. 7.) This experience has served to remind me to try once again to find a satisfactory solution to this problem.

This article describes several possible solutions to the problem. Some of these methods have been tried or proposed previously by myself or others, but some of them have never been mentioned or attempted. Indeed, some of the proposed actions are so dangerous that they should never be attempted under normal flight situations. They are mentioned here only because in a truely desperate situation they might help save someone's life.

Ten possible solutions to the tangled bridle problem are described below. The first four of these solutions attemp to prevent the bridle from ever becoming tangled in the first place. The next two solutions deal with getting the towline free after the bridle has become tangled. And the last four consider what to do when it is impossible to get the bridle untangled.

1. NEVER AUTO-RELEASE A KEEL LINE TOUCHING THE GLIDER

It is almost impossible for the bridle to become tangled with the glider unless it is already touching the glider when the release attempt is made. Although a good pilot tries to prevent the bridle line from ever touching the flying wires or control bar, there are two situations where it can happen: (1) a gust of wind can turn the glider crossways so far that the keel line touches a flying wire, or (2) the towline becomes slack and is blown back against the control bar. Of these two situations, the second is most likely to result in a tangled bridle. This is because (1) the pilot is more likely to try releasing from a slack towline than when experiencing a cross-tow situation (where he is too busy flying to try releasing), and (2) a slack towline is more likely to fall over the control bar than the tight line of the cross-tow situation because the tension in the tight line tends to pull the falling keel latch away from the glider before it has time to become tangled.

So what should a pilot do when he encounters one of the above solutions? In the cross-tow situation, he should concentrate on turning the glider back where it belongs. And in the loose towline situation he should release the keel latch manually before releasing the body latch. In other words, instead of releasing the body latch first and letting the auto-release line release the keel latch, the pilot should reach up and release the keel latch by hand (making sure that it does not become entangled) and then reach down and release his body latch.

If I had followed the above procedure, the tangled bridle incident described in the last issue of SKYTING never would have happened. You can be sure I will follow this practice in the future.

2. USE AN "EXTENSION LINE" ON THE BRIDLE

Although I have never tried it, I have often considered the idea of attaching an extension line between the keel latch and the keel ring of the glider. If the line is longer than the control bar, then the keel latch will always be below the flying wires and control bar and cannot possibly tangle with the glider or pilot when released. Of course the length of the bridle lines and the auto-release line may have to be altered for this system to be trimmed properly.

There are several possible disadvantages in using this system. (1) The extension line stays with the glider and may sometimes get in the pilot's way. (2) The extension line stays with the glider and may sometimes fly back in the pilot's face upon release. (3) If the auto-release mechanism fails to work, the pilot may be unable to reach the latch for a manual release. Perhaps this is the last problem could be solved by having another latch at the top of the extension line so that it could be released from the keel by hand.

3. FLY ON BODY LINE ONLY

One obvious way to prevent the keel line from tangling with the glider is to not use one. I know of at least one pilot who practices this policy exclusively and several other pilots who use this method after their initial climb while "peaking out". When using this method no part of the brilde line touches the glider, even if the cross-tow angle is as great as 90 degrees or more.

However, as pointed out in SKYTING NO. 1, this system results in the glider being flown out of trim. Specifically, the tow force is pulling below the pilot-glider center of mass and tends to cause the glider to pitch up on a straight tow and roll out on a cross-tow situation. This increases the tendency to climb on a straight and the tendency to lockout on a cross tow. In other words, the glider is harder to control, but the loss of control is more of an inconvenience than a real danger.

4. USE A YARNALL TYPE OF RELEASE

By placing the release mechanism between the bridle and towline (with the activation lever on the control bar), the tow line cannot possibly become tangled with the glider. Of course, this does not prevent the bridle from tangling with the glider or pilot, but it does prevent the towline from dragging along behind the glider and possibly snagging on the ground. There are other advantages to this system: (1) the Yarnall release mechanism is probably more reliable than the standard skyting latches (Actually, I have never seen a Yarnall release system, so I am assuming this to be true.), and (2) the release activation lever is on the control bar. This enables the pilot to release without taking his hand off the control bar. (Some pilots strongly prefer this characteristic in their release system.)

The major disadvantage of using the Yarnall type of release system is the fact that the bridle stays with the glider after release. It can fly back in the pilot's face when released. It can become tangled with the pilot or glider during flight. It can trip the pilot when landing. It can snag on the ground when landing. And if used on cross country flights, it will cause more aerodynamic drag. One way to reduce some of these problems is to use a bungie cord or other mechanism to pull the bridle up out of the way after releasing. (The British have been known to use this technique. See SKYTING NO. 2.)

Another disadvantage of the Yarnall release system is the fact that it requires the pilot to keep his hand at one position on the control bar. This is all right under normal flight conditions, but it does prevent the pilot from safely switching back and forth from prone to erect flying and from moving his hands from side to side on the control bar while flying.

5. GET UNTANGLED

If after taking one or more of the above precautions, you still find yourself with a tangled bridle, the obvious thing to do is to try to get it untangled. Sometimes this can be accomplished by simply reaching over and untangling the mess while in flight, just as you would if you were on the ground. The problem here is that you need to be a pretty good pilot to accomplish this without simultaneously losing control of the glider.

Of course, if you have plenty of altitude, you might be able to afford to sacrafice a little glider control in order to get the bridle untangled and then regain total control after getting untangled. For example, if your glider can be flown "hands off", you can simply let the glider fly itself while you use both hands to untangle the bridle.

6. DETACH BRIDLE FROM TOWLINE

If the bridle cannot be untangled while in flight, the pilot may still be able to lift the bridle line up until he reaches the towline leader. If a manual release mechanism has been place at this location, the pilot can then release the towline by hand.

Another way to accomplish this is to use a cable activated release at this point and clip the release lever to the control bar in such a way that under a normal release situation everything falls away from the bridle, but in an emergency situation the release lever can be activated to separate the towline from the bridle. Such a release system would act like a Yarnall system in an emergency and like a standard skyting release under normal circumstances.

7. USE A PARACHUTE

If the bridle cannot be untangled or the towline disconnected, there are still certain things the pilot can do to improve his chances of survival. One option is to deploy his parachute. Even if the towline snaggs on the ground, this situation should be no more dangerous than other parachute deployment situations.

8. FLY STRAIGHT

If the ground crew releases their end of the towline, the flight path least likely to cause the towline to tangle with the ground is a straight (or reasonably straight) path. Turns tend to drag the towline sideways and increase the chances of it snagging on something.

This is the technique I used the last time my towline became tangled. Never-the-less, I do not like to use this technique because there is always the possibility of a towline snagg.

