ADC Cirrus

Cirrus
ADC Cirrus II at the Science Museum, London
Type Air-cooled 4-cylinder inline piston engine
National origin United Kingdom
Manufacturer Aircraft Disposal Company, Cirrus Aero-Engines Limited
First run 1925
Major applications de Havilland DH.60 Moth
Avro Avian



The ADC Cirrus and Cirrus-Hermes are British aero engines of the mid-1920s. Sometimes known as the Blackburn Cirrus,[1] examples remain airworthy today.

Design and development

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)[3] 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).

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.[4]

Variants

A comparison of Cirrus Hermes I (left) and Cirrus III (right)
Cirrus I
(1925)
Cirrus II
(1926)
Cirrus III
(1929)
Cirrus IIIA
(1933)
Cirrus-Hermes I
(1929)
Cirrus-Hermes II
(1930)
Cirrus-Hermes IIB (inverted)
(1931)
Cirrus-Hermes IV
(1930)
Cirrus-Hermes IVA
(1929) Inverted engine
Cirrus-Hermes I engine in Roe IV replica, Shuttleworth collection

Applications

List from Lumsden.[5][6]

Cirrus

Cirrus-Hermes

Engines on display

A Cirrus Hermes

Specifications (Cirrus I)

Cirrus III fitted to a de Havilland DH.60 Moth

Data from Lumsden.[2]

General characteristics

Components

Performance

See also

Related development
Comparable engines
Related lists

References

Notes

  1. This name applies only to the revised range of Cirrus engines produced after 1934 by Blackburn, e.g. the Blackburn Cirrus Major.
  2. 1 2 Lumsden 2003, p. 130.
  3. Gunston 1989, p. 40.
  4. Lumsden 2003, p.132.
  5. Lumsden 2003, pp. 130-132.
  6. Cirrus engines may not be the main powerplant for these aircraft types (test installations are included).
  7. Wesselink 1982 p.80
  8. Wesselink 1982 p.81

Bibliography

  • Gunston, Bill. 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.

External links

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