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#1
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Wing Launch - Can it pull your wings off?
I was sent this link from a UK soaring friend of mine about a death
when the wings came off of a glider during a winch tow. http://www.dailymail.co.uk/news/arti...ll-glider.html Sad story. A few things; - My friend's thought was that the wing pins were left out. Howerver, this was the second flight of the day. Both winch launches. So I would think that the wing pins were installed but the wings failed under a winch load. Which glider was it? Older? Wooden spars? Never having had a winch launch, what happens if you don't release back pressure at the top? Can you pull your wings off? Maybe safeties on the pins were missed and the pins wiggled out on the second flight after staying in for the first. - I was under the impression that the BGA required parachutes for all pilots. Wrong? 1000 ft should have been enough to get out in time but who knows what was happening in the cockpit or if she was 1000 MSL or AGL at the time. Thanks. - John DeRosa |
#2
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Wing Launch - Can it pull your wings off?
On Aug 12, 4:16*pm, ContestID67 wrote:
I was sent this link from a UK soaring friend of mine about a death when the wings came off of a glider during a winch tow.http://www.dailymail.co.uk/news/arti...lunged-death-b... Sad story. *A few things; - My friend's thought was that the wing pins were left out. *Howerver, this was the second flight of the day. *Both winch launches. *So I would think that the wing pins were installed but the wings failed under a winch load. *Which glider was it? *Older? *Wooden spars? Never having had a winch launch, what happens if you don't release back pressure at the top? *Can you pull your wings off? *Maybe safeties on the pins were missed and the pins wiggled out on the second flight after staying in for the first. - I was under the impression that the BGA required parachutes for all pilots. *Wrong? *1000 ft should have been enough to get out in time but who knows what was happening in the cockpit or if she was 1000 MSL or AGL at the time. Thanks. - John DeRosa I suppose if you overload the structure you can rip the wings off anything. No glider is immune from this. |
#3
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Wing Launch - Can it pull your wings off?
On Aug 12, 5:16*pm, ContestID67 wrote:
I was sent this link from a UK soaring friend of mine about a death when the wings came off of a glider during a winch tow.http://www.dailymail.co.uk/news/arti...lunged-death-b... Sad story. *A few things; - My friend's thought was that the wing pins were left out. *Howerver, this was the second flight of the day. *Both winch launches. *So I would think that the wing pins were installed but the wings failed under a winch load. *Which glider was it? *Older? *Wooden spars? Never having had a winch launch, what happens if you don't release back pressure at the top? *Can you pull your wings off? *Maybe safeties on the pins were missed and the pins wiggled out on the second flight after staying in for the first. - I was under the impression that the BGA required parachutes for all pilots. *Wrong? *1000 ft should have been enough to get out in time but who knows what was happening in the cockpit or if she was 1000 MSL or AGL at the time. Thanks. - John DeRosa There was a thread about this recently. The Gist: IF glider is in proper condition AND correct weak link is used THEN- you won't pull the wings off on launch. And- 1000 ft is not much time to asess, open canopy, get out, and open chute. Virtually no chance. FWIW UH |
#4
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Wing Launch - Can it pull your wings off?
On Aug 12, 3:16*pm, ContestID67 wrote:
I was sent this link from a UK soaring friend of mine about a death when the wings came off of a glider during a winch tow.http://www.dailymail.co.uk/news/arti...lunged-death-b... Sad story. *A few things; - My friend's thought was that the wing pins were left out. *Howerver, this was the second flight of the day. *Both winch launches. *So I would think that the wing pins were installed but the wings failed under a winch load. *Which glider was it? *Older? *Wooden spars? Never having had a winch launch, what happens if you don't release back pressure at the top? *Can you pull your wings off? *Maybe safeties on the pins were missed and the pins wiggled out on the second flight after staying in for the first. - I was under the impression that the BGA required parachutes for all pilots. *Wrong? *1000 ft should have been enough to get out in time but who knows what was happening in the cockpit or if she was 1000 MSL or AGL at the time. Thanks. - John DeRosa It was a Foka 4. Foka-4 was a derivative of the Foka line http://en.wikipedia.org/wiki/Foka_%28glider%29 Cobra was the next to last iteration, with 17m being the last. http://en.wikipedia.org/wiki/SZD-36_Cobra_15 Note the comments on failures. I don't know that the 4 had the same wing join design, but suspect it was very similar. There was a wing failure on a Cobra in the US and a sobering analysis. http://www.sylacaugasoaring.com/SZD%...%20WARNING.htm The SHK has an expanding vertical pin. There's an anecdotal story of someone who used the right-hand to expand the pin, and finished the job with left-hand, in the opposite direction. The wings reportedly departed at the top of the launch. The pilot reportedly pulled the tail chute on the way down. I believe that some German studies found that successful egress and parachute deployment below 600m is unlikely, of course there are exceptions. The better emergency chutes are life saving from 100ft agl at 100kts horizontal. Wing failure on a winch launch is very rare. There was a K-7 at RAF Dishforth in the UK a while back, but the investigation determined there was prior damage to the spar which was not found following another incident. There was a homebuilt in Colorado that had a wing failure due to aileron flutter during a winch launch. After two weak link breaks, the pilot doubled the weak link (unknown to the winch crew). The described flight path was one of climb, level off, climb, level off, climb, glider breakup, crash. The wing inspection hatch was found early in the flight path. What did not appear in the NTSB report was that the pilot was refused further tows at the local FBO after the glider had suffered significant aileron flutter on aero tow. I winched at RAF Bicester when it was the RAF/GSA Centre. Appropriate weak links were always used, like any UK club. It's not a long run, but easy enough to climb away on the thermal day. Steel wire rope used in many places typically has a breaking strength of 2800-3500lbs. The new UHMWPE 12-strand ropes (Spectra, Plasma, Dyneema, Amsteel) now in common use are nominally 3500-5400lbs breaking strength at similar diameters, thus use of correct weak links are essential to avoid damaging a glider as some winches have substantial power and there are also gusts and thermals to allow for. Frank Whiteley |
#5
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Wing Launch - Can it pull your wings off?