9. SPIN TO THE GROUND

If the towline does not actually snag on the ground, the pilot has little choice but to bank the glider over into a tight turn and keep it there until just before landing. The towline should simply coil up in a circle below him.

The main danger in using this technique occurs at low elevations. When the pilot straightens out to land, he is going to start pulling on the coiled rope and if there is anything in the center of the coil, the line will snag on it for certain.

Of course, if there is any significant wind, the pilot must make the proper compensations to make the rope coil properly. He must also time his descent carefully in order to keep from having to land down wind.

To be honest, I hope I never have to try this technique - it sounds dangerous to me.

10. GUIDE LINE TO THE GROUND

There is one last technique that you might be able to use if the towline should actually snag on the ground. When the snag occurs, the glider will probably nose over into a diving turn. If there is sufficient altitude to recover from the dive, then you will probably find yourself flying back where you came from. By keeping your eyes on the snagged towline, you may be able to guide the line back to the ground. The technique would be similar to taking a string in your hand and, as your hand descends, you guide the string where you want it to fall.

About all I can say here is - good luck!

This article has been written to stimulate thought and discussion on this important topic. If you have additional suggestions for solving this problem or comments you want to make on my suggestions, please send them in. If we can solve this problem before someone gets killed, it would be to everyone's benefit.
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PROBLEMS WITH THE SKYTING RELEASE SYSTEM
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1982/12-02

Dear Donnell,

I am writing to you about my towing experience since I expect that you are interested in any feedback about use of your skyting bridle. First some background info. I have about 150 winch flights using a Yarnell winch and Yarnall bridle and have observed thousands of tow flights over the past two years. Having learned flying on a tow system I never had the fear that some people have about lockouts but was always on the lookout for a means to eliminate the problem. As soon as I read about your bridle system I thought "now this is obviously the right way to go". It's always amazed me that no one ever sat down and thought about the physics of the problem, since it's really pretty simple. I suppose its just a case of "well this is the way you do it, don't ask any questions".

Well I have now had about 15 flights on the new bridle and about five days of observation of it in operation and can say that I really learned a lot. First I have to admit that the lockout problem definitely seems solved. (Actually, I observed one flight where the pilot got into what appeared to be a lockout but released immediately without trying to correct it. This was caused by a stall during the tow where one wing stalled first, putting the pilot in a very bizarre attitude.) This bridle really makes the tow seem like free flying rather than the wrestling match it was previously. Here are my comments about what I have learned:

Pilots used to other towing systems will over correct during the tow. In my own case my first flight was terrifying. This was also the first time I towed my Duck and the flight was marked by uncontrollable yaw oscillations. I believe if I wasn't wired into the hard corrections needed for the old system and had more time on my Duck this probably would not have happened.

The release mechanism is dangerous, again this may be because of old habits since virtually all of the pilots I observed were experienced tow pilots. Let me relate the problems I have seen.

The top release hit three pilots on their helmets very hard. In two cases this was caused by the pilots releasing nearly directly over the winch. In the other case the release was done with the nose high.

The top release, when released under low tension, dropped and wrapped around the control bar and flying wire of two pilots. This caused no problem since power was cut and the pilot simply untangled it.

The top release choked two pilots by wrapping around their necks. This happened when release occurred with the top tow line on one side of the pilots' head and the top release string on the other side of the pilot. This was very frightening to the pilots involved since the winch power was attempting to pull them out of their harnesses. Plus, they had very little control while this was happening. Fortunately power was cut immediately and they untangled themselves.

The bottom release injured fingers of four pilots who were unlucky enough to not be able to move their hand out of the way quickly.

In a desperate situation it can be difficult to release, which happened to me twice. In the first incident, as I said earlier, I got into violent yaw oscillations. There was no way that I could let go of the control bar and pull the release. In the second case, due to winch operator error, I was "launched" on the "cut" signal, I was not even holding the glider, and when the winch started I stumbled and was dragged. Once this happens you can't get to the release and you have to depend on someone cutting the power.

After all of this you may think that I have a bad attitude about skyting. Nothing could be further from the truth. I will never tow with a conventional bridle again. I don't intend to tow with an unmodified skyting bridle either. My plan at the moment is to place a Yarnall Release at the juncture of the tow line and the skyting bridle, with the release handle mounted on the control bar. Because of this the bridle will remain attached during flight. This is unfortunate, but it seems unavoidable. One of the things I like about the skyting bridle is that it all leaves, but the manner in which it leaves cancels the advantage in my opinion.

With the release mounted on the control bar I believe that the pilot has a better chance of releasing in an emergency (fortunately the new system reduces the frequency of emergency releases). This will probably bring up the debate of pilots being killed on conventional tow systems by their not being able to get to the release. Unfortunately, I was present when one of these accidents occurred. The president of our local club, Danny Cudney, was fatally injured, and a flier in South Carolina had a similar accident. I think that the wrong lesson may have been learned from these cases. In Danny's accident the release was mounted on his downtube (despite comments that this was unsafe). When the lockout occurred Danny was trying to correct and was as far as he could have been from his release. In S.C. the release was on the control bar but the pilot's hands were on the downtubes. I think this points out the problem. A release that requires the pilot to move a hand some distance to get to it will not be released in an emergency.

Also it seems to me that by not having the release leaving the glider the top tow point can be moved back to the glider's center of mass. It seems that the skyting bridle is attached forward of this to avoid hitting the pilot every time he releases. By moving the tow point back I hope the yawing problem will be reduced.

I hope you will respond to this letter because I believe interaction will be helpful in producing even safer towing in the future.

Steve Goldman
Cary, N.C.
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1982/12-03

Dear Steve,

Thank you so much for sharing your skyting experiences with us. I am convinced that such an exchange of ideas and information will help bring about safer towing methods. Some of the problems you mentioned are new to me, although most of them have been reported and discussed in previous issues of the SKYTING Newsletter. If you are serious about sharing experiences, you should subscribe to this newsletter.

By the way, since I have no record of communicating with you previously, I cannot help wondering where you learned about skyting theory and where you got your equipment. I am also curious as to whether you tow over water or land (I assume over land); whether or not you use a weak link (I assume you do not); how high you are towing (I assume more than 200 ft); and so forth.

It is too bad I could not have been there when you were learning to use the skyting system, perhaps I could have helped you avoid some of your more frightening experiences. I would also be in a better position at this time to make comments about what happened. But please allow me to make a few comments anyway.

In the first place, I agree that it is a shame that no one applied the principles of physics to the hang glider towing operation before I did. But it seems a bigger shame that after applying these principles, the only way I could get the theory published was to do it myself. As a result, today - more than three years after the theory was developed - most of the hang gliding community is still unaware of its ramifications. Even now it is doubtful that the USHGA would publish the theory because there are still too many practical problems that have not been worked out. (Your own experience illustrates this fact even though you have not made full use of the skyting literature which was available.)

