Maximum take-off weight (MTOW), payload and range of the proposed Boeing 747X and X Stretch Freighter has been raised after requests from the customer group formed by the company to help focus requirements for the 747 derivative.

Although Boeing declines to confirm the changes, industry sources say MTOW for both freighter versions has been raised by 9,990kg (22,000lb), increasing the range of the stretched variant to 8,760km (4,735nm) and the baseline 747X to 11,050km. Net payload capability increases to 142,000kg for the Stretch while the 747X increases to 123,000kg. Sources also confirm that the MTOW of the passenger versions of the baseline and stretched models remains the same as previous proposals at around 473,520kg.

The effect of the weight increase is not expected to cause significant problems to the General Electric-Pratt & Whitney Engine Alliance GP7100 family which is being developed to cover the 67,000-73,000lb-thrust (300-325kN) range. The move could, however, pose development issues for the Rolls-Royce Trent 600 which is aimed at the 67,000-70,000lb range for both the 747X family and the longer range 767-400ER. Boeing says: "We are still completing calculations on the need for additional engine thrust."

Source: Flight International