2126. Measuring Moments of Inertia of Aircraft and Spacecraft

Paper

Abstract

Moments of inertia of aircraft are needed in order to make evaluations of flying qualities and aircraft response to atmospheric disturbances. This paper presents a historical perspective of early methods of measurement of moments of inertia including a description of various test rigs involving compound and bifilar pendulums. Also, an early technique for obtaining the vertical center of gravity location by swinging the aircraft at two different pendulum lengths is described. Four techniques for determining moments of inertia are reviewed from the standpoint of sensitivity, accuracy, and complexity. A small working model to illustrate the methods was built so that theoretical and experimental results could be compared.