Effect of canard stall on projectile roll and pitch damping

Abstract

A computational and mathematical approach is used to investigate the effect of canard stall on projectile roll and pitch damping. For spinning projectiles with dithering canards, large angles of attack can be achieved by these canards. These large angles of attack can lead to stall that causes abnormal loads on the projectile. Because of these abnormalities, it is important to include the effects of stall on the projectile. First, the total roll and pitch moments of two canards is derived. These equations are then analysed to show that the effects of canard stall can produce a decrease in roll damping, causing roll rate to increase, and an increase in pitch damping, causing the no roll frame pitch rate to decrease. To validate this analysis, simulation is performed using a fully non-linear six-degree-of-freedom dynamic model with canard aerodynamics. The results from the simulation agree with the equations derived; thus, for projectiles that use dithering canards for control, it is important to include these non-linear effects in the projectile dynamic model.