Aeronautics and astronautics – Aircraft structure – Fuselage and body construction
Reexamination Certificate
2001-03-22
2003-06-10
Jordan, Charles T. (Department: 3641)
Aeronautics and astronautics
Aircraft structure
Fuselage and body construction
C244S05300R, C244S089000
Reexamination Certificate
active
06575406
ABSTRACT:
TECHNICAL FIELD
The disclosed embodiments relate to highly integrated and/or modular high-speed aircraft configurations and methods for designing and manufacturing such configurations.
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.
Conventional transonic and supersonic aircraft generally operate at very high jet velocities to generate sufficient thrust for take-off, which can result in significant airport and community noise problems. One approach to reducing the noise is to lengthen the engine inlet and nozzle ducts, and to also integrate noise abatement treatments with the ducts. One drawback with this approach is that such treatments generally increase the weight of the propulsion system, which can increase the wing structural loads and the susceptibility of the aircraft to wing flutter. If the wings are thickened to increase their weight capacity, the wave drag of the aircraft will also tend to increase. The increased weight of the wings also increases the amount of fuel that must be carried by the aircraft, which in turn increases the weight of the structure to support the fuel, which in turn requires still more fuel. Accordingly, it can be difficult to develop an effective, efficient, environmentally acceptable aircraft that operates at transonic and/or supersonic Mach numbers.
FIGS. 1A and 1B
illustrate top isometric and bottom isometric views, respectively, of a supersonic cruise aircraft
100
a
in accordance with the prior art. The aircraft
100
a
can include a fuselage
102
a
, delta wings
104
a
, a propulsion system
106
a
suspended from the wings
104
a
, and an aft-tailed pitch control arrangement
107
. Alternatively, the aircraft
100
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
102
a
can be long, thin, and “area-ruled” to reduce the effects of wave drag at supersonic speeds.
Area-ruling the fuselage
102
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 wings
104
a
and the propulsion system
106
a
. The propulsion system
106
a
can include four engine nacelle pods
108
a
mounted beneath the wing
104
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
110
a
are typically cantilevered well beyond a trailing edge
112
a
of the wing
104
a
, and can accordingly result in large cantilever loads on the wing
104
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
100
b
having a fuselage
102
b
, swept wings
104
b
, and engine nacelles
106
b
suspended from the wings
104
b
in accordance with prior art. The fuselage
102
b
has a significantly narrowed or waisted portion proximate to a wing/body junction
105
. Accordingly, the fuselage
102
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 high-speed aircraft and methods for aircraft manufacture. In one aspect of the invention, the aircraft can include a fuselage portion configured to carry a payload, and a wing portion depending from the fuselage portion. The wing portion can have a forward region with a leading edge, an aft region with a trailing edge, an upper surface, and a lower surface. The aircraft can further include a propulsion system at least proximate to the aft region of the wing portion, with at least part of the propulsion system positioned between the upper and lower surfaces of the wing portion. The propulsion system can include at least one inlet aperture positioned beneath the wing portion lower surface or above the wing portion upper surface, and at least one engine positioned aft of and vertically offset from, the at least one inlet aperture. The propulsion can further include at least one exhaust nozzle aft of the at least one engine. In a further aspect of the invention, the aircraft can further include at least one canard depending from the fuselage portion forward of the propulsion system. In another aspect of the invention, the fuselage portion can be elongated along a fuselage axis and the aircraft can include a pitch control surface having an aft trailing edge positioned inboard of the exhaust nozzle between the exhaust nozzle and the fuselage axis.
In still a further aspect of the invention, the propulsion system can include a rearwardly curving S-shaped duct between the inlet aperture and the engine. The aircraft can be configured to operate at a sustained cruise Mach number of from about 0.95 to about 0.99, or, alternatively, the aircraft can be configured to operate at a sustained cruise Mach number of from about 1.5 to about 3.0. The fuselage portion can include a forward region, an aft region adjacent to the propulsion system, and an intermediate region forward of the propulsion system between the forward and aft regions. The fuselage portion can taper continuously from the intermediate region to the aft region.
The invention is also directed to a modular aircraft system that can include a fuselage portion having a payload section, and a swept-wing portion depending from the fuselage portion and having an upper surface and a lower surface. The aircraft system can further include first and second nose portions interchangeably positionable on the fuselage portion, with the first nose portion being configured for subsonic flight up to about Mach 0.99 and the second nose portion being configured for supersonic flight. The system can further include first and second nacelles interchangeably coupleable to an aft part of the wing portion, with the first nacelle being configured for subsonic flight up to about Mach 0.99 and the second nacelle being configured for supersonic flight.
The invention is still further directed to a method for manufacturing an aircraft. In one aspect of the invention, the method can include attaching a wing portion to a fuselage portion with the wing p
Holzen Stephen
Jordan Charles T.
Perkins Coie LLP
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