|
| |
The Rolls-Royce Merlin
From: Science Museum
| By:
Andrew Nahum |
EDITOR'S INTRODUCTION |
The Merlin, probably the only aero engine ever to become a household name, was developed in the early 1930s by Rolls-Royce, a company with a long history of designing world class automobiles and aero engines. It was used to power both Hurricane and Spitfire fighter planes during the Second World War and is best remembered for its role in the Battle of Britain. Andrew Nahum of the Science Museum, London, tells the story of the engine which helped the Allies to win the war. |
  he Merlin is uniquely famous. Perhaps the only aero engine to be widely known by name, it represented the contemporary pinnacle of engineering design and production skill. During the Battle of Britain the Merlin powered both types of defending fighters, the Hurricanes and Spitfires. In 1940 few were aware that the Merlin came from a long line of Rolls-Royce engines bearing names of birds of prey. Then the resonances were Arthurian, speaking of magic and power--an engineering magic which only Rolls-Royce could create. |
 Rolls-Royce had been drawn into the aero engine business at the government's request during the First World War. At first Britain had almost no aero engine industry and aircraft were equipped with imported French engines or with engines licence-built from French designs. Rolls-Royce undertook the manufacture of some of these types but regarded them as defective. Henry Royce therefore began work on an engine of his own that came to be known as the Eagle. |
This was a 200 horsepower water-cooled engine with 12 cylinders in 'V' formation. Shortly after the war the dependability of these Rolls-Royce engines was demonstrated in a dramatic way by the first crossing of the Atlantic by Alcock and Brown in a Vickers Vimy aircraft powered by two Eagles. |
The experience of designing the Eagle passed into the ethos of the company. The directors even compiled the letters and memoranda from Royce concerning development of the engine into a book, The First Aero Engine made by Rolls-Royce Limited, 'as an example to all grades of Rolls-Royce Engineers, present and future.' |
In the inter-war period the Air Ministry sustained three aero engine firms, sometimes referred to as 'The Family', by a considered rationing of contracts. Bristol manufactured high-powered air-cooled radial engines, favoured for the emerging airlines; Armstrong-Siddeley also manufactured radials, though of less developed design, which were used in RAF training aircraft and in many military aircraft sold for export; Rolls-Royce built water-cooled in-line engines, chosen by aircraft designers for the clean aerodynamic nose they allowed on high-speed fighters. |
By the late 1920s the Eagle had been replaced by the Kestrel--a 21 litre V-12 unit giving nearly 500 horsepower--which was fitted into the most modern fighters flown by the RAF. Curiously it was a Kestrel which was used for the first flights of both the prototype Messerschmitt 109 and the Junkers Ju 87 (Stuka) in 1935, before appropriate German engines were ready. |
In this period Rolls-Royce also produced the 2,000 horsepower 'R' racing engines which achieved notable success in the Schneider Trophy races. |
 The Merlin, fruit of all this piston engine experience, was drawn up first in 1932. It was intended to develop 750 horsepower with the possibility of development to give 1,000 horsepower. Again, it used V-12 layout and had a capacity of 27 litres. It first flew in 1935. Later that year a Merlin powered the prototype Hawker Hurricane for its first flight and in March 1936 powered the first Spitfire. Throughout the ensuing war the Merlin was to undergo extraordinary development and almost every night throughout the war, the 'Derby Hum'--the drone of engines on the test beds--lay over the city. Power more than doubled over five years, mainly through ever-improving supercharger design, reaching well over 2,000 horsepower. The Merlin was also the subject of a major industrial effort with over 150,000 examples being produced by Rolls-Royce at Derby, Crewe and Glasgow, by the Ford Motor Company in Manchester and by Packard in the United States. |
But the Merlin will always be best remembered  for its role in the Battle of Britain, for this was a contest between engines as much as between aircraft. No other engine made anywhere in the world at the time could have given the Spitfires and Hurricanes the power and stamina to meet the Daimler-Benz powered Messerschmitts. |
Both at the time and looking back over 50 years this battle is seen as one of the pivotal military contests in human history. It was the first check inflicted on German arms during the Second World War and as a result the United Kingdom survived to be the base for the Anglo-American assault on the Second Front. Modern Europe was born in 1940 over the fields of Kent. After the war, Lord Tedder, Marshal of the Royal Air Force, who had been in charge of the development of aircraft and engines during the period of the battle, attributed the British victory to three predominant factors: the skill and bravery of the pilots, 100-octane fuel, and the Rolls-Royce Merlin engine. There can hardly be a more powerful testimony to the social and human impact of engineering. |
|
| |
