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Joined: Wed Nov 01, 2000 7:17 am

747 - What Could Have Been

Wed Aug 01, 2001 11:40 am

Found this interesting article eventhough it is now pointless:


Thicker wing will boost aerodynamic efficiency and streamline production processes

Boeing has decided to boost the aerodynamic efficiency of the wing on the planned 747X by reshaping the full span in order to apply 777-and-beyond supercritical airfoil technology.

Boeing has built a mockup of passenger berths which could be installed in the overhead space of the aft passenger cabin on planned 747X aircraft.
The company had intended to significantly modify the 747 wing for the 747X model with features such as a 105-in. wing root insert and new wingtip design, but recently decided to recontour the entire airfoil to meet program requirements for aerodynamic efficiency.

The planform and layout of wing structural members would remain the same as for the 747-400 to save cost and development time, according to program officials.

The recontouring of the wing will result in an improvement in aerodynamic efficiency of about 3-4% for the 747X, but it also will provide engineers with increased latitude in making internal changes to update wing manufacturing and assembly processes.

ALSO, BOEING IS CONSIDERING connecting the standard upstairs passenger seating area in the forward end of the aircraft to what would be newly utilized space in an area above the main cabin in the aft fuselage. That area is intended to accommodate modular units for crew rest, galley cart storage and passenger berths.

The wing planform remains the same as earlier designs for the 747X, but cross-sections of typical outboard wing sections show a new foil representing 747X 2001 technology and the existing 747 foil design.

The company is developing plans for a 430-
passenger 747X that would be slightly longer than a -400 and have a range of 8,975 naut. mi., as well as a stretch 747X that would be 31.5 ft. longer and carry up to 522 passengers. The 747X program, which has received no orders to date, has not yet been formally launched.

Walter B. Gillette, Boeing 747X program manager, said the wing change--which will increase cruise speed of the aircraft to about Mach 0.87--will provide an opportunity to utilize the latest wing materials and manufacturing technology for the new models. The increased thickness of the wing cross-section also provides designers with more options for system installations. The wing has an area of 6,821 sq. ft. and a span 8% greater than on the current model. Wing sweep at one-quarter chord is 37.5 deg.

Long-range cruise speed for the -400 is Mach 0.85, while the previously planned cruise speed for the 747X was Mach 0.86.

Gillette said Boeing is in the final stages of wind-tunnel testing the new wing design, which will not include the previously planned blunt trailing edge. That wedge design, used on the MD-11, is considered most effective when implemented on older wing designs (AW&ST Jan. 1, p. 28).

While the aerodynamic contour of the wing will be improved, the planform and the layout of the spars, ribs and stringers will remain the same, according to Gillette. However, the program will evaluate different means of building 747X wings, such as the use of composite materials and one-piece aluminum machined structures.

The wing of the new model would also incorporate 777-type single-slot flaps to replace the heavier and more complex triple-slotted 747 flaps. Boeing said the new high-lift system would reduce costs, maintenance requirements and aircraft weight by up to about 5,000 lb.

The raked wingtip is the baseline design for the 747X, although program officials are still studying data that could influence a final wingtip decision. The alternative design is a blended winglet. Other features of the new model include:

Fly-by-wire controls for ailerons and spoilers.

A pitch stability augmentation system.

An upgraded cockpit similar to that of the 777, including an electronic checklist and enhanced maintenance terminal.

New General Electric and Pratt & Whitney Engine Alliance GP7100 or Rolls-Royce Trent 600 engines with 68,000 lb. of thrust.
Gillette said the 22% larger wing of the 747X has provided the lift required to handle the extra weight of additional accommodations planned for the aft overhead space.

An overhead passageway, with a vertical height of about 6 ft., would be flanked by open areas in which the modular crew rest, galley cart storage and passenger berth units could be installed.Placing the units there, instead of on the main cabin floor, would allow carriers to put the maximum number of passenger seats in the revenue space of the cabin below.

To achieve the required head height in the upper passageway, rudder cables and environmental system ducts would be relocated within the overhead section, which would not affect the ceiling height of the main cabin.

A flight on the long-range, standard-length 747X model could require placing up to 100 galley carts on board. The first meal service would be placed in galley areas, while the second and third meals would be in 65 carts stored in the overhead area. The aircraft would have two galley cart elevators for redundancy.

ONE AIRLINE OFFICIAL touring the 747X overhead mockup at Boeing has commented on the possibility of placing the crew rest area and galley cart storage on the main passenger deck, and filling the aft overhead area with berths for first-class passengers. The overhead space could accommodate up to 60 passenger berths.

An official of another carrier noted the possibility of including about 60 business-class seats on primary passenger decks, with half of those seats held by first-class passengers who would also be assigned berths. In such an arrangement, the galley carts and crew rest area could remain in the overhead space.

Boeing is also considering connecting the upstairs passenger seating area in the forward fuselage to the aft overhead space, which would require relocating air conditioning system components now occupying that space on -400s. In such a case, Gillette said, an airline might consider designating both upper-level areas for first-class passenger use.

THE EXTRA WEIGHT OF THE BERTH, storage or rest area facilities installed in the aft overhead would result in the loss of about 200 mi. of range, but program officials have increased the aerodynamic target of the 747X design to regain that capability. If an airline customer decided not to use the overhead space, the carrier would gain an additional 200 mi. above the 747X standard-length fuselage design range.

Although the 747X program has not received any orders, the program is working on a schedule that calls for a firm configuration date next March, and certification in August 2005, with initial deliveries beginning the following month.

The program schedule also calls for increasing the number of employees to several hundred or more by the end of this year, and to begin ramping-up to significant numbers of program personnel next March.

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