Predicting the Impact Point of a Falling Body, Subject to Drag, in Real-Time Simulation

Dr Stephen Cull

Centre for Systems Simulation, QinetiQ, Bedford

The Real Time All Vehicle Simulator (RTAVS) harness is a tool used by QinetiQ, predominantly for aircraft simulation. Within this harness there is a need to calculate, in real-time, the impact point of air-to-ground munitions dropped from aircraft flying at altitudes of up to 30,000 feet. The falling munitions are subject to drag during its flight. The drag force is dependant on the air pressure and density which vary with altitude. This makes the equation of motion for the falling munitions non-linear. Currently the impact point is predicted by extrapolating the equation of motion in discrete time steps. This method is rather crude and we would like to know whether there is an alternative. The alternative will have to work within the same constraints of the existing method. That is, any calculations will have to complete in one 50Hz harness cycle and have no detrimental effect on other processes being performed in the same cycle.