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Aviation History
1963
1963 - 0089.PDF
/ LIGHT International, 17 January 1963 80-81 \VON Best overhaul life with this renowned turbojet has been •schieved by BOAC's Comet 4 engines, which are now running to : .500hr and trialling to 3,800hr. Though never exceeding 0.5, unscheduled-removal rate rose during the first two years. It is now , oming down to a level approaching 0.3, and the rate of increase in overhaul life has been matched only by the Conway. High- pressure turbine blades have been run as high as 8,000hr, nozzle iUiide vanes to 8,500 and flame tubes to 7,000. CONWAY Everyone knows that the Dart is a reliable engine, and ^ome would say it is the epitome of reliability; yet the Conway is better. There are indeed some people in Rolls-Royce who say flatly: "The Conway is the best engine we have ever built." The rate of increase in overhaul life, now trialling to 3,100hr land approved at 4,800hr in TCA service, with an intermediate check), has consistently been higher than that of any other turbine aero engine in the world. At just over 0.1 per l,000hr, the unsched uled-removal rate is the best achieved by any engine in history, und more than twice as good as the Dart after ten years. In intensive service in Conway 12 form, the future of this engine depends on the market for the higher-powered Conway 42 and 43 (VC10 and Super VC10) developments and their applicability to the longer-range DC-8s and 707s. So far, developments of these aircraft (the 707-320B and 320C and the DC-8-50 and DC-8F) have been matched successfully to the Pratt & Whitney JT3D uirbofan. The Conway 42 has not yet secured a foothold in the market for advanced 707s and DC-8s, the main obstacle being the number of Conway-powered aircraft that would have to be ordered to cover the certification costs. Boeing spent about two years developing the 320B, and although the cost of incorporating the revised wing with high-lift devices has to a large extent been spread over orders received for P&W-powered aircraft, the projected Conway-powered 707-420B would still require about a dozen aircraft to be ordered for the cost to be justified. As is well known, BO AC have indicated a need for 707-420Bs if the Super VC10 proves unable to fly London - Los Angeles nonstop, as it was never intended to do. An order for a dozen 707-420Bs from BOAC would give the Conway 42 the break it needs; but there are political as well as financial difficulties. The question of re-engining some of BOAC's existing 707-420s with Conway 42s has been considered, but has now been rejected mainly because the full benefits of the higher power and lower specific consumption would not be fully exploited without the airframe changes. Technically and commercially, the Boeing 707-420B and the -320B would be just about identical. The fiat-rated Conway 42 (20,3701b guaranteed minimum static rating ISA, compared with 18,0001b for the latest JT3D-3) has the edge on "hot and high'" performance, being able to hold its power up to temperatures of about 100F, which are certainly well within the conditions that BOAC are likely to encounter. Test-bed specific fuel consumption of the Conway 42 is about 8 per cent higher than that of the JT3D, but air mileage per pound of fuel is within a fraction of one per cent due to the higher drag of the turbofan nacelle. Meanwhile, Rolls-Royce are offering their present customers a further bonus with the present RCo.12. This engine was uprated from 16,5001b to a minimum of 17,5001b before it entered service, and by the incorporation of minor mechanical changes can now be given a further 6001b of thrust coupled with ?. reduction of two per The main throttle control of a Conway 508 from a 707-437 is the subject of this discussion between a company representative and an engineer of Air-India International at Bombay cent in s.f.c. These improvements are gained with no penalty in weight or reliability, and will be used principally to improve hot- and-high airfield performance—the engine being flat-rated at 17,5001b up to a high ambient temperature—as well as range. Alitalia have specified the improved engine in their repeat order for two DC-8-40s, and will probably standardize on it throughout their DC-8 fleet. Conway 12 business to date has brought in nearly £29m, with over £4m of further orders on the books. Spares consumption from 1960 to 1973 is likely to exceed £31m; and sales of Boeing pods (which Rolls-Royce fabricate) has generated a further £3m or £4m. So, all in all, the Conway 12 is likely to generate business approaching £70m. To this must be added the £80m expected from Conway 42s and 43s and spares for the VC10 and Super VC10 over the next ten years. SPEY A rough assessment of the future world market for civil turbine engines suggests that half of it could be a Spey market. Orders for long-range and medium long-range jets, like the 707. DC-8 and VC10 families, are growing all the time and will continue to do so—but not at the same rate as the markets for the short, medium and short-range jets, such as the BAC One-Eleven, D.H. 121 Trident and Boeing 727—and the F.28 and Douglas 2086 if they are launched. There are basically five members of the family, ranging in thrust from the 8,6501b of the Spey Junior to the 11,4001b of the Spey 25. As recently reported in these pages, the Government has decided to put money into the development of advanced Speys. Rolls- Royce has so far spent some £9m on Spey development and the Government has contributed £3m. Sharing of costs on later engines will assist considerably in the development of the Spey 2, 2W (water injection) and 25. The family, which includes a military version for the Buccaneer, is shown in the table below. The Spey could repeat the story of the Dart (even the Mark numbers are starting out the same). On its success depends, to a great degree, the future of Rolls-Royce. Left, current members of the Spey family ofturbofans (by-pass wrbojets). Right, the remarkable record of the civil Conway RCo.12: total flight time, time between overhaul and the three-monthly average for the basic unscheduled-removal rate Aircraft Trident Trident Trident BAC One-Eleven BAC One-Eleven BAC One-Eleven Blackburn Buccaneer S.2 Trident BAC One-Eleven Project number RB 163-1 -2 -2W -1 -2 -2W RB.I68 RB. 163-25 -25 Mark No 505-5 506-5 506-5W 505-14 506-14 506-I4W — 510-5 510-14 Rating RSp.l RSp.3 RSp.3 RSp.l RSp.3 RSp.3 — RSp.4 RSp.4 Take-off thrust 9,8501b 4,468kg 10,4101b 4,722kg 10.4101b 4,722kg 10,0001b 4,536kg 10,4101b 4,722kg 10,4101b 4,722kg — 11,0001b* 4,990kg 11,0001b* 4,990 kg Maximum continuous thrust 9,4501b 4,2B6kg 9,9901b 4,531kg 9,9901b 4,531kg 9,4501b 4,286kg 9,9901b 4,531kg 9,9901b 4,531kg — I0,540lb * 4,781kg I0,540lb* 4,781kg Maximum basic dry weight 2,2001b 998kg 2,2421b 1.017kg 2,2731b 1,031 kg 2,2151b 1,005kg 2.2571b 1,024kg 2,2881b 1.038kg — 2.3121b 1,049kg 2,3271b 1,055kg Final ratings: take-off thrust, 11,4001b (5.171 kg); max continuous, I0,940lb (4,962kg). TO 4,800 WITH PART- LIFE INSPECTION 3.000 TBO(hr) 2,000 1,000 0-5- go*. <0-3- gO-2- w • rrS^ _—--^ r~ X X TOTAL S~ CONWA S TIME >\^ REMOVALS I Y YEARS FROM START
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