Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Reexamination Certificate
2003-05-14
2004-03-23
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
C244S120000
Reexamination Certificate
active
06708924
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to aircraft and more particularly to an aircraft having a body that is at least partially constructed from a plurality of longitudinally or laterally extending body structures to provide a family of aircraft with each family member having a different cargo capacity.
BACKGROUND OF THE INVENTION
Purchasers of modern airline and cargo aircraft typically require a wide range of capacities to suit the diverse needs of their markets. One option for satisfying these needs is to provide several uniquely designed aircraft, with each design being optimized for an equally unique market. This approach, however, is extremely costly, not only in terms of development and manufacture, but also in terms of their operation, maintenance and servicing. Instead, capacity variations in conventional airline and cargo aircraft are achieved by adding or removing pieces of a constant diameter tubular fuselage section.
In contrast, blended wing body aircraft designs, also known as flying wing designs, lack a “constant” section whose length can be varied so as to provide the desired variation in capacity. Furthermore, the careful shaping of these designs to permit efficient flight at transonic Mach speeds and adequate internal volume negates the incorporation of simplistic changes to the design that add capacity yet unacceptably effect the balance of the aircraft due to the wing sweep that is required at high transonic cruise speeds. Such changes also tend to negatively effect the lofting and aerodynamics of alternate capacity versions.
U.S. Pat. No. 5,909,858 to Hawley discloses on solution for varying the capacity of a blended wing body aircraft. The Hawley design employs a variable size body, a pair of wing assemblies and a pair of transition sections. The body is broken up into a plurality of longitudinally extending segments that are based on a single design but which are mirrored across the centerline of the aircraft. Variable capacity is achieved by simply adding or subtracting pairs the segments from the body. The transition section has a negative sweep angle and couples each side of the body of the aircraft to one of the wing assemblies. While the identically configured segments permit the preservation of a common wing assembly and greatly reduce costs associated with the design, tooling, manufacture and maintenance of the aircraft, several drawbacks of this configuration have been noted.
One such drawback concerns the sharp discontinuity in the wing chord between the wing and the body of the aircraft. This results in a lift distribution that can be unfavorable to drag and stall characteristics. Furthermore, the balance of the aircraft is unlikely to be retained over several differently sized configurations. Accordingly, there remains a need in the art for a blended wing body aircraft having a modular construction that permits easy and cost-effective variations in the size of the aircraft yet which retains balance, aerodynamic loft and aerodynamic performance.
SUMMARY OF THE INVENTION
In one preferred form, the present invention provides a blended wing body aircraft having a pair of aircraft wings and an aircraft body. The aircraft body has a centerbody cabin formed from a plurality of body structures that include a pair of end body structures and at least one intermediate body structure. Each of the plurality of body structures defines a cargo compartment and are arranged about a centerline of the centerbody cabin such that each of the end body structures are juxtaposed between the at least one intermediate body structure and one of the aircraft wings.
In another preferred form, the present invention provides a blended wing body aircraft having a pair of aircraft wings and an aircraft body that is at least partially formed from a plurality of longitudinally-extending body structures. Each of the body structures on a first side of a centerline of the aircraft body is uniquely configured and arranged generally parallel to the centerline of the aircraft body. Each of the body structures on a second side of the centerline of the aircraft body is a mirror-image of an associated one of the body structures on the first side of the centerline of the aircraft body.
In another preferred form, the present invention provides a blended wing body aircraft having a pair of aircraft wings, an aircraft body and a propulsion unit. The aircraft body has a centerbody cabin, which is constructed from a plurality of body structures, and an aft centerbody cabin, which is coupled to a rearward end of the centerbody cabin. The propulsion unit is coupled to the aft centerbody cabin.
In another preferred form, the present invention provides a blended wing body aircraft having a pair of aircraft wings and an aircraft body that is at least partially formed from a plurality of longitudinally-extending body structures. Each of the body structures that are positioned such that their body structure centerline is not coincident with a centerline of the aircraft body includes a tip portion that forms a portion of the leading edge of the blended wing body aircraft. The tip portion has an inner edge with a first portion that extends outwardly away from a centerline of an associated one of the body structures and a second portion that is coupled to the first portion and extends forwardly and outwardly toward the leading edge of the blended wing body aircraft.
In yet another preferred form, the present invention provides a blended wing body aircraft having a pair of aircraft wings and an aircraft body that is at least partially formed from a plurality of longitudinally-extending body structures and a pair of leading edge panels. Each of the body structures that are positioned such that their body structure centerline is not coincident with a centerline of the aircraft body includes a tip portion that terminates rearwardly of a leading edge of the blended wing body aircraft. The tip portion has an inner edge with a first portion that extends outwardly away from a centerline of the aircraft body. Each leading edge panel is coupled to a portion of the body structures and one of the aircraft wings and forms at least a portion of a leading edge of the blended wing body aircraft.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
REFERENCES:
patent: 3761041 (1973-09-01), Putman
patent: 5082204 (1992-01-01), Croston
patent: 5813628 (1998-09-01), Hahl
patent: 5909858 (1999-06-01), Hawley
patent: 5975464 (1999-11-01), Rutan
patent: 6065720 (2000-05-01), Ash et al.
patent: 6070831 (2000-06-01), Vassiliev et al.
patent: 6098922 (2000-08-01), Hahl
patent: 6129308 (2000-10-01), Nastasi et al.
patent: 6568632 (2003-05-01), Page et al.
Article entitled: The Blended-Wing-Body, Nasa Facts FS-1997-07-24-LaRC, Jul. 1997.
Article entitled: Blended Wing Body (BWB), Aug. 7, 2002, from Boeing website: http://www.boeign.com/phantom/bwb.html.
Article entitled: Evolution of the Blended-Wing-Body Subsonic Transport, Aug. 7, 2002 from website: http://www.galcit.caltech.edu/Seminars/Fluids/CurrentFluids/Liebeck_abs.html.
Page Mark A.
Whitlock Jennifer P.
Wilks Matthew W.
Eldred J. Woodrow
Harness & Dickey & Pierce P.L.C.
The Boeing Company
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