General Electric's GENX engine is a fifth-generation GE90 derivative incorporating a 2.82m (111in)-diameter high-flow swept composite fan, possibly with as few as 20 blades compared with 22 for the GE90. "We went in with a low-risk design to Boeing, while injecting some new technology," says GE engineering vice-president and general manager Rick Stanley.

New features include counter-rotating high- and low- pressure (HP/LP) spools; an advanced 10-stage HP compressor based on the aerodynamics demonstrated on the latest "Core 7" development version of the GE90-94B; a single annular, twin annular pre-swirl combustor; and a low blade-count, seven-stage LP turbine. Design freeze for what is also being seen as GE's next-generation CF6 replacement is expected by early 2005 and certification in mid-2007.

The Rolls-Royce Trent 1000 is the fifth member of the Trent family, and is based largely on the Trent 900 design. "We think we have the right balance of evolved Trent heritage with a significant number of new features," says civil aerospace president Mike Terrett. A key feature is the 2.85m diameter, low-speed swept fan, which will be rooted in a smaller radius hub to lower the hub/tip ratio. It will also incorporate an eight-stage intermediate pressure (IP) compressor, six-stage counter-rotating high-pressure compressor, advanced low-emissions combustor, single-stage HP and IP turbines and six-stage LP turbine.

Taking advantage of the triple shaft design, power for the aircraft will be taken off the back end of the IP compressor rather than the usual front end of the HP compressor, allowing a greater stability margin and lower flight and ground idle thrust.

Source: Flight International