Assessment of go-around climb gradient for civil aircraft based on digital virtual flight

The climb gradient of the aircraft reflects its ability of flying over the ground barrier to a safe altitude. To ensure safety of civil aircraft when going around, airworthiness regulations provide that the go-around climb gradient should meet certain numerical requirements. According to provisions of airworthiness regulations on go-around procedure and go-around climb gradient of civil aircraft, an airworthiness compliance assessment method of go-around climb gradient was proposed based on digital virtual flight. The task digitized model of go-around and pilot control model were established based on the airworthiness regulations as well as the characteristics of pilot control. Then the flight dynamics model of a certain domestic turbojet aircraft was established, which eventually constituted digital virtual flight simulation system for go-around task. The climb gradient evaluations of landing climb and approach climb were completed by flight simulation. Compared with the real flight test results, the evaluation errors are less than 10%, which verifies the applicability and accuracy of the method. This method can be applied to the design of civil aircraft, so as to provide support for determining the airworthiness compliance of go-around climb performance and the maximum landing weight of aircraft.