ADC Cirrus and Cirrus-Hermes are British aero engines of the mid-1920s. Sometimes known as the Blackburn Cirrus, examples remain airworthy today. [1 ]
Design and development [ edit ]
ADC Cirrus engines were originally built by ADC Aircraft until Cirrus Aero Engines Limited was formed in 1927. The company became Cirrus-Hermes in 1931 when it was bought by the Cirrus-Hermes Engineering Company and later became the Cirrus Engine Section of Blackburn & General Aircraft Limited in 1934, and operated as a separate division until production ended in the post- World War II era. [2 ]
Cirrus's first product was the 90 hp (67 kW) Cirrus I, which passed its 50 hour type rating in 1925. It was the first air-cooled inline engine, a design by
Frank Halford that proved extremely popular for light aircraft. The basic layout (using one cylinder bank of an ADC Airdisco V-8 engine) was quickly copied by a number of other manufacturers. Later versions named the Cirrus II, and Cirrus III were produced each with slightly greater displacement, and power (Cirrus II - 85 hp, Cirrus III - 90 hp). [3 ]
The next model line, Cirrus-Hermes I, II, and IV were produced ranging in power from 105 hp to 140 hp depending on type. The later Cirrus engines were designed to run inverted.
Variants [ edit ]
A comparison of Cirrus Hermes I (left) and Cirrus III (right)
Cirrus-Hermes IIB (inverted)
(1929) Inverted engine
Cirrus-Hermes I engine in Roe IV replica, Shuttleworth collection
Applications [ edit ]
List from Lumsden. [5 ] [6 ]
Cirrus-Hermes [ edit ]
Engines on display [ edit ]
Specifications (Cirrus I) [ edit ]
Data from Lumsden. [2 ]
Type: Inline, air-cooled, upright 4-cylinder piston engine
Bore: 4.13 in (105 mm)
Stroke: 5.12 in (130 mm)
Displacement: 274.36 cu in (4.5 L)
Length: 45.8 in (116.3 cm)
Width: 18.26 in (46.4 cm)
Height: 34.3 in (87.1 cm)
Dry weight: lb ( kg)
1 inlet and 1 exhaust valve per cylinder Valvetrain:
Fuel system: 1 Claudel carburettor
Fuel type: 70 octane
Cooling system: air
See also [ edit ]
References [ edit ]
^ This name applies only to the revised range of Cirrus engines produced after 1934 by Blackburn, e.g. the Blackburn Cirrus Major.
^ a b Lumsden 2003, p. 130.
^ Gunston 1989, p. 40.
^ Lumsden 2003, p.132.
^ Lumsden 2003, pp. 130-132.
^ Cirrus engines may not be the main powerplant for these aircraft types (test installations are included).
^ Wesselink 1982 p.80
^ Wesselink 1982 p.81
Bibliography [ edit ]
World Encyclopaedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9 Lumsden, Alec.
British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.
Wesselink, Theo; Postma, Thijs (1982). De Nederlandse vliegtuigen. Haarlem: Romem. ISBN 90 228 3792 0.
External links [ edit ]