U.S. patent application number 14/686052 was filed with the patent office on 2016-06-16 for collapsible wing and unmanned aircraft systems including collapsible wing.
The applicant listed for this patent is CAWTU, LLC. Invention is credited to James Emmett Dee Barbieri.
Application Number | 20160167765 14/686052 |
Document ID | / |
Family ID | 52822463 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160167765 |
Kind Code |
A1 |
Barbieri; James Emmett Dee |
June 16, 2016 |
COLLAPSIBLE WING AND UNMANNED AIRCRAFT SYSTEMS INCLUDING
COLLAPSIBLE WING
Abstract
A collapsible wing, methods of producing the collapsible wing,
and an unmanned aircraft system that includes the collapsible wing
are provided.
Inventors: |
Barbieri; James Emmett Dee;
(Richmond Heights, MO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CAWTU, LLC |
Clayton |
MO |
US |
|
|
Family ID: |
52822463 |
Appl. No.: |
14/686052 |
Filed: |
April 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13463516 |
May 3, 2012 |
9010693 |
|
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14686052 |
|
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|
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61482079 |
May 3, 2011 |
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Current U.S.
Class: |
244/46 ;
244/213 |
Current CPC
Class: |
B64C 3/54 20130101; B64C
39/024 20130101; Y02T 50/10 20130101; B64C 2201/203 20130101; Y02T
50/14 20130101; B64C 2201/102 20130101; B64C 2201/021 20130101;
B64C 3/56 20130101 |
International
Class: |
B64C 3/56 20060101
B64C003/56; B64C 39/02 20060101 B64C039/02 |
Claims
1-8. (canceled)
9. A collapsible wing for an unmanned aircraft system, the wing
comprising at least two monocoque wing sections comprising a wing
root section, a wing span section, a wing tip section, and a wing
tip end plate or a winglet attached to the wing tip section,
wherein: the wing is configured to deploy between a collapsed
configuration and an extended configuration; the wing span section
nests within a lumen of the wing root section and the wing tip
section nests within a lumen of the wing span section in the
collapsed configuration; at least a portion of the wing span
section protrudes from within the lumen of the wing root section
and at least a portion of the wing tip section protrudes from
within the lumen of the wing span section in the extended
configuration; and the wing tip section further comprises a
connector and the wing tip end plate or the winglet further
comprises a mating connector, wherein: the wing tip end plate or
the winglet is removed from the wing tip section when the wing is
in the collapsed configuration; and the wing tip end plate or the
winglet is attached to the wing tip section by mating the connector
and the mating connector when the wing is in the extended
configuration.
10. The collapsible wing according to claim 9, wherein the wing tip
section further comprises a grip to facilitate the deployment of
the wing, the grip chosen from any one or more of: a strap, a
handle, an indented lip, or a gripping structure to facilitate the
deployment and collapsing of the wing.
11. The collapsible wing according to claim 9, further comprising
one or more movable control surfaces, wherein the one or more
movable control surfaces consists of an aileron, a flap, or a flap
and an aileron.
12. The collapsible wing according to claim 11, wherein any one or
more of the at least two wing sections integrates each of the one
or more movable control surfaces.
13. The collapsible wing according to claim 11, wherein each
movable control surface further comprises a connector and each
corresponding wing section further comprises a mating connector,
wherein: each movable control surface is removed from the
corresponding wing section when the wing is in the collapsed
configuration; and each movable control surface is attached to the
corresponding wing section by mating the connector and the mating
connector when the wing is in the extended configuration.
14. The collapsible wing according to claim 11, further comprising
one or more actuators situated within any one or more of the at
least two wing sections, wherein the one or more actuators
effectuate movement of the one or more movable control
surfaces.
15. The collapsible wing according to claim 14, further comprising
at least one additional transmissive element chosen from one or
more of: electrical wires, cables, or optical fibers, the at least
one additional transmissive element situated within any one or more
of the at least two wing sections to transmit any one or more of
power, control command signals, sensor signals, and any combination
thereof.
16. A collapsible wing for an unmanned aircraft system, the wing
comprising at least two monocoque wing sections comprising a wing
root section, and a wing span section, wherein: the wing is
configured to deploy between a collapsed configuration and an
extended configuration; the wing span section nests within a lumen
of the wing root section in the collapsed configuration; at least a
portion of the wing span section protrudes from within the lumen of
the wing root section in the extended configuration; and each wing
section comprises a taper comprising an outboard chord length at an
outboard edge of the wing section shorter than an inboard chord
length at an inboard edge of the wing section.
17. The collapsible wing according to claim 16, wherein the taper
of each wing section mechanically limits the protrusion of each
wing section to prevent separation of adjacent wing sections during
deployment to the extended configuration.
18. (canceled)
19. A collapsible wing for an unmanned aircraft system, the wing
comprising at least two monocoque wing sections comprising a wing
root section, and a wing span section, wherein: the wing is
configured to deploy between a collapsed configuration and an
extended configuration; the wing span section nests within a lumen
of the wing root section in the collapsed configuration; at least a
portion of the wing span section protrudes from within the lumen of
the wing root section in the extended configuration; the wing
further comprises at least one overlap region when the wing is in
the extended configuration, each overlap region comprising a nested
portion of a protruding wing section remaining within the lumen of
an adjacent wing section with a degree of overlap comprising a
separation distance between the inboard edge of the protruding wing
section and the outboard edge of the adjacent wing section; and a
first degree of overlap between the wing root section and the
protruding wing span section is larger than a second degree of
overlap between the wing span section and the protruding wing tip
section.
20-22. (canceled)
23. A collapsible wing for an unmanned aircraft system, the wing
comprising at least two monocoque wing sections comprising a wing
root section, and a wing span section, wherein: the wing is
configured to deploy between a collapsed configuration and an
extended configuration; the wing span section nests within a lumen
of the wing root section in the collapsed configuration; at least a
portion of the wing span section protrudes from within the lumen of
the wing root section in the extended configuration; and each
outboard edge of each wing section further comprises an outboard
edge profile forming a gradual transition in thickness from an
exposed surface of the protruding wing section to an exposed
surface of the adjacent wing section, the outboard edge profile
comprising: a flat ramp, a rounded corner, a series of smaller
steps, and any combination thereof.
24. A collapsible wing for an unmanned aircraft system, the wing
comprising at least two monocoque wing sections comprising a wing
root section, and a wing span section, wherein: the wing is
configured to deploy between a collapsed configuration and an
extended configuration; the wing span section nests within a lumen
of the wing root section in the collapsed configuration; at least a
portion of the wing span section protrudes from within the lumen of
the wing root section in the extended configuration; and the wing
further comprises a covering situated over the at least two wing
sections in the extended configuration, wherein the covering forms
a smooth, seamless wing surface.
25. (canceled)
26. The collapsible wing according to claim 16, further comprising
one or more movable control surfaces, wherein the one or more
movable control surfaces consists of an aileron, a flap, or a flap
and an aileron.
27. The collapsible wing according to claim 26, wherein any one or
more of the at least two wing sections integrates each of the one
or more movable control surfaces.
28. The collapsible wing according to claim 26, wherein each
movable control surface further comprises a connector and each
corresponding wing section further comprises a mating connector,
wherein: each movable control surface is removed from the
corresponding wing section when the wing is in the collapsed
configuration; and each movable control surface is attached to the
corresponding wing section by mating the connector and the mating
connector when the wing is in the extended configuration.
29. The collapsible wing according to claim 26, further comprising
one or more actuators situated within any one or more of the at
least two wing sections, wherein the one or more actuators
effectuate movement of the one or more movable control
surfaces.
30. The collapsible wing according to claim 26, further comprising
at least one additional transmissive element chosen from one or
more of: electrical wires, cables, or optical fibers, the at least
one additional transmissive element situated within any one or more
of the at least two wing sections to transmit any one or more of
power, control command signals, sensor signals, and any combination
thereof.
31. The collapsible wing according to claim 19, further comprising
one or more movable control surfaces, wherein: the one or more
movable control surfaces consist of an aileron, a flap, or a flap
and an aileron; and any one or more of the at least two wing
sections integrates each of the one or more movable control
surfaces.
32. The collapsible wing according to claim 31, further comprising:
one or more actuators situated within any one or more of the at
least two wing sections, wherein the one or more actuators
effectuate movement of the one or more movable control surfaces;
and at least one additional transmissive element chosen from one or
more of: electrical wires, cables, or optical fibers, the at least
one additional transmissive element situated within any one or more
of the at least two wing sections to transmit any one or more of
power, control command signals, sensor signals, and any combination
thereof.
