Flight data on liquid-filled shell for spin-up instabilities

The stability of a spinning projectile can be adversely affected when a liquid payload is present. Due to the impulsive launch of a spin-stabilized projectile, the liquid payload is subjected to unsteady and time-dependent processes. For example, the liquid must adjust to the rapid spin of the projectile casing. This process is normally called liquid spin-up. Typically, the liquid spin-up process encompasses a large portion of the trajectory, and in fact many flight instabilities have occurred during this spin-up time frame. Flight data for spin-up instabilities of 155 mm projectiles are presented and discussed.