Rolls-Royce Merlin engine, 1932.
© Science Museum / Science & Society Picture Library
Probably the only aero engine to be widely known by name, the Merlin was one of a series of Rolls-Royce engines named after birds of prey. Rolls Royce began making aero engines during World War I at the government's request. During the Battle of Britain it was used to power both of the defending fighters, Hurricanes and Spitfires. The Spitfire was integral to Britain's front-line air defence during World War II together with the Hawker Hurricane fighter.