Aerojet has conducted a successful demonstration of its "scalable effects" warhead. The flight test was carried out on November 30, 2011, at the White Sands Missile Range in New Mexico using Lockheed Martin's new Guided Multiple Launch Rocket System-Plus (GMLRS+). As the name suggests, the scalable effects warhead allows the user to select the explosive yield of the weapon depending on the nature of its intended target.

The November 2011 flight test saw the GMLRS+ rocket score a direct hit on a target 30 miles (49 km) away. However, a GMLRS+ rocket featuring Aerojet's improved production motor was previously demonstrated in August 2011 over a range of 74 miles (119 km) - an improvement of some 31 miles (50 km) over the current GMLRS round.

"The 'scalable effects' warhead was set to low-yield prior to the flight and scored a direct hit on the target," said Scott Arnold, vice president of precision fires in Lockheed Martin's Missiles and Fire Control business. "The performance of both the GMLRS+ rocket and the scalable effects warhead were outstanding, validating our continued investment in evolving the proven GMLRS weapon system to address current and future threats."

The tests, supported by the U.S. Army's Precision Fires Program Office, were internally funded by Lockheed Martin and Aerojet.

A "scalable effects" warhead?

The ability to vary to explosive power of a warhead has clear implications for reducing risk to friendly forces, civilians and also reducing unnecessary damage to infrastructure other than the intended target. Historically, the notion of varying the explosive power of a warhead has been primarily linked with nuclear weapons, where the term "dial-a-yield" is generally used. In this case, the amount of material which can "boost" the yield (for example, tritium) can be varied, as can the performance of "initiators," which allow a chain reaction to propagate.

Achieving this with conventional (i.e. chemical) explosives presents different challenges. A plausible explanation of how this may be achieved would be varying the manner in which the explosive material contained in the warhead is detonated. However, Aerojet isn't giving away any secrets on how its scalable effects warhead is able to vary its yield.