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Aviation History
2001
2001 - 2124.PDF
PARIS 2001 posed for potential CF6 upgrade packages. Although details remain sketchy, Boeing's three main studies include: the sonic cruiser, a high subsonic transport capable of Mach 0.95 to 0.98; a conven tional 200-250-seat replacement for the 767; and a more unusual transonic trans port aimed at a Mach 1.2 cruise speed. With the higher compression ratio core capability for higher thrust requirements in mind, P&W executive vice president Bob Leduc says one study option is "an advanced turbofan, which would be a brand new centreline engine. There is a concept we are also pursuing that we think is novel and may have an application on a higher Mach number aircraft." An initial study is also being proposed which is a rel atively simple derivative engine based around the core of the PW4098 developed for the 777-300. R-R is again relying strongly on its well-honed three-shaft architecture - but with some major innovations, hints Phil Hopton, R-R's director of Boeing pro grammes. The three main studies include a "777-based offering in Trent 800 style which doesn't quite do it in terms of thrust", a more advanced concept aimed at an entry-into-service around 2008 and what Hopton describes as "the ultimate sort of engine we could do". Size conundrum Like the others, R-R faces the conundrum of how to adequately size the engine to meet high take-off thrust without making it too large for the relatively high cruise thrust requirement. At the same time, it must also come up with a concept that allows the same engine to perform as close as it can to a low bypass ratio turbojet in cruise, and yet transform to a Stage 4 capa ble high bypass ratio turbofan for take-off and landing. "The big issue really is instal lation," says Hopton, who adds that the large diameter of the 777-style engines and the large high Mach drag these could cre ate are "major issues". At high Mach cruise speeds the engines would be "drinking from a fire hose", he adds. One of the cleverest and most critical design aspects of the sonic cruiser is the semi-recessed engine installation, and the long duct inlet that feeds it. The resulting installation is thought to borrow design features taken from an amalgam of Boeing combat aircraft including the F/A-18E/F, F-22 and X-32 Joint Strike Fighter demon strator. The long duct provides a mecha nism for controlling the flow to the engine, and also hides the fan face. In a military guise this provides low-observabil ity but, in sonic cruiser mode, it cuts down fan noise making it "extremely quiet", says Mike Bair. The integrated engine installa tion and nacelle would also be extended aft to allow the fan and core exhaust to be mixed before exiting, further reducing engine noise. R-R says it is also looking at blow-in and blow-out doors to help control inlet flow at high Mach speeds, and is exploring "more novel ideas like a two-stage fan or even a tandem fan", says Hopton who adds that these are among a "whole host of possibili ties". To tailor the engine for higher speeds, R-R is studying variable area noz zles to help optimise the engine cycle for best cruise performance. It also plans stud ies involving advanced technology being developed for the affordable near term low emissions (ANTLE) engine project. Launched by the European Commission in March 2000 under the auspices of the Hispano-Suiza, Howmet, TRW Lucas Aerospace, Calidus and Spain's INTA Institute. Techspace Aero and Volvo Aero are also involved as are the universities of Florence, Italy, and Lulea, Sweden. Engine exclusivity Overall targets include cuts in carbon diox ide emissions of at least 10% and in nitrous oxide of 60%, by 2008. The sonic cruiser, or whatever newl platform emerges from Boeing's studies, will create an interesting new dynamic in the tightly contested engine market. There have been no hint of demands for exclusivity on any side, though the recent experience of the 777-200LR and -300ER is bound to haunt both P&W and R-R as they make their pitches to Boeing. Efficient and Environmentally Friendly Aero Engine project, the ANTLE engine will be based on a Trent 500. The advanced version will incorporate a new HPC plus intermediate and low pres sure turbines, a low cost turbine rear frame, revised lubrication system and distributed engine controls. The engine will also use a new HP turbine and a dual annular combustor under development at R-R. "We will run a demonstrator engine based on the Trent 500 in 2003, so the timing is about right," says Hopton. Under the ANTLE arrangement, R-R Deutschland is responsible for the HPC, FiatAvio will develop the intermediate pres sure compressor, and Industria de Turbo Propulsores of Spain the low pressure tur bine. Other contributors include Eldim, One of As it stands, the impact of exclusivity on P&W's the longer range 777 models has been offerings dramatic for GE. Without this business, GE will be has 31% of the 777-200/300 market with based around 320 engines delivered or on order, on the compared to a similar number for P&W. PW4098 R-R holds a 38% of the standard 777 mar- core ket, and has almost 390 engines ordered or delivered. GE's business on the former 777X models, accounts for a further 98 engines, or 100% of the long-range market. Perhaps the most important point about the 777 market, from the engine maker's perspective, is its relatively restricted size - just over 1,120 engines so far, not includ ing spares. Although this will undoubtedly grow as the 777 matures, the prospect of another market outlet for the same genera tion of engines is a welcome prospect. • 108 12-18 JUNE 2001 FLIGHT INTERNATIONAL www.flightinternational.com
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