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Aviation History
1949
1949 - 0174.PDF
-n6 FLIGHT JANUARY 27TH, 1949 Helicopter Operations in the most favourable sites action must be taken now on broad andliberal lines. That would depend to a degree on the investiga- tion into the accuracy of the. Decca Track Guide System of navi-gatio.n to be initiated early this year. Preliminary action could be started now, however. The potential use for the helicopter inthese islands was a direct point-to-point link between all major towns and cities. THE DISCUSSION The lecture was very well attended, but it was obvious that mostmembers of the audience were helicopter people rather than potential operatprs of helicopters. Mr. H. A. Marsh was in the chair, andS/L. Basil Arkell had volunteered for the task of operating the lantern.Mr. Rowe had to present a summary of his paper, which is a very long one, but he succeeded in covering all the main pointsin the time available. A very good discussion followed the reading of the paper, asseveral points turned out to be controversial. For example, Mr. Rowe's suggestion that helicopter maintenance time could be greatlyreduced if a system of sealed service were introduced so that com- ponents need not be touched, except for ordinary servicing, untilthey had completed a pre-determined life, when they would be replaced by new or overhauled components.Mr. O. L. L. Fitzwilliams thought such a procedure would tend // Y /( 0 HEL1 SLOCKS 3LOCK « CQWSE >(<EECVR m / /. O M.RH i . 5 6 7 TRAIN TIME (HOURS) 1O The advantage of the helicopter over the train in terms of time saved against train times. .. .. : ' ' to cause stagnation in design, but Mr. Rowe disagreed. He thoughtthat, on the contrary, it would encourage design by finding the snags before the machine went into service. . •On the subject of navigational and let-down aids, the suggestion was made that it was high time we began thinking about the sortof aids that will be wanted when helicopters go into service. Mr. Peter Masefield expressed the hope that helicopters would be ableto do without any other navigational aids than the Decca, and that at the "rotorstations" (a term coined by Mr. Rowe, which wasgenerally welcomed) it might be possible to use lights, thus avoid- ing further additions to the already cluttered aids for fixed-wingaircraft. If, he said, we once made up our minds that we might be wanting these aids, then certainly we should saddle ourselveswith them, and that ought to be avoided. Some of the speakers argued that Mr. Rowe had been too modestin certain of his stated requirements. For instance, the size of rotorstation asked for was considered too small if space had tobe found also for parked helicopters. Also, in the matter of heli- copter size, some thought that if 12-15-seaters were likely to beeconomic at the start of operation in four years' time or so, then WF ought to be thinking of 40-50-seaters very soon.The cost of elevated rotorstations was held by one speaker to be likely to be fantastically high, and for the forthcoming exhibitionon the south bank of the Thames, a floating rotorstation on the river was suggested. As to the siting of such stations, Mr. J.Shapiro agreed with the lecturer that there were few within a mile of Charing Cross, with one exception : Charing Cross. He thoughtrailway stations were the logical sites for rotorstations, but Mr. Rowe replied that B.E.A. had consulted railway people, and hadbeen asked if there was any possibility that "these things" might have mishaps and occasionally come down on the railway lines in frontof a train! A FINE FILM SHOW After an interval for tea, sorffc very interesting cine films wereshown by Mr. Colin Cooper. First came a series of " shots " of Mr. Marsh flying the Skeeter and Air Horse. Much amusement wascaused when he was shown flying the small machine literally into a hangar at Eastleigh.Mr. Colin Cooper then projected a long colour film which he made on his recent visit to America. Those who had expected todiscover from the film which helicopter configuration is likely to be the most successful were disappointed. All manner of types" evoluted " (or should it be " revoluted " ?), and from the point of view of manoeuvrability there appeared little to choose betweenthem. Perhaps the most manoeuvrable was the Kaman 190, whose pilot did the most astounding things with his machine. But thelittle, tandem-rotor JOV-3 also handled remarkably well, and even took-off and landed backwards. Of the superimposed, contra-rotatingtypes, the Jensen was extremely manoeuvrable and, it is said, easy to fly. When it came to stability, it would appear that the Hiller360, upon which United Helicopters vice-president, Mr. Chadwick, commented, held