Note: Descriptions are shown in the official language in which they were submitted.
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DEPLOYMENT APPARATUS FOR AN UNDERWATER TOWED-ARRAY
ANTENNA
The invention relates to a deployment apparatus, which
can be installed on a water craft, in particular a
submarine, for paying out an underwater towed-array
antenna, which is in the form of a flexible tube, of
the type defined in the precharacterizing clause of
claim 1.
In a known deployment apparatus for an underwater
towed-array antenna which is in the form of a flexible
tube (DE 196 52 737 Cl), the feed unit which acts on
the towed-array antenna and produces a tension force
acting in the deployment direction on the towed-array
antenna has a paying-out tube through which the towed-
array antenna is passed. A large number of inlet
nozzles which pass through the tube wall are arranged
on the paying-out tube and are connected to a high-
pressure water pump. A water flow towards the
deployment end of the paying-out tube is produced
between the tube inner wall of the paying-out tube and
the flexible tube casing of the towed-array antenna by
means of the inlet nozzles. The powerful water flow
causes that section of the towed-array antenna (which
is in the form of a flexible tube) which is located in
the paying-out tube at that time to be driven towards
the deployment end by means of the surface friction
which is produced on the flexible tube casing. In
addition, the water flow produces a lubrication effect,
since the flexible tube casing of the towed-array
antenna is surrounded by a water film and does not
touch the tube inner wall of the paying-out tube, so
that no significant friction forces occur, which would
brake the feeding of the towed-array antenna.
A deployment apparatus having a feed unit, which has
two soft-coated winch heads which run in opposite
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directions and between which the towed-array antenna
which is in the form of a flexible tube is passed, is
also already known (EP 0 124 133 B1). The winch heads,
which are driven by a motor or motors, act on both
sides of the towed-array ant.enna by friction, and move
the towed-array antenna in the direction of the
deployment end of the paying-out tube at the stern of
the submarine. Since the towed-array antenna, which is
in the form of a flexible tube, represents a structure
which bends relatively easily and the part of the
antenna which is located between the drive apparatus
and the deployment end of the paying-out tube is pushed
through the winch heads, it is not possible to reliably
ensure that the towed-array antenna is always deployed
without any disturbances. In addition, the winch heads
subject the towed-array antenna to a high mechanical
load, which. leads to premature wear of the flexible
tube casing of the towed-array antenna, thus resulting
in the towed-array antenna becoming unusable
prematurely.
The invention is based on the object of providing a
deployment apparatus of the type mentioned initially
which allows the towed-array antenna to be paid out
reliably without any disturbances or jamming, and with
a minimal mechanical load on the towed-array antenna.
In accordance with this invention, there is provided a
deployment apparatus which can be installed on a water craft,
in particular a submarine, for paying out an underwater
towed-array antenna which is in the form of a flexible tube,
having a storage drum which holds the towed-array antenna and
can be driven by a motor or motors in order to wind up and
unwind the towed-array antenna, and having a feed unit which
acts on the towed-array antenna and produces a tension force
(which acts in the deployment direction) on the towed-array
antenna, characterized in that the towed-array antenna is
passed over a guide wheel which can be driven by a motor or
motors, and in that a control device is provided which,
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during paying out, synchronizes the drive motors for the
storage drum and for the guide wheel, matched to the tension
force acting on the towed-array antenna, such that the
section of the towed-array antenna which is in each case
located between the storage drum and the guide wheel is
significantly stretched.
The deployment apparatus according to the invention has
the advantage that, during the paying-out process, the
control device matches the rotation angle rates of the
storage drum and of the guide wheel to the tension
force which acts on the towed-array antenna in the
pulling-out direction downstream from the guide wheel
such that the tension force is sufficient to pull that
section of the towed-array antenna which has been
unwound from the storage drum and is in each -case
located between the guide wheel and the storage drum
off the guide wheel, so that the towed-array antenna
does not become jammed between the guide wheel and the
storage drum, thus avoiding the risk to the paying-out
process associated with this. Only a small amount of
mechanical friction occurs on the towed-a.rray antenna,
which is caused by the guide wheel and, even in the
long term, does not lead to damage to the flexible tube
casing of the towed-array antenna.
