The "Long Lance" Torpedo
It was perhaps the best torpedo of the war. What made
it so good? Several things made the oxygen type "Long Lance" torpedo "so
Size: while the difference between a 21" and a 24" torpedo in diameter is not
that much, the warhead on the larger one varies by the ol' "pi" ratio. The
Japanese warhead was also longer in relative terms, making for a much more deadly load on
Simplicity: The development of the Japanese oxygen torpedo started in earnest back in the
1920's, and it was a "mature" weapon by the 1940's. Other nations tried to
produce them as well (England and France, for example), but gave up as they felt the
hazard was not worth the benefits. The Japanese continued in their efforts, and partially
succeeded. The IJN also did not flirt with the magnetic exploder as did the US, Germany
and Great Britain.
Speed: Oxygen torpedoes have two benefits: lack of
combustion byproducts that leave a wake (most notably nitrogen; air torpedoes have less
oxidizer (oxygen) and more inert gasses (nitrogen primarily) in their air flasks), and
range (pure oxygen takes up less space than the same amount of oxygen as a component of
air (tops of 20% by volume); more space for fuel and oxidizer. Oxygen oxidized flames also
burn hotter (better combustion), so a given amount of fuel could stretch farther. All this
translated out into going further faster.
I don't have the figures with me, but I think that the top speed on our torpedoes (which
only allowed a very short range) was well below the lower speed on the Japanese torpedo
(which allowed a range that was so great we had trouble believing that it actually could
occur). At their top speed, the things zipped along near 50 knots (compared to a top ship
speed of 37 knots or so) out to a distance that was greater than our "close
range". Faster to the target means less time to evade, hence more accurate. Longer
range meant that we found ourselves surprised by Japanese torpedo attacks on at least
three occasions, thinking that we ran over mines as there was no way that the nearest
Japanese forces could have torpedoed us. We were, of course, wrong. The sinking of the
USS Wasp, damage to the USS North Carolina, and fatal damage to a destroyer (don't recall
the name; USS Edsall perhaps?) all by _one_ torpedo salvo from a single Japanese
submarine, remains the greatest monument to Japanese torpedo systems (and to the American
refusal to believe that someone else could do something better than us).
Skads of them: Japanese ships were heavy on torpedo
tubes, and even heavier on reloads. Some Japanese destroyers could reload twice, and could
complete the reload cycle in twenty minutes or so. This tends to put more torpedoes in the
water, increasing the likelihood of hits
Systems: The Japanese put a lot of effort into their torpedo warfare, much
moreso than the rest of the world. They saw the torpedo as an equalizer for the
inferiority of size that they were persuaded to accept as part of the naval treaties
entered into post WWI. They integrated the torpedo attack at both the destroyer and the
cruiser levels (whereas most other nations made the destroyer use a "second
function" and pretty well ignored the cruiser level (although some early US cruisers
had tubes, they were almost completely abandoned by World War II (and for some pretty good
reasons, see below). Torpedo directors were a major part of surface ship fire control
systems, not a addon as found elsewhere.
Skills: They practiced their doctrine, firing real torpedoes all the
while, and not in the fairy tale conditions of the Caribbean Sea, either.
Japanese training was intensive, brutal (the North Pacific during the winter is not a
tranquil place) and all encompassing. Unlike shells, torpedoes could be fired and
recovered to fire again in a training situation. The IJN had a whole class of torpedo
support craft (covered in post war intelligence reports by the USN, by the way).
Stupidity (American): A lot of the IJN's success was due to the USN fighting a war that
fit the IJN's doctrine. Early on, we persisted in using radar like it was eyesight,
maneuvering in formations that suited the Japanese proclivity for torpedo attacks, and
misusing one of the American "secret weapons" (the automatic loading 6"
light cruiser) to almost a criminal extent. Once we got things sorted out, we did a lot
better. The Japanese did a lot of stupid things too; somewhere in 1943 or thereabouts both
sides straightened themselves out and the good aspects of both navies produced some
interesting surface combats. At that point, the torpedo was nowhere near as dominant as it
was when we were feeling our way early on.
In short, there were a number of factors that combined to make the Japanese torpedo threat
so effective during World War II. The torpedoes themselves were only one of many such
factors that made it a success (from the Japanese point of view, of course).
The "all torpedo approach" to light forces has its disadvantages. One is time on
target for the weapons system; the torpedo can be avoided while the 6" shell cannot.
Another is the massive concentration of explosives outside of the warship's protective
systems. This is why the US gave up on torpedoes on cruisers. The Japanese lost one ship
(don't remember which one) when the torpedoes were touched off by otherwise minor gunnery
damage, and they did jettison torpedoes on more than one occasion when this was
threatened. Torpedoes are also expensive compared to main gun rounds, even when you
compare the number of the shells that have to be fired to get the same effect.
One more thing: not all Japanese torpedoes were of the "Long Lance" variety.
They also had 21" torpedoes on many of their submarines and some older surface
ships. All of their torpedoes were well made (albeit mostly hand fabricated) and
functioned well, according to post war tests by the Naval Intelligence Mission to Japan.
The report (available on cheap microfilm from the Naval History Center in Washington DC)
will tell you more than you ever want to know about the subject...
Author: PDC Sensha
Used by Permission