We know that because the density of water is nearly 800 times higher than that of air, the resistance of bullets flying in water is much greater than that in air. Therefore, the range and lethality of the bullets designed to shoot in the air medium in the water are extremely limited.
There was a physicist named Andreas Val who did a very dangerous experiment to prove this. He fixed an assault rifle in the swimming pool, and then stood in the water not far from the muzzle of the gun. He used a rope connected with the trigger to control the rifle and fired at him. Val was only wearing a swimsuit, not a bullet proof vest.
We can see the trajectory of the bullet in the water, which quickly loses stability and stalls.
Of course, this experiment is carried out after several simulation tests and preparations for safety assistance. It can be clearly seen that after the traditional bullets are fired from the gun bore, they lose their lethality within less than two meters and fall to the bottom of the pool.
The bullet fell to the bottom of the pool soon after it was fired.
So even though the ordinary rifle can shoot normally in the water, the bullets fired are almost harmless, let alone use it to deal with enemy divers or vehicles. Without rifles, divers can only fight with weapons such as daggers or spears, which is obviously not enough. In order to solve this problem, Russia, Germany and other countries have developed special underwater guns.
One of the most famous is the Russian APS underwater assault rifle. This gun was developed by the Soviet Union in the early 1970s to improve the underwater shooting distance of frogman, and was used to replace the spp-1 underwater pistol. The gun began to equip the frogman troops of the Soviet army in 1975 and is still in service in the special forces of the Russian navy.
APS underwater assault rifle and MPs arrow shaped projectile, APS adopts 26 magazines, with a total weight of about 3.4kg.
APS is actually improved from AK rifle, the biggest feature is the use of MPS underwater special archer. MPs consists of a 5.45 u00d7 39 shell with an enlarged bottleneck and an arrow shaped warhead 120 mm long and 20.2 g in weight.
This kind of special warhead can maintain good motion stability in the water, and the effective range is 30 meters, 20 meters and 10 meters respectively at 5 meters, 20 meters and 40 meters. The gun has no rifling. Theoretically, it can shoot on the water, but its barrel life is only about 200 rounds, and underwater shooting can reach 2000 rounds.
This kind of rifle has a good killing power in the water. It can deal with the thickened diving suit, helmet and other underwater equipment of frogman, but its disadvantages are also very obvious.
Russias spp-1m underwater pistol is similar to a catapult gun in structure. Like APS, it also uses an arrow shaped bullet with a warhead weight of 12.8g and can hold four bullets at a time.
In order to accommodate the arrow shaped projectile, only one large flat magazine can be set up, which is heavier after being filled with water, making it inconvenient for the gunman to move and aim. The muzzle velocity of the gun on the water surface is 365 M / s, and the effective range of the paper is 100 m, but it is said that the actual effective range is not more than 50 m. In short, once it enters the water to fight, it basically loses its place of use and becomes the death weight of soldiers.
Therefore, Russian frogmen prefer to use spp-1m pistol and regular AK rifle. The former is light and convenient for underwater combat, while the latter is used on the water surface.
Almost the same time as APS, it was equipped with the German developed hkp11 underwater pistol, which was different from the Russian made underwater projectile which was improved by using the traditional shell and arrow shaped warhead. P11 uses a 7.62mm long arrow ammunition, which does not have the shell of conventional bullets. Instead, it seals the propellant and warhead directly in the barrel, and sends electric shock through two batteries installed in the handle.
When the P11 pistol is disassembled, it can be seen that there are five integral chambers, the handle of the live firing device and the warhead. (picture above) integrated chamber, five barrels can be seen, on which there are rubber sleeves for sealing. (below)
The ammunition of P11 is 117 mm in length, 31 g in weight, and its underwater range is 10-15 meters. Because of the heavier warhead, it has greater killing power than the Russian spp-1m underwater hand gun, but the whole gun can only be sent back to the manufacturer for refilling after it is finished, and the spp-1m can be refilled by itself.
Most of the above ammunition use streamline warhead to weaken the influence of water resistance on shooting, and the shooting ability above the water surface is weak. Cav-x, on the other hand, has made a more complex treatment of warheads, so as to use the principle of supercavitation to greatly improve the range and lethality, which can be used in a variety of water or underwater environments.
Speaking of the supercavitation technology, we have to mention the va-111 type storm supercavitation torpedo in Russia. It uses a rocket engine as the source of propulsion power, which is naturally faster than the traditional propeller power.
Russian storm torpedo, the figure below is the cavitation emitter of the torpedo head. Its more like a missile than a traditional torpedo.
But in order to solve the influence of the resistance in water on the speed, the head of storm torpedo can eject rocket gas, instantly turning the water in front of the torpedo into water vapor, generating cavitation. As the torpedo moves forward, the thin layer containing water vapor will wrap the whole torpedo body or be the same length as the torpedo body. This process is called supercavitation, which can greatly reduce the resistance of navigation in water.
Supercavitation technology enables Stormwind torpedoes to sail at speeds of up to 200 knots (370 km / h), which are designed to engage enemy nuclear submarines. With accurate guidance, no submarine can escape its pursuit.
As mentioned above, storm torpedoes use high temperature rocket gas to create a supercavitation environment. This is almost impossible to achieve on 12.7, 7.62 or even 5.56 mm caliber bullets. Even if it can be achieved technically, as a special bullet whose output is far less than that of conventional bullets, it is not cost-effective.
According to DSGs promotional materials, cav-x is a special warhead shape, so that it can form supercavitation bubbles when flying in water. In theory, the special structure can reduce the pressure of water on the warhead surface to below the saturated vapor pressure. At this time, the water will vaporize and form cavitation, which may further form the supercavitation of the warhead.
DSGs 7.62, 5.56 and 12.7mm supercavitation ammunition are displayed in kind with special warhead configuration.
In DSGs penetrating video, the testers first loaded a common bullet into a AR15 rifle and fired a trajectory test gel. The impact of ordinary ammunition is very strong, but only penetrates a gel, advancing about 0.5 meters. The super cavitation ammunition penetrated 10 pieces of gel, with a thickness of about 4 meters, and the penetration power increased significantly.
In another promotional video, testers fired supercavitation bullets at targets in the water from the edge of the pool for two purposes. The first is to confirm whether the warhead will jump when shooting at the water surface, and the second is to test the underwater penetration.
Supercavitation ammunition can not only deal with frogman, but also be used to detonate mines with small depth and drive away small submarines. According to foreign media reports, the accuracy is not low, and the distance away from the target is no more than 3cm at a distance of about 45m.
Supercavitation projectile surface shooting experiment. This kind of bullet does not need special modified firearms, and can be directly used in active ar series rifles and M2 series machine guns. This means that if the U.S. Army trains this kind of bullets, amphibious special warfare forces only need to carry conventional rifles, and do not need to carry another underwater weapon, avoiding the problem that the effectiveness of APS and other active underwater guns in the water shooting environment is greatly reduced, as an effective supplement to the combat effectiveness of special forces. Source: Tan Bing, Netease editor in charge: Wang xu_b12062
This kind of bullet does not need special modified firearms, and can be directly used in active ar series rifles and M2 series machine guns. This means that if the U.S. Army trains this kind of bullets, amphibious special warfare forces only need to carry conventional rifles, and do not need to carry another underwater weapon, avoiding the problem that the effectiveness of APS and other active underwater guns in the water shooting environment is greatly reduced, as an effective supplement to the combat effectiveness of special forces.