According to one preferred embodiment of the invention,
at least one force measurement device which senses the
tension force acting on the towed-array antenna is
arranged on the guide wheel. The force which is
measured by the force measurement device is supplied to
the control device as a reference variable. The force
measurement- device makes it possible to detect very
accurately the force acting on the towed-array antenna,
whose magnitude is subject to a certain fluctuation
range and, for example, may rise sharply after
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immersion of the deployment end of the towed-array
antenna in the wake behind the water craft.
Since the storage drum has a significant axial length,
and the towed-array antenna is wound up in a number of
layers on the storage drum in order to allow the towed-
array antenna to be wound up completely, the storage
drum has an associated winding carriage, which can be
moved by a motor or motors parallel to the drum axis
and is fitted with a winding wheel, which is mounted
such that it can rotate, for guidance of the towed-
array antenna. According to one advantageous embodiment
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of the invention, the control device also controls the
feed rate of the winding carriage as a function of the
rotation angle rate of the storage drum.
According to one advantageous embodiment of the
invention, during paying out, the towed-array antenna
is pulled through a guide tube with an inlet and outlet
opening, and the guide wheel is arranged directly
adjacent to the inlet opening of the guide tube such
that the section of the towed-array antenna which runs
out tangentially from the guide wheel is aligned
coaxially with the normal to the inlet opening, that is
to say coaxially with the guide tube axis, so that the
towed-array antenna which runs out from the guide wheel
runs directly and unobstructed into the guide tube.
According to one advantageous embodiment of the
invention, the feed unit acts on the end of the towed-
array antenna and has an antenna end piece which is
firmly connected to the towed-array antenna and has a
large number of moldings which are separated from one
another, are arranged axially on a cable such that they
cannot move significantly, and are designed to produce
a drag in the wake of the water craft. This has the
advantage that, when the end piece is immersed in the
wake, the towed-array antenna is permanently subject to
a tension force which depends on the speed of the
vessel during deployment of the towed-array antenna and
which is sufficiently large to pull the towed-array
antenna out of the guide tube.
According to one advantageous embodiment of the
invention, the moldings can rotate on the cable, so
that they do not apply any rotation moment to the
towed-array antenna via the cable while being towed in
the wake.
According to one advantageous embodiment of the
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invention, each molding has a funnel with a funnel
opening pointing in the towing direction, and has an
end disk which projects beyond the funnel casing and is
arranged at the end facing away from the funnel
opening, with the external diameter of the end disk
preferably being designed to be the same as the
external diameter of the funnel at the funnel opening.
The funnel shape of the moldings, which is open in the
towing direction, with an end disk behind them ensures
a sufficiently high drag in the free flow when the
speed of motion of the water craft is low, and thus
ensures a sufficiently high tension force at the end of
the towed-array antenna.
According to one advantageous embodiment of the
invention, the feed unit has a flushing tube with an
inlet and an outlet opening for the towed-array
antenna, in which a water pressure can be produced
close to the inlet opening. At the start of the paying-
out process, the antenna end piece is inserted in the
flushing tube, with its moldings being guided in the
flushing tube such that they can move axially and have
the water pressure applied to them. This design
addition to the feed unit ensures that a tension force
acting in the deployment direction is applied to the
end of the towed-array antenna right from the start of
the paying-out process, and even before the antenna end
piece has become partially or entirely immersed in the
wake of the water craft, since the external diameter of
the moldings is only slightly smaller than the internal
diameter of the flushing tube, so that the moldings act
like pistons to which water pressure is applied. In
order to allow the water pressure to build up in the
flushing tube, a flushing pump is, according to one
advantageous embodiment of the invention, connected to
a water inlet of the flushing tube, and the inlet
opening of the flushing tube is closed by a seal,
preferably in the form of a labyrinth seal, which
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provides a seal against the towed-array antenna which
is like a flexible tube.