33. The collapsible wing according to claim 23, further comprising
one or more movable control surfaces, wherein: the one or more
movable control surfaces consist of an aileron, a flap, or a flap
and an aileron; and any one or more of the at least two wing
sections integrates each of the one or more movable control
surfaces.
34. The collapsible wing according to claim 33, further comprising:
one or more actuators situated within any one or more of the at
least two wing sections, wherein the one or more actuators
effectuate movement of the one or more movable control surfaces;
and at least one additional transmissive element chosen from one or
more of: electrical wires, cables, or optical fibers, the at least
one additional transmissive element situated within any one or more
of the at least two wing sections to transmit any one or more of
power, control command signals, sensor signals, and any combination
thereof.
35. The collapsible wing according to claim 34, wherein each
movable control surface further comprises a connector and each
corresponding wing section further comprises a mating connector,
wherein: each movable control surface is removed from the
corresponding wing section when the wing is in the collapsed
configuration; and each movable control surface is attached to the
corresponding wing section by mating the connector and the mating
connector when the wing is in the extended configuration.
36. The collapsible wing according to claim 24, further comprising
one or more movable control surfaces, wherein: the one or more
movable control surfaces consist of an aileron, a flap, or a flap
and an aileron; and any one or more of the at least two wing
sections integrates each of the one or more movable control
surfaces.
37. The collapsible wing according to claim 36, further comprising:
one or more actuators situated within any one or more of the at
least two wing sections, wherein the one or more actuators
effectuate movement of the one or more movable control surfaces;
and at least one additional transmissive element chosen from one or
more of: electrical wires, cables, or optical fibers, the at least
one additional transmissive element situated within any one or more
of the at least two wing sections to transmit any one or more of
power, control command signals, sensor signals, and any combination
thereof.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of prior U.S. application
Ser. No. 13/463,516, filed May 5, 2012, which is hereby
incorporated by reference herein in its entirety. Prior U.S.
application Ser. No. 13/463,516 claims the benefit of U.S.
Provisional Application No. 61/482,079, filed on May 3, 2011, which
is hereby incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] This application relates to a collapsible wing, methods of
producing the collapsible wing, and an unmanned aircraft system
that includes a collapsible wing.
BACKGROUND OF THE INVENTION
[0003] In modern-day military operations, unmanned aircraft systems
(UAS) may be carried by front-line soldiers for use as a quick
source of intelligence as needed. In those areas of interest which
are too dangerous for humans to investigate first-hand, a UAS may
be assembled and launched to observe the area of conflict using an
array of intelligence, surveillance, and reconnaissance (ISR)
sensors carried by the UAS airframe. Imaging sensors may typically
include electro-optic (EO), infrared (IR), and synthetic aperture
radar (SAR). Emerging uses of UAS may include integrated signals
intelligence (SIGINT), electronic warfare (EW), cyber warfare, data
relay, and attack capabilities. Existing UAS airframes are
typically radio-controlled aircraft with varying levels of
autonomous flight capabilities. Small class UAS may typically have
wingspans ranging between about four and about five feet.
[0004] Mobility and ease of use are somewhat limited for existing
UAS. Existing UAS are typically transported in a disassembled state
with the wing detached from the fuselage of the aircraft.
Transporting an existing UAS aircraft in the field typically
entails carrying multiple boxes that are the full size of the wing,
and may require two or more personnel to move. Further, the
assembly of some existing UAS aircraft may be accomplished with
tools that may be difficult to operate in limited visibility
conditions or by soldiers wearing protective gear such as gas masks
or gloves.
[0005] The limited mobility and difficulty of assembly in certain
conditions may hamper the effectiveness of UAS by front-line
soldiers in combat situations. The bulky crates may hamper the
mobility of the soldiers and limit the front-line scenarios in
which an UAS may be used. If the assembly of the UAS in the field
requires an inordinate amount of time to unpack, assemble, and/or
deploy, the resulting delay in obtaining critical intelligence may
squander a window of opportunity to complete a mission or
potentially endanger the lives of personnel.
[0006] In addition, the role of UAS technology is expanding to
encompass a wide variety of operational scenarios including law
enforcement, border patrol, search and rescue, mapping, meteorology
and other scientific research, as well as recreational uses. At
present, the U.S. Federal Aviation Administration (FAA) is
considering the release of formal regulations related to the
operation of small, unmanned air vehicles (UAVs) within U.S.
airspace. Given the proliferation of these UAVs, there exists a
need for a fundamental improvement of their design to increase
portability, usability, and practicality.
[0007] A need exists in the art for a UAS with enhanced mobility
and ease of assembly. In particular, a need in the art exists for a
UAS that may be transported in a container small enough to be
easily carried by an individual operator. Further, a need in the
art exists for an easily transported UAS that may be assembled
quickly in low visibility and time-sensitive conditions without the
use of tools or extensive training. Such a UAS may facilitate the
continued adoption of UAS by a larger number of users in a wider
variety of scenarios.
SUMMARY OF INVENTION
[0008] In an aspect, a collapsible wing for an unmanned aircraft
system is provided that includes a central section attachable to a
fuselage of the unmanned aircraft system and a plurality of
monocoque wing sections. The plurality of wing sections may include
at least two left wing sections that include a left wing root
section and a left wing span section. The left wing span section
may nest within the left wing root section and the left wing root
section may nest within the central section when the wing is in a
collapsed configuration. The plurality of wing sections may further
include at least two right wing sections that include a right wing
root section and a right wing span section. The right wing span
section may nest within the right wing root section and the right
wing root section may nest within the central section opposite to
the left wing root section when the wing is in the collapsed
configuration. The wing may be configured to be deployed between
the collapsed configuration and an extended configuration. The
extended configuration may include: at least a portion of the left
wing span section protruding from within the left wing root
section; at least a portion of the left wing root section
protruding from within the central section; at least a portion of
the right wing span section protruding from within the right wing
root section; and at least a portion of the right wing root section
protruding from within the central section. The plurality of wing
sections may further include any one or more of: metals, metal
alloys, plastics, woods, composite materials, and any combination
thereof. The plurality of wing sections may be strutless. The
central section may further include an attachment fitting
configured to engage a corresponding receptacle formed in a
fuselage of the unmanned aircraft system
[0009] In another aspect, a collapsible wing for an unmanned
aircraft system is provided that includes at least two monocoque
wing sections. The at least two monocoque wing sections may include
a wing root section and a wing span section. The wing may be
configured to deploy between a collapsed configuration and an
extended configuration. The wing span section may be nested within
a lumen of the wing root section in the collapsed configuration. At
least a portion of the wing span section may protrude from within
the lumen of the wing root section in the extended configuration.
The wing may further include at least one overlap region when the
wing is in the extended configuration. Each overlap region may
include a nested portion of a protruding wing section remaining
within the lumen of an adjacent wing section with a degree of
overlap including a separation distance between the inboard edge of
the protruding wing section and the outboard edge of the adjacent
wing section. The at least two wing sections may further include a
wing tip section. The wing tip section may nest within a lumen of
the wing span section in the collapsed configuration, and at least
a portion of the wing tip section may protrude from within the
lumen of the wing span section in the extended configuration. The
collapsible wing may further include a wing tip end plate or a
winglet attached to the wing tip section. The wing tip section may
further include a connector and the wing tip end plate or the
winglet may further include a mating connector. The wing tip end
plate or the winglet may be removed from the wing tip section when
the wing is in the collapsed configuration; and the wing tip end
plate or the winglet may be attached to the wing tip section by
mating the connector and the mating connector when the wing is in
the extended configuration. The wing tip section may further
include a grip to facilitate the deployment of the wing. The grip
may be chosen from any one or more of: a strap, a handle, an
indented lip, or a gripping structure to facilitate the deployment
and collapsing of the wing. The wing may further include one or
more movable control surfaces consisting of an aileron, a flap, or
a flap and an aileron. The any one or more of the at least two wing
sections may integrates each of the one or more movable control
surfaces. Each movable control surface may further include a
connector and each corresponding wing section may further include a
mating connector. Each movable control surface may be removed from
the corresponding wing section when the wing is in the collapsed
configuration; and each movable control surface may be attached to
the corresponding wing section by mating the connector and the
mating connector when the wing is in the extended configuration.
