Glider Crash

[BR=11=Frazer]

Amazing footage of a glider crash
(Link original thread)

Сообщение от EtherealN

Shoreham airport in West Sussex, England, Aug. 22 2010.

Anyway, more to the point:

"The pilot looked towards the ASI once, 10 seconds before impact, and stated later that, although he could not recall the indicated airspeed, he would have been aiming for 65 kt IAS."
[...]
"During the third phase, the pilot did not look left into the turn towards the new landing area or look at the ASI; his attention was fixed ahead and slightly to the left of the nose. The turn was flown with approximately 50° to 60° of bank with left rudder applied throughout. During the turn, the airbrakes were selected out momentarily four times, although they were fully extended only once, and they were selected out once more immediately before impact. When the aircraft stalled, indicated by a distinct drop in the nose attitude, sideslip was present and the aircraft departed controlled flight, impacting the ground two seconds later." (AAIB Bulletin 7/2011)

Further, this was a downwind landing attempt following a tow rope failure. This means that the pilot, who was flying 100% visually on the mark by this point, would need to establish an uncommon ground speed to achieve his proper airspeed. Add to this the 50-60 degrees of bank (way more than I would use normally) and you suddenly have a 49-55 knot stall speed. Add the visual mirage from contact-flying the approach, and deployment of Shemmps (as you can see in the picture) right there, and the inside wing will stall. It's not really that he ran out of speed per se - he literally destroyed a major portion of the inside wing's lift using the Shemmps (the "airbrake") while in a profile that places him right on stall limits even when clean... Add some sideslip and departure is guaranteed.

(And while I sound damning there, reading through the accident report I can't say I'm sure I would have acted differently. The accident report is also a bit weird since it only explicitly states "added drag" as an effect of those airbrakes being deployed, which is false. There is added drag, obviously, but the bigger deal is that it largely spoils the lift from a large section of the aerofoil - those are not used to reduce airspeed, they are used to adjust sink rate. Normally you plan your final such that you'll fly through it with shemmps at 50% - that way you can adjust either way as necessary.)

Another example of something similar:
http://www.youtube.com/watch?v=zfFGN-3Yglo

[BR=34=Gosha]

[BR-Aviator]

[BR=22=Sawamura]

Lucky guy.

[Roman]

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