US2914887A - Toy submarine - Google Patents

Description

Dec. 1,r 1959 l.. w. FLEISCHMANN TOY SUBMARINE Filed June 24, 1958 om 5.09 w... wm N Q Nm; m@

INVENTOR Lewis W. Fleischmann BY Sa/am ana/ Sia/ifa ATTORNEYS United States Patent TOY SUBMARINE Lewis W. Fleischmann, Baltimore, Md., assignor of fifteen percent to Nelson H. Shapiro and live percent to Harvey A. Jacobs and Charles Jay Pilzer, jointly, all ofWashington, D.C.

Application June 24, 1958, Serial No. 744,216

16 Claims. (Cl. 46-243) This invention relates to a toy submarine and more particularly to an electrically propelled toy submarine which is capable of submerging and surfacing automatically and yet which is so constructed that it cannot be lost by sinking entirely below the surface and failing to re-surface.

From its inception in the days of Leonardo da Vinci the submarine has been an object of fascination for child and adult alike. In more recent years interest in submarines has been spurred by their wide military usage. Hence, many attempts have been made to construct a toy submarine which will closely simulate the actions of its full-size counterpart.

In the early stages of toy submarine development, the vessels were propelled by spring motors, and more recently electric moto-rs of compact and inexpensive construction have been used. However, the problem of producing a toy submarine is not propulsion per se, but rather the means for causing the submarine to submerge and re-surface. In this respect the prior attempts to produce an operational and practical toy submarine have not been successful. Various schemes have been proposed, including adjusting the bow planes so that the submarine will dive when the motor is running (due to the force of the water on the moving planes) and` will surface when the motor stops; providing a gas generator or source which will force water from a submerged submarine and make it suiciently buoyant to surface; changing the center of gravity of the submarine by a motor-driven weight;`

permitting the submarine to strike the bottom so as to release a weight and increase the buoyancy of the submarine; and many others. All of these schemes are impractical for one or more reasons. Moreover, few, if any of them, ensure that the submarine will not be lost by sinking below the surface and failing to re-surface. The latter consideration is an important one, because toy submarines are usually used by children, who can ill afford their replacement.

In accordance with one prior art scheme of which the applicant is now cognizant, it was proposed to provide an electrically-driven submarine having a valve controlled by a iioat within the hull for admitting Water to the lower part of the hull, and a pump for expelling water from the hull upon the closing of the valve and the ener-l gization of the motor. As proposed, however, this scheme was not only impractical but was inoperative, and so far as the applicant is aware no such operative submarine was everproposed or produced. y

With the foregoing in view, it is accordingly a principal object of the present invention to provide a unique and improved toy submarine which is simple, practical, economical to build, substantially fool-proof, and which overcomes the deiiencies of the prior art.

Another important object of the invention is to provide a toy submarine which is capable of being propelled entirely on the surface of a body of water, or submerging and re-surfacing automatically, or submerging and remaining submerged, as it is propelled through the water.

Still another object of the invention is to provide a toy ice submarine which will closely and automatically simulate the submerging of a full-size submarine as it moves forward, and then the 1re-surfacing as the forward movement is continued.

Another important object of the invention is to provide a toy submarine which will submerge to periscope depth but which will not sink entirely from view.

A further object of the invention is to provide a novel toy submarine driven by an electric motor which also drives a pump-arranged to empty a ballast tank having a limited capacity for water which enters through a iloatcontrolled valve.

An additional object of the invention is to provide a toy submarine having a float-controlled valve which may be positively placed in closed or open position and which may be held open notwithstanding the immersion of the oat in water.

A still further object of the invention is to provide a toy submarine of the foregoing type which cannot sink even if the valve sticks open and even if the pump stops working.

Still another object of the invention is to provide a toy submarine of the foregoing type having a ballast tank so located as to have little deleterious effect upon the stability of the craft.

An additional object of the invention is to provide a toy submarine of the foregoing type with an extremely simple drive train for the propeller and the pump.

A still further object of the invention is to provide a submarine of the foregoing type in which batteries employed for energizing the electric motor are used as counter-balancing weights.

An additional object of the invention is to provide a toy submarine of the foregoing type in which Weights which are added to determine the buoyancy ofthe submarine are formed to provide a shelter for the ballast tank valve opening.

