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A torpedo is self propelled under water missiles with its own guidance system. They are also used as parts of other weapons. It is designed to detonate on contact or in proximity to a target. The torpedoes used against submarines are shorter and lighter .The main types of torpedoes used in U.S navy are MARK 46, MARK 48, and MARK 50.
In my topic, I would like to give a brief description on torpedoes, its working and its features .also I would like to explain the launching tube.
Torpedoes.doc (Size: 2.09 MB / Downloads: 187)
A torpedo is a self propelled underwater missile with its own guidance system. They are also used as parts of other weapons.It are designed to detonate on contact or in proximity to a target. In some cases it is provide with homing equipment enabling it to seek out its target.
I t is fitted with a detonator which detonates the explosive change in the warhead when it strikes the target or comes close to it.Torpedos may be launched from submarines surface ships helicopters or fixed wing aircrafts. The torpedoes used against submarines are shorter and lighter.
MAIN SECTION OF A TORPEDO
The typical torpedo comprises of a warhead, the air flask section (or battery compartment in an electrically powered torpedo), the after body (comprises the engine room and compartment containing the regulating equipments) and the tail. The war head carries the exploder mechanism and contains explosive charge. The air flask section of a torpedo contains compressed air, water and fuel The after body contains the gyroscope, the depth regulating mechanism, the combustion chamber (in which the fuel is burned and water turned into steam) and turbine or reciprocating engine (powered by the air and steam mixture which drives the propeller mounted on the coaxial shafts rotating in opposite directions).The tail section also contains the tail blades and the rudders.
Surface ships may launch torpedoes from tubes which can be aimed in desired directions. The torpedo may be launched sideways from a special launching frame, a method used on small crafts. Submarines and also some surface ships are provided with launching tubes built into the hull. Above water torpedo tubes are fired by a charge of black powder or by compressed air. The compressed air is always used in underwater tubes alternatively a submerged tube is sometimes of the type that can be flooded so that the torpedo emerges under its own power. Torpedoes may also be launched from aircrafts flying at relatively low altitude.
A fairly recent development is the rocket propelled torpedo used for against submarines. this may take the form of an ASROC(Anti Submarine Rocket)for use from surface ships or a SUBROC(Submarine Rocket) fired from the torpedo tube of a submarine. it emerges from water, travels some distance through the atmosphere and then reenters the water on approaching its submerged target. With these devices the torpedo is automatically switched on when the torpedo enters or re-enters the water. This mechanism is preset before launching, i.e., it is fed the data of enemy’s position (distance, course, speed) before launching.
Functional Description of Torpedoes
Torpedoes are driven by multi cylinder reciprocating engines, turbines or battery powered electric motors. The propulsive agent may be compressed air; a mixture of compressed air and steam, electricity etc.Fuels may be oil, alcohol, hydrogen peroxide etc.
With compressed air and steam, air is supplied from a flask through a pressure reducing valve which is present tenable the torpedoes to develop the appropriate speed .Oil atomized by the compressed air is burned in the combustion chamber into which water is sprayed so that steam is generated. The resulting mixture of air and steam is fed to four cylinder radial type engine .after the expansion the exhaust gas is expelled, leaving wake of bubbles.
Death control is affected by hydrostatic pressure and is preset to give a depth at which the torpedoes will be most effective against its target .Lateral guidance is controlled by a gyroscope by which the torpedoes can be made to travel in a predetermined linear course or a curved path.
The conventional torpedo is fired in a straight line. An increased chance of scoring a hit is obtained by firing two or more torpedoes simultaneously in a fanwise pattern .Another method is to program the torpedo to follow a zigzag or spiral path, so that it will repeatedly cross the targets path. Another method of increasing the accuracy is provided by the wire guided torpedo which is connected to the attacking vessel by an electric wire through which control signals are fed to keep the torpedo on a collision course with the target despite the evasive action of the later .further advance in the direction is the homing torpedo which is provided with a spiral device mounted in the nose which may consist of a sensitive acoustic receiver that picks up the sounds emitted by the enemy vessel and control torpedo steering accordingly. Alternatively the device itself may generate a sound signal and home on the echo reflected from the target(active acoustic torpedo).Modern antisubmarine torpedoes are almost of the homing kind .