The wing may further include one or more actuators situated within
any one or more of the at least two wing sections to effectuate
movement of the one or more movable control surfaces. The wing may
further include at least one additional transmissive element chosen
from one or more of: electrical wires, cables, or optical fibers,
the at least one additional transmissive element situated within
any one or more of the at least two wing sections to transmit any
one or more of power, control command signals, sensor signals, and
any combination thereof. Each wing section may include a taper that
includes an outboard chord length at an outboard edge of the wing
section shorter than an inboard chord length at an inboard edge of
the wing section. The taper of each wing section may mechanically
limit the protrusion of each wing section to prevent separation of
adjacent wing sections during deployment to the extended
configuration. All degrees of overlap may be equal to one another,
or a first degree of overlap between the wing root section and the
protruding wing span section may be larger than a second degree of
overlap between the wing span section and the protruding wing tip
section. The wing may further include one or more locking elements
situated within the at least one overlap region to reversibly
secure adjacent wing sections in the extended configuration. A
first portion of the one or more locking elements situated within
one overlap region may be spatially staggered with respect to other
locking elements situated within other overlap regions. Each of the
at least two wing sections may include a thin membrane formed into
an airfoil cross-sectional shape surrounding the lumen. Each thin
membrane of each wing section may include any one or more of:
metals, metal alloys, plastics, woods, composite materials, and any
combination thereof. Each thin membrane of each wing section may
include a membrane thickness characterized by one of: all thin
membranes of all wing sections have a uniform membrane thickness;
each membrane thickness of each wing section is different from each
other wing section; or each membrane thickness varies within each
wing section. Each outboard edge of each wing section may further
include an outboard edge profile forming a gradual transition in
thickness from an exposed surface of the protruding wing section to
an exposed surface of the adjacent wing section, the outboard edge
profile comprising: a flat ramp, a rounded corner, a series of
smaller steps, and any combination thereof. The wing may further
include a covering situated over the at least two wing sections in
the extended configuration to form a smooth, seamless wing surface.
The wing may further include an additional mechanical element to
aid in the deployment and collapse of the wing. The additional
mechanical element may include one or more of: cables, pulleys,
pushrods, screwjacks, and any combination thereof.
[0010] Other aspects and iterations of the disclosure are described
in detail below.
DESCRIPTION OF FIGURES
[0011] The following figures illustrate various aspects of the
embodiments:
[0012] FIG. 1 is a chordwise side view of a collapsible wing in a
collapsed position.
[0013] FIG. 2 is a top view of a collapsible wing in an extended
position.
[0014] FIG. 3 is a top view of a full-span collapsible wing in an
extended position.
[0015] FIG. 4A is a top cross-sectional view of an interlocking
flange locking mechanism for a collapsible wing in the collapsed
configuration.
[0016] FIG. 4B is a top cross-sectional view of an interlocking
flange locking mechanism for a collapsible wing in the extended
configuration.
[0017] FIG. 5 is a front cross-sectional view of a locking
mechanism for a collapsible wing that includes frictional linings
on the contacting surfaces of adjacent wing sections.
[0018] FIG. 6 is a front cross-sectional view of a locking
mechanism for a collapsible wing that includes paired magnets
imbedded in adjacent wing sections.
[0019] FIG. 7 is an illustration of an airfoil profile suitable for
use in a collapsible wing.
[0020] FIG. 8 is an illustration of the orientation of the
composite layers used to construct a collapsible wing in an
embodiment.
[0021] FIGS. 9A and 9B are illustrations of a movable surface
including a collapsible wing in an undeflected (FIG. 9A) and
deflected (FIG. 9B) positions.
[0022] FIG. 10 is a photograph of the wing tip section during a
vacuum curing process after carbon fiber lay up.
[0023] FIG. 11 is a photograph of the cured wing span sections
before separation.
[0024] FIG. 12 is a photograph showing the separation of cured wing
sections from the wing tip mold and adjacent wing span
sections.
[0025] FIG. 13 is a photograph of a prototype collapsible wing in a
collapsed position.
[0026] FIG. 14 is a photograph showing a prototype collapsible wing
in an extended position.
[0027] Corresponding reference characters indicate corresponding
elements among the views of the drawings. Any headings or labels
used in the figures should not be interpreted to limit the scope of
the claims.
DETAILED DESCRIPTION
[0028] Various aspects provide a collapsible wing, aircraft and
systems that include the collapsible wings, methods of producing
the collapsible wings, and methods of using the collapsible wings.
The collapsible wings include at least two wing span sections that
may be stored in a collapsed configuration in which a smaller wing
span section is nested inside a spanwise lumen within a larger
adjoining wing span section. To deploy the wings in an extended
configuration, the smallest wing span section, typically the wing
tip section, is deployed in an outboard direction away from the
other nested wing span sections, resulting in an outboard sliding
movement of each wing span section relative to its corresponding
larger adjacent wing span section, culminating in a fully extended
wing in an extended configuration. The collapsible wing may be
extended and collapsed by a single person without need for
specialized tools.
[0029] Each of the collapsible wings in the collapsed configuration
may be packed for transport within a container or backpack with
dimensions corresponding to the wing's longest chord length, the
span length of the wing's largest wing span section, and the
maximum thickness of the wing. For example, in the collapsed
configuration, the collapsible wing may fit within a volume with
dimensions of about one foot by one foot by a few inches in one
aspect. Further, each collapsible wing may have a relatively low
weight due to the use of light-weight, high-strength composite
materials. The compact size of the collapsible wings in a collapsed
state, combined with each wing's low weight and ease of assembly,
result in a wing structure that is ideally suited for portable
aircraft applications such as unmanned aircraft systems (UAS) that
may be carried and deployed by personnel in remote locations in a
relatively short time without need for specialized training or
tools.
[0030] A detailed description of aspects of the collapsible wing
design, methods of fabricating the collapsible wing, UAS and
associated air vehicles that incorporate the collapsible wing, and
methods of using the collapsible wing in air vehicles such as the
air vehicles of an UAS are described in detail herein below.
[0031] I. Collapsible Wing
[0032] In one aspect, a collapsible wing is provided that includes
a series of wing sections that may be nested within one another in
a collapsed configuration. In the collapsed configuration, the
collapsible wing not only achieves minimal size for ready
transportation in existing backpacks typically used by personnel in
remote operations, but the nested arrangement of wing span sections
offers enhanced protection of the wing span sections from physical
damage during transport. To convert the collapsed wing to a
functional extended wing configuration, the wing sections may be
translated relative to one another by deploying the outermost wing
tip section in an outboard, resulting in a telescope-like movement
of the wing sections into an extended configuration. The wing
sections may be secured in the extended configuration using a
locking mechanism, described in detail herein below.
A. Collapsed Configuration
[0033] A side view of a collapsible wing 100 in the collapsed
configuration is illustrated in FIG. 1. In general, the collapsible
wing 100 includes at least one wing span section nested within a
second wing span section. In an aspect, the nested wing span
sections may include a wing root section 102 and a wing tip section
110. For purposes of illustration, five nested wing span sections
102-110 are illustrated in FIG. 1. Each of the wing span sections
102-110 is formed from a thin membrane in an airfoil
cross-sectional shape as shown in FIG. 1. In addition, the thin
membrane of each wing span section 102, 104, 106, 108 defines a
lumen 112, 114, 116, and 118, respectively. Each of the lumens
112-118 extends the full spanwise length of each of the wing span
sections 102-108. In addition, each of the lumens 112-118 opens at
both the inboard and outboard ends of each of the wing span
sections 102-108. The thin membrane of the wing tip section 110
defines a lumen 120 that extends the full span of the wing tip
section 110 and opens at the section's inboard end; the lumen 120
may sealed at the outboard tip of the wing tip section 110.
[0034] The outboard tip of the wing tip section 110 may further
include additional structures or elements (not shown) to facilitate
the deployment and collapsing of the wing. In an aspect, the
outboard tip of the wing tip section 110 may further include a
strap, a handle, or an indented lip to provide a grip used by the
operator of the UAS when moving the wing tip inboard or outboard.
In another aspect, the wing tip section 110 may further include
additional aerodynamic surfaces including, but not limited to, wing
tip end plates, winglets, and/or moveable control surfaces; these
additional aerodynamic surfaces may enhance the overall aerodynamic
performance of the UAS in use. In additional aspects, the
additional aerodynamic surfaces may be integrated into the
structure of the wing tip section 110 or the additional aerodynamic
surfaces may be provided as separate structures that are attached
to the wing tip section 110 during deployment of the wing by way of
mating connectors integrated into the structure of the wing tip
section 110 and additional aerodynamic surface.
[0035] As illustrated in FIG. 1, when the wing 100 is in the
collapsed configuration, the wing tip section 110 is nested within
the lumen 118 of wing span section 108, the wing span section 108
is nested within the lumen 116 of wing span section 106, the wing
span section 106 is nested within the lumen 114 of wing span
section 104, and the wing span section 104 is nested within the
lumen 112 of wing span section 102. In general, the collapsible
wing 100 may include any size and number of wing span sections
without limitation; design considerations related to the selection
of the size and number of wing span sections are described in
detail herein below.
