Smooth barrel cannon
In weapons technology, a smooth barrel cannon is a cannon with a smooth barrel barrel . Smooth barrel guns are the original form of firearms before they were replaced by guns with rifled barrels or barrels due to their higher precision . The further development of weapon technology in the middle of the 20th century led to the development of modern smooth barrel cannons, which are based on modified projectile technology. Since the bullet is not placed in the stabilizing twist due to the lack of fields and pulls in the barrel , it is stabilized by fins or fins. Smoothbore cannons are the standard armament for modern battle tanks worldwide.
History and Development
The history of the development of smooth-barreled weapons ranges from the early fire pots to muskets to the pea pistol and field cannons , mortars and carronades to modern high-performance guns . Up until the middle of the 19th century, all cannons were smooth-barreled cannons, as they fired round spheres which, given their short range, had few problems with flight stabilization. During the Second World War , smooth-barreled cannons were tested again, because higher projectile speeds can be achieved with them, which in turn leads to higher penetration performance.
In 1955, the 100 mm anti-tank gun MT-12 was the first modern smoothbore gun in the Soviet Union. At the end of the 1950s, the 115 mm smoothbore cannon U-5TS followed in the T-62 battle tank ; it was thus the first modern tank smoothbore cannon. Once in the " western world " - especially in the army - doubts about the performance of the 105-mm gun mid-1960s Royal Ordnance L7 came up against the new tanks the Soviet Union in 1965 during the development of the Leopard 2 by Rheinmetall started a completely new development, which led to the 120 mm smoothbore cannon Rh 120 within a development period of ten years . A tri-national comparative shooting between the 105 and 120 mm cannons from American and British production and the Rh 120 showed the superiority of the new development. Smoothbore cannons have thus been the standard armament of modern battle tanks since the 1960s ("Eastern Bloc") and 1980s (NATO).
These systems will also be further developed in the future. The development of the " New Panzerkanone 140 " in 140 mm caliber at Rheinmetall was discontinued because the installation would have resulted in the costly replacement of the armored turrets. This was compensated for by developing the L / 55 variant of the 120 mm smoothbore cannon, which can penetrate any existing armor with modern types of ammunition. Further developments are currently - in addition to a further increase in performance - a reduction in recoil so that large-caliber smooth-barreled cannons can be installed in lighter carrier vehicles (for example the LLR L / 47 ).
Background and technology
In the case of a gun barrel with rifles, the inside diameter of the barrel is slightly smaller than the guide band or, in the case of smaller calibers, the outside diameter of the projectile. This "oversized caliber" presses it into the rifles and is set in a twisting motion by them. As a result, however, there are high frictional forces which reduce the acceleration of the projectile by the propellant charge . In addition, the sealing of the propellant gases against fields and trains is less, which limits the effectively achievable pressure.
This restriction is reduced with a smooth-barreled cannon, since the propellant gases are sealed against the barrel by a sabot . With the same propellant charge, much higher muzzle velocities can be achieved and extreme gas pressures can be achieved (for example with the Rh 120 L / 44 around 7100 bar ). The higher muzzle velocity and the resulting greater kinetic energy ensure a significantly higher penetration power in the case of mass bullets . Another advantage of the smoothbore gun is that it is much easier to clean.
In the case of shaped charge projectiles (HEAT - High Explosive Anti Tank), the lack of twist is a further advantage, since the rotation of the projectile impairs the Munroe effect and leads to an expansion of the "shaped charge spike". Other types of ammunition such as smoke bodies or grapeshot can also be fired.
Sabot shells
A smoothbore cannon does not have fields and trains to give the projectile a stable trajectory. Therefore, these are wing stabilized, that is, they have a tail unit. The projectile itself is a sub-caliber, arrow-like projectile and is guided in the barrel by a sabot when it is fired, which falls off shortly after leaving the barrel due to the high air resistance.
Sharp bullets have a fin tail, while the Bundeswehr's training ammunition is equipped with a perforated cone tail, which reduces the safety area to a fraction. This means that you can also shoot on smaller practice areas. However, the flight characteristics are only comparable with those of live ammunition for the first few kilometers.
distribution
Due to political and economic ties, there was a technology transfer to different countries. The USA has been using the M256 , a license-produced Rh-120, in the M1 Abrams since 1984 . Israel developed its own smoothbore cannon for the Merkava , which is compatible with the 120 mm NATO ammunition . The French Leclerc is also equipped with a smoothbore cannon and was delivered to Saudi Arabia and the United Arab Emirates.
In the states of the former Warsaw Pact and the successor states of the Soviet Union, smoothbore cannons are still being developed and used. The U-5TS was followed by the D-81 T with a caliber of 125 mm. It was installed in large numbers in the T-72 . The successor models T-80 and T-90 use the type D-81TM and further developments. By exporting these tanks to India, for example, and copies by China for the Type 99 and others, they are now widely used.
