Nonlinear flutter analysis of missiles with pneumatic fin actuators

A method for flutter analysis and design of missiles with pneumatic fin actuators is presented. The method combines state-space aeroelastic models with nonlinear pneumatic models for time-domain simulations and for frequency-domain approximate solutions. The missile and its fins are represented by normal modes with the generalized unsteady aerodynamic force coefficients approximated by rational functions. Time simulations are presented for various velocities, maneuver commands, and pneumatic parameters, and the system behavior at the flutter boundary is discussed. It is shown that the fundamental fin flutter speed is strongly dependent on the missile maneuver commands. The flutter mechanism is investigated with equivalent frequency-domain modes. A way to increase the flutter speeds by introducing chordwise-bending flexibility near the fin trailing edge is introduced and demonstrated.