Exploder mechanisms are of various kinds. Detonation may be caused by physical impact with the target by acoustic influence(noise of enemy vessels engine or propellers),by magnetic influence (change o f magnetic field in the vicinity of the target ),by optical influence (the shadow of the enemy vessels when torpedo pass under it).After launching a torpedo must travel some distance before it become s armed .It must be fitted with a device that will automatically sin it when it completes its run without having hit the target. These precautions are necessary to reduce risk to the attackers own ship.
A submarine tube resembles a large naval gun. It has a barrel with breech and muzzle. As the gun fires a shell, the submerged torpedo tube fires a torpedo using compressed air rather than the explosive for the purpose. One marked difference between the torpedo tube and the gun however is that the torpedo tube’s title (torpedo) is self propelling, the tube supplies only the initial impulse for its start.
At each end of the torpedo tube or barrel is a door, the breech door at the loading or operating end inside the submarine, the muzzle door at the out board and the firing or ejecting end opening out into the water. These doors are operated respectively by the breech operating mechanism and the muzzle door operating mechanism both of which are located at the both ends of the tube inside the submarine .with the muzzle door close, the breech door is opened and the torpedo is loaded into the tube. In order to drain off all the water that has entered the tube during the firing, there is a system of drains and valves, all operated from the breech end.
The firing mechanism which sends the torpedo out of the barrel and into the target includes an impulse tank charged from the submarines high pressure air system, also a system of ejecting valves, gauges etc.
WORKING OF THE TORPEDO TUBE
Shown on these pages is a diagramatic explanation of how a submarine torpedo tube works. The process is greatly simplified here, and only basically resembles the actual operation. It is possible that a simple torpedo tube might be constructed along these lines that would actually fire a torpedo. All that is intended in these diagrams and the accompanying description is to reduce the theory of the torpedo tube to its barest fundamentals. With these fully grasped, the refinements which cause the modern torpedo tube to function as it does will be more easily understood. In the simplest form possible, a torpedo tube would need to consist of no more than a barrel to receive the torpedo, and the means of providing the force necessary to discharge the torpedo from the barrel. In this ease, the force is supplied by a tank of compressed air which may be released into the barrel by opening a valve. The breech of the barrel is fitted with a door which serves the dual purpose of providing an opening into the tube, and blocking the escape of the compressed air from the barrel by any other means than forcing the torpedo ahead of it and out of the muzzle. Since the muzzle is submerged in sea water, it must also be fitted with a door to shut
out the sea while the breech door is opened to allow the torpedo to be loaded into the tube. In this respect, the tube with its interlocked doors acts as an air-lock (like an escape hatch). A cardinal principle of submarine torpedo tube construction is that one or the other of the tube's two doors must always be closed, to prevent the entrance of the sea into the submarine's interior. As will be shown in following pages of this pamphlet, interlocking devices are fitted to submarine tubes to prevent the simultaneous opening of both breech and muzzle doors. It scarcely seems necessary to
point out the suicidal folly of any attempt to defeat the purpose of these interlocking devices. With the muzzle door closed to prevent entrance of the sea into the tube, its breech door is opened and a torpedo loaded into it. The breech door is then closed and the muzzle door may be opened. It must be remembered, however, that at any
considerable depth below the sea's surface, there will be water pressure against the muzzle door which may be too great to be overcome by whatever force is applied toward opening it. To offset this external pressure on the muzzle door, an equal pressure is built up within the tube by admitting water from a tank (simultaneously venting the displaced air into the ship) and then
opening a valve which communicates with the sea. With this done, no more force is required to open the muzzle door than would be needed if the tube and door were not submerged at all. With the torpedo tube flooded with sea water at the same pressure as that outside the muzzle door, the door is opened and the tube is ready to fire the torpedo. In actual practice, the tube is flooded from tanks within the submarine rather than from the sea itself; this avoids disturbing the trim or balance of the vessel through increasing the weight of water it carries.
