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Aviation History
1948
1948 - 1996.PDF
636 FLIGHT NOVEMBER 25TH, 1948 Discussing the Helicopter All-day Joint Meeting of the Royal Aeronautical Society and the Helicopter Association of Great Britainr AST Saturday was a strenuous but interesting and fruit- ful one for aircraft technicians. The Royal Aero- —' nautical Society and the Helicopter Association of Great Britain held an all-day meeting at the Institution of Civil Engineers." Altogether five papers were read, two during the morning and three in the afternoon, and there were discussions after the papers as well as a longer one in the evening. The two morning papers dealt with the general prob- lems of the helicopter for civil use. W/C. R.A.C.Brie, A.F.JR.Ae.S., stated the operational point of view, while Capt. R. N. Liptrot, C.B.E., B.A., outlined the technical problems of the civil helicopter. The afternoon papers were designed to state the con- structors' approach to the problem. J. A. J. Bennett, D.Sc, M.A., D.I.C., F.R.Ae.S., F.Inst.P., stated the case for the Gyrodyne. Raoul Hafner dealt with the solutions in- corporated in the Bristol 171, and J. S. Shapiro, Dipl. Ing. A.F.R.Ae.S., described the Cierva Air Horse and explained the considerations underlying its design. THE OPERATIONAL POINT OF VIEWW IXG COMMANDER BRIE, who is in charge of theB.E.A. Helicopter Unit, recalled that over a recent period of nine months, covering more than a thousandhours of experimental and scheduled operation, there was on no occasion a cancellation or interruption of flight due to thefailure of any purely helicopter component. ft had been proved that there is no fundamental deficiency in basic con-figuration, and that difficulties that had arisen could be attributed to lack of refinement in detail design. On the engineering side, he pointed out that the helicopteras a whole was particularly susceptible in terms of frequency and amplitude, to quite small departures from allowabletolerances on linkages. At present the working life of main rotor hinge bearings wastoo limited. Compactness had been achieved at the expense of reliability, comfort aud performance. Cost of operationwas increased not only through the enforced servicing, but by the interruption in the working life of other components whichwould best function if left alone. Ideally, all components should have a stated life, their replacement and interchange-ability being of primary importance. In addition, the design layout should be such as to allow concentrated effort to beapplied, thus reducing turn-round time. Accessibility demanded easily removable panels, jacking audhinge points, hand grips and foot rests. Suppression of friction demanded adequate lubrication, and if a grease gun was tobe used, correct positioning of the connectors was important. YEOVIL AREA MEAN DISTANCE FROM PO. = MILES PETERBOROUGH AREA MEAN DISTANCE FROM RO.M MILE POOLE K (6O,O00)K WEYMOUTH (22,000) Distances from post 100% _J 1 INITIAL COST ///////// 33% INSURANCE Z MAINTENANCE INTEREST ON CAPITAL Factors affecting direct flight cost. 5,000 Jb helicopter, 1,000 hr utilization. MAINTENANCE 21-7%V/ //////A 2-2% INITIAL COST V//////A 33% $2% 0. MAINTENANCE Y!%15-3% \////////A 28% 3-2% 35-6% INTEREST ON CAR INITIAL COST 21 % INSURANCE Y///////A MAINTENANCLV///////A DIRECT COST AT PRESENT EFFECT OF HALVING INITIAL COST EFFECT OF EFFECT OF HALVING INCREASING INITIAL COST ANDPAYLOAD BY 50% INCREASING PAYLOAD ' BY 50% \ /GT. YARMOUTH Y (57,0OO) offices to helicopter sites in Yeovii and Peterborough areas. . Sound engineering practice duringinitial design was vital. VV/C. Brie admitted that although itwas sometimes said that the helicopter is not difficult to fly, it would be anexaggeration to suggest that it is easy. The efficiency of the control system wasto some extent offset by the delicacy re- quired in the co-ordination of individualcontrols, lack of uniformity in sensitive- ness and "feel," and the inability totrim for any prolonged period. Lack of a satisfactory trimming device for useduring flight necessitated the employment of the azimuth control, thus restrictingadequate control response to gusts, and adding to difficulties of night and blindflying. The psychological aspect of helicopterpilotage needed to be explored^ for the mental capacity to think might notalways be in step with the physical neces- sity to act. Operating (rom confined areas de-manded rapid rate of climb at a steep angle and slow rate of descent at lowforward speed. These requirements were functions of power and disc loading re-spectively, the desirable values of which should not exceed 10 lb per h.p. and 2 lbper sq ft respectively. For safety the view from the pilot'sseat must not be impaired by the ex- ternal effect of rain or by internal mist-ing. This was particularly important during night and blind-flying operationsat low altitude. 20
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