the lead, with its aerodynamic servo controls. Butobviously there is still no finality in the matter of helicopter con- figurations. % The meeting was an unqualified success, and the Helicopter Asso-ciation of Great Britain is to be congratulated, not only on obtaining such a distinguished lecturer, but also on the enthusiasm of itsmembers, who never seem to mind giving up their Saturday after- noons if the subject is helicopters. That spirit, it is to be feared, haslargely departed from the fixed-wing aircraft field, which is some way out of its pioneering days. Timio-si Pt:it< 11 \IU*I:I» 4,000 h.p. WASP MAJOR SOME details have been released concerning a compoundedpiston engine built for the United States Air Force which de-livers 4,000 shaft horse power and several hundred pounds of thrust. The unit is basically the 28-cylinder Pratt and Whitney Wasp MajorR.4360, but it is known in this case as the Major-VDT (Variable Discharge Turbine). It operates in conjunction with a two-stageGeneral Electric variable-discharge turbo-supercharger. It is claimed that a large proportion of the energy available in the engine'sexhaust gases have been effectively reclaimed and efficiency has been further improved by providing for inter-cooling of the superchargedcombustion air. * General Eleetric's CHM-i two-stage supercharger utilizes the ex-haust gases in two ways: the first stage drives the supercharger for all combustion air required by the engine; the discharge gases fromthis stage are then fed through a variable-area orifice to a second stage, the shaft of which is geared back to the main crankshaft ofthe engine. The purpose of the variable orifice is to obtain the best division of exhaust energy between supercharger and residualthrust. Another feature of the Major-VDT, believed to be unique, is themethod of control of engine speed. A conventional tyge of throttle is used only for low-powers while for higher power operation, enginepower and speed are described as being regulated automatically by controls which enlarge or restrict the variable-area discharge nozzle.This determines the Amount of exhaust energy extracted by the turbine for supercharging, while the quantity of air delivered to theengine in turn fixes its power output. The elimination of throttling in operation is said to rednce air entry losses.Many of the main units of this newly developed variant of the Wasp Major power plant are of standard type and as such arebacked with a great deal of operational experience. The Wasp Major is the most important of very high-powered American engines.British operators will soon have experience of Wasp -Majors when the Stratocruisers, which they power, are delivered to B.O.A.C.An official 150-hour type test was completed by the Major VDT in August of last year. To make provision for the increased poweroutput at the airscrew shaft certain engine components have been strengthened, while the elimination of the normal type of super-charger is, of course, a major modification. The overall weight of the engine has been increased as a result of,these important altera-tions, but the power/weight ratio has been improved. The United States Air Force has shown great interest in com-pounded engines for some time past, and the possibilities of a system very similar to that used for the Major-VDT was tried with theAllison V-1710 about three years ago. A more simple system for re- claiming exhaust gas energy and feeding it back direct to the air-screw shaft was described in Flight, October 7th, when reference was made to the Wright Turbo-Cyclone. There is a strong tendencyin America at present to give the impression that there is virtually no difference between a piston engine associated with exhaust-driventurbines and a turboprop unit. Moreover, to add to the confusion Pratt and Whitney have named their home-built Rolls-Royce Nenes" Turbo-Wa.sps." Thus, the Turbo-Cyclone is a perfectly normal radial piston engine with small exhaust-driven turbines, and theTurbo-Wasp is a pure turbojet. The Wasp Major, which is a com- pounded unit, somewhat comparable with the Turbo-Cyclone, hasto be content with the addition of VDT after its name to indicate its turbine association. - Aero Digest, states that the first installation of the compoundedWasp Major-VDT is in the modified Boeing B-50C bomber which may be designated the B-54. The increase of 15 per cent inpower brings the take-off output to approximately 4,000 s.h.p., and the maximum cruising power at 30,000ft is slightly under 3,900 h.p.Specific fuel consumption decreases with increase in altitude, being* at sea level cruising conditions, 0.51 lb/h.p./hr, and at 30,000ft0.40 Ib/h.p./hr.
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