You are correct, lockouts are no longer the problem they used to be when towing with conventional systems. Other problems (although less severe) are still with us, however.

From what other pilots have reported, it appears that you are also correct in believing that pilots used to other towing systems will over-correct during the first few skyting tows. Apparently it is also true that certain gliders experience the adverse yaw problem more than others. Please let me know if you continue to have such problems with your Duck.

From your description of your experiences with the skyting release system, I can understand why you are dissatisfied. Please continue to seek a system that better meets your needs. You may also want to communicate directly with others who are persuing a similar course of action. (Note the Dear Donnell letters in back issues of SKYTING.) However, as you develop your system, please remember the "skyting criteria": (1) constant tow direction, (2) constant tension, (3) proper distribution of tow forces, (4) proper attachment points, (5) gradual transition to and from tow, (6) reliable release, (7) infallible weak link, and (8) a safe learning method. In my opinion the closer you come to meeting these eight conditions, the safer your towing system will be.

Now concerning your release problem, I would like to make a few comments. You said three of your pilots were hit on the head during releases. How did you prevent this when towing conventionally? (You probably released the top line before maxing out.) You could use the same technique while skyting! You could also prevent this problem by simply rotating either the glider or the pilot's body (or both) slightly to the side so the pilot's head remains always clear of the bridle line.

In my opinion, the most dangerous aspect of the skyting bridle which you mentioned was the situation where the bridle tangled with the control bar after a slack line release. The two pilots you mentioned who experienced this problem were fortunate to untangle the mess before something snagged on the ground. You will notice my similar experience in SKYTING NO. 7. I plan to discuss this problem and possible solutions in the next issue of SKYTING.

I can appreciate the problem of having the bridle line wrap around the pilot's neck during a release. Although I have never experienced this, one of my flying buddies did - several years ago when we were first developing the system. Once the problem is recognized, however, the solution is quite simple: simply make sure the bridle line and auto-release line are both on the same side of the pilot's head at all times. Again, this is most easily accomplished by flying slightly to the side of the tow direction and, if necessary, rotating the body slightly to the side of the tow direction and, if necessary, rotating the body slightly to get the head and shoulders out of the way. The only time this is hard to do is when significant traversing is being done at high tow angles, so the line is first on one side and then on the other and must "pass through the pilot's body". As long as the tow angle is low or the pilot stays on one side of the vehicle, there is no problem. If the tow angle is large, the pilot can simply release the top release first, and do his maneuvers while towing with the body line only.

The fact that four of your pilots have injured their fingers while releasing indicates that you make it a practice to release while under full or near full tension. This is a violation of skyting criterion No. 5. If you want to continue this practice you will certainly have to change the release. When the tension on the release becomes much greater than 100 pounds, then (1) the release becomes hard to activate (and at high enough tensions it may even fail to release), and (2) when it does release, it shoots through your fingers like a bullet. To prevent such excessive tensions from ever occurring, we use a weak link. We also make it a practice to reduce the towline tension before releasing. As a result, we hardly ever experience a "sore finger" release.

You mentioned two cases where you found it hard to release. I believe the first one was simply a lack of experience on your part. The oscillations you described were obviously the result of over-control, not under-control. Although you may not have thought so at the time, you certainly could have safely relinquished some of your control to activate the release.

The second situation you mentioned was the result of violating skyting's criterion No. 5. (Again!) When the winch started up, the tension increased so fast you could not react fast enough to release.

With the system as we use it, if the car had started up, the tension would have gradually increased while the elastic towline stretched. Feeling this happen, the pilot probably would have had time to release, lost his balance, and fell on top of his release mechanism, the weak link would have broken before he was dragged by the vehicle. This is an example of what I was warning people about in my very first article on skyting when I said, " ... it should be mentioned here that skyting consists of the whole package. Eliminating any one of these elements, or substituting any one of these elements, or substituting one or more of them into an existing conventional towing system may well result in a situation considerably more dangerous than the original."

You mentioned the possibility of moving the keel attachment point farther back to the hang point. There is nothing wrong in doing this. In fact, theoretically, that is where it should be in the first place. The reason for moving it forward is simply one of convenience. By doing so, the bridle line and release mechanism are placed farther out of the way of the pilot's head during take-off, tow, and release. (Primarily during take-off.) With the larger control bars on the more modern gliders, it appears possible to move the attachment point farther back without undue interference. I do not know whether or not this move will help correct the adverse yaw problem, for I do not really understand what causes the adverse yaw problem. (Perhaps now that I am beginning to experience this problem with my new glider, I will take the time to analyze the problem more fully.)

Thanks again for the feedback, and I hope my comments are helpful. Please let me know if I can be of further service.

Donnell
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PROBLEMS WITH WATER TOWING
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1982/12-04

Dear Donnell,

October 10, 1982, I boat towed skyting over Lake Delta, Rome, N.Y.

I mailed you a check for your bridle on Monday 10/4 and received the bridle on Friday 10/8. This must be a record. Rome, N.Y, to Kingsville, Texas, and back in five days! I thank you very much for your prompt handling at your end. I also must say that I am pleasantly surprised with the U.S. Mail's prompt delivery... could this be a trend?

I had worked all week preparing for our first day of towing in my front yard, the lake. I built a pair of control bar floats, a keel float, and a static line boat release fashioned after a Dyer in line release. Everything was ready when the bridle came in on friday.

Saturday, myself and Dan Guido, a Hang IV and instructor from Mohawk, N.Y. 35 miles from Rome, spent the afternoon in final preparation.

Both Dan and I had received a day of tow training at High Perspectives in Toranto, Canada, on 9/21/82. We used a traditional V-bridle with two releases, one at the heart bolt and the other at the control bar. I was a "hot" Hang I pilot with about 7 minutes of air time. At the end of the day we had both winch towed to 2,000 ft and I had gained 35 minutes of air time - moving me close to my Hang II. Thats our experience with towing.

Sunday, October 10, at 11:00 we hit the shore line. Boat, release, towline, bridle, the Bobcat II on a three point float system and us in wet suits. We are starting in the water using a prone harness. The control bar is suspended about four inches above the water by the control bar floats, the tail supported by the keel float.

What happened next is a long story. We were in the H2O from 11 am till 3:30 pm.

Dan went first, a slow pull to get the glider just moving - hit it! The glider slips out of the water, climbs to about 50 ft., the top line releases! WHOA! Dan releases the body release and glides back down. Dan was impressed with the response of the glider using the Skyting Bridle but not with the premature release of the top bridle line.

