Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974
"Never take your hands off the bar." - Tom Peghiny
"The greatest dangers are a rope break or a premature release." - Richard Johnson
"A bad flyer won't hurt a pin man but a bad pin man can kill a flyer." - Bill Bennett
Donnell Hewett - 1980/12
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."
A couple weeks ago it dawned on me that there's a HUGE dynamic going on in this third-of-a-century weak link war we've been having in the wake of Donnell Hewett's lunatic reinvention of aviation.
Donnell's approach was - and IS...
- Use a magic center of mass bridle so the farther out of line the glider gets the more effective the autocorrection force becomes.
- Don't bother with an expensive constant tension winch system because a nylon parachute shroud towline with a tension gauge will accomplish pretty much the same thing and if the tension gauge is reading low and steady the glider COULDN'T POSSIBLY be in any kind of trouble.
- A really light weak link will also keep the glider from getting too far out of whack and ensure that a pop will never be anything more consequential than a mild inconvenience.
- Put somebody on the back of the truck, give him a machete, and tell him to err on the side of caution in fixing whatever's going on back there. (The bad pin man doing the single thing most likely to kill you is now a good pin man doing the single thing most likely to save you.)
- Use whatever cheap hardware store crap you feel like to concoct a release with an actuator anywhere but on the basetube because you've already got such huge safety margins and so much redundancy that it would be absurd to waste the time, effort, and expense to pursue the matter further.
And hang gliding culture, after a brief period of hesitation, ate this up with a spoon because it was EXACTLY the sort of thing it wanted to hear. Step right up, ladies and gentlemen. Let's get AIRBORNE! No engineering, expensive equipment, tedious preparation, aviation theory, or thinking required. And DO make sure to studiously ignore anything inconsistent with this approach...
Mike Lake - 2011/03/02 01:11:45 UTC
In the early '80s we were given a demo of a fixed line tow system complete with spring gauge, spaghetti bridles, rings, string and chunks of metal at longbow tensions positioned in front of the pilot's face.
The release was some kind of boat shackle that required about same continual tugging to actually release as it does for me to untangle my mobile phone charger.
After release the line had to unthread itself from various rings before the glider was actually free from a rather pathetic tow launch.
This was utter, utter crap, the whole setup and we (rather unkindly) laughed.
...because Skyting Theory predicts that it'll kill you in a heartbeat.
But a lot of this evolved or re-evolved without / in spite of Hewett's best efforts... constant tension payout winches, Spectra (zero stretch) towlines, one and two point bridles, two stage release, launch platforms and dollies, ultralight tugs...
Areas of stagnation and reverse evolution...
- Outside of Russia with their bite controlled one point aero releases and whatever dent Joe Street has made with his two point aeros there's zilch in the way of that can be blown safely/survivably - or at all - in most emergency situations, particularly lockouts. And most of the cable, velcro, bent pin crap used for aero is actually considerably worse than Hewett's second generation stuff - at least he ensured that they'd handle his magic one G weak link / stall and lockout preventer limit.
- The vast majority of towing is aero, virtually all aero is limited to Rooney Links, and Rooney Links hold the vast majority of gliders to well under the one G that Hewett was so happy with and insistent upon. And a huge number of gliders - mine fer instance - are held below the 0.8 G minimum. And it's virtual heresy to suggest that a weak link should scale with either flying weight or glider capacity.
TUGS, on the other hand, are EXREMELY well protected:
- excellent, built-in, no control compromise releases
- illegally light weak links on both ends of the towline
- tug weak link commonly lighter than the glider weak link
- illegally light tow mast breakaway just in case a glider or two figures that they're being scammed and fucked over and tries to reform anything
http://ozreport.com/12.081
Weaklinks - the HGFA rules
Davis Straub - 2008/04/22 14:47:00 UTC
Pilots must use weaklinks provided by the meet organizers and in a manner approved by the meet organizers. All weaklinks will be checked and use of inappropriate weaklinks will require the pilot to go to the end of the launch line to change the weaklink.
Weaklinks will consist of a single loop of Cortland 130 lb Greenspot braided Dacron Tolling line and should be placed at one end of a shoulder bridle.
http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links
Jim Rooney - 2007/07/22 22:30:28 UTC
No, I'm not being nice. No, I do not feel the need to be nice. You're trying to convince people to be less safe. I don't want to be on the other end of the rope when someone listening to this drivel smashes in.
