U.S. patent application number 11/243888 was filed with the patent office on 2007-04-05 for parachute with skirt reefing system.
Invention is credited to Calvin K. Lee.
Application Number | 20070075189 11/243888 |
Document ID | / |
Family ID | 37885976 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070075189 |
Kind Code |
A1 |
Lee; Calvin K. |
April 5, 2007 |
Parachute with skirt reefing system
Abstract
A parachute system has a canopy, suspension lines that extend
from the canopy skirt to a confluence point, and a center line that
is attached to and between the apex of the canopy and the
confluence point. A single reefing line cutter is attached to the
center line and is activated after a predetermined amount of time
has elapsed. A first reefing line extends through a first group of
reefing rings wherein one end of the first reefing line is attached
to the single reefing line cutter and the opposite end is attached
to the canopy skirt at a first predetermined location. A second
reefing line extends through a second group of reefing rings that
is opposite the first group of reefing rings. The second reefing
line has one end attached to the single reefing line cutter and an
opposite end attached to the canopy skirt at a second predetermined
location that is across from the first predetermined location. The
canopy opens to an initial circumference that is determined by the
summation of the lengths of the first and second reefing lines.
When the reefing line cutter is activated, the reefing line cutter
releases the first and second reefing lines so as to allow full
inflation of the canopy.
Inventors: |
Lee; Calvin K.; (Needham,
MA) |
Correspondence
Address: |
US Army Soldier Systems Center
15 Kansas Street
Natick
MA
01760
US
|
Family ID: |
37885976 |
Appl. No.: |
11/243888 |
Filed: |
October 5, 2005 |
Current U.S.
Class: |
244/147 |
Current CPC
Class: |
B64D 17/343
20130101 |
Class at
Publication: |
244/147 |
International
Class: |
B64D 17/00 20060101
B64D017/00 |
Goverment Interests
STATEMENT OF GOVERNMENT INTEREST
[0001] The invention described herein may be manufactured and used
by the U.S. Government for Governmental purposes without the
payment of any royalties thereon.
Claims
1. A parachute system, comprising: a canopy having a skirt and an
apex; a plurality of reefing rings attached to the skirt; a
plurality of suspension lines, each suspension line having a first
end attached to the skirt near a corresponding reefing ring and a
second end opposite the first end, all of the second ends of the
suspension lines being connected together to define a confluence
point; a center line attached to the apex of the canopy and the
confluence point; a single reefing line cutter that is attached to
the center line and which is activated after a predetermined amount
of time has elapsed; a first reefing line extending through a first
group of the plurality of reefing rings, the first reefing line
having a first end attached to the single reefing line cutter and a
second end attached to the skirt at a first predetermined location;
a second reefing line extending through a second group of the
plurality of reefing rings, the second group of reefing rings being
generally opposite the first group of reefing rings, the second
reefing line having a first end attached to the single reefing line
cutter and a second end attached to the skirt at a second
predetermined location that is across from the first predetermined
location; and whereby when the parachute system is deployed, the
canopy opens to an initial circumference that is determined by the
summation of the lengths of the first and second reefing lines and
whereby when the single reefing line cutter is activated, the
reefing line cutter releases the first and second reefing lines so
as to allow full inflation of the canopy.
2. The parachute system according to claim 1 wherein the lengths of
the first and second reefing lines are substantially the same.
3. The parachute system according to claim 1 wherein the first and
second predetermined locations are substantially diametrically
positioned with respect to each other.
4. The parachute system according to claim 1 wherein the single
reefing line cutter is attached to the center line at a
predetermined position such that when the canopy opens to the
initial circumference, the single reefing line cutter is at
generally the same vertical level or position as are the first and
second reefing lines.
5. The parachute system according to claim 1 wherein the single
reefing line cutter comprises a pyrotechnic cutter.
6. The parachute system according to claim 1 further including a
line loop attached to the single reefing line cutter wherein the
first ends of the first and second reefing lines are connected to
the line loop and wherein the single reefing line cutter cuts the
line loop when the single reefing line cutter is activated.
7. The parachute system according to claim 1 wherein the center
line has a thickness of about one (1) inch.