When the boat circled and brought the bridle back to the glider and pilot, it was a tangled mess. The hose on the releases acted like a fishing lure and caused the bridle to twist and tangle when pulled through the water. We had to tow Dan to shore to untangle the bridle and to lengthen the auto-release line.

Dan had three more flights between 100 ft and 150 ft, none were completed without premature release. I was driving the boat and could watch Dan and control the boat speed at the same time. This allowed me to back off quickly so that Dan didn't get into any real trouble because of the unplanned releases.

We determined that at high tow angles the auto-release line was being pulled so we lengthened it further.

My turn. Take off one wing sticks in the water, the glider yaws 60 degrees, the boat man releases ... too bad, I was just bringing it back ... I had control even at this radical angle.

This was quite a difference - a positive improvement over the traditional system's responsiveness.

After untangling the bridle (what a pain when your in the water), we were ready for my second try. The glider again yawed about 40 degrees on take-off but I corrected with no difficulty. The roll and pitch respons is sensitive but very welcome. While climbing out the top release went again! The boat man releases. I experience just a slight stall and glide down and land. The landings, by the way, are the greatest. You come in just like a sea plane and touch down gently skimming on the water's surface.

Back to my second flight. After landing I could not find my body release. I didn't release it. What happened? For some reason the body release activated after the boat release. Why? Possibly recoil from the tow line being released from the boat?

On my fourth tow I was climbing out quite rapidly, holding the bar in. Why? Lines twisted? As I began to signal the boat to slow down - POP! - the top release opens, the glider pitches up. The boat driver was not watching at that moment (we learned the driver (throttle man) must keep visual contact with the glider at all times controling the throttle. Someone else will steer the boat) and therefore could not respond to the situation. Just before I was able to release the body latch - POP! - the boat release breaks under the force of the glider's drag while its pitched up into a vertical position.

I'm in big trouble. At about 150 ft I am hanging motionless with the nose of the glider pointing straight up. A second later I find myself in a vertical luff dive, heading straight in. I couldn't believe how calm I was. My first thought was "I wonder how hard I'm going to hit the water." Second thought, "Don't push the bar out too soon, let's get some air speed ... now ease it out a little ... a little more. At 20 ft above the surface the Bobcat levels out and glides to a perfect landing.

I'm glad that Linda, the driver, didn't see what happened between 150 ft and 20 ft. Linda is my wife.

Needless to say, we packed it in for the day.

Dan and I were very excited about the positive flying characteristics the skyting system provides in contrast to the "Hang on for dear life and correct quickly or else" characteristics of the traditional towing system we used in Toranto (EMMERSON-BAILEY). We also knew we had work to do if the system was going to release reliably and the bridle was going to be kept from tangling.

We decided to keep the skyting bridle attached to the glider and pilot and release the tow rope from its point of attachment to the bridle. This one release would be cable activated by a lever on the control bar. This would give the pilot positive control of the release and solve, for us, the bigger problem of tangled bridle lines. The only draw back we could see was the bridle would stay connected to you and the glider during free flight. We then figured that this nuisance could be minimized by retracting the bridle up to the front of the keel and removing a carabiner used as a body latch and hanging it on a ring connected to a down tube or some suitable place.

I modified one of your releases so that it could be cable activated and located at the front of the bridle. I then ran a cable back and clamped the activating lever to the control bar. The cable action must be very positive. I first used a 10 speed cable and lever which had to much play. I finally used an outboard motor shift cable and a motorcycle break lever which worked very well.

With the cold weather quickly approaching I had no time to find and install a retracting device. We didn't think this was critical at this stage anyway, so we were ready to try the modified system.

Wednesday, October 20th, we hit the water again. Dan couldn't make it so I went with a crew of fellow water skiers.

Because of a 25-30 mph wind, I was limited to flying in the lee of a tree covered ridge at my end of the lake. Not a good situation, but it could be the last 60 degree F day we might have and the lake water's temperature was getting mighty cold. I know that rotors and wind gusts would be a problem, so I planned to keep to a maximum of about 10 ft of altitude.

The system worked well, the release worked perfectly everytime, the bridle did not tangle, and reconnecting the tow rope in the water was no problem.

The day ended rather abruptly on my fifth flight. A cross-wind gust hit me on take off and gently rolled me and the glider over ... king post down! Oh, well. The floats kept everything on the surface and it was then only a slow tow to shore for the righting. This was a learning experience in itself.

I am confident that the skyting system has been successfully modified to meet our needs. I look forward to using it next summer to winch tow to cloud base 2-4000 feet.

I'll keep you informed of our progress. Thanks again for all your work in the field of towing.

Don A. Boardman III
Rome, NY

P.S. Let me know if there is any interest in the design of the control bar floats or release modification. I'd be glad to share the details. The floats are fashioned after a High Perspectives design that they worked on for several years. They work great to get the glider on plane and for landing.
*
1982/12-05

Dear Don,

Thank you for your very interesting letter and your willingness to share your experiences with others. I am sure that others will find your boat towing experiences informative. For example, I had never anticipated the problem you mentioned where the bridle line became tangled as it was pulled through the water. Although others have apparently boat towed with the skyting system, no one has reported this problem or mentioned how they solved it.

Once more I apologize about the premature release problem you encountered. This problem, its cause, and its solution were discussed in SKYTING NO. 6. I do not know whether or not you received this issue before your flights. Of course, pre-mature releasing should be no problem on your modified bridle system. Let us know how things look after you have gained more experience with the modified system.

I must say, you certainly had some experiences which others would not wish to repeat. This is particularly true concerning your "whip stall" experience, I am glad you are letting others know that this happened once. Perhaps they can now take the necessary precautions to see that it never happens again. (The next time, somebody could really get hurt!)

You now realize the importance of having the throttle man keep visual contact with the glider at all times. (Actually he should be watching the pilot and not the glider.) This is why we, who land tow, always require a minimum of two persons in the tow vehicle - one to drive and one to spot. It is essentially impossible for one person to perform both jobs adequately. In your case, you will need someone to steer the boat while the throttle man watches you.

Please allow me to voice my opinion of what happened to cause your "whip stall" and make some suggestions as to how it can be prevented in the future. From your description of a rapid climb rate and the difficulty you had in holding the bar in, it appears that you were being towed too fast. There are several things you can do to reduce the chances of this happening again. (1) In the first place, you need to learn to recognize the phenomenon sooner so you can send the appropriate signal to the ground crew. (2) The most elegant and costly method of solving this problem is to use a good tension limiting winch or reel. Such a device would feed line out at the desired rate regardless of how fast the vehicle was moving. (3) We use a tension gauge to inform the driver that he needs to slow down (or speed up). (4) Probably the easiest solution is to install an air speed indicator on the boat so the driver will know the approximate air speed of the glider. Of course, if there is a strong wind gradient, the boat's air speed and the glider's air speed will not be the same, but with practice, reasonable corrections can be make.

