The Chrysler Hyge impact simulator permits full-scale laboratory simulation of the deceleration experienced by an automobile passenger compartment during impact. The need to duplicate a great variety of deceleration pulse shapes necessitates a large number of operating parameters. Unfortunately, this large number of parameters precludes easy determination of the relationships between parameter selections and desired pulse shapes.This paper describes the development of a mathematical model and digital computer program used by the Chrysler Engineering Office to predict the response of the impact simulator for a given set of parameters. The principle elements of the model deal with unsteady compressible gas flow and the effect of the resulting forces on the sled motion. The modeling of the metering pin is of particular importance, since the characteristic shape of the acceleration pulse is limited by the pin contour.With the aid of this model it is possible to specify the complete set of operating parameters needed to simulate a desired pulse shape. This eliminates the need for costly, time-consuming, cut-and-try experimentation.