Rolls-Royce pushes new engine concept for 777X

Washington DC
Source:
This story is sourced from Pro
See more Pro news »

Rolls-Royce has unveiled its all-new RB3025 engine concept for the 777X, responding to the airframer's 2011 request for information issued to itself, GE and Pratt & Whitney for Boeing's conceptual widebody.

"Boeing asked the three engine [manufacturers] what we could do in terms of product for what is now called the 777X, at around the end of this decade," says Rolls Royce vice-president of strategic marketing, Robert Nuttall.

Most observers predicted that GE would retain the exclusivity it currently enjoys with its GE90 which powers the 777-300ER, -200LR and Freighter, on Boeing's next-generation 777, by offering its conceptual GE9X. However, the emergence of additional proposals kicks off what is likely to be a fierce battle to power the 777X-family of aircraft.

Rated at 99,500lbs with a 337cm (132.5in) fan for the baseline 407-seat 777-9X, giving the RB3025 a bypass ratio of 12:1, Rolls touts a "better than 10%" improvement in fuel burn over the incumbent GE90-115B engine and 15% better than its Trent 800 which powers early model 777s.

Rolls says the current concept provides a low specific thrust and "excellent" propulsive efficiency, along with a 62:1 overall pressure ratio, which, if achieved, would be the highest OPR demonstrated in a commercial turbofan engine.

The RB3025 builds on the Trent 1000 and XWB engines, but Nuttall says the concept is built around its Advance3 environmentally friendly engine (EFE) technology development programme, which includes a Trent 1000-derived core, lean-burn combustor, composite fan and advanced materials in the combustor and high pressure elements of the core.

"We're pleased to be dependent on Boeing's decision-making here," says Nuttall of a development schedule. "We're targeting an end of the decade timescale, but that will be entirely down to what Boeing tells us. Then obviously we'll work backwards from that date."

Boeing declines to say whether or not it will offer multiple engine choices for the 777X: "It would have to be a programme before we made a decision like that," it says.

The airframer aims for a late-2012 official launch from the company's board of directors.

The 777-8X concept, a 353-seat stretch of the 777-200ER, would have a thrust requirement of 88,000lb and Nuttall says Rolls aims to have a "single bill of materials" for the RB3025 engines on both the -8X and larger -9X, in which the lower thrust is achieved through a simple engine de-rate.

Nuttall says Rolls will take the next "year or two" of design work with Boeing to optimise the engine around the conceptual aircraft, requiring roughly six years ahead of a service entry to fully develop a new engine.

"The design is already quite comprehensive, but we would flesh that out in more and more detail, getting much more down to component level [design]," says Nuttall of its plans for 2012.

"The design we've got, most people wouldn't be able to tell the difference between [the RB3025] and the finished engine. We've got tremendous amounts of detail that we're sharing with Boeing currently," he adds.

Rolls has historically voiced its opposition to aircraft re-engining programmes, though the company looks to enthusiastically pitch the RB3025 for the re-winged, re-engined 777X, citing the aircraft's new composite wing as a key component for achieving the overall optimisation the engine maker prefers when making such a large-scale investment.

"As far as fuel burn is concerned, the wing on an aircraft is the predominant technology, I think we're quite comfortable that 777X is a re-optimised aircraft with a new wing and new engine.

"That's not just the same as only optimising the engine for example. We're very comfortable with this position," says Nuttall.

Related Links: