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". GIAT also introduced their version of the design as the DEFA cannon; the two weapons are very similar. ADEN 25 The ADEN Mk 5 became the basis for the planned ADEN 25, which was to be a somewhat larger weapon at long and weighing firing the new range of 25x137mm NATO STANAG 4173 ammunition (as developed for M242 Bushmaster) at a much higher muzzle velocity of . 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. Aircraft use Built-in armament CAC Sabre English Electric Lightning Folland Gnat Gloster Javelin HAL Ajeet Hawker Hunter Saab Draken Saab Lansen SEPECAT Jaguar ST Aerospace A-4S Skyhawk Supermarine Scimitar Supermarine Swift As external armament The ADEN gun has seen use in several gun pods including: British Hawker Siddeley Harrier and BAe Sea Harrier, as well as the US Marine Corps AV-8A/Cs, carried two 30 mm ADEN gun pods below the fuselage of the