US3842770A

US3842770A - Variable depth moored sweep

Info

Publication number: US3842770A
Application number: US00851140A
Authority: US
Inventors: E Hedbawny; C Goff; A Holston
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1969-08-07
Filing date: 1969-08-07
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22

Abstract

This apparatus, described in the following specification, comprises an improved system for towing an underwater device, such as a cutter system for severing marine mine mooring cables, in shallow waters. The system includes a depresser to hold the end of the apparatus nearest the tow vessel at a predetermined depth beneath the surface. A second depressor, or otter, at the outboard end of the apparatus is buoyed upward by the action of a float. The float is completely submerged and contains electronic control circuitry to cause the device to control the outboard end of the towed apparatus at either a predetermined depth, or at a predetermined height above the bottom at the selection of the operator. The position of the float is marked by a surface buoy.

Description

[ Oct. 22, 1974 VARIABLE DEPTH MOORED SWEEP [75] Inventors: Edward .1. Hedbawny, Panama City;

Cecil N. Goff, Maitland; Aubrey G. l-lolston, Panama City, all of Fla.

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

[22] Filed: Aug. 7, 1969 [21] Appl. No.: 851,140

[52] US. Cl. 114/20 B, 114/221 A, 114/235 B [51] Int. Cl... F42b 19/04, B63b 17/00, B63b 35/00 Primary Examiner-Samuel Feinberg Assistant ExaminerThomas H. Webb Attorney, Agent, or FirmRichard S. Sciascia; Don D. Doty; William T. Skeer [5 7] ABSTRACT This apparatus, described in the following specification, comprises an improved system for towing an underwater device, such as a cutter system for severing marine mine mooring cables, in shallow waters. The system includes a depresser to hold the end of the apparatus nearest the tow vessel at a predetermined depth beneath the surface. A second depressor, or otter, at the outboard end of the apparatus is buoyed upward by the action of a float. The float is completely submerged and contains electronic control circuitry to cause the device to control the outboard end of the towed apparatus at either a predetermined depth, or at a predetermined-height above the bottom at the selection of the operator. The position of the float is marked by a surface buoy.

10 Claims, 6 Drawing Figures Pmimm 0121221914 842.77 0

sum, 1 tr 4 INVENTORS BY WWI ,13

PATENIEBHBIZZISH Sam M a INVENTORS VARIABLE DEPTH MOORED SWEEP 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 To effectively sever the mooring cable, the cutting implement should strike the mooring cable a sufficient distance below the mine to assure that the cable presents a rigid mechanical obstruction to the path of the cutting implement. Indeep waters, this is accomplished by controlling the dept at which theminesweeping gear is towed. That is, if a moored mine is to be effective against ships of a normal draft, it must be moored at a predetermined depth, and the depth at which the minesweeping gear is to be towed is readily determined in relation to this depth.

Despite the ease at which the optimum towing depth may be determined, the accurate towing of the minesweeping gear at this depth is somewhat difficult. Should the gear contact the mooring cable near the mine, the likeihood that the mine will be pulled beneath the mine sweeping gear and the mooring line remain uncut is increased. If the gear is towed too deep, there is danger that the depressor will ground on the bottom and the sweep gear will become broken and lost. Because of space limitations on minesweeping craft, a very limited number of spares are carried on board. Therefore, the loss of major assemblies-due to the aforementioned grounding frequently requires extensive delays in minesweeping operations until replacement units are obtained.

The sweeping of mines in inshore areas is particularly troublesome, since the ocean depth varies considerably in such areas. The removal of mines in these areas is nonetheless important, since the control of these waters is essential to establish landing areas and the naval support of ground activities. To effectively sweep mines in these areas, it is necessary to repeatedly change the depth at which the minesweeping gear is towed to keep the minesweeping gear at the optimum height to effect severing the mooring lines without grounding the sweep gear.

To change the depth at which the mine sweeping gear of the prior art is towed, the entire apparatus must be recovered and manual adjustments made thereto. This is a time consuming operation and often results in incomplete sweeps, due either to less than optimum depth of towing of the minesweeping gear or to areas not having been traversed by the gear due to navigation inaccuracies encountered during the recovery and restreaming of the gear.

Prior art systems have attempted to overcome the aforesaid problem by placing a remote controlled winch within the float at the outboard end of the tow line. The remote controlled winch is then adjusted from the tow vessel to cause the outboard otter to clear the bottom. Such devices require a communication link to transmit command signals. This control link is subject to detectionand jamming and, often such systems suffer from poor response time.

SUMMARY OF THE INVENTION This invention pertains to an improved system for sweeping moored marine mines and, more particularly, is directed to a system whereby gear for severing the mooring lines of such mines is towed behind a suitable tractor vehicle. In particular, this invention pertains to an improved towed minesweeping system wherein the depth of the towed minesweeping is regulated to maintain predetermined depth or, selectively, to maintain a predetermined height off the bottom. Further, this invention pertains to a minesweeping system having a position control for selectively following the bottom a predetermined distance therefrom including provisions to take the minesweeping gear from the surface to a minesweeping gear to be towed at a predetermined depth with provisions to override said control, so as to avoidcollision-with said bottom. The invention is also, of course, concerned withthe specific elements comprising this system, together with the improved methods of minesweeping made possible thereby.

Accordingly, it is an object of this invention to provide an improved minesweeping system.

A further object of this invention is the provision of an improved minesweeping system effective as a countermeasure against moored mines.

A further object of this invention is the provision of a minesweeping system, including a towed marine vehicle with provisions for selective regulation of either depth or height off the bottom.

A further object of this invention is the provision of a minesweeping system comprising a bottom following vehicle with provisions for automatic take down of the vehicle when it is on the surface subsequent to be launched.

A further object of this invention is the provision of a minesweeping system comprising a towed vehicle having attitude control means effective to regulate the depth of said vehicle to a predetermined value and'having anti-collision control means to prevent the minesweeping gear from striking the bottom.

A further object of this invention is the provision of a minesweeping system having two selectively actuable control circuits for exercising primary control over the minesweeping system, each circuit having secondary control functions in the other circuits control system when said other circuit is selected as the primary control circuit.

A further object of this invention is the provision of a self-controlled, towed float useful in streaming marinegear at predetermined depth beneath the surface of-a body of water or at a predetermined height above the bottom thereof.