I've heard it a million times before from comp pilots insisting on towing with even doubled up weaklinks (some want no weaklink). I tell them the same thing I'm telling you... suck it up. You're not the only one on the line. I didn't ask to be a test pilot. I can live with your inconvenience.
http://www.chgpa.org/forums/viewtopic.php?f=2&t=2467
weak links
Jim Rooney - 2007/08/01 13:47:23 UTC
Whatever's going on back there, I can fix it by giving you the rope.
Jim Rooney - 2007/08/01 19:49:30 UTC
It's more of this crappy argument that being on tow is somehow safer than being off tow.
http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec
Jim Rooney - 2013/02/16 05:05:41 UTC
You see, I'm on the other end of that rope.
I want neither a dead pilot on my hands or one trying to kill me.
This is - and, since very early in the game, has been - a war between glider pilots and...
http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
Jim Rooney - 2013/03/05 21:40:02 UTC
You want MORE.
I want you to have less.
This is the fundamental disagreement.
You're afraid of breaking off with a high AOA? Good... tow with a WEAKER weaklink... you won't be able to achieve a high AOA. Problem solved.
I'm sorry that you don't like that the tug pilot has the last word... but tough titties.
Don't like it?
Don't ask me to tow you.
...bad pin men, drivers, tow park operators, meet-heads, clubs, commercial interests, national organizations.
They don't give a flying fuck if you get killed by their crappy training, equipment, towing, negligence. They just wanna do EVERYTHING POSSIBLE to make sure you don't get killed ON TOW. Because if you're killed ON TOW they were supplying the power that killed you and that opens up HUGE responsibility, legal, liability issues for them and everybody up the chain of command.
But if they can cut you loose or your - or the tug's - Rooney Link blows two or three seconds prior to impact...
http://ozreport.com/forum/viewtopic.php?t=31052
Poll on weaklinks
Brad Gryder - 2013/03/06 22:17:31 UTC
In my opinion, because we hang glider pilots are more exposed, have little crash protection, and can land almost anywhere in an emergency, then we would be better served to be near or below the lower end of the suggested weaklink strength spectrum.
Any hang glider pilot who is fearful of having a weak link failure anytime during tow is in need of additional training. He's either towing over areas where he shouldn't be, or he's flying wrong, or both.
I'd rather have my weak link serve a dual function (as both a safety fuse and as an emergency back-up release), than to be so strong that it continues to pull me into the ground should I impact while on tow. A good well-practiced aerotow pilot can manage his line tension and keep it reasonably low, then break the weak link to come off tow if he wishes to do so. When the hang glider pilot breaks a "weak" weak link, the tug pilot just feels a little nudge, and that's it. Nothing scary happens on either end of the line, and both pilots fly away as normal.
...it's because you were a crappy pilot (and ain't around anymore to present an alternate perspective). Or, if necessary, you were a good pilot...
http://ozreport.com/forum/viewtopic.php?t=30971
Zach Marzec
Paul Tjaden - 2013/02/07
Beyond these facts anything else would be pure speculation. I have personally had numerous weak link breaks on tow, both low and high, after hitting turbulence and have never felt in danger of a tumble. I have witnessed countless others have weak link breaks with no serious problems. We train aero tow pilots how to handle this situation and I am certain that Zach had also encountered this situation many times before and knew how to react properly. Apparently, Zach simply hit strong low level turbulence, probably a dust devil that could not be seen due to the lack of dust in Florida, the nose went too high and he tumbled at a very low altitude.
Strong dust devils in Florida definitely do exist even though they are rare. My wife had a near miss when she encountered a severe dusty a couple years ago and I almost lost a brand new $18,000 ATOS VX when it was torn from its tie down and thrown upside down.
I wish I could shed more light on this accident but I am afraid this is all we know and probably will know. Zach was a great guy with an incredible outlook and zest for life. He will be sorely missed.
...who apparently just had some bad luck with an invisible dust devil.
Summary...
The instant WE'RE off the hook EVERYONE ELSE is off the hook.
And that's why we're never gonna be able to fix this problem on any satisfactory scale or higher level. If Hewett hadn't handed us this insanity freedom loving commercial interests would've invented it on their own.
But, hell, let's keep doing the same thing over and over and hope for better results. We're about all we've got.
