Guy Norris/LOS ANGELES
Boeing says it is still studying all-new large aircraft concepts, dubbed the Large Airplane Product Development (LAPD), despite its deliberate focus on 747 derivatives and opposition to more costly all-new concepts such as the the proposed Airbus A3XX.
"Boeing is studying a large aircraft," says the company's product marketing regional director, Jacki Caferro, who adds that the low-level work is aimed mainly at "just staying on top of what is happening in the market, and what is happening in technology". Caferro adds that "somewhere down the line, the airlines may want something with more capacity than the 747".
Until now, Boeing has maintained silence over any non-747 based derivative work in the large-aircraft arena. Since the company backed away from its New Large Airplane (NLA) activities in 1995, Boeing has publicly poured all its product development energies into 747 derivatives. The effort almost culminated in the 747-500X/600X project, scrapped in January 1997, but continues as the 747-400X investigation.
No details of the LAPD investigation have been revealed, but reports indicate that they include a variety of concepts and configurations. These range from 747 "lookalikes" and revised NLAs, to designs based on the former McDonnell Douglas MD-12 quad-jet and unconventional configurations like the Blended Wing Body.
News of the LAPD, unexpectedly revealed at the Speednews suppliers conference in Los Angeles, was also accompanied by the latest proposed configurations for the 747-400X studies. The baseline remains the 422,220kg (930,000lb) gross-weight long-range version of the current aircraft with a range capability of 14,800km (8,000nm).
The gross weight potential of the next growth step, a root wing insert -400X stretch, has increased to 482,600kg, based on favourable test data, says Caferro. Using the structural upgrades required for the -400X as a platform, Boeing is studying a stretch based around a new wing box and wing root inserts. The initial stretch was aimed at a 473,520kg model with a 14,430km range. According to Boeing, however, good test data suggests the weight of this variant could be raised 9,100kg, to increase capacity. "We are looking at ways to increase take-off and landing performance as well as improve fuel burn and noise," Caferro adds.
She also reveals that the trailing edge wedge modification flight, tested on a 747-400 late last year, produced an impressive 3.5% improvement in fuel consumption. The modification, based on performance recovery work originally developed by McDonnell Douglas for the MD-11, aft-loads the wing and improves performance in cruise. Unfortunately for Boeing, the tests "bent the trailing edge of the wing. So we got a very strong message that these devices can't be retrofitted," says Caferro.
Source: Flight International
