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Aviation History
1951
1951 - 0123.PDF
FLIGHT, 18 January 1951 79 THIS is the third and last of a special series of articles by the former Deputy Director of Helicopter Research and Develop- ment, Ministry of Supply. In the first two he reviewed the history of the helicopter and discussed various aspects of detail design; in the present contribution he explains the value of this type of aircraft in the light of its unique characteristics, and indicates the most likely line of future development; he also reviews some outstanding current designs, particularly those emanating from France. Largest ever : The Howard Hughes XH-17 has a jeudriven rotor 130ft in diameter. Two 3,000 h.p. gas turbines provide compressed air for the combustion units at the rotor tips. A French intermeshing-rotor design . the S.N.C.A.C. N.C.200I. Experimental single-seat S.E.3I0I. built as a scale model of a projected ten-seoter and also developed as a two-seater. and early 1950, a night mail service was flown to schedule between Norwich and Peterborough. A similar mail service is in operation in the Los Angeles area of California, and has been very successful. Thirdly, even though it has been available for only a few years in practical form, the helicopter has a noteworthy series of rescues to its credit. It has been used to take crews from sinking ships, to pick up fishermen marooned on ice-floes, to evacuate casualties in Burmese and Malayan jungles, and to rescue injured cre\* and passengers from an airliner which crashed in impenetrable forested area in New- foundland; while in this country the revictualling of the storm-bound Wolf Rock Lighthouse will be remembered. The American Air Force authorities, fully alive to the value of the helicopter for rescue purposes, last year held a com- petition for a type intended mainly for Arctic rescue opera- tions. Fourthly, there are a host of other practical tasks for the helicopter, such as aerial survey; prospecting; forest, pipe- line, power-line and coastguard patrol; crop-dusting and pest-control generally; and medical and veterinary work in sparsely populated districts. Every one of these opera- tions has already been carried out with complete success by rotating-wing aircraft, and in all cases more efficiently than by any other known method. Enough has been said to show that the helicopter, even in its present relatively undeveloped form, is already proving its value in many directions. All these more or less experi- mental operations have helped in developing techniques, and have brought to light the shortcomings of the avail- able equipment. The ideal at which the airline operator must aim is main- tenance of schedules, even under completely blind condi- tions from take-off to landing. Already the existing heli- copter can be flown blind for limited periods by compe- tent pilots using standard instruments. It is, however, a fatiguing process, and before full-scale commercial opera- tion in all weathers is practicable it will be necessary to im- prove stability and handling characteristics. Navigational and ground-lighting aids have already been developed to a stage which is satisfactory so long as dear conditions prevail up to some 500ft from the ground; but to make any further appreciable improvement in safety and reliability of operation a blind-approach aid is necessary. Work in this direction has been proceeding for some time. As regards the future helicopter itself, the following are the directions in which improvements must be sought: — (1) Mention has already been made of the pilot-fatigue associated with blind flying. Operation into city centres will generally involve the use of small sites closely sur- rounded by buildings, and the minimum size for such a site will clearly be dependent on the steepness with which approaches can be made. Steep approaches are associated with very low forward speed, so that it is essential that future helicopters should have good control and stability characteristics under these conditions. (2) The scope of all existing helicopter operations is limited by the fact that the types in use are all single- engined. Since aircraft transport can most advantageously compete with surface transport where water crossings are involved, and since the greatest advantage which the heli- offers in civil transport is its ability to operate from the centres of cities, the multi-engined helicopter is essen- tial before wide-scale scheduled operations can become feasible. (3) Existing helicopters are expensive to operate and, in- deed, their commercial use to-day is possible only where some form of subsidy is given, or, alternatively, where the service rendered is such that no other vehicle can perform it and high rates can accordingly be charged. The over- riding consideration in the next generation of helicopters is, therefore, low operating cost. To achieve this aim the initial price must also be brought down The present high selling price is, of course, largely due to the fact that heavy develop- ment costs are spread over relatively few aircraft. This will automatically correct itself when the right type of heli- copter is available and the number which can be sold in- creases. Cruising speeds must be raised, since high operat- ing speed is advantageous in reducing journey tirrx**.,
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