The tube now being ready to fire, a valve between the compressed air supply and the tube is opened. It is obvious that the air pressure must exceed the sea pressure by sufficient margin to force the torpedo out of the tube. Here again, in actual practice, the air charge is not permitted to completely fill the tube and escape into the sea, but is vented off so as to avoid causing a bubble of air to rise to the surface and thereby betraying the submarine's location. The torpedo having left the tube, the compressed air is shut off, and the tube fills with sea water. This tends to offset the lost weight of the torpedo, keeping the submarine in trim. In effect, this follows actual practice. A submarine is held submerged on level keel at any given depth by taking on or discharging carefully calculated amounts of water ballast. Failure to compensate for the weight of a heavy torpedo can badly upset the vessel's equilibrium.
The torpedo tube having filled with water, the muzzle door is closed, shutting out the sea. It is now possible to open a valve leading to a drain tank, and empty the tube, at the same time blowing in air
to replace the water, and to force it out faster. Thus the weight of the water taken aboard to offset the lost weight of the fired torpedo is retained in approximately the same locality. The breech door may, after all the water is drained out of the tube, be opened for reloading
TORPEDO DATA COMPUTER
The TDC aboard is a true mechanical computer. The TDC was unique in WORLD WAR 2. It was the computational part of the first submerged integrated fire control system that could track a target and continuously aim torpedoes by setting their gyro angles. The TDC mark III gave the US fleet submarine the ability to fire torpedoes without first estimating a future firing position, changing the ships course, or steering to that position, instead of hoping that nothing in the set up changed, a fleet submarine with the TDC could fire at the target when the captain judged the probability of making hits to be optimal.
In the WORLD WAR II, a torpedo’s gyro angle was set mechanically while it was in the tube. A shaft known as the spindle, slipped into a socket near the housing of the torpedoes course gyroscope. When the fire control system rotated the shaft, the gyroscope rotated. After being fired the torpedoes traveled on a straight path for a known distance called Reach. A delay in the release of the torpedo’s gyro steering mechanism by a threaded shaft determined the magnitude of the reach. Once engaged the steering mechanism brought the torpedo to anew course based on the angular offset of the gyroscope.
The mark III computer consisted of two sections, the position keeper and the angle solver. the position keeper tracked the target and predicted its current position. To do this the position keeper automatically received input of the ships speed from the pit log. The position keeper had hand cranks on its face that set the target length, estimated speed and angle on the bow. It also contained a sound bearing converter that calculated the targets location based on sonar measurements.
The position keeper solved the equations of motion integrated over time. The result was a continuous prediction of where the target was at any instant. Successive measurements of the targets position keeper’s prediction and corrections for error were compared to the position keeper’s prediction and corrections smaller. It was difficult to get an accurate track on the target after about three or four observations under good conditions.
The angle solver automatically took the targets predicted position from the position keeper, combined it with the tactical properties of the torpedoes and solved for the torpedo gyro angle. Values calculated from the solution were returned two the position keeper in two feed back loops. The gyro angle automatically went to each of the torpedo rooms and was set into the torpedo tubes continuously. The TDC controlled both torpedo rooms and all two torpedo tubes at once.
The U.S navy thus had a system that would point the torpedoes at a target as the fire control problem developed. The TDC Mark ||| was the only torpedo targeting system of the time that both solved for the gyro angle and tracked the target in real time. The comparable systems used by both Germany and Japan could compute and set the gyro angle for a fixed time in the future, but did not track the target. Thus the idea of position keeper and its iterative reduction of target position error were unique to the U.S navy and represented a distinct advantage.
