Part I.
The Intrinsic Value of the Torpedo as a Weapon of Offense.
In popular discussions of the value of the torpedo as a weapon of offense, it very frequently occurs that the objective feature of the weapon is lost sight of, or becomes confused with the condition of its development, so that, because with any particular type the results hitherto obtained have been but moderately successful, doubt is expressed as to the intrinsic value of the weapon, and it is even a commonly expressed opinion that sooner or later some form of ordnance capable of discharging large quantities of a high explosive will entirely replace all torpedoes except perhaps fixed mines for the defense of channels.
In naval warfare the torpedo is as distinct a class of weapon and is as independent of all ordnance development as is the "arme blanche" (such as the bayonet, sword, etc.) from the fire-arm in military warfare. The invention of fire-arms created no new objective feature of warfare, but simply provided a means of meeting a necessity that had always existed. During the first period of the introduction of fire-arms as infantry weapons, the line of battle consisted of ranks of arquebus men and ranks of pikemen. The distinct objective features of the two weapons were confided to different corps. The invention of the bayonet enabled one corps to fulfill both features, but neither this consolidation nor any improvement, from the matchlock to the magazine rifle, or from the pike to the sword-bayonet, has in the least degree affected the objective features themselves, nor have improvements in one weapon lessened the necessity for the possession of the other.
Precisely the same conditions exist in naval warfare between ordnance and torpedoes. The former class of weapons is and can only be devoted to the attack of the above-water portions of a vessel, whilst the latter is as exclusively devoted to the under-water body. As ordnance has developed in power, the engines, boilers, steering gear, magazines and other vital elements of fighting power have been driven for safety to the under-water body, for it is there that the defense is the strongest and the offense the weakest. To leave the attack of the under-water body out of consideration simply because hitherto the development of the torpedo has been but extremely limited, is to omit a fundamental principle of offensive tactics. It has been only one hundred years since Bushnell invented the torpedo. He created no new objective feature any more than did the inventor of the arquebus. It required Cushing's attack on the Albemarle to convince the world that the feature not only existed, but was of prime importance, and from that day the development of the weapon that shall most effectively fulfill that feature has been unceasing, and in the very nature of naval warfare will continue to be.
The torpedo, as a naval weapon of offense, is a permanent weapon, and no ordnance development, no matter what be its nature, can in the slightest degree affect its existence.
Classification of Purely Naval Torpedoes.
As in the general discussion of the value of torpedoes, the absolute necessity for the existence of the weapon loses appreciation from confusing it with considerations of the state of development, so in the discussion of development, a failure to properly distinguish the natural classification leads to confusion in the attempt to compare different types.
It would be manifestly absurd to attempt to compare directly and generally a magazine rifle with a field gun, or a field gun with a mortar. Quite as distinct a classification exists amongst torpedoes. Fixed mines have a certain special field of action within which they are undoubtedly superior to torpedoes designed for other fields. Torpedoes that are propelled and guided from a fixed point, with which they are in some manner constantly connected, have also their distinct field. Torpedoes that may be classed under the head of purely naval torpedoes occupy a field of their own, for they are required to be effective in waters of an indefinite depth and under all conditions of movement of the point of discharge.
Considering only this general classification of the naval torpedo, it will be found that, as represented by development, the different types come naturally under one of the three following subdivisions:
1st. The fixed torpedo, carried and used by a vessel at a fixed and very limited distance from it, such as the Spar and the Towing torpedoes.
2d. The semi-automobile torpedo, which upon discharge is independent of the vessel, but which for range is dependent upon the force of projection, and which lacks a complete development of directive force, such as the projectile from the submarine gun.
3d. The automobile torpedo, which, independently of the vessel and irrespective of the means of discharge, maintains its speed by self-contained motive power, and its depth and direction by self-contained directive power.
These subdivisions are developments the one from the other in the order above given, and that the higher development has not rendered the lower one obsolete is due entirely to incompleteness of development. The "bag of powder on the end of the pole" so ably handled by Gushing is clearly but of a most limited efficiency, since it can scarcely be used beyond a distance of fifty feet; yet it is not entirely obsolete, because certain features which it possesses within that distance are as yet not as certainly assured in the higher developments. The projectile ejected from the submarine gun possesses elements of great simplicity, but it needs but a cursory examination to show that it is an inferior development to the automobile torpedo, for it depends upon the force of ejection entirely for its speed and range; but precisely the same force may be applied in precisely the same way to the automobile torpedo, producing exactly the same result. The automobile torpedo, however, possesses, hi addition and entirely independent of this force of ejection, an inherent propulsive and directive force, which is so much clear gain over the submarine projectile, and any attempt whatever to increase range and accuracy of the latter can only be obtained through an approach to the automobile condition. Therefore the automobile torpedo is the highest (not necessarily the best perfected) development of the naval torpedo.
The Present Status of the Automobile Torpedo.
The velocity, range and accuracy of all automobile torpedoes thus far developed are almost incomparably inferior to those of ordnance projectiles, and on this account it is frequently argued that under present fighting conditions it would be very exceptional that the condition would occur where, in action, the torpedo could be used with a reasonable chance of success. This argument is upheld by the evidence (undoubtedly true) that in the wars which have occurred since 1875, at which date the automobile torpedo became a practicable weapon, the results obtained have but a negative value. That is, whilst they may have shown possibilities of future development, there has been no instance of positive success.
That this argument is erroneous is readily susceptible of proof.
1st. We have the undoubted fact that, in spite of all failures and in the face of immense expenditures, every navy in the world not only has made strenuous efforts to develop the automobile torpedo, but the demand for this weapon and the efforts to improve it have steadily increased since the commencement, now nearly twenty years ago. Precisely as with the change from the smooth-bore to the rifled gun, from the muzzle to the breech-loader, from the cast-iron to the built-up steel gun, there is more than a simple novelty involved. The development of the automobile torpedo must go forward, for it is universally and truthfully regarded as an accessory of armament absolutely necessary. It is only necessary to go back thirty years to find the same argument used against iron-clads, or twenty-five years to find it against breech-loading ordnance, or ten years to find it against magazine rifles. The automobile torpedo is as irresistible a development as either of these.
2d. It is conceded by naval tacticians that the general fighting range in naval action will be within seven hundred yards. The automobile torpedo has, within the past five years, been so developed as to become more than a fairly efficient weapon at that range.
