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Aviation History
1948
1948 - 1724.PDF
464 F LI G HT OCTOBER 14TH, 1948 Some Economic Factors in Civil Aviation . ing costs of a large aircraft tended to be less per ton of grossweight—80 per cent—than those oi a small aircraft. From typical economic U curves plotted for the variousaircraft could be read the stage duration over which an aircraft could be flown economically at the lowest fares regardless ofwind—a duration ranging from 2.1 hours for the Dove up to 12.1 hours for the Brabazon I. Turning from the cost to the important matter of revenueand profit and loss account, Mr. Masefield said that revenue was directly proportional to stage length and load factor, anddependent on the type of traffic. Representative figures for present-day fares and charges could be broken down as shown £2OOO £1000 £eoo £6OO REPRESENTATIVE REVENUE FIGURES 0 § a. wa § 1g 1- 'i £4OO £3OO £2OO £1OO £8O £6O £4O £3O £2O RAPIDE DOVE DAKOTA AMBASSADOR CONSTELLATION ORION £•10 5 7 9 11 HOURS BETWEEN LANDINGS Operating costs per hour versus hours between landings for various utilizations between £00 and 4,000 hours per year. in the table. Figures were founded on the rather high inter-national mail rate of six gold francs per tonne-kilometre, and assumed a io per cent reduction in half the passenger faresat representative European rates for return tickets. For the seven aircraft, normally equipped, results indicated an averagerevenue of 5s 5d per ton-mile of combined payload for the large aircraft, to 6s per ton-mile of combined payload for themedium types, and 8s per ton-mile for the smaller types. Although hour charts read in conjunction with hour curvesgave all the answers for any selected stage length and one condition, for quick appreciation Mr. Masefield plotted theoperating costs and revenue of the seven aircraft related to stage length in still air. From 215 to 600 miles stage lengththe Ambassader was the most economic of the aircraft re- viewed, and despite its higher cost was cheaper to operatethan the Dakota for each ton of payload or for each passenger over all stage lengths. The higher the head wind the greater ScheduledOperations for : Representative air- craft involved Average weight of each passenger (with baggage, and consumable stores). Average European Passenger Fare per mile. Mail rate per ton mile Freight rate per ton mile. Combined average rate of revenue per ton mile (at 65 per cent passenger load factor). Long Stage Services Brabazon IB Orion I Constellation 250 Ib (9 passen- gers per ton of payload) 6 pence (4s. 6d. per ton of pas- sengers per mile) 16 shillings 3s. 4d. £0.27 Medium Stage Services Ambassador Dakota 225 Ib <tO pas- sengers per ton of pa/load) 8 pence (6s. 8d. per ton of pas- sengers per mile) 16 shillings 5s. Od. £0.30 Snort Stage Services Dove Rapide 200 Ib (It.2 pas- sengers per ton of payload) 8 pence (7s. 6d. per ton of pas- sengers per mile) 16 shillings 5s. Od. £0.40 the Ambassador's advantage. For stage lengths between 6ooand 2,350 still air miles the Constellation was the most economic proposition. The Brabazon I had the field on itsown from 2,350 miles up to its maximum of 3,920 miles stage length. For scheduled operations in still air profits couldbe made on stage lengths approximately as follows: — Rapide 190-290 miles Dove 270-650 miles Dakota 310-980 miles Ambassador 220-980 miles Constellation .' 335-2,700 miles Brabazon I 750-3,920 miles Against head winds both the amount of revenue and the economic stage length would be reduced. In the present state of the art, and taking into account average winds but not the amount of traffic offering, the most economic size of air- craft for a non-stop stage length of: — 100 miles is about 4,000 lb (two pass.) 500 miles is about 30,000 lb (24 pass.) •. 1,000 miles is about 85,000 lb (36 pass.) 2,000 miles is about 180,000 lb (56 pass.) "•—• •. ~ *.-.,;' ;.••-' 3,000 miles is about 280,000 lb (84 pass.) • ; 3>5°° miles is about 325,000 lb (112 pass.) •-• '-' Relating these figures to the severi selected contemporary types of aircraft, the most economic stage lengths over which each could be operated were as follows: — Aircraft Rapide ... ..?•• Dove DakotaAmbassador Constellation Orion 1 Brabazon 1 Still Air and 60 m.p.h. Headwind 290 to 144 statute miles 444 600 700 1,880 2,170 3,630 , 288 . 390 , 555 , 1,440 , 1.760 . 3,000 Block Speeds 103 to 51 m.p.h. 148145 219 225 276 300 , 96 „, 95 ., , 174 „ . 203 „ , 224 „ . 248 .. I:£O-9 1 ;£O-8 I '. £O-7 i I £O-6 £0-5o Z£O-4 gj£O-3a O .» £O2 m 3 £O-1 RAPIDE DOVE DAKOTA AMBASSADOR ~—•—- CONSTELLATION ORION —BRABAZON 1 30OO HOURS ANNUAL , UTILISATION. PASSENGER LOAD IN STILL AIR \ SHORT RANGE REVENUE MEDIUM RA! REVENUE LONG RANGE . REVENUE y 5OO 1OOO 15OO 2OOO 25OO 3000 35OO 4OOO STAGE LENGTH - STATUTE MILES Economic stage length curves for contemporary types. (The lowest point of the curve indicates the stage length at which the most economic performance is achieved in still air.) If lowest cost per revenue ton-milewere plotted against stage length, assum- ing the use of the most suitable size ofaircraft, it could be seen that the best stage length to fly for the lowest operat-ing cost per ton-mile (but not necessarily the highest profit or least loss) lay be-tween 1,800 and 2,000 stage mites in still air, using an aircraft of about 110,000 lbgross weight. Break-even fares could be reduced to about 3d per passenger-mik. The most important conclusion whichconcerned operating costs and revenue was that, provided an aircraft was=matched to a route in terms of the most economic size for the stage length to beoperated, taking into consideration the prevailing winds, and provided that theaircraft was flown at a reasonable height, utilization of air transport, even withpresent types of commercially efficient aircraft, could be made to run at a profitat the present (high) fares. A prominent reason for the narrow boundary betweenprofit and loss lay in the overheads and in the operation of stage lengths unsuitedto the sizes of aircraft used. Although weighted down with over-.." B 18
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