Abstract: Flying wing combat aircraft adopts a tailless blendedwingbody configuration,which leads to the decline of stability and damping.Therefore the control surface must possess good characteristics to ensure good flying quality in the short period mode.Three flying quality criteria are adopted to assess the flight quality of a lowaspectratio flying wing aircraft with different control surface characteristics,and the relationship between control surface characteristics and short period flying quality grade is summarized.The short period flying quality boundary assessed by the control derivative values and deflexion rate is introduced.The result indicates that the flight quality of the flying wing aircraft tends to become worse if the control surface exhibits poor performance characteristics.The research method and results can be used to guide the preliminary design and flying quality evaluation of new configuration aircraft.

Key words: flight dynamics, flight quality, short period, control surface characteristic, fighter aircraft, flying wing, deflexion rate