But if A breaks at 225 and B breaks at 412, which would break sooner with less residual affect on the pilot?
1. A 914 Dragonfly without the turbocharger kicked in accelerates a hang glider with about 125 pounds of thrust delivered through the towline to safely in excess of its stall speed for a crisp takeoff.
2. People have no problem at all getting killed at twenty miles per hour.
3. If someone can get killed at twenty miles per hour a millisecond prior to the failure of a 225 pound weak link - and he CAN - he can't get any more killed waiting a millisecond or the length of the runway for the 412 to blow.
4. In a power whack like Davis's:
http://ozreport.com/pub/fingerlakesaccident.shtml- the THIS kind of "accident" in your "I know about this type of accident because it happened to me" I would predict that there would be absolutely no discernible difference whatsoever in the outcome or appearance of that richly deserved little incident whether the weak link had been 150 or 600 pounds.
It's a bit like a squirrel getting run over by an eight year old kid on a bicycle going ten miles per hour or a fully loaded logging truck going seventy. Either way - no more squirrel.
5. YES - *IF* I were being dragged down a strip helpless to release myself I would MUCH prefer to have something between the tug and me which blew at 225 - versus 412 - pounds.
Likewise if I were veering off the highway at night in a drizzle heading towards a tree I'd rather be going twenty miles per hour than sixty. But I can maintain my car and drive at sixty in manners such that the tree scenario is a virtual impossibility.
But if I put a governor on my engine that limits my speed to twenty to attempt to solve the imaginary tree problem I'm sending my probability of getting run over by an actual fully loaded logging truck going seventy through the ceiling.
And if A worked in 100% of the time (personal experience) in normal towing situations, why should B even be considered?
1. 'Cause THIS:
Manned Kiting
The Basic Handbook of Tow Launched Hang Gliding
Daniel F. Poynter
1974
"The greatest dangers are a rope break or a premature release." - Richard Johnson
didn't suddenly stop being true when Donnell published the 1981/10 edition of his Skyting newsletter with the following certifiably insane statement:
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.
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.
http://www.youtube.com/watch?v=bTa6XL16i0Uhttp://www.youtube.com/watch?v=JR_4jKLqrusYou're flying at 272 pounds using a 225 pound weak link. The total asshol*s who control the aerotow operations are putting everyone and his dog up on 130 pound Greenspot (on bridle ends) and those damnable little pieces of s*** make life absolute hell. It's no fun whatsoever doing every single launch with your heart in your throat scared to move the control bar an inch because you're likely to get dumped if you do.
http://www.vimeo.com/17472550(red)
2. It's a breathtakingly bad idea to base standards and recommendations on some arbitrary figure or procedure because something has "worked" for ONE individual on TWO occasions.
A person who - just as he was taught by Matt Taber or Steve Wendt - always does a hang check at back of the ramp so he knows he's hooked in then moves into position, organizes his crew, waits for a good cycle, checks for traffic, says "Clear!", and launches will typically have such an OUTSTANDING record of and experience with success that the idea of verifying that he's hooked in within two seconds of launch seems totally absurd.
3. "I always get my Blood Alcohol Content up to 0.15 before I get behind the wheel because there's good evidence to indicate that a driver who's plastered - and thus relaxed - is much less likely to be seriously injured than the driver and passengers of the other vehicle when the two collide."
Yeah, using a device which takes control out of the pilot's hands may very well mitigate the severity of crashes of several flavors but you can bet the farm that it's gonna CAUSE a lot more crashes in the first place - and some of them are gonna be serious and fatal.
4. You're looking at the issue like "A" and "B" are the only means of addressing your issue. I got news for ya - A and B BOTH SUCK. You keep ignoring C - which really should be A, B, and C.
A - Use a dead-man switch.
B - Use a dead-man switch.
C - Use a dead-man switch.
Your hand moves on or comes off of the basetube and/or the string comes out from between your teeth and you're off tow. That way you can use the weak link for the purpose it has in REAL aviation...
Tost Flugzeuggeratebau
Weak links protect your aircraft against overloading.
...and spare yourself the tedium of the advanced physics and mathematics involved in determining the precise value required to blow you off tow when the s*** hits the fan in a manner such that you need to get off two seconds ago and hold you on tow when the s*** hits the fan in a manner such that you need to stay on for the next five seconds.
5. And maybe you could explain to me why anyone with an IQ up into double digits or better would NOT take advantage of that technology. ("Well, I haven't been killed yet - and neither have any of my friends recently - so what I'm doing now is obviously fine!")
Tad, have you ever been dragged on a blown foot launch with too strong of a weaklink?
1. No. The chances of blowing a foot launch tow are about ten thousand times higher than the chances of blowing a dolly or platform launch so I avoid foot launch tows like the plague.
2. If I were in an environment in which rolling launches were not practical and gonna be doing a lot of foot launches I'd develop an electrical device which blows me off tow by means of a button velcroed to my finger and expect to get a lot more bang for the buck than I would for the cost of my parachute. I prefer having control of situations myself over faith in the good intentions and timely response of a piece of fishing line.
3. Define "too strong of a weaklink" in Gs. When you've centerpunched a thermal or dust devil just coming off the ground and ore standing on your tail and going up like a rocket - a la Eric Aasletten - what weak link is "too strong"?
I have, sideways. It ain't fun.
So why didn't you release?
Some years later when more had been learned and things changed, I messed up again in similar fashion, the .8G weaklink broke and kept me from being dragged as before.
So why didn't you release?
As well, one of our newer pilots on his first day out static towing, had a wimpy, wallowing takeoff from "running into" the line. The observer called for the car to stop, pilot slid in on his belly and the weaklink broke allowing him to stop quickly without the glider doing a ground tumble.
So why didn't he release?
But I guess empiric evidence like this doesn't count for anything in your world.
No, I totally love it. Keep it coming. What it tells me is that ever since the early Eighties when the Hewett approach to towing became all the rage the concept of a hang glider pilot being able to use a RELEASE to abort a dangerous situation has become as alien and unimaginable as using a wheel landing to diminish the likelihood of breaking a downtube or arm or a hook-in check within two seconds of launch to eliminate the possibility of falling out of one's glider.
Now...
Mike Van Kuiken - 2005/10/13
The weak link broke from the tow plane side. The towline was found underneath the wreck, and attached to the glider by the weaklink. The glider basically fell on the towline.
You wanna comment on THAT empirical evidence? Or do the conditions of your USHGA Safety Award preclude you from saying anything negative about understrength weak links?