Flight dynamics modeling and stability analysis of a tube-launched tandem wing aerial vehicle during the deploying process

Abstract

During the subsequent deploying process after the launch, the vehicle experiences dramatic changes in geometry as well as aerodynamics, which cannot be ignored for the flight stability of the aircraft. The investigation on the flight dynamics modeling and stability analysis during the unsteady deploying process is of great significance for the flight control system design and the launch system design. The nonlinear multibody dynamic model of the vehicle, which mainly consists of the airframe and four wings, is established through the Newton–Euler method. Meanwhile, the unsteady vortex lattice method (VLM), which is suitable for tandem wing aircraft and combined with the viscosity effect in light of the strip theory, is proposed to calculate the aerodynamic loads of the vehicle during the deploying process. A series of simulations about the motion of the vehicle after the launch are calculated to analyze the effects of various parameters, including the deploying forms, the start-up time of the power system along with the launching parameters, on the stability of the aerial vehicle in the deployment process. As results indicated, a small difference in the deploying rates of wings and larger deploying rates of wings on the same side are beneficial to the stability of the vehicle during the deploying process. Additionally, it is advantageous to the pitching stability but not the lateral stability of the vehicle when the power system is started earlier. Besides, the attitude control strategy of the vehicle can be formulated in advance by analyzing the attitude of the vehicle with different launch parameters at the launching moment.