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Aviation History
1945
1945 - 0338.PDF
I78 FLIGHT FEBRUARY 15TH, 1945 CARCO AIRCRAFT Cimens en: Wing span .. Overall length Overall bright (overfin) Wing arci Aspect ratio ... Volume main cargo hold Volume rear cargo hold ... ... ... Main cargo hold, 31ft. 8in. long, 8ft. wide (at 24in. af>ove floor) Bfl. Bin. high (minimum) Wheel track Weights and Loadings: All-up we.ight Tare weight ... Crew (two) Disposal load Power loading 'T.O. power) Wi ld Cmisini' -j»'.<l- 600 B.H.I-, IJ.'I >-ii«i:i> 600 700 „ Stalling speed 6ervice ceiling Initial rate of climb Take-off to clear 50 feet ('onrrete runway Grass runway ... Landing ovei f>0 feet (at 27,500 Ib.) Cruising range (standard tanksl Cruising height Perrormanc*: I .T). power) T.O. [lower) T.O. n.,m-n 98ft. rtRft. 4in. 21ft. 8in. 1,405 so,, ft. (J.H4 2,02') m. ft. 340 cu. ft. 27ft. 6in. ; 0,000 lb. 400 11). 12.8 ln./B.H.P. 21.4 Ib./sq. It. 144 m.p.h. 158 m.p.b. 17(1 m.p.fc. 07 ni.p.h. 16,000ft. U00 feet pe: minute 050 yards 700 yards 700jards 1.400 miles 5.000 feet. General arrangement drawings, dimensions, weights, load-ings and performance of the Bristol Freighter. As regards airframe maintenance, estimates based on long experience indicate that the labour required will not exceed one man-hour per aircraft hour flown for a fleet of 10. Taking supervision, stores, etc., into account, it is esti- mated that the cost per aircraft / hour flown woujd be about 5s. Provision is included in the estimate for four sets of tyres per annum (£200) and ^300 for miscellaneous replacements. Normal daily inspection as well as sparking- plug, magneto and filter examinations at 100-hour periods are assumed. Power^lants would be removed for over- haul every 600 hoiy*7 Inspection and power plant changes come to an estimated total o( 5s. per aircraft/hour flown. The cost of one engine overhaul, including replacement of the usual consumable parts, is estimated at /250 ; to which is added £130 for replacement of major components. The cost per aircraft for each 600 hours is thus equivalent to 26s. 8d. per aircraft/hour. Depreciation is the next item. The airframe and air- screws are assumed to have a useful life of 15,000 hours, giving an hourly depreciation provision of 26s. 8d. The useful engine life is taken as 7,500 hours, giving an hourly depreciation provision of 13s. ><fT The cost of airport facilities, ground services, hangars, administrative and selling expenses and other indirect charges will obviously fluctuate widely according to the route, utilisation, block stages, etc. It has been assumed that airport fees will average £b per landing and that all other expenses will cost £3 per hour flown per aircraft. For a passenger aircraft the average load factor- is generally taken as 65 per cent., but there are no statistics in respect of freight air- craft. In the Bristol Freighter its capacity, i.e., its payload, is limited only by its maximum permissible all-up weight and not by the cargo hold capacity. Aaaverage volume / weight ratio for general merchandise is 120 cu. ft. per ton, so that the Bristol Freighter has capacity OH a cubic basis for the carriage of nearly 20 tons. The average volume / weight ratio used by aircraft operators is. JQ lb. per \ I ^CONTROL,DUCT 8'-O"i BRISTOL FREIGHTERTYPE 170 Two Bristol New Perseus9 - cylinder sleeve valve engines, rated at 1,175b.h.p. for take-off. BLOCK DISTANCE — MILES Graph showing horsepower-required plottedagainst distance and speed. cu. ft., so that even on this basis there is capacity for more than 10 tons. Both calculations show a considerable margin above the optimum disposable load of 11,000 lb. The designers believe that an average payload factor of at least 80 per cent, is possible of achievement. In calculating block speeds it has been assumed that 15 minutes will be required, for taxi, take-off and climb ^cruising height, and that in this toe 10 miles will be flown on course. For simplicity of calcula- ^ tion it has further been assumed that the machine will fly at a constant weight of 30,000 lb. and that its speed will not increase with con- sumption of fuel. Actually it would increase—our Horace says so. The calculations provide for a utilisation of 3,000 hours per air- craft p.a. We have commented on this factor earlier in our article. There is no reason at all why 3,000 hours should not be flown or even exceeded. It would require proper organisation, day and night ser- vices, and a close study by experts of pre-loading into suitable light- 180 160 HO 1OO (/ 1// • • — — • = B> 1 7OO _—<^ eoo • i •— 5QQ
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