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Description  |
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This invention relates to deployable systems and, more particularly, to
deployable solar array panels and antennas for a spacecraft using an
extensible boom.
Deployable solar array panel structures, as used with spacecraft, generally
include a number of relatively large panels hinged at parallel axes. The
panel array is attached at one end to a spacecraft. The panels, during
launch of the spacecraft, are folded accordion like, one over the other,
with the panels facing one another. When the spacecraft reaches its
orbiting position, the panel array is released permitting the panels to
unfold and deploy.
One deployment system utilizes spring loaded hinges which unfold the
released panels and are described, for example, in U.S. Pat. No.
4,133,502. However, such hinges in a relatively long deployment system,
for example, 60 feet or more utilizing an array of eight foot long panels,
may allow bending of the array in response to acceleration of the
satellite during stationkeeping maneuvers. Such bending motions tend to
interfere with satellite control. Thus, a relatively long array requires a
relatively stiff support boom not provided by such hinges. The spring
loaded hinges also have the disadvantage of not being retractable.
A second kind of deployment system utilizes linear extenders which are
retractable. Examples of such systems are illustrated in U.S. Pat. Nos.
3,783,029 and 3,677,508. A linear extender includes a boom which comprises
a strip of spring metal which is wound in flat condition on a motor driven
reel within an actuator and is prestressed to automatically curl laterally
into a tubular configuration as it leaves the reel. The boom exits from
the actuator through a guide which is sized to slidably receive the boom
in its tubular configuration. The actuator motor is reversible to drive
the actuator reel in either direction to extend the boom from or retract
the boom into the actuator. Panels employed with such a system, however,
as disclosed in the aforementioned U.S. Pat. No. 3,783,029, comprise a
substrate which is preferably a thin film of Mylar, Kapton, or other
plastic relatively lightweight material for receiving the solar cells.
Mylar, Kapton, and other plastic supporting structure for a solar cell
panel have certain drawbacks. For one, those substrates usually are
required to be tensioned to increase their rigidity. Further, such
substrate materials have relatively high coefficients of thermal expansion
and, therefore, tend to exhibit large dimensional changes during exposure
to widely varying temperature excursions.
Relatively rigid panels, which are more thermally stable than the thin film
substrates, are more widely used with the spring loaded, non-retractable
hinge type deployment system. These panels comprise composite materials
such as aluminum or fabric honeycomb core material sandwiched between
faces of composite fabrics as disclosed, for example, in U.S. Pat. No.
4,394,529. The more rigid panels tend to be heavier than the Mylar,
Kapton, and other plastic substrates and, therefore, require a relatively
strong support structure which can withstand bending due to inertial
forces created in response to spacecraft accelerations induced, for
example, by stationkeeping maneuvers.
There is presently an additional commercially available self-erecting boom
known as the "Astro mast." The Astro mast is depicted generally in FIG. 13
herein. The Astro mast is a relatively stiff structure when extended and
exhibits minimum bending for relatively long extended lengths, e.g., 60
feet or more. This structure also has the advantage of being coilable into
a relatively small volume of several cubic feet. That mast is generally
used for deploying relatively lightweight radio antennas and the like at
its extended end and is of relatively complex construction.
The present inventors recognize that the Astro mast is a relatively stiff
structure and, therefore, is an attractive alternative as a support for
solar array panels comprising composite materials employing honeycomb
cores and the like discussed above. A problem with deploying rigid solar
array panels with a boom, such as the Astro mast, lies in attaching the
solar array panels to the mast as it extends and retracts. The panels are
not easily attachable to such a boom because of its relatively more
complex structure and due to the need to minimize play between the array
and mast to minimize undesirable motions during stationkeeping maneuvers.
There is a current need for a coilable helix antenna for use in the UHF
bandwidth. Such an antenna can have a length of thirty feet or more. The
helix angle of the coils is critical and must be maintained. The linear
extender mentioned above is not applicable for this kind of antenna
because the extender's metal structure tends to interfere with the
antenna's radiation characteristics. The use of hinged posts for such an
application becomes unwieldy for reasons similar to that mentioned above
in connection with long panel arrays. As recognized by the present
inventors, the solar array panel structures and the helix antenna,
however, have a common structure; i.e., they are collapsible.
