THE SUBMARINE TORPEDO
The submarine torpedo has become one of the principal naval arms. Not
only does it supply the chief offensive power of the submarine, the
torpedo-boat and the destroyer, but it is also carried as a separate
arm, with a special highly-trained crew, by almost every warship afloat.
At the beginning of hostilities the Naval Powers engaged owned
considerably over 80,000 of these weapons, and _one_ factory in England
alone can make them at the rate of two a day. During the first few weeks
of the _Great War_ the torpedo was responsible for the sinking of
warships to the value of over one million sterling. Had the German Fleet
been on the high seas instead of in harbour and protected from torpedo
raids by carefully-prepared submarine defences, there is little doubt
but what several more of the enemy’s ships would have been sunk by this
weapon. The fact that at first the British light cruisers suffered
rather heavily—though in total loss of ships and men less than the
German Navy—does not point to any advantage derived either from the type
of torpedo used or from skill in this mode of warfare possessed by the
Germans, but clearly to the timidity of the German main fleet, which was
at the very beginning of hostilities withdrawn from the zone of war and
placed behind fortifications, where it was safe from torpedo attack. The
British Fleet, true to the policy of “attack and not defence,” began
operations the moment war was declared, with results so brilliantly
successful, and of such far-reaching and world-wide importance, that
enumeration is well-nigh impossible. But while all these operations were
in progress the British Fleet was more or less exposed to torpedo attack
by any hostile submarines or fast surface craft which might succeed in
getting past the cordon of protecting destroyers, while the German Fleet
was safe, but ignominiously impotent. That the naval losses of Great
Britain, with all her fleets at sea, have not been far greater than they
have is in itself a victory of the greatest magnitude—a victory due
entirely to consummate naval skill.
The modern torpedo varies in length from 14 to 19 feet, and weighs up to
half a ton. It has an extreme range of 4,000 yards, or just over 2 ¼
miles. There are three types of torpedoes in use by the fleets at war.
The British use the _Whitehead Torpedo_, the French the Whitehead and
the _Schneider_, the Russians and the Japanese use the Whitehead; the
Germans have a type of their own, known as the _Schwartzkopf_, and the
Austrian arm is principally the Whitehead. All these types are alike in
their essential features, and therefore need not be described
separately.
The latest pattern 18-inch Whitehead torpedo is propelled by compressed
air stored in that section of the weapon known as the _air-chamber_ (see
diagram). The air on being released is heated and expanded in a tiny
three or four-cylinder engine which operates twin screws, moving
“clockwise” and “anti-clockwise.” The “war-head” contains about 200
pounds of wet gun-cotton which is exploded on the torpedo striking an
object. The essential features of the Whitehead torpedo are shown in the
diagram.[9]
This torpedo maintains a speed of 42 knots for 1,000 yards, 38 knots for
2,000 yards, 32 knots for 3,000 yards, and 28 knots for 4,000 yards.
Thus, if discharged at a distance of half a mile it reaches its object
in about 45 seconds.
[Illustration:
Sketch showing the essential parts of a Whitehead torpedo. _A._ Pistol,
detonator, primer, which causes the explosion of “B” when the torpedo
strikes an object. _B._ Explosive head, filled with wet gun-cotton.
(The “war-head” is substituted by a weighty dummy during practice.)
_C._ Air chamber with compressed air, at a pressure of approximately
1350 lbs. per square inch, for action. The chamber is tested to stand a
pressure of 1700 lbs. per square inch. _D._ Balance chamber, containing
mechanism for regulating the depth of submergence at which the torpedo
is adjusted to run. _E._ Engine-room, containing propelling machinery
(I.H.P. 60 in latest 18-in. type). _F._ Buoyancy chamber—a practically
empty chamber—to give the necessary buoyancy to the torpedo. _G._
Gyroscope. An instrument for correcting any deviation of the torpedo
from the line of fire. _H._ Rudders, and mechanism for operating. _I._
Twin-screws, operating “clockwise” and “anti-clockwise.”
]
Torpedoes are fired—or ejected—into the sea from surface or submerged
tubes, and on striking the water are propelled by their own engines in
an absolutely straight course towards the target. The exact mechanism of
the submerged tube—which is used in surface warships as well as in
submarines—is a naval secret. When fired from a surface tube the torpedo
sinks immediately to a depth of about 10 to 14 feet, and maintains this
depth until it strikes its object. When fired from a submerged tube it
rises—if necessary—to the same level. A torpedo always proceeds towards
its object of attack at a depth of a few feet below the surface. This,
combined with speed, renders it almost impossible to destroy an
approaching torpedo by gun-fire. So marvellous is the mechanism of these
little weapons that in anything like favourable circumstances they may
be _depended upon_, if well aimed, to strike within a yard or two of the
spot aimed at. This accuracy is due almost entirely to the gyroscope,
which, briefly described, is a rotating wheel automatically controlling
the torpedo’s course.
Although for many years torpedoes have been carried by nearly all types
of service warships, none of them were really ideal for this kind of
warfare. A new field for the torpedo was, however, opened out by the
introduction of the submarine boat. In order to be effective the torpedo
must be discharged from a distance under 4,000 yards—preferably from a
point less than half this distance from the object of attack. This means
that the vessel carrying the torpedo would have to get within a mile, or
at least a mile and a-half, of her object of attack before discharging a
torpedo. For a surface vessel to accomplish this in the face of a heavy
cannonade from quick-firing guns would be extremely risky. To make a
quick rush to close quarters, if possible, by several vessels from
different points, was the only chance of delivering a successful torpedo
attack on a hostile warship; unless, of course, she was favoured by fog
or darkness _at the right moment_—favourable conditions which would
seldom obtain in actual warfare. Again, every increase in the speed of
the big surface warship rendered the task of the ordinary torpedo-boat
and destroyer more difficult because in the event of a threatened attack
the larger vessel would make use of her speed to keep out of torpedo
range while her powerful guns were repelling the attacking torpedo-boat.
The _hour_ of the torpedo came with the _perfection_ of the
submarine. All the conditions of an ideal torpedo-boat were
fulfilled—_invisibility_ rendering daylight attacks possible;
_almost perfect immunity from gun-fire_ enabling the torpedo to be
discharged at closer range; _submerged discharge_ removing the
likelihood of the weapon being exploded by accurate gun-fire before
being discharged; _speed on the surface_ enabling the “carrying”
vessel to manœuvre for position; _moderate speed when submerged_
enabling an attack under all reasonably tactical conditions; and
_comparatively large displacement_ giving good cruising qualities,
wide range of action, and enabling a large number of torpedoes and
tubes being carried.
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Footnote 9:
“Submarines of the World’s Navies,” By Charles W. Domville-Fife.
(London: Francis Griffiths.)