The Napier Sabre is a British H-24-cylinder, liquid-cooled, piston engine, designed by Major Frank Halford and built by D. Napier & Son during World War II. It was one of the most powerful inline piston aircraft engines in the world, developing from 2,200 hp in its earlier versions to 3,500 hp in late-model prototypes. It powered several aircraft, such as the Hawker Typhoon, Hawker Tempest, Blackburn Firebrand, Martin-Baker MB 3, and a Hawker Fury prototype. The engine used a complex sleeve valve design, which reduced the airflow resistance and allowed higher compression ratios. However, the engine also suffered from reliability issues, cooling problems, and manufacturing difficulties, which limited its production and service life. The engine was eventually replaced by jet engines after the war.