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The Rolls-Royce Merlin, the engine that “won the Second World War”…

An airplane without an engine is nothing and even, any design of an airplane must go through the choice of an engine, an essential point on which a structure will then be built to meet a specification. During the Second World War, at the height of piston engines before the era of jet propulsion took over for military and commercial aviation, engine manufacturers were looking for all possible solutions to develop ever more power…

In this work, Gordon Wilson is interested in one of these engines, or rather in an engine which has known many derivatives over time. This is the Rolls-Royce Merlin. In the first part, he recounts the "birth of a legend" from 1904 to 1934. We thus discover the two characters whose names will be linked forever: Frederick Henry Royce and Charles Stewart Rolls. Nothing predestined these two men to meet, except the passion for cars. Their social conditions, their training separated them but they found themselves around the development of an engine to do better than the car manufacturers of the moment.

They surround themselves with other technicians. Both were obviously interested in fledgling aeronautics and at the start of the First World War the Rolls-Royce company received an order from the British government to produce a Renault V8 and aero engines for what would become the Royal Air Force. Here again, the creators of the company preferred to create their own engine, the Eagle, a liquid-cooled V12 which took to the air in December 1915. Many manufacturers retained this GMP which also made itself known by the first crossing of the North Atlantic in June 1919, with Alcock and Brown flying a Vickers Vimy.

The car manufacturer's aeronautical division will not stop there and will continue to design various engines – Hawk, Falcon, Condor, Eagle XVI, Kestrel, Goshawk, Buzzard… – including the one intended for a fighter project developed by Supermarine in early 1930s, a certain Spitfire. It is a liquid-cooled V12, with a reduced master torque with its 60° angle. Thus, the Merlin B develops 950 hp on bench in February 1933. The power increases to 1,030 in 1937 with the Merlin II installed on Spitfire and Hurricane.

After 90 pages on this historical part, and undoubtedly the most interesting because the least known, and the presentation of all the components of a piston engine, the author then moves on to the development of the Hurricane and Spitfire fighters then to the Battle of France and from England. The following chapters review, one by one and in detail, the different aircraft that have been equipped for certain models with a Merlin or a Packard: De Havilland Mosquito, Avro Lancaster, North American Mustang (which will go from the Allison to the Packard V-1650 licensed version of the Rolls-Royce Merlin). A chapter quickly regroups other Merlin-powered aircraft: Whitworth Whitley, Avro Lincoln, Avro Tudor, Avro York, Bouton-Paul Defiant, Curtiss Warhawk, De Havilland Hornet and Sea Hornet, Fairey Barracuda, Battle and Fulmar, Hawker Sea Hurricane, Westland Welkin, Vickers Wellington – throw away no more…

It takes 8 pages and a few tables to discuss the evolution of the concept from the original PV12 to the ultimate Merlin 620, including the Merlin II, 21, 64 and many others. Even if the Merlin was overtaken in power at the end of the war by other English engines – such as the 24-cylinder Napier Saber – it survived the war, bringing its performance and reliability. Hence the subtitle of the book, which seems well chosen, “the engine that won the Second World War”. The Merlin can be described as the most significant piston engine of the 1940s…

A final chapter evokes the recent past, with in particular the Battle of Britain Memorial Flight, which still uses Merlin on a daily basis, a few museums and also the Californian company Vintage V12, which specializes in revisions of Merlin for wealthy collectors. All in all, a very British book on a British engine.

God save the Merlin! ♦♦♦

Photo © CC/Jaw

– The Merlin, by Gordon Wilson, Ed. Amberley. 258p. including a 16-page notebook of photos. €16.00 Text in English.

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