Delta IV - Fieseler F3 Wasp
Fieseler terminated the test flights in the fall of 1932. The elevators (canards?) in front of the wing were retarding stalling in the midsection of the wing, allowing the outer sections of the wing to stall at smaller angles of attack, and this led to dangerous instability. The center of pressure also shifted, making the airplane tail-heavy. Near the conditions of maximum lift, the controls were not sufficiently responsive to compensate for this shift, and at the end of the test flights the airplane was seriously damaged during landing.