Fairey Rotodyne

Fairey Rotodyne
The venerable Fairey Rotodyne on a test flight. (image source unknown)
Description
Role	Medium range city-to-city commercial transport
Crew	2 pilots and between 57 and 75 passengers
Dimensions
Length	58 ft 8 in	17.88 m
Rotor span	90 ft	27.43m
Height	22 ft 2 in	6.76 m
Disc area	591m²
Weights
Empty
Loaded	33,000 lb	14,968 kg
Maximum take-off	38,000 lb	17,237 kg
Powerplant
Engines	2 Napier Eland turboprop
Power (each)	2,800 hp	2,088 kW
Performance
Maximum speed	185 mph	298 km/h
Range	450 mi	724 km
Service ceiling
Rate of climb

The Fairey Rotodyne was an unconventional aircraft design. A cross between an autogyro and a helicopter and fixed wing aircraft, the Rotodyne had a large, four-bladed rotor, similar to a helicopter's, and two Napier Eland N.E.L.3 turboprops mounted under short wings. The rotor was spun by connecting the main engines to two compressors, by way of a clutch, and the compressed air produced was mixed with fuel and burned from jets on the tips of the blades, and hence no tail rotor was required to counter torque.

The market for the Rotodyne was that of a medium-haul 'flying bus': it would take off vertically from an inner-city heliport, with all lift coming from the rotor, and then would increase speed, eventually with all power from the engines being transferred to the propellors and the rotor autorotating, much as an autogyro's does. In this mode, the collective pitch, and hence drag, of the rotors could be reduced, as the wings would be taking as much as half of the craft's weight. The Rotodyne would then cruise at speeds of about one hundred and fifty knots to another city (say, London to Paris) where it would convert back to a tip jet helicopter, again landing vertically in the city centre - the same role proposed for tilt rotors in more modern times.

Only one Rotodyne prototype was built, but it performed as desired. It set a world speed record for a helicopter, at 190.9 mph (307 km/h) on 5 January 1959, over a 100 km closed circuit. As well as being fast, the craft had several safety features: it could hover with one engine shut down and its propellor feathered, and the prototype demonstrated several fully autogyro landings. The prototype was demonstrated several times at the Farnbourgh and Paris air shows, regularly amazing onlookers. The Rotodyne's tip drive and unloaded rotor made her performance far better when compared to pure helicopters and other forms of 'convertiplanes'. The aircraft could be flown at 175 knots (324 km/h) and pulled into a steep climbing turn without demonstrating any adverse handling characteristics.

The one great criticism of the Rotodyne was the noise the tip jets made, however, the jets were only run at full power for a matter of minutes during departure and landing and indeed, the test pilot Ron Gelattly made two flights over central London, and several landings and departures at Battersea Heliport with no complaints being registered. There was also a noise-reduction program in process and had managed to get the noise level down to the desired level of 96 dB from 600 feet (180 m) away, less than the noise made by a London Underground train, and at the time of cancellation, silencers were in the pipeline which would have reduced the noise even farther.

Throughout the world, interest was growing in the prospect of direct city-to-city transport. British European Airways announced that it was interested in the purchase of six craft, with a possibility of up to twenty. The Royal Air Force ordered twelve military transport versions, and New York Airways looked into the purchase of five. Most significantly, there were rumours that the US Army was interested in buying two hundred.

None of these purchases occurred. In 1959 the British Government, seeking to cut costs, decreed that the number of aircraft firms be lowered. Fairey, then the helicopter division of Bristol, was to be taken over by Westland, and the axe fell as BEA and the RAF both withdrew their orders.

It is only relatively recently that interest has been re-established in direct city-to-city transport, with aircraft such as the Bell/Augusta BA609 and the Carter Copter.

Categories: British airliners 1950-1959 | Rotorcraft