Royal Ordnance L7

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Royal Ordnance L7 in the Swiss Military Museum Full

The Royal Ordnance L7 is a British chariot cannon . The design and performances of the weapon proved so successful that it was used in many Western models of tanks. The Royal Ordnance Factories developed the weapon to replace the obsolete 20 pounder cannon. It is one of the most widely used cannons in vehicles in the world. A total of around 20,000 copies were made.

Development history

cut pipe

The 1956 popular uprising in Hungary gave the impetus for the development of a new cannon for main battle tanks . During the fighting with the Soviet troops, the insurgents managed to drive a captured T-54 onto the grounds of the British embassy. There it could be examined by British experts. Investigations revealed that the cannon used in the Centurion Mk 3 at the time was unable to penetrate the armor of the new Soviet tank. At the same time, the T-54's 100-mm D-10T cannon showed excellent performances. Based on this knowledge, it was decided to develop a 105 mm cannon that could penetrate the strong front armor of the T-54 and be mounted in the Centurion's cradle in order to subject the tanks of this generation still in service to a combat value increase at low cost .

The first tank fitted with the cannon in 1959 was the Centurion Mk 5. In the years that followed, many western tanks received the cannon, including the Leopard 1 and the M60 . Even during the Second Gulf War , M60s of the United States Marine Corps were able to destroy several Iraqi T-72 tanks .

The L7 is now obsolete due to the further development of weapon technology in the direction of the smooth barrel cannon . In most modern western main battle tanks, it has been replaced by Rheinmetall 's 120mm smoothbore gun , which was originally developed for the Leopard 2 . This replaced the L7 as part of combat value increases like the M1A1 Abrams or was preferred for new projects.

technology

functionality

The L7 is a rifled cannon with a length of 52 calibers. The lock is a semi-automatic cross wedge lock that opens to the right. The cartridge is ignited electrically. The return of the weapon after the shot is about 290 mm. The cannon is equipped with a smoke evacuator and, on most tanks, is encased in a thermal protective sleeve. The use of the weapon on ships and in coastal defense systems was planned, but was not implemented.

ammunition

The L7A3 on a Leopard 1 A1A4
The ammunition types APDS, HEAT and the crush head bullet HESH / HEP
  • APDS ( A rmour- P iercing D iscarding S abot): A subcaliber kinetic energy projectile, which acts by its kinetic energy. A penetrator made of depleted uranium (as in the US Army) or sintered tungsten carbide (for example in the German Armed Forces) is used, the high specific weight of which increases the energy per area again compared to steel. The sabot (now made from carbon fiber reinforced plastic )seals the projectile, which is smaller in diameter,from the barrel and detaches itself after exiting the barrel due to the increased air resistance. Sabotage is also unintentionally projectiles and creates a danger zone up to 200 m from the muzzle.
  • APERS-T ( A nti Pers onell - T racer): A fragmentation projectile for fighting infantry.
  • APFSDS ( A rmour P iercing F in S tabilized D iscarding S abot): Similar to the APDS projectile, however, the penetrator is longer and is stabilized by a tail unit instead of by twisting.
  • HE ( H igh E xplosive): An explosive projectile with a fragmentation effect.
  • HEAT ( H igh E xplosive A nti T ank): A hollow charge projectile against enemy armored vehicles. Due to the gas hammer effect, unlike APDS and APFSDS, it can also be used against unarmored vehicles, building structures and infantry.
  • HESH ( H igh E xplosive S quash H ead), also known as HEP - (high explosive plastic): An explosive projectile that does not necessarily penetrate the armor of enemy battle tanks, but rather is supposed to trigger shock waves in it, which shatter fragments on the inside and which Can injure or kill crew or destroy important components. The function is promoted by the twist (the explosive material expands between impact and ignition). Weak armor is completely penetrated. Due to the powerful gas hammer effect, HESH is also often used against unarmored vehicles, building structures and infantry. Hits in the chassis of a battle tank (for example on a wheel) immobilize it reliably. The projectile wall must be kept thin to function, so that the projectile can withstand lower accelerations in the barrel and therefore only achieve relatively low muzzle speeds (750 to 900 m / s).
  • Phosphorus ammunition : Incendiary ammunition for use against infantry, but also to obscure enemies by impacting close to their position Thermal imaging cameras are also hampered by the heat of the burning phosphor. The heat radiation and the weak visible light can, however, also be used as background lighting to improve your own night vision options.

Technical specifications

designation Royal Ordnance 105mm L7 tank gun
Caliber: 105 mm
Length: 5588 mm
Weight: 1287 kg
Cadence: 10 rounds / minute
effective range: 1800 m with APDS
Lifespan: 200 rounds with APDS

variants

  • L7A1
The standard variant.
  • L7A3
The variant of the Bundeswehr for use on the Leopard 1. The top of the base was bevelled so that the weapon does not collide with the tower roof with a minimal tube elevation of −9 °.
  • L74
Swedish variant with 61 caliber lengths for use on the Stridsvagn 103 .
  • M68
US version for the M60 with the designation M68. The lock was replaced by a drop wedge lock and the design of the smoke evacuator differed from the original. This variant was also used on the M1 Abrams . The version M68A1E4 is used in the M1128 Stryker MGS .
  • KM68A1
Korean production of the M68 under license. It was used in Korean versions of the M48 .
  • Type 79/81/83 / 83A
Chinese copies of the L7.
  • FM K.4 Modelo 1L
Argentinian licensed productions for use on the Tanque Argentino Mediano .

commitment

Bunkered anti-tank position with L7

literature

  • Steven Zaloga : T-54 and T-55 Main Battle Tanks 1944-2004. Osprey Publishing, ISBN 978-1-84176-792-5 .
  • Surrey Coulsdon: Jane's Armor and Artillery Upgrades 1995–1996. Jane`s Information Group Inc.

Web links

Commons : Royal Ordnance L7  - collection of pictures, videos and audio files
  • Stefan Kotsch: 105 mm L7. The British 105 mm L7 tank gun. In: Main battle tanks in detail. Retrieved December 11, 2014 .
  • Stefan Kotsch: 105 mm L7A. The ammunition for the 105 mm L7A cannon. In: Main battle tanks in detail. Retrieved December 11, 2014 .

Individual evidence

  1. ↑ a b c Surrey Coulsdon: Jane's Armor and Artillery Upgrades 1995–1996. P. 43.
  2. ↑ Steven Zaloga: T-54 and T-55 Main Battle Tanks 1944-2004. P. 39.