Also found in: Dictionary, Wikipedia.
an aircraft spin in which the longitudinal axis is more nearly horizontal than vertical
flat spin[¦flat ′spin]
Motion of a projectile with a slow spin and a very large angle of yaw, happening most frequently in fin-stabilized projectiles with some spin-producing moment, when the period of revolution of the projectile coincides with the period of its oscillation; sometimes observed in bombs and in unstable spinning projectiles.
A spin in which the aircraft longitudinal axis remains at less than 45° below the horizontal. A flat spin is a stabilized spin. The farther back the center of gravity and the more the masses that are distributed along the length of the fuselage, the flatter and faster the spin tends to become and the more difficult it is to recover. This is because it is difficult to reduce the angle of attack to unstall the aircraft even with full application of the elevator control.