The Bristol Aeroplane Company of Bristol, United Kingdom was one of the great pioneer aeronautical companies. Both Bristol aircraft and engines are very well known and will not be discussed here. Mr. A.H.R. (later Sir Roy) Fedden was their chief engine designer. In the mid-1920s, Bristol built a family of small, two-cylinder HOAEs for the light-aeroplane competitions held in the UK. These engines were also used extensively in the US. It has been reported (AI1/74) that in the 1930s, Fedden suggested an HOAE-powered variation of the Bristol Type 153A twin-engine fighter design to meet the UK Air Ministry Specification F.37/35. Fedden's idea was that he would develop a new sleeve-valve HOAE to be completely submerged within the thick wing of the Type 153A. The submission was not accepted and the Specification was implemented as the Westland Whirlwind with two Rolls-Royce Peregrine V-12 engines. After WWII, Fedden formed his own company and pursued the submerged-wing engine installation idea by developing air-cooled, sleeve-valve HOAEs developing 160-185hp, see Fedden.
O-67 -- {3.346 / 3.799 / 66.8} / {85 / 96.5 / 1095}
Same stroke as O-75.
2cyl; Cherub Series I; 25hp@2500rpm; 1923-1927; Wt = 90#.
2cyl; Cherub Series II; 34hp@4000rpm; 1923-1927; Wt = 108#.
As Cherub Series I except geared to 0.5; had reliability difficulties.
Ae39; AJJ1, 2; AM; BGE; S.
Applications: (UK) Avro 562 Avis [G-EBKP] - see AM8/85; Short S.4 Satellite [G-EBJU] - see AM11/85; Vickers Type 98 Vagabond [G-EBJF] - see AM12/85.
O-75 -- {3.543 / 3.799 / 74.9} / {90 / 96.5 / 1228}
Same stroke as O-67.
2cyl; Cherub Series III; 32hp@2900rpm, 36@3200 (TO); 1925-1927; Wt = 100#.
Originally a single-ignition engine with dual plugs; later a dual-ignition engine.
aerofiles.com; Ae39; AJJ1, 2; AM; AW; BGE; J1; S; U&C.
Applications: (France) Mignet HM-14 Pou du Ciel [G-ADSE]. (Germany) Messerschmitt M-17 (1925 original and a modern replica [D-ERTA] now flying with the same Cherub III) - see AM8/04. (UK) ANEC II [G-EBJO] - see AM6/85; B.A.C. Drone [G-ADPJ, 'EDB] - see AM 10/76; Beardmore W.B. XXIV Wee Bee I [G-EBJJ, later VH-URJ] - see AM5/85; Bristol Type 91, 91A, 91B Brownie [G-EBJK, 'JL, 'JM] - see AM7/85; Cranwell C.L.A.3 [G-EBMC] - see AM8/80, Cranwell C.L.A.4 [G-EBPC] - see AM12/78, C.L.A.4A [G-EBPB] - see AM12/78; Dart Pup (modified) [G-AELR] - see AM 7/77; de Bruyne-Maas (Aero Research) Ladybird [G-AFEG]; de Havilland D.H.53 Humming Bird [J7326 which became G-EBQP, G-EBXN] - see AM4/85; Halton H.A.C. I Mayfly [G-EBOO], H.A.C. II Minus [G-EBOO]; Hawker Cygnet [G-EBJH, 'MB] - see AM10/85; Luton Minor [G-AMAW]; Martin Monoplane [G-AEYY]; Parnall Pixie III [G-EBJG, 'KK] - see AM10/80, Pixie IIIA [G-EBJG] - see AM10/80; R.A.E. Hurricane [G-EBHS] - see AM12/84, Scarab [G-EBOH]; Supermarine Sparrow II [G-EBJP] - see AM9/85; Westland Woodpigeon I [G-EBIY] - see AM4/86. (US) Ford-Stout Dragonfly; Heath 115 Special, Baby Bullet (Bluebird), CA-1 Parasol, Tomboy; Johnson Twin 60; Meyers Midget; Powell PH Racer.