Similarity Relations of PID Flight Control Parameters of Scaled-Model and Full-Size Aircraft

To carry out a scaled-model flight test of a high-gain aircraft with a proportional plus integral plus derivative (PID) flight control design, the similarity relations of the flight control law parameters of scaled-model and full-size aircraft must be systematically studied. In this article, the general similarity relations applicable to commonly used flight control law configurations and feedback signals are derived and analyzed. Based on the control principle, PID control parameters are divided into two types: feedback gains and series combined dynamic elements. The general similarity relations for the control parameters of these two types of elements are derived from system similarity theory. Finally, closed-loop flight control simulations of a fighter aircraft and its scaled model are completed. The simulation results show that the scaled-model and full-size aircraft with similar PID control law parameters are physically similar, validating the similarity relation conclusions proposed in this article.