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Aviation History
1948
1948 - 1772.PDF
496 FLIGHT OCTOBER 21ST, 1948 Some Economic Factors in Civil Aviation* Comparative Transport Possibilities : The Prospect for Helicopters : Performance Comparisons of Hypothetical Aircraft with Various Power Plants A something ot a diversion, but nevertheless with a closeconnection to his cost analysis, Mr. Masefield nextexamined the question of average incomes, the valueof a working hour, and from those calculated the price which" should be paid for time saving in travel. It seemed thatthere were about 660,000 wage earners whose average earnings per working hour were just over 20s. Therefore, if the averageman of this number could save an hour by flying, it was worth at least £1 to him. Moreover, the advantage of thehelicopter in achieving a high block speed over a short range was worth £1 higher fare per hour saved. Some amusing dia-grams were offered to illustrate the journey times for various means of transport. A series of curves had also been plotted, from which itappeared that up to 215 miles the helicopter was the fastest means of transport; thereafter the fixed-wing aircraft wassuperior. For a journey of 25 miles the helicopter saved 24 minutes over the bus and cost 13s 5d more (five times the busfare). Even so, the helicopter was likely to lose money. The helicopter's saving in time over the bus cost £1 13s yd per hoursaved. On the assumptions made, the helicopter was not worth operating in competition with a good bus service for soshort a distance as 25 miles. Its saving in time in comparison with the train was insignificant—7 minutes—and the cost ofsaving it was very great, a rate of £3 8s per hour saved. There- fore, one might conclude that the helicopter could not competeon the fares quoted for a 25-mile inter-city journey. If one assumed that an hour saved was worth £1, then thehelicopter came into its own compared with the bus for dis- tances of more than 100 miles. At 100 miles, for instance, thehelicopter saved 2.6 hours and cost £2 6s more than the bus for the journey. A depressing fact was that compared with thetrain the helicopter never cost less than an extra £1 gs for an hour saved—and that at the 215 miles distance at which thefixed-wing aircraft began to take over. Fares of less than i8d per passenger mile were too low to 2 HOUR JOURNEY 53 88 17O MILES 2-65 HOUR JOURNEY 66 112 215 MILES 3 HOUR JOURNEY <i=--':;:. 75 13O 25O «*§,-' 3OO MILES Some journey times for various means of transport. achieve without loss with the helicopter in its likely state ofdevelopment in the next few years. Although the helicopter was both faster and cheaper peT hour than was the fixed-wingaircraft for distances up to 200 miles, the comparison was merely one between losers over such distances. The answer tothe question "what can be done to bridge the gap between competitive fares and operating costs for distances up to 200miles? " was, Mr. Masefield suggested, through mail. A fast and frequent mail service between city centres would justifya relatively high but not uneconomical mail rate. A network of inter-city helicopter services in the United Kingdom pro-viding much faster postal deliveries than could any other means of transport up to 200 miles would, Mr. Maseiield sub-mitted, be well worth the rather high mail rates of the order of 20s per ton-mile which would be necessary to prevent losseson a passenger fare of 6d per mile. The conclusion was that the helicopter could be useful up to 200 miles if air mail aid wereenlisted. Thereafter, the fixed-wing aircraft took over, the turboprop offering the best economic prospects of all whendevelopments in air traffic control came forward. The jet was faster, but even at advanced standards was slightly moreexpensive per mile. Both would be able to offer competitive service at speeds and rates which would outclass rival meansof transport once the problems of diversion and stack-up had been solved. An interesting sidelight on these conclusions was that theaverage passenger journey on British internal airlines was 150 miles—within the helicopter field—whereas the average pas-senger journey on British Continental services was just under 500 miles-—well into the fixed-wing field and close to the mosteconomical stage length of the Ambassador. Long-Range Transport Mr. Masefield next turned his attention to an analysis of ahypothetical long-range Commonwealth and Empire Orion air- craft, the four versions of which differed chiefly in the typeof power unit fitted. It was assumed, however, that some liberties had been taken with the airframe of the pure-jetOrion to improve its high-speed qualities, and also the passen- ger comfort when encountering gusts or turbulence at highspeeds. The wings and tail surfaces were assumed to be swept, and their thickness-chord ratio reduced. There remained theproblem of where to find storage space for all the fuel required, and external wing-tip tanks might be necessary. The fourversions analysed were as follows: — (1) Orion I. Four 500 b.h.p. Orion Major standard pistonengines. (2) Orion II. Four 5,750 b.h.p. Orion Maximus compoundpiston engines. (3) Orion III. Four 5,750 e.h.p. turboprop engines, 4 Orion IV. Eight 7,500 1b static thrust plain jet engines. Eight engines in the case of the Orion IV provided a totalthrust available for take-off equal tc that produced for the other variants. Eight units had been chosen because of thebenefits to be gained by operating on a smaller number of engines during descent, diversions to alternate airport andduring stand-off. Cruising at a high output from less thai) the full number of engines was a far more economical methodof cruise control than throttling a smaller number of engines of equivalent total power. A weight analysis and comparativeperformance data for the long-range Orions are given in tabular form on the next page. The lecturer had already pointed out that turbine-poweredaircraft could come into their own only as a result of improve- ment in air traffic control. > Assuming present operating standards for all except theOrion IV, and applying specialized but practical operating *This instalment concludes our summary of Mr. Peter Masefield's l'JM BritishCommonwealth and Empire Lecture to the Royal Aeronautical Society. Some of the more technical aspects merit a closer study, and we hope to return to them at a future date. B 22
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