Other objects and many of the attendant advantages will be readily appreciated'as the subject invention becomes better understood by reference to the following detailed description,'-when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a minesweeping arrangement of the prior art;

FIG. 2 illustrates, in plan view, an offshore minesweeping operation;

FIG. 3 illustrates the system according to the invention;

FIG. 4 illustrates the controlled float which is a component element of the system of the invention;

FIG. 5 shows a block diagram of the control circuitry of the invention wherein the illustrated position of the switches and relays correspond to the bottom following mode of operation with the float on the surface; and

FIG. 6 is a block diagram of the bottom sounding sonar according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, where the prior art arrangement is illustrated, a tow vessel 11 is shown towing a depressor 12. A mooring cable cutter 13 is attached to vessel 11 by suitable tackle carried by depressor 12. At the outboard end of mooring cable cutter 13 is an otter 14, which holds mooring line cutter l3 depressed in opposition to the buoying action of float 15 that is transmitted via line 16. Otter 14 also diverts the mooring line cutter 13 to one side of the course of tow vessel 11.

When mooring cable cutter 13 contacts a mooring cable 17, one of the individual cutting elements carried by mooring cable cutter 13 severs the mooring cable 17 and separates the moored mine 18 from its anchor 19. The separated moored mine 18 floats to the surface where it may be destroyed or disarmed.

As shown in FIGS. 2 and 3, in the minesweeping system of the invention the tractor vehicle 21 tows a depressor 22 by a cable 23. A cutter carrying cable 24 is also towed by tractor vehicle 21 and is held submerged at its forward end by depressor 22. Conventional cutting implements sever the mine mooriing cables when they are encountered. At the outboard end of the cutter carrying cable 24, an otter 25 diverts the cable to one side and depresses it against the buoyant action of controlled float 26 attached thereto by a short line 27. A buoy 28, which may be a conventional unit, marks the position of controlled float 26 to which it is attached by a suitable light line 29.

FIG. 2 shows, not to scale, the sweeping operation along a coast line 31. As will be readily understood, the bottom in such environments has naturally occurring irregularities therein. Such irregularities are occasioned by streams, such as shown at 32, and promontories, such as shown at 33. It is especially important that the cutting implements carried by line 24 strike the mooring lines at an optimum height above the bottom but equally important that they not foul or ground on the bottom.

Tractor vehicle 21 is illustrated as a conventional displacement type marine vehicle. It should be understood that other types of vehicles may be employed as tractor vehicles. Particularly suited for such assignments are rotary wing aircraft and air cushion vehicles, although other air and water craft may be used as well.

Likewise, buoy 28 may comprise any suitable lightweight device of that type which will not produce excessive drag on the towed system. One such device, which is illustrated, is described in U.S. Pat. No.

The particular mooring cutting implements carried by line 24 may also be state-of-the-art devices. As those versed in minesweeping arts will understand, the prior art devices frequently armed explosive actuated cable cutters. However, good success has been obtained with nonexplosive types as well. The latter types offer the advantage of safety of handling in addition to the obvious advantage of longer unit life. One such type is disclosed in U.S. Pat. application Ser. No. 775,995 filed by William G. Harris, Jr. on Nov. 8, l968 for Mooring Line Cutter System.

The heart of the minesweeping system of the invention is a buoyant submarine vehicle and the control system therefor. In the minesweeping art such submarine vehicles are termed floats, even though they are towed submerged. Referring to FIG. 4 where one embodiment of a submarine vehicle which has met with operational success is shown, it is seen that float 26 comprises a body portion 34 and an empennage 35 attached thereto. I

At the fore and aft ends of body portion 34 are eyes 36. Float 26 is suspended by eyes 36 for storage and maintenance purposes when aboard ship or ashore. The relatively small size of eyes 36 contributes to a stable mounting for the aforementioned storage and maintenance purposes but makes streaming and recovery of float 26 thereby difficult. An enlarged lifting loop 37 is attached to the topside of body portion 34 over the center of gravity to facilitate handling float 26 during streaming and recovery operations.

At the foreward end of body portion 34 on the topside thereof, an elevated tie point 38 extends upwardly therefrom. Lightweight line 29 is attached to the point 38 so as to connect buoy 28 thereto. If desired, a small reel or winch may be mounted within the portion of the faring 39 protecting the point 38 and line 29 attached thereto. In most instances, however, a fixed length of lightweight line 29 suffices to keep buoy 28 within the range necessary to provide marking for the position of float 26 and the reel or winch and the control mechanism therefor are unnecessary.

On either side of the foreward portion of body portion 34, fixed wings 41 are attached. The primary purpose of wings4l is the provision of hydrodynamic lift. The lifting force, naturally, supports line 27 with the attached mooring severing gear. The wings 41 also provide directional stability to float 26. In this capacity they prevent the float from pitching or rolling.

Mounted beneath wings 41 and depending below body portion 34 is a yoke 42. Line 27 is attached to yoke 42 and extends therefrom to otter 25, as previously noted. Yoke 42 is free to move through a considerable angular arc to accommodate positional variations between float 26 and otter 25. The propulsive force transmitted to float 26 are, of course, imparted thereto via line 27 and yoke 42.

It should be noted that the tackle used in streaming Applicants gear, together with the various lines, splices, connectors, etc., are conventional state-of-the-art designs. For example, lines 23, 24, and 27 may be of the self-aligning type illustrated in U.S. Pat. No. 3,368,5l4

issued Feb. 13, 1968, to R. E. Kelly and entitled Symmetrical, Self-Aligning Cable Fairing. Similarly, other state-of-the-art structure may be used to obtain the specific advantages thereof where such substitutions do not interfere with the overall operation of the invention and the disclosed cooperation between the individual elements thereof.

Mounted along the centerline of the float 26 and on the bottom side thereof, a series of ballast weights 43 provide sufficient mass to the assembly to ensure the desired degree of static buoyancy. Ballast weights 43 are made of lead or other dense material and may, if desired, be located within body portion 34 of float 26. In use, the length of cutter carrying line 24 and the number and type of cutters attached thereto may .vary over a wide range. It is therefore more convenient to have ballast weights 32 located on the external portion of float 26 where they may be attached and detached conveniently.

Within the body portion 34 of controlled float 26 is a well 44 for the enclosure of electronic circuit components therein. Well 44 is closed against the entry of water by a hatch cover 45. The flow of water across the float 26 as it is towed is enhanced by making'hatch cover 45 shaped to form an uninterrupted surface with the outer surface of body portion 34. Hatch cover 45 may, of course, be secured by any conventional means deemed appropriate by the skilled artisan making and using the device. Threaded fasteners used with appropriate gasket material have proven satisfactory in use.