According to the present invention, a deployment system for a collapsible
structure comprises a support and an extensible boom secured to the
support. The structure is elongated and extended in the deployed
orientation and collapsed and folded in the retracted orientation. First
means pivotally secure an end of the collapsible structure to the boom
adjacent to an end of the boom. Second means releasably secure selected
spaced portions of the collapsible structure along its length to various
points along the length of the boom with negligible play as the boom
extends. The securing means also uncouples the selected portions from the
boom as the boom retracts. The second means includes means for aligning
the structure to the boom when the portions are uncoupled from the length
of the boom. Means are coupled to the support and boom for selectively
extending and retracting the boom.
In the drawing:
FIG. 1 is a fragmented side elevation view, partially in section, of a
solar cell panel deployment system in accordance with one embodiment of
the present invention;
FIG. 2 is a plan view of the embodiment of FIG. 1;
FIG. 3 is an isometric view of the embodiment of FIG. 1, somewhat
schematic, illustrating the panels partially deployed;
FIG. 4 is a fragmented elevation view of a portion of the embodiment of
FIG. 1 with the panels omitted and the boom extended;
FIG. 5 is a perspective view illustrating the emergence of one panel
coupling element of the embodiment of FIG. 1 which connects to a second
panel coupling element for releasably securing the panels to an
extensible, coilable boom;
FIG. 6 is a perspective view of the panel and boom coupling elements of
FIG. 5 after their engagement;
FIG. 7 is a plan view of one of the coupling elements secured to the boom
taken along lines 7--7, FIG. 4;
FIG. 8 is a plan view illustrating several of the panel to boom coupling
elements of FIG. 7 superimposed to illustrate their indexing arrangement;
FIG. 9 is a plan view of a second coupling element hinged to selected ones
of the panels and adapted to releasably engage the coupling element of
FIG. 7;
FIG. 10 is an elevation view of a portion of the structure of FIG. 9 taken
along lines 10--10;
FIG. 11 is a more detailed isometric view of an indexing projection used
with the structure of FIG. 10;
FIG. 12 is a more detailed isometric view of a cord guide assembly of the
structure of FIG. 9;
FIG. 13 is a side elevation view, somewhat schematic, of a second
embodiment of the present invention with the solar cell panels partially
deployed; and
FIGS. 14-17 illustrate a third embodiment of the present invention.
In FIG. 1, spacecraft 10 is illustrated in a launch configuration carrying
a folded stacked solar cell panel array system 12. The spacecraft 10 may
carry one or more such systems. System 12 is symmetrical relative to axis
14 passing through the spacecraft 10 center of gravity. System 12
comprises a plurality of panels 16 hinged together at their edges along
parallel hinge axes. End panel 18 is connected by hinges 146 to top plate
142 of boom 24, FIG. 2, along hinge axis 140. Plate 142 is trapezoidal and
is secured to the end of boom 24, FIG. 3. In the stacked condition plate
142 rests above panel 18, FIG. 1, over a somewhat larger trapezoidal
opening 147, FIG. 2, in panel 18. Plate 142 also has clearance openings
142' and 143' for devices attached to adjacent members when stacked.
End panel 18 also has a clearance opening 18.sub.1 for adjacent devices
when stacked. Panel 18 is hinged at one end thereof to full size panel 19
at hinge axis 18', FIG. 3, which, in turn, is hinged to a pair of smaller
panels 20 and 20', at hinge axis 19' and so forth. The pair of smaller
panels 20 and 20' are spaced apart by distance large enough to permit them
to unfold without interfering with boom 24. In the folded configuration,
the full size panels are stowed on one side of boom 24 and the pairs of
smaller panels are stowed on the other side of boom 24. The end panel 18
is larger than the remaining panels and covers the folded stack of panels.
Panel 19 is less than half the area of panel 18 and, in particular, has a
length dimension l which is less than half the length dimension l' of
panel 18. Panels 20 and 20' have the same length which is greater than
length l of panel 19. The difference in length l of panel 19 and the
length of panels 20, 20' is the transverse dimension of the boom 24 so
the panels have a symmetrical mass relative to axis 14 when folded.
A second pair of panels 21 and 21', each having the same length and width
dimensions as panels 20 and 20', are hinged thereto on hinge axis 27. The
set of panels 20, 20', 21, and 21' define a rectangular opening 23
slightly wider than the width of boom 24. Full size panels 26 and 28 are
dimensioned the same as panel 19 and are hinged at respective parallel
hinge axes 29, 31, and 35 as shown.
