Influence of Aircraft Flow Field on the Longitudinal Stability of a Missile

Abstract

An air-to-air missile launched from a fighter aircraft needs to be stable at launch to enable safe separation from the aircraft, and less stable in the terminal phase of its flight to become highly maneuverable to intercept the targets. A study has been carried out to estimate the effect of the aircraft flow field on the longitudinal stability of the missile using an in-house developed 3-D grid-free Euler solver. Initially, the missiles are placed in the captive location in the launcher of the aircraft. One of the missiles is then moved to various pre-determined locations ahead of the wing of the aircraft, keeping the other missile at the captive location. The centre of pressure and stability margin of the missile is determined at these locations. It is observed that the presence of aircraft has a substantial effect on the longitudinal stability of the missile. The centre of pressure of the missile is seen to move aft as it leaves the launcher. As the missile moves, the centre of pressure reaches a maximum aft position and then moves forward till it reaches a position where the missile is free from the influence of the aircraft. It is observed that as the missile moves away from the region of strong influence of the aircraft, its aerodynamic characteristics approach asymptotically to that of the isolated missile.

Defence Science Journal, 2013, 63(3), pp.242-248, DOI:http://dx.doi.org/10.14429/dsj.63.2099