B. Extended Configuration
[0036] The collapsible wing 100 may be transformed reversibly from
a collapsed configuration to an extended configuration by
externally pulling the wing tip section 110 in an outboard
direction, causing each of the wing span sections 104-110 to
translate in an outboard direction relative to each corresponding
adjacent wing span section. As illustrated FIG. 2, when the wing
tip section 110 is moved in an outboard direction, the wing tip
section 110 translates outboard relative to its adjacent wing span
section 108, the wing span section 108 translates outboard relative
to its adjacent wing span section 106, the wing span section 106
translates outboard relative to its adjacent wing span section 104,
and the wing span section 104 translates outboard relative to its
adjacent wing span section 102.
[0037] In an aspect, each of the wing span sections 102-110 may
incorporate one or more mechanical limits designed to prevent the
overextension and/or separation of adjacent wing span sections
during deployment. In one aspect, shown in FIG. 2, the chord length
at the outboard edge of each wing span section may taper to a
shorter length than the corresponding chord length at the inboard
edge. For example, as result of this taper, the chord length at the
inboard edge 214 of wing span section 104 may be larger than the
size of the opening of the lumen 112 of the adjacent wing span
section 102 at its outboard edge 216. This size difference
mechanically limits the outboard translation of the wing span
section 104, preventing the separation of this section during
deployment.
[0038] In another aspect, shown in FIG. 4A, the collapsible wing
100 may include interlocking flanges 406 and 408 on the inboard end
of a first wing span section 402 and flanges 410 and 412 on the
outboard end of a second wing span section 404. The collapsible
wing 100 in this aspect is illustrated in a collapsed configuration
in FIG. 4A. When the first wing span section 402 is moved in an
outboard direction to deploy the wing 100, as shown in FIG. 4B, the
interlocking flanges 406 and 408 mechanically lock with
interlocking flanges 410 and 412, respectively, preventing the
overextension and separation of the first wing span section 402
from the second wing span section 404. The interlocking flanges
406, 408, 410, and 412 may further define a pre-specified extension
limit for the collapsible wing 100 in the extended
configuration.
[0039] The amount of force applied to the wing tip section 110 in
order to deploy the wing span sections 102-110 may be specified
such that a single person may deploy the wing span sections
102-110. The wing root section 102 may be maintained in a
relatively fixed position to facilitate the transformation of the
wing 100 into an extended configuration. For example, the wing root
section 102 may be attached to the fuselage of an air vehicle as
described herein below prior to deploying the wing 100 into the
extended configuration, or the wing root section 102 may be held in
a fixed position by a second person during deployment. In another
example, the wing root section 102 may be pulled in an inboard
direction opposite to the outboard movement of the wing tip section
110.
[0040] In another aspect, the wing 100 may be deployed by
gravitational forces induced by pointing the wing in a downward
direction and allowing the wing tip section to slide downward along
with any other wing span sections. In yet another aspect, the wing
100 may incorporate mechanical elements including, but not limited
to, cables and/or pulleys, pushrods, screwjacks, and any other
suitable mechanical element known in the art, to provide an
enhanced mechanical advantage to a person deploying the wing 100,
or to direct an applied force into a direction suitable for wing
deployment.
[0041] A top (planform) view of the wing 100 in the extended
configuration is illustrated in FIG. 2. As viewed from above, the
wing span sections 102-110 may be rectangle-shaped, as illustrated
in FIG. 2. In an aspect, each wing span may be tapered such that
each wing span section has a shorter or longer chord length at the
outboard end relative to the inboard end of the wing span section.
In order to nest together efficiently in the collapsed
configuration, the taper of each wing span section may consistently
increase or decrease in the outboard spanwise direction in another
aspect. In an additional aspect, the planform shape of the wing
span sections 102-110 may be sized, tapered, and dimensioned such
that each wing span section 104-110 slips easily into the lumen
112-118 of each corresponding adjacent outboard wing span 102-108,
respectively. In this aspect, the selected airfoil or shape of the
root airfoil may change in subsequent outboard wing span sections
to facilitate proper movement of the wing span sections and to
ensure sufficient continuity of the wing span sections to meet the
design goals of the UAS.
[0042] In another aspect, the collapsible wing may extend the full
wingspan, rather than extending approximately half of the total
wing span (not including the width of the fuselage) as illustrated
in FIG. 2. FIG. 3 is an illustration of an aspect of a full-span
collapsible wing 100A shown in the extended configuration that
includes a central section 302 or cavity within a fuselage section,
left wing span sections 304-310 and right wing span sections
312-318. In the collapsed configuration, the left wing span
sections 304-310 nest within each other and the right wing span
sections 312-318 nest within each other in a similar manner to the
collapsible wing 100 shown in FIG. 1. In addition, the left wing
root section 304, which contains the nested left wing span sections
306-310, and the right wing root section 312, which contains nested
right wing span sections 314-318, are both nested within the lumen
of the central section 302. As a consequence, the spanwise
dimension of the central section 302 may be at least twice the
spanwise dimension of the left and right wing root sections 304 and
312 in order to completely nest these sections in the collapsed
configuration.
[0043] The full-span collapsible wing 100A may include interlocking
flange elements similar to those described previously for the
collapsible wing 100 to prevent the overextension and/or separation
of wing span sections during the deployment of the wing 100A. In an
additional aspect, the interlocking elements may be designed to be
deactivated in order to remove a subset of the wing 100A including,
but not limited to, the left wing or the right wing or any wing
span section thereof, in order to facilitate repair or replacement
of a damaged section of the full-span collapsible wing 100A.
[0044] To extend the full-span collapsible wing 100A from the
collapsed configuration to the extended configuration, the left and
right wing tips 310 and 318 may be deployed independently in
opposing outboard directions away from the central section 302. The
outboard forces applied to the left and right wing tips 310 and 318
induce the translation of adjacent wing sections 304-310 and
312-318 in an outboard direction relative to each other, resulting
in extension of all wing sections into the extended
configuration.
C. Number and Size of Wing Span Sections
[0045] Any number of wing span sections may be included in various
aspects of the collapsible wing 100. The number, length,
dimensions, thickness, and composition of the wing span sections
may be selected based on any one or more of at least several
factors including, but not limited to: the desired function of an
aircraft including the collapsible wing 100, the total wingspan of
the collapsible wing 100 in the extended configuration, the desired
wingspan of the collapsible wing 100 in the collapsed
configuration, the desired structural integrity of the extended
wing structure, the desired overall weight of the collapsible wing
100, and the size of the wing span sections making up the
collapsible wing 100, in particular the chord length and individual
wing span section lengths in the spanwise direction. In an aspect,
the collapsible wing 100 includes at least two wing span sections.
In another aspect, the collapsible wing 100 may include from about
two to about ten wing span sections.
[0046] In yet another aspect, the number of wing span sections may
be limited by the thickness of the material making up each wing
span section. Referring again to FIG. 1 and FIG. 2, each wing span
section must be smaller than its corresponding adjacent outboard
wing span section in order to nest within the lumen of the
corresponding adjacent outboard wing span section in the collapsed
configuration. As a result, each successive outboard wing span
section must be reduced in size in all dimensions in order to fit
within the lumen of its corresponding adjacent inboard wing span
section. The reduction in size of successive wing span sections may
depend on one or more of at least several factors including, but
not limited to: the thickness of the material making up each wing
span section, changes in the airfoil section between wing span
sections, the incorporation of additional elements such as
electrical wires, cables, or optical fibers within the lumens of
the wing span sections to transmit power, control commands, and/or
sensor signals within the air vehicle, and the particular locking
mechanism incorporated to secure the wing span sections in the
extended configuration.
[0047] The size of each of the wing span sections 102-110 may be
any size and may be specified by any one or more of at least
several factors including, but not limited to: the desired
performance of the collapsible wing in use; the overall size,
design, and mission of the air vehicle in which the collapsible
wing is incorporated; the portability of the collapsible wing in
the collapsed configuration; the desired structural integrity of
the collapsible wing in use; the number of wing span sections
included in the collapsible wing; and the thickness of the thin
membrane formed into the airfoil shape of each wing span
section.
[0048] In an aspect, if the collapsible wing is to be incorporated
into an air vehicle of an unmanned aircraft system, the overall
size and weight of the system in a disassembled state may be
reduced as much as possible, since both of these characteristics
contribute to the portability of the system and the weight of the
air vehicle. In the disassembled state of the air vehicle, the
collapsible wing is typically transported in a collapsed
configuration, in which the outboard wing span sections are nested
within the wing root section. As a result, the largest dimensions
of the collapsible wing in the collapsed configuration correspond
to the dimensions of the wing root section. For example, to enhance
portability the wing root section may be dimensioned such that the
collapsible wing may be transported in a typical backpack used by
personnel in remote operation. In this example, the maximum
dimensions of the wing span sections may be about 18 inches in the
spanwise and chordwise directions, and about 4 inches thick. In
another aspect, the maximum dimensions of the wing span sections
may be up to about 9 inches in the spanwise direction, up to about
6 inches in the chordwise direction, and up to about two inches in
thickness. The overall size of the wing in the collapsed
configuration can and will vary without limitation depending on the
particular design of the associated air vehicle.
