GUY NORRIS / LOS ANGELES

A TRW-built rocket engine powered by gelled propellant has successfully completed a series of cold test firings, clearing the way for possible applications over a range of US Army tactical missiles including the Common Missile, Modernised Hellfire, THAAD, Advanced Kill Vehicles and the Low Cost Interceptor.

Gel propulsion systems are usually fuelled with a semi-solid propellant, in the case of tactical missiles, consisting of metallised gelled propellants. Metal additives, such as aluminium, are suspended in a gelled hydrogen or hydrocarbon fuel and undergo combustion with an oxidiser. The result, says TRW, is a fuel that combines the best characteristics of solid and liquid propellants as the gel system can be stored like a solid rocket propellant, but flows like a liquid when pressurised. This enables the rocket to be throttled and restarted, just like a liquid-fuelled version.

Gel systems are considered safer than liquid because they do not leak, spill or explode. They also offer higher specific impulses and can be used to control the energy to achieve long range. Also, because they are capable of completely shutting off and restarting several times, gelled systems can allow missiles to coast, which conventional solid motors cannot provide.

Testing forms part of the Controllable Thrust Propulsion (CTP) programme and is a follow-on to the US Army's Future Missile Technology Integration programme. One of the first potential applications could be the Common Missile, which is a multi-purpose weapon designed for ground and air launch against a range of targets. If it goes ahead, first deliveries could be expected in 2008-10, with a production run of up to 16 years and 73,000 missiles divided between the USA and the UK - partner in the concept and technology demonstration phase.

TRW, one of several companies working on CTP, says it "will hopefully be part of one or more prime contractor team when the bidding starts for the Common Missile procurement". A request for proposals is due next January with awards expected in October 2003. Work on the CTP is meanwhile expected to continue. Under this effort TRW is completing system design and starting work on the detailed design of the gas generator.

Source: Flight International