Boeing expects to complete windtunnel tests of a stretched, 500-seater 747 by the end of the year and, pending the successful conclusion of business case studies and sufficient customer commitments, says it could launch the aircraft by mid-1999.

Boeing, which celebrated 30 years of 747 assembly earlier this month, shelved much more ambitious 747-500X/600X derivatives in January 1997. The company warns that "-nobody is anxious to buy any big aircraft now, and it's going to take a lot of hard work to complete the business case". The economic turmoil in Asia, home of the largest 747-400 marketplace, continues to deter Boeing's growth plans and appears to have pushed back the proposed debut of the 747-400X, which was firmly defined last May (Flight International, June 3-9).

The heavyweight -400X, with a maximum take-off weight of 409,500kg (910,000lb) and a range of up to 14,260km, was originally offered for delivery as early as October 2000. Boeing director of product marketing, Joe Ozimek, says however: "The earliest we could deliver the 910,000lb aircraft would be the third or fourth quarter of 2001.

"The aircraft is on firm offer and we are talking to several customers which are real potentials. We are waiting for someone to order it so we can launch it," he adds.

The newest stretch configuration is for an aircraft about 80m (260ft) long with a wingspan of 70m. The bulk of the proposed changes would take place in the wingbox, which is expected to be 1.06m longer to accommodate 2.3m wing root inserts. The wing would also be modified with an MD-11-style trailing edge wedge, along with "-other types of tip treatments and some aerodynamic clean-ups. We have been very impressed by the test results so far. These improvements indicated we could get a couple of per cent out of the aircraft", Ozimek adds.

Compared with the 12% improvement in seat kilometre costs estimated for the more radical -500X/600X, Boeing estimates the latest changes could result in a "7-10%" improvement over the baseline -400.

While the focus remains on the -400X for the immediate future, the stretch with the reworked wing is the next priority "-if Boeing can close the price loop", says Ozimek.

"We'll pursue windtunnel testing through to the end of the year. If we can get enough customers to commit by the second or third quarter of 1999, we would decide to proceed with a target entry-into-service of late 2003," he adds.

A derivative using the new wing, engines and centre fuselage of the stretched version could also "fall out" of the stretch. This aircraft would nominally seat around 435, compared to 416 on the -400, and would have longer range potential than the larger stretch.

Source: Flight International