Numerical simulation of missile air-launching process under rail slideway constraints

Computational fluid dynamics and rigid body dynamics models are solved in a loosely coupled way to simulate a missile launched from an aircraft by rail, the motions consist of three phases, which correspond to two or multi- hanger phase, single hanger phase and free motion phase. In order to simulate the motion of missiles subjected to single hanger constraint, the constrained dynamics equations are derivated from six degree of freedom motion equations, the model is verified by simulating free rotation of rigid body (Euler gyro) and procession of rotational rigid body(Lagrange gyro), which shows good agreement with the theoretical solutions. After that, the launching process of a missile from an aircraft is numerically simulated, in which constrained and non-constrained rigid-body dynamics models are switched corresponding to hanger's position. By numerical simulation, trajectories and attitudes profile of the missile are obtained. The results show that the missile is impacted by lateral wash flows at moderate angles of attack, resulting in large lateral force and yawing moment, causing the missile to roll rapidly and produce missile-frame interference further. In the phase of single hanger constraint, the missile tends to pitch due to normal aerodynamic force, gravity, normal overload and so on, which may lead to interference with rail launcher on harsh conditions.