US3926137A

US3926137A - Deep ocean parachute release

Info

Publication number: US3926137A
Application number: US555012A
Authority: US
Inventors: Norman F Johnson
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1975-03-03
Filing date: 1975-03-03
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16

Abstract

A drogue chute is used to extend a long line transducer array in the water as it is being towed in or played out in an ocean current. To avoid problems during a subsequent retrieval of the array, the drogue chute is disconnected. For this reason a release mechanism is interposed between the transducer array and the chute. This release mechanism provides for a nonabrupt separation of the array from the chute''s riser straps. An electronic circuit in the mechanism initiates the separation of a first riser strap to dump the entrained water and next, the second riser to completely sever the chute from the array.

Description

United States Patent [1 1 Johnson Dec. 16, 1975 DEEP OCEAN PARACHUTE RELEASE Norman F. Johnson, San Diego, Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC

22 Filed: Mar.3, 1975 21 Appl. No.2 555,012

[75] Inventor:

[52] US. Cl 114/209; 83/39; 114/235 B;

244/151 B; 307/252 N; 307/252 .1; 340/3 T [51] Int. C1. B63B 21/48 [58] Field of Search 114/209, 221 A, 235 B;

244/150, 151 B; 83/39, 639; 307/252 N, 252 J, 236, 305; 340/3 T, 7 PC [56] References Cited UNITED STATES PATENTS 2,536,682 1/1951 Frieder et a1. 114/209 3,298,347 1/1967 Swain et a1 114/235 B 3,382,377 5/1968 Huffman et a1 307/236 3,484,626 12/1969 Grafham 307/305 3,616,717 11/1971 Jones 114/221 A 3,774,870 ll/l973 Sheffield et a1. 7. 244/151 B 3,800,271 3/1974 Stillman 340/7 PC Primary Examiner-Trygve M. Blix Assistant ExaminerCharles E. Frankfort Attorney, Agent, or FirmRichard S. Sciascia; Ervin F. Johnston; William T. Skeer [57] ABSTRACT A drogue chute is used to extend a long line transducer array in the water as it is being towed in or played out in an ocean current To avoid problems during a subsequent retrieval of the array, the drogue chute is disconnected. For this reason a release mechanism is interposed between the transducer array and the chute. This release mechanism provides for a nonabrupt separation of the array from the chutes riser straps. An electronic circuit in the mechanism initiates the separation of a first riser strap to dump the entrained water and next, the second riser to completely sever the chute from the array.

6 Claims, 5 Drawing Figures US. Pltfiflt Dec. 16, 1975 Sheet 1 of 2 DEEP OCEAN PARACHUTE RELEASE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Usually, hose-like transducer arrays are connected to a drogue chute to extend the array to its full length. When the array is. to be deployed, the supporting ship continues to proceed underway and the drogue chute is cast over the side. The drogue chute fills with water and tows the array from its spool and the array trails behind the ship. The chute also holds the array extended when the supporting craft is at anchor or on-station since the chute will exert a drag in the oceans currents. Thus, it can be seen that a drogue chute can expedite the deployment and positioning of an elongate array. However, during retrieval of the array, the chutes drag becomes excessive. Usually, the chute is considered expendable and it is' disconnected by some interposed mechanism. Unfortunately, when the disconnect would be initiated, a rubber-band-like snap would rebound along the arrays length. The relatively fragile transducers and electronics will become damaged and impair the arrays operability. Even with a static array, i.e., one not being towed, a certain amount of tension exists along the array between a drogue chute and the anchor point. Here again, severing the drogue chute snaps the array. There is'a continuing need in the state of the art for a drogue chute release mechanism which avoids snapping the array and the consequent damage.

SUMMARY OF THE INVENTION This invention is directed to providing an apparatus for releasing a drogue chute from an elongate array extended in tension. A cylindrical housing is connected to the array and a pair of frangible links couple the other end of the housing to the two riser straps of a drogue chute. A pair of guillotine cable cutters, each associated with a separate link, are sequentially initiated first to dump the entrained water mass and secondly to separate the drogue chute from the array in a two step operation.

It is an object of the invention to provide an improved release for a drogue chute.

Another object is to provide a releasing apparatus for initiating a two step release of a drogue chute.

Yet another object is to provide a drogue chute release which does not overly contribute to flow noise.

Yet another object is to provide a fail safe sequential chute release which requires a signal of a first polarity to separate one frangible link and a signal of the opposite polarity to separate the other frangible link.

These and other objects of the invention will become more readily apparent from the ensuing specification when taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric depiction of the invention linking a drogue chute to an elongate array. 1

FIG. 2 is an enlarged isometric view of the invention.

FIG. 3 is a cross-sectional representation of the invention taken generally along lines 3-3 in FIG. 2.

FIG. 4 is an isometric view of a detail of the invention.

