The Use Of Discrete Rotating Virtual Blades To Suppress The N/Rev Oscillations In Flight Mechanics Analyses

Abstract

For flight mechanics applications such as handling qualities evaluation, real-time simulation, and flight control system design, a nonlinear rotorcraft simulation model with a reasonably accurate representation of the flapping dynamics is usually considered mandatory. If this is the case, the introduction of the complete flapping dynamics into the model will induce oscillating loads at the rotor hub. This, in turn, creates significant complications in the computation of a correct trim and linearization of the rotorcraft as well as in the execution of stability and control analysis. In the paper, a novel approach to remove such oscillating loads from the nonlinear model, thereby simplifying the trim, linearization, and analysis effort, is presented based on the concept of discrete rotating virtual blades.