TORPEDO DATA COMPUTER
The war head of the Mark 15 type torpedoes is filled with a Mark17 type warhead. It is ogival in shape in its forward end and cylindrical in it’s after parts. Noise rings are provided at the forward end of the shell to facilitate handling. The shell is made of Phosphor Bronze.
The high explosive charge consists of more than 800 pounds of HBX. The lead ballast is mounted in the bottom of the war head shell, helps to control the trim of the torpedo and to minimize rolling. A joint ring at the after end of the war head is drilled and tapped for the joint screws that secure the head of the of the flask section. The after end of the shell is closed by a bulk head, which is bolted to the flange on the inner side of the joint ring. The gasket between the bulkhead and the flange forms the watertight seal. Exploder mechanism fits in a cavity in the bottom of the forward end of the warhead.
EXERCISE HEAD ACCESSORIES
The head light helps the recovery crew to locate a torpedo that has been fired at night. It contains a bulb and a set of flash like batteries. An inertia switch in the head light causes the light to turn on when the torpedo is fired on.
A torch pot helps in locating the exercise torpedo in the daytime a torch pot contains a chemical that gives of a smoke when it gets wet. A metal seal on the torch pot case is removed shortly before firing. When the torpedo is fired water enters in to the case and the torch pot begins to smoke. The depth and the roll recorder is a mechanical device that helps in the evaluation of the torpedo’s performance during exercise run. Through out the run it makes a continuous graphics record of the torpedo’s running depth and angle of the roll. A pinger is a sound making device which is sometimes used when an exercise torpedo is fired in relatively shallow water. If the head fails to blow and the torpedo sinks the noise of the pinger makes the torpedo easier to find.
EXERCISE HEAD OPERATION
When the exercise torpedo is fired the exercise head is filled with liquid ballast. The air releasing mechanism is connected to the air flask through the fitting in the exercise head, bulk head, and through blow valve on the flask. The blow valve is open when the torpedo is prepared for firing. This allows compressed air to reach air releasing mechanism. Air pressure overcomes the pressure of the spring inside the mechanism and closes its valve so that no air can enter the head section.
During the torpedo run, the torpedo constantly uses air from its air flask and the flask pressure slowly falls. When it reaches a certain predetermined level it can no longer overcome spring pressure in the air releasing mechanism. The valve opens and releases compressed air into the exercise head. Air pressure then forces the liquid ballast out through the discharge valve.
EXERCISE FIRING AND RECOVERY
Every torpedo is given at least one proof run before it is issued to the fleet. An exercise torpedo is recovered from the boat that approaches from the fleet side to prevent any danger of drifting down of torpedo. The torpedo is nearly vertical in the water because of its empty head section. A noose passed over the torpedoes nose and a line secured to the nose ring. The torpedo is towed and secured around the tail section. As a safety precaution to keep the torpedo engine from starting up again, the stop valve is closed and lock installed on the propellers as soon as these parts are accessible. The torpedo is then towed back to the firing ship.
DIFFERENT TYPES OF TORPEDOES
The Mark48 heavy weight torpedoes, the Mark48 light weight torpedoes and the Mark50 advanced light weight torpedoes are three major torpedoes in the navy inventory.
The MK46 torpedo is designed to attack submarines. The MK48 is designed to compact the fast deep diving nuclear submarines. The MK50is the advanced light weight torpedo used against faster, deeper diving and more sophisticated submarines. The MK50 will be eventually replacing the MK46 as the fleet’s light weight torpedo.
Torpedoes Mark 14 type and Mark 23 type
These torpedoes are only 20 1/2 feet long, to fit in submarine tubes. The Mark 14 has two speeds. The low-power setting will give a range of 9,000 yards at approximately 32 knots, and the high-power setting, a range of 4,500 yards at 46 knots. Its war head contains about 700 pounds of high explosive.
