22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-5.6.2

MATHEMATICAL MODELING FOR STUDYING THE CONDITIONS OF AIR AMMUNITION WARFARE

L.Turchak, A. Belotserkovski, M. Kanevski, N. Baranov
Computing Centre of Russian Academy of Sciences, Russia

Keywords: store separation, air ammunition warfare, aerodynamic interference

Experience of ammunition warfare has shown that a store at the start leg of its flight toward a target when relative velocity of the store with respect to the aircraft is small and the store moves inside the compartment or near the aircraft, the store experiences additional aerodynamic forces and moments due to interference with the aircraft. The magnitude of these forces (depending on different conditions) can exceed 3 to 5 times its own weight for small caliber stores (air guided missiles or unguided rockets) and can amount to as much as 80% of the own weight for large caliber stores (air bombs, heavy air-to-surface or air-to-air guided missiles). Interaction of • store and disturbed airflow near the aircraft yields significant oscillations of the store. This can lead to the following effects: store reentry into a compartment; store-to-store collision; store-toaircraft collision; gas dynamics stability loss of the aircraft power plant due to the store jet engine entering into the aircraft air intake; thermo-damage of the aircraft surface due to the store jet engine action; deterioration of unguided rocket accuracy performance; violation of conditions for normal functioning of the store control and guidance systems, for example, crossing of the admissible limits for load factors, angular rates, target aspects, etc. All these phenomena have occurred in practice, and thus reinforces the inportanse of improving air ammunition safety and performance by modeling its start regimes. Most of the known approaches to store separation simulation can be divided into four large groups: computer simulation; simulation in wind tunnels; combined methods based on computer simulation of store dynamics using experimental information on aerodynamic disturbances near the aircraft; and flight experiment. Since store separation conditions depend on various factors (including the aircraft maneuver type, ACC flight regime, store location types, store separation process, etc.), experimental investigation of store separation trajectories in the aircraft warfare operating range is very bulky, expensive, and sometimes dangerous. Therefore, in Russia and in other countries, mathematical methods of store separation simulation are being devised intensively. Most approaches to mathematical simulation of store separation are based mainly on steady aerodynamic models and consider only unilateral aerodynamic influence of the aircraft on stores. For this reason they cannot be used for store separation process investigation in the wide range of aircraft warfare. For solution of the problem the authors have developed store separation calculation methods for internal and external placement of stores. These methods are adapted to conventional and new (from the upper side of wings and the rear hemisphere of the aircraft) procedures of store separation and are based on the synthesis of the following theories: unsteady dynamics, aerodynamics, and aeroacoustics of the aircraft (calculation of aerodynamic disturbances); unsteady aerodynamics of a store; unsteady aerodynamic interaction of a store with nonhomogeneous airfield disturbed by ACC; and store ballistics.

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