8. A parachute system, comprising: a canopy having a skirt and an
apex; a plurality of reefing rings attached to the skirt; a
plurality of suspension lines, each suspension line having a first
end attached to the skirt near a corresponding reefing ring and a
second end opposite the first end; a plurality of risers, each
riser having a first end attached to the second end of a
corresponding suspension line, each riser including a second end
opposite the first end of the riser, all of the second ends of the
risers being connected together to define a confluence point; a
center line attached to and between the apex of the canopy and the
confluence point; a single reefing line cutter that is attached to
the center line and which is activated after a predetermined amount
of time has elapsed; a first reefing line extending through a first
group of the plurality of reefing rings, the first reefing line
having a first end attached to the single reefing line cutter and a
second end attached to the skirt at a first predetermined location;
a second reefing line extending through a second group of the
plurality of reefing rings, the second group of reefing rings being
opposite the first group of reefing rings, the second reefing line
having a first end attached to the single reefing line cutter and a
second end attached to the skirt at a second predetermined location
that is across from the first predetermined location; and whereby
when the parachute system is deployed, the canopy opens to an
initial circumference that is determined by the summation of the
lengths of the first and second reefing lines and whereby when the
single reefing line cutter is activated, the single reefing line
cutter releases the first and second reefing lines so as to allow
full inflation of the canopy.
9. The parachute system according to claim 8 wherein the first
reefing line has a first length and the second reefing line has a
second length that is substantially the same as the first
length.
10. The parachute system according to claim 8 wherein the single
reefing line cutter is attached to the center line at a
predetermined position such that when the canopy opens to the
initial circumference, the single reefing line cutter is at
generally the same vertical level or position as are the first and
second reefing lines.
11. The parachute system according to claim 8 wherein the single
reefing line cutter comprises a pyrotechnic cutter.
12. The parachute system according to claim 8 further including a
line loop attached to the single reefing line cutter wherein the
first ends of the first and second reefing lines are connected to
the line loop and wherein the single reefing line cutter cuts the
line loop when the single reefing line cutter is activated.
13. The parachute system according to claim 8 wherein the single
reefing line cutter is sewn to the center line.
14. The parachute system according to claim 8 wherein the first and
second predetermined locations are substantially diametrically
positioned with respect to each other.
Description
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a parachute with
a skirt reefing system.
[0004] 2. Description of the Related Art
[0005] Large cargo parachutes typically have diameters of about one
hundred feet and are made of solid cloth. Due to the large amount
of canopy fabric, the opening process of such relatively large
cargo parachutes is typically controlled in order to allow the
canopy to open in stages thereby ensuring proper and safe
inflation. A common technique used to control the opening process
of the canopy is skirt reefing. Skirt reefing involves the use of a
reefing line or cord with a length that is less than the
circumference of the canopy skirt when the canopy is fully opened.
The reefing line is attached to the skirt by sliding it through the
reefing rings permanently attached to the canopy skirt at each
suspension line junction. During initial parachute opening, the
skirt opens to a circumference defined by the length of the reefing
line thereby controlling and retarding the opening process. After
this initial stage of parachute opening, the reefing line is then
cut by pyrotechnic cutters which have preset firing times. Once the
reefing line is cut, the skirt is released and the canopy continues
to open. Depending on the size of the canopy and the desired degree
of control of the canopy opening process, multi-stage opening can
be achieved with several sets of reefing lines and pyrotechnic
cutters.
[0006] FIG. 1 illustrates a prior art parachute system. Four
separate reefing lines 10, 12, 14 and 16 are attached to skirt 18
of canopy 20. This prior art parachute system utilizes pyrotechnic
cutter 22, 24, 26 and 28. Reefing line 10 is connected to cutters
22 and 26. Reefing line 12 is connected to cutter 22 and 24.
Reefing line 14 is connected to cutters 26 and 28. Reefing line 16
is connected to cutters 24 and 28. Suspension lines 29 are
connected to skirt 18. For purposes of clarity, not all suspension
lines 29 are completely shown. Each suspension line 29 is connected
in tandem to corresponding riser 30. In order to increase the drag
force, center line 32 is connected between apex 34 of canopy 20 and
the confluence point 36 wherein all risers 30 meet. Center line 32
is symmetrically located with respect to skirt 18 and is spaced
from skirt 18 by radius R. Lanyard 38 connects payload 40 to risers
30. During the opening of canopy 20, center line 32 is tightly
extended due to the weight of the payload 40 and the high air
pressure inside canopy 20. A disadvantage of such prior art skirt
reefing technique is the relatively high cost resulting from the
use of a plurality of pyrotechnic cutters. The cost of such
pyrotechnic cutters has steadily increased over the years and such
cost contributes to the overall annual cost of conducting many
cargo airdrops. For example, the U.S. Department of Defense
conducts several thousand cargo airdrops using clusters of cargo
parachutes every year for military and humanitarian causes.
