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Aviation History
1945
1945 - 2015.PDF
398 FLIGHT OCTOBER IITH, 1945 DE HAVILLAND DOVE DIRECT OPERATING COST PER AIRCRAFT FLYING HOUR ffNCl PER PA55ENGER-MHE Hourly Flying Expenses. Fuel and Oil ;—-An average allowance is made to take account of the additional fuel usedin taxying, take-off, etc. Maintenance :—(a) Airframe. £1.25 per air-craft fly;ng hour per 10,060 Ib. of airframe (b) Engine. £1.5 per aircraft flying hour per 1,000 cruising B.H.P Crew :—Captain—salary, £850 per annum. Radio operator—salary £550 per annum.Insurance and expenses—0 15 of salary. Flying time per annum—850 hours. *. . , „ . £850 x 1,15 £550 x 1.15 850 Total hourly flying expenses ... ... Dove. Cost per flying hour. £2.31 £0.43 £0.48 £0.91 £1.15 £0.74 £189 £5.11 Dragon Rapide. Cost per flying hour. £1.98 £0.31 £0.39 £0.70 £1.15 _ £1.15 £3.83 FIXED CHARGES Depreciation :—.Five years' life with 0.25 residual value at end, giving £150 per £1,000 of aircraft cost with spares cost, divided by the total flying hours per annum Insurance '.—-0.08 per annum of the average insured value of the aircraft (taken as 0.70 of the first tost) to include both compre- hensive and third-party cover, giving £56 par £1,000 of aircraft first cost, divided by the total flying hours per annum interest on Investment :—0.05 per annum on the average value o' the investment (taken as 0.70 of the first cost of the aircra't with spares) giving £35 per £1,000 of aircraft first cost divided by the total flying hours pe.~ annum ... To"-a! fixed charges Direct operating cost per aircraft flying hour (sum of hourly ftying expenses and fixed charges) Dove (Dragon Rapjde t per flyro^jCost per flying hour. ! hour. £2.25 £0.70 £0.52 £347 £8.58 £0.99 «C0.3l £0.23 • £1.53 £5.36 This example assumes a utilisation o! 1,000 hours per annum. accumulators, whilst the pneumatic supply is from dupli- cated ail bottles maintained by duplicated Heywood com- pressors at a maximum pressure of 6oo lb /sq. in for operation ol the undercarriage, flaps and wheel brakes. General performance of the Dove is excellent, but import- ance has been attached to single-engine performance and the latest requirements of the Air Registration Board are fulfilled. On full load the machine will climb to 7,000ft. at a rate of, 120ft. per minute on one engine at normal climbing power, and the absolute ceiling in that condition with full load is 10,000ft. Additionally, if when taking off one RECOMMENDED CRUISING . _, SKED f©ft tONO OVERHAUt MtTREi PSR1ODS (15* SHP/ENG AT SO0O ft. 1515 m-»47*i TAKi-GF* POWIR) ^1 KfMtSStBU WEAK * r ..WXTUjie CRUtywG POWER P«BHP/ECAI MOO ft TAKf 0^ POWfR) (Left)Pence per passenger mile. (Above)Pence per passenger mile THOUSANDS Of MILES P£A ANNUM WEIGHTS Tare weight Radio Crew of two ... Fuel, 71 galls., for 500 mile; still air range Oil, 10 galls Payload A)l-up weight Standard 8-passenger version. Ib. 5,138 100 360 512 90 1,703 8,000 Standard version without seats and toilet Ib. 5,133 too360 512 90 1,835 8,000 With no sound- proofing or upholstery. Ib. 4,963 100360 512 90 1,975 8S000 ASSUMPTIONS Cruising fuel consumption, gall/hr. Cost of fuel per gall. Cost of oi' Air frame weight, Ib. Total cruising B.H.P Crew First cost of aircraft (estimated) . Spares carried Dragon Rapide 18 2- 0.06 of fue1 cost per hr. 2,500 260 21 2/- 0.06 of fuel cost pet hr. 3,430 J20 2 £12,500 0.20 of first cost of aircraf'. £5,500 0.20 of first cost of aircraft. Variation of cruising speed with altitude and power. engine should fail at the moment of starting to climb the aircraft will continue climbing and will attain a height of 50ft. within 1,230 yards of the start of the take-off run; alternatively, the Dove can be landed and brought to rest in less than that distance. It is noteworthy that the de Havilland airscrews are equipped for negative thrust braking which not only reduces the landing distance considerably and so spare the wheel brakes for the relatively light duty of ground manoeuvring, but also provides very useful advantage for emergency landings or alighting on very short airfields Because costs vary widely between different countries and for different operating conditions and changing price levels, it is very difficult to give an overall and accurate guide to the cost of operating a particular type. The air- craft manufacturer can, however, supply a good deal of the data for costing an aircraft, but he is obliged to make assumptions for other items such as maintenance, salaries, price of fuel, etc., so that, although the cost calculations estimated by de Havillands and reproduced here are unlikely to fit an actual case, they should serve as a useful guide if the individual operator can readily substitute speci- fic figures. Only direct operating costs are being considered, administration, road transport, plant and bnildings, and all other indirect costs being excluded. The figures are based on British price levels obtaining early in 1945 and adjust- ments should be made accordingly. As mentioned, because the province of the Dove is so near that of the well-proved Dragon Rapide, it has been thought desirable Oy the makers to show figures for the two types side by side.
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