US 3838642 A
A pop-up mine, anchored to the bottom and remaining under the surface of a body of water for destroying ASW and sonar dunking helicopters. The mine case includes an outer skin comprising fragment projectiles bonded to an explosive sheet. Deployed by a submarine, an anchor separates and sinks to the bottom, paying out cable to leave the mine close to the surface. A hydrophone, discriminating for detecting helicopters, activates a cable cutter and a rocket motor. The mine case pops to the surface, is lifted by the rocket to a predetermined altitude, and explodes to disperse the metal fragments, thus disabling the helicopter.
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Description (OCR text may contain errors)
0 United States Patent 11 1 1111 3 838 62 Shimberg Oct. 1, 1974 1 POP-UP ANTIHELO MINE 3,293,676 12/1966 Link 102/18 x v 3,513,750 5/1970 Penza 89/1.809  Invent Lee slver SPrmg 3,675,577 7/1972 Sternberg 102 67  Assignee: The United States of America as represented the Secretary of the Primary Examiner-Ben amin Bol'chelt Nay w i to Assistant Examiner-C. T. Jordan Art A r F RSS"JACk orne, en, 22 Filed: Nov. 15, 1972 g g c'asma 6  Appl. No.: 306,971
 ABSTRACT A pop-up mine, anchored to the bottom and remain-  US. Cl 102/10, 89/1.809, 191221136 ing under the Surface Ofa body of water for destroying 51 1m. (:1. F42b 22/18, F42b 22/26 g fim g j tl l Q if  Field 61 Search 102/7, 10, 13, 16, 14; b e er S P comprsmg ragme es onded to an exploswe sheet. Deployed by a subma- 89/1.809, 1.81, 114/20, 21
rme, an anchor separates and Sll'ikS to the bottom, t cable to leave the mine close to the sur-  References Cited paymg f.Ahdh,d tfdtthl- UNITED STATES PATENTS 1 16. 36325;": c$ilir ndL rififel iofol. 1,588,932 6 1926 Blair 114 21 A i' fii'ii gag ga s to the surface, is lifted by the rocket to a predetermined altitude, and explodes to 1c ieson 3,010,416 [1961 114/23 ggspterrse the metal fragments, thus dlsablmg the hel1 3,045,596 7/1962 244/311 p 3,093,033 6/1963 Draim et al 89/1.809 8 Claims, 4 Drawing Figures PATENIEUBCI H 3.838.642
sum HP 3 FIG.2
l? I Q4 68 I72 i 70 40 Q I k POW 66 ,./22 SUP POP-UP ANTIHELO MINE BACKGROUND OF THE INVENTION This invention relates generally to underwater weapons systems such as mines and torpedoes and more particularly to a pop-up mine that detects and destroys ASW helicopters hovering over the water having the intent to detect and destroy a submarine At present there is no known offensive weapon that may be effectively used by a submarine to attack an Anti-Submarine Warfare helicopter or airplane. The submarine may only defensively hide by running away or diving deep to avoid detection and subsequent attack. The use of the deck gun of the older submarines required that the submarine expose itself by surfacing to fire on the aircraft.
The instant invention provides an offensive weapon for a submarine to use effectively against ASW aircraft that is triggered by the attacking aircraft.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an effective sea-to-air offensive weapon.
Another object of the instant invention is to provide a submarine with an effective offensive weapon against ASW aircraft.
A further object of the instant invention is to provide a mine that is concealed under the sea surface which is released 'and lifted to an altitude to disable an aircraft.
A still further object of the present invention is to provide a mine that is activated by and will disable the attacking aircraft.