There are no side-gear assemblies in the main engine of this torpedo. The two speed settings are obtained by changing the number of nozzle jets in use (two for low speed, five for high) and by altering the size of the restrictions in the air, fuel, and water delivery lines.
The Mark 14 torpedo has a governor whose function is to stop the torpedo, if the starting lever is tripped accidentally, before the engine develops excessive speed, and thereby to safeguard personnel and to prevent serious damage to the torpedo. Centrifugal force actuates the governor, closing a valve in the air line from the starting piston to the low-pressure side of the reducing valve, thus banking the air over the main starting valve and stopping the torpedo’s power plant.
The Mark 23 torpedo is a Mark 14 torpedo from which the speed-change mechanism has been removed, leaving all five nozzles open. The restriction valve is locked in high power, and thus the engine can be operated at high speed
Torpedo Mark 18 type
The Mark 18 is an electrically propelled torpedo designed for use in submarines. It is single-speed, designed to run for 4,000 yards at an average speed of about 29 knots. The primary advantage of the Mark 18 is that it is wake less.
In place of an air-flask section this torpedo has a battery compartment, which contains a lead-acid storage battery, a hydrogen eliminator, and a ventilating system. The battery runs a 90-horsepower series electric motor (located in the after body) whose armature is connected by the main drive shaft and gearing to two counter-rotating propellers. Compressed air-required to close the starting switch, spin the gyro, and operate the depth and steering engines-is stored at 3,000 psi in three small flasks in the after body. The gyro is of “run-down” type. After the initial spin the air is shut off and the gyro is unlocked; the gyro wheel continues to spin of its own momentum. The war head contains about 600 pounds of high explosive.
Torpedo Mark 16 type
The Mark 16 is a single-speed 21-inch by 21 1/2-foot submarine torpedo. It is a gas-steam torpedo in which hydrogen peroxide (NAVOL), instead of compressed air, supplies the oxygen required for combustion of the fuel.
This use of NAVOL rather than air allows the Mark 16 torpedo to carry as much explosive as the Mark 15 and to have greater high-speed range, while not exceeding the Mark 14 in size.
The head section of this torpedo is similar to that of the Mark 15. The second or flask section contains a small compressed-air flask, a fuel (alcohol) tank, a water compartment, and a NAVOL tank-the last completely surrounded by the water tank. The main engine, valves, and control devices are located conventionally in the midship section and after body.
The source of the oxygen and of part of the water for the combustion cycle of these torpedoes is the NAVOL, which is a solution of hydrogen peroxide (H202) in water. Hydrogen peroxide, passing through a chamber containing a catalyst, decomposes with evolution of heat, to form water (steam) and oxygen. The oxygen unites with the fuel (alcohol) in the combustion pot, combustion being initiated by an igniter of conventional type. The resulting hot gases mix with steam and drive the main-engine turbines. Part of the steam comes from the breakdown of the H202 and part from additional water from the water compartment which is sprayed into the combustion pot to control the temperature.
By using NAVOL, the torpedoes require no air except (1) to force fuel, NAVOL, and water from their storage compartments to the combustion flask, (2) to drive the gyro, and (3) to operate the steering controls. As no air is fed to the combustion pot, no nitrogen is present in the exhaust to rise to the surface and leave the customary wake. There is, however, a small amount of no soluble gas resulting from the combustion of alcohol, which is forced out of the exhaust, leaving a very small wake that is practically invisible except in flat, calm water.
The main engine is a turbine with reduction gearing, similar in principle to the engine in a Mark 15 torpedo, but differing radically in mechanical detail. The turbine axis is horizontal instead of vertical, for which reason this engine is referred to as a “horizontal” or “H” engine, and spur gears rather than bevel gears are used for speed reduction.
