Boeing is struggling to get its proposed 777-200X/ 300X growth derivatives off the ground in time for the Paris air show, as the company considers a further increase to the maximum take-off-weight (MTOW) of the aircraft to meet airline range and payload demands.
The US manufacturer is discussing raising the 777-200X's MTOW to 333,690kg and increasing the wingspan extension from 1.38m to 3.96m. The 6,810kg jump in MTOW and additional 1.29m wingtip extensions are needed for the required increase in fuel capacity and lift.
The proposed changes are in response to the longer-range needs of potential launch customers in South-East Asia. Singapore Airlines (SIA) wants the aircraft to be able to fly non-stop, at any time of year, to Los Angeles (a still-air distance of 16,260km (8,790nm)), carrying 206 passengers. As now configured, the 777-200X would fall short of SIA's specified requirements, particularly in winter, on return legs from Los Angeles.
Furthermore, say airline sources, the aircraft would have to be fitted with an auxiliary belly fuel tank, occupying valuable underfloor cargo space.
Any further increase in the aircraft's MTOW would require major structural modifications and a higher engine-thrust level than the 454kN (102,000lb) now planned for the -200X. "We're getting close to that point where, if any extra weight is added for whatever reason, then everything has to change," says Boeing vice-president of product strategy, Mike Bair.
Engine suppliers are faced with a similar major redesign of existing powerplants to go beyond 454kN.
Some manufacturers are already balking at the estimated $350-500 million investment required to expand existing engines to 454kN. General Electric will not commit to the 777-200X until it can see sufficient demand for its planned GE90-102B, while Pratt & Whitney is concentrating for now on the smaller 436kN PW4098.
Rolls-Royce says that it plans to have its Trent 8102 ready by January 2001.
Source: Flight International
