Influence of Volume of Air on the Muzzle Velocity of the Projectile

In the present study, the ogival-nosed hardened steel projectile having a mass of 0.4 kg, diameter of 19 mm, calibre radius head (CRH) of 3, and length of 200 mm was used to obtain their muzzle velocity with respect to their corresponding air pressure. The two pressure vessels with varying storage capacities (20 and 90 liters) connected with the same actuator (having an opening diameter of 25.4 mm) were used to describe their influence on the muzzle velocity of the projectile. Also, the two actuators with varying opening diameters (25.4 and 50.8 mm) connected with the same pressure vessel (having a storage capacity of 90 liter) were considered to describe the influence of releasing a large volume of air on the muzzle velocity of the projectile. Based on these variations, three testing configurations such as (1) the pressure vessel with a storage capacity of 20 liter connected with the actuator having an opening diameter of 25.4 mm will be described as Case 1, (2) the actuators with an opening diameter of 25.4 connected with the pressure vessel having a storage capacity of 90 liter will be described as Case 2, and (3) the actuators with an opening diameter of 50.8 connected with the pressure vessel having a storage capacity of 90 liter will be described as Case 3, were made. Based on the experimental results, the muzzle velocities of the projectile obtained for Case 3 were found to be higher than that obtained for Case 2 at pressures varying from 10 to 55 kg/cm2. Also, the actuator having a double opening diameter (50.8 mm) was responsible for increasing the muzzle velocity of the projectile to a maximum of 58% due to releasing a larger volume of air than that for Case 2. The muzzle velocity obtained for Case 2 was equal to that obtained for Case 1 at low pressure (10 kg/cm2). However, the muzzle velocity obtained for Case 2 was higher than that obtained for Case 1 at pressures varying from 15 to 55 kg/cm2 and increased to a maximum of 6%, describing the influence of using the pressure vessel having 4.5 times higher storage capacity than that used for Case 1. Hence, using the actuator with a large opening diameter was more effective for increasing the muzzle velocity of the projectile than the pressure vessel with a large storage capacity.