On Aug 12, 4:12*pm, Frank Whiteley wrote:
On Aug 12, 3:16*pm, ContestID67 wrote: I was sent this link from a UK soaring friend of mine about a death when the wings came off of a glider during a winch tow.http://www.dailymail.co.uk/news/arti...lunged-death-b... Sad story. *A few things; - My friend's thought was that the wing pins were left out. *Howerver, this was the second flight of the day. *Both winch launches. *So I would think that the wing pins were installed but the wings failed under a winch load. *Which glider was it? *Older? *Wooden spars? Never having had a winch launch, what happens if you don't release back pressure at the top? *Can you pull your wings off? *Maybe safeties on the pins were missed and the pins wiggled out on the second flight after staying in for the first. - I was under the impression that the BGA required parachutes for all pilots. *Wrong? *1000 ft should have been enough to get out in time but who knows what was happening in the cockpit or if she was 1000 MSL or AGL at the time. Thanks. - John DeRosa It was a Foka 4. Foka-4 was a derivative of the Foka linehttp://en.wikipedia.org/wiki/Foka_%28glider%29 Cobra was the next to last iteration, with 17m being the last.http://en.wikipedia.org/wiki/SZD-36_Cobra_15 Note the comments on failures. I don't know that the 4 had the same wing join design, but suspect it was very similar. There was a wing failure on a Cobra in the US and a sobering analysis.http://www.sylacaugasoaring.com/SZD%...%20WARNING.htm The SHK has an expanding vertical pin. *There's an anecdotal story of someone who used the right-hand to expand the pin, and finished the job with left-hand, in the opposite direction. *The wings reportedly departed at the top of the launch. *The pilot reportedly pulled the tail chute on the way down. I believe that some German studies found that successful egress and parachute deployment below 600m is unlikely, of course there are exceptions. *The better emergency chutes are life saving from 100ft agl at 100kts horizontal. Wing failure on a winch launch is very rare. *There was a K-7 at RAF Dishforth in the UK a while back, but the investigation determined there was prior damage to the spar which was not found following another incident. *There was a homebuilt in Colorado that had a wing failure due to aileron flutter during a winch launch. *After two weak link breaks, the pilot doubled the weak link (unknown to the winch crew). *The described flight path was one of climb, level off, climb, level off, climb, glider breakup, crash. *The wing inspection hatch was found early in the flight path. *What did not appear in the NTSB report was that the pilot was refused further tows at the local FBO after the glider had suffered significant aileron flutter on aero tow. I winched at RAF Bicester when it was the RAF/GSA Centre. *Appropriate weak links were always used, like any UK club. *It's not a long run, but easy enough to climb away on the thermal day. Steel wire rope used in many places typically has a breaking strength of 2800-3500lbs. *The new UHMWPE 12-strand ropes (Spectra, Plasma, Dyneema, Amsteel) now in common use are nominally 3500-5400lbs breaking strength at similar diameters, thus use of correct weak links are essential to avoid damaging a glider as some winches have substantial power and there are also gusts and thermals to allow for. Frank Whiteley Frank's analysis is excellent. I would only add that the wing spar loads incurred during a winch launch is approximately that of a loop. If a glider is not approved for loops or its age and condition is such you wouldn't loop it, don't winch launch it. Always use the EXACT weak link specified in the manual. If a glider's manual doesn't specify a winch launch weak link - you're going to be a test pilot if you winch it. Bill Daniels |
#6
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Wing Launch - Can it pull your wings off?
On Aug 13, 8:30*am, bildan wrote:
Always use the EXACT weak link specified in the manual. *If a glider's manual doesn't specify a winch launch weak link - you're going to be a test pilot if you winch it. What would be the consequence of using a link say 10% weaker than that specified? If I know the link is weaker I can fly a less agressive climb profile and accept that I will get a lower launch altitude. If I forget and climb agressively the link will break - so what? Andy |
#7
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Wing Launch - Can it pull your wings off?
