3238. Measuring weight and all three axes of center of gravity of a rocket motor without having to reposition the motor
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Paper
Abstract
Large live rocket motors are dangerous and time consuming to move. Therefore, it is advantageous to measure mass properties with a minimum of handling operations. This paper describes an instrument, which is capable of measuring weight and all three axes of center of gravity in a single setup. Two axes are measured using a reaction type two-axis CG instrument. The mounting surface of the machine then tilts to measure the third axis. By using force restoration technology and flexure pivots, CG measurement accuracy is in the order of a few thousandths of an inch. Weight and CG are measured independently by using a parallelogram structure with a single force transducer, upon which are mounted the X and Y moment measuring structure. This permits optimization of the design. This paper discusses details of the process and the means of verifying the accuracy of the instrument, using a mass properties standard that has been designed to permit the application of work reversal techniques.
