Actually some airplanes do require aileron's to recover from a spin. I fly a T-45 (it's a jet though) that requires ailerons into the spin and rudder opposite. Inverted it requires ailerons AND rudder opposite the spin. You would think that with these prop driven airplanes that if anything, full power would force airflow over the elevator and allow some control (push the nose down to get more airflow over the wing or even give airflow over the inboard section of the ailerons that would allow you to roll out of it). Never flat spinned an airplane though, so I'm just guessing.