3d. It is the automobile torpedo, and that alone, that has forced into existence the worst hamper to effective naval fighting yet known. The net. There is, perhaps, no argument so common against the automobile torpedo as that it is useless because the net will keep it clear of the ship, and yet none is more fallacious. With precisely the same truth might it be said that guns were useless, because armor would keep out projectiles. All naval sea-going vessels now carry nets as a part of their defensive equipment. No commander would use his net in action, knowing that his opponent did not carry automobile torpedoes, and every commander will use his net, knowing that the enemy carries them. A commander without an automobile torpedo, no matter how crude, must hamper himself with a net, whilst he leaves his opponent not only unencumbered, but with a weapon capable on a chance of deciding an action at a single shot.
The conclusion is inevitable. No weapon can replace the torpedo or affect its existence and development, because to the torpedo alone belongs the attack of the under-water body. Of the naval torpedoes as above defined, the automobile is the highest class of development. Types may be more or less efficient, and the sole reason for the Whitehead torpedo having been universally accepted with all its faults is because it has hitherto been the only practicable type. Valid arguments may be made against the Whitehead, or any other type of automobile torpedo. But none whatever can be made against the automobile torpedo "sui generis."
Type Differences Between the Whitehead and the Howell Automobile Torpedoes.
The first successful type of automobile torpedo developed was the Whitehead, whose only competitor heretofore has been the Schwartzkopf, which really possesses no type difference. A distinct rival in type to the Whitehead is the Howell, and in following the discussion of the merits of type differences between these rivals, it is necessary to keep constantly in mind the fundamental definition of an automobile torpedo, which is: one that, independently of the vessel and irrespective of the means of discharge, maintains its speed by self-contained motive power, and its depth and direction by self-contained directive power.
In both the Whitehead and the Howell types the speed is maintained by the action of screw propellers. In the Whitehead the screws are actuated by an engine, whose motive power is compressed air, which is carried in a tank in the torpedo, feeding the air to the engine as a boiler feeds steam to an ordinary engine. In the Howell the screws are actuated by a heavy fly-wheel, without the interposition of an engine, the energy of the fly-wheel being the motive force. In this difference of application of motive power appears the first marked contrast of type.
The Howell contains no engine, and thus gains a very important advantage in simplicity and economy over the Whitehead. On the other hand, the motive force of the Whitehead may be kept stored in the torpedo for a certain length of time, so that, in so far as this element is concerned, when it is inserted into its launching tube, it is always ready for instantaneous discharge. The Howell, however, can only have its motive force applied or stored in it after it is inserted in its tube, so that, in so far as fighting conditions are concerned, only the first torpedo inserted can be kept in readiness for instantaneous discharge. This drawback to discharge, however, is less serious than may at first appear, for in action the first torpedo can be discharged at will at full speed. As at present developed, the launching tube may be reloaded, the fly-wheel be spun to full speed, and the torpedo be discharged as quickly as a twelve-inch gun can be reloaded and fired. At half speed of torpedo the rapidity of fire can be nearly doubled. Finally, rapidity of fire is in a very great measure due to the power available for spinning the wheel, and it is beyond all question that this power may be readily and securely applied in much less than half the time required under present conditions, so that the case will be very exceptional, indeed, where in action a torpedo will not be ready at the instant that it is wanted.
In both types the depth of immersion is maintained by a horizontal rudder, actuated by a hydrostatic piston and a pendulum. The arrangement of the combination in the two types is quite dissimilar, but there is no absolute type difference. The discussion of this element belongs, therefore, to a detailed description of the mechanism itself.
In the Whitehead, constancy of direction is maintained by means of vertical rudders, which are adjusted to suit the conditions known or estimated to exist throughout the trajectory at the moment of firing. These rudders must be set just previous to discharge. The Howell has no directive rudders or mechanism whatever, but maintains a rigid direction through the gyroscopic force of its fly-wheel.
In this respect not only does the Howell gain in simplicity in having no vertical rudders or attachments, but, what is of far greater importance, it requires no adjustment for direction before firing. In a very great measure what is gained by the Whitehead in having its motive force stored in it, so that it is ready for discharge when put into the tube, is counterbalanced by the condition that any change in speed of ship, or keel angle of fire or heel of ship after insertion of the torpedo, demands a readjustment of the vertical rudders. With this drawback to the Whitehead it is almost absolutely necessary, for full efficiency in battle, that the keel angle of fire of any single launching tube should be permanent, whilst with the Howell, since no adjustment is necessary, the launching tube may be pivoted and brought to bear on the enemy at will, with security as to accuracy in flight.
It will be readily understood that an automobile torpedo, from its general spindle shape and complete submersion, is extremely sensitive to the action of disturbing forces, either interior or exterior. The weight of compressed air carried by the Whitehead is with the smallest torpedo made more than twenty-five lbs., and during flight this weight is being constantly decreased. It is therefore quite impossible to maintain the relative positions of the center of gravity and center of buoyancy so that, no matter how exact may be the original adjustment, it will not hold throughout flight, and any variation leads to error either in constancy of depth or direction. In the Howell, the amount and distribution of weight is constant, so that this cause of error is entirely avoided.
In the Howell, the gyroscopic force gives to the torpedo great rigidity against rolling on its longitudinal axis. The Whitehead is most sensitive of all to such a disturbance, and it will be readily seen that the action of rolling directly affects the functions of the rudders, giving to the horizontal rudder a horizontal steering power. It is found necessary with the Whitehead to carry the propellers the one behind the other, mounted on middle line shafts, and it is found that as the speed of these screws exceeds or falls short of a certain normal, either the rear or the front screw tends to rotate the torpedo on its longitudinal axis. For this reason it is necessary to so regulate the supply of condensed air to the engines that the speed of the screws (and consequently the speed of the torpedo) shall be nearly constant throughout its run. This leads to a very appreciable waste of power. On the other hand, with the Howell, the twin screws are mounted on parallel shafts in the normal manner, and no regard need be paid to any difference in rotating power that one screw may have over the other; they balance themselves, and, even if from any cause they did not, the torpedo is held rigid against rotation by the gyroscopic force of the fly-wheel. This being the case, the full power of the fly-wheel is applied to driving the torpedo throughout the run, and as a consequence the speed developed over the first parts of the run may be higher than with corresponding Whiteheads, whilst at an extreme range, accuracy in direction is maintained at a low speed, which is impossible with the Whitehead.
