The Rotodyne, made by the Fairey Aviation Company, was shown off before the Press today at the White Waltham aerodrome, near Maidenhead in Berkshire.
The Rotodyne, made by the Fairey Aviation Company, was shown off before the Press today at the White Waltham aerodrome, near Maidenhead in Berkshire. It is a true vertical take-of airliner. It ascends vertically in the same manner as a helicopter and, having gained height, flies forward as a fixed-wing airliner. By so doing ti overcomes the speed limitations of the helicopter and dispenses with the long runways for fixed-wing planes.
In aviation circles the Fairey Rotodyne is regarded as one of the most interesting and potentially valuable aircraft in the air at the present time. Today was not the first time that the Rotodyne had been flown publicly. Hitherto, however, it had been seen in vertical take-off only. Today it took off vertically and at a appropriate height proceeded horizontally on course.
Although there are today several thousand helicopters flying in all parts of the word, very few of these machines are being used for genuine transport purposes. Those which are - chiefly in the U.S.A. and in Belgium - are heavily subsidized and in any case are operated on a relatively small scale and are not regarded as profit-making vehicles. For this there are many reasons: the helicopter, fundamentally is still in its infancy and the small machines which are commercially available cannot carry sufficient payload to bring in a worthwhile return; their range is only sufficient to enable them to operate locally; under all conditions of flight their propulsive efficiency is poor; but, most important of all, inherent aerodynamic limitations imposed by the rotor preclude the possibility of satisfactory helicopter cruising at speeds greater than about 110-115 miles per hour. Admittedly the helicopter's ability to land close to city centres is no small convenience, but it is at a cost which, in the past, has been regarded as much too high to make them attractive for regular transport functions.
The Rotodyne is not only the first aircraft which really promises to overcome all three deficiencies; it also enjoys certain additional advantages previously denied to all rotary-wing flying machines. In appearance the Rotodyne is a combination of helicopter and airliner; and, in fact, it is both. It is much larger than any previous British rotary-wing machine, having a fuselage big enough for 48 passengers or five tons of freight. It has two turbine engines, giving adequate power for flight in complete safety with one engine stopped. It has a fixed wing and propellers in addition to its 90 foot diameter rotor.
Each engine is a Napier Eland propeller turbine with a combined horse power of about 7,000. Before starting these engines, the Rotodyne pilot places the propellers in fine pitch, so that very little thrust is generated and minimum power absorbed. The propellers are mounted in the conventional way on the front of each engine, but at the rear of the engine is an auxiliary air compressor which takes in fresh air from above the wing. As the Elands run up to speed these compressors are brought into action by means of a type of fluid-drive clutch. The air from the compressors is ducted through large pipes along the inner part of the wing and up to the hub of the rotor. Here the air is fed past rotary seals and then into the blades themselves, through a trio of pipes leading to pressure-jet units at the tips. These unite operate like the combustion chamber of a jet engine. The compressed air is mixed with kerosene (also fed through a pipe inside each blade) and the resulting combustion at the tip of each blade produces a forward thrust which drives the rotor round. This very direct method of driving a rotor has many advantage. In particular it eliminates the mechanical shafts and gears which would otherwise be needed - and which, to transmit several thousand horsepower, would be tremendously heavy.
When the rotor is running a full speed the Rotodyne takes off vertically and climbs away as a helicopter, steering in the required direction by differentially altering the pitch of the propellers. As height is gained both propellers are gradually brought into forward positive pitch to accelerate the forward speed. At an appropriate height and speed and clutches are disengaged so that the air supply to the rotor dies away and the tip jets are extinguished. Thus all the necessary engine power is transmitted to the propellers and the Rotodyne flies as a fixed-wing airliner, the rotor being left to "windmill" of its own accord.
As speed builds up the stub wing increasingly takes on the job of supporting the aircraft until, at a cruising speed of some 185 miles per hour about 60 per cent of the lift is provided by the wing. The resulting "unloading" of the rotor removes the most critical of the aerodynamic restrictions and makes possible a speed about twice that of present helicopters. Moreover, the fact that the forward propulsion is accomplished by propellers and not by a rotor greatly increases the efficiency of the aircraft.
For landing the pilot merely goes through the same cycle of operations in reverse, finally letting down vertically with the rotor once more absorbing all the power.
From the passenger's viewpoint there is little to distinguish the Rotodyne from a present-day airliner. It is sufficiently large and advanced in design to offer a completely comfortable ride, turbine power helping to reduce in-flight noise and vibration to a marked extent.
Airliner operators, as well as all kinds of other civil and military organizations are watching the flight progress of the Rotodyne with the extreme interest. In it they see the promise of an economical vehicle which can carry loads between the centres of cities, or along chains of islands, or across arduous and undeveloped territory, more rapidly than anything else yet developed by man. On the London-Paris route, for example, it is theoretically possible for a Rotodyne to take off with a full load from a suitable site in the hear to London and alight in the centre of Pairs barely an hour later (at about the time that fixed-wing passengers would be arriving at London Airport to board their plane). In additional such services could be provided in any weather conditions acceptable to fixed-wing aircraft since the Rotodyne can be equipped with every flying aid for navigation and blind-landing purposes. The maximum range of, the machine is 450 miles at a cruising speed of 185 m.p.h.