Pseudospectral-Method-Based Framework for Rotorcraft Stability and Trim Analysis

Abstract

The paper demonstrates applications of pseudospectral-method-based framework to rotorcraft dynamics. The framework is developed to incorporate blade-to-blade symmetry (fast-Floquet) to reduce computational time. The methodology is applied to compute Floquet exponents of an isolated rotor in forward flight using the periodic eigenvector equations, and computational performance is assessed. The framework is also applied to a trim problem that determines time-varying control input for equilibrium, as well as meets stability criteria in the form of minimum damping of the system at a prescribed value. Through the applications considered, the paper brings out the advantages of the use of the pseudospectral framework, particularly its amenability to problems that involve optimization.