Engineering Wonders of the World
Volume I

436 ENGINEERING WONDERS 01' THE WORLD. FIRING A TORPEDO FROM A DESTROYER. THE MISSILE NOT YET CLEAR OF. THE TUBE. {Photo, Gale and Polden.) small auxiliary air engine entirely distinct from the main machinery actuating the pro- pellers, and which is to a torpedo what the steam steering gear is to a ship. A half-ounce pull on the rod operated by the disc and pen- dulum is transmitted as a pull of 180 lbs. by the servo-motor to the horizontal rudders. Behind the balance chamber is (4) the engine- room. This contains the propeller engines, servo-motor, and counter-gear for making range adjustments. The engines are of a type mostly constructed by Messrs. Brother- hood, develop 56 horse-power, and have three cylinders set at angles of 1203 round a central shaft driving the rear propeller. Bevel-wheel gearing turns in the reverse direction a sleeve to which is attached the forward propeller. Next in order comes (5) the buoyancy chamber. This small chamber contains the gyroscope, and provides the buoyancy of the torpedo. With the air chamber charged to a pressure of 2,250 lbs. to the square inch, and a dead weight of nearly 200 lbs. in the war-head, the buoyancy of a tor- pedo is a negative quantity. It is necessary in peace time that the torpedo should be recoverable after firing, and the expenditure of air during the run reduces weight suffi- ciently to ensure the projectile floating on the surface. But in war time the torpedo would be set to sink should it miss its mark, for it would be dangerous to allow so potent a weapon to float about the open sea when once the safety-pin has been removed from its live head. The torpedo’s gyroscope, the prin- ciple of which is the same as that of the cheap toy sold under that name, weighs 15 lbs. in all, and its central feature, the wheel, weighs 1| lbs. This gyroscope is carefully suspended on gimbals in a vertical position and transverse to the axis of the torpedo. Attached to its own axis is a powerful steel spring connected with a toothed gearing, actuated by a rod attached to the air lever that starts the main engine. The effect of throwing back the air lever is to release sud- denly the spring, which has previously been compressed by hand, with the result that the gyroscope is spun round at an enormous ve- locity—about 2,200 revolutions a minute. The gyroscope works a servo-motor actuating a pair of movable vertical rudders. If now the torpedo, from any cause, be deflected out of the line of fire, the gyroscope, by maintaining its axial position in the line of fire, acts on the servo-motor, and, by means of the ver- tical rudder, steers the torpedo back again to its original direction. The cost of each gyro- scope, including the royalties attaching to its manufacture, is £50, no inconsiderable propor- tion of the value of a complete torpedo. TORPEDO CLEARING ITS TUBE. {Photo, S. Cribb.)