Aeronautics and astronautics – Aircraft – heavier-than-air – Airplane sustained
Reexamination Certificate
2002-05-06
2004-03-16
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft, heavier-than-air
Airplane sustained
C244S04500R, C244S11700R, C244S118500, C244S119000
Reexamination Certificate
active
06705567
ABSTRACT:
TECHNICAL FIELD
This present invention relates generally to tandem wing aircraft and methods for manufacturing and operating such aircraft.
BACKGROUND
One goal of the commercial air transport industry is to convey passengers and cargo as quickly as possible from one point to another. Accordingly, many commercial transport aircraft operate at cruise Mach numbers of approximately 0.8-0.85. As the time constraints placed on air carriers and their customers increase, it would be advantageous to economically transport passengers and cargo at higher speeds. However, aircraft flying at transonic or supersonic speeds (greater than about Mach 0.85) have greater relative thrust requirements than comparably sized subsonic aircraft. To generate sufficient thrust at high altitudes and Mach numbers, while reducing the corresponding increase in drag, conventional transonic and supersonic aircraft include low bypass ratio turbofan engines or straight turbojet engines. Such configurations generally have a high specific fuel consumption at cruise conditions that generally outweighs any inherent advantage in aerodynamic efficiency, resulting in a net fuel efficiency significantly lower than that of lower speed aircraft. The low fuel efficiency can also result in increased atmospheric emissions.
FIGS. 1A and 1B
illustrate top isometric and bottom isometric views, respectively, of a supersonic cruise aircraft
10
a
in accordance with the prior art. The aircraft
10
a
can include a fuselage
13
a
, a delta wing
12
a
, a propulsion system
15
a
suspended from the wing
12
a
, and an aft-tailed pitch control arrangement
17
. Alternatively, the aircraft
10
a
can include a tail-less or canard pitch arrangement. In either configuration, the longitudinal distribution of the exposed cross-sectional area of the aircraft, and the longitudinal distribution of the planform area tend to dominate the transonic and supersonic wave drag (i.e., the increase in drag experienced beyond about Mach 0.85 due to air compressibility effects). Accordingly, the fuselage
13
a
can be long, thin, and “area-ruled” to reduce the effects of wave drag at supersonic speeds.
Area-ruling the fuselage
13
a
can result in a fuselage mid-region that is narrower than the forward and aft portions of the fuselage (i.e., a “waisted” configuration). Waisting the fuselage can compensate for the increased cross-sectional area resulting from the presence of the wing
12
a
and the propulsion system
15
a
. The propulsion system
15
a
can include four engine nacelle pods
16
a
mounted beneath the wing
12
a
to minimize adverse aerodynamic interference drag and to separate the rotating machinery of the engines from the main wing spar and the fuel tanks located in the wing. Noise suppressor nozzles
18
a
are typically cantilevered well beyond a trailing edge of the wing
12
a
, and can accordingly result in large cantilever loads on the wing
12
a.
FIGS. 1C-E
illustrate a side view, plan view and fuselage cross-sectional view, respectively, of a configuration for a high-speed transonic cruise transport aircraft
10
b
having a fuselage
13
b
, a swept wing
12
b
, and engine nacelles
16
b
suspended from the wing
12
b
in accordance with the prior art. The fuselage
13
b
has a significantly narrowed or waisted portion proximate to a wing/body junction
19
. Accordingly, the fuselage
13
b
is configured to avoid or at least reduce increased drag in a manner generally similar to that described above with reference to
FIGS. 1A and 1B
. This configuration may suffer from several drawbacks, including increased structural weight, increased risk of flutter loads, and a reduced payload capacity. The configurations shown in
FIGS. 1A-1E
can be structurally inefficient and can have reduced payload capacities as a result of the fuselage waisting required to reduce transonic and supersonic drag.
SUMMARY
The present invention is directed toward tandem wing aircraft and methods for manufacturing and operating such aircraft. An aircraft in accordance with one aspect of the invention includes a fuselage having a first portion and a second portion projecting upwardly from the first portion. The first portion houses a passenger deck and the second portion is positioned above the passenger deck. A first wing extends outwardly from the first portion of the fuselage and a second wing extends outwardly from the second portion of the fuselage. The second wing is positioned above and forward of the first wing.
In a further aspect of the invention, the fuselage can include a plurality of passenger doors simultaneously accessible to ground-based passenger load/unload equipment. At least one of the passenger doors is positioned beneath the second wing. In still further aspect of the invention, the aircraft can have a forward portion, an aft portion, and an intermediate portion between the forward and aft portions, with a cross-sectional area distribution of the aircraft increasing at least approximately monotonically from the forward portion to the intermediate portion, and decreasing at least approximately monotonically from the intermediate portion to the aft portion.
The invention is also directed toward a method for loading and unloading an aircraft and includes positioning a first passenger load/unload device adjacent to a first passenger door of the aircraft, with the aircraft having a first wing and a second wing positioned forward of and above the first wing. The method can further include positioning a second passenger load/unload device adjacent to a second passenger door of the aircraft while the second passenger load/unload device is positioned beneath the second wing of the aircraft and while the first passenger load/unload device is positioned adjacent to the first passenger door. The method can still further include simultaneously moving passengers through both the first and second passenger doors.
The invention is still further directed to a method for manufacturing an aircraft. The method can include providing a fuselage having a first portion and a second portion projecting upwardly from the first portion, with the first portion housing a passenger deck and the second portion being positioned above the passenger deck. The method can further include mounting a first wing to the first portion of the fuselage and mounting a second wing to the second portion of the fuselage with the second wing being positioned above and forward of the first wing. In a further aspect of the invention, the method can further include providing the fuselage with a plurality of passenger doors that are simultaneously accessible to ground-based passenger load/unload equipment, with at least one of the passenger doors being positioned beneath the second wing.
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“Prototypes: Comparative Design Analysis,” Aviation Week & Space Technology, Sep. 17, 1990 (p. 45).
Scott, William, B., “YF-23A Previews Design Features of Future Fighters,” Aviation Week & Space Technology, Jul. 2, 1990 (pp. 16-21).
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Dong Lawrence Y.
Sankrithi Mithra M. K. V.
Eldred J. Woodrow
Perkins Coie LLP
The Boeing Company
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