Therefore, the accumulated cost for using so many pyrotechnic
cutters on these cargo parachutes is very significant.
[0007] What is needed is a cargo parachute system with skirt
reefing that is relatively more economical to implement.
SUMMARY OF THE INVENTION
[0008] In one aspect, the present invention is directed to a
parachute system comprising a canopy having a skirt and an apex, a
plurality of reefing rings attached to the skirt, and a plurality
of suspension lines. Each suspension line has a first end attached
to the skirt near a corresponding reefing ring and a second end
opposite the first end. All of the second ends of the suspension
lines are connected together to define a confluence point. The
parachute system further comprises a center line that is attached
to and between the apex of the canopy and the confluence point, and
a single reefing line cutter that is attached to the center line.
The single reefing line cutter is activated after a predetermined
amount of time has elapsed. The parachute system further includes a
first reefing line that extends through a first group of the
plurality of reefing rings. The first reefing line has a first end
attached to the single reefing line cutter and a second end
attached to the skirt at a first predetermined location. The
parachute system further includes a second reefing line that
extends through a second group of the plurality of reefing rings.
The second group of reefing rings is approximately opposite the
first group of reefing rings. The second reefing line has a first
end attached to the single reefing line cutter and a second end
attached to the skirt at a second predetermined location that is
across from the first predetermined location. When the parachute
system is deployed, the canopy opens to an initial circumference
determined by the summation of the lengths of the first and second
reefing lines. When the single reefing line cutter is activated,
the first and second reefing lines are released thereby allowing
full inflation of the canopy.
[0009] In a related aspect, the present invention is directed to a
parachute system having a canopy which has skirt and an apex. The
parachute system further comprises a plurality of reefing rings
attached to the skirt, and a plurality of suspension lines. Each
suspension line has a first end attached to the skirt near a
corresponding reefing ring and a second end opposite the first end.
The parachute system further includes a plurality of risers. Each
riser has a first end attached to the second end of a corresponding
suspension line. Each riser includes a second end opposite the
first end of the riser. All of the second ends of the risers are
connected together to define a confluence point. The parachute
system also includes a center line attached to and between the apex
of the canopy and the confluence point, and a single reefing line
cutter that is attached to the center line. The single reefing line
cutter is activated after a predetermined amount of time has
elapsed. The parachute system further includes a first reefing line
that extends through a first group of the plurality of reefing
rings. The first reefing line has a first end attached to the
single reefing line cutter and a second end attached to the skirt
at a first predetermined location. The parachute system further
includes a second reefing line that extends through a second group
of the plurality of reefing rings. The second group of reefing
rings is approximately opposite the first group of reefing rings.
The second reefing line has a first end that is attached to the
single reefing line cutter and a second end that is attached to the
skirt at a second predetermined location that is across from the
first predetermined location. When the parachute system is
deployed, the canopy opens to an initial circumference that is
determined by the summation of the lengths of the first and second
reefing lines. When the single reefing line cutter is activated,
the first and second reefing lines are released thereby allowing
full inflation of the canopy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The foregoing features of the present invention will become
more readily apparent and may be understood by referring to the
following detailed description of an illustrative embodiment of the
present invention, taken in conjunction with the accompanying
drawings, in which:
[0011] FIG. 1 is an elevational view of a prior art parachute
system;
[0012] FIG. 2A is an elevational view of the parachute system of
the present invention; and
[0013] FIG. 2B is an enlarged view of a portion of the view of FIG.
2A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Referring to FIGS. 2A and 2B, there is shown parachute
system 100 of the present invention. Parachute system 100 generally
comprises canopy 102 having apex 103 and skirt 104. Parachute
system 100 further includes a first plurality of reefing rings 106
and a second plurality of reefing rings 107. Reefing rings 106 and
107 are attached to skirt 104. In a preferred embodiment, the
reefing rings 107 are oppositely located with respect to reefing
rings 106. Parachute system 100 includes a plurality of suspension
lines 108. For purposes of clarity, some of the suspension lines
108 are either not shown or are only partially shown. Each
suspension line 108 has a first end attached to skirt 104 near a
corresponding reefing ring 106 or reefing ring 107. Each suspension
line 108 also has a second end opposite its first end. In one
embodiment, the second end of each suspension line 108 is attached
to one end of a corresponding riser 110. The opposite ends of
risers 110 are connected together at link 112 thereby defining
confluence point 114. Lanyard 116 is connected to link 112 and
payload 120. Parachute system 100 further includes center line 130
that is connected to apex 103 and link 112. As will be explained in
the ensuing description, center line 130 remains generally
centrally located with respect to canopy skirt 104 during the
parachute opening process. Center line 130 has a diameter thickness
that is capable of withstanding significant tension. In a preferred
embodiment, center line 130 has a thickness of at least one inch.
