Abstract: To calculate accurately the effective aerodynamic parameters of a helicopter in different flight states is of crucial importance to the determination of its flight performance. However, it is not easy to estimate these parameters precisely due to complicated rotor aerodynamics and changing environment and helicopter states. In this article, a non-dimensional mathematic model is built for the helicopter hovering state, and a number of important parameters of the helicopter, including its aerodynamic parameters and certain state parameters, are developed by regrouping. Then, taking helicopter Z-9× as an example, the least squares method is proposed to identify the dynamic parameters of the mathematic model on the basis of actual flight test data. Finally, the identification method is proved valid through feasibility analysis, and these identified parameters are effectively used to expand the helicopter’s hovering performance. The results show that it is feasible to use the parameter identification method to expand helicopter hovering performance, and the expanding results have high reliability since the identified parameters are derived from actual flight data. It is believed that this flight data measurement method can reduce flight test periods and save test cost as well.

Key words: helicopter, hovering performance, parameter identification, flight test, the least squares method, feasibility analysis