Countermeasure hovering test fixture

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates generally to an apparatus for facilitating measurement of the hovering ability of a countermeasure device, and more particularly to an apparatus for retaining a countermeasure device in a vertical guide path to enable testing of the hovering and depth control capabilities of the countermeasure device.

(2) Description of the Prior Art

The use of acoustic countermeasure devices in undersea warfare is common throughout the world. Some of these devices are required to hover in place, and therefore utilize a propeller and motor system to enable the countermeasure device to hover. During the design of these countermeasure devices, the hovering ability must be tested in order to determine the performance of the system. When testing the hovering capabilities of the countermeasure device, it is important that the countermeasure device only be allowed to travel in a vertical plane in order to eliminate any horizontal movement which may interfere with the testing of the countermeasure device.

Furthermore, conventional testing of the hovering capabilities of countermeasure devices requires that the testing be done in large water tanks which can accommodate the size of the entire countermeasure device.

What is needed therefore, is an apparatus for testing the hovering ability of countermeasure devices, which provides a vertical guide path for the countermeasure device for restricting travel of the countermeasure device in a vertical plane. Such an apparatus would enable convenient and accurate testing of hovering countermeasure devices and would reduce the size of the tank in which the tests are conducted.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an apparatus which is capable of restricting the travel of a hovering countermeasure device in a vertical path to enable the hovering ability of the countermeasure device to be tested.

It is a further object of the invention to reduce the volume of water necessary for performing hovering tests of countermeasure devices.

The present invention is directed to a test fixture for testing hovering performance of a countermeasure device tailcone. The tailcone includes a motor and a propeller which is driven by the motor. The test fixture has an upper support device, a lower support device, at least one cable connected between the upper and lower support devices and a connection device which slidably attaches the tailcone to at least one cable. The fixture thereby restricts movement of the tailcone along the at least one cable. The upper support device is supported above a water-filled tank, the lower support is disposed in the water-filled tank and the hovering capability of the tailcone is tested by operating the tailcone in the tank. The connection device includes a number of extensions affixed to the tailcone. The number of extensions each include a clasp spaced from the tailcone, wherein the cables are threaded through the clasps, thereby attaching the tailcone to the cables. The fixture further includes a winch attached to the upper support device, wherein one of the cables is wound onto the winch, the winch being operative for taking up the cable attached thereto, thereby pulling the lower support device from the tank.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein:

FIG. 1

is a plan view of a conventional countermeasure device;

FIG. 2

is a perspective view of the test hardware used in conjunction with the present invention;

FIG. 3

is a plan view of the countermeasure hovering test apparatus of the present invention; and

FIG. 4

is a plan view of an alternate embodiment of the test hardware used in conjunction with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing figures, there is shown in

FIG. 1

, a conventional countermeasure device, generally indicated at

10

. The countermeasure device

10

includes a body portion

12

for housing acoustic equipment, a tailcone shell

14

which houses the motor and controls (not shown) for the hovering system and an outboard propeller

16

which is driven by the motor and provides thrust to the countermeasure device

10

.

FIG. 2

is a perspective view of the test tailcone and the test hardware, generally indicated at

20

. The test tailcone

20

includes the tailcone shell

14

and a test bulkhead

22

. Test bulkhead

22

is attached to the tailcone shell

14

in order to seal the tailcone shell

14

to prevent water from entering the tailcone shell

14

during the testing procedure. Test bulkhead

22

also houses a connection apparatus which enables power and depth command signals to be transmitted to the tailcone shell

14

via a sealed hose connection

24

(See FIG.

3

). The test tailcone

20

also includes four guide rods

26

, each of which includes an extension

28

and an eyelet clasp

30

, the purpose of which is described with reference to

FIG. 3

, below. The guide rods

26

are attached to the test tailcone

14

in a conventional manner, such as by bolting or welding.

Referring now to

FIG. 3

, the test guide structure, generally indicated at

40

, will now be described. The test guide structure

40

includes a top plate

42

which is supported by a crane hook

44

, which enables the test guide structure

40

to be lowered into position above a water-filled testing tank which includes a floor, partially shown at

46

a,

and a top rim, partially shown at

46

b.

