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. armys 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.