Westland CL.20
| Westland CL.20 | |
|---|---|
| Type: | Gyroplane , experimental aircraft |
| Design country: | |
| Manufacturer: | |
| First flight: |
February 5, 1935 |
| Number of pieces: |
1 |
The Westland CL.20 (including Westland Lepère CL.20 ) was a two-seat cabin gyrocopter , in 1934 in one copy in the UK at Westland Aircraft designed and built. Only the rotor system came from the Cierva Autogiro Company . In the literature, the designation C.31 is often assigned to the type within the Cierva designation sequence, although C.31 originally stood for the project of a high-speed gyroplane.
history
development
Westland gained initial experience in the field of gyroplane development with the five-seater C.29 , which, however, turned out to be unable to fly due to severe ground resonance problems . Even before the project was abandoned, the company turned to a smaller two-seater gyroplane designed by Frenchman Georges Lepère. After Weymann-Lepère was founded at the end of 1929, Lepère was involved in the construction of the C.18 gyroplane. The only built example (aircraft registration G-AAIH) of the two-seat cabin propeller was then sold to Great Britain. In 1932 Lepère switched to Lioré et Olivier (LeO), after which the French Cierva license passed from Weymann to LeO. Lepère constructed the C.27 here, which became known as the CL.10 (Cierva-Lepère). The CL.10, built during the summer of 1932, used much of the experience gained with the Cierva C.19 Mk. V and is seen as the first serious attempt at building a direct control gyroplane. Only two copies were built, of which the second prototype crashed on December 19, 1932 and claimed the first fatality in a gyroplane crash.
Despite this setback in gyroplane development, Westland decided to build its own two-seat cabin gyroplane. A Westland representative in Paris introduced Lepère to WE Petter , the son of Sir Ernest Petter, one of the company's two founders. Ernest Petter agreed to finance the construction of a second gyroplane after the C.29 .
testing
On September 24, 1934 the machine received its approval and the aircraft registration G-ACYI, but it was not until January 21, 1935 that the first taxi attempts followed in Yeovil . The CL.20 was then dismantled and taken to Hanworth Airfield on the road to Cierva . On February 5th, Cierva made the first flight, which lasted two minutes. Further testing quickly made it clear that the lift generated was too little. The machine with two crew members only reached a height of a few hundred feet. Then in July 1935 the engine was replaced by a new Pobjoy Niagara, with which the CL.20 flew for the first time on July 18, 1935. The buoyancy problem could not be solved with this measure. The last flight, after a total testing time of 8½ hours, took place on July 27, 1935, after which the machine was abandoned.
Petter managed to convince his father, as a sponsor, that the problems could be solved, and preparations could be made for the production of another six airframes . Production still started, but was stopped before the hulls were finished. The reason for this was probably the fact that Westland was busy with the series production of the Lysander and the construction work on the new Whirlwind fighter . The CL.20 was finally scrapped in 1938.
impact
Even 20 years after the CL.20, Lepére continued to develop this concept. In 1959, the two-seat cabin gyroplane Helicop-Air Girhel L50 was presented at the Paris Air Show, which was created with the help of Lepère. The technical data of this model are largely identical to those of the CL.20.
construction
The draft submitted by Lepère generally showed many similarities with the CL.10B, but had clear deviations in the details. While the stern of the CL.10 was based on that of the C.19 Mk. IV, the CL.20 had a triple vertical stabilizer that was mounted on a fixed horizontal stabilizer without moving rudders. Only the setting angle could be changed on the ground. One half of the horizontal stabilizer had a negative angle of attack to compensate for the torque of the propeller. It was controlled by a stick hanging from the rotor head, while the CL.10B used a steering wheel for this. The drive consisted of a 90 hp Pobjoy Niagara seven-cylinder radial engine . Cierva's three-bladed rotor system was installed on two aerodynamically shaped pipes above the cabin. Four tension wires stabilized the system. Before the start, the rotor could be set in rotation by means of a shaft extending from the rear of the motor, which could be switched on via a single-disc dry clutch from Ferodo.
The fuselage structure consisted of a fabric-covered, welded light metal construction with two longerons in the bottom area and a longitudinal beam at the top, resulting in a triangular cross-section. An elliptical fuselage cross-section could be achieved using stringers and form elements.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 side by side in a closed cabin |
| length | 6.18 m |
| Rotor area | 74.7 m 2 |
| Rotor speed | 210-235 |
| span | without wings |
| height | 3.13 m |
| Empty mass | 381 kg |
| Max. Takeoff mass | 636 kg |
| Top speed | 170 km / h |
| lowest horizontal speed | 40 km / h |
| Engine (after replacement) | 1 × seven cylinder Pobjoy Niagara S radial engine with an output of 95 hp, which drove a two-bladed propeller with a diameter of 2.21 m. |
See also
literature
- Richard Riding: Westland CL.20 - British pre-war lightplanes No. 4 . In: Airplane Monthly February 1989, pp. 118-120, 124
- Derek N. James: Westland Aircraft since 1915 , Putnam, 1991, reprint 2001, ISBN 0-85177-847-X , pp. 253-256
- Arthur WJG Ord-Hume: Autogiro - Rotary Wings Before the Helicopter , Mushroom Model Pub., 2009, ISBN 978-83-89450-83-8 , pp. 95, 291 f.
Web links
- Photo and brief historical overview on aviastar.org (accessed December 16, 2018)