It is considered necessary with any automobile torpedo that in case it should fail in action to strike the enemy, it should be capable of sinking automatically, to avoid the chance of being overrun and exploded by a friend. In a general action also, it is of great importance that a torpedo once discharged should not sheer wide enough from its direction of projection to endanger striking a friend. With the Whitehead, assuming that on discharge its buoyancy is negative, so that it would sink when uncontrolled by its horizontal rudder (which would be the case at the end of its run), it loses so much weight of compressed air as to give it a positive buoyancy, and therefore a special mechanism has to be introduced to allow water to enter the body of the torpedo at the end of its run and sink it. With the Howell this is not necessary, as its weights do not change, and, being started with negative buoyancy, it will sink of its own accord at the end of its run.
It may seem from a cursory examination that with the Whitehead such a disposition could be made that the loss of weight of air could be compensated by admitting water. This, however, is impossible unless the water could replace the air in position. Any attempt to do it results in aggravating the variation of the center of gravity with regard to the center of buoyancy, and with water ballast thus taken in, if the torpedo tended to roll in either direction, the water would aggravate the tendency.
As has been explained, when the speed of the screws falls an appreciable amount below the normal, a tendency to heel the Whitehead torpedo is created, and the heeling in turn sheers it broadly out of its course. Therefore, in order to avoid the danger of an erratic course, it is necessary to introduce a mechanism to cut off the air and stop the torpedo when it has run to the limit of range permissible under its constant speed. This difficulty also is entirely avoided with the Howell.
Speed is undoubtedly a most important element of efficiency in automobile torpedoes. With regard to the comparative speeds of the two types, although the Whitehead has records of speeds much higher than any attained by the Howell, it must be borne in mind that with all automobile torpedoes, irrespective of type, speed is in a great measure a function of displacement. The largest Howell torpedo yet built is smaller than the smallest Whitehead used.
There is no valid reason why, for equality of displacement, the speed of the Howell should not be fully as great as that of the Whitehead, and also capable of as much future development. In the compartment division, section-fastening, bulk-heading, bracing, arrangement of charge and position of details, there is scarcely a single point of resemblance between the Whitehead and the Howell. These details, however, can scarcely be classed as typical, nor can they be compared and their merits be discussed except in the course of detailed description.
Part II.
General Description of the Howell Automobile Torpedo.
Plate I.
The general profile of the Howell torpedo is that of a spindle of revolution, the after-body being a true spindle, the middle body a cylinder, and the fore-body an approach to an ogive. There are four distinct and detachable sections: the nose, A. A., which carries the firing-pin and its mechanism; the head, B. B., which carries the explosive charge and detonator; the main section, C. C., which carries the fly-wheel and screw gears; the stern section, D. D., which carries the diving mechanism.
The Nose.
Plate I.—Figs. 2, 3 and 4.
In order to guard as completely as possible against a premature discharge of the torpedo in handling, the percussion firing-pin is so arranged as to be completely removable, and also to be quickly attached at the last moment before inserting the torpedo in the launching tube. If the pin alone were made removable, as it is but a small accessory, it might be overlooked in the heat of action. Also, if any preliminary manipulation of the mechanism were necessary to get it into proper condition for firing, an error or omission might be made. The entire firing-pin mechanism is therefore permanently fixed in a single hollow bronze casting 17, 17, which is attached to a projecting lip at the front end of the head by a simple bayonet joint, so that a few seconds only are necessary to attach and detach it.
The United States naval specifications for firing-pins of torpedoes demand more functions and greater security than have heretofore been required. When attached to the torpedo it must be locked safe from discharge whilst handling the torpedo and previous to launching; it must arm itself for firing automatically after launching; it must act if striking an opposing body at an angle of fifteen degrees from its axis; it must automatically lock itself securely at the end of the run of the torpedo. These functions are performed by the following arrangement of mechanism: a stout steel pin, 18, travels in guides formed in the nose casting, and is actuated by a strong spiral spring, 19. It is held back in the armed position by a soft metal pin, 20, which seats in a slot cut through the pin, and bears against the outside of the nose. The outer end of the firing-pin is provided with fan-shaped corrugated horns, 21, which receive the impact blow, and are so shaped and arranged as to prevent glancing or sliding along the object struck when the impact is sharply angular. The force of the blow is intended to shear the soft metal stop-pin, and thus permit the firing-pin to be driven violently down on the detonator by the spring.
Two small cams, 22, 22, are so pivoted and maintained by the small flat springs 23, 23, that normally they rest against the body of the firing-pin just under a shoulder, so that if from any accident the pin after cocking should be so struck as to shear the soft metal stoppin, it could not drive down and explode the detonator. Just in front of the cams is a cross-head, 24, having projections which rest on the cams so that as the cross-head is pushed to the rear the cams are turned out clear of the shoulder, leaving the firing-pin clear. The cross-head is in turn in connection with two small pistons, 25, 25, which are held forward by the cam springs. The front ends of these pistons come out flush with the outer surface of the nose and are entirely open. When, after launching, the torpedo strikes and rushes through the water, the direct pressure on these pistons forces them back against their springs, in turn pressing on the cams and turning them back clear of the firing-pin, which is then completely armed for action. When the speed of the torpedo becomes so reduced as to permit the piston springs to overcome the pressure of water on the pistons, they come forward, the cams turn in under the shoulder, and the firing-pin is again locked. The condition of the firing-pin is at all times plainly visible. The soft metal stop-pin is on the outside, where its condition is always visible. The length of the firing-pin projecting beyond the nose shows whether it is cocked or not. The piston heads being plainly visible, show at all times whether the cams lock the pin or not. Except the fingers be deliberately used to push the pistons back, the firing-pin cannot be unlocked in handling the torpedo. Finally, all parts are secured in the single nose, and in such a way that absolutely no preliminary work is required. At the last moment the nose-piece is secured to the head by a simple twist of the bayonet joint.
It is to be remarked that when the nose is off the head the front of interior of the head is laid bare, so that the detonator itself may be kept out of the torpedo until the last moment. Small holes, 26, 26, inclining strongly backward are pierced through the nose and are left open. These holes leak water into the hollow nose-chamber when the torpedo is stationary or at low speed, which overcomes the reserve buoyancy of the torpedo, sinking it, and finally attacking and drowning the dry gun-cotton detonator, so that if the torpedo fails to make a hit, it locks its firing-pin, sinks and drowns its detonator, being thus rendered completely innocuous.
The Head.
Plate II.
In order that the explosive charge of the torpedo may be readily attached and detached, be stowed compactly and safely in a magazine, and at the same time that the torpedo may be used with perfect safety in exercise, it is provided with two distinct heads that correspond exactly in profile; the nose being interchangeable with either head, so that the firing-pin may be used both in exercise and in battle, and the connection between the head and the main section being precisely the same with both. These heads are distinguished as the dummy head and the fighting head.