D. Overlap Between Wing Span Sections
[0049] Referring again to FIG. 2, each of the wing span sections
104-110 in the extended configuration protrudes in an outboard
direction from a spanwise lumen 112-118, respectively, of a
corresponding adjacent wing span section 102-108, situated inboard
of each wing span section 104-110, and ending at the wing tip
section 110 in the most outboard position of the wing. Each of the
wing sections 104-110 typically does not protrude completely from
its respective lumen 112-118, respectively, resulting in an overlap
region 206-212, respectively. In an aspect, each overlap 206-212
may further contain one or more locking mechanisms to secure the
wing span sections in the extended configuration, discussed in
detail herein below, to hold the wing span sections 102-110 in a
fixed position during use at a variety of typical load
conditions.
[0050] The degrees of overlap 206-212 between adjacent wing span
sections 102-110 may be specified to fulfill any one or more of at
least several design goals, including but not limited to: enhancing
the structural integrity in the presence of aerodynamic loads at
selected air vehicle operating conditions, providing the space
necessary to contain the one or more locking mechanisms in a
functionally effective configuration, and minimizing the overall
weight of the wing structure. In an aspect, the degree of overlap
may result from a balance of conflicting design goals, such as the
balancing of reduced weight, which suggests a reduction of the
degree of overlap, against the enhancement of structural integrity,
which suggests an increase in the degree of overlap between
adjacent wing span sections 102-110.
[0051] In an aspect, the degree of overlap may be equal between all
adjacent wing span sections 102-110, as illustrated in FIG. 2. In
another aspect, the degree of overlap may vary between different
pairs of adjoining wing span sections. For example, the degree of
overlap 206 between a pair of inboard wing span sections 102 and
104 may be specified to be higher than the degree of overlap 212
between a pair of more outboard wing span sections 108 and 110. In
this example, the higher degree of overlap 206 preserves the wing's
structural integrity near the wing root 202 where the bending
moments due to aerodynamic wing loads are likely to be higher, and
the lower degree of overlap 212 preserves the wing's structural
integrity near the tip 204 of the wing 100, where the bending
moments are likely to be reduced. In addition, by situating the
higher degree of overlap in those areas likely to experience the
highest loads, the overall weight of the wing 100 may be
reduced.
[0052] In an aspect, the overlap distance between a protruding wing
span section and the adjacent inboard wing span section may range
from about 5% to about 35% of the total spanwise dimension of the
protruding wing span section in the extended configuration. In
another aspect, the overlap distance between a protruding wing span
section and the adjacent inboard wing span section may range from
about 10% to about 20% of the total spanwise dimension of the
protruding wing span section in the extended configuration. In yet
another aspect, the overlap distance between a protruding wing span
section and the adjacent inboard wing span section may be about 15%
of the total spanwise dimension of the protruding wing span section
in the extended configuration. For example, if a wing span section
has a total spanwise dimension of about 9'', this wing span may
have an overlap distance of about 1.5'' (about 16% of the total
spanwise dimension) when the wing is in an extended configuration.
The overlap distances between adjacent wing span sections can and
will vary depending on the particular design requirements of the
air vehicle.
D. Locking Mechanism
[0053] In an aspect, adjacent wing span sections in the extended
configuration may be reversibly secured to each other through an
internal locking mechanism, ensuring stability of the wing
structure during flight and allowing the collapsible wing to
achieve and maintain its full span in the extended configuration.
In an aspect, a locking mechanism may be incorporated at each
overlap region between adjacent wing span sections. Referring back
to FIG. 2, locking mechanisms may be incorporated to secure each of
the overlaps 206-212 in a fixed position when the wing 100 is in an
extended configuration.
[0054] In an aspect, the locking mechanism used to secure a
particular overlap region may include a first locking element
integrated within the structure of the more inboard wing span
section, and a second locking element integrated within the
structure of the more outboard wing span section. For example,
referring to FIG. 2, to secure the overlap 206 in a fixed position
when the wing 100 is in an extended configuration, a first locking
element may be integrated within the structure of the root wing
section 112 and a second locking element may be integrated within
the structure of the wing span section 114. In the extended
configuration, the first locking element may be reversibly engaged
with the second locking element, resulting in a fixed orientation
of root wing section 112 and wing span section 114.
[0055] Any known locking mechanism including any known locking
elements or combination of known locking elements that generate a
reversible holding force may be used as locking elements in the
collapsible wing 100. Non-limiting examples of suitable locking
mechanisms include a friction mechanism, a locking tab mechanism, a
slotted locking mechanism, and a magnetic locking mechanism. The
locking mechanism may be selected based in any one or more of at
least several factors, including but not limited to the added
weight of the locking mechanism, the strength of the locking system
when the elements are reversibly engaged, the size of the locking
mechanism as it relates to the ability of the locking mechanism to
fit within the confines of the collapsible wing, the absence of
external protuberances that may add to the parasite drag of the
collapsible wing in use, and the ability of the locking mechanism
to function without the use of tools and/or with the need to
manipulate internal mechanisms to engage and disengage the locking
elements. The wing span sections of the collapsible wing are held
securely in place during flight by the locking mechanism. To
expedite the deployment of the UAV in the field in time-sensitive
scenarios, the locking mechanism may be selected to be employed
relatively quickly and without need for precise manipulation or
tools. For example, it may be impractical for an operator to use a
screwdriver or insert a locking pin through a small hole while
wearing gloves or other protective gear under adverse field
conditions. Further, the locking mechanism may be selected to be
easily disengaged when collapsing the wing into the collapsed
configuration for wing storage or transport.
[0056] In an aspect, the first and second locking elements may be
attached at any location on the more outboard and more inboard
adjacent wing span sections associated with an overlap region, so
long as the elements of the locking mechanism reversibly engage
when the wing is extended to the extended configuration. At each
overlap region, the locking mechanism may comprise two or more
first locking elements that reversibly engage with two or more
corresponding second locking elements.
[0057] In another aspect, the locking elements associated with one
overlap region may be spatially staggered with respect to other
locking elements associated with the other overlap regions of the
collapsible wing. In this aspect, the staggering of the locking
elements associated with different overlap regions reduces the
inadvertent interaction and/or engagement of locking elements of
different overlap regions, resulting in the locking of the wing
span sections in an incompletely or inappropriately extended
configuration.
[0058] In yet another aspect, the locking mechanism may include
mechanical locking elements. For example, the inner surface of one
wing span section may contain a dimple or socket which reversibly
engages a ball bearing or spring loaded pin mounted on the outer
surface of the adjacent wing in order to secure the extended wing
span sections in place.
[0059] As described previously in FIG. 4, the locking mechanism may
include interlocking flanges 406-412 that mechanically interlock
when the wing 100 is deployed to the extended configuration. In
still another aspect, the locking mechanism may be a frictional
locking mechanism comprising a frictional force between the mating
surfaces of two adjacent wing span sections. In use, the frictional
locking mechanism may prevent the wings of a UAV from collapsing
during flight due to anticipated aerodynamic loads. Upon landing,
the operator of the UAV may manually apply a force sufficient to
overcome the resistance of the frictional locking mechanism and
re-collapse the wing for storage and/or transport.
[0060] As shown in FIG. 5, a frictional force between two wing span
sections such as a wing tip section 502 and a wing root section 504
may result from a frictional lining 506, 508 applied to the inside
of the wing span sections at specific locations such that the
frictional linings 506, 508 engage when the collapsible wing is in
the extended position. The frictional linings may be applied to the
surfaces of both mating wing span sections, as illustrated in FIG.
5, or to only one of the mating wing span sections. The frictional
surfaces may secure the wing span sections upon complete overlap of
the frictional surfaces, as illustrated in FIG. 5, or after a
partial overlap of the frictional surfaces. One or both wing span
sections of an overlap region may further include additional
structural features including, but not limited to, raised ridges,
raised lips, or raised bumps to enhance the function of the
frictional linings in securing the wing in the extended
configuration.
