Figure 10-2.-Depth-setting dial.
into the detonator. The booster, already in position, then
fires and, in turn, sets off the entire load of TNT.
These two bellowsoperated by hydrostatic
pressureserve two purposes. First, they permit the
depth charge to fire at the proper depth; second, they
make the charge safe to handle and carry. If you should
accidentally knock the safety fork and the valve inlet
cover off on deck, nothing would happen. Even if the
detonator should go off while you were handling the
charge, the main charge would not fire unless the booster
was in the extended position.
To keep a torpedo on course toward its target is a
job. Maintaining the proper compass course with a
gyroscope is only part of the problem. The torpedo must
travel at the proper depth so that it will neither pass under
the target ship nor hop out of the water on the way.
As figure 10-3 shows, the torpedo contains an
air-filled chamber sealed with a thin, flexible metal
plate, or diaphragm. This diaphragm can bend upward
or downward against the spring. You determine the
spring tension by setting the depth-adjusting knob.
Suppose the torpedo starts to dive below the
selected depth. The water, which enters the torpedo and
surrounds the chamber, exerts an increased pressure on
the diaphragm and causes it to bend down. If you follow
the lever system, you
push forward. Notice
can see that the pendulum will
that a valve rod connects the
Figure 10-3.-Inside a torpedo.
pendulum to the piston of the depth engine. As the piston
moves to the left, low-pressure air from the torpedos air
supply enters the depth engine to the right of the piston
and pushes it to the left. You must use a depth engine
because the diaphragm is not strong enough to move the
The piston of the depth engine connects to the
horizontal rudders as shown. When the piston moves to
the left, the rudder turns upward and the torpedo begins
to rise to the proper depth. If the nose goes up, the
pendulum swings backward and keeps the rudder from
elevating the torpedo too rapidly. As long as the torpedo
runs at the selected depth, the pressure on the chamber
remains constant and the rudders do not change from
their horizontal position.
Navy divers have a practical, first-hand knowledge
of hydrostatic pressure. Think what happens to divers
who go down 100 feet to work on a salvage job. The
pressure on them at that depth is 8,524 pounds per
square foot! Something must be done about that, or they
would be flatter than a pancake.
To counterbalance this external pressure, a diver
wears a rubber suit. A shipboard compressor then pumps
pressurized air into the suit, which inflates it and
provides oxygen to the divers body as well. The oxygen
enters the divers lungs and bloodstream, which carries
it to every part of the body. In that way the divers
internal pressure is equal to the hydrostatic pressure.
As the diver goes deeper, the air pressure increases
to meet that of the water. In coming up, the pressure on
the air is gradually reduced. If brought up too rapidly,
the diver gets the bends. That is, the air that was
dissolved in the blood begins to come out of solution