Since modern gliders are designed to pull themselves out of a dive, they try very hard to pull their nose up whenever they are flown too fast. This is what your glider did. And as the nose came up, the auto-release line (which was too short) tightened and caused a premature release. At the same time the force on the glider (above the center of mass of the system) increased. This caused the whole glider-pilot system to rotate nose up, increasing the glider's angle of attack, the load on the wings, and the tension in the towline. As the towline pulled even harder on the pilot and below the center of mass of the whole system, the nose rotated even higher and the whole effect was amplified even more. Under such circumstances, the forces can very rapidly exceed several thousand pounds. You were very fortunate that your boat release broke before one of your wings folded up or your hang strap broke in two.

Now you understand why we always use a weak link in our towing system. In a land towing system, this weak link would have broken long before the above situation developed. Of course, our weak link may be too weak for water towing because of the large forces needed to pull the pilot out of the water. But you could start with a weak link like ours and, if it breaks, continue strengthening it until it is the minimum strength required to pull you out of the water. Even if the weak link is too strong to prevent you from getting into some scary situations, it should at least limit them from being as bad as the one you just experienced. In any case, you can stop worrying about folding a wing while being towed.

You asked if we were interested in the design of your floats and the modification you make on the bridle. Diffinitely, yes, we are. One of the main reasons I have not already boat towed is that I did not want to take the time to design the necessary floats (nor did I know where to purchase a set). And I know of several people who have expressed an interest in placing the release lever on the control bar instead of on the body. If you have the time, please write us an article on each of these topics.

Donnell
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1983/01
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SKYTING NO. 9
JANUARY 1983
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1983/01-01

SKYTING Newsletter is published monthly by Donnell Hewett, 315 N. Wanda, Kingsville, TX 78363; (512) 592-6757. Price is $1.00 per single copy or $10.00 per year (U.S., Canada, &. Mexico) ($20.00 per year for other foreign subscriptions). Contributions of news, notes, articles, and illustrations are sincerely appreciated. All illustrations should be line drawings camera ready for photocopy reduction. All requests for return of material must be in writing and a self-addressed stamped envelope enclosed. Notification is required if contribution has been submitted to other publications. SKYTING Newsletter reserves the right to edit contributions where necessary. Neither SKYTING Newsletter nor its publisher assumes responsibility for the material or opinions of its contributors.
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1983/01-02

WHAT YOU CAN DO ABOUT SKYTING

by Donnell Hewett

Two years ago this month I submitted my first four articles on skyting to the Hang Gliding magazine for possible publication. Skyting has certainly come a long way since that time, and most of this progress is the direct result of the involvement of you who read this SKYTING newsletter. I would like to take this opportunity to thank you for your interest, encouragement, assistance, and contributions.

Considering what has happened during these last two years, there is little doubt that skyting (or something similar) will eventually become even more widespread than conventional hang gliding (mountain launched free flight). Many of skyting's potential forms have already been tried: land towing with a surface vehicle, water towing behind a boat, air-to-air towing using an ultralight aircraft, wind soaring from a moored line, launching with a stationary powered winch, tension regulation with a moving reel, and utilization of an elastic towline. Who knows? Perhaps some day such variations of skyting will become so popular that they will be known by their own names like "trailing", "trawling", "tugging", "kiting", "winching", "reeling", and "bouncing?", respectively.

Even people living near the mountains are becoming interested in skyting as they recognize its advantages in regards to training, towing rope soaring, and cross-country launching. Skyting even opens the door to mountain flying in those areas where mountain roads and mountain launch sites are unavailable or inaccessible.

So what can you do to help speed this day when such a variety of flying experiences are safely developed and readily available? Well, even if you are not inclined to explore now frontiers, there is much you can do.

1. You can begin by keeping yourself informed by reading every issue of SKYTING from cover to cover. If the newsletter is not meeting your need, if it is not worth the time it takes to read it, if it needs improvements - then let me know what is wrong and how it can be improved. Eventually, of course, as skyting becomes more popular, publishers more qualified than I are going to become involved. But in the mean time, let's try to make this the best publication on hang glider towing techniques (even if it is the only such publication).

2. You can encourage others to become informed about towing by reading your copies of SKYTING. Or better yet - encourage them to subscribe. (The more people who subscribe, the more you get for your money because of volume discounts in publication costs.) It really disturbs me when I realize that there are a lot of people experimenting with the skyting system who do not subscribe to the SKYTING newsletter. Obviously a lot of unnecessary mistakes are being repeated over and over. It is only a matter of time until someone gets killed while skyting because someone else told him enough to get started but not enough to skyte safely.

3. You can continue sharing your experiences, opinions, and suggestions with others by using this newsletter as a forum. Only you can supply the information which makes this publication truly useful to others.

4. You can encourage others to share their skyting experiences. Encourage your flying buddies to share what they have learned. The greater the number of people who contribute to this publication, the better it can become.

5. You can report what others are doing. Let's face it, some people will never write up their experiences, and I never hear about reports appearing in foreign magazines or local newsletters. I am almost completely isolated from the mainstream of hang glider activity, so the word of mouth communication which you may think "everybody" knows never reaches me unless one of you writes me or phones me to let me know. It is better to receive several reports on the same thing than not to receive any at all. Those of you who live in foreign countries and other isolated areas of the U.S. can certainly appreciate this problem.

6. You can tell others how you do things. Some of you have been towing so long that you consider many aspects of towing to be completely un-newsworthy. But think about it - how much of this "traditional knowledge" has actually appeared in print? Very little! In fact, it was the absence of such "traditional" information that prompted the development of skyting in the first place. Towing practices and techniques are simply not discussed in the normal hang gliding literature. Let's use the SKYTING newsletter now to document some of the history and lessons of conventional towing before they are lost for all time. I am not the only person who would like to have more detailed information about such things as Yarnall release systems, two point bridle systems, power winches, tension reels, water towing, etc. You can tell from back issues of SKYTING that several readers are re-inventing devices others have already perfected.

7. You can let others know where to get various components, I can supply those items needed for the skyting system which I, personally, use, but where can one obtain a control bar cable release system, a power winch, a tension reel, floats, and other conventional towing equipment and components? Even if such items are not suitable for skyting as manufactured, they may be adapted to meet skyting needs.

