Separation modeling of the internal air-launch rocket from a cargo aircraft

Internal air-launch Rocket enables timely deploying of small satellites specially designed for urgent missions. The numerical modelling of the dynamics of thematic-body system consisting of the aircraft, the rocket, the cable and the parachute disturbed by aerodynamic effects. This article mainly studies the modeling of the air launch rocket separating from a cargo aircraft. Based on the definition of a rational frame, the complete nonlinear force and moment equations are established using the Newton's second law and the Euler angle relation of rigid body. Lumped mass model and the Gauss principle of least constraint are used to describe the flexible model of cable and parachute. Thereafter the effects of aerodynamics and the flexible cable are investigated. Simulations show that the stability of the aircraft can affect the safety of the rocket separation; therefore, a special aircraft control strategy should be developed to guarantee the required system performances.