Abstract: Compound high-speed unmanned helicopter consists mainly of aerodynamic components, such as rotor, wing, propeller, fuselage, and horizontal & vertical tails. Aerodynamic interferences between components can be com-plex and vary rapidly with forward flight speed. To achieve a high level of model confidence, it is necessary to cor-rect the flight dynamics model parameters according to the forward flight speed. The aerodynamic characteristics of each component change significantly and non-linearly with forward flight speed. Therefore, the flight control scheme must be adjusted accordingly to achieve stable and controllable flight throughout the entire speed enve-lope. This paper presents a model for the flight dynamics of a high-speed compound unmanned helicopter and shows the effectiveness of correcting the model based on wind tunnel trimming tests. The method significantly en-hances the confidence of the mathematical model. At the trimming point, the non-linear dynamics model was line-arized to obtain the evolution of the open-loop dynamics with forward flight speed. The study evaluated the effect of the control augmentation system on the closed-loop steering stability performance. Based on the classical control approach, a set of practical feed-forward compensation, loop weighting, and control allocation strategies were de-signed for the compound high-speed unmanned helicopter's lift, thrust, and yaw characteristics. Simulation and test flight verification were carried out to confirm the effectiveness of these strategies. The research results show that the nonlinear dynamic model has high fidelity, and the consistency between the trim results of the mathematical model and wind tunnel tests is good. The distribution of eigenvalues of the high/low-order linear models is basically consistent, and the maneuver response characteristics are in good agreement with the nonlinear dynamic model, indicating that the low-order linear model can be used to design the control stabilization system. The flight simula-tion preliminarily validates the effectiveness of the compound strategies for rotor/wing lift, rotor/propeller thrust, and propeller/rudder yaw control. The successful flight test of the first 300kg prototype in China validates the compound flight control scheme in hover and low-speed flight and further confirms the high reliability of the non-linear dynam-ic model.

Key words: compound high-speed helicopter, flight dynamics, wind tunnel test, control scheme, flight simulation, flight test