Yaw Control of a Blunt-Nose Projectile at High Angles of Attack Using Strakes

An experimental study was conducted to investigate the effects of different aftbody strakes on a projectile with a blunt-nose and a fineness ratio of 4. The effect of strake parameters such as shape, locations (axial and azimuthal), deployment height, and in some cases, the number of strakes implemented was examined. The main objective for the study is to identify promising strake configurations for effective yaw stabilization and control, and to identify changes in the effect of actuator parameters as a function of angle of attack. Wind tunnel experiments were conducted for angles of attack ranging from 0 to 64 deg at a Reynolds number of 0.19 x 10 6 and Mach 0.1. A few test cases were conducted to examine the effect of sideslip angles. The optimum azimuthal location for a strake was found to be the left and right side meridians and 1-inch (x/L = 0.083) from the nose apex. Large yaw control authority was attained for α > 40 deg. The largest yaw control authority was produced by a rectangular-shaped strake. The yaw control attained with this strake was close to symmetric with the strake placed at the corresponding left and right side meridians, and produced a side force and yawing moment to the opposite side of where it was mounted. Aftbody strakes were effective even at sideslip conditions and with larger fins.

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