The shells of both heads are made of a single sheet of brass brazed and spun to shape and braced by bronze rings, A. A. B. B., at the front and rear ends. Each of these rings is prolonged slightly beyond the end of the shell to form bayonet joint locks, the front one for holding the Nose, the rear one for securing to the Main Section.
The dummy head carries a heavy wooden block, C. C, quite filling the interior space. This block has a square hole cut through its axis and carrying an iron threaded bar D. D. Upon this bar is a square lead block E. E. The inner end of the bar being squared, it is readily seen that by turning it the block is traversed back and forth. By this means the torpedo is balanced longitudinally. It is necessary here to explain that when the torpedo is launched, no matter whether it has buoyancy or not, its diving mechanism will keep it at its proper depth. It is desirable that the greatest weight of explosive possible should be carried, and also, as has been heretofore explained, that it should sink at the end of its run if it fails to make a hit. Therefore, with the fighting head the buoyancy is practically nil, and the torpedo is permanently balanced in its entirety for this condition. For exercise, however, the torpedo must not be allowed to sink, as it would be lost. The dummy head, therefore, is lighter than the fighting head, so as to give about thirteen pounds buoyancy, and the lead block is introduced in order to give a long arm to a compact heavy weight in the section that is not water borne, so as to keep the center of gravity of the torpedo in the same position relatively to the center of buoyancy as that occupied with the fighting head. Otherwise there would be a difference of leverage between the two conditions that would alter the steering adjustments. A single shop adjustment of this block is sufficient, and it maintains its place unless moved by screwing the bar.
A complete bulkhead plate screws water-tight into the rear end of both heads.
In the fighting head, the main part is completely filled with wet gun-cotton, a small water-tight chamber, F. F., formed of a single piece of drawn copper being reserved for the dry gun-cotton primer. This chamber is removable, having a flange G. G. at its mouth, which seats on a diaphragm H. H. screwed across the mouth of the front casting by means of a ring I.I. screwing down on a rubber gasket. A cap K. K. covers the -primer chamber, being held in place by spring catches L. L., and forming also the seat for the detonator M., which is held in place by the spring catches N.N.
By this arrangement the detonator may be removed, and, as the dry primer is contained in a thin tin case, it also is readily removable, leaving the head with only the wet gun-cotton charge, which itself is at all times hermetically sealed in proper shape for stowage in a magazine, the primer and the detonator also stowing separately in their own magazines.
Two small holes O. O. are drilled through the cap of the primer compartment, and are filled with a substance that is soluble after long contact with water. As above explained, the holes in the nose admit water at the end of a run. The water attacks the composition, filling the holes in the cover, and after a number of hours dissolves it out, and so drowns the dry gun-cotton primer.
The Main Section.
Plate I.
This section comprises the entire cylindrical body of the torpedo and portions of the curved part at either end. The shell consists of three sections of brass plate corresponding to the cylindrical and curved portions, brazed and spun to shape. The section is closed water-tight at both ends, and contains the fly-wheel with its frame, the propeller gears and forward sections of shafting, and the thrust bearings.
The shell is braced against deformation or crushing by six rib rings. A bulkhead ring, 1.1, which is flanged, and in which are worked the sockets of a bayonet joint, by which the head is secured to the main section. The flange of this ring is threaded, and receives a complete water-tight bulkhead plate, 6. In all automobile torpedoes heretofore constructed, great difficulty has been encountered in making section joints water-tight to resist the great water pressure due to depth of immersion, and in order to secure this very important feature, it has been found necessary to make a junction so complicated as to make it not only a matter of difficulty to separate the sections, but, on account of the wear from frequent joining and disjoining, the torpedo could not be taken apart and put together as desired. This feature has been overcome in the junction of the Howell section in a very simple manner, so that at this important joint the dummy and the fighting head may be quickly exchanged and without danger of compromising water-tightness. As has been described, there is a complete bulkhead plate at the rear of the head and another at the front of the main section. These plates naturally he on either side of the joint, and when the sections are connected they are only about a hundredth of an inch apart. The space is so small that any leak that may occur through the joint does not admit water enough to be of any consequence, and so long as the joint is reasonably tight, the pressure due to immersion is relieved from any water that may lie between the bulkheads, so that it will not be forced past their joints. The torpedo has been sunk to a depth of forty feet without showing any signs whatever of leakage.
Two intermediate rings, 2. 2. 2. 2., are inserted under the brazed joints of the shell. These are simply plain, flanged, bronze rings. Two rings, 3.3.3.3., support the midship section and at the same time form a part of the assemblage of the wheel frame, the other members of the frame being two plate castings, 4.4. (shown in Section Plate III., F.F.F.F.), forming the bearings for the fly-wheel, which are bolted to the rings. Finally, a rear bulkhead ring, 5. 5., which, like the front one, holds a complete bulkhead, 7. 7., and also forms the seats for the thrust bearings, 8. It is impossible to connect the main and stern sections by a bayonet joint on account of the screw shafts, which prevent the twisting necessary to lock the joint. The strengthening ring of the stern section, therefore, has a lip which fits into an undercut in the flange of the main section ring and is held by screws, 6". 6". 6". As this joint comes in the compartment containing the diving mechanism, which must be free to water access, it is not necessary that it should be water-tight.
The Fly-Wheel And Its Connections.
Plate III.
The fly-wheel, A. A. A. A., is of gun steel, drop-forged and treated similarly to the tube and jacket forgings of guns. It has a heavy rim with a solid web connecting to the hub. Secured to the hub and symmetrically placed on each side of the web are two steel miter wheels, B. B. B, B., which gear into similar wheels, 9. 9., Plate I., secured to the inner ends of the screw shafts, the proportion of gearing being as five to four, so that each screw makes 800 revolutions to every 1000 of the fly-wheel. The axle of the fly-wheel, C. C. C, is a single solid steel axle, permanently secured in its seat in the wheel, its bearing ends resting on hard steel rollers, D. D. D. D., in hard steel bearings, E. E. E. E., which themselves seat in sockets cast in one with the frame plates, F. F. F. F. The inner ends of the bearings, E.E., and the bodies of the miter-wheels facing them are grooved and hold steel balls, G. G. G. G., forming ball bearings to take the end thrust of the fly-wheel. Thus the wheel is provided with frictionless bearings, no matter what be the plane of the axle when rotating.
