...release by biting or opening...
Biting. You bite and cable is pulled - just like squeezing a bicycle brake lever. Normally that would open the throttle / increase power on your engine.
Seems to me hard to manage...
These things have been around since the Seventies when people were using the Soarmaster - the Mosquito's predecessor. They're intended to be and are used the entire time until people run out of gas.
Jim (Scruffy) LeMieux - 1979/02
Mount Clemens, Michigan
I recently witnessed an incident with a motorized glider which I felt should be brought to everyone's attention. The pilot was flying a 215 Alpha with a Soarmaster unit he had slightly modified. Rather than the mouth throttle, he had a deadman's throttle on the control bar U-tube. He would lock the throttle in a wide open position while flying in order to have his hands free. He also had a kill switch which had to be held closed for a second in order to shut down the engine. I warned him of the danger involved, should he have to abort, but he replied, "We don't abort."
After flying all day without incident, one side of the propeller let loose at the hub. The pilot was 100 to 150 feet in the air at the time. If you have ever seen the vibration caused by even a slightly out of balance prop, you can imagine the violent shaking caused by a prop with only one blade. The control bar shook so badly that the pilot could not find the throttle or kill switch. The glider was shaking so violently, he said it felt like he was being electrocuted. Fortunately, he was flying a stable and well built glider and was able to ride it down and land without damage.
The moral of the story is never use a throttle that is locked in position. No matter how uncomfortable the mouth throttle may be, it is the safest way. Also, I recommend the type of kill switch I personally use. It is a snowmobile type that has the base mounted on the control bar and a pin which pulls out to break the connection. The pin is attached to one end of a cord with the other end clipped on your sleeve. This way you need only to jerk your arm in order to kill the engine.
As I have had my flying wires break because of an out of balance prop, and I feel this latest accident could have been caused by the same thing, I can't stress strongly enough how important it is to check the balance of your prop every time you go out to fly.
It seems you also need two hands to fly a powered glider when the power is with rather than in front of you.
But we're only on tow for three or four minutes. And we're only in much danger for the first couple of hundred feet. When I use my Four-String I spit the trigger line out at about two hundred feet so I don't accidentally arm it.
By climbing the top attachement would become more tense instead if it were the case...
Oops. I massively screwed up interpreting what I was looking at and also did the geometry backwards on my mistaken assumptions.
I was trying to download it from Youtube through dialup and it would crash when I tried to watch it through afterwards. I had only been able to see it via cell phone and that wasn't helping things. Had better luck on the computer this morning.
Those guys are using Hewett Bridles. Unbelievable. The Hewett - or Skyting - Bridle is a two point bridle - pilot and keel - which is a pulley system that puts two thirds of the tension on a ring on a bridle between the pilot's hips and the remaining one third up to the glider in front of the hang point. Thirty years now and people still haven't figured out that it doesn't do anything
Is the risk of tumbling...
No, just the opposite. With the bridle pushing up on the basetube there's a tendency for the glider to nose up / stall - but that's usually manageable. But god help you if the bridle catches on something mounted on - or protruding from the ends of - the basetube. There have been several serious/fatal crashes as a consequence of that scenario.
But the original Hewett Bridle was without a doubt the most dangerous device ever deliberately put on an aircraft by someone who wasn't a terrorist. It was released from the pilot end first and - if you were lucky - through Rube Goldberg engineering the top release would be auto triggered and wouldn't smash you in the helmet (btdt) or hands and would clear the glider without tying itself to the basetube and/or flying wires. And several gliders were totaled before they hit the ground when the top connection WASN'T auto triggered.
Those guys have what looks like a really nice winch setup - but they're idiots for not matching it with a really nice Koch two stage at the more important end of the operation.
...or maybe stop all activities
I think that if we do everything right we can eliminate one hundred percent of the risk out of hang gliding - EXCEPT getting tumbled by a rogue thermal or a shear layer, and then we've still got better than a prayer with the parachute.
The Tim Martin fatality at Henson Gap a month ago was a pretty tough one. I'm not at all sure I would have fared any better myself in that situation.
But I've never heard of tow incident that couldn't have been prevented with competence at both ends of the line and good equipment.
As I told you, they use a pulley rather than a ring and expect a zero risk to wrap... I haven't the same feeling at all.
The New South Wales guys are clear here, I'll give them that. There's zero risk of a wrap but the price for that is there's a one hundred percent risk of having to take a hand off the basetube every single time you have to release. Donnell Hewett, Peter Birren, Dennis Pagen, Bill Bryden, and hang gliding culture in general dealt with that risk by defining it not to be a risk.
