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The Extended Range Guided Munition was a precision guided rocket-assisted 5-inch (127 mm) Shell (projectile) development by Raytheon for the U.S. Navy. The program was cancelled in March 2008 after twelve years of development and over 600 million dollars in funding.〔(Navy ends ERGM funding - Navy Times )〕 The developmental round was designated EX 171.〔(Raytheon ERGM (5" Projectile MK 171) - Designation Systems )〕 ERGM consisted of three major subsections; propulsion (rocket motor), warhead, and Guidance, Navigation and Control section. ERGM is fired from the 5 inch 62 Caliber Mark 45 gun Mod 4 at which point the fins deploy, rocket motor would ignite and lift the munition to at least 80,000 feet (24 km) when the canards would deploy and guide the ERGM to the target based on GPS guidance. It was to be used on Arleigh Burke class destroyers (hulls DDG-51 through 112). Despite the long development time the ERGM never worked as reliably as the older but significantly less expensive laser guided M712 Copperhead. During development, the ERGM failed several tests in which the tail fins failed to deploy at launch, rocket motors did not ignite, or the electronic components did not survive the stress of being shot from a deck gun.〔(Guided munition may be canceled - Navy Times )〕 In February 2008, guidance components, rocket motors, and tail fins all failed in tests; Raytheon claimed they were testing specific functionalities rather than overall functionality and that they were "on the verge" of making the whole system operate reliably, but the Navy had lost confidence after years of issues and were no longer getting a return on investment. Rising cost was another factor in cancellation. The unit cost of the shell more than tripled, from $45,000 in 1997 to $191,000 by 2006 (in contrast the Copperhead average unit production price was about $30,000), reducing the projected buy from 8,500 to about 3,150. Program research-and-development costs had increased from $80 million to $400 million between 1997 and 2004, with total program costs going from $400 million $600 million. The Navy formally cancelled the ERGM program on 19 March 2008.〔(End of ERGM spotlights other future guns - Navy Times )〕 BTERM was another U.S. Navy developmental round that included GPS guidance in an artillery shell; it too was terminated in 2008 after 4+ years of development by ATK. ==Specifications== * Caliber: 127 mm (5 in) * Length: 1.55 m (5 ft 1 in) * Weight: 50 kg (110 lb) * Speed: >3000 km/h (1860 mph) * Range: 110 km (60 nm) * Guidance: GPS/INS * Accuracy: < 20 m CEP independent of range. * Propulsion: Solid-propellant rocket motor. * Warhead: 72 DPICM submunitions (EX 1) or unitary high-explosive. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Extended Range Guided Munition」の詳細全文を読む スポンサード リンク
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