Helicopters

Early British experience with rotorcarft was largely confined to autogiros which had served a useful purpose with 529 Sqn on calibration duties during the war. However, the first practical helicopter, the Sikorsky R-4, had been imported from the United States and there was renewed interest in the type. Specifications had been issued during the war and a number of interesting types were produced as a result.

Cierva W.9

G&J Weir Ltd had been involved in helicopter design at the outbreak of the war with the W.5 and W.6 and as a result of pressure had succeeded in securing specification E.16/43 which was issued to the Cierva company in which Weir's had a stake. The W.9 was the result, the first of two intended machines, PX203, flying in late 1944 or early 1945 from Henley-on-Thames. The design was basic and in its life it went through numerous changes. In principle it comprised a glazed cockpit area, a conical tubular fuselage and an upright fin. The Gipsy Six engine drove a three-bladed rotor with exhaust bled through a vent in the tail in lieu of a tail rotor, a remarkable advance at the time. The second machine was not built and the sole W.9 was damaged beyond repair in January 1948.

Fairey Gyrodyne, Jet Gyrodyne and Rotodyne

The FB.1 Gyrodyne was a pre-war design resurrected in 1946 when specification E.4/46 was issued. It comprised a tubby fuselage with stub wings, a single rotor and a taiplane with twin fins and rudders. Power was provided by a 515hp Leonides engine driving the main three-blade rotor and a propellor on the starboard wing to counter yaw. Possible army needs were covered by specification A.7/47 and serials VW796-7 were allocated. A further specification, E.16/47 was issued with an order for one aircraft, VX591. In the event the first Gyrodyne was registered G-AIKF and as such it flew on 7 December 1947. On 28 June 1948 it established a speed record for helicopters of 123.4mph but on 17 April 1949 it crashed, killing the crew, while preparing for a further record attempt. A second Gyrodyne, G-AJJP, was also built but was grounded in 1949. From about 1947 there had been interest in a large transport helicopter from several quarters and Fairey secured specification RH.124D which included provision for a test 'model'. Serial XD759 was allocated but it had to be changed to XJ389 through having been duplicated. The test vehicle was the second Gyrodyne rebuilt with a large twin-bladed propellor with pressure-jets at the blade tips as the Jet Gyrodyne. These were driven from the Leonides engine which also powered pusher propellors on each stub wing tip. In take-off and landing maximum power was applied to the main rotors but as the machine lifted power was transferred to the propellors for maximum forward speed and the rotor left to auto-rotate. The first free flight was made in January 1954 with transitional flight in March 1955. Flight testing was largely complete by 1957 when the Rotodyne flew and the aircraft survived to be preserved at Cosford.

Gyrodynes, with engine(s) for forward propulsion and rotor tip power for vertical take-off, were of continuing interest after the war with the Gyrodyne and Jetcopter. Jet-driven rotors, as described above, offered considerable wieght and complexity reduction and Faireys were interested in development. Over a number of years the Company refined ideas for a passenger-carrying aircraft capable of operating commercially. Eventually the design firmed up as the 40+ passenger Rotodyne to meet the BEA requirement for a 'bus' to transfer passengers between citycentres. Specification RH.142D was issued with serial XE521 and a second machine, XH249, was envisaged to meet an army need described in OR.334. In the event the latter, the Rotodyne Z, was not built. The Rotodyne was completed in 1957 and, powered by two Napier Eland engines, it first flew untethered on 6 November of that year. A large 58ft 8in fuselage was surmounted by the rotor head caryying a four-bladed rotor. Shoulder wings of 46ft 4in span set about half-way along the fuselage carried the two engines driving conventional propellors and a large tailplane, also set atop the rear fuselage, was fitted with twin fins and rudders. Transitional flights were conducted between April and October of 1958 and development proceeded with remarkably little in the way of problems for such a complex project. Consolidation in the aircraft industry combined with defence cuts and noise problems led to the Rotodyne being scrapped in May 1962.

Bevan Brothers E.1/48 Jetcopter

As early as 1928 the Air Ministry had ordered a form of autogyro, the Helicogyre, from the Italian designer Isacco. While similar in principle to an autogiro, the type featured small engines attached to the rotor blades. It was not successful and Isacco worked on other projects until after the war when he came to England from France to work with Bevan Brothers on specification E.1/48. This provided for a jet-powered version of the Helicogyre, the Jetcopter. Three captured Focke-Achgelis Fa330 rotor-kites were brought to the UK with the serials VX259, 266 and 850 to provide the basis of the new helicopter. In the event the project was abandoned in 1951. (The Fa330 was extensively tested until about 1950, primarily at the AFEE.)

Cierva W.11 Air Horse

The W.11 was intended to meet a range of needs including crop-spraying and transport and in 1946 specification E.19/46 was issued to cover the procurement of a prototype; later a second machine was ordered. It was a large machine with three rotors, one at the front and one on each side, all powered by a single Merlin engine. The fuselage was of box section and was nearly 90ft long, with overall width of 95 ft. Twin fins and rudders were set on the end of short tailplanes and the helicopter featured a simple long-stroke undercarriage. With its rotors set on outriggers, the design may well have been influenced by the Focke-Achgelis Fa223E which had been evaluated at AFEE late in 1945 as VM479. First untethered flight of VZ-724/G-ALCV was on 8 December 1948 at an all-up weight of 14,600lbs and progress was steady, with the second aircraft, WA555/G-ACLW ready for trials by October 1948. VZ-724 was lost on 13 June 1950 with the loss of the crew of three and when Saunders-Roe took over Cierva in 1951 the project was abandoned.

Bristol 173

The Type 173 was essentially a civil project for a ten-seat helicopter for which in due course specification E.4/47 was issued. The Bristol proposal was for a tandem rotor machine with high commonality with the smaller Type 171 (later Sycamore). A long, slender, fuselage was fitted with a fixed four-wheel undercarriage and sharply upswept tailplane. The first Type 173 flew on 3 January 1952 as G-ALBN and later, in 1953, it was allocated the serial XF785 for deck landing trials. The second prototype was G-AMJI /Xh279 with revised tailpane which was also engaged on service trials. Serial XG354 was allocated to an airframe used as a ground test-rig. Three series 3 aircraft were ordered with the Leonides Major driving four-bladed rotors and with a taller rear pylon. They were XE286-8 (G-AMYF-H) but only the first had begun ground running in November 1956 when work on the type was stopped. The RAF remained interested in the design and this led to the Type 192 Belvedere.

Percival P.74

Rotor-tip drive through jet exhaust was seen as being a solution to problems of torque and the weight of engine and transmission involved in driving a conventional helicopter with tail rotor. Hunting teamed with neighbours Napier to build the P.74 to specification EH.125D to be powered by two 750hp Oryx engines. The shape approximated that of a barrage balloon with windows and a three-bladed rotor and the serial XK889 was allocated. After many delays through the need to make adjustments to the design - including fitting a tail rotor - the aircraft was rolled out in May 1956. Attempts to lift it from the ground were fruitless and although the manufacturers redsigned the aircraft the project was abandoned in 1957.