Harper's Round Table, February 16, 1897

by Various

A WHITEHEAD TORPEDO.

The Whitehead torpedo consists of several well-defined parts. The first is the head, where the guncotton is placed for explosion. This part is what is called "ogival" in shape, and is bluntly rounded. Then comes quite a long straight part. That is the chamber for the compressed air. Then there is what is called a buoyancy chamber, in which is placed the diving apparatus. Then follows the engine-room, to which the water is admitted through little slits in the torpedo. Then comes another buoyancy chamber, in which the important parts of the steering apparatus are placed, and then comes the tail with its two screws and rudders and fins.

The war-heads of the torpedoes of the largest size contain 220 pounds of guncotton. Most of this guncotton is kept in a damp condition. The rest is dry. The dry guncotton is exploded by a small charge of fulminate of mercury, and that in turn explodes the wet guncotton. About the only thing that will explode wet guncotton is dry guncotton. The war-heads of the torpedoes are so arranged that until they travel at least eighty yards from a ship the firing apparatus is locked. This saves the ship from being destroyed by its own weapon in case of accident. When the nose of the war-head strikes an object, it pushes a pin through a copper partition into the fulminate of mercury, and the explosion follows.

The torpedo's air-chamber consists of forged steel about an inch thick. It must be very strong, for it must be charged with compressed air to a pressure of 1350 pounds to the square inch. Expensive machinery is used in finishing off this part of the torpedo. The lathes, that work on the inside can produce steel shavings of the thickness of a thousandth of an inch. The long after-part of the torpedo is made of thin steel, but strongly braced so that the machinery can do its work.

We probably can best understand how these little ships are made by studying what they do. Suppose the battle-ship Kentucky wants to sink an antagonist in war. The air-compressor is set at work. A large-size torpedo is swung on a rack and lowered to a tube in the side of the ship, and slid in place. A valve is attached to an opening in the torpedo, and the air is compressed into the air-chamber. By means of a measuring device the observer has fixed the exact time and direction when to discharge the torpedo so as to hit the enemy. Four ounces of powder have been inserted in the torpedo-tube back of the torpedo, and the word to fire is given.

By a simple arrangement the air-valves are closed, the machinery in the torpedo unlocked so that after it strikes the water the air will flow into the engine and start the screws going. The gauges and springs have also been so arranged that the torpedo will remain at a fixed depth. With a speed of about a mile in two minutes the 16-foot torpedo rushes through the water. If it strikes the enemy, a great naval catastrophe happens. If it misses, it is so arranged as to sink after it has spent its force, and to disappear out of the way of doing harm to shipping. If practice work is being done with the torpedo at any time, the mechanism is so arranged beforehand that when the torpedo has run its course it rises to the surface and is recovered.

How does a torpedo keep at a certain distance under water? Well, there are two bits of machinery to accomplish that. One is a pendulum. If the nose of the torpedo raises itself, the pendulum swings backward and depresses the rudders at the stern, and brings down the nose. If the torpedo begins to dive, the pendulum moves forward, and the opposite result follows. The torpedo remains at the required depth through the pressure of the water that comes into the engine-room on a rubber diaphragm, to which is attached a delicate spring. The pressure of the water and the strength of the spring offset each other when the torpedo is at the depth wanted. If the torpedo sinks or rises, the harmony between the spring and the pressure of water is disturbed and the steering-engine is affected, and the rudders moved so as to keep the weapon at a certain depth. Slight changes up or down are regulated by this machinery; but if the plunge or rise is of a serious nature, the pendulum begins to swing, and the torpedo corrects its course at once.

Another most delicate part of the torpedo's machinery is what is called a "valve group." This is a set of valves used for various purposes, the chief of which is to restrain violent action from the compressed air during changes in direction of the little craft or during its run. They have such names as the "controlling valve," the "reducing valve," the "regulating valve." The flow of air into the little three-cylinder engine must be constant and of a certain pressure. The screws at the stern of the boat must be turned at the rate of about one thousand revolutions a minute, and the control of the force that propels them must be most efficient.

Another piece of important machinery is known as the "locking gear." When a torpedo is shot into the water from a ship the pendulum may lag a little in its swing forward. This would put the rudder down and make the torpedo take a deep dive. In shallow water this might mean contact with the bottom, and of course that would never do. The locking gear prevents any action by the rudder until the torpedo has travelled about a hundred yards. By that time the craft has settled to its work, and has ceased to make any skipping motions in the water. Thus we see that the torpedo is not ready for full duty until it has gone a considerable distance from the ship. It cannot explode nor steer itself until it is darting through the water under its own power at a certain depth and at a certain speed. If it does the work expected of it, it will strike its target in probably less than one minute. It therefore does appalling destruction in almost an instant.