According to one advantageous embodiment of the
invention, axial webs which are offset with respect to
one another, preferably through 90 , are fitted to the
funnel casing for each molding in the circumferential
direction and extend from the funnel opening to the end
disk, and their outer web lines, which run parallel to
the funnel axis, are at a radial distance from the
funnel axis which corresponds to the external diameter
of the end disk. A closure cone which has axial
aperture openings is fitted to the funnel opening. The
conical shape of the closure cone, the axial webs and
the end disk whose circumference is rounded ensure that
the moldings center themselves in the flushing tube and
do not become jammed on tolerance-dependent steps in
the flushing tube. The chosen length of the moldings
prevents jamming in the flushing tube. The closure cone
advantageously assists the process of threading the
antenna end piece into the flushing tube during
recovery of the towed-array antenna.
Since, according to one advantageous embodiment of the
invention, the moldings are produced from a material
which slides well, for example Teflon, the friction
losses on the moldings in the flushing tube are
reduced, thus increasing the proportion of the tension
force which can be used for pulling out the towed-array
antenna.
According to one advantageous embodiment of the
invention, the last molding in the towing direction has
a stop, preferably in the form of a truncated conical
closure element which is integral with the end disk and
is designed to close the outlet opening of the flushing
tube. This stop prevents the antenna end piece from
being pulled through the flushing tube during recovery
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of the towed-array antenna. The moment at which the
closure element stops against the flushing tube can be
sensed, and can be used to switch off the drive motors
after recovery of the towed-array antenna.
According to one advantageous embodiment of the
invention, the flushing tube is integrated in the guide
tube and can move in an axially limited manner in it
against a spring force, so that the striking of the
stop or of the closure element on the flushing tube is
sprung, before the drive motors are switched off.
The invention will be described in more detail in the
following text with reference to an exemplary
embodiment which is illustrated in the drawing, in
which:
Figure 1 shows an outline sketch of a
deployment apparatus for a towed-array
antenna,
Figures 2 each show a graph in order to explain
to 5 the operation of a control device in
the deployment apparatus shown in
Figure 1,
Figure 6 shows a perspective illustration of
the deployment apparatus shown in
Figure 1,
Figure 7 shows an enlarged illustration of the
detail VII in Figure 6, without a
guide tube,
Figure 8 shows a longitudinal section through a
feed unit in the deployment apparatus
shown in Figure 6,
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Figure 9 shows a perspective illustration of a
funnel part of a molding of the feed
unit shown in Figure 8,
Figure 10 shows a view of the funnel part in the
direction X in Figure 9,
Figure 11 shows a section along the line XI - XI
in Figure 10,
Figure 12 shows a view from underneath of a
closure cone, which can be fitted to
the funnel part, of the molding of the
feed unit shown in Figure 8, and
Figure 13 shows a section along the line XIII -
XIII in Figure 12.
The deployment apparatus, which is illustrated in the
form of an outline circuit diagram in Figure 1 and in
the form of a perspective illustration in Figure 6, for
an underwater towed-array antenna which is like a
flexible tube is installed on a water craft which is
not illustrated here, in particular on a submarine. In
the case of a submarine, it is installed between the
flooded outer casing and the pressure body. The towed-
array antenna 10 comprises, in a known manner, a towed
section and a traction cable, which connects the towed
section to the water craft. The towed section comprises
a flexible tube casing which is filled with liquid or
gel and in which a large number of electroacoustic
transducers are arranged in a row, separated from one
another. A damping module, a so-called VIM, is arranged
between the towed section and the traction cable.
