Abstract: In the firing accuracy and dispersion test of rapid-fire weapon, several projectiles fired from a barrel may pass through a light-screen simultaneously. On this condition, some photoelectric target measurement systems cannot measure the exterior ballistic parameters of these projectiles. A qualitative analysis of this phenomenon should be undertaken to obtain the measured values for choosing a reasonable photoelectric target measurement system. The reduced mathematics description of the phenomenon is presented. The two mathematical models for the probability passing through the screen are established, respectively, based on certain and uncertain velocities of the flying projectiles. The change rule of the passing probability with projectiles’ flight distance is deduced according to the optimization mathematical model, and the three important parameters, such as critical distance involved in the passing probability, maximum probability and passing probability at direct fire distance. Experiments show that the reasonably chosen photoelectric target measurement system can avoid the measurement data being influenced by the projectiles passing through a screen simultaneously. Key

Key words: rapid-fireweapon, projectilevelocitydispersion, firingaccuracyanddispersion, exteriorballistictest, photoelectrictargetmeasurementsystem