The Napier Sabre is a liquid-cooled, twenty-four-cylinder aircraft engine with an H configuration and sleeve valves. Designed under Frank Halford, it became the powerplant of the Hawker Typhoon and several Tempest versions. Its high output was accompanied by difficult early development and production problems.[1]Development of the Napier Sabre engineInstitution of Mechanical Engineers · engineersatwar.ww2.imeche.org · Accessed 2026-09-13Open source details[2]Hawker TempestBAE Systems · baesystems.com · Accessed 2026-09-13Open source details
Layout and development
The Sabre drew on Napier's experience with the Dagger's opposed arrangement, but placed its cylinder blocks horizontally to accommodate sleeve valves. The sleeves controlled gas exchange through ports, replacing the conventional inlet and exhaust poppet valves. Halford's interest in this approach developed alongside Harry Ricardo's work on combustion and engine efficiency.[1]Development of the Napier Sabre engineInstitution of Mechanical Engineers · engineersatwar.ww2.imeche.org · Accessed 2026-09-13Open source details
The first Sabre was tested in 1938 at 1,350 hp. By June 1940 it passed an Air Ministry hundred-hour test at 2,200 hp. Manufacturing accurate sleeves proved difficult: loss of circularity contributed to seizures. Better production methods, including assistance from Bristol, helped improve reliability.[1]Development of the Napier Sabre engineInstitution of Mechanical Engineers · engineersatwar.ww2.imeche.org · Accessed 2026-09-13Open source details
Typhoon installation
The RAF Museum's Typhoon MN235 was built by Gloster in 1944 with a 2,180 hp Sabre IIA. Its preserved history records the aircraft's first flight on 8 February that year. This installation represents the production combination that carried the Sabre into the Typhoon's wartime fighter and ground-attack career.[3]Hawker Typhoon MN235 individual historyRAF Museum · rafmuseum.org.uk · Accessed 2026-09-13Open source details[1]Development of the Napier Sabre engineInstitution of Mechanical Engineers · engineersatwar.ww2.imeche.org · Accessed 2026-09-13Open source details
Tempest versions
The Tempest I prototype used the Sabre IV with wing radiators, but engine supply difficulties prevented production. The Tempest V instead used Sabre II-series engines and entered operational service in 1944. This placed the established engine in Hawker's redesigned, thinner-wing fighter.[2]Hawker TempestBAE Systems · baesystems.com · Accessed 2026-09-13Open source details
The later Tempest VI had a 2,340 hp Sabre V and a larger chin radiator. The changes show how the aircraft installation evolved with the engine: additional power also required attention to cooling arrangements. Experimental Tempest work included an annular radiator and a large ducted spinner.[2]Hawker TempestBAE Systems · baesystems.com · Accessed 2026-09-13Open source details