Research On High-Angle-of-Attack Characteristics And Control Law Of Fighter

In modern air combat,the fighter’s maneuverability is very important.When the angle of attack is high,the aerodynamic forces experienced by fighters are non-stationary,asymmetric and delayed,and it may have dangerous phenomena such as inertial coupling and wing rock.Aiming at the above problems,this paper analyzes the characteristics of deep stall and spin of the fighter at high angle of attack,predicts the safe area,and studies the design of control law.The main research contents and results are as follows:Firstly,using the aerodynamic data of conventional fighters published at home and abroad,a six-degree-of-freedom dynamic model and atmospheric model of high angle of attack were established,and the differences between high-angle aerodynamic modeling and general fighter aircraft were introduced in detail.Based on the establishment of the model,the maneuverability and stability of the fighter at high angles of attack were analyzed,which laid the foundation for the following research.Secondly,the bifurcation analysis is used to calculate the fighter system’s equilibrium surface with the rudder based on a continuous algorithm.Aiming at the nonlinear model of the fighter,the bifurcation surfaces are solved with the elevator,aileron and rudder as continuous parameters,and the dangerous state points such as deep stall and spin are predicted,analyzed and time-domain simulation.Then,the attainable equilibrium set is used to obtain the fighter’s maneuverability in a restricted state.A three-dimensional maneuverable attainable equilibrium set is designed to calculate the safe area of the pitching and the rolling maneuvering area around the speed vector axis,respectively.The root trajectory changes in the states of pitch maneuvering and rolling maneuvering about the speed axis can be obtained,and different maneuvering states can be obtained Regularity of lower rudder deviation.Finally,the dynamic inverse method is used to solve the control law at high angle of attack,and the high angle of attack maneuver is simulated and verified.An automatic control system for anti-deflection and spin is designed.Simulation verification and comparison of dangerous state recovery are based on PID control and dynamic inverse control,respectively.Simulation results verify the effectiveness of the proposed control system and dynamic inverse control law.