In order to analyze the aerodynamic characteristics between aero-engine and aircraft

and to accurately determine the lift-drag characteristics of aircraft under practical use condition

numerical calculation was conducted for a half aircraft model with powerplant. Then the numeical calculation method of three-dimensional flow field was verified with wind-tunnel test data

and the rules of the spillage drag and exhaust interference drag were summarized. Results suggest that: the variation of aero-engine settings has significant influences on the lift-drag characteristics of aircraft. The spillage drag component in lift and drag direction separately increases and decreases with the increase of capture area ratio. The larger difference between real operating condion and reference conditon means the larger absolute value of interference drag components.