[0061] The frictional lining may be composed of any material
capable of generating sufficient static friction force. For
example, materials having a low Poisson's ratio including, but not
limited to, cork or rubber may serve as a frictional lining
material. The frictional lining material may be a liquid material
including, but not limited to, a rubbery polymer, which may be
coated on to the surfaces of the wing span sections 502 and 504 and
allowed to dry. Because the frictional lining material may be
deformable, the tolerances of the carbon fiber construction of the
collapsible wing may be somewhat relaxed. The frictional lining
material may function both as a locking mechanism and as a
vibration-damping cushion between adjacent wing span sections.
[0062] In an additional aspect, the locking mechanism may be a
magnetic locking mechanism comprising a magnetic force between the
mating surfaces of two adjacent wing span sections. As illustrated
in FIG. 6, the locking elements of the magnetic locking mechanism
may be pairs of magnets 606/608 and 610/612 attached to or
integrated into the skins of the wing root section 604 and the wing
tip section 602. For example, extremely thin, 0.03'' thick magnets
may be integrated into the skin of the wing (which may be about
0.06'' thick in this example). The magnets may be made of a highly
magnetic material including, but not limited to, Grade N-42
neodymium and may provide an attractive force of about 2 lbs. per
pair of magnets in this configuration. In this aspect, from about
two to about four pairs of magnets may provide the magnetic locking
mechanism between adjacent wing sections associated with an overlap
region.
[0063] The poles of the magnets in this aspect may be oriented in
an opposed arrangement in adjacent wing spar sections so that the
alignment of the positive and negative poles may facilitate the
securing of the wing span sections in the extended configuration.
To reduce unwanted magnetic interactions when extending the wing
span sections, the magnets may be arranged in a staggered pattern
so that each magnet attracts only its corresponding counterpart on
the adjacent wing span section. This magnetic locking mechanism
takes advantage of the close spacing tolerances between adjacent
wing span sections, which allow the magnets to be situated
sufficiently close for generating significant magnetic forces. To
collapse the wing, the user may generate a force in the spanwise
direction sufficient to overcome the magnetic forces.
[0064] In another additional aspect, the locking mechanism may be
an external locking mechanism. Any external locking mechanism that
fixes the wing span sections in a fixed position during use may be
used, including but not limited to adhesive tape wrapped around the
overlap region between two adjacent wing span sections. In yet
another additional aspect, "button style" tabs situated in about
2-4 locations on the top and bottom surfaces of a wing span section
may engage corresponding female receptacles formed in the inner
surface of the corresponding inboard wing span section to secure
adjacent wing span sections in place in the extended configuration.
In this aspect, the operator may lift up on the tabs to release
each tab from its corresponding female receptacle, thereby
facilitating the conversion of the wing into the collapsed
configuration.
E. Wind Airfoil Shape and Aerodynamic Design
[0065] The aerodynamic design of the collapsible wing 100 may be
any existing or custom design, and may be selected based on any one
of at least several factors including, but not limited to: the
intended purpose of the aircraft including the collapsible wing
100, the desired weight of the wing 100 and air vehicle, and the
desired aerodynamic performance of the wing 100. Non-limiting
examples of aspects of the aerodynamic performance of the wing 100
include the maximum sectional lift coefficient; aerodynamic
stability; susceptibility to stalling in response to wind gusts,
reduced airspeeds, or severe maneuvers; induced drag; airfoil
sectional lift to drag ratio c.sub.i,max/c.sub.d; overall air
vehicle lift coefficient (C.sub.L); and overall air vehicle drag
coefficient (C.sub.D).
[0066] The maximum sectional lift coefficient (c.sub.i,max) and the
airfoil sectional lift to drag ratio are governed in part by the
airfoil's cross-sectional profile. Without being limited to any
particular theory, the maximum sectional lift coefficient may be
enhanced by the inclusion of camber in the airfoil profile.
However, the inclusion of camber may adversely impact other
characteristics of the collapsible wing structure. For example, the
curvature of cambered wing span sections may possess a higher
overall thickness than a corresponding uncambered wing span
section, which may impact the portability of the collapsible wing
100 in the collapsed configuration due to both the increased size
of the collapsed wing as well as the increased difficulty of
arranging a curved surface within the confines of a typical
backpack used by personnel in remote operations.
[0067] In an aspect, the cross-section airfoil profile may be an
uncambered airfoil, including but not limited to the USNPS4 profile
as illustrated in FIG. 7. Non-limited examples of suitable airfoil
profiles and relevant aerodynamic performance characteristics at a
Reynolds number of 100,000 (representative of the typical operating
conditions of a small unmanned aircraft system (SUAS)) are
summarized in Table 1:
TABLE-US-00001 TABLE 1 Airfoil Sections Suitable for Collapsible
Wing Structures. Airfoil (C.sub.I,max/C.sub.d) C.sub.I,max S7075 53
1.26 S4083 37 1.29 S7055 23 1.33 S8037 40 1.26 SG6043 59 1.43
USNPS-4 52 1.45
[0068] Other aerodynamic characteristics of the wing 100 may be
influenced by other airfoil characteristics, including but not
limited to the wing area, wing loading, wing span, chord length,
camber, thickness, and aspect ratio. For example, aspect ratio,
without being limited to any particular theory, may influence the
induced drag of the air vehicle incorporating the wing 100. In
order to reduce the induced drag, a high aspect ratio wing having a
relatively long wingspan and a relatively narrow chord length may
be indicated. In addition, the chord length at the wing tip may be
shorter than the chord length at the wing root in order to reduce
induced drag. However, in the context of an unmanned aircraft
system, a long wing span may negatively impact the portability of
the collapsible wing, and may further increase the difficulty of
achieving a hand-launch typically used to initiate the flight of
the air vehicle. In addition, a higher aspect ratio may also reduce
the wing area if wing span is not correspondingly increased to
maintain similar aircraft lift characteristics, thereby increasing
the wing loading of the air vehicle.
[0069] In an aspect, the external geometry of the collapsed wing
may be modified to enhance the aerodynamic performance of the wing
in the extended configuration. The outboard edges of each wing span
section may be machined using any known method including but not
limited to grinding, sanding, and chemical machining, in order to
form a more gradual transition from the surface of one wing span
section to the adjacent wing span section. For example, the
outboard edges may be shaped into a flat ramp, a rounded corner, a
series of smaller steps, or any other shapes to make the transition
between adjacent wing span sections more gradual. In another
aspect, the extended wing section may be covered in a tightly
fitting, glove-like covering to smooth out the overall exterior
surface of the wing in order to enhance aerodynamic performance if
a smooth, seamless wing surface is indicated as beneficial given
the anticipated operational environment of the air vehicle. In this
aspect, the glove-like covering may incorporate surface texturing
in critical regions of the wing including, but not limited to, the
upper surface of the wing, in particular in a region located
roughly 25% of the chord length back from the wing's leading edge.
In one aspect, the surface texturing may induce the transition of
the airflow from a laminar flow to a turbulent flow, thereby
enhancing the aerodynamic performance of the wing.
[0070] In an aspect, the aerodynamic design of the collapsible wing
100 trades off the various constraints of the UAS associated with
portability, ability to assemble and launch the air vehicle in the
field, and the aerodynamic performance of the air vehicle in
operation. In one particular aspect, the aspect ratio of the
collapsible wing 100 may range from about 8 to about 10. The wing
loading of the collapsible wing 100 in this aspect may range from
about 1 to about 1.6 lb./ft.sup.2. The aerodynamic design of the
collapsible wing 100 can and will result in any range of dimensions
and features in any combination without limitation including, but
not limited to: wing span, chord length, sweep, taper, camber,
area, and any combination thereof, in accordance with standard
design practices well-known in the art.
E. Materials Used to Construct Collapsible Wings
[0071] The materials used to construct the wing span sections of
the collapsible wing may be any existing material or custom
composite material, in particular any materials commonly used in
the construction of air vehicles. In an aspect, the materials may
be selected based on one or more of at least several factors
including, but not limited to: the strength of the material; the
density of the material; the hardness, durability, and crack
resistance of the material; the sensitivity of the material to
environmental factors associated with use in the field such as
changing temperature, humidity, and abrasion; the cost of the
material; and the ease of fabricating the collapsible wing using
the material. Non-limiting examples of materials suitable for the
construction of a collapsible wing include metals and metal alloys
including but not limited to aluminum, titanium, and steel;
plastic; wood; and composite materials such as carbon fiber epoxy
composite materials.
[0072] In an aspect, the material used to construct the collapsible
wing span sections may be a carbon fiber epoxy composite material,
resulting in an enhanced strength to weight ratio of the resulting
collapsible wing. Any known technique of producing structures from
carbon fiber epoxy composite materials may be used to construct the
collapsible wing span sections including, but not limited to: wet
lay up, dry layup, resin induction molding, compression molding,
and filament winding. The carbon fiber material may be
preimpregnated with resin prior to use, or the resin may be applied
or incorporated into the carbon fiber material after the material
has been arranged into the desired shape for the collapsible wing
span section. Any other known method may be used to fabricate the
collapsible wing span sections without limitation.
