The flying qualities of the seesaw ducted fan configurational unmanned helicopter with an elastic support on the hub was evaluated for the stability
maneuverability and inter-axis coupling based on the U.S. armys aviation design standard ADS-33E-PRF. The flight dynamic model of the sample unmanned helicopter was introduced. The stability
maneuverability and inter-axis coupling in ADS-33E-PRF were pruned applicably based on the flight control characteristics of unmanned helicopter. By taking the sample helicopter with elastically supported blade roots as an example
the characteristics in trimming and flying qualities parameters of different stiffness of elastic restriction were computed
and the flying qualities of the sample unmanned helicopter were evaluated
compared and analyzed based on the flying quality evaluation methods. The comparative and analytical results show that the stability
maneuverability and inter-axis coupling of flying qualities are all influenced by the stiffness of elastic restriction
and the stiffness coefficient about 1 is more appropriate.