When not in use, the towed-array antenna 10 is wound up
in a number of layers on a storage drum 11 which can be
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driven by means of a drive motor 11, with the storage
drum 11 having a significant axial length in order to
accommodate the quite long towed-array antenna 10. The
storage drum 11 has an associated winding carriage 12
which can be moved by a motor or motors parallel to the
drum axis and has a winding wheel 13 mounted on it such
that it can rotate. The winding wheel 13 guides the
towed-array antenna 11 while it is being wound onto or
unwound from the storage drum 11, with the winding
carriage 12 carrying out a controlled backward and
forward movement along the storage drum 11. A guide
wheel 14 is arranged at a distance from the storage
drum 11 in the direction of the stern of the water
craft and is mounted in a stand 15 such that it can
rotate, which stand 15 is in turn fixed in a frame or
platform 16, which is indicated schematically in
Figure 1. At least one force measurement device 17, and
in the illustrated exemplary embodiment two force
measurement devices 17, is or are arranged between the
stand 15 and the platform 16, and measures or measure
any change in the contact force applied by the stand 15
to the platform 16. The guide wheel 14 can be driven by
a motor or motors, for which purpose at least one
electric motor 141 is provided. The towed-array antenna
10 runs from the storage drum 11 over the winding wheel
13 and the guide wheel 14, and is passed through a
guide tube 18 with an inlet opening 181 and an outlet
opening 182, which is located in the open water behind
the stern of the water craft. The guide wheel 14 is
arranged directly adjacent to the inlet opening 181 of
the guide tube 18, so that the antenna section which
runs off tangentially from the guide wheel 14 is
aligned coaxially to the normal to the inlet opening
181, so that the towed-array antenna 10 runs coaxially
into the guide tube 18. During the paying-out process,
a tension force FA which pulls the towed-array antenna
10 through the guide tube 18 is applied to the end of
the towed-array antenna 10, to be more precise to the
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end of a damping module (VIM) which is also arranged
here and is connected to the towed section. The tension
force FA is produced by means of a feed unit 19 which
will be described later.
A control device 20 is provided in order to ensure that
the paying-out process or deployment process for the
towed-array antenna 10 takes place without any
disturbances or jamming, and synchronizes the drive
motors 111 and 141 for the storage drum 11 and for the
guide wheel 14 matched to the tension force FA which is
sensed by the force measurement device 17, such that
the towed-array antenna section which is in each case
located between the storage drum 11 and the guide wheel
14 is significantly stretched, that is to say it runs
without hanging down. For this purpose, the rotation
angle rates VT and vF of the storage drum 11 and of the
guide wheel 14 are matched to the tension force FA such
that the latter can pull the length of the towed-array
antenna 10 which has in each case been unwound from the
storage drum 11 by its motor 111 through the guide tube
18, and the towed-array antenna 10 cannot become
"jammed" in front of the guide wheel 14 or on the guide
tube 18. The pulling-out force FA which is sensed by
the force measurement device 17 is used as a reference
variable in the control device 20 for adjustment of the
rotation angle rates VT and VF of the storage drum 11
and of the guide wheel 14. For this purpose, the
reference variable FA is supplied to a first regulator
21 for the control device 20. This regulator 21 is also
supplied with the actual rotation angle rates VFact and
VTact of the guide wheel 14 and of the storage drum 11
which are sensed by respective rotation sensors 22 and
23, which are arranged on the guide wheel 14 and on the
storage drum 11, respectively. The reference variable
FA is used to determine the nominal rotation angle rate
VFnom of the guide wheel 14 and the nominal rotation
angle rate VTnom of the storage drum 11 and to regulate
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it via the nominal value outputs of the control device
20 for the drive motors 111 and 141 for the storage
drum 11 and for the guide wheel 14. The characteristics
for the control process are shown in Figures 2 and 3.
When the tension force FA rises, then both the nominal
value for the rotation angle rate vT of the storage
drum 11 and the nominal value for the rotation angle
rate vF of the guide wheel 14 are increased linearly.
At the same time, as can be seen from the
characteristic in Figure 4, a positive slip s is
superimposed on the guide wheel 14, which is reduced as
the reference variable increases and ensures that that
section of the towed-array antenna 10 which is in each
case located between the guide wheel 14 and the storage
drum 11 is stretched without hanging down.
A second regulator 24 in the control device 20 is used
to control the feed rate vs of the winding carriage 12
as a function of the rotation angle rate vT of the
storage drum 11. For this purpose, the second regulator
24 is supplied with the nominal rotation angle rate
vTnom of the storage drum 11 and with the actual feed
rate vsact of the winding carriage 12. The latter is
detected by means of a rotation sensor 25, which senses
the rotation angle rate of a transmission output drive
shaft or of the output drive shaft of the motor 121.
The nominal feed rate vsnom is controlled in the drive
motor 121 via the corresponding nominal value output.
Figure 5 shows the characteristics of the second
regulator 24, with the characteristic a being
applicable while the towed-array antenna 10 is being
pulled off the upper of the total of three winding
layers, and with the characteristic b being applicable
to the two winding layers below this, that is to say to
the second and first winding layer. The latter is
formed exclusively by the traction cable for the towed-
array antenna.
