FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1983
1983 - 0984.PDF
PARIS SPECIAL by a three-stage low-pressure turbine, with very similar aerodynamics to that of the -535 LP turbine. Tests of the low-emissions can-annular combustion chamber have shown that it is capable of meeting the pollutant and smoke regulations which are in the pipe line, and of improving engine starting performance. Its secret lies in a new curved-vane aerodynamic swirler, to better mix the incoming fuel and air, and in Rolls-Royce's transpiration-cooled "Transply" combustor liner. This enables the mixture to be burnt at higher temperatures, with corresponding reduc tions in emissions. Acoustic liners are used in the intake and exhaust duct, and like the -535E4, a "common nozzle" internal exhaust mixer is introduced. This has the effect of improving mixer efficiency, and hence propulsive efficiency, as well as reducing noise. Nacelles for the Gulfstream IV- mounted Tays are currently the subject of a contract tender, put out by Gulfstream to a number of companies. The likelihood is that the design will be such that it suits the Fokker F.28 installation as well, if, of course, Fokker goes ahead with the Tay- powered F.28. Rolls-Royce funding The Tay has to-date been funded entirely by Rolls-Royce. While the company declines to reveal what the cost to certification will be, it says that even if the Gulfstream order is the only one that materialises, the project will have been economically viable. This clearly owes much to the heavy reliance on research and development already applied to existing engines. The Tay should mature much faster than a new engine on account of its proven core. The aim, says R-R, is to at least match the maintenance costs of the existing Spey MK555, and Pratt & Whitney JT8D-15 and -17. Rolls-Royce reckons that about 2,300hr of development testing lies ahead before the Tay is certificated in mid-1986. The first engine should run in August 1984. TAYvs Thrust (lb) Overall pressure-ratio Bypass-ratio Turbine entry temperature (K) Overall length (in) Fan diameter (in) SPEY Tay 13,550 15-5:1 3:1 1,300 101 44 Spey 9,900 15.4:1 1:1 1,300 96.7 32.5 Notes (a) Values are for sea level and ISA (b) Spey figures are for powers the latest F.28 the 555-15P, which Doing battle with 25-tonners The three major aero-engine manu facturers are all now offering turbofans for bigger versions of the current twin-engined widebodies, and growth Boeing 747s. A market for at least 1,000 such aircraft up to the end of the century has been perceived. Latest to join the club was Rolls-Royce, which revealed in April its intention to offer the 59,0001b RB.211-600. Subject to a formal go-ahead, this would be certifi cated in 1986. This engine is about 10 per cent more powerful than the RB.211-524D, certificated in March 1981. The contenders already in the field are General Electric's CF6-80C2, which ran last year at 62,0001b, and is on show at Paris, and the Pratt & Whitney PW4000, a 56,000-58,0001b thrust development version of the new, medium-thrust PW2037. General Electric has said that it will achieve certification of the CF6-80C2 in 1985—a year earlier than either Pratt & Whitney or Rolls-Royce. Whether this proves significant or not remains to be seen, since there is still no appreciable demand for the aircraft which will need these ultra high thrust engines. The Airbus A300-600, Boeing 767-300, Boeing 747-300, and the McDonnell Douglas MD-100 are all possible applications, while in the longer term, the 400-seat Airbus TA9 could materialise. The signs are, however, that the recession in the airline industry may be past its worst, and that orders could start building up by mid-decade. General Electric likes to call the CF6-80C a new engine, although it is derived from the CF6-50 with which the company carved its niche in the commer cial turbofan market. This is largely because the -80C has received so much technology feed-in from GE's Nasa- sponsored Energy Efficient Engine (E3) programme. This has been running for some years, culminating in a 50hr test run of the complete engine in April at its Peebles outdoor test site. Input from E3 has resulted in a more efficient high-pressure turbine, which runs some 100° F cooler than that of the CF6-50, while blade-to-casing control is improved and exhaust emissions reduced. The CF6-80C2 is very similar to the -80As that power the Airbus A310 and Boeing 767, but has a bigger fan to achieve the extra thrust—and another low pressure turbine stage to drive it. Nasa's goal for the E3 programme was for a 12 per cent reduction in fuel burn over that of the baseline CF6-50. GE claims that the -80C2 achieves an 11 per cent saving. Nasa's E3 programe was taken up by Pratt & Whitney too, much of the learning being passed into the PW2037, and hence the PW4000. Pratt & Whitney talks about the PW4000 as a "radically new engine designed to save airlines hundreds of millions of dollars per year in fuel and maintenance costs". Comparison with the JT9D-7R4, which it will eventually replace, certainly reveall some interesting changes, most of which relate to the 54 per cent parts reduction relative to the earlier engine] P&W says that fuel burn will be improved by about 7 per cent over the -7R4, whichj itself benefits from recent advances, such as supervisory digital electronic fuel- control, and single crystal high-pressure turbine blades. No sooner had Pratt & Whitney' announced the PW4000 than Genera Electric replied with the message that it was "hardly a leap forward". Its owri CF6-80C2, it said, would be ready a year earlier, and offer similar improvements in fuel burn. So, battle was effectively joined by two of the "big three". Rolls-Royce's? comment at the time was that it still sa%« no demand for aircraft needing the highel thrust engines, (although it had demon strator programmes for such a powe>j plant, which would draw heavily on iS RB.211-535E4 technology). "There will bj no announcement until an application ij seen," it said. Plans for the RB.211-60 have now been revealed. The aircraft it i aimed at are clear, and Rolls-Royce vie with its US brethren for a slice of t^ action. The RB.211-600 is called an "advancS new version of the RB.211 series". 1*. technology imput, while not Nas sponsored, results nevertheless fro: considerable research and developrru^ over the last few years. It will be the onlj high-thrust turbofan in service wit' wide-chord, snubberless fan, the fi version of which is due to start work ol the -535E4 at the end of next yei Although used first on the smaller engiji full-size snubberless fans have b running on the big RB.211s for s<* years. The -535E4 was simply the e:_^: which pushed the introduction of the fi to commercial service. Fuel-burn of the -600 will, says R-ft, to about 8 per cent better than that of thi -525D4. Some of this is due to the fan, bli there are other improvements, includi.to: "end bend" compressor blades in botl intermediate and high-pressur compressors, the blades incorporating ne\ supercritical airfoils; "three dimensional- single crystal HP and IP turbine blaigf and nozzle guide vanes, and new, IS emission, transpiration-cooled combusi cans. The 535E4-type common exhau^ nozzle will not be incorporated, since \m applies specifically to the medium thri,i< engine. • If the market shapes up to the antici pated 1,000-plus aircraft, there should B room for all three manufacturers to sell i worthwhile number of engines. Th' question will be, "who powers what? Perhaps Rolls-Royce could after all fin itself powering Boeing 767s, DC- 10s—c even Airbuses. n 1564 FLIGHT International, 28 May .1
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
