GRAHAM WARWICK / WASHINGTON DC
Raytheon and Aerojet to investigate possible applications under US Air Force contract
Raytheon and Aerojet are to study the potential of rocket/ramjet-powered air-launched missiles under a one-year US Air Force Research Laboratory contract. This follows on from the variable-flow ducted rocket (VFDR) ground tests conducted by Atlantic Research (ARC), now part of Aerojet, in the late 1990s.
The VFDR flight vehicle concepts study is aimed at developing a multi-mission missile that could enter service in 2010-15, says Pat Hewitt, director of air-breathing programmes at Aerojet. Air-breathing propulsion would provide the flexibility for the same missile platform to perform air-to-air and air-to-surface missions. The study will focus on packaging a VFDR-powered missile for carriage in internal weapons bays, he says.
The VFDR operates initially as a solid-rocket booster, then as a solid-fuel ramjet sustainer motor. The booster grain burns away quickly, creating a combustion chamber for the slower-burning, air-breathing ramjet. The hybrid propulsion system can provide two to three times the total impulse of a rocket motor, Hewitt says, increasing speed, range, or a combination of both.
In 1997, ARC completed ground tests of a flight-weight, 180mm (7in)-diameter VFDR to power a proposed extended-range version of the AIM-120 AMRAAM air-to-air missile. Now Aerojet is producing a 355mm-diameter VFDR to power Orbital Sciences' GQM-136A Coyote supersonic sea-skimming target, and a 255mm-diameter version for the US Navy's High-Speed Anti-Radiation Demonstration missile, with twice the range and two to three times the average velocity of the AGM-88 HARM anti-radar missile.
Source: Flight International