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The feed unit 19 for producing the tension force FA at
the deployment end of the towed-array antenna 10 is
illustrated in the form of details in Figures 6 and 7,
and in the form of a longitudinal section in Figure 8.
It comprises an antenna end piece 26, which is firmly
connected to the towed-array antenna end, as well as a
flushing tube 40 which is integrated in the guide tube
18 and in which the antenna end piece 26 is inserted
when the towed-array antenna 10 has been pulled in and
is wound up on the storage drum 11. As can be seen from
Figure 8, the antenna end piece 26 has a large number
of moldings 27, which are arranged at a distance from
one another, such that they cannot move significantly
axially, on a cable 28 which is firmly connected to the
towed-array antenna 10. The arrangement is in this case
designed such that the moldings 27 can rotate around
the cable 28. For simplicity, Figure 8 shows the end
piece 26 connected directly to the towed-array antenna
10, to be more precise to its VIM. In order to allow
the end piece 26 and the type of towed-array antenna 10
to be changed easily, the cable 28 is attached to a
flexible tube element which is associated with the end
piece 26 and is itself connected to the VIM of the
towed-array antenna. The flexible tube element
comprises an elastic flexible tube casing which is
filled with liquid or gel and is stiffened by means of
a molding. A loose pulled-in cable prevents
unacceptably large expansion of the flexible tube
casing.
The moldings 27, which are produced from a material
which can slide well, such as Teflon, are physically
identical. Each molding 27 is in two parts and is
composed of an elongated funnel part 29, which is
illustrated in detail in Figures 9 to 11, and a closure
cone 30, which is illustrated in the form of a view
from underneath and a longitudinal section in Figures
12 and 13. A funnel 31 with a funnel opening 32 which
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points in the towing direction, as well as an end disk
33 which is arranged at that end of the funnel part
which faces away from the funnel opening 32, are formed
in the funnel part 29, with the end disk 33 projecting
radially beyond the funnel casing 311. The outline
edges of the end disk 33 are rounded toward both disk
surfaces. The rounded areas are annotated 331 in
Figure 11. A cylindrical annular rim 34 is positioned
in front of the funnel opening 32, and the unobstructed
diameter of this annular rim 34 is designed to be equal
to the diameter of the funnel opening 32, while its
external diameter is designed to be equal to the
external diameter of the end disk 33, which, in the
exemplary embodiment, is approximately half as large as
the axial length of the funnel part 13. Four axial webs
35, which are arranged offset through 90 with respect
to one another in the circumferential direction, are
fitted to the funnel casing 311 and each extend from
the annular rim 34 to the end disk 33. The outer web
line 351 of the axial webs 35, which runs parallel to
the funnel axis, is at a radial distance from the
funnel axis which is equal to the external radius of
the end disk 33 and the external radius of the annular
rim 34. A central aperture hole 36, which opens in the
base of the funnel, is incorporated in the end disk 33.
The closure cone 30, which is fitted to the funnel part
29, has three axial aperture openings 37, which are
offset through a rotation angle of 120 with respect to
one another, as well as a central aperture hole 38. The
aperture openings 37 are made sufficiently large that,
in practice, only webs remain between them, and these
webs are arranged in a star shape. The aperture hole 38
runs at the star point. An annular web 39 projects
axially from that end of the closure cone 30 which
faces the funnel opening 32, and its external diameter
is designed to be slightly smaller than the internal
diameter of the annular rim 34 on the funnel part 29,
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so that the closure cone 30 can be inserted, with its
annular web 29, in an interlocking manner into the
annular rim 34 on the funnel part 29. Once the cable 28
has been threaded through the aperture openings 37 and
38, the funnel part 29 and the closure cone 30 are
firmly connected to one another, for example by means
of a number of screw connections, which are radially
offset on the circumference, between the annular rim 34
and the annular web 39. The moldings 27 are prevented
from being able to move axially on the cable 28 by
means, for example, of knots in the cable 28, with the
funnel base and the base area of the closure cone 30
each being supported on one cable knot.
