Analytical modeling and verification experiments of small electric helicopters with stabilizers based on the blade-element approach

Abstract

Aiming at the flight control design of small helicopters for large flight envelopes, a comprehensive modeling of small electric helicopters, based on the analyses of main blades divided into elements on which air speeds and aerodynamic forces are calculated, is performed. First, coordinates that are suitable for clockwise rotors are determined, and then, mathematical expressions of the blade motion dynamics are derived. Next, the interaction between the stabilizer and main blades by linkage mechanisms is modeled to represent it as the bidirectional transfer of blade angles and forces. Stabilizer equations of motion are derived on the basis of harmonic decomposition and high-frequency mode deletion to make them numerically stable and less complex. The developed model is validated by a comparison between simulation results and flight test data using a 2.5-kgf lightweight, ultra-small electric-driven helicopter. It is confirmed that dynamics precision of the developed model is good and suitable for flight control system development and evaluation. In addition, several studies about the development and the operation of autonomous small helicopters are made based on the result of flight performances and dynamics analyses by using flight envelopes and frequency responses calculated by the developed comprehensive model.