Cierva C.8

The first example, the C.8R (known to Avro as the Type 587) was a rebuild of the C.6D, fitted with stub wings and paddle-shaped main rotor blades. This was followed by the new-built C.8V (or Type 586) that was eventually converted back into an Avro 552 after testing. The next model was the definitive C.8L prototype (or Type 575). The Mark II was based on the Lynx-engined Avro 504N two-seat trainer.Flight 5 July 1928, p. 543

By now, Cierva's efforts were attracting the attention of buyers. The first customer was the British Air Ministry, which placed an order for a machine in 1927. This was completed as the Type 611, test flown by Bert Hinkler at Hamble and then delivered to the Royal Aircraft Establishment by Cierva himself in Britain's first cross-country rotorcraft flight on 30 September that year. The next example was purchased by Air Commodore James G. Weir, chairman of Cierva, and flown in the 1928 King's Cup Air Race before being used to make demonstration flights around continental Europe.

The two final C.8s were sold in 1928, one to the Italian government, and one to American Harold Pitcairn, who would go on to purchase manufacturing rights for the United States. The C.8W bought by Pitcairn would make the first autogyro flight in the United States at Willow Grove, Pennsylvania, on 18 December 1928. The C.8W is the oldest autogyro in the United States.Charnov, Dr. Bruce H. "[http://vtol.org/02D0C1B0-8821-11E2-8DA50050568D004 A Critical Re-Examination of the Franklin Institute Rotating Wing Aircraft Meeting of October 28 – 29, 1938] {{Webarchive|url=https://web.archive.org/web/20160513164350/http://vtol.org/02D0C1B0-8821-11E2-8DA50050568D004 |date=13 May 2016 }}" page 3-4. 62nd Annual Forum, American Helicopter Society, May 2006. Accessed: 30 December 2013.

As of 2007, two examples are extant: Weir's machine preserved at the Musée de l'Air et de l'Espace in Paris, and Pitcairn's at the National Air and Space Museum in Washington, DC.

;C.8R: C.6D fitted with new wings and rotor blades, powered by a 97-kW (130-hp) Clerget engine. (1 converted)

;C.8V: Two-seat model, powered by a 134-kW (180-hp) Wolseley Viper piston engine.File:Hall Helicoptere Musee du Bourget P1020335.JPG]]

;C.8L: (4 built)

;C.8L Mk II: Fitted with short-span wings, powered by an Armstrong Siddeley Lynx IV radial piston engine. The aircraft took part in 1928 King's Cup Air Race. Built in the United Kingdom as the Avro Type 617. (1 built)

;Weymann-Lepère C.18: Version of C.8L Mk II built under license in France.{{Cite web|url=https://sites.google.com/site/stingrayslistofrotorcraft/weymann-lepre-c18|title = Weymann-Lepère C.18 - Stingray's List of Rotorcraft}}

;C.8L Mk III: Two aircraft built for the Italian government in 1928.

;C.8W: Powered by a 168-kW (225-hp) Wright Whirlwind radial piston engine. This version was built for Harold Frederick Pitcairn. Original designation C.8L Mk IV. (1 built)

{{Aircraft specs

|ref=Jane's all the World's Aircraft 1928,{{cite book |title=Jane's all the World's Aircraft 1928 |editor1-last=Grey |editor1-first=C.G. |year=1928 |publisher=Sampson Low, Marston & company, ltd |location=London |page=262c}} Flight 5 July 1928 p. 543

|prime units?=imp

|crew=1

|capacity=1 plus {{cvt|50|lb}}

|length ft=36

|length note=

|span ft=23

|span in=2

|span note=

|height ft=14

|height in=9

|height note=

|wing area sqm=

|wing area sqft=

|wing area note=

|aspect ratio=

|airfoil=

|empty weight lb=1735

|gross weight lb=2380

|max takeoff weight kg=

|max takeoff weight lb=

|max takeoff weight note=

|fuel capacity={{cvt|24|impgal|USgal l}}

|more general=

|eng1 number=1

|eng1 name=Armstrong Siddeley Lynx IV

|eng1 type=7-cylinder air-cooled radial piston engine

|eng1 hp=200

|prop blade number=2

|prop name=wooden fixed pitch propeller

|prop dia m=

|prop dia ft=

|prop dia in=

|prop dia note=

|rot number=1

|rot dia ft=39

|rot dia in=8

|rot area sqft=1236

|rot area note=

|max speed mph=100

|cruise speed mph=85

|stall speed kmh=

|stall speed mph=

|stall speed kts=

|stall speed note=

|never exceed speed kmh=

|never exceed speed mph=

|never exceed speed kts=

|never exceed speed note=

|minimum control speed mph=25

|range km=

|range miles=

|range nmi=

|range note=

|ferry range km=

|ferry range miles=

|ferry range nmi=

|ferry range note=

|endurance=3 hours at cruising speed

|ceiling m=

|ceiling ft=

|ceiling note=

|g limits=

|roll rate=

|climb rate ftmin=500

|time to altitude=

|wing loading kg/m2=

|wing loading lb/sqft=

|wing loading note=

|disk loading kg/m2=

|disk loading lb/sqft=

|disk loading note=

|fuel consumption kg/km=

|fuel consumption lb/mi=

|power/mass=11.9 lb/hp (7.24 kg/kW)

|thrust/weight=

|more performance=

}}

;Notes

{{Reflist}}

;Bibliography

• {{cite magazine |title=British Aircraft & Aero Engines: The Cierva "Autogiro" C.8. Mark II. |magazine=Flight |date= 5 July 1928 |volume=XX |issue=27 |page=543 |url=https://archive.org/details/Flight_International_Magazine_1928-07-05-pdf/page/n21/mode/2up |access-date=10 November 2021}}
• {{cite book |last= Taylor |first= Michael J. H. |title=Jane's Encyclopedia of Aviation |year=1989 |publisher=Studio Editions |location=London |pages=254 }}
• {{cite book |title=World Aircraft Information Files |publisher=Bright Star Publishing|location=London |pages=File 891 Sheet 28–29 }}
• [https://web.archive.org/web/20040203141524/http://www.nasm.si.edu/research/aero/aircraft/cierva_c8w.htm NASM website]
• [https://web.archive.org/web/20070210191445/http://www.britishaircraft.co.uk/aircraftpage.php?ID=833 Cierva C.8] – British Aircraft Directory

{{commons category inline|Cierva C.8}}

{{Avro aircraft}}

{{Cierva aircraft}}

Category:1920s British experimental aircraft

Category:Single-engined tractor autogyros

Category:Aircraft first flown in 1926

C.8