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Aviation History
1955
1955 - 0881.PDF
3000 :20OO 1000 R.D R.I 0.1 ,/] Q.4 V a.;M J R.Da.7 ur R.I 5C a rfr5/' HI > Ste s( »)- I I ^Stoq. 1k.5V 2 D) 7 CENTAURUS FrstCommerciol Services r Delivery of First Servioe Aircraft T.. i.. i..... i............ K . i i , .1 195O 1955 I960 Fig. 4. Increase in power of the Rolls- Royce Dart turboprop. ^ 12 3 4 ••••-•-•• .YEARS. Fig. 5. Increases in engine overhaul life from beginning of airline seryice. 1953 1954 1955 Fig. 6. Durability of power-unit compo- nents: number of defective items changed. IAn K \ XCFNTAURU1; DART I i i I i i I i i I i i I i i I i i \ i i i 1953 1954 1955 Fig. 7. Power-unit reliability in the air: number of defects reported in flight logs. 06 0-7 0-8 0-9 AIR MILES PER GALLON 1-0 Fig. 8. Air miles per gallon achieved by B.E.A. Viscounts. Holding a.m.p.g. (140 kt) are similar. 500 V500 1300 SECTOR DISTANCE (st mil«$) Fig. 9. Comparison of aircraft cost per seat- mile (U.S.A. cost structure) on short hauls. 87924 June 1955 During the first 200,000 engine hours of Dart flying in B.E.A.'sViscount aircraft, between January 1953 and May 1955, occasions on which airscrews have_ been feathered on account of failures ofcomponents of the engine itself totalled one feathering, for all causes, in every 4,550 engine hours flown. This compares withone feathering for every 2,860 engine hours flown with the Centaurus piston-engine, which is comparable with the Dart as anew engine in civil airline and B.E.A. service. Details of causes of Dart featherings during the first 200,000turboprop engine hours of B.E.A. flying were then set out by the lecturer in the following form:— Number Percentage EngineCause of Feathering " V .- of of total Hours per ' occasions featherings feathering(1) Instruments and electrics 54 (2) Reduction gear (torquemeter) (engine) 17 (3) Fuel system(4) Miscellaneous mechanical defects (engine)(5) Turbine blades and bearings (engine) (6) Accessories—Fuel pump etc. (engine)(7) Combustion system (engine) 541 13 11 7 5 4 49 15 12 10 6 4 4 3,70511,760 15,390 18,200 28,60040,000 50,000 111 100 1,800Total featherings in 200,000engine hours. Out of 111 featherings [continued the lecturer] only 44, or 40 per cent, were caused by failure of the engine itself—averaging onefeathering in every 4,550 engine hours. Dart featherings in the air which necessitated a subsequentengine removal have amounted to 31 altogether in 200,000 engine hours—an average of one for each 6,500 hours since the start ofoperations. This compares with one for each 11,000 hours for the Centaurus—which is a very good figure indeed. In all, 137 time-expired Dart engines have been removed at amean time of 618 hours between overhaul while lives have been built up. In addition there have been 142 premature removalsfor various causes; such removals are now becoming progressively less. Incidentally, Dart engine changes can be performed com-fortably in two hours. B.E.A.'s Darts are now running at 1,050 hours between over-haul, with flame-tube changes at 750 hours. This latter figure is on the point of being increased to 1,050 hours. Achieved hourssince the start are, naturally, somewhat less than this but, there is plenty of evidence to lead us to believe that the achieved hoursbetween overhaul will increase substantially during the next years. We are setting as our immediate target at least 1,250 hoursbetween overhaul for the complete engine including the flame- tubes. This is part of the longer-term target of at least 2,000hours for the cold part of the engine. Flying Experience. Looked at now from the pilot's point of TABLE IV: ROLLS-ROYCE DART TURBOPROP ENGINES 1 2 3 4 5 6 78 9 Engine designation M.o.S.designation (powerrating) R.Da.1 R.Da.2 R.Da.3 R.Da.4 R.Da.5 R.Da.6 R.Da.6 R.Da.7 Stage 1 R.Da.7 Stage 2 MarkNo. (a) 504 (b) 505 (c) 506 502 510 511 Reductiongear ratio 0.091 0.091 0.091 0.106 0.106 0.106 -1.106 0.093 0.086 Take-off performanceI.S.A.C. Power s.h.p.t thrust 1,000+325 Ib 600+ 1,400+365 I b 1,400+365 Ib 1,400+365 Ib 1,250+340 Ib 1,640+365 Ib 1,600+370 Ib 1,600+370 Ib 1,950+430 Ib 2,100+435 Ib e.h.p. 1,125 1,547 1,547 1,547 1,380 1,780 1,780 1,780 2,115 2,268 r.p.m. 14,300 14,500 14,500 14,500 14,500 14,500 14,500 14,500 15,000 15,000 Max. cruising performance20,000ft. 250 knots I.S.A.C. Power s.h.p., thrust 530+55 Ib 400+ 858+70 Ib 948+70 Ib 750+65 Ib 990+70 Ib 967+70 Ib 967+70 Ib1,160+78 Ib e.h.p. 642 912 1,002 800 1,044 1,021 1,021 1,220 r.p.m. 12,900 13,800 13,800 14,000 13,800 13,800 13,800 14,000 14,000 Specific fuel con. Ib'hr'b.h.p. 0.8 0.722 0.67 0.76 0.658 0.662 0.662 0.583 Date Oct. 1947 to end 1948 Pre-production Production, 1952 Production, 1955 1950 Projected, July 1953 Production, June 1955 June 1955 Dec. 1956 Aircraft in whichinstalled Flown in Lancaster nose. Installation trials in Wellington Not flown Dart-Dakota Viscount V.700 series Viscount V.700 series Viscount V.630 prototype Projected for V.801 Viscount Major V.802 Fokker Friendship V.800 development
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