| W.9 | |
|---|---|
 | |
| Role | Experimental helicopter |
| Manufacturer | Cierva Autogiro Company, Ltd. |
| First flight | 1945 |
| Retired | 1946 |
| Primary user | Air Ministry |
The Cierva W.9 was a British 1940s experimental helicopter with a three-blade tilting-hub controlled main rotor, and torque compensation achieved using a jet of air discharged from the rear port side of the fuselage. The design was not further developed into production, and the prototype crashed in 1946.
In 1943, primary investor G & J Weir Ltd. revived the moribund Cierva Autogiro Company to develop an experimental helicopter to Air Ministry Specification E.16/43. The W.9 was to investigate James G. Weir's contention that a powered tilting hub-controlled rotor with automatic collective pitch control, and torque reaction control using jet efflux, was both safer and more efficient than the Sikorsky R-4 helicopter fitted with manually controlled main rotor cyclic and collective pitch and the anti-torque tail rotor system. The W.9 was completed late in 1944 and assigned serial PX203. It was damaged during ground-running due to incorrect control phasing arising from a high order of pitch-flap coupling, and did not start test flying until 1945.
The most visible characteristic of the W.9 was torque compensation and directional control by using blown air rather than a tail rotor. A variable pitch fan cooled the engine; the heated air and engine exhaust passed through the long hollow tailboom and exhausted to port. [1] Foot pedals controlled the fan pitch. Of more importance, however, was the shaft-driven hydraulically-actuated rotor hub with rotational speed variation to give automatic collective pitch control. [2] Development of the rotor system resulted in a tilting hub combined with cyclic pitch control of each blade to minimize control forces. Manual control of collective pitch was added to the automatic collective pitch change system to provide precise vertical control in hover and the ability to cushion a landing from an autorotative descent.
The W.9 was first publicly demonstrated during an air display in Southampton on 22 June 1946. [3] It was displayed at the Seventh SBAC Airshow at Radlett in 1946 [4]
The helicopter was destroyed in an accident in 1946 and the project was abandoned. Parts of the W.9 rotor hub were used in the W.14 Skeeter prototype.
Cierva was bought out by Saunders-Roe, and that design entered production service in the 1950s as the Saunders-Roe Skeeter.
Data from Flight [5]
General characteristics
United Kingdom 
An autogyro, or gyroplane, is a class of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. While similar to a helicopter rotor in appearance, the autogyro's unpowered rotor disc must have air flowing upward across it to make it rotate.
Juan de la Cierva y Codorníu, 1st Count of la Cierva, was a Spanish civil engineer, pilot and a self-taught aeronautical engineer. His most famous accomplishment was the invention in 1920 of a rotorcraft called Autogiro, a single-rotor type of aircraft that came to be called autogyro in the English language. In 1923, after four years of experimentation, De la Cierva developed the articulated rotor, which resulted in the world's first successful flight of a stable rotary-wing aircraft, with his C.4 prototype.
A tiltrotor is an aircraft that generates lift and propulsion by way of one or more powered rotors mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a transverse rotor design, with a few exceptions that use other multirotor layouts.
The vortex ring state (VRS) is a dangerous aerodynamic condition that may arise in helicopter flight, when a vortex ring system engulfs the rotor, causing severe loss of lift. Often the term settling with power is used as a synonym, e.g., in Australia, the UK, and the USA, but not in Canada, which uses the latter term for a different phenomenon.
Helicopter flight controls are used to achieve and maintain controlled aerodynamic helicopter flight. Changes to the aircraft flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor blades that make the helicopter move in a desired way. To tilt forward and back (pitch) or sideways (roll) requires that the controls alter the angle of attack of the main rotor blades cyclically during rotation, creating differing amounts of lift at different points in the cycle. To increase or decrease overall lift requires that the controls alter the angle of attack for all blades collectively by equal amounts at the same time, resulting in ascent, descent, acceleration and deceleration.
