Tweet
US ARMY SCRAMFIRE 120mm tank round
Army Tests Scramjet to Power Kinetic Energy Tank Rounds
by Frank Colucci
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 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 and the Office of Naval Research.
Tyrus Cobb, chief of the ASCO 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 at the Arnold Engineering and Development Center at Tullahoma, Tenn.
“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 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 resulted in a Cooperative Research and Development Agreement 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 Plane, the Hyper-X, and other hypersonic research applications. Subsonic 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 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 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
http://www.nationaldefensemagazine.o...le.cfm?Id=1170
Mac's in the Army Now
For her part, Kerr believes the selection of Xserves by COLSA Corporation [Blane Warrene, "US Army Drafts Apple Xserve for Supercomputer" MacNewsWorld, June 22, 2004] for advanced U.S. Army research, confirms Apple's commitment to becoming a larger player in the high-performance computing market.
In an interview with MacNewsWorld, George Landingham, deputy director of systems simulation development with the U.S. Army's Aviation and Missile Research Center at Redstone Arsenal in Huntsville, Alabama, said his group hopes that the Xserve-based MACH5 will reduce dramatically the time it takes to analyze data on hypersonic flight. This analysis includes what he called "computationally intense equations regarding combustion and chemistry."
Landingham said his group's research is focused on scramjet technology, which can propel vehicles at speeds of Mach 8 to Mach 12 -- the equivalent of 4,800 to 7,200 miles per hour.
"We were held back in previous attempts to solve these equations due to system limitations for processing data," Landingham said. "We need to analyze fuel being injected, air flow and fuel being combusted at hypersonic speeds, not a simple task."
Dr. Anthony DiRienzo, executive vice president at COLSA Corporation, told MacNewsWorld that the scramjet data the U.S. Army needs analyzed is three-dimensional, and in the past, processing just a few milliseconds of it would take months. With the MACH5, Army researchers will be able to process upwards of 16 equations on 8 million cells of data overnight.
According to Landingham, once the system goes into production in November at COLSA, Army scientists will begin processing data. If successful, they might seek to expand projects on the MACH5.
"This research is part of the National Aerospace Initiative," he said. "We'll have to wait and see how it goes, but certainly we have other problems to solve which we could use this system for."
The NAI is a joint effort between the US Army's research arm, NASA Latest News about NASA and the Defense Advanced Research Projects Agency.
http://www.macnewsworld.com/story/34812.html
Here's some basic US Scramjet program info from wikapedia:
HyShot
On July 30, 2002, the University of Queensland's HyShot team successfully conducted the first ever test flight of a scramjet.
The team took a unique approach to the problem of accelerating the engine to the necessary speed by using an Orion-Terrier rocket to take the aircraft up on a parabolic trajectory to an altitude of 314 km. As the craft re-entered the atmosphere, it dropped to a speed of Mach 7.6. The scramjet engine then started, and it flew at about Mach 7.6 for 6 seconds. [1]. This was achieved on a lean budget of just A$1.5 million (US $1.1 million), a tiny fraction of NASA's $US 250 million to develop the X-43A.
NASA has partially explained the tremendous difference in cost between the two projects by pointing out that the American vehicle has an engine fully incorporated into an airframe with a full complement of flight control surfaces available.
No net thrust was achieved. (The thrust was less than the drag.)
[edit]
Hyper-X
NASA's Hyper-X program is the successor to the National Aerospace Plane (NASP) program which was cancelled in November 1994. This program involves flight testing through the construction of the X-43 vehicles. NASA first successfully flew its X-43A scramjet test vehicle on March 27, 2004 (an earlier test, on June 2, 2001 went out of control and had to be destroyed). Unlike the University of Queensland's vehicle, it took a horizontal trajectory. After it separated from its mother craft and booster, it briefly achieved a speed of 5,000 miles per hour (8,000 km/h), the equivalent of Mach 7, easily breaking the previous speed record for level flight of an air-breathing vehicle. Its engines ran for eleven seconds, and in that time it covered a distance of 15 miles (24 km). The Guinness Book of Records certified the X-43A's flight as the current Aircraft Speed Record holder on 30 August 2004. The third X-43 flight set a new speed record of 6,600 mph (10,621 km/h), nearly Mach 10 on 16 November 2004. It was boosted by a modified Pegasus rocket which was launched from a Boeing B-52 at 13,157 meters (40,000 feet). After a free flight where the scramjet operated for about ten seconds the craft made a planned crash into the Pacific ocean off the coast of southern California. The X-43A craft were designed to crash into the ocean without recovery. Duct geometry and performance of the X-43 are classified.
[edit]
Russia and France (and NASA)
On November 17, 1992, Russian scientists with some additional French support successfully launched a scramjet engine in Kazakhstan. From 1994 to 1998 NASA worked with the Russian central institute of aviation motors (CIAM) to test a dual-mode scramjet engine. Four tests took place, reaching Mach numbers of 5.5, 5.35, 5.8, and 6.5. The final test took place aboard a modified SA-5 surface to air missile launched from the Sary Shagan test range in the Republic of Kazakhstan on 12 February 1998. Data regarding whether the internal combustion took place in supersonic air streams was inconclusive, according to NASA. No net thrust was achieved. The tests also included French partners.
[edit]
GASL projectile
At a test facility at Arnold Air Force Base in the U.S. state of Tennessee, GASL fired a projectile equipped with a hydrocarbon-powered scramjet engine from a large gun. On July 26, 2001, the four inch (100 mm) wide projectile covered a distance of 260 feet (79 m) in 30 milliseconds (roughly 5,900 mph or 9,500 km/h). The projectile is supposedly a model for a missile design. Many do not consider this to be a scramjet "flight," as the test took place near ground level. However, the test environment was described as being very realistic.
http://en.wikipedia.org/wiki/Scramjet
SCRAMFIRE:
U.S. ARMY/ USN
Scramfire
Scramfire is a 120-mm powered munition “that accelerates throughout flight to the target and offers increased velocity at the target for direct fire weapons or increased range for indirect fire” (CAS, 2003). The scramjet-powered munition (see Figure C-2) demonstrated structural integrity by inflight x-ray and had a self-sustaining thrust that enabled a flight velocity of 8,100 ft/sec over 240 ft flight (Sega, 2003).
Hypersonic Interceptor Missile Scramjet Program
Provide optimized design for a Mach 10-12 H2 fueled scramjet powered interceptor missile to be used for defense against cruise missiles and for Army long range attack operations.
http://www.nap.edu/openbook/0309091756/html/113.html
Comment