Effects of wing on autogyro longitudinal stability

Based on a gyroplane, a nonlinear mathematical model of coupled equations described by the state space method is presented in this paper in order to study the effects of the wing on autogyro longitudinal stability. The model consists of an aerodynamic model (which includes an autorotating rotor, a fuselage, a propeller, and a wing and a tail aerodynamic model), a dynamic inflow model and a stability analysis model. The model is applied to study the sample autogyro and sample gyroplane longitudinal stability. By contrastive analysis, the results show that the wing is favorable for phugoid mode and short period mode stability. It is unfavorable for rotor speed mode stability but the rotor blade tip weight could be increased to improve the mode stability when the gyroplane is designed. The wing longitudinal position has a significant influence on the autogyro longitudinal stability. When the wing longitudinal position satisfies the trim constraints, the more rearward the wing is located, the better is the angle of attack stability of the gyroplane, but the worse is its rotor speed stability. The wing longitudinal position should be selected eclectically by considering these two factors when a gyroplane is designed.