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Aviation History
1953
1953 - 0127.PDF
FLIGHT, 23 January 1953 125 Apparently ensnared was this S-51, spraying hops at Goudhurst, Kent, in July, 1950. Hitlers have since replaced these machines for spraying and dusting. HELICOPTER VERSUS PEST . . . ing, two containers are attached, one on each side of the engine, holding a total of some 40 gallons of chemical. Large hoppers are substituted for crop-dusting work. At present the Franklin engines have to be returned to the U.S.A. for periodic com plete overhaul after 600 hr, but future engine overhauls at the company's main base at Bourn, Cambridge (where com prehensive general maintenance facilities are already provided) are planned. The ability of the firm to integrate spray ing by helicopter, aeroplane and ground tractor is a useful feature in all cases of bad weather operation. Commercial-Helicopter Economics A Review of Existing Knowledge and Future Prospects ALTHOUGH at present overshadowed by its many military applications, the question of the rotorplane's use for regular civil transport duties is of outstanding importance. We present here a survey of the major economic aspects of this problem, prepared by a member of "Flight's" editorial staff. References quoted in the article are listed on page 128. WITH the general acceptance of a new form of transport able to move vertically up and down, has come a similar oscillation in hopes for its operating economy. In the helicopter's infancy, over-optimistic fore casts of an early low-cost ubiquity alternated with periods of total disinterestedness, except for those who saw in the rotorplane more than just an aeronautical novelty, and whose efforts have been responsible for this country's continued helicopter development. In recent years, however, several serious economic studies have been made by notable experts in the fields of helicopter design and operation, and it is possible to discern the pattern of economic progress which is being formed. An attempt is here made to review the main trends in this most important aspect of helicopter use, and to give the more significant estimates of costs which have been made. It would be dangerous to use these figures without a full knowledge of the assumptions made, however, and a list of sources for further reference is given at die end of this text. A logical approach to this study of rotor- plane economics is the consideration of past and present conditions, and future prospects, in turn, and this method has here been adopted. Past Development During the past ten years, it has been almost entirely in the field of non-scheduled transport that the helicopter's operational development has progressed. In this field, for many specialized uses, the helicopter has proved preferable to other vehicles. Examples are rescue, surveying, ambulance and agricultural work, and, of course, the varied military uses which have provided strong impetus for helicopter development as a whole. Of the factors which have made the helicopter suitable for these particular jobs, possibly the most important is its peculiar ability to operate into and from confined spaces, and over difficult terrain or stretches of water. Its convenience and the directness of journeys by helicopter have also given an overall speed advantage over most forms of surface transport, and over the aeroplane for short-distance flights; and thus for these special jobs the use of the helicopter has been justified. Economic justification has not yet been consistently found for scheduled passenger services by rotorplane. Mail delivery was the first type of scheduled work to be taken up, and regular operations in the U.S.A. were begun by Los Angeles Airways in October, 1947. In 1948, B.E.A. inaugurated the first British regular mail service (see page 123), and was followed the same year by the Ostermans Aero Company of Stockholm, Sweden; and in 1949 by Helicopter Air Services of Chicago, U.S.A., and the Belgian airline Sabena. In the winter months of 1949-50, B.E.A. made an important series of experimental night-mail flights; and in 1950 the Corporation flew the world's first scheduled passenger service, when useful operating experience, even if not accompanied by financial success, was obtained. Present Situation Helicopters in Use.—In this country and in Europe in general the machines at present in general civil use are the Sikorsky S-51, Bell 47D, Hiller 360 and, increasingly, the Bristol 171. Some of these small single-rotor machines are gradually being replaced by larger types, such as the S-55, carrying ten passengers, or correspondingly increased freight payload, but experience in twin-rotor helicopters is at present lacking. The larger British and American single and twin-rotor machines now existing will gradually come into com mercial use, and it appears that the next immediate step in commercial helicopter development will be the gaining of experience in the operation of types such as the Bristol 173, the Sikorsky S-55, and the Piasecki PD-22. The present class of machines simply does not carry sufficient payload for unsubsidized operation at break-even cost, and the increase in payload capacity ranks jointly with an increase in speed as the primary item of the necessary improved performance for regular passenger and freight use. Routes.—The routes operated by B.E.A. in this country up to the present time are described elsewhere in this issue by Dr. Hislop. The type of short-haul passenger routes which will become economic for helicopter operation and which will even tually cover the British Isles in a complete net work, have been indi cated by the initial Liverpool-Cardiff and Birmingham - London services. For mail ser vices, a round circuit, or combination of cir cuits, stopping at a number of points, has been favoured as the most economic tech nique, not only by B.E.A., but by com panies in Belgium, Sweden and the U.S.A. Fig. 1. Aircraft costs per seat-mile (at 2,000 hr utilization) plotted against stage distance, for helicopters (existing and projected) and fixed- wing aircraft. Source: Ref. 11. o 100 200' 300 STAGE DISTANCE (statute milei)
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