If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
I like all these points and I suspect that because of the short time
required in a winch launch, and the faster acceleration, and the fact that you are in a position to land on the runway that you are using at all times, the winch launch would be safer, but I still see no statistics! Come on folks, someone surly has crunched the numbers. Training is crucial in both, but what I'm looking for is numbers, I have plenty of opinions myself. Boggs "Bill Daniels" wrote in message k.net... "Gary Boggs" wrote in message ... Someone must have already compared the safety of these tow launch methods. What do the statistics show is the safer method of launch? Aero tow seems to involve more inherent dangers to me. For one thing, there is just more time for things to go wrong. What could be more dangerous than to tie tow airplanes together and try to fly? Gary Boggs I have done a whole lot of both and, given a choice, I'll take winch launch. Yes, things happen fast on a winch launch but then the launch is over in 30-40 seconds so the risk exposure is short - with air tow, you are at risk a least ten times as long. Air tow in turbulent air is fatiguing - you will never get tired in a 35 second winch launch. If you don't like the way a winch launch is going, release and land. You can do that with a winch launch because you should always be in a position to land back on the runway - I can't say that is always true with air tow. Air tow is formation flying - involving two extremely mis-matched aircraft - with a rope tying them together. This requires highly developed flying skills to do safely. We teach this to pre-solo students. (I wonder how we get away with it.) Winch launch can easily be taught to pre-solo pilots since it is a simple, repetitive task. Air tow has two aircraft at risk and at least two pilots - winch launch has only one aircraft at risk. Winch launch accelerates the glider far faster than air tow so dropping a wing due to insufficient aileron control is unlikely. (Of course, you can still drop a wing due to incompetence with unhappy results.) In both cases, the training of the pilots and launch crews have a lot to due with overall safety. There is ample opportunity for either to come to a bad end. With equally good training, I think winch launch is safer. But, lets face it - winch launch LOOKS scary to a pilot trained that a steep nose-up attitude near the ground is dangerous. It isn't dangerous but it sure looks that way. Bill Daniels |
#12
|
|||
|
|||
"Gary Boggs" wrote in message ... I like all these points and I suspect that because of the short time required in a winch launch, and the faster acceleration, and the fact that you are in a position to land on the runway that you are using at all times, the winch launch would be safer, but I still see no statistics! Come on folks, someone surly has crunched the numbers. Training is crucial in both, but what I'm looking for is numbers, I have plenty of opinions myself. Boggs OK, the BGA accident database is available on the web. The database is searchable for flights that began with a winch launch. Note, however, that most of the accidents in this section do not relate directly to winch launch. I think that there were only three or four accidents over a ten year period that actually happened during the winch launch. The rest were accidents that happened later in a flight that began with a winch launch. It seems to me that if winch launch accident data is hard to come by, that in itself is good news. If accidents happened frequently, there would be lots of hard data. Bill Daniels |
#13
|
|||
|
|||
Gary,
I suspect you are considering winch launching for your club and I would think the biggest problem would be in getting club members, "Up to Speed" on winch operations. In way of illustrating my point, allow me to tell a little story about a local soaring operation that is no longer in business. This outfit advertised, get your "Aero-Tow Only" restriction, removed from your glider licence. Come to XXX Soaring and we will check you out in about an hour, or so. This outfit had a 2-33 with only a nose tow hook (mistake no. 1) They didn't use radios (mistake no. 2) The flight examiner weighed a good 300 lb. + your average student at 200 lb. = 500 lb's in the 2-33 (mistake no. 3) I was going to take the course, but had to wait for the student in front of me to get his check-out. The signal for "Start the launch" was, level the wings and flash the lights in the car located near the right wing tip. It went something like this: 1. Level the wings & flash the lights------------Glider rolled about 10 feet and stopped. winch operator stalled the winch. 2. Level the wings & flash the lights---------- Cable went, but glider didn't move. In the last attempt, wheel had rolled over cable and caused a reverse release. 3.Level the wings & flash the lights---------------Glider went about 100 feet and stopped. Cable had "Kinked" in previous 2 attempts and then broke at a kink. -------------30 minute delay while Nico-Press & sleves are found and cable is spliced. With 3 attempts and no success, student is having second thoughts and opens canopy and starts to climb out. Instructor tells him, everything will be fine, this time, Get back in here. 4. Level the wings & flash the lights------------ Glider takes off, to the wild applause of all those assembled. Glider only gets 400 feet due to nose tow hook location. Glider makes a 90 right and a 180 left, lands and rolls right up to the starting point. Attempts 5, 6 & 7 come off without a hitch and the Flight Examiner is called out (300 lbs) Level the wings & flash the lights-------------- Glider takes off, but only gets 300 feet, makes a modified 90/180 and plunks it down hard, way down the runway. I took this opportunity to silently disappear and my licence still reads, Aero-Tow Only. JJ Sinclair |