Mounted on empennage 35 is an instrument housing 46. A horizontal stabilizer-and controlled elevator assembly 47 are mounted so as to extend outwardly from instrument housing 47 on both sides thereof. The stabilizer portion of assembly 47, as the name implies, helps control pitch and roll of float 26. However, it may also contribute to the hydrodynamic lift of float 26 if it is so designed.

As pertains to the instant invention, the controlled elevator function of assembly 47 is of primary importance. The elevator is controlled to regulate the depth of float 26 as it is towed through the Water. This control action is effected in response to certain condition responsive electronic circuits to be described herein.

Instrument housing 46 provides a watertight enclosure for suitable drive motor mechanism, associated control circuitry, and necessary transmission gearing for moving the elevator surfaces of assembly 47. The motor mechanism is a conventional arrangement. Since a detailed description of the motor is unnecessary to the understanding of the invention, the specific construction thereof is not included herein. Certain electrical aspects of the motor will be described in the discussion of the electronic circuitry.

An electroacoustic transducer 48 is shown mounted at the foreward end of instrument housing 46. The positioning of transducer 48 is a design parameter subject to a considerable degree of choice on the part of the design engineer. In general, it should be located toward the aft end of the float 26 to prevent shading of its emissions therefrom by yoke 42. However, it may be located other than within instrument housing 46, or other than at the forward end thereof. For example, trans ducer 48 may be a piezoelectric line array and, in such instances, may be placed along the bottom of instru-v ment housing 46.

A suitably waterproofed electrical cable 49 connects instrument housing 46, and the electronic components contained therein, to the electrical devices housed within well 44. The exact construction and type of cable employed for this purpose may be regarded as a matter of design choice to a person versed in the electronic instrumentation arts.

The present state-of-the-art of electronic circuitry permits theenclosure of the entire system within instrument housing 46, if desired. In such instances, cable 49 is not required. Floats so modified have the advantage of being convertible to and from surface floats 15 of the prior art type. Further, float service requirements benefit from such an arrangement since instrument housing 46 and the control circuitry contained therein may be stocked, serviced, and shipped separately from the remaining portions of float 26.

Referring now to FIG. 5, a block diagram representation of the control circuitry is shown. A depth selector switch 51 selects a direct current voltage to be fed to a level detector 52 in accordance to the position of a mode switch 53, as will be herein explained. Similarly a bottom height select switch 54 selects one of a plurality of direct current voltages to be fed to level detector in another position of mode switch 53.

Level detector 52 compares the voltage supplied it by one of

switches

51 or 54 with a voltage produced by a corresponding sensor. Depth sensor 55 is one of these sensors and it produces a signal corresponding'to the depth of controlled float 26 beneath the surface of the water. A'variety of conventional pressure responsive devices may be employed in this capacity and, accordingly, no detailed description of such a device is included herein. For the purpose of completeness, it is noted that a switch mechanism actuated by an aneroid pressure sensing mechanism will perform satisfactorily in applicants invention for depth sensor 55.

The other sensor feeding a sensed signal to level detector 52 is bottom sounder 56. Bottom sounder 56 is a height off bottom sonar which will be described in greater detail in conjunction with FIG. 6. It is sufficient for the purposes of description of FIG. 5 to note that bottom sounder 56 provides an electrical signal which is an electrical analog of the range to the bottom obtained by echo ranging techniques. Depth sensor 55 also feeds an output signal, an electrical analog of the depth beneath the surface, to a rate detector circuit 57. This signal is fed directly without going through mode switch 53. An electrical analog of the time rate of change of the detected depth beneath the surface is produced by rate detector 57 in response to the output of depth sensor 55. Rate detector 57 may be any suitable conventional time rate of change detector circuit responsive to signals of both positive and negative polarity.- Y

The output from rate detector circuit 57, together with the output from level detector 52, is fed to a summing amplifier 58. Summing amplifier 58 combines the two input signals into a single output signal of appropriate magnitude and polarity to be utilized by a motor and drive circuit 59.

Motor and drive circuit 59 comprise a conventional arrangement of DC motor, gear transmission, and limit switches to interrupt the operation of the motor at certain predetermined points in the operation thereof. The direction of the rotation of the motor is determined by summing amplifier 58 in accordance with the polarity of the electrical energy supplied the motor thereby. The magnitude of the electrical signal supplied motor and drive circuit 59 governs the speed of rotation of the motor and, therefore, the speed at which the elevator of assembly 47 is moved to control the motion of float In addition to supplying an output signal to rate detector 57, depth sensor 55 has its output signal fed to a takedown circuit 61. This circuit is a threshhold circuit and produces an output when depth sensor 55 has an output corresponding to a predetermined depth of float 26. This output energizes a relay 62 to cause contacts 62a and 62b to assume their alternate position from that illustrated in FIG. 5. The purpose of this operation of relay 62, from which the name takedown circuit is derived, will be explained in conjunction with the operation of the device.

Another secondary control circuit, anticollision circuit 63, provides secondary control to prevent depressor-otter or cutter carrying line 24 from grounding. Anticollision circuit 63 is shown as comprising a bistable switch 73 controlled by two

comparator circuits

72 and 74. Comparator 72 is connected so as to have an input from bottom sounder 56 and another input from bottom height select switch 54 which serves as a standard to which the input from bottom sounder 56 is compared. Comparator 74 is connected to depth select switch 51 for receipt of a standard signal therefrom and to depth sensor 55 for receipt of a depth analog signal therefrom. The input of comparator 74 preferably includes a divider network to reduce the depth signals magnitude by a predetermined amount, as will be explained in the description of the mode of operation.

The outputs of

comparators

72 and 74 are connected to the input of bistable switch 73. Bistable switch 73 may be any of several known solid state conduction devices. The conduction state of bistable switch 73 is alternately changed by the outputs of

comparators

72 and 74 as will be more fully explained in connection with the description of the mode of operation. In one conduction state bistable switch energizes relay 64 to move contacts 64a and 64b to their alternate position from that illustrated in FIG. 5.

When energized, relay 64 changes the connections feeding the input signals to level detector 52. The outputs of depth select switch 51 and depth sensor 55 to level detector 52 are removed and the outputs of bottom height switch 54 and bottom sounder 56 are substituted therefor. This effectively changes the circuitry to that previously outlined in describing the bottom following position of mode switch 53.

As noted in the foregoing description of FIG. 5, the individual circuits, identified by blocks therein, are conventional circuits or hardware with the exception of bottom sounder 56. As disclosed above, bottom sounder 56 is a height of bottom sonar system. This circuit continuously echo ranges the bottom and provides an output signal which is proportional to the height of the float 26 above the bottom.

