DARPA hypersonic scramjet projectile flies

The Defense Advanced Research Projects Agency (DARPA) announced today the
first-ever successful free flight of a hypersonic projectile powered by a
supersonic combustion ramjet (scramjet) engine burning hydrocarbon fuel. The
projectile is a four-inch diameter, 20-percent scale model of a conceptual
missile. On July 26, GASL Inc., of Ronkonkoma, N.Y., fired the scramjet
projectile out of a large gun at the Air Force’s Arnold Engineering
Development Center, Arnold AFB, Tenn. The test is an important step towards
the realization of flight at hypersonic speeds.

The test was the second of two successful launches, the first occurring on
June 20. Together, these tests demonstrate that scramjet engines will provide
enough thrust to power a free-flying vehicle.

The tests used Arnold Engineering Development Center’s two-stage light gas gun
to accelerate the projectile to the flight condition through a 130-foot long
gun barrel. The projectile experienced peak acceleration of approximately
10,000 Gs, and was launched from the gun at Mach 7.1. Arnold’s G-Range
facility is the only range in the country capable of providing the low-
acceleration loads required to launch the projectile. After the titanium
projectile was launched, it used its scramjet engine to cover a distance of
260 feet in slightly over 30 milliseconds.

Scramjet engines provide propulsion at speeds above Mach 5 by capturing
atmospheric air to burn on-board fuel. These air-breathing engines are more
efficient than rocket motors for hypersonic propulsion, and will ultimately
allow the possibility of longer duration flight with greater payload.
Applications for such engines include powering long-range hypersonic missiles,
gun-launched kinetic energy weapons, and access to space vehicles. In order
to operate, scramjet engines must first be traveling at hypersonic speed.
An accepted approach to reach scramjet take-over speeds is to attach the
scramjet to a rocket booster as a first stage and then operate the scramjet
once the rocket has increased the speed sufficiently.

Additional launches are planned, with higher performance scramjet engines and
longer flight durations. GASL is performing the tests under a Phase II Small
Business Innovation Research contract with DARPA.

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Media with questions, please contact Jan Walker, (703) 696-2404, or
jwalker@darpa.mil . (Contractors or military organizations should contact
Dr. Preston Carter, (703) 696-7500, phcarter@darpa.mil .)