Effect of Large High-Frequency Angular Motion of a Shell on the Analysis of its Yawsonde Records

Abstract : The usual data analysis of yawsonde records assumes that the sun angle is constant during one revolution of the shell and uses three successive sightings of the sun to yield sun angle and angle theta, the roll rate with respect to the plane containing the sun and the missile's axis. An improved analysis technique is described which assumes a linear variation of the sun angle and uses five successive sun sights to obtain sun angle and angle theta. For large high-frequency yawing motion, angle theta has a periodic component which is usually at the frequency of the yawing motion. An expression for this periodic component is derived and it is shown that the average of angle theta is very close to the spin rate of the shell.