Referring now to FIG. 6, it is seen that bottom sounder 56 comprises a transmitter 65 which feeds a burst of electrical energy to electroacoustic transducer 48. The electrical energy is converted by electroacoustic transducer 48, which may be a piezoelectric device, for example, to acoustic frequency compressional wave energy. The compressional wave energy impinges the bottom and produces an echo return therefrom which is returned to transducer 48.

An echo signal is produced by transducer 48 in response to the echo return of the compressional wave energy and is fed, via appropriate transmit receive circuitry, to an amplifier 66. The echo signal is increased in power level by the action of amplifier 66 and is fed to a detector 67. Detector 67 is a conventional envelope detector and produces an output having a sharp rise in level corresponding in time of occurrence to the receipt of a target return.

The output of detector 67 is differentiated by differentiator 68 to which it is supplied. Differentiator 68 produces a sharp spike signal corresponding to the leading edge of echo signal. The differentiated signal is fed to a bistable multivibrator 69.

Simultaneously with the feeding a burst of electrical energy to transducer 48, transmitter feeds a synchronizing electrical pulse to bistable multivibrator 69. Upon receipt of this signal, bistable multivibrator 69 assumes a first conduction state, the flip state. When the spike pulse from differentiator 68 is applied, bistable multivibrator 69 assumes a second, or flop, conduction state.

As will be readily recognized by those familiar with the electronic arts, the operation of bistable multivibrator 69 is conventional. The length of time that bistable multivibrator 69 is in the first, or flip," conduction state bears a direct, predictable relation to the range of the reflecting body returning the compressional wave energy, i.e., the bottom. This time relationship is converted to a voltage analog by the action of integrator 71 to which the output of bistable multivibrator 69 is connected. Integrator 71 produces an output causing float 26 to surface when bottom sounder 56 receives no bottom return.

From the foregoing description, a person who is skilled in the moored minesweeping and familar related arts can obtain a complete structural understanding of applicants new and useful combination of elements. Except where noted, the structure and circuitry of the device are of conventional construction. Accordingly, known equivalent structure may, at the option of the builder, be incorporated herein for performance of the equivalent function as will be more fully understood in the following description of the mode of operation.

MODE OF OPERATION The preferred mode of operation of the aforedescribed components comprising the moored minesweeping system of the invention will now be described.

Upon entering waters believed to contain moored marine mines, the float 26 is made ready to be streamed by suitable crane and other handling gear on board tractor vehicle 21. Lifting loop 37 facilitates the prelaunch preparation of float 26. While on board tractor vehicle 26, hatch cover 45 is removed, the control circuitry is activated, and the hatch cover 45 secured. Prior to launch buoy 28 is made fast to float 26 by securing lightweight line 29 to tie point 38. Cable 27 is next made fast to yoke 42 to suspend otter 25 therebeneath.

Buoy 28, float 26, and otter 25 are lowered away and cable 24, carrying cutters therewith, is payed out. Toward the bitter end of cable 24, depressor 22 is attached by suitable tackle and streamed together with cable 23 attached thereto.

Under the influence of depressor 22 and otter 25, cable 24, including the cutters carried thereby, is deplaoyed to the side of tractor vehicle 21 and beneath the surface of the water. The depth to which otter 25 carries the distal end of cable 24 is regulated by the lifting action of float 26. In turn, the controlling action of the elevator mechanism portion of assembly 47 determines the amount of lift produced by float 26 as it is towed by tractor vessel 21.

Assuming that mode switch 53 is set to the illustrated (FIG. bottom following mode, the control mechanism operates to keep float at a constant height from the bottom. The position of mode switch 53 obtained by counterclockwise rotation from the position shown in FIG. 5 produces a depth regulated mode of operation. In the depth regulated mode of operation, the control system functions to keep float 26 at a constant depth beneath the surface of the water.

As previously noted, the illustration of the control circuitry shown in FIG. 5 is shown in the bottom following mode, just subsequent to launch, with controlled float 26 on the surface or just beneath the surface. Under these circumstances, it is diff cult for bottom sounder 56 to acquire the bottom reflection signal. Because of this initial inability of bottom sounder 56 to supply a reliable control signal, this initial phase of the bottom following mode of operation is under the control of depth select switch 51 and depth sensor 55.

A voltage analog of a predetermined depth of fed level detector 52 via relay contacts 62a and a first section of mode switch 53. Depth sensor 55 produces an electrical signal corresponding to the zero depth of float 26. This sensed signal is'fed, via relay contacts 62b and a second section of mode switch 53, tolevel detector 52.

Level detector 52 compares the two signals and produces a control signal of the proper polarity to drive the motor portion of motor and control circuit 59 in a direction to effect an alteration of the angle of elevator causing float 26 to dive. This signal is amplified by summing amplifier 58 prior to being fed to motorand control circuit 59.

The sensed depth signal from depth sensor 55 is also fed to a rate detector 57. An electrical signal which is an analog of the time rate of change in the vertical direction, i.e., vertical velocity, is produced by rate de tector 57. This rate signal, which is of the opposite polarity for descent and ascent, 'is fed to summing amplifier 58 where it provides a partial cancellation, or damping, of the control signal fed by level detector 52. This serves to improve stability of the float and minimizes violent or abrupt control operations. If left uncorrected, these abrupt changes produce undesirable waves and tensions in the line 24.

The sensed depth signal is also fed from depth sensor 55 to take down circuit 61. When the sensed depth signal exceeds a predetermined value, takedown circuit energizes relay 62, thereby placing contacts 62a and 62b in the alternate position from that illustrated.

The value of the detected depth signal necessary to trigger takedown circuit'6l is predetermined in accordance with the depth at which bottom sounder 56 can acquire the bottom reflection. This may conveniently be adjusted to'correspond to different operating conditions, but it is not ordinarily a front panel" control. That is, it need not be adjusted for each successive use but only when operating conditions change sufficiently height select switch 54 and. bottom sounder 56. The' height select switch 54 provides a reference voltage corresponding to the height off the bottom at which it is desired to position float 26. The bottom sounder 56, as previously explained, provides level detector 52 with a signal voltage analog of the height off the bottom. Level detector 52 functions in the same manner as in the case of the depth signals to produce a control signal to regulate the movement of float 26 about this selected height.

It will be observed that the energization of relay 62 has no effect upon the circuitry of rate detector 57 which continues to receive detected depth signals from depth sensor 55. The rate detector 57 together with depth sensor continues to function as a control during the bottom following mode of operation. This control stabilizes float 26 as tractor vehicle 21 tows it over bottom discontinuities.

