General Electric has great plans for the GE90 but its near-term future is pinned on the longer-range 777s
For all engine makers, the development game is a long one - yet some play a hand that stakes much on a single core concept and the family of engines that descends from it. At General Electric Aircraft Engines much of the future is staked on the GE90. Some worry that this also makes it heavily dependent on just one type of aircraft: longer-range Boeing 777s. But the manufacturer claims a wider role for the GE90 as the foundation of its powerplants over the next 10 to 15 years.
The engine's core will feature in the GP7200 that GE is developing for the Airbus A380 in conjunction with Pratt & Whitney (P&W). It will also furnish the basis of what GE calls the Gen X engine intended to power the Boeing Sonic Cruiser. Technologies developed in the GE90 programme will also apply to future traditional commercial aircraft, including regionals and narrowbodies.
GE's general manager for advanced engineering, Mike Benzakein, says: "The engine core can never remain static and must evolve though the years." It is probably the most difficult and expensive part of a powerplant to develop, he adds, explaining that cost efficiency dictates "we keep the same core design and use our field experience to improve the product." For example, he says, field experience helped in detecting wear on bushings: "Something like this is realised more in the field than in testing, because the customer cycles the engine more than we could." In the light of the customer's experience in this case, the next variant's bushing would be made out of different materials.
Here, GE is building on its past experience with the CFM family, the smaller powerplant it builds with France's Snecma. That was an evolution that became a completely different machine, Benzakein says, recalling that the core of the CFM family, which powers the new generation Boeing 737 family, was a military model, the F101. It has been essential to all CFMs since 1974. Benzakein says: "Over those years, we changed almost every part - but the architecture was right." Eventually, GE will try to combine the key parameters of the single-stage turbine architectures of the CFM56 and its own CF34-10, and end up with a reduced number of stages, very high-pressure ratio and a single-stage turbine. This would require less maintenance and be more fuel-efficient.
Of the GE90, he says: "Today's compressor is different from five years ago. One change made about a year and a half ago gave us 1.5% better specific fuel consumption. Using new turbine material for disks and rotors let us go to higher temperatures." However, with the GE90, the developments are not all in physical materials. Information technology has as much of a role. "Computational fluid dynamics now lets more complicated calculations be made than just three years ago. We can now simulate multi-staging effects. That way, when we wanted more thrust, we could keep the core design alive." The GE90 went from 76,000lb of thrust (338kN) to 94,000lb, and eventually to the record thrust level of which it is now capable.
Last year, GE began full engine testing of the GE90-115B in southern Ohio, not far from its base near Cincinnati. The engine established a new record for jet engines, reaching 120,316lb thrust on 19 November, and since. That beat a record of around 110,000lb set by a Rolls-Royce (R-R) Trent.
Correct architecture
None of this could be done if the basic core architecture was not right. When GE made the decision in the late 1980s to launch the GE90, it could have stayed with its time-tested CF6. Instead, GE says: "We decided to start from scratch and so we evolved a brand new machine. We believe it is the right architecture for long-range applications where fuel-burn is so important."
In its early years, though, the engine suffered widely reported and well-known teething troubles, and the company's ambitious plan for the -90 series ran into some highly public problems. One observer, Teal Group analyst Richard Aboulafia, says that the GE90 illustrates the old saying: 'Out of pain, comes a learning experience.' GE has obtained its market leadership in spite of the -90, not because of it," he adds.
If the GE90's applications are a technical success, its commercial feasibility stems largely from a business arrangement. Its exclusivity pact with Boeing for longer range and heavier versions of the 777 was made in summer of 1999, when the aircraft-builder selected GE over P&W and R-R. The GE90-115B that will be used on these models could bring in as much as $15 billion for GE if Boeing sells 500 of the long-range 777s. The exclusivity deal was portrayed as a bowing to economy reality: it could not be certain that the long-range 777 would sell well enough to justify a competition among the three traditional rivals, says Aboulafia. In any case, Boeing did well from its exclusivity agreement with CFM to power the new generation 737 family.
According to Aboulafia: "The sole-source selection of GE may have looked like an act of desperation, but there is a method to the perceived madness. The GE90 has a huge core and can be grown. It could even be expanded to create an ideal 747-400 replacement, a hypothetical aircraft I call a 777-400, even though Boeing denies it plans such a 777. Some airlines probably wanted a Trent-powered long-range 777, and Boeing may have lost orders due to that, but the GE90's growth potential may well be enough to compensate for this."
R-R still argues that it would have preferred the market to have been offered a choice, because the Trent 800 is "a good technical match for that aircraft".
Although the Trent 800 is not available on longer range 777s, R-R adds that it is still the market leader on the rest of the 777 fleet, with a 44% market share.". Some prominent Asian airlines, the region for which the 777 long-range family was created, have a long relationship with R-R which may be difficult to challenge.
R-R also notes that the Airbus A340 growth programme (the -500 and -600) directly competes with the Longer Range 777, and that the Trent 500 is the only engine available for this programme.
The other rival is philosophical about the GE90's lock on the bigger 777s and diplomatic about its future applications. P&W says: "We all presented very aggressive proposals for the exclusivity pact. You can't blame GE for what they did." P&W says it had adopted a growth strategy for its PW4000 family earlier. PW4000s are on around 125 777s. Teal Group predicts that by 2010, GE90s will be on 356 of the 777s that it thinks will have been produced by then, with Pratt 4000s on 258 more, and Trents on 317 variants of the 777.
GE acknowledges the market for the Boeing 777-200LR and -300ER is slowing as the attacks of 11 September exacerbated and extended the industry downturn. Late last year, orders for those aircraft types stood at 52, of which most were for the 777-300ER. An order booked on 31 December for five more 777-300s from an unidentified customer does not specify variants, says Boeing's Tom Ryan. Boeing has put on the back burner its support for development of the 777-200LR.
Confidence
But GE remains confident the market will recover, and insists it will forge ahead with the -115B programme, not just because of its commitment to the longer-range 777s, but also because it sees the very high-pressure ratio technology of this engine being applicable to future applications.
Not all GE90 applications will necessarily require a bigger machine, however. Benzakein says the core will offer the base needed to develop an engine for the proposed Boeing Sonic Cruiser. An all-new engine design will not be necessary for this near-supersonic aircraft, he adds, based on what we now know.
GE believes the early model of the Sonic Cruiser will be a 250-passenger airliner that needs an integrated engine in the 90,000lb-thrust range. This early model is expected to offer a range of 2,700km-3,250km) (5,000-6,000nm), and so would not compete with the 777-200LR's 4,750km-range capabilities.
Although the crisis may have slowed some airliner development, it is widely seen as providing a boost for Boeing's Sonic Cruiser strategy of fragmentation, one in which the 777 is also a winner.
So now the GE90 strategy is looking far-sighted, according to Paul Nisbet of JSA Research. He says of GE: "They were looking far ahead. Engine makers have to."
Source: Airline Business
