Boeing 787 Dreamliner - Mark Wagner [67]
By March 2005 GE froze detailed design, clearing the way for the start of manufacturing of the first GEnx parts. Assembly of the first GEnx was now scheduled to start in October, with the first engine to test in March 2006. Tests on GE’s 747-100 flying test bed were set for the third quarter of 2006, with first flight on the 787 expected about a year later.
Seven engines were assigned to the 787 certification program, which encompassed three variants: the GEnx-54B for the 787-3, the GEnx-64B for the 787-8, and the GEnx-70B for the 787-9.
“It’s execution time. We’re cutting metal on all components and working the build process. We are even looking at ways to build them differently,” said GE Commercial Marketing General Manager Mike Wilking, who emphasized that despite the innovative use of more composites in the structure, as well as the blades, the GEnx was more evolutionary than revolutionary. “All the technologies in these engines are advanced and proven; there’s really nothing new in here,” he said.
The final design included a fan with just eighteen blades, as opposed to twenty-two on the GE90. “Just having eighteen blades cuts the scrubbing losses [aerodynamic interaction with the wake of the preceding blade], cuts weight, and improves noise reduction,” said Wilking. Despite the extensive use of composites, GE acknowledged that the engine was likely to be a “bit heavier” than the rival Trent 1000. “But we’re okay with that because we’re backing fuel burn and long-term performance retention,” he said.
The final configuration included a four-stage LP compressor, a ten-stage HP compressor, a two-stage HP turbine, and a seven-stage LP turbine, one more than in the GE90-94 from which it was derived. Other innovations include “endwall effects” or contouring to reduce pressure losses in the interstage areas between individual turbine and compressor stages.
Aside from extensive composites, the engine also included an array of advanced superalloys such as niobium silicide (NbSi) in the HP turbine, and intermetallic compounds such as titanium aluminide (TiAl), which, for the first time in any civil engine, was used in the sixth and seventh LP turbine stages. The GEnx also was designed with a scaled-up version of the twin annular preswirl (TAPS) combustor, developed for the CFM International Tech 56 technology program.
By mid-2005 Rolls-Royce had meanwhile begun construction work on a U.K. £30 million “58 bed” test site for the Trent 1000, and was getting ready to receive a flood of parts for the start of assembly of the first engine in November and the buildup to the beginning of test runs in February 2006.
Easily distinguished by its size compared to the 747-100’s standard Pratt & Whitney JT9Ds, General Electric’s GEnx-1B gets airborne for the first time, on February 23, 2006, on the company test bed at Victorville, California. In a twist of irony, the new engine became airborne within hours of the death of Brian Rowe, a former GE president who led the pivotal launch of the GE90, predecessor to the GEnx. Considered a risky move in its day, the GE90 go-ahead was described as “the gutsiest call I’ve ever seen at GE” by David Calhoun, a former GE vice chairman and formerly head of the aviation unit. General Electric
“It’s beginning to be very real,” said Rolls-Royce Director of Boeing Programs Dominic Horwood. “The design of the engine is essentially complete—there are still a few things to do on the external systems, but the propulsion configuration is firm with Boeing and we are on plan and on time.” An additional $42 million was allocated to development of an engine noise testing facility at NASA’s Stennis Space Center in Mississippi that was aimed at “mapping” the acoustics of the engine in 2007. Altitude tests were scheduled for mid-2006 at the Arnold Engineering