This stabilization afforded by the aforediscussed circuitry materially assists bottom sounder 56 in maintaining echo ranging contact with the bottom. Should bottom sounder 56 lose contact with the bottom, the fail safe provision of no return signal corresponding to the maximum rise signal causes float 26 to rise to the surface where it may be recovered.

Takedown circuit 61 may be advantageously designed to function as a one shot device in order to prevent float from porpoising, that is alternately submerging and surfacing, under the combined provisions of takedown circuit 61- and the failsafe output of bottom sounder 56. This provision may be made internal to the threshholder circuitry, or, if desired, may be an electrical or mechanical latching mechanism used in conjunction with relay 62. The interlocking connections may be incorporated. in the power switching mechanism or in the lifting loop 37, as will be readily understood by those versed in the arts.

In circumstances where tractor vehicle 21 is to come to a stop from time-to-time, the construction of takedown circuit as a one shot device is undesirable. Under such stationary conditions of tractor vehicle 21, the small net positive buoyancy of the system causes float 26 to surface. When tractor vehicle 21 gets underway again, it is desirable to have takedown circuit 61 functioning to return float 26 to effective sounding range again. This dual requirement may be incorporated by interrupting the one shot circuitry, as will be understood by the proficient artisan.

This completes the discussion of the mode of operation of Applicants invention in the bottom following mode. From the foregoing discussion, one sees that the float 26 will be operative in this mode to follow the bottom at a predetermined height thereabove. The regulated trajectory of float 26 keeps cable 24 at the predetermined optimum height in relation to the mooring hardware of marine mines to effect the severing thereof.

To selectively adapt the system to a depth following mode of operation, mode switch 53 is placed in the alternate' position, corresponding to counterclockwise rotation as seen in FIG. 5. In this position, the output of depth select switch 51 and depth sensor 55 are routed to level detector 52 via relay contacts 64a and 64b. Depth select switch 51 feeds a voltage analog of a predetermined depth at which it is desired to operate float 26. The circuit functions as previously explained with level detector 52 and rate detector 57 responding to the signals from the depth select switch 51 and depth sensor 55 to control the float at a predetermined depth beneath the surface of the water.

When operating in the depth following mode, a danger exists that otter 25 or line 24 will ground on a bottom irregularity. To prevent this undesirable eventuality from occurring, anticollision circuit 63 interrupts the depth following control mode when the bottom is approached within a predetermined distance and changes the control to bottom following. Depth following control is reestablished when float 26 attains a depth greater than the set depth by a predetermined amount.

To effect this change of control function, the output 7 from bottom sounder 56 is supplied to comparator 72,

a component part of anticollision circuit 63, where its value is compared to a reference voltage which, in the preferred embodiment, is supplied by bottom height select switch 54. An output signal is generated when the relative magnitude of the two signals corresponds to the bottom lying at a range less than that selected by the bottom height select switch.

The output from comparator 72 is fed to bistable switch 73. Upon the receipt of the output signal from comparator 72, bistable switch 73 changes its conduction state such as to energize relay 64. The relay remains energized until bistable switch 73 receives a signal from comparator 74 restoring itto its initial conduction state.

Comparator 74 provides the restoring output when the output of depth sounder 55 exceeds by a predetermined amount the output of depth select switch 51, both of these signals comprising the input signals thereto. The establishment of the predetermined amount by which the detected depth signal exceeds the selected signal may be accomplished by a simple divider network, if desired. When bistable switch 73 resumes its initial conduction state, relay 64 is deenergized.

It is energized condition relay 64 moves contacts 64a and 64b to the alternate position than that illustrated in FIG. 5. In this alternate position, contacts 64a and 64b disconnect depth switch 51 and depth sensor 55 from level detector 52 and connect bottom height select switch 54 and bottom sounder 56 therefor. The control circuit functions as a bottom follower until the depth obtained by float 26 exceeds the depth set on depth select switch 51 by a predetermined amount, as noted above.

Therefore it is seen that when the primary mode of operation as determined by the setting of mode switch 53 is depth following, the bottom sounding circuitry continues to serve as a secondary control function.

It should be understood that the limits of operation of the device are adjustable to meet a variety of operational circumstances and it is in this light that the term predetermined as it applies to the limits of operation is to be understood. For example, to avoid fouling the gear on the bottom, it is necessary to recognize that cable 24 has a sag which is dependent on the length thereof and the type of cable severing hardware carried thereby. This sag distance must be taken into consideration, as well as the depth required to clear otter 25. Similarly, the overall control system is of the cybernetic type which hunts about a given control setting the amount of variation is a function of the sensitivity and response characteristics of the component parts of the system. This response hunt range must be taken into consideration in the setting of the limits of the point at which relay 64 functions to return the control of float 26 to the depth following mode if rapid hunting or relay chatter between the modes is to be eliminated.

The foregoing description of the preferred embodiment of the invention taken together with the'mode of operation thereof and the appended claims constitute a complete disclosure of the invention. However, it should be noted that modification of the details of the device will suggest themselves to persons proficient in the design and construction of ocean science instrumentation gear. Examples of such modification would be the ganging of

switches

51 and 54 to provide a single front panel control for both regulation circuits. For extreme lengths of cutting line, a second controlled float may be employed midway therealong. Such modifications are considered to be logical extensions of the teachings of applicants invention within the normal scope of technical expertise of the proficient marine science engineer.

Although Applicants invention has been described in connection with its uses in marine mine countermeasure systems, it should be clear that the system and components thereof have applicability in other arts' where apparatus must be streamed from marine tow vehicles. Underwater Seismology and piscatology, in particular, are arts 'where applicants invention may be practiced and utilized to an advantage. Only small, obvious alterations to applicants structure to enable employment in these arts.

Similarly, it should be apparent that the control system of Applicants could be utilized in other submarine vehicles where similar control of the vehicles running depth is desired. This could include, of course, manned as well as unmanned vehicles.

From the foregoing, it is seen that applicants invention provides a minesweeping system which may be set in accordance with the prevailing conditions to regulate the depth of the cutting system when under tow. The system will function as a bottom following or depth controlled system. In either mode of operation the control circuitry of the other mode serves as a secondary control. The system disclosed is seen to meet the objects of invention, as outlined herein, and to constitute an unobvious, meritorious advance in the marine arts. Further, the invention provides a significant advance in the marine engineering arts which is unobvious to a person of ordinary proficiency without the benefit of the teachings contained herein but, which may be practiced by such an artisan having the benefit of these teachings.