Doug Hildreth - 1991/06
Pilot with some tow experience was towing on a new glider which was a little small for him. Good launch, but at about fifty feet the glider nosed up, stalled, and the pilot released by letting go of the basetube with right hand. Glider did a wingover to the left and crashed into a field next to the tow road. Amazingly, there were minimal injuries.
Comment: This scenario has been reported numerous times. Obviously, the primary problem is the lack of pilot skill and experience in avoiding low-level, post-launch, nose-high stalls. The emphasis by countless reporters that the pilot lets go of the glider with his right hand to activate the release seems to indicate that we need a better hands-on way to release.
I know, I know, "If they would just do it right. Our current system is really okay." I'm just telling you what's going on in the real world. They are not doing it right and it's up to us to fix the problem. Think about it.
...being towed by 2 point at high altitude as you can see here, put the upper part of the bridle close to the basebar. Hope the bridle never wrap around the basebar or anything on the pilot...
For Greg...
- If the (upper) bridle isn't in contact with anything at the moment of release I can't see that there's really any possibility of it snagging anything.
- If the bridle is close to the basetube and pilot then the glider is - by definition - at a high tow angle and thus high altitude. It's pretty hard to get into a really dangerous situation on tow at altitude.
- With a lot of line out the proximity of the upper bridle to the pilot and glider can't change quickly.
- If the upper bridle DID tie itself to something he can solve that problem with the secondary release (or probably even a hook knife or parachute).
- This is a pretty common form of towing and I've never heard of that problem manifesting itself.
- I think they're keeping him upright and on the downtubes to keep his head away from the bridle when he's topping out.
- If I were to do that tow I'd have the primary release actuator on the basetube, rotate to prone immediately after launch, and either go back upright or probably twist my body while topping out.
- I think I mostly like the way they're doing this (and I don't say something like that about people in hang gliding very often). I think I'd opt for this over a Koch.
- But I also think they can and should be using a cart and starting him with his hand on the basetube and trigger.
I thought 3 rings were better, as pb occured with 3 strings...
- Hang gliding stole the three-ring from skydiving (Bill Booth) in about 1983.
- It was soon modified to a three-STRING because people preferred strings over rings flying back in their faces.
- If they had been really smart they'd have stopped using perlon for bridles and gone with Dacron or other low stretch materials so it wouldn't have mattered.
- As similar as they look the core principles are really quite different. Both are force reduction mechanisms but the rings are a based on a lever system and the strings are based on a pulley system.
- I believe the rings are actually a lot more efficient.
- Note that the third (big) ring is not really part of the mechanism - it's what's released by the mechanism - equivalent/analogous to our tow ring.
- The ONLY real problems with multi-strings were that they were often put together by idiots who built in obvious predictable defects. The Ron Smith I mentioned yesterday was killed (1992/09/10) because the end of the release pin was left exposed where the lanyard could and did hook over it.
- OK, there's another somewhat minor problem with multi-strings. The more strings you add to handle high loads the more you degrade the performance for light loads. Often after topping out at the end of a truck tow there isn't enough tension to blow a three string so you've got to tug it a couple of times to dump the line. One could conceive of a situation in which that could be dangerous but they don't seem to happen in real life in situations in which multi-strings are employed.
- Also... I much prefer barrels because multi-strings burn themselves a little with each use and barrels have excellent performance over a very wide range.
- But for a secondary/emergency release that can handle a lot of load and won't blow inadvertently...
I was talking about towing force not AT.
Do you mean you're not allowed to set winch tension above 1.6 Gs? If so, it seems a bit weird but I can't really see a major problem with that.
they just told me using no wl at all.. (as in paragliding here in France)
This is wacko. It's a million times LESS wacko than one G or under and a big move in the right direction but it's still wacko.
They're risking release overload and glider structural failure for NO reason. Granted, those risks may be microscopic - but there's no reason to take them. Put goddam two G weak links on everything and you're never going to seriously overload anything.
and I remembered not using one when I was towed by a koch.
Don't fly without a weak link. Get a Tost Number Eight / 200 decaNewton weak link and throw it in the bag. Or just put SOMETHING between the towline and the over/under split that goes to your Koch.
It should be enough strong to resist to the jolt at the 1st stage release?
Definitely. You're not going to die if it fails at that point but use something heavy.
Nobody want a blow close to the ground with big angle.