A still further object of the invetnion is to provide a toy submarine of the foregong type in which the float mechanism is housed within the conning tower so as to be shielded from view and yet readily accessible for operative manipulation.

Still another object of the invention is to provide a toy submarine of the foregoing type in which a simulated periscope is employed as an air passage for the ballast tank.

An additional object of the invention is to provide a toy submarine of the foregoing type having a centrifugal pump of highly efficient construction, which operates to pump water even with little centrifuging action, and which requires no priming.

Still another object of the invention is to provide a toy submarine of the foregoing type which can be constructed almost entirely of plastic or sheet metal material and thus is readily adaptable to mass production.

The foregoing and other objects, features, and advantages of the invention will become more readily apparent and more fully understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings, which illusstrate a preferred embodiment of the invention, and wherein:

Figure l is a side elevation View of the toy submarine of the invention partially broken away to show the interior;

Figure 2 is a perspective View of a detail of the toy submarine;

Figure 3 is an exploded perspective view of the pump of the invention;

Figure 3A is a vertical sectional view of the assembled pump; and

Figures 4A, 4B, and 4C are explanatory diagrams illustrating three alternative methods of operation of the toy submarine of the invention.

Referring to the drawings, and in particular to Figure l thereof, the submarine of the invention comprises a hollow hull 10 which may be molded from a high impact plastic, the halves of the hull divided along a longitudinal vertical plane being separately molded and then joined to form the complete hull. The hull may also be formed from sheet metal, as by shaping the lower portion of the hull and joining it to the deck portion. The hull is provided with bow planes 12, Which may be formed integrally with the sides of the hull, and with a superstructure including a conning tower 14, a periscope 16, and a deck gun 18. At the rear of the hull is located a rudder 20 suspended from a vertical pivot rod 22. Forward of the rudder is a propeller 24 mounted on the end of a drive shaft 26 which passes into the interior of the hull through a bearing sleeve 28, which may be formed integrally with a depending supporting iin 30.

Located within the central region of the hull is a ballast tank 32 having a front wall 34 and a rear wall 36 spaced from the respective front and rear extremities of the hull so as to form front and rear compartments within the hull. The ballast tank is located beneath the conning tower 14 and the periscope 16, and the periscope is hollow so as to provide an elongated air passage for communication between the interior of the ballast tank and the atmosphere at the top of the periscope. The ballast tank is sealed from the front and rear compartments of the hull by the walls 34 and 36 and is closed at its top by the deck which forms the upper surface of the hull.

At the bottom of the ballast tank is located a valve generally designated 38 and having a valve seat or opening 40 and a movable valve body 42. The val-ve seat may be formed integrally with the hull and the valve body may comprise a conical plug of hard rubber or plastic which is self-centering within the tapered valve opening. Alternatively, a simple poppet valve could be employed.

At the bottom of the hull beneath the ballast tank is a weight 44, which may be lead, which ensures that the center of gravity of the submarine is located substantially at the ballast tank and which ensures the proper buoyancy of the submarine as will be described more fully hereinafter. The weight 44 shields the valve and provides a shelter 46 for the valve opening. This shelter may be closed to deb-ris, but still permit the passage of water, by the provision of a section of screen 48 fixed to the weight, as by molding it thereto. The weight may also be shaped to form a level support for the submarine when it is not in use.

The valve body 42 is attached to an operating rod 50 which extends downwardly from the conning tower through the ballast tank. The valve rod may be formed from stiff piano wire, for example, and is suiciently rigid to exert a force on the valve body 42 in both axial directions. The rod passes through a small bushing 52 in the deck of the submarine to a float 54 housed within the conning tower. The oat may be formed of a plastic foam material, for example, and is supported on a yoke 56 pivotally connected to vertical posts 58 mounted on the deck as more fully shown in Figure 2. The float may thus move up and down in the conning tower.

The upper end of valve rod 50 is pivotally attached to an arm 60 pivotally attached to the float yoke, and motion of the oat in a vertical plane is transmitted by the valve rod t) to the valve body 42. As shown in Figure 2, a spring 62 which is placed in tension when installed is connected at one end between the junctions of the posts 58 and the deck and at the other end between the upper extremities of the legs of the yoke 56. In moving between its lower and upper positions, the float causes the legs of the yoke to move from one side of the vertical plane through the posts 58 to the other, and the spring 62 snaps from one side of this plane to the other along with the yoke legs, so that the float mounting forms an over-center or toggle mechanism capable of maintaining the oat in its up or down position in the absence of a sut`n`cient opposing force on the float.

