US Air Force eyes flight of ramjet missile

After decades of research, US Air Force engineers say they are now on the cusp of testing in flight a novel solid-fuelled propulsion system designed for next generation air-to-air missiles.

However, standing in the way of them flight testing this Variable Flow Ducted Rocket (VFDR) system - a type of ramjet - is a lack of funding, since the missile work has to compete with more pressing service priorities. Nonetheless, engineers said they are hopeful that the funding will materialise in the next few years.

Developmental efforts by the Air Force Research Laboratory (AFRL) to date have matured the preliminary flight design of a
VFDR-powered missile concept.

While Europe's MBDA is developing the ramjet-powered Meteor beyond-visual-range air-to-air missile, the VFDR concept is the only US air-to-air system of this ilk.

The VFDR-powered missile would offer a "significant increase" in range over current beyond visual-range missiles and displays higher average velocities than contemporary short- and medium range missiles, said Mike Valentino, programme director for VFDR Flight Vehicle Concepts in the air vehicles branch of the AFRL's Munitions Directorate at Eglin Air Force Base (AFB), Florida.

Such a missile design could potentially enter the air force's inventory in the middle to late part of the next decade to complement and eventually replace the AIM-9X Sidewinder short-range missile or the AIM- 120 Advanced MediumRange Air-to-Air Missile (AMRAAM).

The AFRL's 7 in-diameter VFDR model is in the same size class as the AMRAAM, and its inlets have been sized for compact carriage in the internal weapons bays of the F/A-22 Raptor and F-35 Joint Strike Fighter, in addition to other AMRAAM carriage concepts, said Fred Davis, technical director of the directorate's assessment and demonstrations division. The AFRL is "very encouraged" by the design, Davis told .JDW.

The air force has expressed interest in its next air-to-air missile potentially serving in a dual role, so engineers have also examined three concepts that could apply to the VFDR design: a short-and medium-range air-to-air system; a medium-range air-to-air missile with the ability to attack ground targets; and a missile that could perform all three functions.

Raytheon led the industry team that included engine-manufacturer Aerojet in work on the design. The air force's VFDR work began in 1986, said Bob Mercier, deputy for technology in the AFRL's aerospace propulsion division at Wright-Patterson AFB.

Progress has been intermittent due to funding instability. In 1997, the AFRL conducted a ground test of a flight-weight engine. Valentino said a flight test programme would probably last about three years and include several flights to validate performance.

The VFDR concept uses a solidfuel rocket motor booster that rapidly accelerates the missile to supersonic speed.

After the booster propellant burns off, a gas generator then creates a fuel-rich gas that acts as the fuel for the ramjet for the remainder of the missiles flight.

Source: www.janes.com

Is this PDE tech same as the ramjet tech or something different?

So sferrin, have you got any detail on this ramjet principle other than briefly mentioned above or shortly, what is the difference?

What are the chances we see these in use on our aircraft 4-5 years down the road?