Appropriate Offset Correction Procedure for Flight Measured Pressure in Launch Vehicle Compartment Venting Analysis

Abstract

Appropriate offset correction procedure for flight measured compartment pressure values has been discussed in this paper. Compartment pressure is essential in the overall load computation of launch vehicle structures. Prediction and measurement of internal pressure plays a major role in the venting analysis, structural design and analysis. Any offset/bias in the measured pressure at the sea-level conditions will reflect in the flight measurements till they get saturated during the flight. In this paper, a typical launch vehicle flight measured compartment pressure is presented with appropriate bias correction. The offset corrected values should also reflect the trend in the aerodynamic characteristics, like the external pressure variation at various Mach numbers and angles of attack. Initial offset correction using channel offset procedure, adding a constant bias and applying a multiplication scale factor to all the flight measured values gave different results. Results obtained from these initial offset procedures are compared against other flight values. The offset correction methodology is also validated with cone-cylinder type PLF venting results.