An elementary treatment of the theory of spinning tops and gyroscopic motion, by Harold Crabtree.

CHAPTER V.

PRACTICAL APPLICATIONS.
I. THE STEERING OF A TORPEDO.
68. An allusion has already been made on p. 29 to the
gyroscopic mechanism employed for automatically steering a
torpedo. The patent was originally protected by M. Obry, an
Austrian engineer, and sold to the authorities of the Whitehead
Torpedo Works at Fliume, by whom it was improved and
finally patented in its present form in 1898. The following
is a brief outline of the way in which the steering is effected.
As the torpedo passes through the impulse tube, a trigger
projecting from its upper surface catches against a bolt in the
tube and releases a spring by which the gyroscope is spun
(see p. 29). Thus, before the torpedo enters the water, the
axle of the gyroscope is pointing in the required direction,
from which it never deviates (p. 11). Any deviation sideways
on the part of the torpedo only alters the position of the
gyroscope relatively to the torpedo. The gyroscope is fitted
to the torpedo in such a way that this relative change of
position opens one of two valves (the other being temporarily
closed) connected with the compressed air chamber from which
the screws of the torpedo are driven.
The air rushing through either valve drives (in one case
forwards and in the other backwards) a piston rod connected
with a vertical rudder at the stern of the torpedo, and the
valves are so arranged that when the torpedo swerves to starboard the rudder steers to port, and vice veirsa. The middle
position when both valves are closed is scarcely ever maintained
for an appreciable time, with the result that though the torpedo
maintains the direction intended it is by means of a zig-zag
path, roughly 2 ft. broad.
The mechanism is in addition so arranged that if the position
of the object fired at prevents the torpedo being aimed directly
at it, it is possible to set the gyroscope (apart from the torpedo)
in such a direction that the latter will eventually strike the
object, although in the first instance not aimed directly at it.
Full particulars and diagrams of the invention can be procured at the Patent Office, Southampton Buildings, London.