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Aviation History
1961
1961 - 0659.PDF
rFL3HT, 18 May 1961 • r.:"tf ••>TV"~-ti^r<f-fR^^ 669 bv "-Sin- Tne increased mass flow gives 1,0001b more thrust, andthe ncorporation of detail refinements confers an improvement in ctx ?ng consumption. The resulting engine is designated ConwayRC 15B. Delivery of these engines is now in progress for the "S ier DC-8s" of Canadian Pacific, for scheduled service at the ec ,»f the year. CPALare to convert their RCo. 12-powered aircraft(ti,: rirst three of their fleet) to RCo.l5B power at a later date. : >st run of an RCo.l5B took place early in 1960, and manufac-tu •- of engines to the production standard began more than a year a,., Rolls-Royce also offer an engine designated RCo.15, incor-prating only the revised zero-stage and thus giving the 18,0001b gi ranteed minimum rating, but not enjoying the improved con-si nption resulting from the detail modifications to the gas path. A aough both the RCo.15 and RCo.l5B require a new nose cowl,th ir installation is in other respects identical to that of the RCo.12, ar;; initial overhaul life is not expected to be substantially less thanthe corresponding figure for the RCo.12. Next step in the development of the Conway is a larger one. By1959 it was clear to Rolls-Royce that the by-pass ratio of the Con- way was lower than the optimum, and it also seemed likely that a20.0001b-thrust engine would before long be asked for by transport manufacturers. Two courses appeared to be open to the Derbydesigners: either a new 20,0001b engine could be drawn on a clean sheet of paper, or a new 1-p line could be designed to fit around theexisting h-p assembly. In the event, the latter course was adopted. The h-p system is notoriously the difficult and expensive part of anengine, and its retention in the new Conway was considered a very great advantage in reducing development difficulties and in ensuringa rapid build-up to a satisfactory overhaul life. The VC10 Engine Designation of the new engine is Conway RCo.42. Its h-p com-pressor, combustion system and h-p turbine are basically identical with those of the RCo. 15B, so that by the time the engine entersservice these critical parts will have exceeded 2,000,000hr in airline service, and maximum lives of individual hot parts should be of theorder of 6,000hr. Around this nucleus Rolls-Royce have matched a new 1-p system consisting of a compressor of increased capacity anda rebladed turbine, giving a by-pass ratio of 0.6. Rig-testing of the new 1-p assembly started early in 1960, and the first RCo.42/1engine ran for the first time in March 1961. This " 1 ^-generation" powerplant is now entering production for the Vickers-ArmstrongsVCI0. 18 of which have so far been ordered. Deliveries to Wey- bridge will begin for certification testing in September, and quantitydeliveries will be made throughout next year. In the RCo.42/2, detail refinements could effect an improve-ment in specific consumption, but it is unlikely that this unit will be built. The same improvements are incorporated in the RCo.42/3,in which a substantial increase in thrust is gained by clearing the engine to operate at increased r.p.m. This method raises both themass flow and pressure ratio, but it demands engineering changes in the casings, discs and blades. Accordingly, the RCo.42/3 is beingdeveloped to a schedule about a year later than that for the RCo.42/1. The RCo.42/3 is the engine chosen for the first 30 SuperVC10 aircraft for BO AC, and the first powerplants for these aircraft will be delivered towards the end of 1963. Reference to this journal's report of the 1960 SBAC Show indi-cates that at that time Vickers were thinking about stretching the VCI0 still further, to an overall length of 196ft 6in and a grossweight (as a freighter) of 373,0001b. The powerplant specified was the "Conway 7," which we described at the time as an RB.163Spey scaled up to give a thrust of about 24,0001b. In the event, it is now considered unlikely that this "Super-Super VC10" will bebuilt, but basic calculations on the Conway 7 have been com- pleted and such an engine could be produced within three years if afirm requirement were to materialize. DART It is now 15 years since the development of this turbopropbegan, and it was affectionately described as "agricultural machinery" by one of its largest users five years ago. Nevertheless,it is impossible to open a discussion of the Dart with any feelings other than profound respect, for it has proved—and we are speakingstrictly metaphorically—a blazing torch, which has illuminated the way along which all other modern airline engines have followed.Scheduled service began with the Dart 505 (later 506) in the BEA Viscount 701 in April 1953, at an overhaul life of 400hr. Total timein airline service today exceeds 15,000,000hr, and