FIG. 5 is a schematic diagram of the initiation circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a representative embodiment of a hose-like transducer array 10 reaches from a surface craft 11 and is held extended by a drogue chute 12. Although the array is shown being deployed from a surface craft, other modes of operation can dictate that the array be deployed by a submersible or be trailed from a buoy in the ocean s currents. In any event, a drogue chute is connected at the distal end to act as a drag to extend the array as it is pulled through the water or as it streams in a current. This type of an arrangement provides more satisfactory representations of transmitted and received acoustic energy. Arrays that are allowed to flutter or drift into contorted shape leave much to be desired when signals are to be analyzed.

Usually, the long line array is stored on a large spool. Unwinding the spool releases the array and an attached drogue chute is released. As the chute fills with water, it entrains a water mass and pulls the array in a straight line configuration.

However, a retrieval of the drogue chute does pose some problems. The chute resists being reeled in and the excessive tensile drag may damage the array. In addition, the chute does not lend itself to being pulled through sheaves nor to being wound on the spool.

The solution is to sever the drogue chute from the array by a suitable release mechanism and reel in the array. Yet, because the array is held in tension, severing the chute snaps the array. Particularly, when the array is hundreds or thousands of feet long, this shock can be quite severe. Previous trials have demonstrated that the transducer elements and the associated electronics are damaged during separation.

This invention, a deep ocean drogue release 13, reduces the possibility of, damaging the array during drogue chute disconnect. The drogue chute release mechanism is coupled to two risers 14 extending from drogue chute 12 by a pair of swivels 15. The opposite end of the release mechanism is connected to the array by four cables 16, only three of which are shown in FIG. 3. These cables normally are contained within the array and serve as linking strength members among the transducer elements and the associated electronics.

The release mechanism includes a cylindrically shaped housing 17 which has substantially the same diameter as the array. Such dimensioning provides a cleaner hydrodynamic shape and reduces the problems associated with excessive flow noise.

The interior of the housing is divided into two

cavities

18 and 19 by a separating wall 20. The housing, separating wall and most of the other elements to be discussed are fabricated from a corrosion resistant material such as stainless steel, which possess the strength to bear tensile loads. Cavity 18 faces the trailing end of the transducer array and is closed by a disc-shaped plug 21.

The outside surface of the plug is shaped with four projections 22 which receive the four cables 16 mentioned above, to join the drogue release to the array. The circumferential surface of the plug is provided with an annular groove 23 carrying an O-ring 24 to seal cavity 18 from the surroundings. A snap ring 25 fits into an appropriately shaped groove 26 in the cylindrically shaped housing to hold the plug in place.

An electronic detonation-initiation circuit 27 is dis posed inwardly of the plug and within the confines of cavity 18. The details of the circuit will be discussed later, however it should be noted that only a single pair of

leads

28 and 28" reach from the electronic circuit to the array via a packing member 29.

At the opposite end of the housing a round mounting plate 30 carrying O-ring 31 seals shut a cavity 19. Into the cavity a pair of frangible links 32 reach across from appropriately shaped holes 33 in the mounting plate. O-rings encircle the links shanks to keep water out of the housing interior.

The links are shaped with threaded inner ends 34 for engaging correspondingly shaped threads provided in tapped holes 20a in separating wall 20. The opposite end of each of the frangible links is provided with a threaded recess 35 which mates with correspondingly threaded portions 15a of a ring bolt-swivel combination 15. Thus, the drogue chute is connected to the array via frangible links 32 and housing 17.

Inside cavity 19 a pair of guillotine cutters 36 are sup ported by a pair of nylon clips 37 affixed to the inner surface of mounting plate 30. The cutters are of the type manufactured by I-Iolex, Incorporated, I-Iollister, California, under the code identification number 10640. These cutters are initiated to drive a blade against an anvil and to effect a cutting of a cable placed upon the anvil when a potential is applied to its pair of leads 39.

The guillotine cutters are so arranged on their clips to align smaller diametered portions 38 of the frangible links with the blades of each of the cutters. The smaller diameter portions were machined down to have a tensile strength of about 2,500 pounds. The smaller diametered portions also serve as the weak link in the array and will separate first if some unforeseen excessive force is exerted on the array. The Holex 10640 cutter is sufficient to break the smaller diameter portion. Both pairs of leads 39 are fed through an opening 20b in wall 20 and are coupled to output terminals on the electronic circuit 27.

Part of the essence of this invention resides in the fact that the electronic circuit is initiated twice by signals of opposite polarities across input leads 28 and 28". A signal of one polarity of the input signal actuates one of the guillotine cutters and its associated frangible link is severed. One of the risers 14 is released and the drogue chute slowly dumps its load of entrained water. After a predetermined time, a signal of opposite polarity is fed to electronic circuit 27 via

leads

28 and 28" and the other cutter is actuated. The second actuation severs the other frangible link and the drogue chute is released. By this one-two sequence of cutter initiation there is a new two step release of the drogue chute. There is no sudden snapping of the array, but rather a smooth, two-step removal of the drogues drag. The mechanics of this two-step initiation will become more apparent by a closer look at FIG. 5.

