Army tests scramjet to power kinetic energy tank rounds.

• Author: Colucci, Frank
• Position: Munitions technology

The U.S. Army is testing a supersonic projectile that could drastically increase the killing power of future tanks.

The Armaments Research Development and Engineering Center, at Picatinny Arsenal, N.J., will test a supersonic combustion ramjet--scramjet--designed to improve the penetrating power of tank guns.

The scramjet, like common jet engines, burns fuel mixed with compressed atmospheric oxygen. However, unlike traditional jets, the scramjet has no compressor disks or other moving parts to compress the air. Hot air entering the scramjet inlets at four times the speed of sound, ignites the fuel and sustains combustion, so the scramjet itself contains pure fuel without wasting weight and volume of a separate oxidizer.

As it emerges ignited from a cannon barrel, a scramjet-powered tank round could produce thrust in flight to extend its range or sustain its penetrating power all the way to the target.

Compared to unpowered kinetic energy tank rounds that slow down and lose penetrating power to aerodynamic drag, a scramjet powered round could sustain its tank-penetrating power over longer ranges, or enable a smaller, lighter gun to achieve the same result.

Laboratory flight tests of a 101 mm demonstrator engine, scheduled from April to July of this year, may lead to a live-fire demonstration of a 120 mm round in a tank gun by 2005. Army researchers believe a scramjet-powered kinetic energy penetrating round will help give lighter fighting platforms an improved large caliber, direct fire capability.

With no moving parts, the scramjet engine burns fuel with the compressed, superheated air encountered at Mach 5--the muzzle velocity of existing tank guns.

Timing fuel combustion to the desired flight profile makes it possible to sustain the kinetic energy and penetrating power of tank rounds at extended ranges in direct-fire applications. Alternatively, the scramjet could extend the range of cannon rounds for indirect fires.

Unlike rockets, the scramjet wastes no fuel volume carrying oxidizer. "It's a way to provide more thrust per pound of round," explains Joe Snyder, aerospace engineer at the ARDEC Advanced Systems Concepts Office.

Accelerated to Mach 5 by the time it leaves the 120 mm gun of the Abrams tank, the standard M829A2 kinetic-energy round uses a finned "dart" to penetrate opposing tank armor and devastate the crew compartment without an explosive warhead. In Operation Desert Storm, one such penetrator reportedly pierced two Iraqi...