The Cierva C.30 is an autogyro designed by Juan de la Cierva and built under licence from the Cierva Autogiro Company by A V Roe & Co Ltd (Avro), Lioré-et-Olivier and Focke-Wulf.
A coaxial-rotor aircraft is an aircraft whose rotors are mounted one above the other on concentric shafts, with the same axis of rotation, but turning in opposite directions (contra-rotating).
On a helicopter, the main rotor or rotor system is the combination of several rotary wings with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which connects through a combination of drive shaft(s) and gearboxes along the tail boom. The blade pitch is typically controlled by the pilot using the helicopter flight controls. Helicopters are one example of rotary-wing aircraft (rotorcraft). The name is derived from the Greek words helix, helik-, meaning spiral; and pteron meaning wing.
In aeronautics, a swashplate is a mechanical device that translates input via the helicopter flight controls into motion of the main rotor blades. Because the main rotor blades are spinning, the swashplate is used to transmit three of the pilot's commands from the non-rotating fuselage to the rotating rotor hub and mainblades.
The Saunders-Roe Skeeter is a two-seat training and scout helicopter that was developed and produced by British manufacturer Saunders-Roe ("Saro") of Cowes and Southampton, in the United Kingdom.
A rotorcraft or rotary-wing aircraft is a heavier-than-air aircraft with rotary wings or rotor blades, which generate lift by rotating around a vertical mast. Several rotor blades mounted on a single mast are referred to as a rotor. The International Civil Aviation Organization (ICAO) defines a rotorcraft as "supported in flight by the reactions of the air on one or more rotors".
The Fairey Jet Gyrodyne is a British experimental compound gyroplane built by the Fairey Aviation Company that incorporated helicopter, gyrodyne and autogyro characteristics. The Jet Gyrodyne was the subject of a Ministry of Supply (MoS) research contract to gather data for the follow-up design, the Rotodyne.
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of short take-off and landing (STOL) or short take-off and vertical landing (STOVL) aircraft cannot perform without a runway.
Autorotation is a state of flight in which the main rotor system of a helicopter or other rotary-wing aircraft turns by the action of air moving up through the rotor, as with an autogyro, rather than engine power driving the rotor. The term autorotation dates to a period of early helicopter development between 1915 and 1920, and refers to the rotors turning without the engine. It is analogous to the gliding flight of a fixed-wing aircraft. Some trees have seeds that have evolved wing-like structures that enable the seed to spin to the ground in autorotation, which helps the seeds to disseminate over a wider area.
The Cierva W.11 Air Horse was a helicopter developed by the Cierva Autogiro Company in the United Kingdom during the mid-1940s. The largest helicopter in the world at the time of its debut, the Air Horse was unusual for using three rotors mounted on outriggers, and driven by a single engine mounted inside the fuselage.
The Fairey FB-1 Gyrodyne is an experimental British rotorcraft that used single lifting rotor and a tractor propeller mounted on the tip of the starboard stub wing to provide both propulsion and anti-torque reaction.
The Cierva Autogiro Company was a British firm established in 1926 to develop the autogyro. The company was set up to further the designs of Juan de la Cierva, a Spanish engineer and pilot, with the financial backing of James George Weir, a Scottish industrialist and aviator.
The Cierva W.5 was a helicopter developed by the Cierva Autogiro Company in the United Kingdom. It was a single seater twin rotor helicopter- the rotors were mounted side-by-side on outriggers- with a wooden frame. It was powered by a 50 hp 4-cylinder air-cooled Weir engine. Its first flight was at Dalrymple, Ayrshire, on 7 June 1938, and it is considered to have been the world's second fully practical helicopter.
The SNCAC NC.2001 Abeille was a single engine, twin intermeshing rotor helicopter designed and built in France in the late 1940s. Three were completed but only one flew, development ending when SNCAC was closed.
The Nord 1700 Norélic or SNCAN N.1700 Norélic was a French helicopter with several novel control features. Only one prototype was built, though it was intended to lead to series production.
The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.