#14
|
|||
|
|||
|
#15
|
|||
|
|||
Bill Daniels writes:
If you don't like the way a winch launch is going, release and land. You can do that with a winch launch because you should always be in a position to land back on the runway - I can't say that is always true with air tow. This brings up a point I left out of my original post. The SITE must be suitable for winch launching. If the site has a short runway, or obstructions, then the option to release and land straight ahead may be limited. Of course this applies to aerotow as well. Winch launch accelerates the glider far faster than air tow so dropping a wing due to insufficient aileron control is unlikely. (Of course, you can still drop a wing due to incompetence with unhappy results.) If the winch operator does not apply adequate power for rotation and climb early in the launch, the window of opportunity to abort safely closes quickly and leaves unsuitable options. In both cases, the training of the pilots and launch crews have a lot to due with overall safety. There is ample opportunity for either to come to a bad end. With equally good training, I think winch launch is safer. I wholeheartedly agree that training, and practice, are of great importance. I had a winch launch accident early this year in which training played a large part. Also reaction time, and the limited suitability of the site for winch launching. I will give a brief description of the accident: I did not brief the winch driver on my launch requirements (mistake 1), my glider had the highest wingloading of any there that day. The initial acceleration from a stop was weak enough in comparison to all my previous training on this winch to make the hair on the back of my neck stand up. I had enough room to wait for more power (mistake 2) but was too low and slow to wag wings. I briefly pulled back on the stick to see if there was any tension on the cable, maybe the winch had redlined in a lower gear (the winch in question has known issues, mistake 3). I felt the tension completely go away, pulled the release and pushed the nose over. I was not aggressive with the push over (mistake 4), but altitude was only 50-75 feet and the glider was just above stall, so not enough room to gain speed, no room to land straight ahead, and insufficient altitude to complete a turn to the right for a landing on the abort runway. I dragged the right wing and ground looped, breaking the tail boom of my glider, and narrowly missed a Toyota truck that was parked in an unsafe area. During debrief, I found out that the winch driver saw the retrieve chute balloon immediately and thought I released so chopped the winch power. Chute blossoming was common that day on previous launches due to improper chute rigging (mistake 5) and this was probably exaggerated by the lack of full power during the initial part of the launch. The site has about 1000 feet of usable straight ahead runway, but it is downhill from glider to winch, and a portion is steep enough so as to be impossible to walk uphill if the dirt is wet. The abort runway is at a right angle to the launch runway, undulates in elevation 30-40 feet, and has a narrow spot about 60 feet wide bordered by trees and bushes. The dimensions of the site are such that there is a point in the launch when you may be too high to land straight ahead, too low to continue into the ridge lift, and too low to make the landable portion of the abort runway. The situation is worse for higher wingloading gliders (I fly an ASW20) than are typically flown at this site. Some of you may have guessed the site by now, it is Torrey Pines, California. Having had this experience, I would fly there again, but only after addressing the training and briefing issues mentioned. The configuration of this site requires extra special attention to launch procedures, but the satisfaction of flying at such a unique and historic location is well worth it. - Mark Navarre ASW-20 OD California, USA - |
#16
|
|||
|
|||
|
#17
|
|||
|
|||
Anyone who is seriously interested in ground launches should read and
understand Derek Piggott's great book "Ground Launches". Thanks, Derek! BJ Gary Boggs wrote: Someone must have already compared the safety of these tow launch methods. What do the statistics show is the safer method of launch? Aero tow seems to involve more inherent dangers to me. For one thing, there is just more time for things to go wrong. What could be more dangerous than to tie tow airplanes together and try to fly? Gary Boggs |
#18
|
|||
|
|||
Try tying a glider to a truck to fly.