[0073] In an additional aspect, the carbon fiber epoxy composite
may be fabricated in at least one or more layers to provide
suitable structural integrity. In another aspect, each wing span
section may be fabricated from one or more layers of carbon epoxy
composite in which the carbon fibers 802-808 of each layer are
aligned at different angles relative to the spanwise direction of
the wing as illustrated in FIG. 8. In an aspect, the angle of each
layer relative to the spanwise direction of the wing may range from
0.degree. to 90.degree.. Without being limited to any particular,
the arrangement of composite fibers illustrated in FIG. 8 may
enhance the structural integrity of the wing span section under a
variety of loading conditions anticipated during use.
[0074] In another aspect, the number of layers of composite
material may range from 1 to about 5 or more, depending on factors
including but not limited to the size of the air vehicle, the
overall wing span, the size of the wing span section, and the
desired weight of the collapsible wing. In yet another aspect, the
number of layers of composite materials may be the same for all
wing span sections of the collapsible wing, or the number of layers
of composite materials may vary between the different wing span
sections. In still another aspect, the number of layers used in the
construction of inboard wing span sections near the wing root may
be higher than the number of layers used for more outboard wing
span sections near the wing tip. In this aspect, the number of
layers used in the construction of the wing span sections may
continuously decrease as a function of outboard distance away from
the fuselage. Without being limited to any particular theory, the
anticipated loading on the wing structure, in particular the
bending moment, may be highest near the wing root and may be
negligible at the wing tip. As a result, less material may be
needed to maintain the structural integrity of the collapsible wing
near the wing tips. Due to the reduction in material achieved in
this aspect, the overall weight of the collapsible wing may be
reduced relative to a wing having a constant number of composite
layers in all wing span sections.
[0075] Without relying on any particular theory, the layout of the
layers in the wing may be custom designed to reinforce the wing
structure in a particular direction or region where significant
forces or stresses may be anticipated under typical operating
conditions of the air vehicle. The customized layer layout may
result from standard engineering analysis methods including, but
not limited to, finite element analysis. In one aspect, the layers
making up the wing may be arranged to produce a wing structure that
possesses sufficient structural integrity while reducing the
overall amount of material and resulting weight of the wing.
[0076] II. Methods of Producing a Collapsible Wing
[0077] The collapsible wing may be produced using any of the
materials described herein above using any known machining or other
fabricating technology appropriate for the selected material of
construction. In one aspect, the material of construction may be
carbon fiber epoxy composite materials, and any known production
method for this material may be used to produce the collapsible
wing including, but not limited to, the wet layup method. In the
wet layup method, each layer of carbon fiber material is applied to
a mold shaped in the desired geometry of the wing span section to
be produced and the epoxy is brushed or otherwise applied to the
carbon fiber material on the mold. After all layers have been
situated in place, the carbon fiber material and epoxy is vacuum
bagged to cure the material for a period ranging from about 24
hours to about 48 hours and to ensure that the material maintains
the intended form and achieves full hardness. In an aspect, the
carbon fiber material and epoxy may be cured without a vacuum bag
under ambient conditions. The mold used to fabricate the wing tip
section may be produced using any known method including but not
limited to machining and rapid prototyping methods, and may be
constructed using any appropriate known material.
[0078] In another aspect, the completed wing tip section may be
used as the mold to fabricate the next wing span section adjacent
to the wing tip section. The initial mold used to create the wing
tip section may remain at the core in the next stages of production
to ensure that subsequent sections maintain the proper shape while
minimizing the chances of deformation resulting from the pressure
of the vacuum during lay-up and curing. In this aspect, the direct
use of the wing tip section assures tight dimensional tolerances of
the fit of the wing tip section into the lumen of the adjacent wing
span section. Once each wing span section is fully cured, it may be
used as the mold for the next adjacent wing span section. Plastic
sheeting and/or mold release compounds or similar material may be
situated between adjacent wing span sections to facilitate the
release of each wing span section from its underlying mold/wing
span section after the wing span section is fully cured. This
process may be repeated for the fabrication of all wing span
sections in the collapsible wing.
[0079] The fabrication technique described in this aspect results
in tightly nested wing span sections in the collapsed
configuration. This fabrication technique may further enhance the
structural integrity of the wing in the extended configuration,
which benefits from tightly-fitting wing span sections due to the
self-supporting monocoque structure of the collapsible wing.
However, the fabrication technique described in this aspect may be
time-intensive because each fabrication step by necessity must be
conducted sequentially. For example, a collapsible wing having five
wing span sections may take in excess of ten days to complete if a
48-hour curing time is assumed for each wing span section. The
method in this aspect is described in further detail herein below
in Example 1.
[0080] In yet another aspect, the wing span sections may be
produced using a separate dedicated mold for each wing span
section. In this aspect, the materials for each wing span section
may be laid up and cured independently of the other wing span
sections, and in one aspect all wing span sections may be laid up
and cured simultaneously. The production method in this aspect may
result in a reduced total fabrication time that is independent of
the number of wing span sections included in the finished
collapsible wing.
[0081] III. Uses of Collapsible Wing
[0082] The collapsible wing, in various aspects, is a
self-supporting and light-weight structure capable of storage and
transportation within a relatively small space in the collapsed
configuration, as well as functioning as a robust wing structure in
the extended configuration. Further, the ability of the collapsible
wing to be deployed without need for tools or intricate
manipulations facilitates a simple and rapid deployment of the
extended wing structure that is well-suited for a variety of
challenging operational environments.
[0083] Several design features of the collapsible wing render the
wing amenable to use in a broad range of applications. A wide
variety of wing sizes and shapes may be achieved by varying the
dimensions of the wing span sections as well as the number of wing
span sections. The structural integrity of the wing may be
fine-tuned by varying the construction of individual wing span
sections, resulting in a wing with robust structural features in
those regions in which the largest structural loads are
anticipated. Thus, the weight of the wing may be reduced by
eliminating excess materials where they are not needed.
[0084] The collapsible wing may be incorporated into any known air
vehicle; the collapsible wing may be scaled up or down in size
according to the requirements of the particular air vehicle in
which the wing is incorporated. The portability and simple
deployment of the collapsible wing makes the wing particularly
amenable to use in the design of field-deployed air vehicles
included in unmanned aircraft systems. In an aspect, the
collapsible wing may be used as the main wing in an air vehicle. In
another aspect, the collapsible wing structure may be used as a
variety of aerodynamic surfaces, including but not limited to
canards, horizontal tails, vertical tails, and wings.
A. Moveable Control Surfaces
[0085] In another aspect, with suitable modification, the
collapsible wing structure may be used as, or in conjunction with,
a moveable control surface including but not limited to a flap, a
slat, an aileron, a rudder, a moveable canard, and an elevator. In
this aspect, illustrated in FIG. 9A, a collapsible wing structure
1008 may be attached to a moveable plate 902 included in the outer
surface of a fuselage of an air vehicle. In the interior of the
fuselage, the movable plate 902 may be operatively connected to an
actuator (not shown) including but not limited to a hydraulic
actuator, a servo-electrical actuator, and a stepper motor. The
actuator, under active control by the operator of the air vehicle,
may impart a rotational motion to the movable plate, which effects
a change in incidence angle of the wing structure 1008, as shown in
FIG. 8B. In other aspects, similar collapsible airfoil structures
attached to movable plates may be incorporated into an UAV for use
as control surfaces including, but not limited to an elevator, a
rudder, or a moveable canard.
[0086] In one aspect, the collapsible wing structure may have a
fixed airfoil geometry and may not incorporate moveable control
surfaces. In another aspect, the collapsible wing structure may
additionally integrate additional moveable controls surfaces,
including, but not limited to, ailerons, slats, and flaps. In this
aspect, the wing structure may incorporate modifications to the
external surfaces and interior lumens of the wing span sections to
provide the necessary actuators, wiring, and other elements used to
effectuate the movement of the additional moveable surfaces.
B. Unmanned Aircraft System
[0087] In an aspect, the collapsible wing may be incorporated into
any known air vehicle as part of an unmanned aircraft system (UAS).
