The Rolls-Royce Meteor and later the Rover Meteor was a British tank engine developed during the Second World War. It was used in British tanks up to 1964. It was a result of co-operation between Leyland Motors and Rolls-Royce who between them in 1941 had suggested that a specialised de-rated version of the latter company's Merlin aero-engine would be highly suitable for use in armoured fighting vehicles.
The Directorate of Tank Design (DTD), on 27 April 1941, supported production of the Meteor, eventually placing orders direct with Rolls-Royce to maintain development in connection with the Cromwell tank. A new tank specification, A27M, was produced for design of the Meteor-powered tank. The Meteor engine went on to become one of the most successful British tank engines.
Development started with the use of recovered Merlin engine parts from crashed aircraft. While unsuitable for re-use in aircraft, the Rolls-Royce chassis division had begun collecting and refurbishing them in the hopes of finding a use. Robotham was approached by Henry Spurrier of Leyland Mechanization and Aero, to ask about help with tank powerplants. Based on Spurrier's requirement, the first prototype Meteor engine (and subsequent production of Mark 1 engines) was assembled on the basis of recovered Merlin parts.
The major change for tank use was reversing the direction of engine rotation. Automotive gearboxes ran the opposite way to an aircraft propeller and changing direction required modification of the camshaft lobes. The Merlin had its supercharger, reduction gear and other equipment removed from its crankshaft, greatly simplifying its construction. The dimensions were now similar to the Nuffield Liberty engine and it would fit into the Liberty Mark VI version in the Crusader tank. The Merlin's dual ignition system was retained, each cylinder possessing two sparking plugs each driven from separate magnetos.
Changes were made to the Cromwell tank development programme to accommodate the new engine. To enable fitting in-line with a Merrit-Brown gear (and steering) box, the engine was lowered. A new flat sump was created, the oil pumps changed and the crankshaft could now line up with the new gearbox. Many of the aircraft specific parts of the engine were deleted, such as the propeller reduction gear and the aircraft-style starter. The new engine had cast, rather than forged, pistons and was de-rated to around 600 bhp (447 kW), running on lower-octane pool petrol instead of high-octane aviation fuel. British Thomson-Houston (BTH) Magnetos were changed for Simms units.
The engine, and the Rolls-Royce team's fresh look at tank development, had a major impact on British tank design. As development of the engine progressed, the Rolls Royce team became more and more involved in development of the tank. Despite his lack of experience in tank design or warfare, Robotham was made Chief Engineer of Tank Design and joined the Tank Board. He was involved in the Cruiser Mk VIII Challenger tank. The Rolls Royce chassis division, which had commenced the Meteor design, evolved into its Tank Division at Belper and was involved with the overall design of four versions of the Cromwell tank, using a standard set of components.
Early prototypes were produced by Rolls Royce. In 1941, Leyland, which had an order for 1,200 Meteor engines, was still advocating its own diesel tank engine for the Cromwell tank. It would deliver only 350 hp (260 kW), but it was concerned with the problem of sufficient cooling for the Meteor within the confines of the tank engine bay. When Leyland withdrew its support, Robotham took the problem to Ernest Hives. Hives took the problem to the Ministry of Supply, telling Lord Beaverbrook that he already had his hands full making Merlin aero engines, and Rolls-Royce would want £1 million to its credit and 'no interference' to make tank engines, Beaverbrook telegrammed back,
The British Government has given you an open credit of one million pounds. This is a certificate of character and reputation without precedent or equal. Beaverbrook
The Meteor was initially produced by Rolls-Royce but manufacturing capacity was severely limited due to the demand for Merlin engines. Early units were still manufactured using recovered Merlin parts and many early Meteors still showed crash damage. When engine manufacturing needed to increase output, brand new engines had to be made. Because weight saving was not so important for a tank engine, some of the Merlin's more expensive light-alloy components were replaced with cheaper, steel versions. It was also envisaged that the Meteor would use some components rejected on quality grounds for the Merlin, i.e. Merlin scrap. Many of these rejected parts while not meeting strict standards for airworthiness, were perfectly adequate for use in ground vehicles where the crew or operators were not subject to the inherent hazards involved in flight.
Rolls-Royce was also aiding the development of production jet engines at Rover, but progress there was slow and Rover became disillusioned. Hives struck a deal in December 1942 with Spencer Wilks of Rover to trade W.2B/23 production at Barnoldswick for the Rolls-Royce tank engine factory in Nottingham and production of the Meteor, to become officially effective on 1 April 1943. In 1943, an acute shortage of blocks was met by dismantling surplus older marks of Merlin.
Previously British tanks had been regarded as underpowered and unreliable and the Meteor is considered to be the engine that, for the first time, gave British tanks ample, reliable power. Replacing the earlier Liberty L-12 licence-built by Nuffield and used in the Crusader, the Meteor engine in the Cromwell tank provided almost twice the performance in virtually the same 1,650-cubic-inch (27.0 l) displacement. Reliability was significantly improved against previous tank engines. From its R-R Merlin origins, the Meteor was very lightly stressed and reliable. With the introduction of the Meteor engine in the Cromwell, originally intended for the 340 horsepower (250 kW) Liberty, the boost to 550 horsepower (410 kW) gave the vehicle exceptional mobility and speed. This increase in power made it possible to integrate greater armour on following tanks. Designers and military planners started to consider the possibility of a Universal tank, able to undertake both high-armour (Infantry tank) and high-mobility (Cruiser tank) roles. Ultimately, this resulted in the Centurion tank and evolved into the main battle tank concept.
The Meteor was used in the following vehicles:
-Avenger, a reworked design of Challenger for use as self-propelled artillery.
-Tortoise experimental assault tank.
-Caernarvon, used to train crews for Conqueror
-Conqueror post war heavy tank
The Meteor was also used as the propulsion for the experimental Helmore Projector, later known as the Helmover, a 30ft long remote controlled torpedo. It never reached deployment before the end of the war.