Boeing is on a fast track to defining the specification and timing for its high-speed airliner, as new details emerge of powerplant offerings from engine manufacturers

Boeing plans to complete the initial definition of its near-sonic commercial transport concept by the end of December as part of its overall strategy to offer the aircraft for service entry in the 2006 to 2008 timeframe.

"We'd like to get the fundamentals such as capacity, target range and basic operating cost data established by the end of this year, and head on from there," says Boeing vice president of marketing for new aircraft, John Roundhill. Once these basic parameters are established, Boeing and its airline working group will begin defining the systems requirements and the interior architecture in 2002.

"We will also be working on the market estimate and the forecast," adds Roundhill who says the market will drive the timing. Other key studies being undertaken include assessments of the cargo potential of the sonic cruiser, as the concept is widely dubbed, as well as a string of technical trade-off studies. These will evaluate the time to market and cost benefit of using off-the-shelf equipment and systems against the merits of newer technology. "Part of the effort next year is to make sure the aircraft is serviceable and accessible, and we are looking at a number of alternatives to address attaching jetways to the fuselage because of the canard."

Details of the engine studies for the sonic cruiser are also emerging. Rolls-Royce director of Boeing programmes Phil Hopton says the UK engine maker is evaluating three main triple-shaft concepts including a "777-based offering in Trent 800 style, which doesn't quite do it in terms of thrust, and a more advanced concept aimed at entry into service around 2008". Hopton says a third concept is "the ultimate sort of engine we could do".

The biggest challenge, says Hopton, is installation of the large fan-diameter engine within the wing structure, and integration with the long-duct inlet. The company is studying blow-in and blow-out doors to help control inlet flow at high subsonic cruise speeds, and is exploring "more novel ideas like a two-stage fan or even a tandem fan". It is also studying variable-area nozzles to help optimise the engine cycle for best cruise performance, and plans to include technical developments from the European Commission's Affordable Near-Term Low Emissions (ANTLE) research project.

General Electric, though remaining tight-lipped about its proposals, is known to be focusing on a range of derivatives using the 10-stage high pressure compressor of the GE90 and the nine-stage successor in development for the higher thrust GE90-115B. Pratt & Whitney is offering a PW4098-based derivative as well as a new centreline turbofan and a "novel" advanced concept geared towards a higher Mach number aircraft (Flight International, 15-21 May).

Source: Flight International