ATLANTIC RESEARCH(ARC) has successfully ground tested a rocket-ramjet engine which could double the range of the Hughes AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM).

The June boost-sustain transition trial of the variable-flow ducted rocket (VFDR) was the final step before flight testing.

The VFDR is a solid-fuel rocket engine which transitions to ramjet operation, burning fuel-rich rocket-exhaust gases with air ducted into the combustion chamber.

Design features include a debris-free "nozzleless" booster, which eliminates the need for an ejectable rocket-boost nozzle. The solid-ramjet fuel generator allows for long-term storage of the missile, while a control valve modulates the gaseous fuel exhaust to provide variable thrust. This can be used to increase speed, decrease flight time and extend missile range.

The full propulsion-system demonstration was the culmination of a ten-year, $50 million, advanced-development programme conducted jointly by ARC and Alliant Techsystems.

The boost-sustain transition test involved a flight-type engine, which was configured to mate with the front end of the AMRAAM.

An ARC-developed system supplied air direct to the inlets, thus reducing the cost of simulating supersonic flight.

Source: Flight International