The connection between the fly-wheel and its motor, which forms part of the launching gear, is made through the starboard side of the torpedo by means of clutch couplings to the end of the axle. The right-hand end of the axle is squared, and carries pinned on it a steel end clutch, H. A loose clutch, I.I., is held in a stuffing-box, A'.A’, seated in a prolongation of the frame plate which bears against the shell of the torpedo, a through-hole being cut in the shell and the joint being closed water-tight. This loose clutch, I.I., is so made in order to free the fly-wheel from the friction of the clutch in the stuffing-box. After spinning up the wheel, the moment that the motor is unclutched this loose clutch commences to hang back from its friction in the stuffing-box. This brings the rear sides of the clutch studs in bearing, and as they are cut with a steep slope, the clutch is instantaneously driven out free of the wheel.
In order to preserve the balance or symmetry of the torpedo, the left-hand frame plate is carried out to the shell in the same way as the right-hand one. The interior of this projection is threaded, and a lead disc, L. L., is screwed in to counterbalance the clutch and stuffing-box on the right-hand side. By means of this lead disc alone the entire torpedo is balanced transversely, for a small hole is tapped through the shell, through which a key may be inserted and the disc may be screwed in or out to make the necessary adjustment. Once made, it remains of itself.
Plate I.
The screw shafts proper end at the bearing lo, being secured to the axles of the miter-wheels, 9.9., by a mortise and tennon connection. This is done with a double object—first, to prevent any skew tendency in the miter-wheel being transmitted to the shaft, and second, to enable the shafts to be entirely disconnected from the contents of wheel frame. In order to neutralize the skew tendency of the miter-wheels, their short axles are held in close bearings in front of and behind the wheels, these bearings forming a part of the wheel frame castings, so as to remain constantly true. The screw shafts are carried straight to the rear through the box 8, forming apart of the rear bulkhead ring, and within which are thrust bearings and a stuffing-box, made necessary by the proximity of the free water compartment. The thrust bearings being placed here have a double advantage. They relieve the miter-wheels of all thrust, and more room is allowed to make stout bearings than if they were placed farther aft.
A broad, stout plate, II.II is soldered to the bottom center of the shell, to which, on the outside of the shell, is bolted a long stud, 12. (S. Plate IV.). The function of this stud is to center and guide the torpedo in the launching tube.
Plate I.—Fig. 5.
The composition of the thrust-bearing and stuffing-box is as follows: Long seats, a. a., are cast in one with the rear bulkhead ring, over which screw caps, b. b. The shaft is slightly increased in diameter at the point c, forming a seat for the steel bearing ring d.d., which has a companion bearing ring, e. c, seated against the sleeve. Steel balls lie between these rings, thus forming a ball bearing. A bronze spanner clasps each of the caps and prevents them from unscrewing, while at the same time it resists any tendency to flexure or spreading of the shafts.
A small bronze loose sleeve, f.f., is slipped on the shaft and lies in the stuffing-box section. This sleeve is pierced with holes and its ends are packed. In this way the stuffing-box is formed, and at the same time provision is made for oiling the bearings, for the oil coming down on the sleeve passes through the holes and is absorbed and distributed by the packing.
The Stern Section.
Plate I.
The stern section is divided by a water-tight bulkhead, 13. 13. 13, into two compartments, the forward one containing the diving mechanism and being open to the free access of water through the inlet holes, E. E. E., pierced through the shell, whilst the rear compartment is closed water-tight and is empty, save the sleeves passing through it, within which are the screw shafts and tiller rods. The rear end of this section is closed by a casting called the tail-piece, 14, which forms in one the butt of the tail and the screw shaft tubes with their cross support E. E. E. E. The screw shafts are taken in bearings in the tubes E., and the screw propellers, which are right and left-handed, are screwed to the ends of the shafts, being held fast by end nuts, G. G., which are shaped off in long cones to give a fair run to the water passing the hubs. The triangular spaces, If. H., between the tail body and the screw shaft tubes are covered with plates in order to give a fair flow of water to the rudder and screws. The small chambers thus formed give additional buoyancy also.
The rudder, I.I., is a steel rectangular plate completely filling the space between the outer ends of the screw shaft tubes. In this position it is secure against damage in handling the torpedo and fouling in running. A stout web, 15. 15, stands at right angles to the plane of the rudder, forming a steering yoke, to the ends of which are pivoted the tiller rods, 16. 16, which in turn are directly connected with the diving mechanism.
The Diving Mechanism.
Plate IV.
The bulkhead, A. A. A., separates the rear and water-tight compartment from the diving compartment, both being in the stern section. It is a single casting so shaped as to reduce the water space to the least possible dimensions consistent with the working of the mechanism, and has a broad flange seating on the shell to form a stout stiffening member of this part. The bulkhead, B. B. B., which is the rear bulkhead of the main section, forms with A. A. A. a complete water chamber. The tiller rods, C. C. C. C, are pivoted to the rudder yoke, D. D., and pass, inside of sleeves, through the watertight compartment and bulkhead, their inner ends pivoting directly to their respective parts of the diving mechanism, the upper rod being attached to the hydrostatic piston, E. E., and the lower one to the compound lever of the pendulum, E. G. H. These tiller rods are provided with screw junctions, I.I., for taking up lost motion and regulating the angle of the rudder.
The forward compartment being in free connection with the exterior water, the pressure due to depth of immersion is fully borne on the piston, E. E. This piston fits loosely in its cylinder, K. K., which is secured to the bulkhead by the posts and nuts, L. L. The posts are made hollow and connect with the interior of the cylinder, so that there is free air connection between the space in the cylinder behind the piston and the whole air space in the rear compartment, so as to prevent any back pressure on the piston. A rubber disc covers the piston, and is held water-tight about its edges so as to prevent water getting into the cylinder and at the same time offer no opposition to the free movement of the piston.
Near the front end of the lower tiller rod a seat, M. M., is fastened to it, against which abuts the forward end of a powerful spring whose rear end seats against a movable sleeve, N. N. This sleeve screws into the rigid main sleeve of the rod, and a key may be used on the end outside the torpedo to screw it in or out and so alter the tension of the spring which alters the depth of immersion.
Assume that the depth at which it is desired to run the torpedo is ten feet, and that at that depth the total pressure on the hydrostatic piston due to the head of water is one hundred pounds. The rudder being held amidships, let the spring be adjusted to a tension of one hundred pounds. Since the tillers are directly connected, the one to the piston and the other to the spring, it follows that if a pressure of one hundred pounds be brought on the piston, the tension of the spring will be balanced and the rudder will lie amidships. This will occur at the assumed depth of ten feet. If the immersion be less, there will be less pressure on the piston, and the spring will hold the rudder partially down and so steer the torpedo down to its proper depth, and vice versa. It should be noticed that the tension of the spring varies inversely as its length, whilst the pressure on the piston varies directly with the depth. Therefore the helm is not thrown hard up and hard down as the torpedo departs from her proper depth, but it is eased over the proper amount to bring her easily to her proper depth. The point at which the helm is thrown hard over depends upon the length and strength of the spring, and as by specification requirements the torpedo must run within two feet of her set depth, the hard-over point is made slightly greater.
