Abstract:

A nonlinear flight dynamics model is established for helicopter large amplitude maneuvering flight simulation which takes into consideration the effects of unsteady aerodynamics and dynamic stall, dynamic wake distortion induced by maneuvers, elastic deformations of blades and engine dynamics. A coupled flap-lag-torsion elastic blade model is formulated based on the finite element method and the coupled rotor/fuselage equations of motion are presented in explicit form using a novel numerical method. Thus, the entire model is presented in finite-state form. As an example, a pull-up maneuver of helicopter UH-60A under high speed flight condition is simulated. The correlation of the results with the flight test data is provided. It is shown that the results agree well with flight test data and the primary contribution to the discrepancy of the simulation of the motions of the rotor and fuselage comes from inaccurate prediction of the unsteady airloads on the blades of the advancing side in the nose-up process.

Key words: helicopter, flight dynamics, maneuver, unsteady aerodynamics, flight simulation