8. And, finally, you can tell others the truth about skyting. There are a lot of people who are simply misinformed. For example, I have heard that "There is a new towing system on the market which makes winches obsolete!" You can help correct such misconceptions by speaking up when you hear them and by writing letters or articles to other hang gliding publications. Remember, you who read this newsletter are the real "experts" on skyting, and the future of skyting is really in your hands.
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1983/01-03

A MODIFIED BRIDLE FOR EARLY KEEL LINE RELEASE

by Peter Adams

A phone conversation Don had with Tom Pendergraft about the upper connection on the bridle releasing prematurely let to some discussion and experimenting by Tom and me. These are some of my conclusions.

Tom has been recommending to people using his winch to release with tension still on the line, because they found releases on a slack line allowed the release unit to fall on and tangle the control bar, the front wires, or the pilot's head, neck and helmet. We've had the auto-release line fall on one side of the pilot's head while the main line fell on the other side so that the bridle was around the pilot's neck. We've also had the same thing happen while releasing under tension. That's a real thrill, sort of like being lynched in reverse, rope burns and all. Another annoying thing that happens when releasing under tension is that the release unit often hits your helmet as it passes by at high speed. I think the solution to these problems is to release the upper connection early.

A simple modification of the bridle as shown in the diagram allows the pilot to have control of the top release without changing the functioning of the bridle from its original configuration.

Moving the auto-release line back to the second slip-ring puts it within reach of the pilot. A quick tug on the line releases the upper connector whenever the pilot desires.

The bridle applies tow tension to the aircraft proportionate to the mass involved and to some extent relative to the drag. Releasing the top line at low angles of tow would result in a strong tendency of the nose to pitch up, probably resulting in a stall or even a spin about a horizontal axis (a snap roll? Sounds like fun, huh?) Based upon a little experience and some guess work I would say about a 45 degree tow angle is a good place to release, i.e. the tow vehicle or winch is 45 degrees below the horizon relative to the pilot. At this angle there is still some pitch up tendency, but it is easily controlled. In fact, there is some pitch up (slight) even at the "peaked-out" tow angles of 60 degrees. Releasing at tow angles lower than 45 degrees causes too much pitch up.

An added benefit of releasing the top line is that control is increased while flying on the lower attachment point with less yaw and even more roll control. One of the negative factors is that all of the tow force is concentrated through your harness. I always like to release on a slack line because the release unit being snatched out of may hand at up to 200 lb. of tension always makes me wonder if it may take one of my fingers with it. Since the entire bridle is below the pilot and glider, there is no tendency for the bridle to tangle.

Something I would like to see developed for the Hewett Bridle is a way to release the lower attachment without having to remove the hands from the control bar. I know this has been discussed before, but I've seen several situations where it would have been useful. All these situations have occurred at launch: wingtip, wire or control bars caught in brush or weeds causing severe yaw/roll; pilot stumbling and falling before kite is flying; pilot not hooked in or harness tangled, not on properly, dropped stirrup, etc.; missed signal causing pilot to be launched before he was ready. Also I have launched into sinking air or light and variable air that turned downwind as I launched. I know that the observer in the tow vehicle or the winch operator is supposed to cut tension in those situations, but a winch operator is up to 4000 ft. away and an observer in towing can be up to 2000 ft. away and they have only a vague idea of what is happening at launch and may not react in time. In critical situations close to the ground, a pilot shouldn't be faced with a choice between taking his hands off the control bar to release or continueing to fly the glider. If anybody has any ideas about this I would like to hear them.
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Fig. 1. Original configuration.
UPPER RELEASE
AUTO-RELEASE LINE
LOWER RELEASE
LEADER
SLIP RING
SLIP RING
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Fig. 2. Modified bridle. (Do not change length of auto-release line.)
UPPER RELEASE
AUTO-RELEASE LINE
LOWER RELEASE
LEADER
SLIP RING
SLIP RING
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1983/01-04

TOWARD A BETTER RELEASE

by Henry Wise

Towing here in Houston is becoming popular and with it are coming new ideas for improving the release method and mechanism. We have reassigned the release order on the Hewett bridle for the sake of safety. The upper release is now thrown first and the lower one releases automatically. The reason is really simple. If you throw the bottom release and the top one fails to open, you will no longer be pulling through the center of gravity. The kite will nose down (but not radically) and it is felt that the danger of a lockout may exist until the upper release is removed. On the other hand, if the upper release is thrown first, and the lower one fails to open, you are still pulling essentially through the center of gravity. Control of the kite in this configuration will not change significantly. As a matter of fact, one person tows only with the body release.

The upper release mechanism which is in current use in Houston is a typical tow release. It replaces the metal O-ring on the keel, and that O-ring replaces the old release which is on the bridle. The release is activated by a motorcycle brake handle which is mounted on the control bar. Pressing the motorcycle grip causes the release to literally spit the O-ring out.

The lower release is an automatic release of a new kind. I call it a two ring release, and it is similar in design to the three ring releases used in parachuting (see figures). This type of release has several advantages over the horse bridle releases that Donnell has been supplying. Most important of these is that the release pin is easily removed even under high tension. The release will not break when dropped from a great height without a drag chute, dirt won't effect the release function, the materials are extremely cheap and easy to find, and it is easy to make.

All you need are three metal O-rings (A, B, and C), two pieces of rope (A and B), and a release pin. The only size requirements are that ring A must b able to easily pass through ring B, and rope B must be shorter than rope A.

I use a two inch ring for ring B and a 1.5 inch ring for rings A and C. This is because I prefer to use one of Donnell's belts rather than sew a ring onto my harness. There are other people here who have rings sewn on and so they have reduced the ring sizes to one inch and 1/2 inch. Ring size is really a personal choice.

I also make rope A out of nylon rope (the same size as that used in the bridle) and rope B out of weak link. My feeling is that the extra weak link provides an additional margin of safety, although it should never break due to the stress of towing. Most of the stress on the release occurs on Rope A and rings A and C. Rope B will wear out eventually, due to abraision from the release pin, but I have lots of weak link material.

My original release pin was a 16 penny nail. It worked fine, but it would occasionally fall out by itself. My current release pin has enough tension by itself to prevent this.

To set the release, you simply slip ring A through ring B, then slip rope B through ring A. Rope B is held in place by looping it back upon itself and inserting the release pin as shown in the diagram. It's so simple on eight year old could do it, so you'd all better go out and find one!

There are only three critical points. First of all, when everything is set up properly, ring A should make a 30 degree to 45 degree angle to the rest of the release. The reason is that the higher the angle a ring makes to the rest of the release (up to a 45 degree angle), the less pressure there will be on rope B, and therefore the easier it will be to remove the release pin under pressure. If rope B is too short, then you will be towing on rope B and release will be near impossible under stress. The idea is to pull where rope A and ring A meet.