As a matter of course the torpedo will always move in the direction of its longitudinal axis. Whilst therefore through the action of the hydrostatic piston the rudder will be brought to a neutral position at the proper depth, the torpedo must be horizontal at that depth or it will continue to go down or up, according to the direction in which it points. The piston cannot correct the direction of the axis of the torpedo except secondarily. It is therefore necessary to introduce an element that shall counteract every tendency of the longitudinal axis to leave the horizontal, and this element is the pendulum.
A heavy pendulum, H., is suspended so as to swing in the fore and aft-line of the torpedo. We may say, therefore, that whenever the axis of the torpedo dips down or up, the pendulum swings forward or aft. The bob of the pendulum, which is very heavy, is mounted on springs, O.O., on its suspension rods, so that when the torpedo strikes the water in falling from a height, the shock on the suspension points will not be too severe. The pendulum is connected with the front end of the lower tiller rod by a compound lever, F. F., so as to increase its power. Assume that the torpedo is at its required depth, its axis horizontal, and its rudder amidships. Leave, for the moment, out of consideration the action of the hydrostatic piston, and assume that from any cause the bow of the torpedo is tilted down. The pendulum bob at once swings forward, and in so doing pushes the tiller rod back and forces the rudder up, thus tending to bring the torpedo to the horizontal again.
An examination of the combined action of the piston and pendulum shows a valuable feature. If the torpedo be pointed away from her proper depth line, and so long as she is leaving it, both piston and pendulum work the same way on the helm and combine their efforts to turn her back, but when she turns back, they commence to work against each other so as to ease her gently to her proper line, thus preventing violent oscillation.
This type of mechanism possesses several features of undoubted superiority over other automatic types, the most important of which are:
1st. In other types, whilst the mechanism controls the movement, the power necessary to operate the rudder and overcome friction of the working parts is taken from the motive power of the torpedo. All this power is a direct loss to driving power, reducing either speed, or range, or both. In this type the entire steering power is within the mechanism itself, releasing just that much of motive power to be used in driving the torpedo.
2d. When a torpedo strikes the water, no matter what the position of the rudder may be, it will receive a violent shock from the impinging water. The pendulum, also, will receive violent impulses both from the shock of discharge of the torpedo and the shock of taking the water. In this type it will be noticed that when the torpedo is ready for discharge, since there is no pressure on the hydrostatic piston, the pendulum is drawn by the spring hard back against a small stop, P. It there has a proper and secure bearing against discharge shock. Upon striking the water the rudder is driven up and the pendulum is driven forward, but it will be noticed that the spring receives and eases both shocks, while, moreover, both act in the same direction on the tiller rod. That is, the upper movement of the rudder corresponds with the forward movement of the pendulum. No part is therefore submitted to an undue strain.
3d. The entire mechanism from its front end to the rudder yoke is within a length of two feet and is direct-acting. The force applied to the rudder is always a balanced one of give and take on equal arms each side of the rudder, instead of being all on one side, as in other systems. There is, therefore, less lost motion and a more direct application of power. The importance of this feature will be appreciated when it is considered that in any torpedo the extreme tiller-rod movement from hard up to hard down is never as much as half an inch.
4th. Owing to the compactness of the mechanism and its situation in a section of very small diameter, the water space, which represents a clear loss of buoyancy or carrying power of the torpedo, is reduced to a minimum.
5th. All adjustments are simple, direct, and are made from the outside. The depth of immersion may be altered, lost motion be taken up, and the throw of the rudder be adjusted without the necessity of touching anything inside of the shell.
Finally, by removing the stern section the entire mechanism is laid bare and can be removed or altered without trouble or interfering with any other part of the torpedo.
The Dow Steam Turbine Motor.
Plate III.
Rotation is communicated to the fly-wheel by means of a steam motor which is a permanent attachment of the launching tube. The body of the Dow motor is a small cylindrical box about 8.75 inches in diameter by 4.5 inches in depth. The shell consists of a bronze casting, a. a. a. a., having covers, b.b.b.b., through-bolted to it, which have projections cast in one with them to form bearings for the main shaft. Two discs, c. c. c. c, screw permanently into the wall of the shell, having in turn two smaller discs, d. d. d. d., screwed into and forming a part of them. The interior of the motor is thus divided into three chambers, of which the central one, e. e., receives the live steam direct through the steam pipe (not shown in the figure), and the two outer ones, f.f.f.f., take the exhaust steam which passes out of the motor through the exhaust pipe g. The main shaft, h. h. h., is journaled in the bearings formed in the covers and is given a longitudinal play, so as to permit clutching with and unclutching from the machine required to be driven. A sleeve, i. i., covers the central part of the shaft, being keyed to it, but having a slight independent longitudinal play, and to this sleeve is secured a steel disc, k. k., which partially divides the live steam chamber. Two bronze discs, l.l.l.l., are also secured to the sleeve, and it is these discs that are revolved by the action of the steam, transmitting rotation to the main shaft.
Concentric ribs are cut on the opposing faces of the pairs of discs, c. c. c. c. and l.l.l.l., which intermesh, and through these ribs a number of angular slotways are cut, those on the stationary discs being at an opposite angle from those on the revolving ones. The live steam entering the steam space e. e. passes into the space m.m.m.m., and thence outward between the pairs of discs through their slotways, communicating rapid rotation to the revolving discs and shaft by expansion. After thus performing work, it passes into the exhaust chambers, f.f.f.f., and out through the exhaust pipe. In passing outward through the slotways the steam undergoes seven expansions.
The function of the steel disc k. k. is to balance the work done by the two pairs of discs, since practically there are two motors or drivers mounted on a single shaft. Assume that for some reason the right-hand disc is driven harder than the left-hand one. The overpressure will force the right disc, and with it the sleeve and other discs, to the right, and by this movement the steel disc partially closes the right-hand steam entrance to the chamber m.m., opens and gives more steam to the left-hand one, and thus automatically equalizes the driving force on the two revolving discs.
The left-hand end of the main shaft ends in a clutch, n., and its journal, o. o., is free to move longitudinally, carrying the shaft with it. The longitudinal clutching movement is communicated to the shaft by the study, which works in a guide-slot cut in the starting gear. (See Plate V.) The right-hand end of the shaft projects slightly beyond the end of the cover of the motor, and is hollowed to receive the squared end of an auxiliary shaft, which forms part of the tachometer.
