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The Tank, Cruiser, Mk V or A13 Covenanter was a British cruiser tank of the Second World War. The Covenanter was the first cruiser tank design to be given a name. Designed by the London, Midland and Scottish Railway as a better-armoured replacement for the Cruiser Mark IV, it was ordered into production in 1939 before pilot models were built. Problems with the design only became apparent after production was under way. The tank equipped various British armoured divisions in the home defence and training roles. It never left the British Isles as poor engine cooling made it unfit for use overseas in hot climates. In 1943 it was declared obsolete after more than 1,700 had been built. It was named after the Covenanters, a Scottish religious faction in the British Isles at the time of the Wars of the Three Kingdoms. ==Development== In 1938, the War Office had issued a requirement for a new, better armoured "heavy" cruiser tank to replace the Cruiser IV. Nuffield's A16 (and the A14) design was found to be too expensive, and in 1939 a cheaper and lighter cruiser tank - under General Staff specification A13 Mk III Cruiser Mark V - was chosen to be developed. It had nothing apart from Christie suspension in common with the other A13 specifications.〔Fletcher, ''The Great Tank Scandal'' p. 60〕 The initial specification required a QF 2 pounder gun, at least one machine gun, the same A13 Christie suspension in a lower hull, epicyclic steering transmission and "armour standard" of . The "30 mm armoured standard" referred to any vertical plate having to be 30 mm thick. Angled surfaces (through the principles of sloped armour) could be thinner, provided they were at least as effective as a 30 mm thick vertical plate. From these a design using many sloped surfaces was chosen to keep the weight low. To keep the silhouette low the suspension used cranked arms and a low profile engine was envisaged. The engine to specifically designed for it was to deliver at least . The Wilson transmission and steering of the A16 would be used.〔Fletcher and Sarson p4〕 Design work was by the London, Midland and Scottish Railway Company (LMS). They had no prior experience in the design and production of fighting vehicles,〔LMS was also involved in production of the Cruiser Mark III〕 they had been invited to participate under a Government policy that British companies should develop necessary skills in expectation of war.〔White, B T p. 47〕 The design assumed a welded hull rather than the usual rivetting. The turret was designed by Nuffield, with Henry Meadows designing a new low profile engine for it. On 17 April, before even a single prototype was produced, the first 100 vehicles were ordered from the LMSR. Additional orders soon followed, with English Electric and Leyland Motors joining the production effort, for a final production total of 1,771 Covenanters.〔(Tanks of World War II, Steve Crawford, Brown Partworks Ltd 2000, ISBN 0-7603-0936-1 ) (p 51)〕〔Bigham quotes 1,365 Covenanters〕 Nuffield was also approached, but preferred to design its own offspring of the A13 line, which became the Cruiser Mk.VI Crusader. Due to the expectations of an imminent war, the design was ordered "off the drawing board". The expectation was that two pilot models would serve for testing and results applied to the production lines. To meet the engine requirement, a horizontally opposed 12-cylinder design was used. Although flat, it was wide and left no room for radiators in the engine compartment, and so the radiators were situated at the front of the vehicle. The unusual arrangement, although tested in mockup form first, when combined with the rushed design process resulted in serious problems with engine cooling. Even when the systems were redesigned there were problems, and the piping from engine to the radiators heated the fighting compartment. These problems meant that the Covenanter would not be employed in the North African Campaign. Instead, Crusader and American tanks were sent to Africa, while the Covenanters remained in the British Isles. LMS advised a return to riveted construction due to doubts about its strength, and rather than risk delays due to a lack of welders, this was accepted. The welded design used two layers of armour plate, the inner being of steel that would weld readily without losing its properties. This two-plate system was retained when the design reverted to riveted construction. The use of riveted construction, the use of steel wheels instead of the intended aluminium〔Aluminium had become a priority material that was allocated to aircraft production.〕 and an increase in armour specification to at the front of hull and turret increased the weight to a level where the tank suspension was at maximum load, leaving no room for later development of the design.〔 A further change was made to the transmission. Rather than risk the availability of the combined Wilson transmission and steering affecting production, the A13 "crash" gear box was used with epicyclic steering units. This had the knock-on effect of a reduced size of cooling fan for the transmission compartment.〔Fletcher and Sarson p6〕 The contracts were placed with the manufacturers in 1939. The pilot model (with welded hull) was tested with a favourable outcome in 1940; though the second pilot had cooling issues. The first deliveries of production vehicles were not until after the battle of Dunkirk. Production of turrets lagged behind that of hulls. Although the Covenanter was needed at the time, production continued even when newer better tank designs were waiting for space on production lines.〔Fletcher p. 62〕 By late 1943 the Covenanter was considered too weakly armed and armoured to deal with new German tanks. It was decided that neither problem could be addressed without significant changes in the design, so the tank was declared obsolete and all vehicles except the bridgelayer variant were to be scrapped.〔〔Fletcher (1993) p. 43〕 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「Covenanter tank」の詳細全文を読む スポンサード リンク
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