In the early 1980's the British Ministry of Defence initiated a project to develop and procure a new anti-armour weapon for the Royal Air Force's fixed wing aircraft. Till this time the BL-755 had served as the primary armour weapon. However it was becoming clear that against modern systems the weapon was beginning to show weaknesses. However the project faltered and was ultimately cancelled in 1990 following the Options for Change paper. Just two years later following a full assessment of Britain's and its allies role in the Gulf War the project was hastily re-instated under SR(A)-1238. In June 1995 five tenders were submitted fulfilling the requirement.
Hunting Engineering (manufacturers of the BL-755 cluster bomb for which SR(A)-1238 is intended to replace) proposed the SWAARM system. This comprised an un-powered guided (using millimetre wave radar and infra red) dispenser, once over the target area 36 SADARM shaped charges would be scattered. Texas Instruments proposed a very similar system to SWAARM in the form of the Grifin-38. Both weapons primary benefits were the stand-off introduced compared to the BL-755. The third proposal, Typhoon from Matra-BAe utilised a modified version of the ASRAAM air to air missile. Finally Thomson-Thorn proposed TAAWS a modified version of the BL-755, retaining the basic weapon but adding small rocket boosters to each charge increasing the stand-off range and coverage. However the winner of the project, announced in November 1996 was the Brimstone missile proposed by the UK's GEC (now Alenia-Marconi) teamed with Boeing of the United States. The total contract for development, production and support was placed at more than £1 Billion. Brimstone took the already highly successful Hellfire missile (as fitted to the Apache gunship) and made several improvements
Hellfire is available as two variants, one utilises laser designation while the second uses an RF based system. Brimstone however improves significantly upon both of these by incorporating a new MilliMetre Wave Radar (or MMWR) active seeker. The resolution offered by such a seeker provides Brimstone with ability to image targets. In addition the weapon can be pre-programmed with targetting and engagement information (assuming the aircraft has appropriate support) Combined these give Brimstone the ability to not only be specifically targeted but also to self-designate (and utilise appropriate engagement tactics) as required.
While Hellfire is launched from relatively slow moving platforms (helicopters), Brimstone must be capable of being launched and carried on fast moving platforms. To this end a new rail launch system has been developed by Flight Refuelling Ltd. (under contract to Alenia-Marconi) enabling safe carriage and release of the weapon by fixed wing aircraft. The launch assembly incorporates three individual rails thus allowing a significant number of weapons to be carried by a single aircraft (up to eighteen by a Eurofighter for example). Each weapon can be individually targeted and released by the launch aircraft. The system can be fitted with either a unitary or tandem warhead to counter reactive armour, detonation occurs upon impact.
Brimstone features a number of possible engagement profiles split between two modes, direct and indirect. If direct acquisition is possible the missile can be fired at that specific target. If several targets are to be attacked the missiles can be fired in salvo with each weapon taking either a common or dispersed path (depending on the positions of the targets). If a greater stand-off range is desired Brimstone can be launched at distance toward a target area. Both a minimum and maximum engagement range can be set to avoid friendly troops or collateral damage. Once over the area the missile can circle while its seeker tries to locate a target that matches one stored in its memory, the MMWR providing high resolution imagery. With a target aquired an appropriate impact point is selected and the missile dives toward it, exploding on impact. In both direct and indirect modes Brimstone utilises a common launch profile with the solid rocket boosting the missile to a supersonic velocity before burn out. After which the missile dives to a low altitude and coasts to the target using the MMWR as a terrain mapping radar.
In August 1999 Brimstone was sucessfully fired from a ground based launch system at the Yuma proving grounds in Arizona, USA. The first flight of Brimstone occurred on the 17th December 1998 aboard a DERA Tornado operating from BAe's Warton site. The aircraft was fitted with twelve weapons (four units of three missiles) which will comprise a typical load in combat scenarios. By the middle of 1999 several flights had taken place including the first release of a missile in August 1999. In December 1999 a second sucessfull surface launched test firing of the missile occured in Arizona aimed at examining the navigation and seeker electronics.
The production standard weapon is expected to be in-service on-board RAF Tornado's and Harrier's by 2002 with ground attack roled Typhoon's gaining the weapon when they enter service. In addition to air launched platforms Brimstone can also be deployed from surface facilities, vehicles and helicopters. One such possible future use is aboard the British Army's TRACER vehicle (a stealthy reconnaisance vehicle currently in development).
* : Note that all ranges quoted are based on mean figures from various data sources. Actual achievable range will depend on a great number of factors and may be no where near those quoted.