The oat 54 may be latched in its down position by a simple latch, which, in the form shown, comprises a U- shaped ring 64 with the ends of its legs pivotally attached to a projection on the deck and with its bight arranged to receive a notched projection 66 attached to the lloat and passing through a slot 68 in the conning tower as shown in Figure 2.

In order to permit water to reach the float, if the conning tower is substantially closed as shown, openings 70 are provided in the bottom of the conning tower for the passage of water. The slot 68 may serve to permit the expulsion and admission of air with respect to the conning tower. Where esthetic considerations are not so important, the top and rear of the conning tower may be left substantially open and slots 70 omitted.

In order to provide for the expulsion of water from the ballast tank 32, a pump 72 s mounted in the rear compartment behind the ballast tank. In the form shown the pump is a centrifugal type that is self-priming even at high speeds and as can be seen more fully in Figure 3 has a generally cylindrical housing 74 (except for an involute bulge at one side) which may be formed integrally with one end closure and provided with a cover 78 for closing the other end of the housing after the rotor 76 has been inserted. The rotor has a circular disc 80 fitting the circular periphery of the housing with working clearance, a central shaft 82, and a plurality of blades 84 normal to a surface of the disc and preferably formed integrally with the shaft and the disc. The blades 84 extend inward from the disc periphery and have a length about 1/2 of the disc radius. Each blade is inclined at about 15 to a radius passing through the central blade portion with the inner end of the blade leading. Four openings 85 pass through the disc between successive pairs of blades. One end of the shaft 82 passes through a central opening 86 in one end of the housing 74, and the other end of the shaft is received within a cylindrical bearing cup 88 for-med in the other end of the housing. Suitable washers 90 are provided around the ends of the shaft, and the shaft end which passes through opening 86 is provided with a suitable packing or at least closely tted to the opening so as to reduce leakage to a minimum. If there is any slight leakage from the pump into the rear compartment of the hull, the water accumulated may be drained from the hull by opening a suitable drain plug or cork indicated generally at 91.

The inlet to the pump housing is located near the axis of the rotor and below the shaft 82, as shown at 92, and the outlet of the pump housing is located in the circumferential wall and at the top of the housing, as shown at 94. As shown in Figure l, the inlet is connected by an inlet pipe 96 to the central portion of the bottom of the ballast tank 32, passing snugly through the rear wall of the ballast tank. The outlet 94 is connected by an outlet pipe 98 which terminates in an opening to the exterior of the hull preferably at or near the deck level.

The pump 72 is driven by an electric motor 100 mounted in the hull behind the pump and has its drive shaft coupled to the pump shaft as by a short length of spring 102 which may be soldered to the shafts. This motor s preferably of the compact inexpensive type now being widely employed as a source of toy boat propulsion. The other end of the motor shaft is coupled, as by a similar length of spring 104, to the end ofthe propeller drive shaft 26 which protrudes from the inner end of sleeve 28. In this manner the motor is located close to the pump and to the propeller and is able to drive both of these elements directly without the interposition of gear trains or the like.

The motor 100 is energized from a 3-volt source of supply constituted by two 11/2 volt flashlight batteries gigas? 106, which arerflo'c'ated in the forward compartment of the hull in' front' ofthe ballast tank 32. rlhese batteries are connected Vin series betweenA a pair ofy contacts 108 and `110;` If` the hull is formed of` metal, contact 108 may bel electrically connected, as by soldering, directly to the hull, while the contact 110 is .insulatedtherefromt With such an arrangement, the hulll itself may con`- stitute the return circuit for the battery, and no wires need be connected to terminal 108. If the hull is formed of plastic, separate insulated wires are connected to terminals 108 and110.` In the formshown it is assumed that a hull return circuit i-s used, .anda single wire 112 is shownpassing from'terminal 110` to one terminal of a switch 113 mounted on the deck. The other terminal of the switch vis connected bya wire 114 to one terminal of the motor 100, the other terminal of which is connected to the hull as indicated `at 116. If the wires pass through the ballast tank, suitable seals are of course provided to prevent leakage of water. A1- though a simple knife switch is shown,.a toggle switch or any other suitable type switch may be employed. Suitable precautions must be taken, of course, to prevent leakage of water around the switch into the hull.