What is claimed is:

1. A controlled submarine vehicle adapted for movement within an aqueous medium having upper and lower boundary surfaces, said vehicle comprising in combination: a

a body portion;

hydrodynamic lift producing means attached to said body portion in such a manner as to produce a dynamic force in response to movement through said aqueous medium such as to act on said body portion in a direction generally at right angles to the direction of travel thereof for causing movement between said boundary surfaces;

attitude control means attached to said body portion in such a manner as to alter the angular attitude thereof relative to its direction of movement, so as to alter the angle of attack between said hydrodynamic lift producing means and the aqueous medium for altering the dynamic lift produced thereby; and

control circuit means carried within said submarine vehicle and effectively attached to said attitude control means for movement thereof in response to detected changes of position with respect to a selected one of said upper and lower boundary surfacesand additionally responsive to detected positional changes in excess of a predetermined amount with respect to the nonselected one thereof for self-contained guidance of said controlled submarine vehicle in said aqueous medium.

2. A controlled vehicle according to claim 1 in which said control circuit means includes:

pressure responsive means adapted to generate a signal related to the distance between said controlled vehicle and the upper boundary surface of said aqueous medium; r

rate detection means connected to said pressure responsive means for receipt of said distance related signal therefrom and adapted to produce a signal related to the time rate of change thereof; and

summing means effectively connected to said prssure responsive means for receipt of said distance related signal therefrom and connected to said rate detection means for receipt of said rate related signal therefrom and adapted to generate a control signal in response to said received signals.

3. A controlled vehicle according to claim 1 in which said control circuit means includes:

pressure responsive means adapted to generate a signal related to the distance between said controlled vehicle and the upper boundary surface of said aqueous medium;

depth selector means for selecting a signal related to a predetermined distance from said selected parameter at which it is desired to position said controlled vehicle;

level detector means connected to said pressure responsive means and to said depth selector means for receipt of said distance signal and said selected signal therefrom and adapted to produce a difference signal related to the difference in magnitude of said distance signal'and said selected signal;

rate detection means connected to said pressure responsive means for receipt of said distance signals therefrom and adapted to produce a signal related to the time rate of change thereof; and

summing means connected to said. level detector means and said rate detector means for receipt of said difference signal and said time rate signal therefrom and adapted to generate a control signal in response to said received signals.

4. A controlled vehicle according to claim 1 in which said control circuit means comprises:

pressure responsive means to generate a first electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium;

sounding means to generate a second electrical signal related to the position of said vehicle with respect to said lower boundary surface of said aqueous medium;

level detector means to generate a control electrical signal in response to either of said first or second electrical signals;

selector means connected in electrical circuit relationship with said level detector means, said pressure responsive means, and said sounding means and being manually adjustable so as to effectively connect said level detector means to either said pressure responsive means or to said sounding means for receipt of said first and second electrical signals therefrom;

anticollision means connected to said sounding means for receipt of said second electrical signals therefrom and effectively connected to said level detector means for supplying said second electrical signals thereto instead of said first electrical signals when said selector means in in the position to connect said level detector means to said pressure responsivemeans and when said second electrical signal corresponds to the approach of said controlled vehicle within a predetermined distance from said lower boundary surface; and

takedown means connected to said pressure responsive means for receipt of said first electrical signals therefrom and effectively connected to said level detector means for supplying said first electrical signal thereto instead of said second electrical signal when said selector means is adjusted to connect said level detector means to said sounding means for receipt of said second electrical signal therefrom and when said controlled vehicle is within a predetermined distance of said upper boundary surface of said aqueous medium.

5. A controlled vehicle according to claim 1 in which said control circuit means comprises:

pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium; I

depth selector means for selecting a first reference electrical signal related to the desired operational distance between said vehicle and said upper boundary surface;

sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said lower boundary surface;

bottom height selector means for selecting a second reference electrical signal related to the desired operational distance between said vehicle and said lower boundary surface;

level detector means generating a control electrical signal related tov the relative magnitudes of detected electrical signals and reference electrical signals fed thereto;

mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; and

anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second de tected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance.

6. A controlled vehicle according to claim 1 in which said control circuit means comprises:

pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium;

depth selector means for selecting a first reference electrical signal related to the desired operational distance between said vehicle and said first boundary surface;

sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said second boundary surface;

level detector means generating a control electrical signal related to, the relative magnitudes of detected electrical signals and reference electrical signals fed thereto;

mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means;

anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance; and

takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference sig- 6 nals when said vehicle IS within a predetermined distance with respect to said upper boundary surface.

7. A controlled vehicle according to claim 1 in which said control circuit means comprises:

sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said lower boundary surface,

level detector means generating a control electrical signal related to the relative magnitudes of detected electrical signals and reference electrical signals fed thereto;

mode selector means connected in electrical circuit anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said second boundary surface within a predetermined distance, said anticollision means also connected to said pressure responsiye means and to said depth selector means for receipt of said first detected and reference signals therefrom and effective to terminate the substitution of said second detected and reference signals, so as to revert to the feeding of said first detected and reference signals to said level detector means, when said vehicle exceeds the depth selected by said depth selector means by a predetermined amount; and

takedown means connected to said pressure respon- 8. A controlled vehicle according to claim 1 in which said control circuit means comprises:

pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to 21 upper boundary surface of said aqueous medium;

mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and

said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means;

anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said, first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance, said anticollision means also connected to said pressure responsive means and to said depth selector means for receipt of said first detected and reference signals therefrom and effective to terminate the substitution of said second detected and reference signals; so as to revert to the feeding of said first detected and reference signals to said level detector means, when said vehicle exceeds the depth selected by said depth selector means by a predetermined amount;

takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference signals when said vehicle is within a predetermined distance with respect to said upper boundary surface,

rate responsive means connected to said pressure re sponsive means for receipt of said first detected signal therefrom and producing an output signal related to the time rate of change of said first de-' tected signal; and summing means connected to said level detector means for receipt of said control slgnal therefrom and connected to said rate responsive means for receipt of said rate signal therefrom and generating a composite signal related to the sum of said control and rate signals. 9. A controlled vehicle according to claim 1 in which said control circuit means'comprises:

mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depthselector means, and said sounding means and said bottom height selec- 'tor means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; 7

anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and'effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance, said anticollision means also connected to said' pressure responsive means and to said depth selector means for receipt of said first detected and reference signals therefrom and effective to terminate the substitution of said second detected and reference signals, so as to revert to the feeding of said first detected and reference signals to said level detector means, when said vehicle exceeds the depth selected'by said depth selector means by a predetermined amount;

takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference signals when said vehicle is within a predetermined distance with respect to said upper boundary surface;

rate responsive means connected to said pressure responsive means for receipt of said first detected signal therefrom and producing an output signal related to the time rate of change of said first detected signal;

summing means connected to said level detector means for receipt of said control signals therefrom and connected to said rate responsive means for receipt of said rate signals therefrom and generating a composite signal related to the sum of said control and rate signals; and

motor means electrically connected to said summing means for receipt of said composite signal therefrom and operative so as to be electrically driven thereby and connected mechanically to said attitude control means.

