During the Cold War, the threat posed by tens of thousands of Soviet armored vehicles massed on the borders of Eastern Europe stimulated intensive development of antitank weaponry by NATO powers, including Great Britain. Particularly in the 1980s, NATO nations worked hard to develop anti-armor systems capable of killing hundreds of Warsaw Pact armored vehicles per hour – weapons like the AGM-114L Longbow Hellfire and BLU-108/CBU-97 Sensor Fuzed Weapon. The British entry into this family of weapons was to have been a missile called “Brimstone,” though a protracted development meant it arrived too late for Cold War service. The rebirth of Brimstone as “Dual Mode Brimstone” shows how creative engineering can adapt old weapon designs to new threats.

The rebirth of Brimstone as “Dual Mode Brimstone” shows how creative engineering can adapt old weapon designs to new threats.

Brimstone was originally conceived in 1996 as an evolution of the U.S. AGM-114 Hellfire, a laser-guided helicopter-launched antitank missile that began development in 1974. The RAF wanted a missile that could be carried by fast jets, and that could seek out enemy tanks autonomously, without requiring a pilot, or ground-based forward observer, to keep a laser tracker locked on the target until impact. In place of Hellfire’s semi-active laser seeker, Brimstone carried an active millimeter-wave radar seeker, operating at 94 GHz. It is relatively unaffected by rain, snow, fog, smoke, chaff, and battlefield dust. The seeker has a very narrow beam – only 1 degree wide – reducing the chance of detection by an enemy radar-warning receiver.

Brimstone was originally intended as a weapon for the Panavia Tornado, which made the missile’s designers give it a more robust airframe. With a navigator/weapon systems operator in the rear seat, Tornado allows the pilot to concentrate on flying the aircraft and avoiding threats. The RAF has also fitted Brimstone to the Eurofighter Typhoon, and had planned to integrate Brimstone on the Harrier jump jet until it was withdrawn from service in 2010. Like many modern digital weapons systems, the Brimstone program was subject to cost and schedule overruns, being cancelled in 1990 and re-started in 1992, finally entering service in 2005. Brimstone is carried and launched from a special triple rack compatible with NATO-standard aircraft pylons, so that a Tornado can carry up to 18, although a more typical mission load-out would be a mix of weapons, with 12 Brimstone on four racks. The Brimstone warhead is an advanced “tandem shaped-charge” designed to defeat the explosive reactive armor (ERA) fitted on modern tanks. A 300-gram (11 ounce) forward charge pre-detonates the ERA, dissipating its protective effect so that the main 6.2 kg (13.7 pound) charge can penetrate the target milliseconds later. This is also effective against bunkers, with the forward charge stripping away dirt or sand, allowing the main charge to explode with maximum demolition effects.

The missile was also one of the most effective munitions used against Gaddafi’s forces in Libya. Over 120 were fired, with a reported success rate of 98 percent.

The problem that made such a brilliant self-guiding weapon unusable was a new set of rules of engagement. On today’s battlefields, where civilians are mingled with irregular combatants, a school bus filled with children has pretty much the same microwave signature as a pickup truck filled with insurgents. The rules require a “man-in-the-loop” to visually monitor the engagement right up until the moment of impact. “Fire and forget” is no longer acceptable. The solution, driven by a British “urgent operational requirement” for the war in Afghanistan, was the addition of semi-active laser guidance. A miniaturized laser seeker was fitted behind a window in the blunt nose of the Brimstone, not interfering with the millimeter-wave radar. Retrofitted “Dual Mode” Brimstones entered service in 2008 with RAF Tornados flying over Iraq and Afghanistan. The results were impressive. The missile was also one of the most effective munitions used against Gaddafi’s forces in Libya. Over 120 were fired, with a reported success rate of 98 percent.

The following mission summary is typical:

“At dawn on Thursday morning, Tornados from Gioia del Colle [a NATO airbase in southern Italy] conducted an armed reconnaissance mission to Sebha, following reports that Gaddafi’s troops there were actively shelling the civilian population. “Previously during combat missions in both Libya and Afghanistan, the Brimstone missile has been fired individually, using laser guidance, with exceptionally accurate results.

“However, it also has the capacity to be fired in a large salvo utilizing millimetric radar to guide simultaneously each missile to a separate target. Since a large concentration of former regime armored vehicles had been located by NATO, this mission saw the salvo firing technique used for the very first time in action, with some two-dozen missiles fired.

“Full battle damage assessment continues, but seven or eight target vehicles were observed on fire, and the precision nature of the Brimstone’s warhead means that additional targets were most likely destroyed or severely damaged.”

Brimstone has now proven itself among the world’s great tactical missiles, and development is continuing. Its wartime successes have garnered attention from a number of potential foreign customers, and it is likely to be in service for many years to come.

 

Specifications

• Weight: 48.5 kilograms (108 pounds)

• Length: 1.8 meters (5 feet, 11 inches)

• Diameter: 17.8 centimeters (7 inches)

• Range: 12 kilometers (7.5 miles) being increased to 24 kilometers (15 miles)

• Speed: Supersonic