On Saturday, June 27, 2015 at 7:07:58 AM UTC-7, JJ Sinclair wrote:
Time for another JJ story. We were finishing at Ephrata at 50 feet and 140 knots in our ASH-25 (with 2 meter wing extensions). As I crossed the finish line, I pulled up and rolled left,. At about 45 degree left bank, I applied right stick to stop the left roll............IT KEPT ROLLING LEFT................I then applied full right stick and rudder and the left roll stopped, but by then we were in a 75 degree left turn. The nose was up, so as airspeed slowed, the ship slowly responder to right stick commands.
After landing, I talked to the guy running the finish gate who was looking right down our wing as we flew through the gate...........He said it was the scariest thing he had ever seen! The wing tip leading edge, twisted down and doug-in, resulting in the un-commanded left turn, the rest of the wing looked like a sign wave. The wing extension had been somewhat blessed by Schleicher who had us install some 12# of lead in the outboard leading edge.. I believe it was to prevent flutter, but probably aided the twist problem.. Any aerodynamic experts explain why the lead was placed in the leading edge? Didn't it help twist the wing leading edge down?

Not too long after that, I sold the ship and retired to the peace and tranquility of the finish cylinder in sports class.
JJ

Happened to my Dad doing Max Q pull-ups while flight testing an F-86. The aileron acted like a trim tab for the entire wing. Not fun at transonic speeds.

I don't have a precise answer for the lead in the leading edge. Aeroelastics are complex, but presumably they want the leading edge to twist downward under loading so that there is a restoring force from whatever input perturbs the wing. Make sense that this could increase the resonant frequency and delay the onset speed for flutter and/or add some damping effect, but obviously it had a second consequence for you.

9B