Electrically set torpedoes
In the torpedoes described above, the gyro angle and running depth are ordinarily set mechanically, by inserting a spindle into the setting socket and turning it. Mark 14 and Mark 15 torpedoes have an additional socket for the speed setting. Obviously, all spindles must be withdrawn from their sockets before the torpedo can be fired.
In several modifications of the torpedoes mentioned above, and in practically all homing torpedoes, the settings are made electrically, rather than mechanically. A multi-conductor cable enters the breech of the torpedo tube, and is connected by a plug and socket to a similar cable that enters the after body of the torpedo. When the proper electrical inputs are supplied through the cable, servomechanisms in the torpedo automatically set the proper depth and gyro angle (and make the proper speed setting if the torpedo has a speed-change mechanism). At the instant of firing, the cable is automatically cut off close to the torpedo.
The electric setting system has several advantages. Its settings are relatively exact, and it eliminates several sources of error inherent in the mechanical setting system. Electric settings can be made right up to the instant of launching, since the cable is not cut until after the torpedo begins to move forward in the tube. And the electric setting system can easily be integrated with the advanced fire control systems, so that the setting signals are supplied automatically.
Except for the short length of cable that protrudes from the after body, an electrically set torpedo is identical in external appearance with mechanically set torpedoes of the same mark number
The torpedoes described above are designed to take up the course set on their gyro mechanisms, and then run in a straight line. Homing torpedoes can also follow a gyro course. In addition, a homing torpedo can search for a target, and, when it finds one, chase it until it secures a hit.
Some types can switch back and forth between gyro control, search pattern, and homing control, as appropriate. Several types of homing torpedoes are now in the Fleet, and others are in various stages of development. For security reasons, only a short and very general discussion can be given here.
At present, homing torpedoes are acoustic (operated by sound). In general, they are of two types-active and passive. The active type sends out short pulses of sound, and “listens” for echoes from the target. When an echo is detected, the torpedo steers itself toward the source of the echo. The passive type merely listens for target sounds (such as propeller and machinery noises), then steers itself toward the source of the sounds.
The homing torpedo has the same safety devices as the air-steam type described above. Its exploder is armed both mechanically and electrically, and remains safe until the torpedo has traveled a safe distance from the firing ship. The homing mechanism also has an arming feature, so that it remains inoperable (with the torpedo on a gyro course) until the torpedo has traveled through a preset distance. One or more additional safety features not found in no homing torpedoes are present in all homing torpedoes.
Homing torpedoes, almost without exception, are powered by electric motors and batteries. In shape and external appearance they are quite similar to the nonhoming torpedoes already described. Several types are somewhat smaller than air-steam torpedoes, in length, diameter, or both. And several types have a single propeller, rather than two
summer project pal|
Active In SP
Joined: Jan 2011
17-01-2011, 07:15 PM
TORPEDOES.ppt (Size: 877 KB / Downloads: 184)
Self propelled under water missiles .
Its own guidance system.
Also used as parts of other weapons.
Designed to detonate on contact or in proximity to a target.
The torpedoes used against submarines are shorter and lighter .
Fired from torpedo tube
Main section of a torpedo
Air flask mechanism/ Battery compartment
ASROC(Anti Submarine Rocket)
Functional Description of Torpedoes
Engines / Turbines / Motors
Pattern of Propulsion
Pattern of Propulsion
Zig zag / spiral
Active acoustic torpedo
To fire torpedo
Use compressed air
The tube supplies only the initial impulse for its start.
TORPEDO DATA COMPUTER
true mechanical computer
TDC mark III
two sections- the position keeper and the angle solver
ogival in shape
shell is made of Phosphor Bronze.
high explosive charge consists of more than 800 pounds of HBX.
lead ballast is mounted in the bottom
depth and the roll recorder
exercise head operation
exercise firing and recovery
DIFFERENT TYPES OF TORPEDOES
Mark 14 type and Mark 23 type
Torpedo Mark 18 type
Torpedo Mark 16 type
Electrically set torpedoes