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The Hedgehog (also known as an ''Anti-Submarine Projector'') was a forward-throwing anti-submarine weapon that was used during the Battle of the Atlantic in the Second World War. The device, which was developed by the Royal Navy, fired up to 24 spigot mortars ahead of a ship when attacking a U Boat. It was deployed on convoy escort warships such as destroyers and corvettes to supplement the depth charges. As the mortar projectiles employed contact fuzes rather than time or barometric (depth) fuzes, detonation always occurred directly against the hull of a submarine making it more deadly than depth charges which relied on damage caused by hydrostatic shockwaves. Statistics show that in WWII out of 5,174 British depth charge attacks there were 85.5 kills: a ratio of 60.5 to 1. In comparison, the Hedgehog made 268 attacks for 47 kills: a ratio of 5.7 to 1.〔(【引用サイトリンク】title=Britain ASW Weapons )〕 ==Development== The "Hedgehog", so named because the empty rows of its launcher spigots resembled the spines of a hedgehog, was a replacement to the unsuccessful Fairlie Mortar that was trialled aboard HMS ''Whitehall'' (D94) in 1941. Although a failure, the Fairlie was designed to fire depth charges ahead of a ship when attacking a submarine. This principle of forward-firing projectiles was considered viable. It was from this, secret research undertaken by the Directorate of Miscellaneous Weapons Development (DMWD) led to the development of the Hedgehog. The weapon was a multiple 'spigot mortar' or spigot discharger, a type of weapon developed between the wars by Lieutenant Colonel Stewart Blacker, RA. The spigot mortar was based on early infantry trench mortars. The spigot design allowed a single device to fire warheads of varying size. The propelling charge was part of the main weapon and worked against a rod (the spigot) set in the baseplate which fitted inside a tubular tail of the 'bomb'. This principle was first used on the Blacker Bombard 29mm Spigot Mortar and the later PIAT anti-tank weapon. The adaptation of the bombard for naval use was made in partnership with MIR(c) under Major Millis Jefferis who had taken Blacker's design and brought it into use with Army. The weapon fires a salvo of 24 bombs in an arc, aimed to land in a circular or elliptical area about 100 feet (30 m) in diameter at a fixed point about 250 yards (230 m) directly ahead of the attacking ship. The mounting initially was fixed but was later replaced by a gyro-stabilised one to allow for the rolling and pitching of the attacking ship. The system was developed to solve the problem of the target submarine disappearing from the attacking ships ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the 'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar - the so-called 'Instantaneous echo', where the output sound pulse and returning echo merge. This 'blind spot' allowed the submarine to make evasive manoeuvres undetected while the ship was still out of range for depth charge attack, the submarine being effectively invisible to the sonar as the ship came within the sonar's minimum range. The solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range. 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「Hedgehog (weapon)」の詳細全文を読む スポンサード リンク
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