|Place of origin||United Kingdom|
|Used by||See users|
|Designer||Armament Development Establishment|
|Manufacturer||Royal Small Arms Factory|
|Mass||196 kg (432 lb) with 200 rounds|
|Length||1,590-1,639 mm (5 ft 2.6 in-5 ft 4.5 in)|
|Barrel length||1,080 mm (3 ft 7 in)|
|Action||gas operated revolver|
|Rate of fire||1,200-1,700 rpm|
|Muzzle velocity||795 m/s (2,610 ft/s)|
The Royal Small Arms Factory ADEN cannon, (ADEN being an acronym for "Armament Development, Enfield", is a 30 mm revolver cannon used on many military aircraft, particularly those of the British Royal Air Force and Fleet Air Arm. Developed post-World War II primarily to meet British Air Ministry's requirement for increased lethality in aircraft armament, the cannon was fired electrically and is fully automatic once it is loaded.
During World War II, the German firm Mauser began development of a radically new 20 mm autocannon using a motorised firing mechanism in order to improve the rate of fire. The weapon got the preliminary designation Mauser MG 213 and by the late-war period the design was beginning to mature. However the presence of large heavy bombers like the Boeing B-17 Flying Fortress and Avro Lancaster led to the need of up-arming Luftwaffe fighter aircraft with heavier cannons. Mauser responded to this by adapting the MG 213 to fire the 30 mm rounds from the MK 108 cannon. This variant got the preliminary designation MK 213, as the 30 mm caliber meant that the weapon was classed as a cannon in German nomenclature. The 30 mm rounds on the MK 108 cannon had a fairly short cartridge with limited propellant capacity (30×90mm), and thus had a low muzzle velocity of around 550 m/s (1,800 ft/s). However, as they were adapted with mine shells, which could effectively knock out any aircraft at the time with just a few hits, they did not need high velocity to be effective against non-manoeuvering targets like bombers. Despite frantic efforts, production of the MK 213 never commenced due to development problems such as excessive barrel wear, not to mention the Allied Combined Bomber Offensive campaign against German industry. At the end of the war only 5 prototypes (V1 to V5) of either 20 mm MG 213 or 30 mm MK 213 were finished.
In the post-war era, the MK 213 became well known in armament circles, and a number of companies took up development. This included the Armament Development Establishment in the UK and GIAT in France. A common 30×111mm round) was developed that offered a dramatic improvement in muzzle velocity from the MK 108's 540 m/s to the new design's 790 m/s (2,600 ft/s). This was only slightly lower than contemporary 20 mm cannon like the Hispano Mk. V's 840 m/s (2,800 ft/s), making the new round suitable for use during dogfights as well as against larger targets. The mechanism improved the rate of fire from the Mk. V's 750 rpm to 1,300 rpm, a significant improvement. The new weapon was quickly developed and production was set up at the Royal Small Arms Factory in Enfield. The name ADEN was created by combining the two first initials of Armament Development Establishment with the first two letters of Enfield, producing ADEN.
The ADEN cannon entered service on the British Hawker Hunter in 1954, and was subsequently used on every British gun-armed aircraft until the advent of the Panavia Tornado in the 1980s. The last version to see production was the Mk. 4. An improved version, the Mk. 5, incorporates a multitude of small changes to improve reliability and increase rate of fire to 1,500-1,700 rounds per minute. No new Mk 5s were built, but many older weapons were converted, being redesignated "Mk 5 Straden".
The ADEN Mk 5 became the basis for the planned ADEN 25, which was to be a somewhat larger weapon at 90 in (2.3 m) long and weighing 203 pounds (92.1 kg) firing the new range of 25x137mm NATO STANAG 4173 ammunition (as developed for M242 Bushmaster) at a much higher muzzle velocity of 3,445 feet per second (1,050 m/s). The lighter ammunition was also to produce a higher rate of fire, 1,650 to 1,850 rounds per minute. The ADEN 25 was selected for British Harrier GR.5 aircraft. After initial weight issues and persistent problems integrating the cannon with the pod, and the pod with the Harrier GR.5 aircraft, the MoD considered the cost of fixing the problems excessive. and the project cancelled in 1999. As a result, RAF Harrier GR.7 and GR.9 aircraft did not carry a cannon, no attempt apparently having been made to retrofit the older ADEN 30 mm pods. Fleet Air Arm BAE Sea Harriers retained the 30 mm weapon until their retirement in 2006.
The ADEN gun has seen use in several gun pods including:
The Aden is belt feed using a disintegrating belt of open type links.
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