Assessment of Helicopter Model Accuracy Through Inverse Simulation

Abstract

The paper deals with the assessment of the reliability of simplified rotorcraft models in the evaluation of maneuvering potential using inverse simulation. Inverse solutions obtained for the same maneuver from models of different complexity and fidelity are compared with the objective of identifying the most appropriate model for a consistent evaluation of vehicle handling qualities at the minimum computational cost. A total of nine rotor blade models, three main rotor inflow models, and two fuselage aerodynamic databases are combined for deriving 10 different helicopter simulation models analyzed in five maneuvers. Inverse solutions are obtained by means of an integration method for hurdle-hop, slalom, and lateral repositioning maneuvers. Once the maneuvers are solved for the baseline rotorcraft model, the uncertainty associated with the command law identified by means of simpler models is determined. The quantitative evaluation of model reliability from a set of simulation tests is further analyzed on a pop-up-pop-down maneuver and a 180 deg fast turn for validating the approach. The results show that uncertainty intervals are correctly identified, although with some degree of conservativeness when less demanding maneuvers are dealt with.