A set 30 of four smaller panels 30', 30", 30.sub.1, and 30.sub.2 are
dimensioned the same as the set of panels 20, 20', 21, and 21' and define
an opening 32 similar to opening 23. Openings 23 and 32 permit the
respective adjacent panels to fold past the boom 24 so that the boom is in
the middle of the folded stack. Folded panels 33 and 34 have the same
dimensions as and are hinged to panels 30.sub.1 and 30.sub.2 and, as
shown, have not yet been unfolded. The remaining folded panels repeat the
panel set 30 and panels 33 and 34 in the order illustrated.
The array of panels 16, when deployed, are on one side of the boom 24 with
the solar cells (not shown) facing the viewer. In this way none of the
cells are in the shadow of the boom and insure maximum power generation.
In a communications satellite it is desirable that the solar array panels
be deployed along an axis passing through the center of gravity of the
spacecraft such as axis 14.
The boom 24, FIG. 3, as mentioned in the introductory portion, in one
implementation may be the Astro mast, which is commercially available. In
FIG. 5, boom 24 comprises a set of identical flexible thermoplastic high
strength rods, square in cross-sectional area, e.g., a fraction of an
inch, which form longerons 36, 38, and 40 and a plurality of battens,
e.g., 46, 47, and 48, which control the geometry of the deployed boom 24.
While deployed, the batten elements are not permitted to fully straighten
by virtue of the lengths of small diameter flexible wire struts, e.g.,
struts 56 that become taught. Boom 24 is relatively rigid when extended,
but yet, is capable of being coiled, collapsed and flattened so as to fit
within a small volume canister. For example, the boom 24 when extended may
be 60 feet or more in length but yet can collapse into a volume of just
several cubic feet.
The longerons 36, 38, and 40 are relatively stiff yet are sufficiently
flexible so as to be coiled into a canister 42. The lower end of the
longerons 36, 38, and 40 are secured to a wheel (not shown) rotatably
secured to the bottom interior wall of canister 42. Canister 42 has three
aligned rotatable interior helical longeron guide tracks 44 concentric
about axis 14, each track simultaneously receiving and guiding a different
one of longerons 36, 38, and 40.
In FIG. 1, canister 42 comprises a fixed cylindrical shell 68 and an
internally mounted rotatable nut 70 in the upper part of the shell
carrying the rotating longeron tracks 44. Nut 70 is rotated by a pair of
drive motors 72 secured to shell 68. While the nut 70 is rotated its
helical tracks 44 containing the longerons 36, 38, and 40 of the boom 24,
FIG. 5, force the longerons into the lower part of the shell 68 cavity or
out of the shell depending upon the nut direction of rotation. When the
longerons 36, 38, and 40, FIG. 5, are driven out of the shell 68 they are
driven parallel to axis 14 by three corresponding guides 54 (only one
being shown), FIG. 5. The battens, e.g., battens 46, 47, and 48, are
attached to the longerons forming a plurality of spaced triangularly
shaped regions normal to axis 14. Each batten terminates at a connector
attached to the corresponding longeron. For example, battens 46 and 47 are
connected to connector 50, battens 46 and 48 are connected to connector
51, and battens 47 and 48 are connected to connector 52. Rotatably secured
to each connector 50, 51, and 52 is a corresponding thermoplastic roller
such as roller 53 at connector 50. The rollers 53 roll in respective ones
of the three corresponding helical guide tracks 44, each track guiding a
different longeron roller and are guided into the tracks by the three
respective guide devices 54 having roller guide tracks parallel to axis
14. Each rectangular frame formed by a set of parallel battens 47, 47' and
the bounded longerons such as longerons 36 and 40 are diagonally
crisscrossed by a set of two struts, e.g., struts 56'.
In FIG. 7, a typical connector 58 comprises a link 60 to which a pair of
battens, e.g., battens 83 and 85, are secured. A body 62 is pivoted to the
link 60 and roller 64 is rotatably attached to body 62. Body 62 can pivot
about axis 66 relative to link 60. A longeron such as longeron 40 is
bonded to a body 62' which can rotate about axis 67 relative to body 62.