In order to permit access to the battery compartment, a hatch is provided at 118, and in the form shown the hatch cover supports the deck gun 18. Any suitable method of providing a waterproof hatch closure may be used, and in the form indicated in Figure l, the deck gun constitutes a handle connected to a vertical shaft 120 which passes through the hatch cover to a flat link 122 pivotable through 90 degrees in a horizontal plane so as to ride up onto cam inclines 124 lsecured underneath the deck on opposite sides of the hatch opening, and thereby draw the hatch cover tightly down onto the hatch opening.

With the batteries 106 in the forward compartment as shown, counter-balancing of the weight of the motor and pump is obtained. A good balance may be ensured lby properly distributing the weights 44 at the bottom of the hulland by placing weights elsewhere if necessary. In this manner both the center of gravity and the center of moments are located substantially at the ballast tank, and the stability thus obtained is not upset by water entering or leaving the tank.

In accordance with an important feature of the invention, the capacity of the ballast tank is so chosen that withl the tank completely lled, the submarine will not submerge below the level of the top of the periscope. To ensure this result it is necessary to determine the initial buoyancy of the submarine as a whole including the float, and then to choose a tank size of sufficient capacityto permit the submarine to sink to periscope depth when the tank is full, but no farther. Thus even if the valve 38 should stick open through some unforseen fault in opertion or if the pump should stall because of debris tangled in the propeller 24, the submarine will still be sufciently visible to ascertain its location. Moreover, any slight leakage which occurs around the opening in the deck for valve rod S0 will be unimportant. This :feature completely eliminates the loss of the toy submarine by its sinking and failing to` re-surface. Such loss is common with prior toy submarines when they are operated in large or deep ponds.

The toyV submarine of the invention may be set to execute at least three different maneuvers which closely simulate the corresponding actions ofa real submarine. Assume with reference to Figure 4a that the submarine S is placed on the surface of a body of water W at one shore A and pointed toward the opposite shore B. Assume further that the float 54` is in its down position as shown in Figure l, and the latch 64, 66, is released. When the switch 112 is closed the motor 100 will be energized, causing the propeller 24 to turn and causing vthe submarine to move in the direction of-*thev opposite shore B. Water will enter the valve opening 40 at the .flow into the pump 72 through the inlet pipe 96, the

air in the pump'housing being expelled. upwardly through the, outlet pipe 98;k Eventually the pump housing; will be filled with water, and the pump, driven by the same motor 100 which drivespropeller 24will operate ati maximum eiciency, causing water to be expelled through the outlet pipe 98 to the exterior of the hull. t By'f virtue of its construction the pump needs no priming; andlicommences to pump automatically.

In accordance with another important, feature` ofthe inventionthe rate at which the. pump. 72can'- withdraw w-ater from the ballast tank 32 is made less` than the vrate at which water can enter the tank when the valve-38 is open. This; relationship is` obtained by predetermining the size-,ofthe valve opening v40the air passage 1,6,l and the pump inlet and outlet pipes 96 and 98, taking@A into consideration the capacity of the:V pump when driven at its normal speed by the motor 100. Thuswith'` the valve:` inthe ballast` tank open water. will continue-.to

-accumulate'in'the tank notwithstanding. the operation of the pump, and the submarine willi continuetosubmerge as it movestoward the opposite shore B.

Finally, vthe water` will reach the conning tower and enter the `openings 70, the air in the conning, towerbeing expelled through the` slot 68. Whenthe water level reaches the, float 54, the lioat. will be immersed inthe water` and lwill rise dueto its4 inherent buoyancy,.tens ing spring 62, which has insuicient restraining forcey `to prevent the float from rising. The upward4 movement of the floatcause's pivotal movement of the yoke56 on posts 58, and when the. legsI of the,` yoke pass their vertical position, the tension of spring 62 adds' to the buoyant force on the floatand snaps the lioat to itsy up position, closiugfvalve 38. When this occurs, the sub.- marine is submerged with just the. top portion of the conning tower exposed.

Thepump 72 continues to withdraw water from the v ballast tank, but since the water may no longer enterA the ballast tank through the valve opening, the pumping rate is suflicient to expelsubstantially all of thev water from the tank. During this: process, air isy admitted to thetank through the periscopey air passage, the buoyancy of the submarine is increased, and the submarine surfaces. Thus, the trip to the distantshore will be completed on the surface, thevalve 38 remaining closed under the action of the over-center float mounting. A return trip may be made by simply turning the submarine around and manually setting the float to its down position.

