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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