This construction permits the longerons 36, 38, and 40 to coil about axis
14, FIG. 5, while permitting the battens 46, 47, and 48 to remain
connected to the respective connectors 50, 51, and 52. The battens 46-48
are dimensioned to bow somewhat outside the cavity of canister 42 when the
boom is erected. Inside the cavity when collapsed, the struts 56, because
they are flexible strings, collapse, permitting the battens to stack
within the canister 42 cavity. The plane of the battens, such as, for
example, the triangular plane formed by battens 46, 47, and 48 and the
respective connectors 50, 51, and 52 remains relatively intact as the
longerons are coiled into the canister 42. This is important for reasons
explained below. Because of the inherent stiffness in the longerons and
battens, the struts 56 and 56' on each side of the boom are stretched taut
by the bowed battens which tend to straighten when the boom is erected,
thus stiffening the boom. The boom and canister structure, as described so
far, is commercially available.
Because the boom collapses within the canister 42, FIG. 5, the problem of
coupling the panels 16, FIG. 3, to the boom as it erects itself from the
canister with negligible play is not without difficulty. The mechanism for
coupling the panels to the boom will now be described. The mechanism,
generally, includes a plurality of aligned indexing bracket assemblies 74,
74.sub.1-5, FIGS. 4, 7, and 8, secured to the boom even when collapsed and
a like plurality of mating corresponding bulkhead assemblies, such as
assemblies 90, 95-99, FIGS. 1, 3, 4, and 9, each hinged at a given hinge
axis, to a set of corresponding panels, e.g., at axes 19', 29, 35, and so
forth, FIG. 3. The bulkhead assemblies remain hinged to the panels when
the panels are stacked and released from the boom, FIG. 1, and, when the
panels are attached to the boom and deployed, FIGS. 3 and 4.
As will be described in more detail below, the indexing assemblies each
have a corresponding bulkhead assembly. Each indexing assembly releasably
engages the corresponding bulkhead assembly as that indexing assembly
emerges from the canister 42, FIG. 5, aligned with that bulkhead assembly,
and disengage from the corresponding bulkhead assembly as the boom is
collapsed into the canister. In the latter case, the bulkhead assemblies
and panels automatically stack in a predetermined alignment as shown in
FIG. 1. In the stacked condition, only the top panel 18 remains coupled to
the boom via top plate 142; all of the remaining panels are completely
free of any direct coupling to the boom, e.g., by way of hinges. However,
the bulkhead assemblies when stacked, are aligned relative to the boom
axis 14 and the indexing bracket assemblies by posts 128, 128', and 128",
secured to canister 42, FIG. 4, as will also be described in more detail
below.
In FIG. 7, indexing bracket assembly 74 is secured to a set of battens 83,
85, and 87 lying in a plane. Indexing bracket assembly 74 comprises a
triangular member 76 having a central opening 82 and three identical arms
77, 78, and 79 extending away from axis 14 along three equal spaced radial
lines 77', 78', and 79', respectively. Typical arm 77 includes a pair of
spaced projections 80, an indexing aperture 81, and a U-shaped clip 89
screwed to arm 77 for securing the arm to batten 83. Arms 78 and 79 are
similarly secured to respective battens 85 and 87. Projections 80 bow the
battens in a given bias direction. When the boom 24 is erected as
mentioned, the battens tend to bow. The biasing bow places the battens
attached to the different indexing assemblies in the bowed state of the
erect boom to preclude potential failure or binding of the system which
might otherwise occur should the battens be clamped in place without a
bow. That bowing action is necessary to stress the struts when the boom
extends in the erect state. Because each bracket assembly, e.g., assembly
74, remains secured to the battens, e.g., battens 83, 85, and 87, when the
boom 24 is extended and retracted, it is important that the triangular
members, e.g., member 76, be dimensioned to fit within the canister 42 as
the longerons are coiled.
In FIG. 8, the six different indexing bracket assemblies 74, 74.sub.1-5 are
superimposed one over the other aligned on axis 14 to illustrate the
relative positions of the spaced indexing apertures. The indexing
apertures of each bracket assembly, such as apertures 81 of member 76, lie
on different corresponding sets of radial lines extending from axis 14.
One of apertures 81 lies on radial line 81', for example, aperture
81.sub.1, of member 74.sub.2 lies on radial line 81.sub.1 ', and so forth.
All of the apertures 81, 81.sub.1, and so forth of the superimposed arms
of the different bracket assemblies when viewed in a direction parallel to
axis 14 are spaced and lie on a line, such as line 84. The apertures of
the remaining arms, for example, the array 93 of apertures corresponding
to arms 78 and so forth and the array 95 of apertures corresponding to arm
77 and so forth lie on respective lines 93', and 95' in similar spaced
relation. It is to be understood that when the boom is extended the
assemblies 74, 74.sub.1, 74.sub.2, and so on, are in spaced relation, one
over the other, FIG. 4.
