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Aviation History
1949
1949 - 0172.PDF
FLIGHT JANUARY 27TH, 1949 HELICOPTER OPERATIONS Some Problems and Prospects : Useful Data from Operations by the B.E.A. Experimental Unit : Means of Reducing Costs IN the Library of the Royal Aeronautical Society on Saturday,January 22nd, Mr. N. E. Rowe delivered a very interestingpaper to the Helicopter Association. Since, in his view, the important helicopter developments in this country would be con-nected with transport, Mr. Rowe confined his attention to the operation of the helicopter for the convenience of passengers andgoods on scheduled services. He opened his paper, in which the views expressed were entirely his own, with a statement and dis-cussion on operating requirements. * In recognizing those characteristics of the helicopter which offeredsuch potential advantages—its ability to fly slowly and to hover, to use small and restricted areas for ta"ke-off and alighting andto move direct from point to point in threex dimensions, we had also to recognize that it was a comparatively short-range vehicle up to, say, 250 miles. It was, he said, on such ranges that it offeredIts most effective competition to existing means of transport in this country, whereasfor longer ranges the advantage tended towards the fixed-wing aircraft. Short-rangeoperation demanded regularity and punc- tuality, as serious late-running or cancellationof flight on a short route had more serious immediate effect than delays on a longer route, and unless the means of transport for such journeys was reliable it would not beaccepted as a convenient means of communi- cation. Short-stage journeys invited also close comparison withsurface transport in safety, regularity, economy and convenience. Thus, to become effective, helicopter operations in a country likeours must be no more affected by meteorological conditions than other surface transport. That was, he said, a fundamental require-ment. In addition, operations should be as readily performed by- night as by day. The third most important requisite was a relatively large numberof rotorstations, a term used by the lecturer for landing areas, equipped tc a standard necessary for regular and punctual operationsin all conditions. Although the helicopter would be used where it would show to best advantage, possibly over water or difficultcountry, journeys would still be "local" and the safety standard would be judged by surface transport rather by than air. Moreover,the ability of the helicopter to hover and move vertically without forward speed automatically laised the safety standard to a highlevel and it was one of the major problems of operation to maintain that. The firm essentials, in Mr. Rowe's opinion, were good blind-and night-flying characteristics, especially in regard to stability and control in smooth or rough air, cockpit visibility and layout. Itwas also important, he said, to have a "means of navigation from point to point in LFR conditions with a high standard of reliability.Other necessities were satisfactory recognition and let-down aids at alighting points in IFR conditions, good flying characteristicsin rough air, adequate performance in regard to the character of the terrain, including the case of engine failure, the requisitestandard of airworthiness, adequate means of air traffic control, the requisite operational standards and effective maintenance ofall equipment. Mr Rowe thought that the standard of regularity and punctuality should be not less than that of existing surfacetransport travelling over comparable distances, and, in general, a standard better than, say; plus or minus six minutes on a one-hourjourney might be maintained on about 90 per cent of occasions. In order to make fares comparable with alternative means oftransport, taking into account the greater convenience of saving time, economic measures should include lowcapital charge -of the machines, first-class reliability, economical maintenance and ahigh annual transport capacity for a given first cost. This depended on the productof utilization, block-speed and payload. Since short-stage operations required a largenumber of rotorstations, they should be necessarily simple, cheap and easily main-tained and serviced. Large cities would have several to cater for traffic in variousdirections, a system which might be far cheaper than a complex system of air trafficcontrol The whole matter, he said, needed careful study, keeping in mind the essentialneeds of regular operation in all except the most severe meteorological conditions, andbasic economy. In choosing routes to give maximum advantages the preliminary aimshould be to save one hour on a 100-mile journey compared with the best surfacetransport, taking full account of surface times to rotorstation or railway station. AsWell as siting rotorstations near to city centres, tht study