ENHANCING ACCURACY IN BURNOUT TIME ESTIMATES IN BURN RATE EVALUATION OF SOLID PROPELLANT BY FIRST DERIVATIVE APPROACH

Abstract

Burn rate of solid propellant is an important ballistic parameter for performance evaluation of Solid Rocket Motors. Normally burn rate is evaluated by testing of small-scale solid rocket motor with neutral pressuretime profile at designated test pressure. Method adopted the most widely used tangent bisection method uses ratio of web-to-web burnout time to determining burn rate. Accurate determination of burnout time occupies an obvious importance. In the present methods, burnout time is estimated by drawing a tangent at the peak of the Pressure-Time (P-t) curve at aft end. This approach poses limitations when applied to P-t curves exhibiting nonlinear post-burnout pressure decay or varying slopes. Such conditions often result in misaligned tangents, leading to erroneous burnout time estimates and consequently inaccurate burn rate estimations. This paper introduces the first derivative method as a more robust alternative for determining burnout time for neutral and nearly neutral pressure time profile. In-house application has been developed for automatic burn rate estimation using the first derivative method. The method has been validated with large numbers of Ballistic Evaluation Motor (BEM) tests with test pressures ranging from 3.3 MPa to 7 MPa. The first derivative method offers a significant improvement over traditional techniques, providing more reliable burn rate estimations, enhancing burn rate accuracy.