You must be MAD!!! The entire foundation of towing safety since 1981 has been to have a blow close to the ground at a high angle. Just read the Skyting newsletters, Towing Aloft, and the BHPA towing regulations.
I thought the driver was the wl..
The driver is your tension/thrust control regulator. The weak link is YOUR GLIDER's emergency fuse for after all control of the situation - and most hope for survival - was lost five seconds ago. But most tow operators and all (idiot) tug drivers conceive of the weak link as the driver.
shoulders ? you'd like to say hips.
I'm confused here.
When I looked at the photo:
http://hikkaduwa.free.fr/images/M_images/activites/CABANAC/120211/cab3G.jpg
I thought I was looking at aerotow because:
- the guy clipped into the glider has his secondary bridle connected to his harness fairly high and his primary bridle appears to be routed OVER his basetube; and
- the guy holding his keel has a bridle connected high on his shoulders.
But now I'm thinking this is the same operation as the Gregoire video?
Maybe the guy on the keel is going to release at a low tow angle?
If someone is staying at a low tow angle (and aero is ALWAYS at a low tow angle) go to the shoulders and use barrels.
If someone is going from a low to a high tow angle (all surface except platform) use a Koch two stage or a two point with the secondary bridle at the hips. And for secondary releases use whatever works that either doesn't come into contact with the basetube or won't have a problem if it does.
double loop on both ends of the secondary ? you said long bridlelink..
different options?
The Bridle Link is better but - in that application - we're very unlikely ever to see or read about anything in which it will make the difference between a safe tow and a crash.
What is the real advantage of a 2 point (glider+pilot) by towing? prevent "surpilotage" (oversteering?)
- The lower the tow angle the more of an advantage two point towing offers.
- At high tow angles (like platform in which the angle is high and constant) it offers no advantage whatsoever and in fact becomes problematic...
Hope the bridle never wrap around the basebar or anything on the pilot..
...as you just observed.
- At low tow angles two point doesn't prevent overcontrolling - but it does make it a whole lot less likely for people who are new and haven't gotten the feel for one point (which was the big catalyzing factor in the Holly Korzilius crash).
- The main disadvantage to one point towing at low angles is that - despite Davis's contradiction of reality - you're pulled forward more than the glider is so you're farther through the control frame than God and Wills Wing intended during certification. And that means that when you stuff the bar it's not really stuffed.
If you get blasted by a thermal shortly after launch on a payout winch or long static line that's still not a big problem (if the release lanyard isn't on your wrist, your weak link holds, and there's no idiot on the other end trying to help you out) because you can continue climbing indefinitely and ride it out.
Low on aero however...
Dennis Pagen - 2005/01
Soon after lift-off the trike tug and I were hit by the mother of all thermals. Since I was much lighter, I rocketed up well above the tug, while the very experienced tug pilot, Neal Harris, said he was also lifted more than he had ever been in his heavy trike. I pulled in all the way, but could see that I wasn't going to come down unless something changed. I hung on and resisted the tendency to roll to the side with as strong a roll input as I could, given that the bar was at my knees. I didn't want to release, because I was so close to the ground and I knew that the glider would be in a compromised attitude. In addition, there were hangars and trees on the left, which is the way the glider was tending. By the time we gained about sixty feet I could no longer hold the glider centered - I was probably at a 20-degree bank - so I quickly released before the lockout to the side progressed. The glider instantly whipped to the side in a wingover maneuver.
...it's a BIG problem because you're on a short fixed towline, the tow angle is going up fast, and there's another plane down there somewhere on the other end of the line who has a limit on how much misalignment he can take before he starts thinking about his loved ones - or, in a pinch, the wife and kids.
And it's almost certain death if you're towing behind an asshole like this:
Jim Rooney
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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.
And yes, get behind me with a "strong link" and I will not tow you.
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Whatever's going on back there, I can fix it by giving you the rope.
It's more of this crappy argument that being on tow is somehow safer than being off tow.
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which I was for just about all of my aerotowing career.
- The higher the performance the glider the less far forward you'll be pulled but you'll never have as good a safety margin as you would two point.
not to manage 1st stage release?
I can't imagine that that has EVER been anything of a safety issue.
- You're doing it only when you're at a higher tow angle (read: with reasonable altitude).
- There's a wide window for performing the action.
- You're not going to die if you don't do it - the worst you'll suffer is limited climb.
- If an emergency release is required the stage issue is totally irrelevant.
- I've never heard of an incident relating to this issue.
