Aeronautics and astronautics – Aircraft structure – Details
Reexamination Certificate
1999-04-05
2001-09-25
Swiatek, Robert P. (Department: 3641)
Aeronautics and astronautics
Aircraft structure
Details
C244S216000, C244S219000, C244S04500R
Reexamination Certificate
active
06293497
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an aircraft configuration and, more particularly, to a commercial jet aircraft utilizing a slotted cruise airfoil and a wing with very low sweep compared to the sweep of more conventional jet aircraft, achieving the same cruise speed.
BACKGROUND OF THE INVENTION
This invention relates to an aircraft configuration utilizing improved laminar flow. If laminar flow is achieved, aircraft drag, manufacturing costs, and operating costs are substantially reduced. U.S. Pat. No. 4,575,030, entitled, “Laminar Flow Control Airfoil” by L. B. Gratzer, and is assigned to the assignee of this invention. The Gratzer patent provides information on development which includes, among other techniques, suction surfaces and slots to promote natural laminar flow over a main box region of a wing.
SUMMARY OF THE INVENTION
An aspect of the wing of this invention is that it incorporates a slotted cruise airfoil. Slotted cruise airfoil technology that we have developed allows us to produce an unswept, or substantially unswept, wing that achieves the same cruise speed as today's conventional airplanes with higher sweep.
This invention, this technology allows the wing boundary layer to negotiate a strong recovery gradient closer to the wing trailing edge. The result is about a cruise speed of Mach=0.78, but with a straight wing. It also means that for the same lift, the super velocities over the top of the wing can be lower. With very low sweep and this type of cruise pressure distribution, natural laminar flow can easily be obtained. Lower-surface Krueger flaps are installed to increase lift capability for low-speed operation and to protect the wing leading edge from bugs during takeoff and landing to prevent spoiling natural laminar flow.
In another aspect of the invention, heat is transferred from the leading edges of the wing and/or of the main flap to increase the extent of the natural laminar flow.
In still another aspect of this invention, a high wing arrangement allows more freedom for installation of higher bypass ratio engines. An advanced geared fan engine, by-pass ratio 12 or higher, is a possibility that could be easily installed under the high wing. The lower super velocities of the slotted cruise airfoil make the body shock problem associated with many high wing airplanes less of a concern here.
The slotted cruise wing airfoil and the straight wing allow us to modularize the wing and the body so that we can develop a family of airplanes by intermixing different bodies with different wings.
Another aspect of this invention is to reduce costs. The unsweeping of the wing significantly changes the manufacturing processes, reduces manufacturing costs and flow time from detail part fabrication to airplane delivery. The system architecture is all new rather than a major remodeling of a systems architecture from an exiting airplane. It is a top down approach geared towards the requirements of this airplane. Components from existing products will be used whenever they satisfy the requirements of this airplane. The payload systems allow for flexible interiors and extensive use of molded panels.
Still another aspect of this invention is that the expected fuel bum per seat for this type of an airplane is 20% to 30% less than on current jet airplanes, this can be associated with considerable reduction of emission of greenhouse gases.
There is very little difference in ditching capability between a low wing airplane and a high wing airplane. In both cases, the body provides the vast majority of the flotation. The wing provides some stability to prevent the ditched airplane from rolling over.
Another aspect of this invention is that a low wing version with aft mounted engines is also possible. It would feature many, if not most of the above advantages.
REFERENCES:
patent: 1770575 (1930-07-01), Ksoll
patent: 2891740 (1959-06-01), Campbell
patent: 3447763 (1969-06-01), Allcock
patent: 4117996 (1978-10-01), Sherman
patent: 4700911 (1987-10-01), Zimmer
patent: 4784355 (1988-11-01), Brine
patent: 4856735 (1989-08-01), Lotz et al.
patent: 5167383 (1992-12-01), Nozaki
Drella, Mark, “Design and Optimization Method for Multi-Elements Airfoils,” MIT Department of Aeronautics and Astronautics, pp. 7 and 9, figures 3, 7, and 8.
Anast Peter Z.
Kelley-Wickemeyer Robert H.
McLean James Douglas
Seidel Gerhard E.
Nelson Lawrence W.
Swiatek Robert P.
The Boeing Company
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