Most commentators expect GE’s conceptual GE9X to be chosen for Boeing’s 777X, allowing GE to retain the exclusivity it currently holds with its GE90 engine that powers the 777-300ER, -200LR and Freighter. However, proposals from other aircraft engine manufacturers – Rolls-Royce and Pratt & Whitney – will create strong competition to power the 777X family of aircraft.
Rolls-Royce’s RB3025 engine is rated at 99,500lbs with a 337cm (132.5in) fan for the baseline 407-seat 777-9X, giving the engine a bypass ratio of 12:1. RB3025 offers an improvement in fuel burn of more than 10% compared to the current GE90-115B engine and 15% compared to the Trent 800 engine that powers early models of 777 aircrafts.
The new RB3025 engine concept provides a low specific thrust and "excellent" propulsive efficiency, in conjunction with a 62:1 overall pressure ratio. If achieved, this would be the highest overall pressure ratio achieved in a commercial turbofan engine.
Robert Nuttall, Rolls Royce vice-president of strategic marketing stated that although the RB3025 builds on the Trent 1000 and XWB engines, the concept is built around the company’s Advance3 environmentally friendly engine (EFE) technology development program. This includes a Trent 1000-derived core, composite fan, lean-burn combustor and advanced materials in the combustor and high-pressure elements of the core.
Boeing is aiming for the end of 2012 official launch from the company's board of directors. The company has not indicated whether it will offer several engine choices for the 777X.
The 777-8X concept, a 353-seat stretch of the 777-200ER, will have a thrust requirement of 88,000lb and Rolls plans to have a "single bill of materials" for the RB3025 engines on both the -8X and larger -9X, whereby the lower thrust can be achieved through an easy engine de-rate. Rolls-Royce will work with the Boeing design team to optimize the engine around the conceptual aircraft.
Although Rolls-Royce has opposed aircraft re-engining programs in the past, it will actively promote the RB3025 for the re-winged, re-engined 777X. Rolls-Royce will cite the aircraft's new composite wing as an essential part of achieving the general optimization the engine maker favors when making big investments. Nuttall said,
"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 optimizing the engine for example. We're very comfortable with this position”.