Dispersion of Spinning Missiles due to Lift Nonaveraging

Abstract

A new source of cross-range dispersion is identified for spinning missiles during untrimmed flight. The dispersion is caused from wind-fixed moment disturbances that produce coupled perturbations in angle of attack and lift vector precession rate, in contrast to body-fixed moment-induced dispersion of a rolling, trimmed missile in which lift and roll variations generally are uncoupled. Small wind-oriented moments can affect the precession rate adversely and cause lift nonaveraging. The dispersion, in some cases, depends strongly on the initial motion conditions. Since roll rate has little influence on the lift vector precession rate, roll control is ineffective for limiting this type of dispersion, and effective control must provide some means of maintaining a steady, nonzero precession rate.