Flying qualities evaluation criteria design for scaled-model aircraft based on similarity theory

In the preliminary design phase of aircraft, evaluating the flying qualities characteristics of full-size aircraft preliminarily through scaled-model flight test helps to shorten cycle times and reduce the technical risks of aircraft development. In this paper, the flying qualities evaluation criteria for scaled-model flight test are designed. In order to make full-size aircraft and scaled-model dynamically similar, the similarity relations between their configuration parameters, control law parameters, and flight condition parameters are analyzed. In addition, the change rules of four different flying qualities parameters with the scale factor of aircraft size are analyzed, including time-domain, frequency-domain, low order equivalent system (LOES)and pilot compensation. According to the obtained change rules, the flying qualities evaluation criteria applicable for scaled-model are designed by modifying the evaluation criteria for full-size aircraft. Finally, the flying qualities evaluations of a sample full-size aircraft and its 1/4 scaled-model are conducted, and the results show that the flying qualities evaluation of scaled-model can reflect the flying quality characteristics of the full-size aircraft accurately.