The flushing tube 40 of the feed unit 19 together with
an inlet opening 401 and an outlet opening 402 for the
towed-array antenna 10 (Figures 7 and 8) is pulled into
the guide tube 18 and can move axially to a limited
extent in the guide tube 18 against the force of a
compression spring 41. The outlet opening 402 of the
flushing tube 40 is located at or close to the outlet
opening 182 of the guide tube 18. A Y-tube branch 42 is
fitted to the inlet opening 401 of the flushing tube
40, and is firmly connected to the flushing tube 40 and
to the guide tube 18 by means of a screw sleeve 43. The
towed-array antenna 10 is inserted into the tube
connecting stub 421 (which is coaxial with the flushing
tube 40) of the Y-tube branch 42, with a labyrinth seal
44 providing a seal between the tube inner wall and the
flexible tube casing of the towed-array antenna 10
which is largely pressure-tight. The other tube
connecting stub 422, which runs at an acute angle to
the tube connecting stub 421, of the Y-tube branch 42
forms a water inlet 45, and is connected to a flushing
pump 47, which is indicated only schematically here and
allows water pressure to build up in the flushing tube
40.
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Once the towed-array antenna 10 has been wound up
completely on the storage drum 11, the antenna end
piece 26 which is attached to the end of the towed-
array antenna 10 by means of the cable 28 is pulled,
together with its moldings 27, completely into the
flushing tube 40. The end of the towed-array antenna 10
and the flexible tube element of the antenna end piece
26 which is connected to the towed-array antenna 10
project into the inlet opening 401 of the flushing tube
40. At the inlet of the towed-array antenna 10 or of
the flexible tube element into the tube connecting stub
421 of the Y-tube branch 42, a labyrinth seal 44 seals
the tube inner wall against the towed-array antenna 10,
which is in the form of a flexible tube, and the
flexible tube element. The moldings 27, whose external
diameter is only slightly less than the unobstructed
diameter of the flushing tube 40, are guided in the
flushing tube 40 by means of the end disk 33, the
annular rim 34 and the axial webs 35, and can slide
well by virtue of the material which is used to produce
them. If, for example, a water pressure of 2 - 3 bar is
now produced in the flushing tube 40 at the start of
the deployment process or paying out of the towed-array
antenna 10, then the moldings 27 act like pistons,
which are shifted by the water pressure in the
direction of the outlet opening 402 of the flushing
tube 40, and thus produce the tension force FA on the
towed-array antenna 10 via the cable 28. After reaching
the outlet opening 402 of the flushing tube 40, the
moldings 27 emerge successively from the flushing tube
and enter the wake behind the water craft. The
antenna end piece 26 which has been pulled completely
out of the flushing tube 40 then produces the tension
force FA owing to its drag as it is pulled through the
35 water, with this tension force FA being governed by its
drag and by the towing speed of the water craft. This
tension force also ensures that the towed-array antenna
10 is pulled out through the flushing tube 40 without
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any disturbances until its entire length has been
deployed in the water and it remains connected at its
front end via the traction cable, which has likewise
been pulled out, to the storage drum 11 which is fixed
on the water craft.
During recovery of the towed-array antenna 10 and while
being wound up on the storage drum 11, the moldings 27
on the antenna end piece 26 can be inserted into the
flushing- tube 40 without any problems owing to the
closure cone 30 which precedes the funnel part 29. A
truncated conical closure element 46 is arranged on the
last molding 27 on the antenna end piece 26 and is
designed to close the outlet opening 402 of the
flushing tube 40, and to form a stop in order to limit
the pulling-in movement of the towed-array antenna 10.
The closure element 46 is attached to the end disk 33.
Alternatively, it may be attached to the cable 28 or
may be formed integrally with the end disk 33. Once the
antenna end piece 26 has been pulled in completely,
then the closure element 46 stops against the flushing
tube 40, and the flushing tube 40 is moved in the guide
tube 18 against the force of the compression spring 41.
The axial movement of the flushing tube 40 or the
increase in the spring force of the compression spring
41 is sensed and this is used to generate a switching-
off signal for the motors 111, 121 and 141 for the
storage drum 11, the winding carriage 12 and the guide
wheel 14.
