Study of dynamic characteristics of aeronautic towed decoy system

To predict whether the aeronautic towed decoy system can disturb successfully or not, a mathematical-physical model of the system is built and its dynamic characteristics are studied. The lumped-mass method is applied to building the dynamic model of the cable, which disperses as a series of nodes connected by damping springs. Forces of the decoy are analyzed and its model of six degrees of freedom is established. Conditions in which the cable and the decoy are coupled are considered in order to make the model more accurate. The dynamic characteristics are simulated during the decoy release and the aircraft maneuver, respectively. The shape and tension of the cable and attitude angles of the decoy are given and analyzed. The results show that to avoid the phenomenon of "fish hook", the release direction should be almost parallel to the aircraft airspeed. The release rate of the decoy should be trapezoidal to reduce the maximum tension in the cable. The maximum airspeed of the aircraft should be controlled after completing release to avoid the cable entering the exhaust jet of the aircraft. The cable is outside the circular trajectory of the circling aircraft. The greater angular velocity of the aircraft with constant speed is, the greater outward trend of the cable is, which is beneficial to avoiding the aircraft exhaust jet.