The Elwell Tachometer.
In such high speeds of rotation as are given by turbine motors, it is of great importance that a reliable speed indicator should always be attached. The Elwell tachometer is the most exact one known. Its indications depend upon the pressure of a column of oil acting upon an ordinary steam gauge, the dial plate of the gauge being marked in thousands of revolutions per minute. The pressure created on the column of oil is due to centrifugal force applied to the oil by the rotation of a small centrifugal pump. The body of the support of the gauge is a brass casting, r. r. r., whose inner end forms a collar clasping the end of the outer shaft bearing and tightened by a screw-bolt at s. The small hand-wheel 1.1. attached to the auxiliary shaft does not belong to the tachometer, but is used when clutching up to engage the clutches. The cap u. u. screwing over the outer end of the support casting forms a small oil chamber connected with the tachometer gauge by the pipe w. Within this chamber and secured to the auxiliary shaft is a small cylinder having radial slits cut through it similar to the radial guides of a turbine wheel. As this cylinder is rapidly rotated, these slits force the oil out against the sides of the chamber with a pressure proportional to the centrifugal force developed, which itself is proportional to the speed of rotation. The pressure is communicated through the pipe w. to the gauge and acts on the pointer. The small conduit x. x. leads to an oil reservoir. y.y., which keeps the pump chamber constantly full of oil.
z.z. are oil cups for supplying oil to the main shaft bearings of the motor.
Part III.
Launching Gears.
Although, in judging of the perfection of development of any type of automobile torpedo, its means of discharge is left out of account, this latter is so important an accessory that much of the efficiency of the complete weapon depends upon its own completeness.
In the first attempt at perfecting the torpedo the delicacy of its mechanism forbade the employment of any means of discharge by which a sudden shock should be given. Nor could a torpedo be successfully launched from a height above water owing to the shock of impact and the tendency to dive very deeply. Compressed air therefore was resorted to as the expulsive force, and the point of discharge was brought as near to the proper depth line as possible. Both of these elements involved great difficulties of practical application. Compressed air discharge required complications of accessories and of details of the launching gears themselves. As the mechanism of the torpedo became simplified it was made less sensitive to shock, until finally gunpowder has been introduced for direct discharge; but hitherto this has possessed many drawbacks of its own which are very difficult of modification, amongst which the principal are: liability to derangement of the working parts of the torpedo from the impact of unburned grains of powder or the penetration of the powder fluids into its interior; fouling of the bore of the tube; danger of abnormal pressures in some part of the tube, due to a defect in the cartridge or the powder, as happens at times in guns.
In so far as the conditions of discharge themselves are concerned, it must be borne in mind that no matter how efficient a discharge may be, so long as the vessel from which it is made is stationary, such efficiency is no criterion whatever of results to be obtained with a vessel moving. Under-water discharge presents no difficulties whatever when made from a stationary point, but when made from a vessel at speed the drawbacks are very great. In beam fire from a vessel in motion it is apparent that the moment the nose of the torpedo shows beyond the end of the discharge tube, it will be swept violently aft, thus destroying the aimed direction entirely, and endangering the rear end of the torpedo, which may become jammed in the mouth of the tube. To counteract this defect it is necessary to project the guide-bar beyond the tube which will hold the torpedo in line until it is clear of the ship, and then let it go square or even. In straight-ahead fire a difficulty of another kind is met with that, it may be said in passing, is fatal to the success of the submarine gun.
Consider a torpedo discharge tube mounted in the keel line of a ship, under water, its front end open and the ship going ahead at speed. The water inside of the tube has a pressure upon it due to the speed of the ship, but it has no flow, and if a body be placed within the tube it will move with the ship, for the water in the tube has an absolute velocity equal to that of ship. The moment, however, that this body is moved forward and leaves the tube, it enters water having no motion with the ship, and at that moment the body becomes deprived of the driving force due to the speed of the vessel. Whatever be the absolute speed of discharge of the body, if it have no inherent propulsive force it will at once commence to lose speed from the resistance of the water, whilst the ship maintains her speed of advance, with the result that in the case of a submarine projectile, the ship will certainly overrun it. The same thing will happen with an automobile torpedo, unless its screws get a full driving power very quickly and give the torpedo a continuing speed, at least as great as that of the ship.
The moment that the keel angle of the discharge tube is altered to bow or beam fire, the difficulty explained as pertaining to beam fire begins to show itself. Here, then, are under-water difficulties of a most serious nature, entirely caused by motion of the point of discharge, and entirely absent when that point is stationary.
In so far as concerns the necessity for using a guide-bar to keep the front end of the torpedo from being violently swept aft in bow or beam fire, the Howell torpedo requires the application fully as much as the Whitehead. For straight-ahead fire, however, the Howell has a decided advantage over the Whitehead in that, previous to discharge, its screws are already working at full speed and commence to drive the torpedo from the instant it starts forward, so that in clearing the tube there is no check to the speed as occurs to the Whitehead, and consequently no danger of overrunning it.
In above-water discharge, as the Whitehead has no inherent directive force, every effort possible must be made to neutralize tendency to sheer. In beam or bow fire, if either the bow or stern strikes the water first, that end will be swept aft, or, what amounts to the same thing, its forward movement is checked, and consequently the torpedo is given a broad sheer. To counteract this, three precautions have to be taken: It is necessary to attach a long bar or spoon to the mouth of the discharge tube, to which the torpedo hangs itself in coming out and so is made to drop horizontally. If the ship happens to be rolling, the torpedo should be discharged at the moment when she is vertical, but even this will be ineffective if the torpedo has to strike into a wave. The angle of aim cannot be direct on the object to be hit, but allowance must be made for the inevitable sheer of the torpedo, which is always an uncertain amount. Finally the vertical rudder must be set to partially correct a rank sheer. This correction, however, is only of value to a certain point, as beyond it the torpedo will sheer in the other direction.
The inherent directive force of the Howell torpedo quite obviates all these difficulties. No projecting spoon is required on the discharge tube, the aim is direct, and no heed need be taken of rolling, heeling or wave surface.
For straight-ahead fire above water, the chances of being overrun are the same in both the Whitehead and the Howell, as in both the driving power of the screws takes effect at the same time. It is an odd accident that in under-water fire the Howell has the advantage of the Whitehead in straight-ahead fire, and the two are equally handicapped in beam fire, whilst above water the conditions of advantage and equality of the Howell are reversed.
