EXPERIMENTAL RESEARCH ON A NEW METHOD OF UNDERWATER LAUNCH WITH HIGH EFFICIENCY AND LOW RESISTANCE

A new high-efficiency and low-resistance launching method for underwater gun is proposed. That is the underwater gas-curtain launch. By introducing part of the gas inside the chamber to the front of projectile to drive water inside the barrel out, a low-resistance gas passage is provided for the projectile motion in the bore. So, the problems of poor safety and low muzzle velocity of the traditional fully submerged gun is solved, and a better interior ballistics performance than the fully-submerged launch can be realized. The experiment is carried out using three underwater launch methods, namely sealed launch (with complex structure, and it is difficult to adapt to underwater shooting environment), fully-submerged launch and gas-curtain launch. The experimental results show that the muzzle velocity is 228.2 m/s while the maximum chamber pressure is 25.7 MPa of the sealed launch. However, the muzzle velocity is 172.8 m/s while the maximum chamber pressure is up to 116.0 MPa of the fully-submerged launch. While the new underwater high-efficiency and low-resistance launching method is adopted, the maximum chamber pressure is only 41.8 MPa and the muzzle velocity is 177.5 m/s. It can be seen that the maximum chamber pressure is reduced by about 64% under the same muzzle velocity, and the significant drag reduction effect of gas-curtain launch greatly improves the interior ballistics performance when compared with the existing fully-submerged launch. It is clear that, the maximum chamber pressure and muzzle velocity of the fully-submerged launch are 451.4% and 75.7% of the sealed launch, while the maximum chamber pressure and muzzle velocity of the gas-curtain launch are 162.6% and 77.8% of the sealed launch. Through the shooting experiment, the drag reduction effect of the newly proposed gas-curtain launch and the improvement effect on the interior ballistics performance are revealed.