Investigation and comparison of performance of some air gun projectiles with nose shape modifications

摘要

Shooting accuracy of air gun projectiles is very important in sport tournaments and has always been questioned by enthusiasts. For this purpose, the performance of four samples of air gun projectiles (pellets) with various shapes and calibers of 4.5, 5.5 and 6.35?mm was studied in this article. The projectiles were four basic shapes: flat nose, sharp nose, round nose and spherical. After these projectiles were modeled geometrically, the three-dimensional compressible turbulent Navier–Stokes equations and dynamic equations of the projectiles’ motion were solved in a coupled form and in a moving computational grid. The computed results describe the trajectory, velocity variations and the altitude loss of the projectiles with time and location. Comparisons indicate that the round nose projectile had the best performance at long distances compared to the other samples. The flat nose projectile exhibited great performance at short distances, but behaved weakly at long distances. In addition, the effect of nose shape on the performance of the sharp and round nose projectiles was studied and the optimum nose shapes were identified.