Graham Warwick/WASHINGTON DCPaul Lewis/SEATTLE
Boeing is discussing with airlines five possible 747 derivatives as it moves towards a decision in early 1998 on which (if any) option to pursue. Airlines are being shown study aircraft with various combinations of capacities for up to 500 passengers and ranges of up to 15,400km (8,300nm).
Options being studied would be cheaper to develop than the previously proposed 747-500X/600X, and the aircraft could be in service as early as December 2001, ahead of Airbus Industrie's planned A3XX large airliner.
Boeing started out by studying an increased-gross-weight derivative of the 747-400, now dubbed the -400X, and a stretched version of the 747-400X, but it has added three potential variants in a bid to gather more data from possible customers. As envisaged, the 747-400X would have a gross-weight increase of up to 32,000kg (to 426,000kg) and a range increase of around 1,800km (to 15,200km). The -400XStretch would accommodate 485 passengers (an increase of 65), with a range close to that of the basic -400.
The company is now considering the possibility of a wing-root insert, as well as a wingspan fillet, to create the 747-400RI and -400RI Stretch. The insert, which has yet to be defined fully, would increase fuel capacity and gross-weight capability. A new fuselage centre-section would result in a small stretch, increasing seating capacity by 15 (to 435 in the -400RI and 500 on the -400RI Stretch). The -400RI would have a range of almost 15,400km, while the Stretch - which could have a gross weight approaching 472,000kg - would have a range of 14,000km.
The Ìfth option being discussed with airlines is to mate the fuselage of the 747-200, with its short upper-deck, to the wing of the 747-400 freighter. This would produce an aircraft able to carry 375 passengers over 14,800km, and it is being viewed as a competitor for the Airbus A340-600.
This proposed derivative is variously referred to as the -400 plus, the "L2R" for lightweight long-range, or the "-200IGWX". This latter version is viewed as the cheapest and least complicated solution, entailing only a modest increase in maximum take-off weight (MTOW), to around 400,900kg, and would not require a new, higher-thrust, powerplant. To minimise any weight increase, Boeing is being encouraged to consider the use of composite floor beams, radial tyres and rail-mounted supplementary fuel tanks in place of its traditional and slightly heavier beam-suspended tanks.
Asian carriers, including Cathay Pacific Airways, are showing interest in the new, lighter, longer-range version of the 747. The Hong Kong carrier is looking for an aircraft with which it could operate full payloads in and out of Los Angeles all year round, and permit non-stop flights to New York.
"We're talking to Boeing about upping the MTOW and increasing the fuel," says Cathay chairman Peter Sutch. Boeing has also revived work which could lead to the rebirth of the New Large Airplane (Flight International, 10-16 September).
Source: Flight International
