covering and then release its 12.7 inch Mark 44 or Mark 46 acoustically-guided anti-submarine torpedo. The torpedo payload would descend by parachute while the missile itself was programmed to splashdown some distance away to avoid interference with the acoustic torpedo's seeker head. The torpedo would then begin a circular search pattern to find and lock onto a submarine contact. In 1982, work began on an improved version, the Super Ikara. This was to be turbojet-powered to give a maximum range of , and would be carried in, and launched from a container. While test launches were carried out in 1986, the project was abandoned due to a lack of interest from the UK. British variant differences A variant fitted to the British Royal Navy's s differed in several respects from the original Australian version designed to operate in the Pacific. The Royal Navy required changes to the frequencies used in order to enable Ikara to be used in the NATO area, where different electronic warfare conditions and international frequency agreements had to be taken into account. Neither the Australian-built analogue computer system, nor the American Bunker Ramo Corporation 133 digital computer system, used in most RAN systems, were compatible with the ADA digital battle-control computers being fitted into Royal Navy ships, and this was also changed. The UK-manufactured version of the Mark 44 torpedo also differed from the US-built version purchased by the Australians for their Ikara missiles. The British also required the missile payload to be changeable aboard ship to permit different payload combinations to be used, including a nuclear depth bomb (NDB) option, and this, together with the different internal ship layouts required further changes to the missile, storage and handling arrangements. The Australian practice was to combine the missile and payload at a shore-based ordnance facility and issuing the complete unit to a ship; repair or maintenance was only possible ashore. In the British ships, the changes made enabled a faulty torpedo on a missile in working order to be replaced, increasing the flexibility of use of very limited stocks aboard; especially on lengthy deployments around the globe, as was more common with British ships than their Australian counterparts. The facility to change a torpedo payload aboard ship also permitted a change from a conventional torpedo to a WE.177A NDB, a facility for a nuclear option that was not needed on ships fitted with the Australian variant