Secondly, make sure that the release pin is as close to ring A as possible, with rope B pulled tightly against the release pin. If this isn't done, the release pin could twist into the wrong position and get hung up.

Thirdly, be sure that the auto-release rope is located at the very end of the last loop on the release pin and that rope B sits at the very end of the first loop. If both ropes sit in the same loop, there is a real danger of pulling only the auto-release rope of and leaving everything else intact.

All of these materials, except for the release pin, can be found in your local hardware store. The release pin can be found at any hang glider or sailboat shop. Be sure that your newly made release is working properly by testing it prior to actual use by releasing it under stress. Roughly 100 lbs should be sufficient since that's when the weak link will break. It's also feasible to use this release for both upper and lower releases on the bridle.

I've been fiddling with variations of this release for several months now and feel that this is the simplest, cheapest, and easiest to build of the bunch. Try it, you'll like it!
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2 - RING RELEASE
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Fig. 1. Expanded view of components.
RING B
PILOT'S BODY RING
RING A
ROPE A
ROPE B
RING C
BRIDLE
RELEASE PIN
AUTO-RELEASE LINE
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Fig. 2. Side view of assembly.
RING B
RING A
ROPE A
ROPE B
RING C
BRIDLE
RELEASE PIN
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Fig. 3. Top view of assembly.
RING B
RING A
ROPE A
ROPE B
RING C
RELEASE PIN
AUTO-RELEASE LINE
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Fig. 4. Top view of assembly.
RELEASE PIN
ROPE B
AUTO-RELEASE LINE
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1983/01-05

SKYTING IN GERMANY

Dear Donnell,

Thanks very much for your letter and SKYTING NO. 5 & 6.

I had my first skyting flight on Saturday, 6th November. The weather was beautiful, clear sky, about +8 to +10 degrees C. Wind at 3000 ft: 130 degrees at 10 knots. Our little airstrip, (800 m long) is situated between a small village on one end and an 80 m hill (not flyable) on the other. Local conditions were: cross-wind between 45 degrees to 60 degrees and 2 to 5 knots.

After long discussions about your recommendations, I decided to pass the bridle line under the A-frame base. There was no problem in ground handling my Mega II. Nevertheless, my first take-off was aborted because just as the line became tight, a gust of wind lifted one wing and the observer free-spun the reel and stopped the vehicle.

My second start was without any problems. It took me about 50 m climbing to stop the over-maneuvering. The next 50 m of climb were beautiful, but then the weak link broke because of speed change of the vehicle.

The reel was stopped for just a few seconds and the breaking loose force on the brake was above 100 kg. The back-snapping line made the top latch release first, but this presented no problem. After releasing the body line, I checked my altitude: 100 m (328 ft). In the second flight we used up all the available towing distance and with less wind I gained 200 m (about 600 ft). This time not over-reacting, but concentrating on speed and optimal angle of attack.

I enjoyed this flight very much, since it proved to me that skyting is everything I hoped for. For this reason, I had no hesitation about letting my friend Gunter Schorberl fly his Demon. Gunter is a very experienced pilot. We tried our various systems together.

The first start was perfect, but Gunter over-reacted the first 100 m. He released at about 120 m (400 ft). On his second flight he gained 150 m (500 ft). After those 4 flights we had to stop because it was getting dark. (There was a lot of talk and evaluation done between flights, and a lot more after).

Today (9 Nov. 82) I had to work, poor me, but came out straight after and managed another few flawless flights before darkness. Our harness will have to be altered as it is not very convenient to tow with a hip-strap because of the position of our parachutes.

At the moment we are using a simple breaking device comprised of:

Reel with 1100 m (3600 ft) sling-type break, spring-loaded mechanism to hold the pre-set break force which is set at 80 kg.

Tow-line is KEFLAR ((Kevlar)) 3 mm diameter.

We chose KEFLAR because of its low flexibility ((stretch)). Previously we used a high flex line, but this led to very dangerous oscilating problems expecially in combination with the three-point bridle system.

There is still a lot to be done to perfect our towing system, but now with Skyting on the pilot end, it is a lot safer to experiment with the winch or reel. We have got all winter in unpeturbed air to gain experience, get the set-up straightened out and be ready for the thermals in Spring and go crosscountry.

Looking forward to hearing from you again sometime.

Peter Roth
Neu-Isenburg, Germany
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1983/01-06

ANSWERS TO SOME OF LAST MONTH'S QUESTIONS

(See SKYTING NO. 8, "Problems with the Skyting Release System.")

Dear Donnell,

I got your letter yesterday and read all the skyting newsletters you sent. It was all very interesting and it finally answered a question I've wondered about ever since I heard of skyting. I read your original article on skyting in Hang Gliding when it first came out and since I was already towing conventionally at the time, I was interested. But then no more articles followed. I finally decided that you must have concluded that skyting wasn't all it was cracked up to be and decided not to finish the series. It simply astounds me that the articles were stopped by the USHGA because of safety considerations! The USHGA will be getting a letter from me about this in the near future because I feel that Danny Cudney would probably be alive today had the series been completed as scheduled. But enough of this, on to the news and answers to your questions.

I learned about skyting from several sources, Whole Air magazine and two local pilots: Tom Pendergraft and Peter Adams. All of my experiences with the skyting system has been with Tom's Yarnall winch. I believe Tom has talked to you about our methods but if not, I'll fill you in. The winch has about 3000 ft of line and depending on wind direction we can usually use 2000-3000 feet. We generally tow to altitudes of 600-900 feet over land. I expect that we can get higher than this but lately we seem to be towing in almost no wind. We don't use a weak link with the winch system. I have also had a chance to watch Peter demonstrate the car tow system and his setup is identical to what you describe in the newsletter.

In answer to your question about why none of the pilots was ever hit on the head while towing conventionally: the reason is because we were using a Yarnall bridle. A Yarnall bridle attaches to the three corners of the control bar and remains attached throughout the flight. A release is mounted at the apex of the bridle lines so that after release the bridle and the release mechanism hang down below the glider.

It turns out that the reason we release the skyting bridle under tension is because of the instances where the upper bridle line wrapped around the control bar if released with no tension.

As it turns out since I last wrote to you, I had a chance to experiment with the system some more and have worked almost all my problems out. The solution was very simple, I attached a piece of rope at the glider CG with a "D" ring at the other end of the rope. The rope was about 15 inches longer than the distance from control bar to keel. That length is not magical, it just happened to be the length of the top bridle line from my old Yarnall bridle. The important part was that it was long enough to place the skyting bridle top line in front of, and below the pilot. This solved many problems: there is no possibility of being hit by the bridle, being choked by it, or tangling around the glider. Also, moving the glider attachment point back to the glider's CG greatly reduced the yawing problems that I had previously. I was able to exercise control over the glider during the tow without inducing yaw oscillations. Previous to this, the only way I could stop the oscillations was to lock my arms so that my body remained as stationary as possible and let the glider damp the oscillations.

