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Barrage Round (BarRnd)

The high speed, gun launched, barrage round projectile demonstration program included gun launch of high velocity, unguided flight test vehicle to range (>40nmi) and preliminary lethal mechanism tests supporting Marine Corps Volume of Fire Requirements. This program was completed in FY2002. The Barrage Round project successfully completed projectile demonstrations which proved the viability of an accurate, guided very low cost soft target volume round for 5" guns.

On 11 January 2002, an advanced projectile, the 40 pound Barrage Round, was fired to a range of 40 nautical miles (about 46 statute miles or 74 kilometers). By way of comparison, existing 5" high explosive rounds achieve ranges of just 13 nautical miles. The Barrage Round was fired from a standard Navy 5"/54 caliber gun and reached the maximum range in less than three minutes.

Naval gunfire is one of the most important sources of fire support for Marines conducting amphibious operations. The 5" gun is the standard fire support weapon carried by United States Navy cruisers and destroyers. A cruiser can carry as many as 1200 Barrage Rounds in its magazines. Fully compatible with existing auto-matic loading systems, they can be fired less than 90 seconds after a ship receives a call for fire.

The Office of Naval Research sponsored development of the Barrage Round by the Naval Surface Warfare Center Dahlgren Division. The new projectiles improve on existing 5" high-explosive ammunition in that they offer much longer range, higher speed, and a greater ability to damage or destroy targets. Greater accuracy is achieved with a miniaturized guidance package that combines the Global Positioning System (GPS) with low-cost, commercial-off-the-shelf inertial sensors. This advanced system gets its small size and ability to with-stand the stresses of firing from recent advances in micro-electro-mechanical sensors.

The Barrage Round does not use a rocket, but instead achieves its higher velocities through a system of "sabots" - devices that hold a smaller caliber shell inside a larger gun tube and fall away from the shell as it leaves the muzzle of the gun. Sabots have long been used to achieve very high velocities in tank guns, but Barrage Round is the first to use the technology in firings from large-caliber Navy weapons. When it explodes at its target the Barrage Round dispenses a large number of flechettes-small, metal arrows. The Barrage Round was developed under Office of Naval Research sponsorship in a government-industry partnership, this one led by the Naval Surface Warfare Center Dahlgren Division, SAIC, and CAES.

A major attribute of electromagnetic guns of either the rail or coil variety is their potential for launching projectiles at high muzzle velocities, well beyond those of conventional guns. The potential operational benefits include longer ranges, shorter flight times, and increased impact speeds. Prior to 2002 most of the work done by the Center for Naval Analysis [CNA] on this technology dealt with railguns, for which CNA formulated a design that was adopted by the research and development community as a notional baseline for the Navy in its pursuit of electromagnetic launch technology. The projectile used in this analysis was based on the Navy Barrage Round.

An important next step was to establish the viability of the projectile technology at hypersonic speeds and validate the lethality estimates against a spectrum of targets. Both avenues could likely be pursued at funding levels below those required to build, demonstrate, and test a full-scale gun. The Barrage Round program provided a good path for projectile technology development. CNA's recommendations were to: pursue a full-scale railgun demonstration as soon as possible, as an electromagnetic launch proof-of-concept. Then, if successful, pursue both rail and coil technologies to mitigate risk prior to an ultimate decision on an operational system. If funding is available, develop both technologies simultaneously with a goal of full-scale demonstration.

The specific mission of Time Critical Strike (TCS) integrates surveillance, indications and warnings, target identification, targeting, fire order generation and dissemination, engagement and kill mechanisms, and damage assessment processes to address critical mobile targets, urban targets, short dwell targets and deeply buried targets. Time Critical Strike must address time sensitive targets in complex urban areas over crowded skies shared with civilian commercial and neutral country aircraft. High quality, timely sensor information, target identification, and course of action analysis is required to enable distributed collaborative planning and the generation of retargeting folders for strike platforms. Unmanned combat air vehicles will be investigated to effectively and affordably prosecute strike and surveillance missions. The approach must be responsive in that it can reduce the strike timeline against time critical targets. The support required to accomplish this also requires high-speed sealift. The technologies reduce the time to conduct strike in all functional areas of the kill chain: detect decide, engage, and battle damage assessment. Intelligence processing, execution speed, command decisions, and accuracy of strike are in constant tension.

Time Critical Strike conducted risk reduction in the areas of Surface Fire Support and real time retargeting for gun launched ordnance for the purpose of delivering ordnance to land targets. Various efforts in Naval Fire Support in 0602111N were focused on preliminary risk reduction in preparation for the advanced development TCS efforts. The Barrage Round project successfully completed projectile demonstrations, which proved the viability of an accurate, guided projectile in modern strike warfare. (FY-01 accomplishments were funded in PE 0602111N and PE 0603217N).

The Barrage Round was a technology demonstration of a high speed kinetic energy projectile with a flechette payload. Development of this projectile will encourage new high-pressure guns with large chambers to increase the range and lethality of such a projectile. Because the Barrage Round is a sub-caliber projectile with a fine conical shape, it requires a sabot and pusher plate for launch. Ordinarily, a high performance sabot and pusher plate for use in a high pressure, high energy gun would require high cost, exotic materials, difficult designs, and elaborate fabrication processes. This need not be the case, however. Current sabot/ pusher designs for the conical shaped projectile being considered here, launched at a 37 kgee peak acceleration, are expected to add 15% to the launch mass. Advanced designs, materials, and fabrication methods can be expected to reduce that value to only a few percent, but new issues arise: what does the optimum design look like, what materials should be used, do suitable manufacturing methods exist, and what are the production costs.

Barrage Round was demonstrated with a sabot and pusher-plate design fabricated of high strength aluminum, fabricated by traditional methods. All the truly high payoff concepts can be expected to require a considerable investment in new material and manufacturing technologies. This would provide a low cost, high performance sabot and pusher plate for the Barrage Round projectile that minimizes parasitic mass through innovative new design approaches, high specific strength materials, and novel fabrication techniques.

A 2001 SBIR topic sought the solution with the highest performance payoff but at a cost that is commensurate both with its lethality benefit to the round and the cost of the round itself. It is expected that through a host of unexplored design solutions such as geometry changes in petal sections, bore rider material choices and accompanying obturator designs, contact surface coatings, and separation strategies that support both low- cost and high performance procurement decisions that still provide 50% or greater reductions in sabot/ pusher plate mass.

Phase I: Conduct a first-principals structural dynamics analysis of proposed new sabot and pusher designs and compare the mass and cost-to-manufacture of those results with traditional aluminum designs for the baseline launch conditions of 80 ksi peak pressure, 37 kgee peak acceleration, and 16 kg flight mass. Include at least one composite-based design alternative. The contractor may find it desirable to interface with the Navy Mantech Center for Composites Manufacturing in FY 01 and develop a quick response effort to obtain their assistance.

Phase II: Iterate Phase I composite designs to improve manufacturability. Develop mass vs. cost trade off estimates for performance comparisons with traditional designs. Using manufacturable designs, produce composite sabot/ pusher plates for Phase III flight tests.

Phase III: Integrate and test the Phase II prototype improved sabot and pusher plate in an operational Mk 45 Gun system. Test firings shall be conducted with slugs weighing 16 kg, fired at muzzle energies of 18 and 25 MJ with NSWC Indian Head propelling charge designs. A test series of at least 50 rounds shall be performed to allow evaluation of improved sabot/ pusher design.

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