Weymann-Lepère C.18

C.18
Role utility autogyro
National origin France
Manufacturer Weymann-Lepère
Designer Georges Lepère
First flight 12 August 1929
Number built 1

The Weymann-Lepère C.18 (also known as the Cierva C.18[1][a]) was an autogyro built in France in 1929.[3] It was entered in the Guggenheim Safe Aircraft Competition in the United States that year, but was not ready for competition and was not delivered for testing.[4] It was the first autogyro built with an enclosed cabin,[4] and one of the first rotary wing craft to be equipped with a rotor brake.[4]

Design

The C.18 was a tractor autogiro with stub wings that had upturned tips.[4] It had tailskid undercarriage and a conventional tail.[4] The enclosed cabin had seating for the pilot and one to three passengers.[5] Construction throughout was metal, using a stressed-skin method pioneered by designer Georges Lepère.[4] Power was originally from a Salmson 7AC[3][6] or Wright J-5[5] radial engine in the nose.

The main rotor had four blades and was wire-braced.[2] The horizontal stabiliser could pivot to deflect airflow from the propeller upwards into the rotor and therefore begin rotation.[5]

Development

The Cierva Company ordered the C.18 from their French licensee Weymann-Lepère for Loel Guinness so it could be entered in the Guggenheim Safe Aircraft Competition.[5] It was registered in the UK as G-AAIH in June, but first flew at Villacoublay on 12 August, probably with Juan de la Cierva himself at the controls.[2] It was shipped to the US in late August or early September, probably without its engine.[2]

Harold F. Pitcairn, Cierva's American licensee, hoped to enter his Pitcairn PCA-1 autogyro in the same competition.[2] However, when it was clearly not going to be ready in time, he arranged to enter the C.18 instead.[2] Pitcairn fitted it with a Wright J-6 engine, and modified it with a new rotor and hub of his design, a taller rotor pylon, improved landing gear, and other changes.[2] It first flew in this form in September, again probably with Cierva himself at the controls.[2] However, its poor performance and high levels of vibration meant that it would not be ready for the competition either, and was not presented for testing.[2][7]

It is not known to have flown after November 1929, and its ultimate fate is now uncertain.[2]

Specifications (final)

Data from Brooks 1988, p.96

General characteristics

  • Crew: 1 pilot
  • Capacity: 1–3 passengers
  • Powerplant: 1 × Wright J-6-7 air-cooled, seven-cylinder, radial engine, 168 kW (225 hp)
  • Main rotor diameter: 12.6 m (41 ft 4 in)

Notes

  1. ^ The designation C.18 strictly belongs to an unbuilt 1927 design by Juan de la Cierva for a small, single-seat autogyro to be powered by a Bristol Cherub or five-cylinder Siemens-Halske engine[2]

References

  1. ^ The Illustrated Encyclopedia of Aircraft 1982, p.1153
  2. ^ a b c d e f g h i j Brooks 1988, p.91
  3. ^ a b The Illustrated Encyclopedia of Aircraft 1982, p.1154
  4. ^ a b c d e f Brooks 1988, p.90
  5. ^ a b c d Brooks 1988, p.89
  6. ^ Jackson 1959, p.231
  7. ^ The Daniel Guggenheim International Safe Aircraft Competition: Final Report 1930, pp.6,14. Cierva and Pitcairn are both listed as entrants, but no aircraft from them appears in the table of flight test results.

Bibliography

  • Brooks, Peter W. (1988). Cierva Autogiros: The Development of Rotary-Wing Flight. Washington D.C.: Smithsonian Institute.
  • The Daniel Guggenheim International Safe Aircraft Competition: Final Report. New York: The Daniel Guggenheim Fund for the Promotion of Aeronautics. 31 January 1930.
  • The Illustrated Encyclopedia of Aircraft. London: Aerospace Publishing.
  • Jackson, Aubrey Joseph (1959). British Civil Aircraft 1919-59: Volume 1. London: Putnam.
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