The air vehicle of the UAS may include a first and second
collapsible wing and a fuselage. The first and second collapsible
wings may be identical in design and used interchangeably as right
and left wings in another aspect. Alternatively, the first and
second collapsible wings may have different designs resulting in
the specialized function of the first wing as a left or right wing,
and the specialized function of the second wing as a right or left
wing. In another aspect the UAS may include a full-span collapsible
wing such as the collapsible wing illustrated in FIG. 3 and a
fuselage. The collapsible wings may include an integrated
attachment fitting at the inboard edge of the wing root section
that reversibly engages with a corresponding receptacle integrated
into the fuselage structure in one aspect. In another aspect, the
attachment fitting may be integrated into the structure of the
fuselage, and the corresponding receptacle may reside on the
inboard edge of the wing root section. Any attachment fitting and
receptacle may be incorporated into the design of the UAV. In an
aspect, an attachment fitting and receptacle that do not require
tools or fine manipulation to effect the engagement of the
attachment fitting and receptacle may be used. Non-limiting
examples of suitable attachment devices include a tabbed fitting, a
cleat system, a quick release lever system, and a threaded fitting
and receptacle.
[0088] In use, the UAV may be carried in a disassembled state
within one or more packs carried by one or more persons. In the
disassembled state, both wings are in the collapsed configuration
and may be situated within protective packaging including but not
limited to carrying cases or crates. The fuselage may also be
situated within similar protective packaging.
[0089] To deploy the UAV, the wings may be removed from the packs
and any packaging and deployed into the extended configuration as
described herein above. The wings may be attached by engaging each
attachment fitting of each wing with its corresponding receptacle
situated on the left or right sides of the fuselage. In an aspect,
if the wing is a full-span collapsible wing, the wing may be
deployed in a similar matter and attached to the fuselage at the
upper or lower surface by engaging the attachment fitting, which is
situated at the center section of the wing, to a corresponding
receptacle situated on the fuselage, depending on the design of the
UAV.
[0090] After activating the engine, control system, and any sensors
on board the UAV, the UAV may be hand-launched by throwing the UAV
in the air at an upward angle relative to horizontal ranging from
about 15 degrees to about 30 degrees or more. In other aspects, the
UAV may be launched using other methods or separate devices
including, but not limited to: a dedicated launcher such as a rail
launcher or a catapult launcher; a slingshot; or any other suitable
launch method or device known in the art.
[0091] In an aspect, the collapsible wings of the UAV lack moveable
control surfaces including, but not limited to, ailerons. As a
result, the UAV may accomplish all maneuvering and stabilization
using moveable surfaces associated with the tail of the UAV.
Non-limiting examples of suitable moveable control surfaces for the
UAV include a rudder; an elevator including, but not limited to, an
all-moveable horizontal tail; and a differentially movable
horizontal tail. In another aspect, the UAV may use an all-moveable
horizontal tail to effectuate control in the pitch axis, and a
rudder to effectuate control about the yaw axis, as well as
effectuate rolling maneuvers using rudder-induced sideslip combined
with dihedral effect.
[0092] The UAV may be recovered by any known method including but
not limited to a soft landing, a capture net and the recapture of
the low-flying UAV by the user. Once recovered, the attachment
fittings of the wings may be disengaged from each corresponding
wing fittings on the fuselage. The detached wings may be collapsed
by pushing in an inboard direction on the wing tip section or
otherwise disengaging the locking mechanism. Depending on the
particular locking mechanism used, a sharp tap on the wing tip
section may be needed to initially disengage the locking elements
of the locking mechanism. Once the wings are returned to a
collapsed configuration, the wings and fuselage may be returned to
the packaging and/or packs for transport and/or storage.
DEFINITIONS
[0093] The term "unmanned aircraft system" (UAS), as used herein,
refers to an unmanned aircraft vehicle (UAV) and all equipment and
materials associated with the operation, transport, storage, and
operation of the UAV. Non-limiting examples of equipment and
materials include transport crates or packs; fuels or batteries;
instructions; autopilot receivers; spare parts; training
simulators; and any combination thereof. In the context of this
specification, the terms UAS and UAV may be used interchangeably
without changing the scope or meaning of the information disclosed
herein.
[0094] The term "chordwise", as used herein, refers to a direction
associated with a wing span section extending from the leading edge
to the trailing edge of the wing span section.
[0095] The term "spanwise", as used herein, refers to a direction
associated with a wing span section extending outward from the
fuselage within a horizontal plane. Spanwise may refer to a
direction extending perpendicularly outward from the fuselage, or
spanwise may refer to a direction extending outward from the
fuselage that is parallel to the direction of a central axis of the
wing.
[0096] The term "inboard" and "outboard", as used herein, refer to
relative positions within a horizontal plane extending outward from
the fuselage of an aircraft. Inboard refers to a position that is
relatively closer to the central axis of the fuselage, and outboard
refers to a position that is relatively farther away from the
central axis of the fuselage.
[0097] The term "strutless", as used herein, refers to a structural
design of a wing span section that does not include any significant
internal structural elements, such as spars or ribs, which
typically extend within the interior lumen of a wing between the
upper and lower wing surface and/or between the leading edge and
trailing edge of the wing.
EXAMPLES
[0098] The following example illustrates various aspects of the
invention.
Example 1
Fabrication of Prototype Collapsible Wing
[0099] To demonstrate the feasibility of fabricating a collapsible
wing with extendable wing sections, the following experiments were
conducted. The collapsible wing fabricated in this experiment was
composed of four hollow wing sections that nested inside each other
in the collapsed configuration, where each wing section had a span
length of about 9''. In the extended position, each wing section
inboard of the root section had an exposed span of about 7.5'' and
an overlap of approximately 1.5'' between the adjacent wing
sections.
[0100] The wing sections were fabricated from a carbon fiber epoxy
composite material using a carbon fiber wet layup method. In this
method, the sheets of carbon fiber were soaked with epoxy, and the
epoxy-soaked sheets were then squeegeed to remove excess epoxy to
form epoxy-impregnated carbon fiber sheets. The impregnated sheets
were then wrapped around a mold in the shape of the wing span
section. In order maintain tight tolerances between the wing span
sections, each wing span section was fabricated successively,
starting with the smallest wing span section corresponding to the
wing tip and ending with the largest wing span section
corresponding to the wing root. Plastic sheeting and/or mold
release compound was situated between successive wing span sections
to facilitate the release of the wing span sections after
curing.
[0101] For the wing tip section, three layers of epoxy-impregnated
sheets were laid up around a precise, rapid-prototype mold of a
USNPS-4 airfoil. The three layers were arranged with the fibers of
each sheet aligned in an orientation of about 0.degree.,
45.degree., and 90.degree. relative to the spanwise direction of
the section, respectively, as described previously herein. Multiple
layers of peel ply, a porous fabric, were situated over the layers
of the wing tip section to cover the carbon fiber and soak up any
excess epoxy during the vacuum curing process, thereby reducing any
excess epoxy from the layers of material.
[0102] To cure the wing tip section, a vacuum bag was sealed around
the wrapped mold as shown in FIG. 10, and the wing tip section was
cured under vacuum for about 24 to about 48 hours. After completion
of curing of the wing tip section, the cured wing tip section was
kept on the underlying mold, and was further trimmed and sanded to
provide a suitable surface for the lay-up of the subsequent wing
span section.
[0103] The subsequent wing span section, to be located adjacent to
the wing tip section in the finished collapsible wing, was
fabricated using a series of steps similar to those used for the
fabrication of the wing tip section. Three layers of
epoxy-impregnated carbon fiber sheets were laid up around the cured
wing tip section, as described previously, and cured for about 24
to about 48 hours in the vacuum-sealed plastic bag as described
previously. This process was repeated for each successively wing
span section, using the cured, trimmed and sanded adjacent wing
section as the mold for the laid-up carbon fiber sheets.
[0104] In this manner, each wing span section was laid up around
the immediately adjacent wing span section ensuring that each wing
span section fit precisely inside its larger adjacent wing span
section. The entire collapsible wing was fabricated in a total time
of about eight days; about 48 hours were expended for the
fabrication of each of the four wing sections.
[0105] The resulting cured wing span sections are shown in FIG. 11
prior to separating each cured wing span section from its
underlying adjacent wing span section acting as a mold. The process
of separating the wing span sections from each other is shown in
FIG. 12. After the wing span sections were separated and the
initial wing tip mold removed, the resulting four wing span
sections nested inside each other in a collapsed configuration, as
shown in FIG. 13. A photograph of the prototype collapsible wing
produced in this experiment is shown in FIG. 14 in the extended
position. The completed collapsible wing shown in FIG. 14 weighed
about 1.35 lbs.
[0106] The results of this experiment demonstrated the feasibility
of the fabrication of a collapsible wing using a carbon fiber wet
layup method.
[0107] It should be understood from the foregoing that, while
particular embodiments have been illustrated and described, various
modifications can be made thereto without departing from the spirit
and scope of the invention as will be apparent to those skilled in
the art. Such changes and modifications are within the scope and
teachings of this invention as defined in the claims appended
hereto.
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