As indicated. in Figure 4b, the submarinemay also be operatedas, a surface vessel. For such operation of the submarine it is simply necessary to ip theoat to its up position` before placing the submarine in the water. The valve 38 will then remain closed throughoutthe trip, and no water will enter the ballast tank.

As indicated in Figure 4c, the submarine canbeoperated submerged for the entire trip oncev it has submerged asv set forth with respect to Figure 4a. To accomplish tbi'sthe oat is latchedin its down position by theY latch mechanism 64, 66, so that the valve 38 will remain open. The ballast tank will then ill and will remain substan. tially full throughout the voyage, because the pump 72 is unable to pump out the ballast tank with the valve open, as setj forth previously. With water in the ballast tank throughout the trip, the submarine'willremainsubf merged.

From the foregoing it will be apparent to those skilled in the art thatl a unique and improved toy submarine is provided bythe present invention. It will be further apparent that while a preferred embodiment of the invention has been shown and described, changes can be made without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims. For example, if it were desired that the submarine submerge to a greater extent before the oat is operated, the water inlet holes 70 in the conning tower could be raised above the float in its down position, but this would necessitate removing the accumulated water in the conning tower before the oat could be set in its down position again. Accordingly, the foregoing embodiment is to be considered illustrative, rather than restrictive of the invention, and those modifications which come within the meaning and range of equivalency of the claims are to be included therein.

I claim: v

1. A toy submarine comprising an elongated at least partially hollow hull, a ballast tank within said hull having a water inlet opening adjacent its bottom and an air passage adjacent its top communicating with the atmosphere, a float mounted on top said hull for upward and downward movement and having means for holding it up or down in the absence of a suicient external opposing force, a valve operator connected to said float and passing downwardly through said hull to said water inlet opening, a valve body attached to said operator and arranged to open and close said opening in response to downward and upward movement of said oat, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said oat being exposed to the water surrounding said hull when the submarine is submerged to the level of the lloat, and the buoyancy of said hull being correlated with the capacity of said-tank such that said tank will receive sufiicent water to cause the submarine to submerge to a level at which ksaid float is moved upwardly by the water surrounding said hull.

2. The submarine of claim 1, said oat having manually accessible operating means for moving it upward or downward.

3. A toy submarine comprising an elongated at least partially hollow hull, a ballast tank within said hull having a water inlet opening adjacent its bottom and an air passage adjacent its top communicating with the atmosphere, a float mounted on top said hull for upward and downward movement, the buoyancy of said hull and said oat-being correlated with the total capacity of said tank such that said submarine will not entirely sink below the surface of the surrounding water even when said tank is full of water, a valve operator connected to said float and passing downwardly through said hull to said water inlet opening, a valve body attached to said operator and arranged to open and close said opening in response yto downward and upward movement of said float, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said float being exposed to the water surrounding said hull when the submarine is submerged to the level of the float, and the buoyancy of said hull being correlated with the capacity of said tank such that said tank will receive suicient water to cause the submarine to submerge to a level at which said float is moved upwardly by the water surrounding said hull.

4. The submarine of claim 3, further comprising manually accessible releasable latch means to hold said oat in its downward position notwithstanding its immersion in water.

5. A toy submarine comprising an elongated at least partially hollow hull, a ballast tank within said hull having a water inlet opening adjacent its bottom and an air passage adjacent its top communicating with the atmosphere, a oat mounted on top said hull for upward and downward movement, said oat having an over-center pivotal mounting arranged to hold said oat up or down, a valve operator connected to said oat and passing downwardly through said hull to said water inlet opening, a valve body attached to said operator and arranged to vopen and close said opening in response to downward and upward movement of said oat, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said oat being exposed to the water surrounding said hull when the submarine is submerged to the level of the float, and the buoyancy of said hull being correlated with the capacity of said tank such that said tank will receive suicient water to cause the submarine to submerge to a level at which said oat is moved upwardly by the water surrounding said hull.

