Rolls-Royce Merlin The Rolls-Royce Merlin is a British-designed V-12 piston aero engine with a liquid cooling system. It was designed by Rolls-Royce as a private venture using experience from their previous Kestrel and Schneider Trophy engines. The engine was first run in 1933 and flew in a Hawker biplane fighter producing 740 hp. Several new aircraft…