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Aviation History
1953
1953 - 0128.PDF
126 FLIGHT, 23 January 1953 COMMERCIAL-HELICOPTER ECONOMICS . . . Economic Position.—Present costs per seat-mile for present and projected types of helicopter, and fixed-wing aircraft, are shown in Fig. r. The total operating costs involved are from 170 per cent to 200 per cent of the "aircraft" costs shown, the lower percentages applying to the helicopters. It is obvious that at the present stage of development too few seats are being carried over too few miles. Increased payloads and speeds are again seen to be the first necessities for profitable future operation. In Sabena's scheduled mail operations, the total costs per mile for the Bell 47D machines during the first two years were 1 is 3d and 12s 4d respectively, but a reduction to 9s 6d was estimated for the third year with the introduction of a second circuit. A sobering thought is that these operating costs are comparable to that of a DC-4 carrying a payload of some seven tons, or over 40 times that of the Bell. Similarly high costs occurred in the first scheduled passenger service operated by B.E.A. with three-seat S-51S, in which the total costs were approximately £40 per flying hour, or 10s per mile. With fares at normal rates, and low load factors, the revenue obtained came to only a small percentage of these costs. A some what lower figure was achieved by Los Angeles Airways, also using S-51S, whose total operating costs per mile averaged 8s 6d during 1950. The indirect operating costs are undoubtedly swollen at present by the exceptionally high rate of insurance charged—some ihree times that for the fixed-wing aircraft. With increasing operating experience and recognized safety, however, this should fall to a more reasonable value. Up to the present time, comparatively little expense has been caused by the construction of rotorstations in Europe. Normal aerodromes and simply-equipped landing places have been regu larly used and, while experimental landings have been made on city-centre sites, no permanent city rotorstations have been con structed in Britain. Charter work on particular projects is at present the only economically practicable form of helicopter operation in this country. The ability of the helicopter to operate over difficult terrain was shown in last year's cable-laying operation over the Malvern hills, and its value in accurately and quickly spraying crops, especially in small fields and on hilly ground, is now well known. The Future Probable Equipment.—Opinion on the size and characteristics of future transport helicopters is divided. The airline operators, naturally, favour the large, fast machine which will provide them with the desired increased number of seats over increased distances Fig. 2. Probable future network of internal and short-stage European routes, as operated by the 160 m.p.h. "Bealine Bus." Figures represent journey /times in hours and/or minutes. Source : Ref. 11. in a given time, and with punctuality and regularity. An example is the B.E.A. 1951 specification for a 30-seat machine, to cruise at ! ' 138 m.p.h. over 115-mile stage lengths, and capable of develop ment to carry 35-45 passengers over 230-mile stages; while a revised requirement, according to Masefield, would now demand from 40-70 seats, and a cruising speed of 150 m.p.h. over a 230-mile operating distance for economic results. The hypo thetical "Bealine Bus" of i960 would meet this later requirement, cruising at 160 m.p.h. with 48-64 passengers at the much-reduced operating cost shown in Fig. 1. B.E.A.'s contention that such a machine should be the next step in British helicopter development after a period of trial operation with an 18-seat, 115 m.p.h. development of the Bristol 173, is by no means unanimously accepted by the helicopter manufacturers, many of whom believe that the projected machine is too large to be obtainable in one step. For many years such experts as Mr. Raoul Hafner have asserted that development should concentrate on a medium-sized machine, the first costs of which would be reduced by production of the type in large numbers. Although, on a weight basis, the helicopter is one and one-third times as expensive as the aeroplane for small numbers, it is especially suited to quantity production, and for large production orders the initial cost would equal, or be lower than, that of the aeroplane. To ensure the high demand for helicopters which alone would make large production orders possible, Mr. Hafner claims, medium-sized (say 20-seat) machines, intended for a wide market, should be designed; their operating costs would not be higher than those of the larger machines. The trend in the U.S.A. is for a markedly more gradual increase in the size of machines than that specified by Masefield. A recent survey of U.S. helicopter manufacturers' projects (described by our American correspondent on pages 101-102) has shown a probable three-phase development in which the original B.E.A. specification is approached only in the late 1960s, with no apparent sight of the "Bealine Bus" type within the period studied (up to 1970). The seat-mile costs in Table I on page 101 correspond approximately to 8^d, 6d and 4W respectively. While it is inevitable that differences of opinion concerning future helicopters should occur—and there are radically different viewpoints among the manufacturers themselves—it is nevertheless essential that the machines to be produced should directly reflect the operators' main requirements, and should be capable of economic operation; the question of initial cost is not so important as that of obtaining a commercially attractive vehicle which, in operation, will justify its heavy development costs. There already exists in the U.S.A. the Piasecki PD 22, capable of carrying 20 passengers, while the same company's XH-16 and the British Westland W.80 project come fairly near to the original B.E.A. specification, carrying 40-50 and 36 passengers respectively. The question of the cost of developing a new type of helicopter is of the greatest importance, and it is here that the Service departments could effectively show a new and constructive attitude. It should not be difficult to co-ordinate military and civil require ments for a transport helicopter for passenger and freight use, thus spreading the introductory costs of the new machine. The order of these costs is high; Masefield's calculations show a necessary capital outlay of about £21,000,000 spread over ten years, to bring 100 aircraft of "Bealine Bus" type into airline service. The cruising speed asked for in the "Bealine Bus," 160 m.p.h., is likely to remain on the optimistic side for a period longer than that envisaged, unless rotors are assisted in forward flight by the use of stub wings. It is not long since 150 m.p.h. was stated to be a maximum figure for development in the foreseeable future by one of Britain's most capable helicopter designers, although this referred to the "pure" helicopter without wings. It appears likely that this desired speed will be reached in less than ten years' time as part of a marked improvement in all-round performance, but that the main factor of cost reduction thereafter will be simplifica tion of design. Likely Routes.—Concerning the types of route over which the new generation of transport helicopters will operate, there is little difference of opinion. Several independent analyses of the general transport picture in this country, taking into account the speed and payload of the helicopter, have shown the rotary-wing type to be eminently suitable for stage lengths between 50 and 300 miles. The helicopter is faster than bus, train or present-day short-haul aeroplane for journeys from 250 miles down to 25 miles, but the time saved over the shorter distances would not be worth the fare increase over bus and train, except in certain isolated cases. Thus the helicopter could replace the aeroplane on all British domestic routes—with the exceptions of the long stages London- Edinburgh, London-Glasgow, and London-Belfast—and on the routes from London to Paris, Brussels and Amsterdam. Assuming the building of city-centre rotorstations in parallel with the development of the large passenger-carrying helicopter, marked improvements in speed and convenience are possible on these short-haul inter-city journeys (see Fig. 2). Main airports would be used to a small degree by helicopters in order to connect with
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