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WW2 Glider Pilots

Old 2nd Dec 2019, 20:12
  #21 (permalink)  
 
Join Date: Dec 2007
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Originally Posted by washoutt View Post
What a fascinating instruction movie. It shows that necessity is the mother of inventions!
What I do not understand however, is how the shock of the sudden load due to the build up of zero speed to 130 miles on the glider is gradually applied, so that the airframe is not pulled apart by the increase of impulsl. Is it all in the elasticity of the nylon rope?
I remember that when needing to tow a car to the garage in the sixties (when cars still could stall and stop driving), we used a tow rope on the tug car, a pair of old bycycle tires tied to the other end, and then a rope attached to the stalled car tied to the other end of the bycle tyre. The resulting ovalisation of the tyres was the needed elastics to put a gradual speed built-up on the towed car and dampen the shocks of pulling.
So how was this achieved in the case of glider towing? Can any body shed light on this?
Extract from ...

https://ps.ci.lubbock.tx.us/docs/sil...rsn=191cd8c6_2


The use of tow ropes made of nylon fiber developed by the E. I. DuPont Company greatly enhanced glider "snatch pickups." This fiber, when woven into a rope, was elastic. It would stretch 25% to 30% of its length and thus absorb much of the shock as the glider became airbome. The rope would then retum to its original length. Because of this characteristic, the average acceleration for pickup was only 7/10 of one G, which according to AAF Manual No. 5- 17, lasted about 6%2 seconds. This is significant if you consider that pilots catapulted from an aircraft carrier experience 2% G's. The glider would usually become airbome in no more than 200 feet. Twin-engined Douglas C-47 transports were the primary aircraft used to test the Model 80C pickup system. Several were retrofitted with the device for the tests. The M-80C Glider Pick-up Mechanism, as it was officially designated by the AAF, consisted of a controllable, motor-driven, energy absorbing drum containing 10003 feet of flexible 5/8"steel cable, twin pulleys, torque tube, hydraulic cylinder and explosive cable cutter controls. The mechanism was bolted to the floor on the left side of the cabin about six feet from the front bulkhead of the aircraft. The reel was equipped with friction clutch that could be adjusted for different glider weights and speeds. The amount of cable played out was directly proportional to the weight of the glider and the nature of the acceleration of the glider after the pickup. Under most circumstances the cable pay-out was usually less than 600 feet. The maximum designed load of the pick-up unit was 8,000 pounds.

In addition to the normal crew of a pilot, copilot, crew chief and radio operator, the retrieval aircraft required a winch operator. The aircraft crew chief and radio operator assisted the winch operator if necessary. The winch opera- tor's function was to properly set the pickup drum clutch snubbing adjustment, which was based on the glider's weight and the aircraft's proposed speed at the instant of the cable hook/ glider rope loop engagement. The drum manufacturer (General Aviation) provided a chart with recommended snubber settings for various glider weights/aircraft contact speeds, etc. The shock of the initial contact with the nylon rope was the critical moment that placed the greatest stress on the flexible steel cable. At the very instant of "snatch" the winch operator's judgment received its most critical test. A misjudgment could result in a broken cable and possible severe injury to the operator or damage to the aircraft, or both.
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Old 3rd Dec 2019, 10:47
  #22 (permalink)  
 
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Thanks Longer On, good information. So it was indeed a matter of elasticity to avoid the longerons being pulled apart...
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Old 3rd Dec 2019, 18:01
  #23 (permalink)  
 
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One of the TPs on D Sqdn at Boscombe in the 70s was a Major Ken Mead AAC (later Lt Col.) Chatting to him one day and he mentioned, in passing, that he was an ex Glider Regt. WW2 pilot (Staff Sgt?). Didn't elaborate but likely to have been on 'Market Garden'. A total 'English Gentleman' and an absolute pleasure to have known him.
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Old 3rd Dec 2019, 20:34
  #24 (permalink)  
 
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Originally Posted by washoutt View Post
Thanks Longer On, good information. So it was indeed a matter of elasticity to avoid the longerons being pulled apart...
Initially yes but also relied on the Tug winch being set correctly and paying out the cable at the correct rate to control the acceleration of the glider,the winch operator had to be switched on and was crucial to a successful 'Snatch'.

I always loved a good 'Snatch'
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Old 3rd Dec 2019, 22:10
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Originally Posted by Cornish Jack View Post
One of the TPs on D Sqdn at Boscombe in the 70s was a Major Ken Mead AAC (later Lt Col.) Chatting to him one day and he mentioned, in passing, that he was an ex Glider Regt. WW2 pilot (Staff Sgt?). Didn't elaborate but likely to have been on 'Market Garden'. A total 'English Gentleman' and an absolute pleasure to have known him.
His Times obituary here: https://www.thetimes.co.uk/article/l...uary-b5tzsxccd
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Old 4th Dec 2019, 09:07
  #26 (permalink)  
 
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Snatch launches of Horsa gliders were also successfully made as can be seen in these AFEE trial photos. In this case the glider's AUW was up to 9400 lb ie well over the Model 8 winch's maximum design load of 8000 lb.
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Old 4th Dec 2019, 12:12
  #27 (permalink)  
 
Join Date: Feb 2000
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Warmtoast - thank you for that link - yet another of the 'good guys' gone.
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