Briefly, these and other objects of the present invention are attained by a pop-up mine concealed below the waters surface that detects and destroys ASW helicopters hovering over the water with the intent to locate and destroy a submarine. The mine is deployed by a submarine, and subsequently releases a separable anchor which sinks to the bottom leaving the mine case concealed just below the surface of the water. A discriminating hydrophone, on the mine case, picks up the low frequency noise created by the downwash of a helicopter rotor when it is searching or dunking to listen for submarines. Upon hearing a helicopter, the hydrophone activates an anchor cable cutter and a rocket motor, causing the mine case to pop to the surface and be lifted to a predetermined altitude. The outer skin of the mine, composed of metal fragments bonded to an explosive sheet, is caused to explode, releasing flack projectiles which disable the helicopter.
BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention and the many attendant advantages thereof will be readily appreciated as the same becomes better understood by DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like refer- 5 ence numerals designate corresponding parts throughout the several views. there is shown generally in FIG. 1 a pop-up mine in an air-sea enviroment 12. A submarine 14 is shown as having just planted the mine system by expelling it out a garbage ejector or torpedo tube port 16 as shown in position A.
After planting as shown in position B the pop-up mine 10 separates, leaving a mine case 18 floating concealed under the surface, and a separable anchor 20 sinks to the bottom paying out a mooring line 22. In po- 5. sition C the mine is activated by cutting the mooring line 22 and energizing a rocket motor to pop to the surface (position D) and ascend to a height to disable a hovering and dunking ASW helicopter 24 (position E).
20 Referring now to FIG. 2, the mine case 18, anchor 20, and mooring line 22 are shown in detail. The mine case 18 comprises a pair of hemispheres 26 of thin spun aluminum or the like overlaid with a plurality of sheets 28 of Starrflak. Starrflak" is a Naval Ordnance Laboratory invention comprising a grid of one-fourth inch square metal fragments bonded to an explosive sheet. The Starrflak may be overlaid with cheesecloth laminated on with an epoxy resin or the like. The hemispheres are secured together along flanges 30 using suitable fasteners and sealed with a rubber gasket 32. A cable 34 from a battery and firing assembly 36 (to be discussed hereinafter) inside the case, exits through a stuffing gland 38 and is electrically connected to a detonator 40 on each hemisphere 26 and attached to the Starrflak" by an adhesive or the like. Further, the cable 34 is electrically connected to a rocket motor and mooring line cutter initiator squib assembly 42.
Alongside the mooring line cutter and inside the case is a rocket motor 44 affixed to a mounting plate 46 sealed to the bottom of the case. The mounting plate contains a plurality of ports 48 through which the motor propulsive exhaust exits. The ports are sealingly closed by a port plate 50 secured by shear screws 52.
On top of the mine case 18 are flush-mounted hydrostats 54 which act as arming switches and a hydrophone 56 for activating the mine. l-Iydrophone 56 is electrically connected via a cable 58 to preamp 60 located at the bottom of the mine case, along with other electronics circuitry.
Referring now to FIG. 3 the electronic circuit contained in the battery and firing assembly 36 is shown in detail. The hydrophone 56 is electrically connected to an electronic filter 62 which passes only the desired low frequency band produced by the downwash of a helicopter rotor. The filters output is fed via cable 58 to the signal preamplifier 60 which produces a usable output. This output is fed to an electronic switch 64 capable of initiating the rocket motor and mooring line cutter initiator squib 42. The signal preamp 60 derives its power from a battery 66 electrically connected thereto.
current to the hydrophone preamp'60, the electronic switch 64 and thence to the initiator 42, and a firing circuit comprising a charging resistor 68, and a firing cathe mooring depth of mine case 18.
'In operation, the pop-up antihelo mine '10 is planted (View A) by the very submarine 14 that the ASW hovering helicpoter 24 is attempting to locate, by deploy ing the mine out the garbage ejector 16. After ejection, the anchor 20 separates from the mine case 18, paying out mooring line 22, and sinks to the bottom (View B) keeping the case submerged. When the anchor sinks below a predetermined depth, the mooring line spool 78 pawls and the anchor continues to the bottom. Pawling occurs a distance from the bottom equal to the desired case mooring depth, and is controlled by hydrostats 82 or the like.
