Dynamics modeling and simulation of small flexible wing aircraft

Small flexible wing aircraft (FWA) is a kind of flexible aircraft which uses distributed actuators to deform the wing so as to get a better aerodynamic shape and generate control forces and torques. The elastic vibration of the wing will have a great influence on rigid-body degrees of freedom (DoF) for the aircraft. The 6-DoF model of flight dynamics, which is under the traditional rigid-body assumption, cannot describe coupling effects of the rigid-body and elastic degrees of freedom. To solve this problem, the aircraft needs to be taken as an elastomer free in space to establish its dynamic model, which is studied based on the second class Lagrange's equation in this paper. By this modeling method, complete kinetic equations of FWA are derived under the mean axes condition, and the unsteady aerodynamic is included in the equations. Unsteady aerodynamic is calculated by two-dimensional Theodorsen's theory. And strip theory assumption is used to simplify the calculation. To analyze the influence of the unsteady aerodynamic on the structure vibration of the wing, the time-domain response characteristics of wing structure with and without unsteady aerodynamic are compared in this paper by numerical calculation. And the results show that the unsteady aerodynamic will cause great damping effect.