Ballistic Trajectory Extended Range Munition (BTERM)
Autonomous Naval Support Round (ANSR)

The Ballistic Trajectory Extended Range Munition (BTERM) was designed to employ a high-speed ballistic trajectory with a GPS/INS guidance solution to provide the U.S. Navy with a long-range 5-inch precision projectile to meet Naval Surface Fire Support (NSFS) requirements. The BTERM used the Low-Cost Guidance Electronics Unit (LCGEU), a Global Positioning System/Inertial Navigation System (GPS/INS) guidance system developed for the Navy and modified for BTERM by the C.S. Draper Laboratory, Cambridge, Massachusetts.

BTERM was designed to be compatible with the Navy's existing inventory of 5-inch/54-caliber gun mounts as well as the newer 62-caliber guns. The projectile would provide the Navy with an alternative solution to meet the demanding requirements of a next-generation surface fire support capability.

ATK Missile Systems Company, Woodland Hills, California, together with its Guided Projectile division at the Allegany Ballistics Laboratory (ABL) in Rocket Center, West Virginia, was responsible for BTERM system integration and the projectile's solid propellant rocket motor. Other members of the BTERM team were the C.S. Draper Laboratory, Cambridge, Massachusetts (prime contractor, guidance electronics and navigation), and Custom Analytical Engineering Systems (CAES), Cumberland, Maryland (airframe and control actuation). The BTERM demonstration program benefited from the U.S. Navy's extensive facility restoration program at ABL that was strongly supported by Senator Robert C. Byrd (D-W. Va.).

BTERM is an extension of the Autonomous Naval Support Round (ANSR), a boosted projectile that flew a world record 54 nautical miles in a ballistic flight test conducted in 2003. The Autonomous Naval Support Round (ANSR) warhead as designed was a derivative of that in the HARM anti-radar missile, weighs approximately 25 pounds, including ten pounds of explosive, and is fitted in a tungsten case that will fragment on detonation. The fragmenting warhead, coupled to a precision-guidance system, provided an estimated four times the lethality of a steel-cased warhead of equivalent size. When the shell reaches its target, ANSR showers the area with pre-formed metallic fragments embedded in a composite matrix.

Naval gunfire has been one of the most important sources of fire support for Marines conducting amphibious operations. The 5" gun has been the standard fire support weapon carried by United States Navy cruisers and destroyers. A cruiser could potentially carry as many as 600 ANSR rounds in its magazines. Fully compatible with existing automatic loading systems, they could be fired less than 90 seconds after a ship receives a call for fire.

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

The ANSR round as designed was a rocket-assisted projectile, that is to say a rocket motor in the base of the shell increases the projectile's speed (and therefore its range) by augmenting the propulsive force of the conventional gun propellant. ANSR was developed under Office of Naval Research sponsorship in a government-small business partnership between the Naval Surface Warfare Center, Dahlgren Division and CAES. In FY02, prime contractor Alliant Techsystems (ATK) invested corporate resources to demonstrate the range, lethality and guidance accuracy of the ANSR system.

On 9 January 2002, the ANSR was successfully fired out to a range of slightly more than 51 nautical miles (about 59 statute miles or 95 kilometers). By way of comparison, 5" high explosive rounds then in existence could achieve ranges of just 13 nautical miles. ANSR was fired from a standard Navy 5"/54 caliber gun and reached the maximum range in less than three minutes. A 10 July 2003 flight test was the first successful employment of a Selective Availability Anti-Spoofing Module (SAASM)-capable GPS receiver to acquire military navigation signal in a gun-launched projectile.

On 24 September 2003, at the White Sands Missile Range (WMSR) in New Mexico, ANSR flew more than 61 miles (54 nautical miles) in less than three minutes. Using inputs from up to nine GPS satellites, the projectiles were guided to within 20 meters of their designated targets. The objectives for each test were fully satisfied as were all the system performance objectives established for the 17-month Ballistic Trajectory Extended Range Munition (BTERM) technology demonstration program.

In May 2004 the BTERM II, an extension of the earlier ANSR, captured the highly competitive award for development of the Navy five-inch Extended Range Munition (ERM). With a value of $30 million, the contract called for ATK to perform a 16-month demonstration of an innovative extended range, low cost, gun launched projectile capable of operation in the Mk 45 Mod 4 and Mod 2 naval gun systems. The contract was a result of challenges in developing ERM.

Two additional BTERM test firings demonstrated remaining program objectives. A US Navy-industry team that included ATK achieved a milestone in the demonstration of a transformational stand-off combat capability: Navy gun-fired, long-range, precision-guided projectiles in support of ground maneuver warfare. During a test conducted 10 July 2004 at the White Sands Missile Range in New Mexico, the BTERM completed its first boosted guided flight test. The projectile was fired from a 5-inch/62-caliber gun using standard NACO propellant and flew over 32 nautical miles down range. Preliminary results indicated most primary test objectives were met: airframe and electronics survived gun launch, the rocket motor ignited as expected and the BTERM guidance system successfully acquired precision navigation signals from eight GPS satellites, formulated an on-board navigation solution, and issued appropriate guidance commands.

ATK conducted an engineering test of a redesigned rocket motor with an unguided round at White Sands on 31 October 2005. The redesigned rocket suffered an early motor burnout, leading to a cancellation of a test planned for 4 November 2005. On 21 February 2006 the BTERM development team, Alliant Techsystems, the United States Navy, The C.S. Draper Laboratory, and CAES, successfully conducted a challenging short-range, unboosted, guided flight test of ATK's BTERM in support of the Navy's ERM requirement. In this engineering test, the advanced BTERM guided projectile flew more than 8 miles and landed within two meters of the target. It was the latest in a series of engineering tests leading up to planned guided and boosted flight-tests scheduled for Spring 2006.

The flight test achieved all test objectives including high-g gun launch survivability, muzzle exit conditions, guidance accuracy and terminal angle. The test demonstrated the guidance section's ability to meet accuracy requirements under difficult short time of flight conditions. The guidance section contained the Low Cost Guidance Electronics Unit (LCGEU) and an innovative single axis control actuation system. Combined, these units provided a robust and affordable solution for accurately guiding gun-launched munitions within a few meters of a target.

The BTERM munition's rocket motor caused test failures that led the Navy to abandon plans to recompete the development contract for ERM. In a March 2007 Government Accountability Office report a US Navy official stated that the US Navy concluded that ERM was a more viable option for fielding a tactical round by FY11, and it was no longer requesting funding for BTERM. Navy officials state a competition could still occur in 2011 for ERM production.

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