Dynamic modeling of deflectable nose missiles

Deflectable nose control is a novel missile control configuration and its accurate dynamic modeling is essential for missile performance, stability and control analysis. In this article, the governing equations of motion are derived for the deflectable nose missile based on multi-body Kane formulation. First, three reference frames are introduced and eight generalized speeds are chosen to express the motion states of the missile body and nose. Kinematic equations are then obtained, from which generalized active forces and generalized inertia forces can be written where the moments between the missile body and nose are treated as active moments rather than ideal constraints. Finally, eight scalar dynamic equations can be obtained. It is shown that Kane's method makes the modeling more simple as compared with the Newton-Euler method. Simulation analysis based on the accurate dynamic equations is carried out to evaluate the simplified model on the assumption that the mass center and deflection center of the missile nose fall on the same point. The simulation results indicate that the simplified model will lead to a large error in the dynamic response of the missile when the missile nose deflects slowly.