Boeing is considering range and lift enhancements to the proposed 777-200X/300X to improve field performance. Programme officials are seeking at the same time to stretch pre-launch funding and allow more time to firm up potential customer support.
The company is studying design refinements to the 777 in an effort to shorten the take-off run of the planned ultra-long-range -200X/ 300X version. It aims to reduce the aircraft's required field length from 3,660m (12,000ft) to about 3,050m to overcome restrictions such as those on the west-bound runways at Los Angeles.
Among changes being considered are new outer-wing split flaps for improved lift and the adoption of semi-lever articulated landing gear to increase rotation angle and reduce take-off speed. "All of the above are being looked at," confirms Boeing marketing director Bob Sancewich, but he adds that any improvements must be balanced against cost.
The 777-200X/300X operating at maximum take-off weight (MTOW) would face thrust limitations under certain hot conditions. The 454kN (102,000lb)- thrust Rolls-Royce Trent 8104 will be the largest engine available on the twinjet and any further growth is limited by the size of the existing 2.79m-diameter compressor fan.
Boeing officials, in the meantime, are hoping to extend existing funding and avoid having to go back to the president's office in mid-January to ask for additional money. The company is still trying to muster sufficient market support to launch the programme and sources are warning that any further slippage beyond May 1998 will affect the -200X's planned entry-into-service date of September 2000.
The company insists that its study of new 413,140kg (910,000lb) MTOW growth derivatives of the 747, the -400X and longer-range -200X, while overlapping with the 777-200X and -300X, are complementary. "It is conceivable that we could do all four," claims Sancewich.
Longer-term and less of a priority is a stretched -400X powered by 65kN engines and an extended-range stretched -400Y with 67kN powerplants, seating an additional 80 passengers. While the former would retain the existing 747 wing and have a range of about 12,950km, the latter would feature a wing-root insert and a range increase of around 925km.
Source: Flight International