Two identical circuits isolated by

diodes

40 and 41 are used to fire the two cutters independently via only two input leads 28. Apply one polarity across leads 28' and 28" fires one circuit while reversing the polarity of the signal fires the other circuit.

When a positive potential is applied to lead 28' a firing capacitor 42 begins to charge exponentially through diode 41 at a rate determined by the line resistances of leads 28" and 28' and the value of firing capacitor 42. Diode 40 now isolates firing capacitor 43 and its associated circuitry. When the potential on firing capacitor 42 reaches a magnitude as determined by a voltage divider network formed by

resistor

44 and 45, silicone unilateral switch 46 triggers a silicon controlled rectifier 47. This dumps the firing charge stored on firing capacitor 42 to squib 36a of guillotine cutter 36 to fire it.

Applying a positive potential to lead 28" causes the detonation of the other squib 36a in exactly the same manner. A charge begins to exponentially accumulate on firing capacitor 43 at a rate determined by the line resistances of

line

28 and 28" and the value of firing capacitor 43. Diode 41 isolates firing capacitor 42 and its associated circuitry. As the potential on firing capacitor 43 reaches a magnitude as determined by a voltage divider network made up of

resistors

48 and 49, silicone unilateral switch 50 triggers a silicone controlled rectifier 51. This dumps the charge stored on firing capacitor 43 through squib 36a to effect its detonation.

The line resistance of the array used in conjunction with this release mechanism is such that the firing signal need be applied to one of the associated

firing capacitors

42 or 43 for approximately 4 seconds. During this period the accumulated charge reaches a potential on either firing capacitor which is of a sufficient magnitude to actuate its associated

transistor

46 or 50. This time delay provides an added safety feature to prevent accidental firing since it is necessary to apply the firing signal continuously for 4 seconds before either squib is detonated.

A pair of resistors 52 and 53 are protective devices for firing

capacitors

42 and 43, respectively. Since the cavity 18 inside of cylindrically shaped housing 17 is small, the size of the components must be kept down. To help accomplish this all the capacitors chosen are of low voltage ratings. If, for some reason the firing signal were applied across terminals 28' and 28" when the connections to the cutters were inadvertently open, the corresponding charge built on either of the firing

capacitors

42 and 43 would not reach high enough levels to damage them. Thus, the resistors 52 and 53 are included to provide a path to discharge the firing capacitors.

As a final step to ensuring the efficient operation of the aforedescribed electronic circuit, it was fabricated on a printed circuit board and potted in an epoxy-like block sized to fit within cavity 18.

Obviously, many modifications and variations are possible in the light of the above teachings, and it is therefore understood that the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An apparatus for releasing a drogue chute from an elongate array extended in tension comprising:

a housing connected to the array;

means for frangibly coupling the housing to more than one riser of the drogue chute;

means for breaking the frangible coupling means being mounted adjacent thereto; and

means for sequentially initiating the breaking means to effect releasing of the drogue chute in stages thereby preventing the snapping of the elongate array.

2. An apparatus according to claim 1 in which the frangible coupling means are a pair of alloy links each secured to a separate riser and the breaking means are a pair of guillotine cutters each provided with an opening for receiving a separate alloy link therethrough.

3. An apparatus according to claim 2 in which the sequentially initiating means is an electronic circuit formed of components which initiate the detonation of one of the guillotine cutters when an actuation signal of one polarity is fed to it and which initiate the detonation of the other guillotine cutter when an actuation signal of the reverse polarity is fed to it.

4. An apparatus according to claim 3 in which the electronic circuit includes a charging and firing capacitor coupled to each guillotine cutter to provide a delay between the time the actuation signal is fed to the electronic circuit and a guillotine cutter is detonated.

5. An apparatus according to claim 4 in which both guillotine cutters are orthogonally disposed with respect to their associated alloy link to assure the releasing of the drogue chute.

6. An apparatus according to'claim 5 in which the housing is cylindrically shaped having an outer diameter the same as the array to reduce the problems associated with excessive low noise.

Claims

1. An apparatus for releasing a drogue chute from an elongate array extended in tension comprising: a housing connected to the array; means for frangibly coupling the housing to more than one riser of the drogue chute; means for breaking the frangible coupling means being mounted adjacent thereto; and means for sequentially initiating the breaking means to effect releasing of the drogue chute in stages thereby preventing the snapping of the elongate array.

6. An apparatus according to claim 5 in which the housing is cylindrically shaped having an outer diameter the same as the array to reduce the problems associated with excessive low noise.