Abstract
A three-sigma (−3∼+3) approach is applied in robust design optimization of Finocyl grain geometry. Grain design becomes an exigent task when accounting for uncertainties in manufacturing processes. Upper stage SRM requires tight control on total impulse and acceleration to ensure safe entry of satellites into orbits. A first order Taylor series is used to calculate solution sensitivity and thus moving toward a robust solution. Motor performance is calculated using a simplified ballistic model with throat erosion considerations. Average thrust and propellant mass are the impetus drivers on performance, and so considered as core of grain design process. Therefore, we intend to maximize them with minimizing the variation in both. Monte Carlo simulation reveals that robust solution proves insensitive to manufacturing uncertainties. The approach produced satisfactory results for test case.