Uncertainty Quantification for Rotorcraft Simulation

Abstract

This research investigates the impact of modeling uncertainties on helicopter handling qualities and simulator tolerances as prescribed by ADS-33 and JAR-STD. Using a six-degree-of freedom linearized model of the Bo105 helicopter, the analysis focuses on the propagation of stability derivative uncertainty on four Quantities of Interest (QoIs): Pitch Quickness, Roll Quickness, Pitch-Due-To-Roll Cross-Coupling, and Roll-Due-To-Pitch Cross-Coupling. These QoIs are evaluated across the flight envelope, from hover to maximum velocity (145 knots), capturing sensitivity variations with flight con ditions and advance ratios. To propagate uncertainty, two methods are employed: Monte Carlo Simulation (MCS) and Polynomial Chaos Expansion (PCE), with PCE reducing computation time by 98% while maintaining accuracy. Each QoI shows greater sensitivity to uncertainty at the extremes of the flight envelope. Pitch Quickness is most sensitive at high speed, whereas the other QoIs are most sensitive at hover. Cases
with both JAR-STD tolerance violations and ADS-33 HQR level changes show JAR-STD tolerances are generally more stringent, except for the Cross-Coupling QoIs, where ADS-33 level changes are more frequent.