Modelling and analysis of a hydropneumatic recoil mechanism in artillery

In this study, the recoil movement of heavy weapons with hydropneumatic recoil mechanism is modeled. The primary purpose of the study is to obtain the equation of motion of the recoiling parts in the weapon systems. For this purpose, the forces acting on the recoiling parts were determined, and the effects of each force were examined. Breech force is calculated via LeDuc equations for in bore period and verified by comparing with experimental studies from literature for a typical 105 mm howitzer and from MKEK for a new generation lighter 105 mm weapon system. Additionally, velocity of projectile in barrel is calculated from the model and compared with test data. Breech force which is generated during the discharge of the remaining gases after the projectile leaves the barrel is also calculated and total breech force is obtained. Then, net retarding force that consists of friction, hydraulic brake and recuperator forces are calculated. After determining breech and net retarding forces, the equation of motion is obtained, and solved via MATLAB. Recoil distance, velocity and acceleration of recoiling parts are calculated and effects of firing angle, weight of recoiling parts, orifice discharge coefficient, muzzle brake efficiency are investigated. Comparisons show that model results are compatible with test data and the differences between them is less than three percent. Additionally, it is deduced from this study that if firing angle and orifice discharge coefficient increase, maximum recoil displacement, maximum velocity, and maximum acceleration values of recoiling parts increase. When orifice discharge coefficient is increased by 20 percent, maximum recoil displacement, velocity, and acceleration of recoiling parts are increased from 1109 mm to 1220 mm, from 45.2 m/s to 49.7 m/s and from 21.6 m/s2 to 23.7 m/s2, respectively. In addition, maximum recoil displacement, maximum velocity, and maximum acceleration values of recoiling parts decrease if weight of recoiling parts and muzzle brake efficiency increase. When weight of recoiling parts is increased by 20 percent, maximum recoil displacement, velocity and acceleration of recoiling parts are decreased from 1109 mm to 921 mm, from 45.2 m/s to 37.5 m/s and from 21.6 m/s2 to 17.9 m/s2, respectively. Besides, as the muzzle brake efficiency increases from 1 to 1.5, maximum recoil displacement and velocity of recoiling parts decreased from 1109 mm to 1075 mm, 45.2 m/s to 43.8 m/s, respectively.