On Aug 13, 10:56*am, Andy wrote:
On Aug 13, 8:30*am, bildan wrote: Always use the EXACT weak link specified in the manual. *If a glider's manual doesn't specify a winch launch weak link - you're going to be a test pilot if you winch it. What would be the consequence of using a link say 10% weaker than that specified? *If I know the link is weaker I can fly a less agressive climb profile and accept that I will get a lower launch altitude. *If I forget and climb agressively the link will break - so what? Andy I've had experience as a winch driver with gliders using weaker links resulting in frequent breakage. In that case I would suggest the pilot insisting on using the weaker link be held accountable for the cost of broken link and any lost rigging. Links are $7 (x4 in this case) and I'm still looking for a missing strop, shackle, and ring set ($100). Two went missing on a single day, with one having since been recovered. A few years ago a strop vanished and was found 4.5 years later. There are recommendations that if the correct value isn't specified or known to use 1.3 x MAUW. This is one reference to that formula http://tinyurl.com/258ba3j Frank Whiteley |
#8
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Wing Launch - Can it pull your wings off?
On Aug 13, 11:35*am, Frank Whiteley wrote:
On Aug 13, 10:56*am, Andy wrote: On Aug 13, 8:30*am, bildan wrote: Always use the EXACT weak link specified in the manual. *If a glider's manual doesn't specify a winch launch weak link - you're going to be a test pilot if you winch it. What would be the consequence of using a link say 10% weaker than that specified? *If I know the link is weaker I can fly a less agressive climb profile and accept that I will get a lower launch altitude. *If I forget and climb agressively the link will break - so what? Andy I've had experience as a winch driver with gliders using weaker links resulting in frequent breakage. *In that case I would suggest the pilot insisting on using the weaker link be held accountable for the cost of broken link and any lost rigging. *Links are $7 (x4 in this case) and I'm still looking for a missing strop, shackle, and ring set ($100). *Two went missing on a single day, with one having since been recovered. *A few years ago a strop vanished and was found 4.5 years later. There are recommendations that if the correct value isn't specified or known to use 1.3 x MAUW. *This is one reference to that formulahttp://tinyurl.com/258ba3j Frank Whiteley Again, Frank has provided a good analysis. Again I will add a few points. As frank says, a weaker than specified link will muck up the operation when it breaks. You really don't want it to break since you will then have to deal with a launch failure - usually as you load the rope while rotating into the climb. This, is NOT good. If your glider was certified with an Approved Flight Manual, as all JAR-22 gliders are, FAR's require you to operate in compliance with that manual. That includes using the correct weak link - usually specified to a + or - 10% tolerance. Incidentally, that also applies to aero tow. The old 80-200% rule only applies to gliders without an AFM. (i.e.Schweizers) If you are being launched with one of the new Automatic Tension Control winches, you must control your airspeed with pitch. Attempting to climb at a lower angle will result in an over speed condition. The bottom line is you have no choice in weak links - you must use the one specified in the manual. |
#9
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Wing Launch - Can it pull your wings off?
On Aug 13, 5:56*pm, Andy wrote:
What would be the consequence of using a link say 10% weaker than that specified? *If I know the link is weaker I can fly a less agressive climb profile and accept that I will get a lower launch altitude. *If I forget and climb agressively the link will break - so what? Andy The consequence of using a 10% weaker link would be a greater chance of a broken weak link and a failed launch, which might be hazardous in itself under some circumstances. If you use the correct link as specified by the glider designer and the glider is in airworthy condition, there should be no chance of a structural failure. All gliders in the UK have to have an annual inspection and airworthiness review. The glider that failed was a 30 year old wooden design. It has been suggested that the tapered main pin might not have been fully engaged, but the glider had survived a previous winch launch. My sincere condolences to the family and friends of this young lady pilot. http://www.bbc.co.uk/news/uk-england-10949058 Derek C |
#10
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Wing Launch - Can it pull your wings off?
On Aug 13, 5:56*pm, Andy wrote:
What would be the consequence of using a link say 10% weaker than that specified? *If I know the link is weaker I can fly a less agressive climb profile and accept that I will get a lower launch altitude. *If I forget and climb agressively the link will break - so what? Andy The consequence of using a 10% weaker link would be a greater chance of a broken weak link and a failed launch, which might be hazardous in itself under some circumstances. If you use the correct link as specified by the glider designer and the glider is in airworthy condition, there should be no chance of a structural failure. All gliders in the UK have to have an annual inspection and airworthiness review. The glider that failed was a 30 year old wooden design. It has been suggested that the tapered main pin might not have been fully engaged, but the glider had survived a previous winch launch. My sincere condolences to the family and friends of this young lady pilot. http://www.bbc.co.uk/news/uk-england-10949058 Derek C |
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