Aeronautics and astronautics – Aircraft structure – Airfoil construction
Reexamination Certificate
2002-06-28
2004-08-24
Carone, Michael J. (Department: 3641)
Aeronautics and astronautics
Aircraft structure
Airfoil construction
C244S133000, C244S158700, C428S297400
Reexamination Certificate
active
06779757
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to preforms for use in construction of vehicles and relates specifically to preforms used for forming acute structural edges.
2. Description of the Related Art
When constructing vehicles, it is often desirable or necessary to create edges formed using acute angles. This is especially true when constructing air vehicles, such as manned or unmanned aircraft and missiles, which may require a sharpened edge for smoothly penetrating the airflow or providing a smooth convergence of separate flows.
FIG. 1
shows a prior art aircraft
11
and illustrates the numerous locations of acute structural edges. The most common use of acute edges is in leading edges
13
,
15
and trailing edges
17
,
19
of wings
21
,
23
, respectively. Leading edges
13
,
15
ensure that wings
21
,
23
pass easily through a longitudinal airflow, whereas trailing edges
17
,
19
allow the separated airflows on either side of wings
21
,
23
to smoothly converge at the rear of wings
21
,
23
. Inlet lips
25
separate onrushing air into flows entering engine nacelles
27
and flows continuing on the outer surfaces of aircraft
11
. Chines
29
are formed along longitudinal edges, providing desired aerodynamic effects and a blended shape for reducing radar cross-section.
FIGS. 2 through 4
illustrate prior art methods for forming acute structural edges. Though described in terms of directions relative to their orientation in the figures in the present application, it should be noted that the edges may be located in various orientations, including orientations opposite of those shown or in inclined or vertical orientations.
In
FIG. 2
, assembly
31
is formed by inserting a rigid edge member
33
between an upper planar element
35
and a lower planar element
37
. Edge member
33
and elements
35
,
37
may be formed from various materials, including metals and composites. When assembled, upper surface
39
of edge member
33
registers with the outer surface of element
35
and lower surface
41
registers with lower element
37
, forming smooth, continuous outer surfaces for undisturbed airflow. A forward edge
43
has an acute included angle and is located on the forward portion of edge member
33
. Members
45
extend from a rearward portion of edge member
33
for fastening edge member
33
to elements
35
,
37
. Members
45
are inwardly offset toward a plane (not shown) bisecting edge member
33
and parallel to forward edge
43
, forming rearward-facing shoulders
47
. The forward ends of elements
35
,
37
abut shoulders
47
. Typical methods of fastening edge member
33
to elements
35
,
37
include adhering members
45
to the inner surfaces of elements
35
,
37
and mechanically fastening members
45
to elements
35
,
37
.
FIG. 3
shows assembly
49
, which is formed by assembling upper element
51
with lower element
53
, elements
51
,
53
being formed of rigid materials, such as metals or composites. Elements
51
,
53
terminate in forward ends
55
,
57
, respectively, each forward end
55
,
57
having an increased thickness and mating surface. When elements
51
,
53
are assembled to each other, the mating surfaces are adjacent at seam
59
and forward ends
55
,
57
are aligned to form forward edge
61
. Elements
51
,
53
are fastened together at forward ends
55
,
57
by fastener
63
, for example, a double-countersunk fastener, which extends through the thickness of the assembled forward ends
55
,
57
.
Like assembly
49
in
FIG. 3
, edge assembly
65
in
FIG. 4
comprises upper element
67
and lower element
69
. Upper element
67
has a forward end
71
having an increased thickness and a downward-facing mating surface. Lower element
69
has a forward end
73
that also has an increased thickness and an upward-facing mating surface. Elements
67
,
69
are aligned and joined to each other, the mating surfaces being adjacent at seam
75
and forward ends
71
,
73
aligning to form forward edge
77
. Rather than being joined using fasteners, elements
67
,
69
adhered to each other or bonded in a co-curing process.
While these prior art assemblies have satisfactorily been used to form acute edge structures, improvements are needed to reduce weight and cost and increase structural integrity of edge structures. Additionally, improvements are needed to improve the ability to repair damaged edge structures and to allow for tailored material and structural properties.
BRIEF SUMMARY OF THE INVENTION
An apparatus and method are provided for constructing acute structural edges. A preform has a body having an acute-angle edge at one end and connecting areas extending from the opposing end for bonding the preform to converging planar elements of a wing or other similar structure. In several embodiments, the acute angle of the preform generally matches the angle relative to each other of converging ends of the planar elements, the preform forming the outer end of smooth, continuous outer surfaces after assembly. The connecting areas may be connected to interior or exterior surfaces of the elements, depending on the orientation of the preform and elements. In another embodiment, the preform is placed between the outer ends of the elements for aligning and supporting the elements at the desired location and angle relative to each other.
REFERENCES:
patent: 3637325 (1972-01-01), Morley
patent: 3779487 (1973-12-01), Ashton et al.
patent: 4051289 (1977-09-01), Adamson
patent: 4095322 (1978-06-01), Scarpati et al.
patent: 4284443 (1981-08-01), Hilton
patent: 4565595 (1986-01-01), Whitener
patent: 4657615 (1987-04-01), Braun et al.
patent: 4693435 (1987-09-01), Percival et al.
patent: 5248242 (1993-09-01), Lallo et al.
patent: 5395691 (1995-03-01), Kavesh et al.
patent: 5616391 (1997-04-01), Amesz et al.
patent: 5965240 (1999-10-01), Blackburn et al.
patent: 12 14 092 (1966-04-01), None
Bracewell & Patterson L.L.P.
Carone Michael J.
Lockheed Martin Corporation
Sukman Gabriel S
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