10. A countermeasure system for concealed explosive means which are attached to mooring lines so as to be moored within an aqueous medium having an upper and lower boundary surface, said system comprising:

tractor vehicle means operating proximate to said upper boundary of said aqueous medium and providing propulsive force for said system;

tow line means attached at its bitter end to said tractor vehicle means; depressor means attached to said tow line means at the distal end thereof for providing a dynamic force as a result of the propulsive force imparted thereto by said tractor vehicle via said towline means to effect the submergence within the aqueous medium of said distal end thereof; cutter line means attached to said tractor vehicle at the bitter end thereof and attached to said depressor means at an intermediate point therealong to extend beyond said depressor means;

cutting means attached to said cutter line at intervals along said portion thereof extending beyond said depressor means;

otter-depressor means attached to said cutter line at the distal end thereof and responsive to the propulsive force transmitted thereto by said cutter line to 20 deploy said cutter line in a laterally protrusile relationship to the course of said tractor vehicle and submerged within said aqueous medium; and

float vehicle means attached to said otter-depressor means for buoying said otter-depressor and the cutter line carried thereby to a controlled position within said aqueous medium predetermined as an optimum intercept point of said mooring lines, said float vehicle means comprising;

a body portion;

hydrodynamic lift producing means attached to said body portion for producing a dynamic force as said float is towed through said aqueous medium to oppose the depressing action of said otter-depressor means;

attitude control means effectively attached to said body portion for changing the angular attitude thereof relative to the direction of towing movement thereof so as to effectively alter the angle between said lift producing means and the direction of relative flow of the aqueous medium;

pressure responsive means responsive to the pressure of the aqueous medium at the float level to generate a signal related to the distance between said float and said upper boundary surface;

sounding means generating a signal related to the distance between said float and said lower boundary surface; and 7 control circuit means within said body portion and connecting said pressure responsive means and said sounding means to said attitude control means for selective operation thereof by a selected one of the signal outputs of said pressure responsive means or said sounding means. addition, the heat output per unit of combusted gas is very good.

Claims

1. A controlled submarine vehicle adapted for movement within an aqueous medium having upper and lower boundary surfaces, said vehicle comprising in combination: a body portion; hydrodynamic lift producing means attached to said body portion in such a manner as to produce a dynamic force in response to movement through said aqueous medium such as to act on said body portion in a direction generally at right angles to the direction of travel thereof for causing movement between said boundary surfaces; attitude control means attached to said body portion in such a manner as to alter the angular attitude thereof relative to its direction of movement, so as to alter the angle of attack between said hydrodynamic lift producing means and the aqueous medium for altering the dynamic lift produced thereby; an control circuit means carried within said submarine vehicle and effectively attached to said attitude control means for movement thereof in response to detected changes of position with respect to a selected one of said upper and lower boundary surfaces and additionally responsive to detected positional changes in excess of a predetermined amount with respect to the nonselected one thereof for self-contained guidance of said controlled submarine vehicle in said aqueous medium.

2. A controlled vehicle according to claim 1 in which said control circuit means includes: pressure responsive means adapted to generate a signal related to the distance between said controlled vehicle and the upper boundary surface of said aqueous medium; rate detection means connected to said pressure responsive means for receipt of said distance related signal therefrom and adapted to produce a signal related to the time rate of change thereof; and summing means effectively connected to said prssure responsive means for receipt of said distance related signal therefrom and connected to said rate detection means for receipt of said rate related signal therefrom and adapted to generate a control signal in response to said received signals.

3. A controlled vehicle according to claim 1 in which said control circuit means includes: pressure responsive means adapted to generate a signal related to the distance between said controlled vehicle and the upper boundary surface of said aqueous medium; depth selector means for selecting a signal related to a predetermined distance from said selected parameter at which it is desired to position said controlled vehicle; level detector means connected to said pressure responsive means and to said depth selector means for receipt of said distance signal and said selected signal therefrom and adapted to produce a difference signal related to the difference in magnitude of said distance signal and said selected signal; rate detection means connected to said pressure responsive means for receipt of said distance signals therefrom and adapted to produce a signal related to the time rate of change thereof; and summing means connected to said level detector means and said rate detector means for receipt of said difference signal and said time rate signal therefrom and adapted to generate a control signal in response to said received signals.

4. A controlled vehicle according to claim 1 in which said control circuit means comprises: pressure responsive means to generate a first electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium; sounding means to generate a second electrical signal related to the position of said vehicle with respect to said lower boundary surface of said aqueous medium; level detector means to generate a control electrical signal in response to either of said first or second electrical signals; selector means connected in electrical circuit relationship with said level detector means, said pressure responsive means, and said sounding means and being manually adjustable so as to effectively connect said level detector means to either said pressure responsive means or to said sounding means for receipt of said first and second electrical signals therefrom; anticollision means connected to said sounding means for receipt of said second electrical signals therefrom and effectively connected to said level detector means for supplying said second electrical signals thereto instead of said first electrical signals when said selector means in in the position to connect said level detector means to said pressure responsive means and when said second electrical signal corresponds to the approach of said controlled vehicle within a predetermined distance from said lower boundary surface; and takedown means connected to said pressure responsive means for receipt of said first electrical signals therefrom and effectively connected to said level detector means for supplying said first electrical signal thereto instead of said second electrical signal when said selector means is adjusted to connect said level detector means to said sounding means for receipt of said second electrical signal therefrom and when said controlled vehicle is within a predetermined distance of said upper boundary surface of said aqueous medium.

5. A controlled vehicle according to claim 1 in which said control circuit means comprises: pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium; depth selector means for selecting a first reference electrical signal related to the desired operational distance between said vehicle and said upper boundary surface; sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said lower boundary surface; bottom height selector means for selecting a second reference electrical signal related to the desired operational distance between said vehicle and said lowEr boundary surface; level detector means generating a control electrical signal related to the relative magnitudes of detected electrical signals and reference electrical signals fed thereto; mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; and anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance.