In a preferred embodiment, center line 130 is fabricated from heavy
webbings to withstand the high tension forces. As shown in FIG. 2A,
a single reefing line cutter 132 is attached to center line 130.
Single reefing line cutter 132 is configured to be activated after
a predetermined amount of time has elapsed. In one embodiment,
reefing line cutter 132 is sewn to center line 130. In a preferred
embodiment, reefing line cutter 132 is a pyrotechnic cutter having
a built-in time delay.
[0015] As shown in FIG. 2B, line loop 134 is attached to reefing
line cutter 132. Parachute system 100 further includes reefing line
140 that extends through reefing rings 106. Reefing line 140 has a
first end attached to line loop 134 and a second end connected to
skirt 104 at a first predetermined location 142. Parachute system
100 further comprises second reefing line 150 that extends through
reefing rings 107. The second reefing line 150 has a first end
attached to line loop 134 and a second end connected to skirt 104
at a second predetermined location 152 that is across from the
first predetermined location 142. In a preferred embodiment, the
first and second predetermined locations 142 and 152, respectively,
are substantially diametrically positioned with respect to each
other. In a preferred embodiment, single reefing line cutter 132 is
positioned on center line 130 at a predetermined position so that
when canopy 102 opens to an initial circumference prior to
disreefing, single reefing line cutter 132 is at generally the same
vertical level or position as are reefing lines 140 and 150. Stated
another way, single reefing line cutter 132 is preferably
positioned on center line 130 so that prior to disreefing, single
reefing line cutter 132 is positioned neither above nor below
reefing lines 140 and 150. Such a configuration facilitates the
disreefing process.
[0016] Referring to FIGS. 2A and 2B, during the opening process,
there is a significant amount of tension on center line 130 thereby
causing center line 130 to remain generally centrally located with
respect to canopy skirt 104. Reefing lines 140 and 150 are of equal
lengths. In one embodiment, reefing lines 140 and 150 are
configured to have lengths that provide the same amount of skirt
reefing as in the prior art parachute system shown in FIG. 1. In
such a configuration, each reefing line 140 and 150 has a length
that is equal to the summation of the lengths of reefing lines 10
and 12 and the radius R of the reefed skirt (see FIG. 1). Referring
to FIGS. 2A and 2B, reefing line cutter 132 can be configured to
have any desired delay time. In one embodiment, reefing line cutter
132 is configured to have a delay time that is the same as the
delay time of the pyrotechnic cutters 22, 24, 26 and 28 used in the
prior art parachute system shown in FIG. 1. In a preferred
embodiment, line loop 134 is fabricated from the same material from
which reefing lines 140 and 150 are fabricated.
[0017] Referring to FIGS. 2A and 2B, when reefing line cutter 132
is activated, it cuts line loop 134 so as to release reefing lines
140 and 150. When parachute system 100 is deployed (i.e. dropped
from an aircraft), canopy 102 opens to an initial circumference.
This initial circumference is less than the circumference of canopy
skirt 104 when canopy 102 is fully inflated. Specifically, this
initial circumference is determined by the sum of the lengths of
reefing lines 140 and 150. When reefing line cutter 132 is
activated, reefing line cutter 132 cuts line loop 134 thereby
releasing reefing lines 140 and 150 and allowing full inflation of
canopy 102.
[0018] Parachute system 100 provides several advantages over the
prior art parachute systems. One advantage is that once reefing
lines 140 and 150 are released, the opening process of canopy 102
is controlled, symmetrical and safe because center line 130 remains
generally centrally located with respect to the canopy skirt 104.
Another advantage of parachute system 100 is that it utilizes a
single reefing line cutter 132 instead of a plurality of reefing
line cutters thereby reducing costs and expense.
[0019] In an alternate embodiment, risers 110, shown in FIG. 2A,
are not utilized. Instead, the ends of suspension lines 108 are
directly connected to link 112.
[0020] The principles, preferred embodiments and modes of operation
of the present invention have been described in the foregoing
specification. This invention should not be construed as limited to
the particular forms disclosed, as these are to be regarded as
illustrative rather than restrictive. Variations and changes may be
made by those skilled in the art without departing from the spirit
of the invention. Accordingly, the foregoing detailed description
should be considered as exemplary in nature and not limiting the
scope and spirit of the invention as set forth in the attached
claims.
* * * * *