Rolls-Royce Merlin R.M. 14S.M. Mk 100 V-12 Engine, 1944. Creator: Rolls-Royce.

Formed in 1906 to produce automobiles, Rolls-Royce was asked to begin designing and building aircraft engines at the outbreak of World War I in 1914. Design of the Merlin began in 1933 following the similar Kestrel design. Early Merlin Mk II and Mk III engines, which produced about 7,457 kw (1,000 horsepower), powered Hawker Hurricanes and Supermarine Spitfires in the Battle of Britain. Engine improvements and progress in supercharger performance increased the Merlin's rated power to over 1,715 kW (2,300 horsepower) by the end of the war. This engine, a developmental prototype in the Merlin 100 series, was built by Rolls-Royce in Derby, England, sometime between June and July 1944. It was a new class of engine, built to higher performance standards for power and altitude. Merlin 100s powered the de Havilland Mosquito, Avro Tudor, and de Havilland Hornet and Sea Hornet. U.S. Packard-built Merlin 100s (V-1650-9 and -11) powered later versions of the North American Mustang.