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TORPEDO
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TORPEDO . In 18o5 See also:Robert See also:Fulton demonstrated a new method of destroying See also:ships by exploding a large See also:charge of See also:gunpowder against the See also:hull under See also:water. No doubt then remained as to the effectiveness of this See also:form of attack when successfully applied; it was the difficulty of getting the torpedo, as it was called, to the required position which for many years retarded its progress as a See also:practical weapon of See also:naval warfare. Attempts were first made to bring the explosive in contact with the See also:vessel by allowing it to See also:drift down to her by the See also:action of See also:tide or current, and afterwards to See also:fix it against her from some form of diving See also:boat, but successive failures led to its restriction for a considerable See also:period to the submarine mine (q.v.) in which the explosive is stationary and takes effect only when the See also:ship itself moves over or strikes the charge. Used in this way, it is an excellent deterrent to hostile warships forcing a See also:harbour. Spar or Outrigger Torpedo.—The limitations attached to the employment of submarine mines, except for See also:coast See also:defence, revived the See also:idea of taking the torpedo to the ship instead of waiting for the latter to gain some exact point which she might very possibly avoid. This first took practical shape in the spar or outrigger torpedo. This consisted of a charge of explosive at the end of a See also:long See also:pole projecting from the See also:bow of a boat, the pole being run out and immersed on arriving near the See also:object. Directly the charge came in contact with the hull of the ship it was exploded by an electric See also:battery in the boat. If the boat was not discovered and disabled while approaching, the chances were favourable to success and See also:escape afterwards. Against a vigilant enemy it was doubtless a forlorn See also:hope, but to brave men the venture offered considerable attractions. Frequent use of this spar or outrigger torpedo was made during See also:time to contemplate equipping their See also:fleet with this torpedo, for they had not, up to within a few years ago, adopted any loco-See also:motive torpedo. A See also:great improvement in the torpedo devised by Mr See also:Whitehead led them, however, definitely to prefer the latter and to discontinue the further development of the See also:Howell See also:system. The Whitehead torpedo is a See also:steel See also:fish-shaped See also:body which travels under water at a high See also:rate of See also:speed, being propelled by two screws driven by compressed See also:air. It carries a large charge of explosive which is ignited on the torpedo striking any hard substance, such as the hull of a ship. The body is divided into three parts. The foremost portion or See also:head contains the explosive—usually wet See also:gun-See also:cotton—with dry primer and See also:mechanical igniting arrangement; the centre portion is the air chamber or See also:reservoir, while the remaining See also:part or tail carries the engines, rudders, and propellers besides the apparatus for controlling See also:depth and direction. This portion also gives buoyancy to the torpedo. When the torpedo is projected from a ship or boat into the water a See also:lever is thrown back, admitting air into the engines causing the propellers to revolve and drive the torpedo ahead. It is desirable that a certain depth under water should be maintained. An See also:explosion on the See also:surface would be deprived of the greater part of its effect, for most of the See also:gas generated would escape into the air. Immersed, the water above confines the liberated gas and compels it to exert all its See also:energy against the bottom of the ship. It is also necessary to correct the tendency to rise that is due to the torpedo getting lighter as the air is used up, for compressed air has an appreciable See also:weight. This is effected by an ingenious apparatus long maintained See also:secret. The See also:general principle is to utilize the pressures due to different depths of water to actuate See also:horizontal rudders, so that the torpedo is automatically directed upwards or downwards as its tendency is to sink or rise. The efficiency of such a torpedo compared with all previous types was clearly See also:manifest when it was brought before the maritime states by the inventor, Whitehead, and it was almost universally adopted. The See also:principal defect was want of speed—which at first Speed.— 29 Knots to 800 Metres Gharge...__133 Lbs wet Gun Gotten WmghL_.._Il50Lbs. the See also:American See also:Civil See also:War. A notable instance was the destruction of the Confederate ironclad " See also:Albemarle " at the end of See also:October 1864. On this See also:mission Lieut. See also:Cushing took a See also:steam See also:launch equipped with an outrigger torpedo up the See also:Roanoke See also:River, in which See also:lay the " Albemarle." On arriving near the ship Cushing found her surrounded by logs, but pushing his boat over them, he immersed the spar and exploded his charge in contact with the " Albemarle " under a heavy See also:fire. Ship and launch sank together, but the gallant officer jumped overboard, swam away and escaped. Submerged boats were also used for similar service, but usually went to the bottom with their crews. During the war between See also:France and See also:China in 1884 the " Yang Woo " was attacked and destroyed by an outrigger torpedo. See also:Locomotive Torpedoes.