Cierva C.8

The Cierva C.8 was an experimental autogiro built by Juan de la Cierva in England in 1926 in association with Avro. Like Cierva's earlier autogiros, the C.8s were based on existing fixed-wing aircraft fuselages - in this case, the Avro 552.

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 2-seat trainer.^[1]

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 autogiro flight in the United States at Willow Grove, Pennsylvania on December 18, 1928. The C.8W is the oldest autogiro in the USA.^[2]

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.

Variants

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.

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)

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)

Specifications (C.8 Mark II)

Data from Flight^[3]

General characteristics

• Crew: 1
• Capacity: 1 passenger and 50 lb
• Length: 36 ft (11 m)
• Rotor diameter: 23 ft 2 in (7 m)
• Height: 14 ft 9 in (4.5 m)
• Empty weight: 1,735 lb (790 kg)
• Loaded weight: 2,380 lb (1075 kg)
• Powerplant: 1 × Armstrong-Siddeley Lynx IV radial piston, 180 hp ()210 bhp
• Propellers: four-bladed doubly articulated rotor
  • Propeller diameter: 39 ft 8 in (12.1 m)
• Fuel capacity: 24 gallons (108 litres).

Performance

• Maximum speed: 100 mph (153 km/h) at sea level
• Cruise speed: 85 mph (129 km/h)
• Stall speed: 25 mph (40 km/h)
• Endurance: 3 hours at cruising speed
• Rate of climb: 500 ft/min (2.54 m/s) at sea level

References

Wikimedia Commons has media related to Cierva C.8.

Notes

Bibliography

• Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. p. 254. 
• World Aircraft Information Files. London: Bright Star Publishing. pp. File 891 Sheet 28–29. 
• NASM website
• britishaircraft.co.uk
• THE CIERVA "AUTOGIRO" "C.8. MARK II.' Flight 1928

See also