Aeronautics and astronautics – Aircraft structure – Airfoil construction
Reexamination Certificate
2002-05-31
2004-04-27
Dinh, Tien (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Airfoil construction
C244S119000
Reexamination Certificate
active
06726149
ABSTRACT:
TECHNICAL FIELD
The following disclosure relates generally to derivative aircraft and, more particularly, to derivative aircraft wing configurations for high-speed aircraft and methods for designing and manufacturing such configurations.
BACKGROUND
Mission requirements typically dictate the configurations of aircraft. For example, aircraft with long-range mission requirements are typically configured to carry large quantities of fuel to increase their range between fuel stops. In addition, such aircraft are typically configured with relatively large wings to enable them to take off and land on conventional airport runways with heavy fuel loads. In contrast, aircraft with short-range mission requirements do not need to carry large quantities of fuel. Consequently, they typically require less wing area and have lower operating empty weights than long-range aircraft having comparable passenger capacities. As a result, using a long-range aircraft for a short flight can be very inefficient because the unnecessarily high empty weight of the long-range aircraft can result in poor fuel economy.
Accordingly, it would be advantageous for an aircraft manufacturer to be able to offer a wide range of aircraft configurations, with each configuration being tailored to a particular mission. In this way, customers desiring long-range aircraft could order models having relatively large fuel capacities and large wings, and customers desiring short-range aircraft could order models having relatively small fuel capacities and small wings. In practice, however, the cost associated with designing, manufacturing, and certifying a new aircraft is substantial. As a result, many aircraft manufacturers offer only a limited range of models that, not surprisingly, represent a compromise of disparate mission requirements.
One way that aircraft manufacturers try to minimize the high cost associated with developing new aircraft is to develop “derivative” aircraft. Derivative aircraft are “new” aircraft designs derived from existing aircraft designs. By utilizing many of the components and features from the existing aircraft designs, derivative aircraft can greatly reduce the cost of designing, manufacturing, and certifying a new aircraft configuration.
FIGS. 1A-C
are top views of three derivative aircraft wings
101
a-c
, respectively, in accordance with the prior art. Each of the derivative aircraft wings
101
a-c
provides more wing area than an existing wing
102
from which it was derived. For example, the derivative aircraft wing
101
a
shown in
FIG. 1A
includes the existing wing
102
and a wing-root insert
104
a
extending between the existing wing
102
and a fuselage
110
. The existing wing
102
includes an engine pod
142
and landing gear assembly
108
that are, accordingly, moved away from the fuselage
110
by the wing insert
104
a
. The derivative aircraft wing
101
b
shown in
FIG. 1B
includes a chordwise wing insert
104
b
extending between forward and aft portions of the existing wing
102
. The derivative aircraft wing
101
c
shown in
FIG. 1C
includes a wing-tip extension
104
c
extending outward from the existing wing
102
.
Each of the derivative aircraft wings
101
a-c
has shortcomings. For example, the wing-root insert
104
a
shown in
FIG. 1A
shifts the landing gear assembly
108
, the engine pod
142
, and other wing systems (e.g., leading edge slats, trailing edge flaps, and spoilers) away from the fuselage
110
, thus necessitating, at a minimum, lengthening of the fuel, hydraulic, and electrical lines that extend to these systems from the fuselage
110
. In addition, shifting the engine pod
142
further outboard can also require a redesign of the rudder of the baseline aircraft (not shown) to compensate for increased yaw forces resulting from an “engine out” design condition.
The chordwise insert
104
b
shown in
FIG. 1B
also has a number of shortcomings. For example, the addition of the chordwise insert
104
b
may require relofting the entire wing to restore the original airfoil shape of the existing wing
102
to the cross-section. In addition, the existing wing
102
must be reworked along the entire span to integrate the chordwise insert
104
b
with the existing structure.
The wing-tip extension
104
c
shown in
FIG. 1C
also has shortcomings. Although this may be the simplest approach to increasing wing area, the wing-tip extension
104
c
unfavorably shifts the center of pressure on the wing outboard, thereby increasing the bending loads on the existing wing
102
. As a result, adding the wing-tip extension
104
c
can require structurally reinforcing the existing wing
102
, especially at the attachment to the fuselage
110
. A further shortcoming associated with the wing-tip extension
104
c
is that structural reinforcement is often required at the tip of the existing wing
102
to carry the loads introduced from the wing-tip extension
104
c
. Still further, the wing-tip extension
104
c
typically does not provide a substantial increase in wing area or fuel volume.
SUMMARY
The present invention is directed to derivative aircraft and methods for their manufacture. In one embodiment, a derivative wing is derived from a baseline wing having a first outboard wing portion, a first forward inboard wing portion, and a first aft inboard wing portion. In one aspect of this embodiment, the derivative wing includes a second outboard wing portion sized and shaped at least generally similarly to the first outboard wing portion, a second forward inboard wing portion sized and shaped at least generally similarly to the first forward inboard wing portion, and a second aft inboard wing portion sized and shaped at least generally similarly to the first aft inboard wing portion. In another aspect of this embodiment, the derivative wing further includes a wing insert having a spanwise wing insert portion and a chordwise wing insert portion. In this embodiment, the chordwise wing insert portion is interposed between the second forward inboard wing portion and the second aft inboard wing portion to structurally connect the second forward inboard wing portion to the second aft inboard wing portion. Further, the spanwise wing insert portion is interposed between the second outboard wing portion and the second forward and aft inboard wing portions to structurally connect the second outboard wing portion to the second forward and aft inboard wing portions. Accordingly, in this embodiment, the addition of the wing insert portions provides the derivative wing with a wing area greater than the baseline wing from which it was derived. In other embodiments, wing portions similar to the wing insert portions can be removed from a baseline wing to provide a derivative wing with a wing area less than the baseline wing from which it was derived.
In another embodiment, a method for manufacturing an aircraft wing includes providing an outboard wing portion, a forward inboard wing portion, and an aft inboard wing portion. In one aspect of this embodiment, the aft inboard wing portion is configured to be attached to the forward inboard wing portion, and the outboard wing portion is configured to be attached to the forward and aft inboard wing portions. In another aspect of this embodiment, the method further includes attaching a chordwise wing insert portion to the forward and aft inboard wing portions, and attaching a spanwise wing insert portion to the outboard wing portion and the forward and aft inboard wing portions.
In yet another embodiment, a wing insert is usable with a baseline wing having an outboard wing portion and an inboard wing portion, the inboard wing portion having a forward inboard wing portion and an aft inboard wing portion. In one aspect of this embodiment, the wing insert includes a chordwise wing insert portion and a spanwise wing insert portion adjacent to the chordwise wing insert portion. The chordwise wing insert portion is configured to be interposed between the forward inboard wing portion and the aft inboard wing portion to increase an average chord of t
Dinh Tien
Perkins Coie LLP
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