In FIG. 4, (the panels are omitted for simplicity of illustration) bracket
assembly 74 is aligned adjacent hinge axis 19' of panels 19, 20, and 20'
(FIG. 3). A second indexing bracket assembly 74.sub.1 is aligned adjacent
hinge axis 29 of panels 21, 21', and 26. A third indexing bracket assembly
74.sub.2 is aligned adjacent hinge axis 35 and so on. Thus, an indexing
bracket assembly is aligned adjacent to alternate hinge axes for the
length of the panel 16 array, FIG. 3. In FIG. 4, the battens are connected
underneath the indexing bracket assemblies with the clips, such as clip
89, FIG. 7, facing canister 42. In FIG. 5, because the indexing bracket
assemblies are fixed to the boom, their indexing apertures 81 and so forth
have a given orientation and alignment as they emerge from the canister 42
due to the alignment of the longerons by the tracks of devices 54.
In FIG. 9, representative bulkhead assembly 90 is hinged at the hinge axis
19' to panels 19, 20, and 20' by hinges 92 and 94 (see also FIG. 3). Hinge
92 secures assembly 90 to panels 19 and 20' and hinge 94 secures assembly
90 to panels 19 and 20. Bulkhead assembly 90 is representative of five
additional bulkhead assemblies 95, 96, 97, 98, and 99, FIG. 4. Bulkhead
assembly 95 is hinged to panels 21, 21', and 26, FIG. 3, bulkhead assembly
96 is hinged to panels 28, 30', and 30", and bulkhead assembly 97 is
hinged to panels 30.sub.1, 30.sub.2, and 33. Bulkhead assemblies 98 and 99
are hinged to additional panels not shown in FIG. 3.
Bulkhead assembly 90, FIG. 9, comprises a member 91 having a triangular
central opening 100 and a plurality of spaced triangular openings 101,
103, 105, 107, 109, and 111. The same reference numerals with primes (')
and double primes (") on a bulkhead assembly represent identical parts.
Opening 100 is dimensioned to pass the boom 24, FIG. 7, therethrough along
the boom axis 14; whereas the other openings conserve weight. Member 91
has three land regions 102, 104, and 106, interconnected by ribs, e.g.,
ribs 115, 117, 119, 121, and so forth, each region being spaced along a
respective side of the triangular opening 100. Regions 102 and 106 are
mirror images. Each land region borders on opening 100 with two similar
parallel spaced ribs. For example, ribs 108 and 110 border region 102,
ribs 108' and 110' border region 104 and so forth.
In FIG. 10, the ribs, e.g., ribs 108 and 110, bordering a land region,
e.g., region 102 (FIG. 9) of each bulkhead assembly, have a linear array
of identically spaced and aligned apertures of the same dimension. In
FIGS. 5 and 9, secured to selected ones of the apertures 111 of ribs 108
and 110 is an indexing projection 112. Projection 112, FIGS. 10 and 11,
has an L-shaped body 113 and a depending prong 114. The prong 114
comprises a tapered split pin dimensioned to closely engage in
interference resilient fit one of the indexing apertures, e.g., aperture
81, of the bracket indexing assemblies 74, 74.sub.1 -74.sub.5, FIG. 8. The
prong is resiliently compressed when engaged and this fit precludes play
and looseness between the prong 114 and the mating aperture. The body 113
is threaded so it can be screwed to selected ones of apertures 111, FIG.
10, of the ribs, e.g., ribs 108 and 110. The body 113, fits between the
ribs. Because the apertures 111 of all of the ribs 108 and 110 of each
bulkhead assembly are identically spaced and dimensioned, a projection 112
is selectively secured to those apertures 111 which align prong 114
attached thereto with a mating aperture, e.g., aperture 81, of an indexing
bracket assembly, as that bracket assembly emerges from the canister. A
projection 112 is secured to each set of ribs, e.g., set 108, 110; 108',
110'; and 108", 110" of each bulkhead assembly. The prongs 114 of a given
set are aligned to mate with the set of apertures of a corresponding
indexing assembly; the alignment on the different bulkhead assembly being
different so as to engage only its mating indexing assembly.
