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The BM-21"Grad" () launch vehicle ((ロシア語:БМ-21 "Град")), (Grad) a Soviet truck-mounted 122 mm multiple rocket launcher,〔(Splav 122 mm BM-21 multiple rocket launcher family (Russian Federation), Multiple rocket launchers ), Jane's Armour and Artillery〕 and a M-21OF rocket〔(122 mm BM-21 Grad-series rockets (Russian Federation), Artillery rockets ), Jane's Ammunition Handbook〕 were developed in the early 1960s. ''BM'' stands for ''boyevaya mashina'' (combat vehicle), and the nickname means "hail". The complete system with the BM-21 launch vehicle and the M-21OF rocket is designated as the M-21 Field Rocket System. The complete system is more commonly known as a Grad multiple rocket launcher system. In NATO countries, the system (either the complete system or the launch vehicle only) was initially known as M1964. Several other countries have copied it or developed similar systems. == Description == The M-21 Field Rocket Systems with a BM-21 launch vehicle (122 mm multiple rocket launcher (MRL) system entered service with the Soviet Army in 1963 to replace the ageing 140 mm BM-14 system). The launch vehicle consists of a Ural-375D six-by-six truck chassis fitted with a bank of 40 launch tubes arranged in a rectangular shape that can be turned away from the unprotected cab. The vehicle is powered by a water-cooled V-8 180 hp gasoline engine, has a maximum road speed of , road range of up to , and can cross fords up to deep. The original vehicle together with supporting equipment (including the re-supply truck 9T254 with 60 rockets) is referred to by the GRAU index 9K51; the launcher itself has the industrial index of 2B5. In 1976, the BM-21 was mounted on the newer Ural-4320 six-by-six army truck. The three-man crew can emplace the system and have it ready to fire in three minutes. The crew can fire the rockets from the cab or from a trigger at the end of a cable. All 40 rockets can be away in as little as 20 seconds, but can also be fired individually or in small groups in several-second intervals. A PG-1M panoramic telescope with K-1 collimator can be used for sighting. The BM-21 can be packed up and ready to move in two minutes, which can be necessary when engaged by counter-battery fire. Reloading is done manually and takes about 10 minutes. Each rocket is slowly spun by rifling in its tube as it exits, which along with its primary fin stabilization keeps it on course. Rockets armed with high explosive/fragmentation, incendiary, or chemical warheads can be fired . Newer high explosive and cargo (used to deliver anti-personnel or antitank mines) rockets have a range of and more. Warheads weigh around , depending on the type. The number of rockets that each vehicle is able to quickly bring to bear on an enemy target makes it effective, especially at shorter ranges. One battalion of eighteen launchers is able to deliver 720 rockets in a single volley. The system has lower precision than classical artillery and cannot be used in situations that call for pinpoint precision. It relies on a large number of shells dissipating over an area for a certain hit rate on specific targets. Nonetheless, because of the short warning time for the impact of the whole volley, the BM-21 is still considered a fearsome weapon today. 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「BM-21 Grad」の詳細全文を読む スポンサード リンク
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