6. A toy submarine comprising an elongated at least partially hollow hull, a ballast tank within said hull having a water inlet opening adjacent its bottom and an air passage adjacent its top communicating with the atmosphere, a float mounted on top said hull for upward and downward movement, a valve operator connected to said oat and passing downwardly through said hull to said water inlet opening, a valve body attached to said operator and arranged to open and close said opening in response to downward and upward movement of said oat, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said pump having a pumping rate less than the rate at which water can enter said water inlet opening, said float being exposed to the water surrounding said hull when the submarine is submerged to the level of the iloat, and the buoyancy of said hull being correlated with the capacity of said tank such that said tank will receive sufficient water to cause the submarine to submerge to a level at which said oat is moved upwardly by the water surrounding said hull.

7. lA toy submarine comprising an elongated at least partially hollow hull, a ballast tank within said hull having a water inlet opening adjacent its bottom and an air passage adjacent its top communicating with the atmosphere, a float mounted on top said hull for upward and downward movement, a valve operator connected -to said float and passing downwardly through said hull to said water inlet opening, a valve body attached to said operator and arranged to open and close said opening in response to downward and upward movement of said oat, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said pump being the centrifugal type having a housing and a rotor rotatable about a horizontal axis, said pump having its outlet at the top of the housing and having its inlet near 4the bottom of said tank, whereby said pump is self-priming, said oat being exposed to the water surrounding said hull when the submarine is submerged to the level of the oat, and the buoyancy of said hull being correlated with the capacity of siad tank such that said tank will receive suicient water to cause the submarine to submerge to a level at which said float is moved upwardly by the water surrounding said hull.

8. The submarine of claim 7, said pump being of the type having a circular housing and a rotor with radial backwardly curved blades.

9. A toy submarine comprising an elongated at least partially hollow hull, a ballast tank within said hull having a water inlet opening adjacent its bottom and an air passage adjacent its top communicating with the atmosphere, said tank being located in the central region of said hull and being spaced from the front and rear extremities of the hull, a float mounted on top said hull for upward and downward movement, a valve operator connected to said float and passing downwardly through said hull to said water inlet opening, a valve body attached to said operator and arranged to open and Close said opening in response to downward and upward movement of said oat, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said float being exposed to the water surrounding said hull when the submarine is submerged to the level of the oat, and the buoyancy of said hull being correiated with the capacity of said tank such that said tank will receive sufficient water to cause the submarine to submerge to a level at which said float is moved upwardly by the Water surrounding said hull.

l0. The submarine of claim 9, said tank extending to the top of said hull, and said valve operator comprising a rod extending through said tank.

l1. The submarine of claim 9, said tank being located subs'tantially at the center of gravity and center of moments of said submarine.

l2. The submarine of claim 9, said pump being driven by an electric motor, said motor and pump being connected in tandem behind said tank, said submarine also having a propeller driven by said motor, said motor being energized by batteries located in front of said tank to counterbalance said motor and pump.

13. The submarine of claim 9, said hull having a weight attached thereto below said tank and formed to provide a shelter for said valve opening.

14. The submarine of claim 9, further comprising a simulated conning tower mounted on said hull above said tank, said float being housed within said conning tower, and said conning tower being formed to permit water to reach said oat.

15. The submarine of claim 9, said submarine having a simulated periscope forming said air passage.

16. A toy submrine comprising an elongated hollow hull, a ballast tank located within the central region of said hull and having front and rear walls spaced from the front and rear extremities of the hull, respectively, said tank having a water inlet opening at its bottom and an air passage at its top communicating with the atmosphere, lloat mounted on said hull above said tank for pivotal movement about a horizontal axis, said float having a manually operable over-center pivotal mounting arranged to hold said iloat up or down, a valve rod connected to said oat and passing downwardly through said tank to said water inlet opening, a valve body attached to said rod and arranged to open and close said opening in response to downward and upward movement of said float, respectively, a pump in said hull having an inlet in said tank and an outlet at the exterior of said hull, said pump having a pumping rate less than the rate at which water can enter said water inlet opening, said oat being exposed to the water surrounding said hull when the submarine is submerged to the level of the float, the buoyancy of said hull being correlated with the capacity of said tank such that said tank will receive sufiicient Water to cause the submarine to submerge to a level at which said float is moved upwardly by the water surrounding said hull, and means including a motor for driving said pump and propelling said submarine.

References Cited in the le of this patent UNITED STATES PATENTS 2,089,888 Garrett Aug. l0, 1937 FOREIGN PATENTS 330,268 France July 26, 1938

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