the scheduled overhaul life with most operators is substantially greater than thatof any other powerplant in the world. First operator to exceed 3,000hr was Capital Airlines (now part of United), who run theirDart 510s to 3,100hr. A time of 3,20Ohr was reached by TCA's Dart 506s last March, and in January BEA achieved 2,750hr ontheir powerful Dart RDa.7 Mk 520s (their 510s are on 3,000hr). Overhaul life depends greatly upon the operator. For it to be high,stage-lengths must be long (because this gives the engine an easier life), and utilization must be intensive, so that time-expired enginescan be "pulled'" quickly and in sufficient numbers to prove each new extension of life. The attitude of the airworthiness authority in thecountry concerned also has a bearing on the permitted figure, but in the case of the Dart no authority regards it with suspicion. It isworth noting that over 800 aircraft have been ordered with Dart power, including airliners for 128 civil operators in 37 countries.In 16 of these countries there are located 23 bases at which Darts are regularly overhauled. It is not possible to forecast the ultimate time between over-hauls which the Dart will reach. Already, most operators need pull their engines only once a year, and the matching of very longengine life with the routine maintenance demanded by the airframe in which it is fitted is a problem involving many difficult variables.Nevertheless, operators in general are keen to extend engine over- haul life, and 4,000hr can be predicted with confidence. The com-plete powerplant goes through the same scheduled life, with no more than routine inspection between times. The overall life of the majorindividual parts is in no case less than two engine overhaul periods, and typical figures for the major hot parts for a Dart 510are: flame-tubes and h-p turbine blades, 6,000hr; h-p disc, 9,8OOhr; nozzle-box, 12,000hr. Basic carcase life has not yet been determined, and thelife of the more critical components is being progressively extended by the introduction of improved materials, cooling arrangementsand detail design. Practically all the 3,250 Darts so far manufactured have been tothe RDa.3, RDa.6 and RDa.7 ratings, described in our issues of March 20, 1953 and February 28, 1958. Many marks of RDa.6and RDa.7 remain in full production. All are civil engines, apart from the Mk 21 which powers the Breguet Alize ASW aircraft;rated at 2,020 e.h.p., the Mk 21 matches an RDa.6 compressor with an RDa.7 turbine. From these families has now been evolvedanother military engine, currently in volume production for the Argosy C.ls of RAF Transport Command. Designated RDa.8Mk 101, this engine is essentially an RDa.7 with 65°C increase in flame temperature, and a water/methanol system which boosts, ROLLS-ROYCE AERO ENGINES First run (month and year) Engine designation Type Compressor and turbine stages Max basic dryweight (Ib) Mass flow (Ib/sec) Pressure ratio By-passratio Guaranteedmin ratingIb-thrust] [e.h.p. Typical cruise rating; altitude(U), speed(kt), output (Ib or e.h.p.) and s.f.c. (e.h.p.) NA NA 25.000; 425; 3.400; 0.936 25,000; 425; 4.680; 0.898 NA 35.000; 475; 4.800; 0.900 35,000; 475; 5.200; 0.8*2 35,000; 475; 5,430; 0.840 35.000; 475; 5.570; 0.820 20,000; 300; 955; 0.655 20,000; 300; 985; 0.634 20,000; 300; 1,315; 0.573 20.000; 300: 1.612; 0.556 NA NA NA 36.090; 560; 2,750; 0.777 25,000; 370; 2,685; 0.405 25,000; 370; 3,180; 0.389 30,000: 320; 2,695; 0.391 30.000; 320; 2.786; 0.388 30,000; 320; 2.803; 0.389 30,000; 320; 3,005; 0.383 Max •pp. over- haul life (hr) Nov 51 March 56 June 58 59 Nov 57 June 60 March 61 Nntyetrun July 46 Nov 50 July 56 March 58 J..iy 55 •ov 59 '•-••K 60 "Nl 55 Avon Conway Dart RB.I08 RB. 141/11 RB.I45 Spey I Tyne RA.24R RA.28 RA.29/1 RA.29/6 RB.I46 RCo.12 RCo. I SB RCo42/t RCo.42/3 RDa.3 RDa.6 RDa.7 RDa.10/1 RTy.l RTy. 11 RTy.l 2 RTy .20 RTy.2l RTy .22 TJ* TJ TJ TJ TJ» TF TF TF TF TP TP TP TP TJ TF TJ TF TP TP TP TP TP TP NA 15,2 16,3 17,3 NA 7 + 9, I + 2 7 + 9, i + : + 3 + 9, I -t -T 3 + 9, 1 -i 2, 2 2,2 2, 3 2, 3 8, 2 5 + 11,2+2 NA 4 + 12,2 6 + 9, 6 + 9, 6 + 9, 6 + 9, 6 + 9. 6 + 9, + 2+ 3 + 3+ 3 + 3+ 3 -J- 3 NA 2,869 3,308 3,471 NA 4,544 4,584 5.001 5,100 1,026 1,106 1,207 1,377 262 3.613 NA 2,200 2,275 2,275 2,177 2,205 2,279 2,279 NA NA 173 185 NA 281 295 363 363 20.5 20.5 23.5 27 NA 273 NA 202 46.5 46.5 46.5 46.5 46.5 46.5 NA NA 9.1 10.3 NA 14.1 14.3 14.6 14.6 5.4 5.4 5.6 6.35 NA 16.75 NA 16.75 13.5 13.5 13.5 13.5 13.5 13.5 0.3 0.3 0.6 0.6 0.7 1.02 11,250 (14.430*) 10,150 10,500 12,725 13,230(16,600*) 17.500 18.500 20,250 21.800 1,480 1,660 1,815 3,030t 2,010 15,000 2,750 9.850 4,785 5,325 5,500 5,855 6,180 7,075t NA NA 2.600 1,400 NA 1,600 3.200 3,100 2,750 * With reheat (afterburning); t With water/metranol boost; NA, not available.
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