480. Mass Properties Program for the 156-Inch Diameter Solid Propellant Rocket Motor
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Paper
Abstract
On 12 December 1964, the largest, most powerful solid propellant rocket motor ever tested to that date was fired by Thiokol’s Wasatch Division for the U.S. Air Force.
That successful firing of the 156 inch diameter large booster motor verified the accuracy of the techniques and procedures used to determine theoretical and actual mass properties data. This paper describes the analytical procedures used for mass properties predictions and the techniques for obtaining actual weights during the fabrication and test of the 156 inch diameter motor. This motor employed an omniaxial gimbaled nozzle thrust vector control system and attained a thrust level of 1.4 million lb during the 130 sec static test firing. It weighed 772,216 lb, was 78 ft in length, and had a mass fraction of 0.894.
Mass properties analyses were performed utilizing a new computer program (1) to insure that contractual incentive requirements were met, (2) to support weight versus cost tradeoff studies, and (3) to provide weight control of components and assemblies. Motor weight was predicted to within 0.6 percent of the measured weight.
Methods for determination of actual mass properties measurements utilized a unique 100,000 lb capacity hook, an advanced storage and transporting trailer and a computer calculated correction table to translate the weighing system indications to weight. The corrective procedure represents a considerable improvement over the linear or additive correction factors normally used.
The handling techniques, linear measurements, and methods used to determine the longitudinal coordinates of the centers-of-gravity for the nozzle and loaded case segments are discussed.
Results of the program have demonstrated that (1) an efficient mass properties program can be conducted at minimum cost; (2) there is a need for positive vendor mass properties control programs; (3) computer techniques reduce costs when applied to the generation of mass properties data; and (4) the weighing of motor segments ranging up to 400,000 pounds is feasible.
