Proposals show significant increase in range and payload

Boeing has confirmed it is considering studies of a more capable 747 variant, provisionally dubbed the 747-800X, with range and payload greater than anything since the abandoned stretched models of the mid-1990s.

The -800X studies have evolved from the -400XQLR (Quieter Longer Range) proposal which did not have sufficient range to attract real airline interest. Boeing believes the potential changes from the baseline -400 are now so great that the study merits renaming it the -800X. The label leapfrogs the proposed 747-500X/600X models, as well as the "747 look-alike" 747-700X all-new large aircraft proposal of 1996 which was designed to counter the Airbus A380-800.

"We also didn't want to leave the image of a warmed-over QLR," says product development vice-president Dan Mooney. "We haven't settled on the market or timing yet." Mooney says a possible airline consensus on the outline -800X proposal could allow Boeing to "set a stake in the ground" on the project towards the end of the first quarter of next year. The -800X is "something we haven't considered before", he says, and is "a nice balance between getting more range and still getting more revenue using the aircraft".

The basic proposal involves combining aerodynamic and structural changes studied for the QLR with additional tail fuel and a 2m (6.5ft) balancing four-frame fuselage stretch forward of the wing, where both main and upper decks would be extended (Flight International, 29 October-4 November).

Mooney says the additional fuel, believed to be around 3,790 litres (1,000USgal), would be housed in extra tankage created in the outboard sections of the horizontal stabiliser, as well as forward of the stabiliser main spar. It would not involve adding fuel to the vertical fin. The extra fuel would provide up to 14,800km (8,000nm) range and make space for 20 to 40 more seats.

Modifications introduced for noise reduction, such as raked wingtips and drooped ailerons, also had better-than-expected performance when combined with other aerodynamic changes such as trailing edge wedges, says Mooney. "It has led us to see what's beyond QLR. So now we are back in a product development phase to see what opportunities we might have with new or derivative propulsion systems." Powerplant candidates are in the 62,000-64,000lb (276-285kN) thrust bracket and include the Rolls-Royce Trent 600, General Electric NGen6 CF6-80 development and Pratt & Whitney PW4000 derivatives.

Source: Flight International