The Rolls-Royce Meteor Engine

To understand why the Meteor was needed, its important to understand Britain’s tank doctrine before World War II. It was believed three types of tank would be most effective; infantry, light, and cruiser tanks.

Infantry tanks were slow and heavily armoured, with powerful offensive abilities. Light tanks were fast, thin armoured and often armed with small calibre machine guns. Cruiser tanks had sufficient armour and firepower, while being more mobile than the infantry tanks.

Troops advance alongside a Churchill MkIII infantry tank in Normandy, 1944.

In an attack, the infantry tanks would advance at walking pace with the infantry, absorbing incoming fire and providing cover for the troops. Once they had broken through the enemy’s position, the light and cruiser tanks would rush through with their speed and wreak havoc behind the enemy’s lines.

The First Cruisers

The first cruisers arrived in 1938 as the Cruiser Tank Mark I. The cruisers needed to be fast, but the Cruiser Mk I was only capable of 25 mph on road, and 15 mph off road. It used 9.4 L 150 hp engine. The next vehicle, the better armoured Cruiser Mark II could only reach 15 mph on road, and 8 mph off.

Britain’s first dedicated cruiser, the the Cruiser Tank Mark I.

Come 1940, and the cruiser line had reached the Cruiser Mark III. This tank was powered by the 340 hp Nuffield Liberty engine, a 27.0 L V12. This gave it an improved speed of 25 mph off road, but the armour was still very thin.

The Liberty V12 engine dated from the later days of WW1.

Around this time, British car maker Rolls-Royce had set up a team led by W.A. Robotham (an executive in the automobile division) to collect V12 Merlin engines and their parts from crashed aircraft.

Due to the extreme quality, performance and reliability required for aircraft components, these engines could not be re-used in this role, but Rolls-Royce hoped they would find a use at some point.

Early Meteor engines were often sourced from crashed aircraft, like this Avro Lancaster bomber with four Merlin engines.

1941 saw the introduction of the Cruiser Mark VI Crusader. This vehicle had improved armour, but with the same engine as the Mk III the mobility suffered. The Crusader was adequate in combat, but ultimately was an outdated design. The Liberty V12 was over stressed and caused continuous reliability issues.

The Cruiser Mark VI Crusader powered by the Liberty V12.

The Crusader’s replacement was already being designed in 1941, as the Cromwell tank.

British experience with these under powered vehicles made one thing very clear: more horsepower was needed.

The Beginning of the Meteor

In 1940, there were talks between Rolls-Royce and tank manufacturer Leyland about tank power plants. These talks lead to the idea of placing one of Robotham’s recovered Merlin engines into a tank for testing purposes.

In 1941, a refurbished 1000 hp Mark III Merlin had its supercharger and propeller reduction gear removed, and engine rotation reversed. It was placed inside a Crusader tank to assess performance, tank component stresses, and engine cooling, amongst other things.

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Now producing between 550-600 hp, the Merlin was almost double the horsepower of the Crusaders previous Liberty engine, but with the same 27.0 L displacement. The Crusader was so fast, the testing team struggled to accurately record its maximum speed, which was an estimated 50 mph.

This successful test meant an order was immediately placed for more engines, now called the Meteor.

The Meteor engine

However, the massive horsepower increase pushed the Crusaders drive train to its limits, requiring major redesigns if this tank was to use this engine. Instead, efforts were focused on incorporating the Meteor into the Cromwell, the Crusader’s replacement that was still on the drawing board.

Building enough Meteors was the engine’s biggest issue; Rolls-Royce didn’t have the capacity as the Merlin was considered a far higher priority. So, Rover began producing Meteors in 1942 in preparation for the Cromwell.

The A27 Cromwell

The Meteor’s Design

The production Meteor differed from the Merlin in numerous ways. This includes: removing the supercharger, reversing the engine’s direction of rotation to match that of automotive gearboxes, converting the engine from high octane aviation fuel to ordinary fuel, removing the aircraft propeller reduction gear, and changing the forged pistons to cast ones.

Many components were parts that were rejected by the Merlin’s strict quality control, as tolerances in ground based applications were much looser.

A Merlin 35, with the propeller reduction gearbox on the left, and the supercharger out of site at the back of the engine.

The production Meteor had around 600 hp, and a monstrous 1,450 lb ft of torque.

The Meteor In Service

The Cromwell was heavily delayed, partly due to the lack of Meteor engines, finally arriving in 1944 in time for D-Day. Despite having much thicker armour than previous cruiser tanks, the Cromwell could comfortably reach 40 mph. This would eventually be limited to 32 mph, as the incredible speeds the Cromwell could reach could actually damage the vehicle on rough terrain, and lead to excessive wear on the drive train.

The Meteor was so under stressed, it provided this performance even though it was limited to 2,250 rpm. This unstrained engine was very reliable in service.

The Meteor finally gave Britain not only a good tank engine, but a world class one.

The Cromwell would, like its predecessors, quickly become obsolete, but this time it wasn’t by fault of its engine.

The next vehicle to use this engine was the Comet, a vastly improved version of the Cromwell. It was 5 tonnes heavier, yet still could comfortably reach 32 mph.

The Meteor powered A34 Comet, regarded as Britain’s best tank of the war.

Post War Use

The Comet led to the worlds first main battle tank in 1946, the Centurion. The Centurion is widely considered to be one of the greatest tank designs in history, and it was powered by the Meteor engine.

The engine began to meet its match in the Conqueror, introduced in 1955. Even though it was up rated to 810 hp, it struggled to get the 64 tonne tank much past 20 mph.

The FV 214 Conqueror was one of the heaviest tanks Britain has fielded.

The Meteor engine was massively successful, being used in eight British tanks. The engine ironically out lived the Merlin from which it was derived, still being produced up until 1964, 8 years longer than the Merlin.

Another One From Us: Making a Merlin Engine Part 1

Rolls-Royce’s original V12 design from the 1930s played a significant part for the allies in the defeat of the Nazi war machine, being used in aircraft like the Spitfire and P-51 Mustang, and tanks on the ground like the Cromwell and Comet. For these reasons the Merlin and Meteor engines are regarded as some of the most successful military power plants ever used.