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Aviation History
1951
1951 - 1630.PDF
i..:. August 1951 229 level through the inverse ratio P/PO for 100 per cent bags it was possible to assess the lift at sea level; and (6) by conver- sion of lift to helium-capacity volume was obtained. Stage 2 (Secondary).—In assessing the performance of this airship, the Stage 1 breakdown is again checked against the initial commercial specification. The calculated volume was 11,000,000 cu ft. Herr Hans Ebner found by practical experiment that a finess ratio of 5 or 6 to 1 was best for the low speeds attained by dirigibles. In order to enclose 11,000,000 cu ft and maintain a shape fitted to quick production and slimness, this volume can be enclosed within the dimensions 980ft in length and 140ft in diameter. This space allows adequate engine-displacement, and accommodation for passengers, as well as ballast and tankage space. From previous airship figures it can be found that a drag-coefficient of 0.05 when used in the formula as follows:— Drag = KAV2/» gives T.H.P. = MYL*55O From this formula a series of anticipated performance figures at various altitudes can be calculated.Data at Sea Level:— Total lift 722,5001b Dead weight (for 7,500ft pressure altitude) .. 317,777 lbFuel and payload 404,723 lb Maximum diameter 140 ftLength 980 ft ALTITUDE v LIFT Altitude (ft) Sea Level 3,000 ... 5,000 ... 7.500 ... 10.000 ... 15,000 ... % Bags 100— 90 85 80 74 63 Max. lift (Ib) 722,500 650,000 615,000 578,000 535,000 455,000 Fuel (Ib) 100,000 100,000 100,000 100,000 100,000 100,000 Payload (Ib) 304,723 222,223 187,223 160,223 117,223 37.223 Payload (torn) 136 99 83i 72 52* 16* ALTITUDE/PAYLOAD/RANGE CURVES (Consumptions 0*5 Ib/b.h.p./hr. v =85 per cant) Spaed (Wt) At Sea 100 90 80 70 60 50 40 b.h.p. rqd. Level: 19.300 14,700 9.900 6.600 4.100 2.340 1,240 At 5.000ft: 100 90 80 70 60 50 40 17,400 12,700 8.850 5,850 3.650 2,100 1.110 At 10.000ft: 100 9080 70 60 50 40 14,500 10,600 7,400 4.800 3.025 1,740 920 Com. per hr (Ib) 9.650 7,350 4,950 3,300 2,050 1,170 620 8.700 6,350 4,425 2,925 1,825 1,050 505 7,250 5.300 3,700 2,400 1,513 870 460 With 10,000 Ib fuel load: range (n.m.) 520 612 810 1,060 1.490 2,140 3,225 575 710 910 1,200 1,640 2,380 3.950 690 850 1.080 1.460 1,980 2.870 4.350 pay- load (tons) 158 158 158 158 158 158 158 106 106 106 106 106 106 106 75 75 75 75 75 75 75 With 100,000 Ib fuel load: range (n.m.) 1.040 1.224 1.620 2,120 2,980 4,280 6,450 1,150 1.420 1.820 2,400 3.280 4.760 7,900 1.380 1.700 2,160 2,920 3,960 5,740 8.700 pay- load (tons) 136 136 136 136 136 136 136 83 83 83 83 83 83 83 52! 52^52 52 52 52 52 With 1SO.0OO Ib fuel load: range (n.m.) 1,560 1,836 2,430 3,180 4,470 6,420 9,675 1,725 2,130 2,730 3,600 4,920 7,140 11.850 2.070 2,5503.240 4,380 5.940 8,610 13,050 pay- load (tons) 113 113 113 113 113 113 113 61 61 61 61 61 61 61 30 3030 30 30 30 30 Item i of the specification calls for a payload of 50 tons minimum over a stage-length of 8,700 miles at 5,000ft pressure-altitude. By reference to the tables on performance it can be seen that the airship will fulfil these demands of non-stop flight:— Stage 3 (Schedules):— CASE A. Eastbound. London-Perth at iOjOooft. Wind com-ponent 4- 15 kt at altitude. Distance, 8,700 n.m.; air-speed, 40 kt long-range cruise; ground-speed av. 55 kt; flight time, 158 hr;Payload, 524 tons; endurance at 40 kt, 217 hr. Elapsed time, 158 hr. CASE B. Westbound. Perth-London at 5,000ft. Calling atColombo and Cairo, due to headwinds of 20 kt all along route. Perth-Colombo : Distance, 3,420 n.m.; air-speed, 60 kt; ground-speed, 40 kt; flight time, 85 hr; endurance, 96 hr (at 60 kt); payload, 50 tons. Colombo-Cairo : Distance, 3,100 n.m.; air-speed, 60 kt; ground- speed, 40 kt; flight time, 77J hr; endurance, 96 hr (at 60 kt);payload 50 tons. Cairo-London (via Malta, Ebnas, Toulouse, Bordeaux, Rennes,Havre, Dover): Distance, Cairo-London, 2,200 n.m.; air-speed 80 kt; ground speed, 60 kt; flight time, 36$ hr; endurance, 39J hr(at 80 kt); payload, 50 tons. Elapsed time (with 6 hr for inter-moorings), 205 hr. CASE C. Eastbound, stopping at Cairo and Colombo. Height5,000ft. Wind component + 20 kt. London-Cairo (2,200 n.m.); air-speed, 100 kt; ground-speed,120 kt; flight time, 18 hr, 18 min; endurance, 20 hr; payload 50 tons.Cairo-Colombo (3,100 n.m.); air-speed, 80 kt; ground-speed, 100 kt; flight time, 31 hr; endurance, 39$ hr; payload, 50 tons. Colombo-Perth (this stage-length to be flown at 1,000ft, due toextra payload at Colombo): Distance, 3,420 n.m.; air-speed, 70 kt; ground-speed, 80 kt; flight time, 424 hr; endurance, 46 hr; pay-load 110 tons.Total elapsed time (with 6 hr for inter-moorings), 98Ihr. Stage 4 (Public Transport Schedules):—An example of the flexibility of the dirigible over trans-oceanic stages can be seen when payload is doubled on the Colombo-Perth sector, where no topographical hazards are present. The resulting public-transport schedules represent those ex- pected of a modern dirigible and in no way are they optimistic. The payload is always 50 tons except where stated otherwise. London Cairo Cairo Colombo Colombo Perth Perth Colombo Colombo Cairo Cairo London Perth Aden Aden London London Aden Aden Perth (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) (dep.) (arr.) G.M.T. 0600 0200 0500 1200 0300 2200 0700 0400 0700 1300 1600 0500 0100 0900 1200 1600 0600 1800 2100 0300 Localtime 0600 0400 0700 1730 0830 0600 1500 0930 1230 1500 1800 0500 0900 1200 1500 1600 0600 2100 2400 1100 Localdate Mon. Tues. Tues. Wed. Wed. Thur. Thur. Fri. Fri. Sat.' Sat. Sun. Thur. "1110 tons payload on this Sat. /Sector (Mon., Sun. Tues.Tues. Fri.Fri. Sun. Mon. Thur. Thur. Sun. Sun. Wed. Wed. Sat. Tues. Thur. Thur. Sun.Sun. Tues. Wed. Sat. Sat. Tuet. Tues. Fri. Frt. Mon Wed.) Thur. Sat.Sat. Tus.Tues. Thur. Stage 5 (Statistical Summary):—Assuming 100 passengers per ship; frequency of three ships each way per week; fleet miles travelled per week, 52,200;fleet miles travelled per annum, 2,714,400; payload, 50 tons (available):— Capacity ton-mile per annumAvailable seat-miles per annum Revenue ton-miles per annum (60 per cent bookings)Revenue seat-miles per annum (60 per cent bookings)Revenue at id 'passenger-mile/annum (60 per cent bookings)Revenue at is 4d/ton-mile/annum (60 per cent bookings) 135,720,000271,440,000 81,432,000 162,864,000 £ 678,600 £ 5,428,800 Total Revenue £ 6,107,400 Fares £ s Return fare (based on above costing) 72 10 Single fare 3$ 5 These fares would be affected by catering charges and other expenses not allowed for in purely operational calcula- tions; however, the prices compare well with all other forms of transport to Australia. The schedule is generally "slow" to allow for the possibility of headwinds persisting over the 8,700 miles of route all the year round. Such conditions are unlikely, and some fast easterly trips should be possible. As a final example, on a flight at 10,000ft with a wind component of + 25 kt, the trip to Perth would be as follows : Payload, 50 tons; air-speed, 40 kt; ground-speed, 65 kt; flight time, 134 hr. Schedule at 40 kt:— London depart 0900 G.M.T. Monday Perth arrive 2300 G.M.T. Saturday (0700 Sunday, local). Schedule at 50 kt (116 hours) :— London depart 0900 G.M.T. Monday Perth arrive 0500 G.M.T. Saturday (1300 Saturday, local).
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