In FIG. 5, for example, the prong 114 extends toward the canister 42 and is
aligned with an aperture 81 of the bracket indexing assembly 74 member 76
and engages that aperture as the boom ascends out of the canister in
direction 116. The bulkhead assembly has three identical projections 112,
112', and 112", each secured to the corresponding ribs of the adjacent
land regions 102, 104, 106 and are aligned to simultaneously engage the
respective indexing apertures corresponding to aperture 81 of a given
mating bracket indexing assembly as that bracket assembly emerges from the
canister.
Secured to each of the land regions 102, 104, and 106 are respective
identical contact force spring motors 118, 118', and 118". A typical
spring motor comprises two reels mounted for rotation about parallel axes.
A flat metal spring band has one end attached to one reel and a second end
attached to the other reel. The band is normally wound on one of the reels
and is connected to wind about the other reel as the other reel rotates.
The rotation of the empty reel winds the band about it and causes the band
to build up latent stresses which, when released, cause the band to rewind
upon the reel about which it has unwound. Spring motors are widely known.
In FIG. 5, a reel 120 of high strength cord 122 is attached to the empty
reel of the spring motor 118. An end of cord 122 is threaded to pass over
roller 127 of guide 124, FIG. 12, and through an aperture 125 in region
102. The cord 122 free end is attached to the next adjacent bulkhead
assembly member, e.g., assembly 95, FIG. 4. The cord 122, when extended,
FIG. 4, is under tension induced by motor 118 which is stressed to rewind
the cord 122 tending to pull assemblies 95 and 90 together. In similar
fashion, the spring motors 118', 118" FIG. 9, have respective cords 122'
and 122" similarly attached to assembly 95. Spring loaded cords 122, 122',
and 122", FIG. 4, are positioned substantially symmetrical relative to
axis 14, FIG. 9, to provide a uniform tensile load between bulkhead
assemblies 90 and 95.
Because the boom 24 is being urged in direction 116 by the drive mechanism
in canister 42, the spring load of cords 122, 122', and 122" in direction
123 pull the bulkhead assembly 90 and its corresponding projections 112,
112', and 112", FIG. 9, in a direction to maintain locking engagement of
the prongs 114, FIG. 10, with the apertures 81 of the bracket indexing
assembly 74, FIG. 5. This spring force loading thus keeps the mating
bulkhead and bracket indexing assemblies engaged while the boom is
extended. Similar spring motors, but of different sizes, are on each
bulkhead assembly and are similarly attached to the next adjacent lower
bulkhead assemblies in direction 123 toward canister 42.
The lowermost bulkhead assembly 99, FIG. 4, is resiliently pulled toward
canister 42 in direction 123 by three spring motors 132, 132', and 132"
which are secured to canister 42 outer shell 68. Motors 132, 132', and
132" pull on tapes 134, 134', and 134" secured to the lowermost bulkhead
assembly 99. The forces exerted by the lowermost spring motors 132, 132',
and 132" are the greatest and the forces exerted by the uppermost motors
118, 118', and 118" are the least. The springs motors of each bulkhead
assembly increase in force magnitude, by way of example, by a factor of
roughly 3 pounds for each bulkhead assembly closer to the canister 42. The
forces exerted by motors 132, 132', and 132" may be, for example, 5 pounds
each, that of the next motors 4 pounds each, the next motors 3 pounds
each, and so on. These force differences are necessary so that the
lowermost assembly of a coupled bulkhead assembly pair is pulled toward
canister 42 against the pull of the spring motors of the uppermost
bulkhead assemblies. That is, the motor of an upper bulkhead assembly
tends to pull a lower bulkhead assembly in a direction 116 thus tending to
disengage it from the engaged indexing bracket assembly. To preclude such
disengagement, the motor of the next lower assembly pulls that assembly
toward its next adjacent lower assembly with a greater force and so on
until the lowermost bulkhead assembly is pulled toward the canister 42
with the greatest force. These motors thus insure all bulkhead assemblies
and indexing assemblies remain engaged during deployment.
At the apexes of the triangular opening 100 of bulkhead assembly 90, FIG.
9, are three respective identical alignment apertures 126, 126', and 126".
The apertures 126, 126', and 126" are dimensioned to be closely received
by corresponding respective identical upstanding stepped posts 128, 128',
and 128" secured to ring 130 on the upper rim of canister 42, FIGS. 1 and
4. Typical post 128' has a plurality of different diameter stepped
shoulders. Aperture 126', FIG. 9, is dimensioned to closely enga | | |