A first cable

48

a

is attached at one end to the top plate

42

in a conventional manner and is attached at the other end to a weight plate

49

. A second cable

48

b

is wound onto a winch

50

at the one end thereof, and attached to the weight plate

49

at the other end thereof. The winch

50

is attached to the top plate

42

in a conventional manner. The cables

48

a

and

48

b

are connected between top plate

42

and weight plate

49

such that when the test guide structure

40

is deployed, as shown in

FIG. 3

, the cables

48

a

and

48

b

are parallel to each other. A set of weights

52

can be mounted on the weight plate

49

. Cables

48

a

and

48

b

can be joined to weight plate

49

. These weights

52

operate to allow tension to be applied to cables

48

a

and

48

b

between the top plate

42

and the weight plate

49

to tighten the cables

48

a

and

48

b,

thereby providing more stable operation.

The operation of the countermeasure device hovering test fixture of the present invention will now be described with reference to FIG.

3

. In order to set up the test guide structure

40

, the structure is lowered into position above the top rim

46

b

of the tank by the crane hook

44

and a crane (not shown). At this point, the cable

48

b

is wound onto the winch

50

, causing the weight plate

49

to hang vertically from the cable

48

b.

Once the top plate

42

is in position above the tank, the cable

48

b

is unwound from the winch

50

, thereby lowering the weight plate

49

into the tank until it rests on the floor

46

a

of the tank. Once the weight plate

49

is positioned on the floor

46

a

of the tank such that cables

48

a

and

48

b

are parallel with each other, the test tailcone

20

is attached to the cables by attaching the eyelet clasps

30

on each side of the test tailcone

20

to the corresponding cable

48

a

and

48

b,

as shown in FIG.

3

.

In this configuration, the test tailcone

20

is restricted to moving only vertically along the guide path defined by the cables

48

a

and

48

b.

With power and depth command signals being provided to the test tailcone

20

via the sealed hose connection

24

, the hovering capabilities of the test tailcone

20

can be ascertained. Since no horizontal movement of the test tailcone

20

is possible, more accurate determinations of the hovering ability of the test tailcone

20

can be made.

In addition to providing a guide path for testing the test tailcone

20

, the weight plate

49

provides a mechanical stop for the test tailcone should it fail to operate and also facilitates the retrieval of the test tailcone

20

simply by reeling in the cable

48

b

with the winch

50

to pull the weight plate

49

and the test tailcone

20

from the tank. While the weight plate

49

is shown and described as being fixed to the cables

48

a

and

48

b,

it will be understood that the weight plate

49

can be configured with a pulley system which enables the weight plate

49

to be lowered into the tank in a horizontal orientation.

In

FIG. 4

, there is shown an alternative embodiment of the test hardware used in conjunction with the present invention. The alternative test hardware is generally indicated as

60

which can be used as a replacement for hardware

20

shown in

FIGS. 2 and 3

. In this alternative, a countermeasure

62

has a tailcone

64

with fins

66

disposed thereon. A propeller

16

is positioned on the tailcone

64

within a cowl

68

. A test bulkhead

70

is positioned on the countermeasure

62

at the other end. Test bulkhead

70

has a clamp

72

positioned thereon. As in the other embodiment, cable

24

extends from the countermeasure to provide power and control instructions.

Countermeasure

62

is held within hardware

60

by clamp

72

and slotted fixtures

74

. Clamp

72

surrounds an intermediate base pipe

76

and joins bulkhead

70

thereto. Intermediate base pipe

76

is joined to base pipes

78

by unions

80

threaded on either end of the intermediate base pipe

76

. Base pipes

78

are joined to the base ends of sliding pipes

82

.

Slotted fixtures

74

are rigid tubes each having a slot

84

formed longitudinally at the end thereof. A tightening bolt

86

is positioned through an aperture formed in the slotted part of each slotted fixture

74

for allowing the slot

84

to be tightened or loosened. Slots

84

are sized to retain countermeasure fins

66

. Slotted fixtures

74

are joined to middle support pipes

88

by unions

80

threaded between fixtures

74

and pipes

88

. Middle support pipes

88

are joined to the middle of sliding pipes

82

.

Sliding pipes

82

are further maintained in parallel relation to one another by an upper pipe

90

joined to the upper ends of sliding pipes

82

. Sliding pipes

82

are sized to slide along cables

48

a

and

48

b

while maintaining the countermeasure

62

in a vertical position. This embodiment allows countermeasure

62

to be easily removed from test fixture

62

by detaching unions

80

.

Based on the foregoing, it can be seen that the present invention provides an apparatus which facilitates the testing of the hovering ability of a countermeasure device. By only requiring that the tailcone portion of the countermeasure device be tested, which portion is solely responsible for providing the hovering capabilities of the countermeasure device, the testing can be performed in a smaller volume of water with less instrumentation and reduced power requirements.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept. Accordingly, the invention is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.