ADC Cirrus

Design and development

The Cirrus engine originated in Geoffrey de Havilland's 1924 search for a powerplant suitable for the light two-seat sports biplane which would become the de Havilland Moth. No engine existed at the time with a suitable level of power combined with a low weight. The Aircraft Disposal Company, also known as Airdisco and ADC, were producing the low-cost Airdisco V8 which had been developed by Frank Halford from their large stocks of war surplus Renault V8 aero engines. De Havilland realised that half of this engine would make an air-cooled four-cylinder inline engine of just the right size at low cost. He persuaded Halford to undertake its design and development.

The cylinders, pistons, con-rods and gearing were taken from the Renault, with the valve gear based on the Airdisco, and a new five-bearing crankshaft and cast crankcase were designed. It became the first Cirrus engine, and the first air-cooled four-cylinder inline aero engine to go into quantity production.

The original Cirrus engines were all designed by Halford and built by ADC. The 65 hp Cirrus I passed its 50-hour type rating in 1925. De Havilland launched his product as the Cirrus Moth and it proved a winning combination. The engine was soon adopted for other aircraft. 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).

ADC ceased manufacture when it ran out of surplus Renault engines around 1928.

Subsequent manufacture

Main article: Cirrus aero engines

When ADC ran out of parts, manufacture of the Cirrus III was taken up by Cirrus Aero Engines, also based at Croydon.

The Cirrus III was also adapted and improved by American Cirrus Engines, who manufactured it under license.

Variants

;Cirrus I :(1925) ;Cirrus II :(1926) ;Cirrus III :(1929)

Applications

List from Lumsden except where noted. The list includes trial installations where a different engine was principally adopted.

Cirrus

Cirrus I

• Avro Avian
• Avro Baby
• de Havilland DH.60 Moth
• Short Mussel
• Westland Widgeon

Cirrus II

• Avro Avian
• de Havilland DH.60 Moth
• de Havilland DH.71 Tiger Moth
• Piaggio P.9
• Short Mussel
• Westland Widgeon
• Bloudek XV Lojze

Cirrus III

• Avro Avian
• Blackburn Bluebird
• Cierva C.17
• de Havilland DH.60 Moth
• de Havilland DH.71 Tiger Moth
• Dudley Watt D.W.2
• Emsco B-4 Cirrus
• Koolhoven FK.41
• Klemm L.26
• Klemm L.27
• Short Mussel
• Simmonds Spartan
• Spartan Arrow
• Westland Wessex
• Westland Widgeon

Engines on display

• A preserved ADC Cirrus II is on display at the Science Museum (London).

Specifications (Cirrus I)

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References

Notes

Bibliography

• The Aviation Ancestry Database of British Aviation Advertisements 1909–1990. Cirrus advertisements (retrieved 23 April 2020).
• Gunston, Bill. World Encyclopaedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989.
• Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. .
• Taylor, Douglas R. Boxkite to Jet: The Remarkable Career of Frank B. Halford. Rolls-Royce Heritage Trust. 1999. .

References

1. Taylor 1999, pp.74-5.
2. Taylor 1999, p.76
3. Gunston 1989
4. R. Cheyne Stout; "The Development of the Cirrus Engine", ''U.S. Air Services'', Volume 14, Number 4, April 1929. pp.53-4.
5. Aviation Ancestry (1929)
6. Lumsden 2003, pp. 130-132.
7. Jackson p.190 1973
8. Lumsden 2003, p. 130.