I built and flew a nitro model 40 gas pitts using a tower hobbies 46. On the third flight, the right wing began to flutter uncontrollably, and regretfully the plane was lost. I looked at the rubble, and noticed that some of the attachments that screwed to the wing braces between the lower and upper wing had pulled loose. I attributed this to the crash, but later had another idea. When I put it together, I noticed that the upper wing brace attachment points were about 1" further apart than the lower wing attachment points. Thus in order to get a straight brace between the two wings, the brace had to bend inwardly, thus imparting a stout bending force on the 1/16" ply attachments. Could it be that that force combined with the G forces of flying pulled out the attachments? The nitro model rep. said that it was designed to have a bent brace. Seems kinda stupid to me, all the other biplane braces are straight. I love the plane and want to buy another, but don't want to go thru the same problem. When the flutter began, I was only half throttle.