Gary Boggs wrote: What could be more dangerous than to tie two airplanes together and try to fly? Gary Boggs -- Peter D. Brown http://home.gci.net/~pdb/ http://groups.yahoo.com/group/akmtnsoaring/ |
#19
|
|||
|
|||
On Sat, 25 Oct 2003 12:43:35 -0700, "Gary Boggs"
wrote: Someone must have already compared the safety of these tow launch methods. What do the statistics show is the safer method of launch? Aero tow seems to involve more inherent dangers to me. For one thing, there is just more time for things to go wrong. What could be more dangerous than to tie tow airplanes together and try to fly? Gary Boggs I've only done about two winch launches but have done several hundred car tows and driven several hundred also. Ground launches involve lots of wire, rope etc. It is probably a good observation that the more rope you have the more trouble you can get into! With one exception below. I've had the glider run over the wire and tangle in the wheel well. Not good as you now cannot release and depend on the tow driver.. Pilot reactions to a low altitude winch launch failure are utterly critical. I suspect we've killed dozens if not hundreds over the years this way around the world. You may need more than one launch to get away(rare with aerotow). This increases your launch risk exposure. Someone mentioned the stresses in the wire and the glider. Both are much lower in properly executed arotow. Aero tow may have a higher exposure to an off airport landing in unsuitable terrain but the failures seem to be much more rare than winch wire breaks. If you don't use toy towplanes(less than 180HP) then any place suitable for winching probably gives you the opportunity to do a 180 or land straight ahead from an aerotow. If you want gliding to be popular aerotow involves less running around on the ground per flight hour. Flying towplanes is more fun than driving a winch or tow car.(Allegedly - I last sat in a towplane in 1971 writing down CHT's for the cooling test for 4 tows in a row and haven't felt motivated to get into a towplane since despite the aquisition of a PPL 9 years ago) Aerotowing danger can be reduced by using a longer rope. One of the local clubs around here tried it and liked it so much the towpilots won't fly with short ropes. The long rope gives everyone more time to handle upsets. I suspect the rise of the towplane upset accident coincided with using shorter ropes. Mike Borgelt |
#20
|
|||
|
|||
"JJ Sinclair" wrote in message ... Gary, I suspect you are considering winch launching for your club and I would think the biggest problem would be in getting club members, "Up to Speed" on winch operations. In way of illustrating my point, allow me to tell a little story about a local soaring operation that is no longer in business. This outfit advertised, get your "Aero-Tow Only" restriction, removed from your glider licence. Come to XXX Soaring and we will check you out in about an hour, or so. This outfit had a 2-33 with only a nose tow hook (mistake no. 1) They didn't use radios (mistake no. 2) The flight examiner weighed a good 300 lb. + your average student at 200 lb. = 500 lb's in the 2-33 (mistake no. 3) I was going to take the course, but had to wait for the student in front of me to get his check-out. The signal for "Start the launch" was, level the wings and flash the lights in the car located near the right wing tip. It went something like this: 1. Level the wings & flash the lights------------Glider rolled about 10 feet and stopped. winch operator stalled the winch. 2. Level the wings & flash the lights---------- Cable went, but glider didn't move. In the last attempt, wheel had rolled over cable and caused a reverse release. 3.Level the wings & flash the lights---------------Glider went about 100 feet and stopped. Cable had "Kinked" in previous 2 attempts and then broke at a kink. -------------30 minute delay while Nico-Press & sleves are found and cable is spliced. With 3 attempts and no success, student is having second thoughts and opens canopy and starts to climb out. Instructor tells him, everything will be fine, this time, Get back in here. 4. Level the wings & flash the lights------------ Glider takes off, to the wild applause of all those assembled. Glider only gets 400 feet due to nose tow hook location. Glider makes a 90 right and a 180 left, lands and rolls right up to the starting point. Attempts 5, 6 & 7 come off without a hitch and the Flight Examiner is called out (300 lbs) Level the wings & flash the lights-------------- Glider takes off, but only gets 300 feet, makes a modified 90/180 and plunks it down hard, way down the runway. I took this opportunity to silently disappear and my licence still reads, Aero-Tow Only. JJ Sinclair What JJ experienced is, unfortunately, an all too common experience in the USA. A bunch of guys, (it's usually guys) get together and decide to winch launch gliders. ("How hard can it be?" "We can teach ourselves...") They start with poor equipment, a bad site, no experience or training and proceed to scare themselves badly...or worse. They then decide that the problem is winch launch (It doesn't work, low releases, lots of hassles, etc..) and then go back to air tow. I've flown tugs and driven winches - I'll take winches for fun. I've flown lots of air tow and been scared on plenty of occasions. I've flown lots of winch launches and rarely had one go wrong. If anybody wants a winch experienced CFI-G for a week of winch training, email me. I might be available. BTW, How about some of our British and European friends with lots of winch experience jumping in here? Bill Daniels |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Parachute fails to save SR-22 | Capt.Doug | Piloting | 72 | February 10th 05 05:14 AM |
spaceship one | Pianome | Home Built | 169 | June 30th 04 05:47 AM |
The Internet public meeting on National Air Tour Standards begins Feb. 23 at 9 a.m. | Larry Dighera | Piloting | 0 | February 22nd 04 03:58 PM |
USAF = US Amphetamine Fools | RT | Military Aviation | 104 | September 25th 03 03:17 PM |
using winch instead of aerotow | goneill | Soaring | 5 | August 27th 03 02:46 PM |