Based on the engineering reality

a calculation model of the rotor unsteady aerodynamics of the small-scale coaxial helicopter had been set up.An airfoil unsteady aerodynamic model was established by introducing a set of Leishman-Beddoes semi-empirical indicial response formula.The induced velocity of the aerodynamic interaction between upper and lower rotors of a coaxial helicopter was set up based on the rigid wake model

free wake model and the dynamic inflow model with interference factors.Considering the teetering rotor’s particular flapping dynamic formula

the Runge-Kutta method was used to obtain the numerical solution of the rigid blade flapping angle.According to the calculation and analysis

the thrust response to a rapid collective pitch increase in both the hovering and forward flight states were obtained

and the blade’s hinge moment of the upper and lower rotors were compared.