ol helicopter movements TVfR. N. E. Rowe, C.B.E., D.I.C., B.Sc,1TA A.C.G.I., F.R.Ae.S., Whit.Ex., is Controller of Research and Long TermDevelopment in the British European Airways Corporation. During the warhe was Director-General of Technical Development in the Ministry ofAircraft Production. SUCTIOI A suggested instrument panel layout for night- and blind-flying helicopter operations. into and away from busy airports should be made, as although noscheduled helicopter services from city centre to airport were en- visaged, taxi services from city centre to airport would be developed.Speaking of the relationship between frequency and journey time, Mr. Rowe said that as a general rule the shorter the time thehigher should be the frequency of the schedule, and frequency had a strong bearing in deciding the size of aircraft needed andin attaining the maximum annual utilization for economical running. In considering services in the Scottish Islands and Highlands, andin heavily built-up areas, the minimum requirement for regular scheduled helicopter transport operations was a twin-enginedmachine. The standard of comfort, he said, should be what was acceptable for a short journey, bearing in mind that it would havebeen by the* alternative a much longer and more tedious and perhaps difficult journey.It -was also necessary that the weight of furnishings and amenities should be kept toa minimum. Commenting upon safety and regularity,Mr. Rowe quoted Dr. Edward Warner's ob- servation in his Wilbur Wright Lecture in1943 that regularity and safety obviously had an inverse relationship. Although Dr. Warnerwas discussing the problems of fixed-wing aircraft, Mr. Rowe thought that it wasequally true of transport by helicopter. A helicopter pilot would continue to fly in com-plete safety at much lower meteorological visibility than was possible with fixed-wing aircraft because he did not rely on speed for sus-tentation and generally flew at a much lower height. He then gave an interesting example of the B.E.A. dummy mail operation inDorset in February and March, 194S, when the total irregularity due to weather amounted to 3 per cent. Of that, 2 per cent wasdue to low clouds on high ground over which the route passed and 1 per cent was due to sea fog. On many occasions visibilitywas down to a quarter of a mile locally without hampering opera- tions which were limited to contact flying only. Conditions in theworst months of the year in these islands were so poor, however, that 100 per cent regularity could be obtained with safety only bysolving completely the problems of blind-flying and navigation, blind-approach and landing by day and night. It was encouragingto hear from Mr. Rowe that the results of the work already done by the B.E.A. Experimental Unit showed there was good prospectof realizing these objectives in a reasonable time. The Unit had, by November 30th last year, completed 87 hours of night- and blind-flying, of which 4-5 hours had been cloud flying by day. The longest continuous time in cloud was 20 minutes, but that couldbe increased with practice, although the strain of flying-blind the S.51 was higher than a comparable fixed-wing aircraft. All instru-ments were standard except the Artificial Horizon, which had adjustable pitch-and-roll datum lines. B.E.A.C. Night Operations An experimental scheduled night operation was completed in thefive weeks ending on September 23rd, 1948, consisting of the return flight Peterborough-Downham Market, a distance of 58 miles, whichwas made on four successive nights each week and on which 100 per cent regularity was obtained. The recognition aid was an occultingbeacon made up of five standard sodium runway lights arranged to give a 2-second cycle. Wind direction and illumination for land-ing was given by a " Wiggimac " which illuminated at low intensity an area about 100ft in diameter of whichthe circumference was marked by a band of white on the ground. Wind directionwas shown by a shadow bar and approach light. This equipment was satisfactory andthe pilots were able to land without dazzle. For point-to-point navigation an adaptationof the standard SBA/VHF equipment was used, but that was not satisfactory and itis hoped that the Decca Track Guide, when available, will become the standard meansof navigation. With regard to punctuality and wind allowance, the lecturer explainedthat the higher the scheduled mean block- speed the less margin there was of cruisingspeed available to cope with strong winds. It was therefore necessary to have seasonalschedules so that a tolerance of plus 10 per cent of scheduled elapsed time was exceededon only 1 per cent of occasions in any scheduled period. This would correspondroughly to punctuality on 95 per cent of occasions. After enumerating the differences betweentraffic control at airports and at rotorstations;-
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