Determination of the Shot Energy Characteristics of the Pneumatic Gun by Means of High Speed Imaging Method

Abstract

The article presents the method for the determination of energy characteristics of the pneumatic cannon by means of high speed imaging. The gun tested is a device enabling bird collision endurance tests to be conducted for the structural element of aircrafts. In the tested 250 [m system, the projectiles were thrown in the plastic sabot damaged in the muzzle of the gun. The tests were conducted in the speed ranging between 100 300 m/s for 0.9 and 3.6 [k projectiles. The objective of the tests was to determine the characteristics of the projectile outlet velocity in the feed pressure function. The measurement stand was equipped with the Phantom V310 high speed camera The speed measurement was conducted with the use of the digital image analysis in which commercial TEMA Motion software was used. Results were corrected so that the parallax error could be eliminated. Because of the cylindrical shape of the projectile, the parallax error for the front at the back of the projectile varied, which required two correction coefficients to be applied. The speed was calculated by the averaging of the results for the front and the back of the projectile. For the recordings, in which the remaining of the sabot prevented the accurate arrangement of measurement points, a simplified speed measurement method was used. Measurement uncertainty sources are also described (shift of the projectile at the time of the exposure, measurement point positioning error). The influence of the parallax error on the measurement result and the cannon energy characteristics obtained are presented. The obtained characteristics enable proper selection of feed pressure allowing for the procurement of the outlet velocity suitable for the tests conducted.