I think the larger engine they fitted for the speed record atempts was part of the problem also. Sadly, the Z won everything it entered with the Wasp Jr motor, they had to put the 750hp Wasp motor in and go faster.... I read somewhere that the wing at higher speeds had a flutter problem. You can see that the right wing outboard of the bracing wires breaks off. Sad end for a magnificent craft and brave pilot, Lowell Bayles. The replica Z that Bill Turner built and the R2 flown by Delmar Benjamin show that the Gee Bees were good designs for their day.