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Basic Information

Originally a slang term for a naval mine, a torpedo, as currently understood, is a self propelled underwater projectile designed to deliver an explosive warhead to a maritime target. The name originates from the Latin torpere (to be sluggish or numb) and thus was given to the electric ray, on the basis of its paralyzing sting. Given that most encounters between humans and electric rays consist of the former stepping on the latter in shallow water and being stung, the analogy to a naval mine will be obvious. It was this type of weapon that Admiral Farragut was damning during his attack on Mobile Bay, much to the confusion of latter generations of American schoolchildren.

The next evolution was the spar torpedo - which was essentially a naval mine, on a pole, attached to the front of a small, relatively fast craft crewed by moderately suicidal men whose job was to ram the mine into the hull of an enemy warship. Even assuming that the warship's crew didn't veto this idea, the spar was never long enough to protect the attacking vessel and its crew (and arguably it never could be) and it was traditional for one or both to be lost (or at least damaged) in the attempt.

Given that the spar torpedo was not a popular weapon, there was some demand to develop a way to do without the spar and the attached boat and have the torpedo make its own way to the target. This was, however, easier said than done and it was not until 1868 that the engineer Robert Whitehead developed "the Whitehead secret" … a moderately reliable course and depth keeping device which allowed the torpedo as we know it today to be born. For some time thereafter "Whitehead" and "torpedo" were virtual synonyms (compare such brand names as "Hoover" and "Xerox").

Since that point they have been evolved tirelessly - fired from all sorts of platforms, with small boats and submarines being solid favourites, although they were cheerfully installed on larger craft as well, up to and including battleships, which should never normally get close enough to one another for successful torpedo attacks (the only known instance of a battleship torpedoing another battleship was when HMS Rodney used her torpedoes to sink KMS Bismarck - and at that stage the Bismarck was already crippled, ablaze and dying but, with most of her hits above the waterline, was proving slow to sink). From 1914 onwards, torpedoes were even deployed from aircraft (although in early iterations this involved landing a seaplane, pointing it at the target and letting the torpedo go - the in flight dropping of torpedoes followed a little later). Whitehead's first series produced weapons could travel about 1000 yards at about 6 knots - modern weapons can run at over 80 knots out to around 30 nautical miles, exact speed and range depending on the model and besides running straight, can be steered by wire and/or can home in on their targets using active and/or passive sonar. The homing torpedo has proved - theoretically at least - a popular anti-submarine weapon (in practice actual sinkings have been few and far between and the only time one submarine has sunk another with both submerged1 it was achieved with a well aimed spread of unguided torpedoes). Propulsion was initially by a clockwork driven propeller - all sorts of methods have been tried subsequently from electric motors and air-independent combustion engines to the alarmingly unstable binary propellants in some modern systems that can extract those 80 knot speeds from their pump-jet drives. (The "alarmingly unstable propellant" idea was pioneered by the WW2 era Japanese "Long Lance" torpedo which included a reserve of liquid oxygen to oxidise its engine fuel … cynical anecdote suggests that the aggressive torpedo tactics adopted by the IJN were at least partially inspired by the desire to get these things off their ships and heading towards the enemy before they were detonated by incoming fire … several Japanese warships were indeed lost to the detonation of their long-lances).

Torpedo warheads were initially impact fused - later investigation found that they could do a lot more damage by exploding under the keel of a target, but it took some time to make them do so reliably. Assuming reasonable proximity, the warhead in question is likely to consist of several hundred kilos of high explosive, its shock effect magnified by the surrounding water, and is a hit that few, if any, vessels can safely adsorb. Nuclear torpedoes were investigated, but generally found not to be worth the effort of deploying … and possibly a little too short ranged for safe use from a surface vessel, let alone a submarine.

Interestingly, torpedo building technology was also adapted by several users - notably the Italians - to create small, manned submersibles that could carry divers into the attack against enemy shipping. More aggressive versions where the diver acted as a guidance system for torpedo and its warhead were generally less successful due to the difficulty the diver had in safely abandoning the weapon during its attack run. Somewhat unsurprisingly the Japanese Empire was rather more sanguine about the prospect of what was effectively a suicide torpedo, and produced a number of Kaiten craft to fill the role … still with a marked lack of success. Sans suicidal urges, the descendants of the manned torpedo, now normally referred to as swimmer delivery vehicles are still pulling divers about to this day.


1. full source reference

Game and Story Use

  • Misfires with torpedoes are always fun - from the entry level (torpedo only partially leaves the tube), to the downright terrifying (torpedo circles round and comes back at the firer) with all manner of things in between. At the start of WW2 both the US and German navies were cursed with defective torpedoes - the German weapons were mainly troubled by defective magnetic influence exploders and would often detonate if they actually hit their target, the US ones were bad in so many ways that they were not only useless but effectively endangered the crews of US vessels.
  • The saner designs of manned torpedo make for pretty cool underwater transport - although in reality it was apparently a lot less fun than it sounds.
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