—Though the spar torpedo had scored some successes, it was mainly because the means of defence against it at that time were inefficient. The ship trusted solely to her heavy gun and See also:rifle fire to repel the attack. The See also:noise, See also:smoke, and difficulty of hitting a small object at See also:night with a piece that could probably be discharged but once before the boat arrived, while rifle bullets would not stop its advance, favoured the attack. When a number of small guns and electric See also:lights were added to a ship's equipment, success with an outrigger torpedo became nearly, if not entirely, impossible. See also:Attention was then turned in the direction of giving See also:motion to the torpedo and steering it to the required point by electric wires worked from the See also:shore or from another vessel; or, dispensing with any such connection, of devising a torpedo which would travel under water in a given direction by means of self-contained motive See also:power and machinery. Of the former type are the Lay, See also:Sims-See also:Edison and Brennan torpedoes. The first two—electrically steered by a See also:wire which trails behind the torpedo—have in-sufficient speed to be of practical value, and are no longer used. The Brennan torpedo, carrying a charge of explosive, travels under water and is propelled by unwinding two drums or reels of See also:fine steel wire within the torpedo. The rotation of these reels is communicated to the propellers, causing the torpedo to advance. The ends of the wires are connected to an See also:engine on shore to give rapid unwinding and increased speed to the torpedo. It is steered by varying the speed of unwinding the two wires. This torpedo was adopted by the See also:British war See also:office for harbour defence and the See also:protection of narrow channels. Uncontrolled Torpedoes.—The objection of naval See also:officers to have any form of torpedo connected by wire to their ship during an action, impeding her See also:free See also:movement, liable to get entangled in her propellers and perhaps exploding where not desired—disadvantages which led them to discard the See also:Harvey towing torpedo many years ago—has hitherto prevented any See also:navy from adopting a controlled torpedo for its See also:sea-going fleet. The last See also:quarter of the 19th See also:century saw, however, great advances in the equipment of ships with locomotive torpedoes of the uncontrolled type. The Howell may be briefly described, as it has a See also:special feature of some See also:interest. Motive power is provided by causing a heavy steel See also:fly-See also:wheel inside the torpedo to revolve with great velocity. This is effected by a small special engine outside operating on the See also:axle. When sufficiently spun up, the axle of the flywheel is connected with the propeller shafts and screws which drive the torpedo, so that on entering the water it is driven ahead and continues its course until the power stored up in the flywheel is exhausted. Now when a torpedo is discharged into the sea from a ship in motion, it has a tendency to deflect owing to the action of the passing water. The See also:angle of deflexion will vary according to the speed of the ship, and is also affected by other causes, such as the position in the ship from which the torpedo is discharged, and its own angle with the See also:line of See also:keel. Hence arise inaccuracies of See also:shooting; but these do not occur with this torpedo, for the motion of the flywheel, acting as a gyroscope—the principle of which applied to the Whitehead torpedo is described later—keeps this torpedo on a straight course. This See also:advantage, combined with simplicity in construction, induced the American naval authorities at one did not exceed to knots an See also:hour—but by the application of 'See also:Brother-See also:hood's 3-See also:cylinder engine the speed was increased to 18 knots—a great advance. From that time continuous improvements have resulted in speeds of 30 knots and upwards for a See also:short range being obtained. For some years a torpedo 14 ft. long and 14 in. in See also:diameter was considered large enough, though it had a very limited effective range. For a longer range a larger weapon must be employed capable of carrying a greater See also:supply of air. To obtain this, torpedoes of 18 in. diameter, involving increased length and weight, have for some time been constructed, and have taken the See also:place of the smaller torpedo in the equipment of warships. This advance in dimensions has not only given a faster and steadier torpedo, but enabled such a heavy charge of gun-cotton to be carried that its explosion against any portion of a ship would inevitably either sink or disable her. The dimensions, shape, &c., of the 14-and 18-in. torpedoes are shown in fig. 1. A limited range was still imposed by the uncertainty of its course under water. The speed of the ship from which it was discharged, the angle with her keel at which it entered the water, and the varying velocity of impulse, tended to See also:error of See also:flight, such error being magnified the farther the path of the torpedo was prolonged. Hence 800 yds. was formerly considered the limit of distance within which the torpedo should be discharged at sea against an