The critical influential factors limiting the flight performance of conventional multi-axis aircraft were analyzed. The method to improve the flight performance of multi-rotor aircraft was studied by means of variation of rotor collective pitch and rotational speed. Based on dynamic stall

unsteady flap and dynamic inflow model

a comprehensive aerodynamic theoretical model was developed to analyze the flight performance. A demonstrator multi-axis rotor aircraft was developed for flight test. The flight experimental results and theoretical results showed that the aircraft required power increases obviously with the increase of takeoff weight. Under different payloads and rotor rotational speed conditions

experimental and theoretical required very good agreement of the power results up to 97% at light load reach and 95% at heavy load respectively. By means of comparison and analysis

the theoretical performance analysis method was validated. And furthermore the simulation demonstrated that variation of the rotor collective pitch and rotational speed evidently improved maximal take-off weight and flight duration of multi-axis aircraft.