subclass_of napier rapier
The ___MASK95___ is a British air - cooled four - cylinder in - line ___MASK10___ designed by Frank Halford in 1927 to replace the ADC Cirrus in the de Havilland DH . 60 Moth light biplane . Initially developed as an upright 5 litre ( 300 cubic inch ) capacity engine , later versions were designed to run inverted with increased capacity and power . An ___MASK10___ is the component of the propulsion system for an aircraft that generates mechanical power . Aircraft engines are almost always either lightweight piston engines or gas turbines , except for small multicopter UAVs which are almost always electric aircraft . De Havilland ___MASK97___ ___MASK13___ Limited was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of north London . Operations were later moved to Hatfield in Hertfordshire . The Napier Rapier was a British 16 - cylinder H pattern air - cooled aero ___MASK6___ designed by Frank Halford and built by Napier & Son shortly before WWII . Major Frank Bernard Halford CBE FRAeS ( 7 ___MASK93___ 1894  16 April 1955 ) was an ___MASK87___ ___MASK10___ designer . He is best known for the series of de Havilland Gipsy engines , widely used by light aircraft in the 1920s and 30 ' s .