The Gyroscope.
From the foregoing description of the many devices employed to enable the Whitehead to accomplish the tasks for which it is intended, it might be thought that everything that science could imagine has been done to ensure its efficiency. There still, however, remained one great drawback to the efficiency of the torpedo, and this was its deflection from right to left, which was often so serious as to prevent it from striking the object at which it was aimed. The hydrostatic valve and the pendulum were sufficient to keep the torpedo at the required depth without diverging from her true vertical course, but it was apt to swerve from its course in a right or left direction either by reason of the blow it received on striking the water, by dents on its shell, by air leakage, or other causes. An error of only one degree in its course means a lateral error of nearly 50 feet at 800 yards, and it was in order to prevent the deflection of the Whitehead out of the line of fire that the principle of the gyroscope has been applied to the torpedo. In addition to her pair of ordinary vertical rudders, which may be set to any angle up to 20 degrees by means of a clamping screw, the torpedo carries a pair of movable vertical rudders placed in recesses in the vertical fins and controlled by the gyroscope through a servo-motor. The ordinary vertical rudders are usually discarded if the latter are carried.
Photos by] [West & Co.
THE FIRING OF A WHITEHEAD TORPEDO.
In a manifesto issued in July, 1901, the Navy League declared that owing to the lack of prevision no adequate provision for gyroscopes and other “essentials of efficient fighting” had been made. Soon afterwards, in the House of Commons, Mr. Arnold Forster, referring to the condition of the navy, remarked that the gyroscope was an exceedingly complicated and beautiful appliance, which from its nature and mechanism you could not get by sending round the corner. Its manufacture, he said, was a long process, involving considerable skilled labour, but still it had been carried out with unremitting zeal, and a great many vessels were supplied with them, He assured the House that there had been no relaxation in the effort to provide all torpedoes with this necessary and desirable accomplishment.
The working of the gyroscope as applied to the Whitehead torpedo may now be described. In the centre of the lower part of the buoyancy chamber is placed a small heavy-rimmed flywheel or gyroscope about 1¾ lbs. in weight, carefully suspended on gymbals (like a ship’s compass) in a vertical position and transverse to the axis of the torpedo. The apparatus is “set” by winding up a strong spring, and the action of firing the torpedo from the tube releases the spring and causes the gyroscope to spin round at a rate of about 2,200 revolutions a minute. The use of the gyroscope is based on the fact that if a wheel be set spinning on its axis with any considerable velocity, it will always tend to revolve in the same place to which it is set spinning. The gyroscope works a servo-motor, which in its turn works a pair of movable vertical rudders, and the slightest deviation from the direction in which the torpedo was originally fired causes the gyroscope to move the rudders and bring back the torpedo to its pre-determined course. Thanks to the hydrostatic valve, the pendulum, and the gyroscope, the Whitehead torpedo is almost certain to hit the object at which it is aimed. In peace manœuvres the Whitehead has often been run absolutely dead straight, with no divergence either up or down, or from right to left, to a distance of 2,000 yards. In 1890 the range of the Whitehead (Mark X R.L.) was officially placed at 800 yards, so the value of the gyroscope is quite evident.
Torpedoes are fired in four ways—
1. By submerged tubes. 2. By above-water tubes. 3. By revolving tubes. 4. By boat’s “dropping gear.”
The torpedo is blown out of the tube either by compressed air suddenly injected into the rear end, or by an impulse charge of a few ounces of powder, usually cordite. The air pressure varies from 300 to 600 lbs. to the square inch, and the powder charge from 4 oz. to 6½ oz. Submerged tubes are of course tubes below the water-line, and all the most recent ships are fitted with these, as their advantages over above-water tubes are universally recognised. After the Chino-Japanese war all governments, when demanding designs for new warships, made it almost a sine qua non that the torpedoes should be discharged from below water. In firing torpedoes from above-water tubes the torpedo is liable to be hit by the enemy, and it is generally considered that if the tube be hit by even a small projectile it must inevitably explode; the submerged tube affords protection both to the men and the weapon, while the torpedo is less deflected on entering the water. The weight of the submerged tube is some 7 tons, 2 tons more than an above-water one. In order to avoid any possibility of the Whitehead inflicting injury on the vessel firing it, and in order that it may be as little deflected as possible, a guiding bar is run out of the tube by means of pneumatic power when the torpedo has been placed in it. The guiding bar holds and guides the torpedo until quite clear of the ship, when by means of a secret apparatus it releases the torpedo at the end simultaneously; without this arrangement the torpedo would be enormously deflected towards the stern directly it began to leave the tube, and would probably strike the ship from which it had just been fired.
Revolving tubes are carried either singly or in pairs on board torpedo-boats and destroyers, and the torpedoes are fired from them by powder impulse only. “Dropping gear” is only used on second-class torpedo boats and picket boats. It consists of a pair of clip tongs suspended from pivoted davits; the tongs being opened, the torpedo falls into the water, the engines are set in motion, and it speeds off to do its deadly work. The torpedoes for the English Admiralty are made at the Royal Gun Factory, by Messrs. Greenwood and Batley, of Leeds, and by Mr. Whitehead’s factory at Portland.