This may have had an added benefit: I was able to tow to a greater height than any other pilot present. Since only two other pilots were flying comparable performing gliders, at lower wing loading than I was, the results are probably meaningless.

This method of attachment has one other feature to recommend it. Should the top release fail to release, it is easily reachable by the pilot. the only disadvantage is the length of rope dangling from the keel. In practice this has proved to be of little consequence. The only problem with it that I can see, is that on landing, the pilot could trip on it. Because of the length of the rope, the pilot almost has to trip over the control bar in order to reach the rope.

Steve Goldman
Gary, NC
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1983/01-07

HOUSTON UPDATE

Dear Donnell,

Enclosed is the article on the new release. I hope you'll try it and let me know what you think. (See this issue of SKYTING: Toward a Better Release.) Here in Houston we're getting our winch act together. We've towed as high as 1000 feet with it so far. Everyone here is looking forward to spring. I think we may finally see a 100+ mile flight here next spring. Anticipation is running very high.

A few notes on our progress. A week ago last Sunday (11/21/82) we had a 90 degree cross wind blowing 0 mph at first and later picking up to 5-8 mph. One flyer, who likes to tow only on the body and feels that weak links aren't necessary, had a takeoff in which the winch got hung up and wouldn't play out line. The weak link broke and he landed safely. When we got to him we found him cursing the weak link and vowing never to use one again. However, he changed his tune when he found out why it broke. Now he's a firm believer in weak links. If anyone knows anyone who dislikes weak links, you might repeat this story to them. It only takes one time like this to change a person's mind. Accidents do happen, even to experienced pilots.

Also, cross-wind take-offs by towing are a little harder than off a hill. On the same day, after the cross-wind had gotten stronger, the same pilot got turned on take-off and crunched his Harrier. A broken down tube resulted. He still doesn't believe in wheels!

Bob Fisher has a good suggestion for winch tows. Start towing at about 10 lbs pressure. The pilot just stands there while you drive off. The 10 lbs of pressure keeps the drum from having any tendancy to backlash. Once normal towing speed is reached, the observer bleeds in the rest of the pressure (up to the usual towing force) over a 2-3 second interval. This is not a pop start since the pressure is bled in slowly, but it does cause a very smooth and rapid take off. Two to three steps in no wind conditions are typical. Since the vehicle is already at full speed when take-off commences, there are no problems with the vehicle shifting gears during take off. We are currently trying to modify our winch so the pressure can be bled in gradually. Bob tells us that this procedure is common in England. The take-off looks like the pilot gets jerked off the ground, to the casual observer, but it's really quite smooth.

Say, Don, after we get everything worked out with the winch, how about coming up this way this Spring or Summer. I'm sure we can get you higher than your usual 500 feet! You may even catch a thermal in your old new machine!

Henry Wise.
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1983/01-08

KANSAS TOWING

Dear Donnell,

Hello, from the flatlands of Kansas. I received and read SKYTING No. 1 in early September and though it was great! I had done some experimenting with one attachment point (keel) but it didn't feel right or safe so I quit, thinking "someone will come up with something better". I believe you've made a big step in the right direction.

I also have a homebuilt monopole trike which I designed and built and I think there's an interesting comparison between the trike concept and the skyting concept.

Anyway, I can now afford some of your equipment, back issues #2 to current, and a subscription.

Jule Lorenzen
Galva, KS
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1983/01-09

TOWING IN MASSACHUSETTS

Dear Donnell,

Enclosed is $2.00 for another copy of your SKYTING NO. 1. I sold mine to the people of Aeolus Flight School in Groton, Mass. I was up there last week on vacation and wanted to let people up there know that there's a better towing method available. There appears to be one person there (I never met him.) who is towing using a 3 point bridle with a Yarnall-type release. He's using the same release mechanism as you and claims it works well. His system is set up with two sets of pulleys so that the tow rope is free to move up and down and sideways. I've not seen the actual bridle, but the definitely are not pulling off anything but the glider.

The man I spoke with, Van, was very impressed with your system. I had taken mine with me. He says he'll make one and try it. Van claims it's a much simpler bridle than what they are currently using. He also has your address and you should be getting a subscription from him soon.

Van also invites everyone to stop by the shop and wants everyone to know that his is the last flight school in the country to use standard kites to train with! Donnell, I bet you thought you were the last! By the way, Aeolus is pronounced e-o-lus not A-o-lus. Seems everyone here in Houston has been mispronouncing it!

Henry Wise
Houston, TX
*
INTEREST IN AIR-TO-AIR TOWING
*
1983/01-10

Dear Donnell,

Would you please send me all the info you your SKYTING tow system. I would also like the name and mailing addresses of anyone that has already received this info so I can communicate with them to see how or if they are using it. I live in Mich. and we have no flying 9 months of the year. And from all I have read, SKYTING may be the safest way to fly under tow. I say tow but I am more interested in air-to-air towing (tuging?) of flexwing gliders and I hope (pray) that skyting will make this possible. I would appreciate your thoughts on air-to-air towing with the skyting bridle. I have enclosed $2.00 plus a number of stamped self addressed envelopes and would appreciate you sending along any up dates on skyting especially air-to-air. In Nov./Dec. WHOLE AIR Tom P. going from 5 to 10 mph (high wind?) towing to wanting to skyte in "thermal action" says there must be a dramatic difference in towing and skyting, and has me very excited.

L.P. Flick
Flint, Mich.
*
1983/01-11

Dear L.P.

Thank you for your interest in skyting. Here is the information you requested.

I have not included the names and addresses of those who have tried skyting because there are so many. If you will look in the back issues of SKYTING, you will find the names of many of these individuals. Let me know who you want to communicate with, and I will try to give you their addresses.

You are not the only one who has expressed an interest in air-to-air towing (tuging), but as of this date, no one has reported to me their experiences on this subject. Skyting No. 3 discusses my opinions on this topic, primarily from the theoretical point of view. In essence, I believe that there is no reason that "tuging" cannot be accomplished safely by using a skyting system. In fact, I would never attempt ultralight towing with anything except the skyting bridle. (Or possibly the Brooks Bridle. See Skyting No. 2.)

After you have read the back issues of SKYTING, let's discuss this matter further. I am confident that with only a little development work, the skyting system can be modified to provide a truly safe "tuging" system.

Donnell
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