Napier: Dagger
Note: This is a sub-section of Napier
1921 By an arrangement between the Air Ministry and de Havilland, Major Frank Halford, working as a consultant, designed the 16-cylinder air-cooled Rapier, and this was followed by the compact Napier-Halford Dagger engine, which had 24 cylinders in H-form (four banks of 6 inline cylinders).
The Dagger was intended to power a small, highly aerodynamic fighter aircraft. The intended size of the aircraft favoured the adoption of an air-cooled inline engine, and considerable effort was devoted to the ducting of cooling air. 24 cylinders, 1027 cu in (16.84 litres). It developed 635 HP in 1934, and was cleared for production in 1936, developing 1000 HP at the high speed of 4200 rpm. A version was bench-tested at 1500 HP. However, the fighter did not materialize, and the engine was misapplied to a bomber, the Handley Page H.P.53 Hereford .