The Elwell Launching Gear.
The launching gear designed by Mr. Elwell, the Superintending Engineer of the American Branch of the Hotchkiss Ordnance Company, possesses a striking feature in the application of the expulsive force. The medium of discharge is gunpowder, but it is so applied that the explosive shock is cushioned against the torpedo, no fouling or solid particles enter the discharge tube, and although ordinary black powder is used, the discharge is practically noiseless and smokeless. The cartridge itself is also in the simple form of ordinary metallic cartridge case ammunition.
Discharge tubes differ in general arrangement, depending upon their emplacement; that is, whether under or over water, and whether fixed or pivoting. With the exception of the accessory features, however, a description of one apparatus will serve for all, as with all gears used for the Howell torpedo every effort is made to maintain as close a similitude as possible.
The Center Pivot Launching Tube.
Plate V.
This gear is designed for open-deck emplacements, where all-around fire is permissible.
The discharge tube is of bronze, bored to a diameter five hundredths of an inch greater than the midship diameter of the torpedo (14.25 inches for the general service torpedo). It is mounted upon a low, broad cone, A. A., whose base rests on a bed-plate, B. B., bolted to the deck, the two being held together by a stout clip-ring, C. C., so that the cone is free to revolve. The interior of this cone may be fitted with a rack and gears, so that the tube may be aimed from a conning tower if desirable. A shallow groove, s., Plate III., is cut the full length of the tube along the bottom of the bore to carry the guide-stud of the torpedo. The rear end of this tube is closed by a door, D. D., hinged to swing laterally, its inside edge being coned and ground to close air-tight. A steel cross-bar, E. E., with a tightening screw, F., through its center, is carried by the same hinges as the door, the free end of the bar being held by a stout bronze loop, G. G., when the door is closed. To lock the door, it is closed, the loop is swung over the end of the bar, and a few turns are given to the tightening screw.
Two brass air tubes, H.H.H.H., are secured to the main tube underneath, one on each side, being connected together at the front end by a cross-pipe, I. The tube on the right-hand side, called the firing tube, has screwed to its rear end a small bronze breech piece, K. K., which is chambered to carry an ordinary metallic cartridge case, and has a simple breech-block, L. L., in which is fitted a hammer, sear and main-spring. The weight of powder used is less than half a pound, with which a discharge speed of over thirty-five knots can be obtained for a torpedo weighing nearly five hundred pounds. The front ends of both air tubes are closed by screw-caps, M., that may be removed whenever necessary to sweep out the tubes. It will be noticed that the forward end of the firing tube is extended well beyond the cross-duct, I. This is done in order to form a. lodgment for bits of wad or unburned grains of powder that by the explosion will be driven past the duct and be caught and held in this space, precisely as is the case with the cinder trap of a locomotive engine.
The rear end of the left-hand pipe, called the compression pipe, connects by an elbow with the main tube. Around the rear of the main tube is secured a hollow strap, N. N., into which the elbow of the compression tube opens. The wall of the tube underneath this strap is pierced all around with small square ports cut at an angle, such that the blast of air created by the explosion of the charge will be directed against the door of the tube first, instead of being taken directly on the tail of the torpedo. The air pressure thus created in the main tube drives the torpedo out. At a speed of ejection of about thirty-five knots, a torpedo discharged at a height of about five feet will take the water fully thirty feet from the ship's side.
It is well at this point to call attention to a feature of torpedo use of great importance as affecting over and under-water discharge, that has hitherto not received noteworthy attention. A ship going into action probably will find it necessary to use her net, and if she is only provided with under-water tubes, all her torpedo fire is cut off by the net, whilst if she has tubes above water, she may discharge clear over the net.
The Dow motor is attached to the main tube on its right side, a hole being pierced through in the clutch-line. The steam pipe, O.O., and the exhaust pipe. P., to and from the motor, are carried down into the supporting cone, where a junction box is made, so that the steam pipe goes through the deck inside of the exhaust. This junction is swiveled to permit the system to revolve.
A throttle valve, with a hand-wheel, R.R., gives steam, which is controlled by a regulator valve, S., and there is also connected to the throttle an automatic cut-off.
It is of great importance that, once the torpedo is in the tube in place, the work of clutching, spinning up, unclutching, cutting off steam, freeing the torpedo and discharging it, should all be done in a simple manner, quickly, and with absolute certainty of the proper succession of movements. This work is almost entirely automatic, and is done in the following manner: The small box, V., is a steam cylinder whose piston projects up through the main tube into and filling the slot way for the torpedo guide-stud and forming a stop. This piston is held up by a spiral spring underneath it. To load the torpedo into the tube it is simply necessary to push it in until its guide-stud brings up against this stop, and then close and fasten the door. The clutch hole in the torpedo is then directly in line with the motor clutch, and the moment that these clutches are thrown in action, the torpedo is held firmly against all movement.
A long rod, W. W., performs the work of clutching, disconnecting and firing. The torpedo being in its tube, the powder charge may be inserted. Lift the small spring latch, X., open the breech, and insert the cartridge. It is to be remarked that unless the torpedo is clutched up ready for spinning, it is impossible to cock the hammer, and unless the torpedo is entirely free to leave the tube, it is impossible to fire. The action of firing itself is automatic and is controlled by the lever, O. By pulling back on the handle, Y., the long rod, W. IV., is drawn to the rear, clutching the motor to the torpedo, and bringing the lever, Q., into position, so that the movement of closing the little breech cocks the hammer. If the throttle valve be now opened, steam is given to the motor, and the fly-wheel will be spun up, it being possible to so set the regulator valve that the wheel will run at any desired speed of revolution.
Discharge is operated in the following manner: A small box, Z., contains an arrangement by which a small steam valve may be operated either electrically or by a firing laniard. The valve works instantaneously, and admits steam into the small pipe, a. a., communicating with the stop-pin. Steam coming on the upper side of this little piston forces it down so that the pin comes clear of the guide-stud on the torpedo, leaving it clear to leave the tube. As this piston descends, and after withdrawing the stop, a port is unmasked, admitting steam to the pipe, b. b. b., passing to the cylinder, T. T., whose piston is attached to the long rod, W. W., driving it forward. As the rod moves forward it first unclutches the motor, then cuts the steam off from the motor, and finally, at the end of its course, trips the hammer and fires the cartridge. Thus all the movements are performed automatically, and they can only occur in their proper succession. The entire time from pulling the firing laniard until the torpedo leaves its tube is but little over one second, most of this time being taken by the torpedo itself gathering movement.