Towing Aloft
Dennis Pagen and Bill Bryden
Sport Aviation Publications
1998/01
As far as books are concerned, Towing Aloft's predecessor was:
Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974
Very interesting to follow hang gliding culture's stupid, warped, pathetic, decades long efforts to reinvent sailplane towing through the pages of these two publications.
Sailplanes come from the sailplane store ready to be towed from a built in release point. Release can be effected without compromise of control and a weak link on the end of the towline protects the plane from being structurally overloaded. That's about all you really need and hafta know to start having good, clean, safe fun.
Hang gliders have always come from the hang glider store adaptable for towing with - if one considers the harness as part of the aircraft - a fairly easy means of hooking it up for tow. The releases can be engineered with widely varying degrees of difficulty so that separation can be effected without compromise of control - but seldom are - and a weak links on the ends of towlines and/or bridle ends can and should protect the glider from being structurally overloaded - but often aren't configured to do the job.
Until about seven years after publication of Manned Kiting all hang gliders were being hooked up wrong. A two or three point bridle distributed the tow tension to the top and bottom of the control frame. The top connection was OK but the bottom made the glider very dangerously roll unstable and seriously limited pitch control authority.
The gliders themselves sucked. They were crude, divergent, and tended to be underbuilt. Most of the towing conducted was over water (fortunately) behind powerful water ski boats without controlled or even well moderated tension. If EVER a situation was screaming for weak links this was it.
But in the entire freaking book there is ABSOLUTELY NO MENTION OF WEAK LINKS - save for a reprint of the FAA FARs covering sailplanes.
This:
and this:"Never take your hands off the bar." - Tom Peghiny
they got right. And even though the bottom hookup was really wrong the hardware was really good. EVERY SINGLE PHOTOGRAPH of contemporary state of the art equipment with requisite detail depicts a lever or two on the basetube at hand position and the releases themselves are all well engineered Schweizer sorta things."The greatest dangers are a rope break or a premature release." - Richard Johnson
I guess there was some real Darwin stuff going on - with the gliders and bridle configurations as deadly as they were people didn't fuck around with factors over which they DID have control and spent the bucks to do them right.
Also, the fact that they were doing the bridle wrong made it easy to do the engineering to do the release for the wrong bridle right. It's when you're pulling off of a swinging squishy pilot with lotsa flexible appendages all over the place that things get to be a pain - mounting and connecting to rigid straight tubing is a no brainer.
So then at the beginning of the Eighties damn near everything changes fast. People figure out that they need to be pulling all, two thirds, or half through the pilot (or near the pilot on his suspension) with anything left over going to or near the hang point and the Comet has made the scene and the gliders are all strong, stable, and certified.
On tow these gliders are still roll unstable but a thousand times less so and a thousand times more otherwise controllable. There's very seldom a big penalty for shitrigged inaccessible releases, the selective pressures are pretty much taken out of the equation, and the hardware DNA starts going to hell. It's the evolutionary equivalent of shooting all the Cheetahs and watching what starts happening to the Thompson's Gazelles after a few generations - 'cept a million times faster.
Throw in three quarter G weak links and a bunch of idiot tow operators and the deleterious mutation rate goes to light speed - if one weak link blows and lets some moron off the hook at just the right time hang gliding culture will ignore the other ninety-nine needless pops which result in broken downtubes and go into overdrive producing Bailey and Wallaby releases.
So now taking your hand off the bar is a non issue and a rope break or premature release is ALWAYS a GOOD thing.
A weak link is the focal point of a safe towing system.
A weak link is a very simple device--typically a loop of line--that is intended to break in the event towline tensions exceed a safe or desired threshold.
PRECISELY ONE HUNDRED AND EIGHTY DEGREES from what hang gliding had right as published almost a quarter century earlier. Total lunacy.Pro Tip: Always thank the tug pilot for intentionally releasing you, even if you feel you could have ridden it out. He should be given a vote of confidence that he made a good decision in the interest of your safety.
Go through Towing Aloft from the front of the front cover to the back of the back cover.
As easy as it is to configure for both hands on the basetube one point aerotow and as brain dead easy as it is to do two point there are but four drawings of a glider with a Wallaby lever at or appearing to be at a usable location and ZERO photos of an AT glider safely configured.
There is a whole slew of photos of release levers on downtubes where we KNOW they became practically and totally inaccessible in oscillation and lockout situations.
There are ZERO drawings and photos of any other hang or para glider configured for both hands on the controls actuation EXCEPT a couple of daguerreotypes of Bills Moyes and Bennett towing standards.
Despite the fact that there were bite controlled throttles used for Soarmasters in the Seventies there is not a SINGLE REFERENCE to a bite controlled release actuator.
There is not a SINGLE REFERENCE in the entire stupid book to a release which allows both hands on the controls for a hang or para glider being advantageous or even desirable.
There is not a SINGLE INDICATION that the authors understand that a configuration that auto releases at high pitch attitudes - like the one that killed two US pilots in 1996 shortly before publication - is the least bit dangerous.
Even after this neither one of these idiots reveals a ghost of an understanding that if you don't have a weak link on THE END OF THE TOWLINE - as the USHGA and FAA regulations clearly state - you NEED weak links on BOTH ends of the bridle(s).I witnessed a tug pilot descend low over trees. His towline hit the trees and caught. His weak link broke but the bridle whipped around the towline and held it fast. The pilot was saved by the fact that the towline broke!
There is not a SINGLE SERIOUS TREATMENT of a weak link as a device which protects a glider - or release - from being overloaded. EVERYTHING in the book regarding weak links is a bunch of totally clueless bullshit strategy to get them as close as possible to normal tension to make the tows as "safe" as possible. Recommended MAXIMUMS are 1.20 for hang glider surface, 1.00 for aero, and 0.75 paraglider.
One ultralight sailplane "pilot" is spoken of favorably for his use of 0.20 - no, that's not a typo, you heard me right - ZERO POINT TWO ZERO. That's a QUARTER of the MINIMUM the FAA ALLOWS for towing in REAL aviation. That's about fifteen percent of what a sailplane manufacturer specifies.
There is not a SINGLE INDICATION OF UNDERSTANDING that a weak link failure under any circumstances can be anything more serious than a minor inconvenience.
And about half a dozen years later after Dennis finds himself in a situation in which his life was seriously endangered by a bent pin release which required diversion of a hand from the task it was performing and very likely would've been terminated if the tug pilot had made a good decision in the interest of his safety, his one point system had auto released, or the focal point of his safe towing system had vaporized we still don't get a renunciation of all the crap he and Bozo Bill had written.