Electrical arming of the mine occurs after ejection from the submarine and during the anchoring phase,
tance. Referring to FIG. 3 arming occurs by water pressure actuating the hydrostatic switches 54 causing power from battery 66 to be applied to the hydrophone preamplifier 60, the arming circuit resistor 68 and capacitor 70 charging it and the electronic switch 64.
The pop-up mine system now waits in position (FIG. 1, View'B) for a'ASW hovering, dunking helicopter. When a helicopter 24 nears the location, the hydro phone 56 picks up the low-frequency sound and pressure waves created by the rotor downwash. The electrical output of the hydrophone 56 is fed through filter 62 which passes only low frequency signals, and cancels high frequency sound emitted from passing shipping, ambient noise, sonar and marine life. The low frequency signal is fed via the cable 58 to the hydrophone preamplified 60. If the output is of sufficient magnitude, the electronic switch 64, such as a relay or silicon ,controlled rectifier, will activate applying a current to the rocket motor and mooring line cutter squib 42.
When the squib fires, the mooring line 22 is severed by squib 42 and the rocket motor 44 ignited, blowing out the jet port plates 50, allowing the mine case 18 to pop to the surface of the water and be lifted by the rocket into the air to an altitude of feet to 150 feet depending on the rocket used. At the apogee, the inertia or velocity discriminator apogee switch 72 closes, dumping the charge in the firing capacitor 70 into the detonators 40, detonating the Starrflak and spraying the area with metal fragments to disable the ASW helicopter.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. lt is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
What is claimed as new and desired to be secured by Letters Patent of the United States is:
1. A pop-up, anti-helo mine system adapted to be moored below the waters surface and to be propelled into the air upon detection of an air'target comprising:
allowing the submarine to cruise to a safe standoff dis a mine case adapted to be moored below the water's surface;
an explosive attached to said mine case;
an anchor assembly releasably connected to said minecase;
a mooring line connecting said anchor assembly to said mine case;
means for paying out said mooring line from said anchor assembly;
an acoustic detection device provided in said mine case to detect. target signals above the waters surface;
propulsion means for propelling said mine case out of the water; and
control means responsive to said acoustic detection device to release said anchor assembly and to activate said propulsion means.
2, The pop-up, anti-helo mine system'of claim 1, V
wherein said propulsion means comprises a solid rocket motor for propelling said mine to a predetermined altitude above the waters surface; 3. The pop-up, anti-helo mine system of claim 2, wherein said acoustic detection device comprises:
a hydrophone capable of receiving sounds in water and converting them to electrical impulses;
an electrical filter connected to said hydrophone for passing only low frequencies produced by a helicopter; and i a preamplifier for amplifying the impulses to a magnitude capable of activating the mine.
. 4. The pop-up, anti-helo mine system of claim 3 wherein said control means comprisesa rocket motor and cable cutter initiator squib electrically connected to said acoustic detection device for releasing said mooring line and igniting said rocket motor when said hydrophone detects a helicopter.
5. The popup, anti-helo mine system of claim 4 wherein said explosive comprises:
a metal sheet segmented to produce a plurality of metal fragments; and
an explosive sheet bonded to said metal sheet,
whereby the resulting laminant forms the outer shell of said mine case.
6. The pop-up, anti-helo mine system of claim 4 further comprising:
a firing circuit including a chargeable capacitor and resistor;
at least one electro-responsive detonator in contact with said explosive; and
an apogee switch for coupling said firing circuit to said electro-responsive detonator to initiate said detonator and consequently said explosive.
7. The pop-up, anti-helo mine system of claim 6 further comprising a plurality of hydrostatically operated arming switches for connecting a source of electrical power to said acoustic detection device, said initiator squib, and said firing circuit after deploying and anchoring.
8. The pop-up, anti-helo mine system of claim 7 wherein said means for paying out mooring line comprises:
a spool for winding said anchor line; and
a pawling mechanism coacting with said spool for releasing and stopping said spool.