6. A controlled vehicle according to claim 1 in which said control circuit means comprises: pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium; depth selector means for selecting a first reference electrical signal related to the desired operational distance between said vehicle and said first boundary surface; sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said second boundary surface; bottom height selector means for selecting a second reference electrical signal related to the desired operational distance between said vehicle and said lower boundary surface; level detector means generating a control electrical signal related to the relative magnitudes of detected electrical signals and reference electrical signals fed thereto; mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance; and takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference signals when said vehicle is within a predetermined distance with respect to said upper boundary surface.

7. A controlled vehicle according to claim 1 in which said control circuit means comprises: pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium; depth selector means for selecting a first reference electrical signal related to the desireD operational distance between said vehicle and said upper boundary surface; sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said lower boundary surface, bottom height selector means for selecting a second reference electrical signal related to the desired operational distance between said vehicle and said lower boundary surface; level detector means generating a control electrical signal related to the relative magnitudes of detected electrical signals and reference electrical signals fed thereto; mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said second boundary surface within a predetermined distance, said anticollision means also connected to said pressure responsive means and to said depth selector means for receipt of said first detected and reference signals therefrom and effective to terminate the substitution of said second detected and reference signals, so as to revert to the feeding of said first detected and reference signals to said level detector means, when said vehicle exceeds the depth selected by said depth selector means by a predetermined amount; and takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference signals when said vehicle is within a predetermined distance with respect to said first boundary surface.

8. A controlled vehicle according to claim 1 in which said control circuit means comprises: pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to a upper boundary surface of said aqueous medium; depth selector means for selecting a first reference electrical signal related to the desired operational distance between said vehicle and said upper boundary surface; sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said lower boundary surface; bottom height selector means for selecting a second reference electrical signal related to the desired operational distance between said vehicle and said lower boundary surface; level detector means generating a control electrical signal related to the relative magnitudes of detected electrical signals and reference electrical signals fed thereto; mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance, said anticollision means also connected to said pressure responsive means and to said depth selector means for receipt of said first detected and reference signals therefrom and effective to terminate the substitution of said second detected and reference signals, so as to revert to the feeding of said first detected and reference signals to said level detector means, when said vehicle exceeds the depth selected by said depth selector means by a predetermined amount; takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference signals when said vehicle is within a predetermined distance with respect to said upper boundary surface, rate responsive means connected to said pressure responsive means for receipt of said first detected signal therefrom and producing an output signal related to the time rate of change of said first detected signal; and summing means connected to said level detector means for receipt of said control signal therefrom and connected to said rate responsive means for receipt of said rate signal therefrom and generating a composite signal related to the sum of said control and rate signals.

9. A controlled vehicle according to claim 1 in which said control circuit means comprises: pressure responsive means generating a first detected electrical signal related to the position of said vehicle with respect to said upper boundary surface of said aqueous medium; depth selector means for selecting a first reference electrical signal related to the desired operational distance between said vehicle and said upper boundary surface; sounding means generating a second detected electrical signal related to the position of said vehicle with respect to said lower boundary surface; bottom height selector means for selecting a second reference electrical signal related to the desired operational distance between said vehicle and said lower boundary surface; level detector means generating a control electrical signal related to the relative magnitudes of detected electrical signals and reference electrical signals fed thereto; mode selector means connected in electrical circuit with said level detector means, said pressure responsive means and said depth selector means, and said sounding means and said bottom height selector means and being manually adjustable to a first position to feed said first detected and said first reference signals to said level detector means, or to a second position to feed said second detected and said second reference signals to said level detector means; anticollision means connected to said sounding means and to said bottom height selector means for receipt of said second detected electrical signal and said second reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said first position and effective to substitute said second detected and reference signals for said first detected and reference signals when said vehicle approaches said lower boundary surface within a predetermined distance, said anticollision means also connected to said pressure responsive means and to said depth selector means for receipt of saiD first detected and reference signals therefrom and effective to terminate the substitution of said second detected and reference signals, so as to revert to the feeding of said first detected and reference signals to said level detector means, when said vehicle exceeds the depth selected by said depth selector means by a predetermined amount; takedown means connected to said pressure responsive means and to said depth selector means for receipt of said first detected signal and said first reference signal therefrom and effectively connected to said level detector means via said mode selector means when it is in said second position and effective to substitute said first detected and reference signals for said second detected and reference signals when said vehicle is within a predetermined distance with respect to said upper boundary surface; rate responsive means connected to said pressure responsive means for receipt of said first detected signal therefrom and producing an output signal related to the time rate of change of said first detected signal; summing means connected to said level detector means for receipt of said control signals therefrom and connected to said rate responsive means for receipt of said rate signals therefrom and generating a composite signal related to the sum of said control and rate signals; and motor means electrically connected to said summing means for receipt of said composite signal therefrom and operative so as to be electrically driven thereby and connected mechanically to said attitude control means.

10. A countermeasure system for concealed explosive means which are attached to mooring lines so as to be moored within an aqueous medium having an upper and lower boundary surface, said system comprising: tractor vehicle means operating proximate to said upper boundary of said aqueous medium and providing propulsive force for said system; tow line means attached at its bitter end to said tractor vehicle means; depressor means attached to said tow line means at the distal end thereof for providing a dynamic force as a result of the propulsive force imparted thereto by said tractor vehicle via said towline means to effect the submergence within the aqueous medium of said distal end thereof; cutter line means attached to said tractor vehicle at the bitter end thereof and attached to said depressor means at an intermediate point therealong to extend beyond said depressor means; cutting means attached to said cutter line at intervals along said portion thereof extending beyond said depressor means; otter-depressor means attached to said cutter line at the distal end thereof and responsive to the propulsive force transmitted thereto by said cutter line to deploy said cutter line in a laterally protrusile relationship to the course of said tractor vehicle and submerged within said aqueous medium; and float vehicle means attached to said otter-depressor means for buoying said otter-depressor and the cutter line carried thereby to a controlled position within said aqueous medium predetermined as an optimum intercept point of said mooring lines, said float vehicle means comprising; a body portion; hydrodynamic lift producing means attached to said body portion for producing a dynamic force as said float is towed through said aqueous medium to oppose the depressing action of said otter-depressor means; attitude control means effectively attached to said body portion for changing the angular attitude thereof relative to the direction of towing movement thereof so as to effectively alter the angle between said lift producing means and the direction of relative flow of the aqueous medium; pressure responsive means responsive to the pressure of the aqueous medium at the float level to generate a signal related to the distance between said float and said upper boundary surface; sounding means generating a signal related to the distance between said float and said lower bouNdary surface; and control circuit means within said body portion and connecting said pressure responsive means and said sounding means to said attitude control means for selective operation thereof by a selected one of the signal outputs of said pressure responsive means or said sounding means. addition, the heat output per unit of combusted gas is very good.