object from a ship in motion. In these circumstances, though improvements in the manufacture of steel and engines allowed of torpedoes of far longer range being 18-See also:INCH TORPEDO Speed ...30 Knots to 600 Yds. Gharge 115 Lbs of Wet Gun Cot'on 1q-INCH TORPEDO. We,ght_706 Lbs made (the fastest torpedo up to 1898 having a speed of 29 knots for 800 yds.), it was of no advantage to make them, as they could not be depended upon to run in a straight line from a stationary point for more than 800 yds., while from a ship in motion See also:good practice could only be ensured at a reduced range. It was obvious, therefore, that to increase the effective range of the torpedo, these errors of direction must be overcome by some automatic steering arrangement. Several inventors turned their attention to the subject, nearly all of whom proposed to utilize the principle of the gyroscope for the purpose. The first which gave any satisfactory results was an apparatus devised by See also:Ludwig Obry—an engineer in See also:Austria—and tried by the See also:Italian See also:government about 1896. These trials demonstrated the feasibility of accurately and automatically steering a torpedo in a See also:direct line by this means. Messrs Whitehead & Co., of See also:Fiume, then acquired the invention, and after exhaustive experiments produced the apparatus which' is now fitted to every torpedo made. It is based on the principle that a body revolving on a free See also:axis tends to preserve its See also:plane of rotation. A gyroscope with plane of rotation parallel to the See also:vertical axis of the torpedo will have an angular motion if the torpedo is diverted from its See also:original course. This angular motion is employed to actuate the steering mechanism by operating an air motor connected with the rudders, and keeping the torpedo in the line of See also:discharge. The apparatus consists of a flywheel caused to rotate by a See also:spring, the See also:barrel on which the latter is See also:wound having a segmental wheel which gears into a toothed pinion spindle of the flywheel. Owing to the diameter of the segment being much greater than the pinion, a rapid rotatory motion is imparted. The spring is wound up by a See also: It is placed in the after-body of the torpedo, as indicated in fig. 2.limited by the strength of the engines and other parts. Improvements in steel manufacture have permitted the use of much higher pressures of air and the construction of air-See also:chambers able to with-stand the pressure of 2000 lb to the sq. in. with the same weight of air-chamber. This has enabled increased range without reduction in speed to be attained, or conversely, increased speed at shorter ranges. By improvement in the engines which are now of the Brotherhood 4-cylinder central crank type further gains have been effected. Having reached the limit of pressure and endurance of air-chambers with See also:present materials without undue increase of weight, the designer had to seek additional energy in another direction. Now the energy obtainable from a given weight of compressed air is dependent upon the See also:volume of air available at the working pressure of the engines. At a See also:constant pressure this volume of air is proportionate to its See also:absolute temperature. If then the air be stored See also:cold and highly heated before delivery to the engine the available energy from a given weight will be greatly increased. By this means we obtain the See also:equivalent of a larger and heavier air-chamber without the increased weight such would involve. As originally used a quantity of See also:hydrocarbon See also:fuel was placed in the air-vessel. Upon discharging the torpedo this fuel was; automatically ignited and the contents of the air-chamber were heated. Unless, however, the See also:combustion could be regulated there were serious risks of abnormal pressures, of overheating and weakening the air-vessel. Devices have been applied to overcome this liability, and other methods devised to obtain the same result. By the use of See also:heating and thereby increasing the volume of air in proportion to the rise of temperature the extra volume will allow of an increased speed for a given range or a greater range without increase of speed. The limit to the development of this system seems to be the temperature the materials will stand, but even at this See also:early See also:stage it has added several knots to the speed of this wonderful weapon. Torpedo Carriages and Discharge.—As no gun which is inefficiently mounted can give good results, so the best torpedo is valueless without a good See also:carriage or system of discharge. In the early days of the Whitehead, discredit came upon it because the importance of this was not sufficiently realized; and an erratic course under water was in nine cases out of ten due to a crude method of discharge. A delicate piece of mechanism was dropped into the water from a height of several feet, and naturally suffered See also:internal derangement. Gun-ports were then used for the purpose, but now a special orifice is made, to which the torpedo carriage is fitted with a See also:ball-and-socket See also:joint—forming a water-tight See also:aperture—so that this carriage or tube may be only 2 or 3 ft. above the water-line. The ball-and-socket joint enables it also to have a considerable angle of training. Additional information and CommentsThere are no comments yet for this article.
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