Army tests scramjet to power kinetic energy tank rounds.The U.S. Army is testing a supersonic projectile projectile something thrown forward. projectile syringe see blow dart. projectile vomiting forceful vomiting, usually without preceding retching, in which the vomitus is thrown well forward. 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 scramjet: see jet propulsion. , 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 ox·i·diz·er n. A substance that oxidizes another substance; an oxidizing agent. Also called oxidant. . 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 Adj. 1. unpowered - not having or using power; "an autogiro is supported in flight by unpowered rotating wings" powered - (often used in combination) having or using or propelled by means of power or power of a specified kind; "powered flight"; "kerosine-powered 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 su·per·heat tr.v. su·per·heat·ed, su·per·heat·ing, su·per·heats 1. To heat excessively; overheat. 2. 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 ARDEC Armament Research Development and Engineering Center (US Army) ARDEC Agence Rwandaise pour le Développement et la Coopération 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 finned adj. Having a fin, fins, or finlike parts. Often used in combination: single-finned; multifinned. "dart" to penetrate opposing tank armor and devastate dev·as·tate tr.v. dev·as·tat·ed, dev·as·tat·ing, dev·as·tates 1. To lay waste; destroy. 2. To overwhelm; confound; stun: was devastated by the rude remark. the crew compartment without an explosive warhead. In Operation Desert Storm Noun 1. Operation Desert Storm - the United States and its allies defeated Iraq in a ground war that lasted 100 hours (1991) Gulf War, Persian Gulf War - a war fought between Iraq and a coalition led by the United States that freed Kuwait from Iraqi invaders; , one such penetrator reportedly pierced two Iraqi T-72 tanks parked side-by-side. Despite their acknowledged effectiveness, kinetic-energy rounds lose about 100 miles-per-second velocity over 2 kilometers, due to drag. Since kinetic energy declines with the square of the velocity, armor penetration falls off at extended ranges. A scramjet propelled round could sustain the velocity and penetrating power of a tank gun round all the way to its target. Oversight for the Picatinny ARDEC is transitioning from the Tank and Automotive Armaments Command to the new Research, Development and Engineering Command, but the center remains the research focal point for gun armament systems. The ARDEC Advanced Systems Concepts Office broadened a scramjet program initiated by the Defense Advanced Research Projects Agency Defense Advanced Research Projects Agency (DARPA), U.S. government agency administered by the Department of Defense (see Defense, United States Department of). and the Office of Naval Research The U.S. Office of Naval Research (ONR), headquartered in Arlington, Virginia (Ballston), is the office within the U.S. Department of the Navy that coordinates, executes, and promotes the science and technology programs of the U.S. . Tyrus Cobb, chief of the ASCO ASCO American Society of Clinical Oncology ASCO Association of Schools and Colleges of Optometry (since 1941; Rockville, Maryland) ASCO Australian Standard Classification of Occupations ASCO Automatic Switch Company requirements analysis division explains, "That's what we're all about, looking at futuristic stuff that will enhance our armament applications." Scramjet technology has potential applications in anti-ship missiles and other platforms. Allied Aerospace received a contract under the DARPA/Navy Small Business Innovative Research program to demonstrate scramjets in the supersonic wind tunnel A supersonic wind tunnel is a wind tunnel that produces supersonic speeds (1.2 "We were looking to find a means to test scramjets in flight for lower cost," explains vice president of engineering Robert Bakos. He notes a gun-launched scramjet could be tested in the 1,000-foot tunnel at the AEDC AEDC Arnold Engineering Development Center (Tullahoma) AEDC American Economic Development Council AEDC Anchorage Economic Development Corporation AEDC Antarctic Environmental Data Centre (UK) for a fraction of the cost of a rocket-boosted vehicle. Four test firings from a 101 mm light gas gun in July 2001 proved a scramjet engine could sustain Mach 7 in thin air at a simulated 100,000-foot altitude. Informal networking by engineers at the Picatinny ASCO and DARPA DARPA: see Defense Advanced Research Projects Agency. (Defense Advanced Research Projects Agency) The name given to the U.S. Advanced Research Projects Agency during the 1980s. It was later renamed back to ARPA. resulted in a Cooperative Research and Development Agreement “CRADA” redirects here. For other uses, see CRADA (disambiguation). A Cooperative Research and Development Agreement (CRADA) is an agreement between a government agency and a private company to work together. with Allied Aerospace to produce a "gun-hardened" engine for Mach 5 launch at sea level. The company first demonstrated scramjet technology in 1961 and has worked on the National Aerospace Plaine, the Hyper-X, and other hypersonic hy·per·son·ic adj. Of, relating to, or capable of speed equal to or exceeding five times the speed of sound. hy research applications. Subsonic sub·son·ic adj. 1. Of less than audible frequency. 