Quote:
Originally Posted by mswhin63
Plane stalled after a turn and the pilot tried to level out after the turn. Lucky only minor injuries.
|
Yeah, looks about right Malcolm. Brilliant bit of flying...corrected just in time to get the wings level...which means it wasn't control failure either.
***Don't mean to patronise anyone***
These types of aircraft trade-off aerodynamic buffers for pure performance. Reducing washout allows a stall to come quite quickly rather than progressively. They can do this because they pull hard in practice so often they get a good feel for it (like drifting a Go-Kart), also their flying weight doesn't change dramatically as they fly for only short periods.
What's Washout?: a twist in the wing from root to tip. Typically positive at the root and sometimes negative at the tip (Spitfire has 2+ to -1/2). The idea being that as the turn gets harder and the wing's angle of attack (A0A: angle with respect to the relative air flow) increases leading eventually to a stall (de-lamination of air cross the top surface of the wing accompanied by turbulent flow) the root will stall first while the tip is still pulling. This allows a stall to be manageable and progressive. Drop the washout down to zero and the stall comes quite rapidly.
The benefit of zero degree washout is that the wing pulls harder at the top of the lift bell curve...and of course every bit of racing advantage they can get, they take.
If you look at the clip, his last turn was to the left, which means the AoA of the left wing is increasing as it is moving downward (the right wing is decreasing the AoA). If you replay it and look closely, you'll see the wing lets-go very fast.
http://www.youtube.com/watch?v=6rR68OIpcX4
I reckon if he was 10ft higher, he would have got out of that.