2. Having a speed less than that of sound in a designated medium. subsonic Adjective ramjets transition to supersonic scramjets around Mach 5--five times the speed of sound. Fuel metered into the hypersonic airstream ignites spontaneously. According to Bakos, "What you're trying to do is control the supersonic flow through the engine, and add heat to it, and make it produce thrust. It's a delicate balance of many opposing large forces." The demonstrator engine burned gaseous ethylene in eight combustion chambers. Engineers optimized the scramjet inlet ducts and fuel injectors for a Mach 7 flight with 10,000 G acceleration. The Army's follow-on effort refines the design to withstand the 60,000 G load of a main tank gun and the sustained heat of hypersonic flight. "You're flying very fast with a lot of heat transferred to the vehicle," observes Bakos. "The vehicle has to sustain those loads without weakening." In DARPA tests, the 101 mm (4-inch) diameter titanium demonstrator engine flew 260 feet before it vaporized va·por·ize tr. & intr.v. va·por·ized, va·por·iz·ing, va·por·iz·es To convert or be converted into vapor. va on impact with the steel plates at the end of the test tunnel. Though the missile shape was aerodynamically unstable, the engine produced thrust throughout its 30-meter flight. "There wasn't enough time for the projectile to turn over," says Snyder. The ARDEC-sponsored demonstration will combine a refined motor with a penetrator, stabilizing fins and discarding sabot designed by Army engineers at Picatinny. Building a scramjet round able to withstand acceleration forces six times those encountered in the original demonstration presents design and material challenges. Simply thickening the walls between the combustion chambers would reduce fuel volume and air flow. High strength materials are essential to produce a gun-hardened scramjet round. Target throw weight of the engine plus penetrator is 23 pounds. "We're looking to lighten-up anywhere we can," says Snyder. The ARDEC demonstration in the Arnold tunnel calls for two unpowered aerodynamic shapes of a representative mass to validate the important stabilizing fins. Three scramjet-powered rounds will then test the integration of the engine, penetrator and fins. A four-piece composite sabot like that used on standard tank rounds seals the gun tube to capture the pressure from burning launch propellants and increase muzzle velocity, then breaks away in flight. The powered rounds are expected to travel the full 1,000-foot length of the test tunnel at Mach 5 at sea level (1,700 miles per second). Successful demonstrations may lead to a tactical 120 mm round development program for the Future Combat System's tank-like mounted combat system. Similar rounds could be incorporated in the Stryker brigade mobile gun system and Abrams tank, officials said. Advanced Systems Concepts Office director Eugene Del Coco, explains, "You can continue to improve the performance of existing weapons systems by adding new munitions mu·ni·tion n. War materiel, especially weapons and ammunition. Often used in the plural. tr.v. mu·ni·tioned, mu·ni·tion·ing, mu·ni·tions To supply with munitions. and new technology." The test engine continues to use gaseous ethylene fuel for its short tunnel flight. A useable scramjet-powered kinetic-energy round would require solid propellant to reach 4 km or more, and to provide a safe, easily-handled round with a shelf life of 20 years or longer. The ARDEC Energetic Materials branch will evaluate alternative fuels for tactical trials, and Allied Aerospace is working with Alliant Tech Systems to identify suitable solid propellants. The ideal line-of-sight, direct-fire kinetic energy round might discard its motor after fuel burn out to eliminate parasitic drag on the penetrator. While the current goal is a 120 mm round to fit future and existing guns, the technology could potentially boost the velocity and increase the lethality of smaller rounds to support development of smaller guns carried by lighter, more agile vehicles. |
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