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A Torpedo during the dreadnought era is an underwater missile that propels itself toward a target vessel in the water where it will detonate to cause ruinous damage by loss of buoyancy to the target.

The word used to mean what in the dreadnought era was called a mine: an explosive charge triggered by some means when a ship was nearby, or a charge thrust toward an enemy ship on a spar. For a period in the 1870s to early 1890s[Citation needed], the introduction of modern torpedoes caused the bifurcation to "torpedoes" and "automobile torpedoes". By the time of The Great War, the potential of modern torpedoes was so fully realised that they were being called "torpedoes", and the old variety of weapon was dubbed "mines". This is the terminology that we will use throughout this site unless we are trying to allude to the pre-historical period or are quoting others.

Development of the Modern Torpedo

There were a few precursor efforts at motive torpedoes, including precocious efforts at remote guidance and the simple resort to a surface-swimming vessel packed with explosives. The benefits to having a torpedo swim under the water to its target were seductive, however, and prompted odd variations such as torpedoes swimming on tethers beneath small pontoons.

Efforts at a developing torpedo that would swim at a fixed depth toward an enemy were confounded until Robert Whitehead recognized that the "porpoising" motion exhibited by previous efforts at simply binding a diaphragm manometer to a control surface could be overcome by factoring in a measure of the torpedo's current pitch angle in the water (which, for small angles, was proportional to the derivative of depth). Once he had created a mechanisms that could combine these two values in a weighted fashion, he found that reliable and stable depth-keeping resulted. This was an early demonstration of theory. He started manufacturing torpedoes in Fiume with a firm named Schwartzkopf and licensing the principle to the Royal Navy and other parties to do the same. This was an innovation so fundamental that it was dubbed "The Secret", and licensees swore to safeguard it.

His success was such that for a fair time before 1910, any workable torpedo pretty much had to have his patent at its heart, and they were sometimes called "Whitehead torpedoes".


Torpedoes were for a time simply tuned carefully (by tweaking a vertical rudder after repeated test firings) so they would run "straight enough". When this proved insufficient, a gyroscope was introduced to the design to provide a reference to guide an articulated vertical rudder to steer it on an unwavering course along the line it was fired.

The ability to set a torpedo to run on a heading other than the one it entered the water on was slowly adopted in fits and starts as the war progressed. As most torpedo tubes made any physical interface (to express a turn desired after firing) difficult, the practical use of "steerable" torpedoes was largely theoretical as torpedoes had to have a knob on their circumference turned to express this angle and it could only be done before they we placed back into their tube.

In essence during the dreadnought era, gyroscopes only helped a torpedo steer a straight course and to correct any transient change in heading they sustained as they entered the water; they did not fundamentally alter their firing angle until late in the war and from tubes that had been specially designed.

Heater Torpedoes

I know crap-all about torpedo motors, but most of them ran on compressed air. It was discovered around 1905 that by heating this air as it bled out from its charging chamber greatly improved the endurance of torpedoes. This permitted the new "heater" designs to reach longer ranges at any given speed or to have higher speeds.


This is the part that went bang. Someone who knows something will write in here about the various compositions used, and their various weights, etc.

Net Cutters and Recorders

[TO BE CONTINUED - TONE] write about netting and methods of defeating it. Roll and depth recorders. Many docs in ARTS.

Minor Variants

Howell torpedoes ran on a motive force supplied by a massive flywheel set spinning angrily within their chassis. This American design had a fair range for its day and the added gyroscopic stability provided by its flywheel's rotational inertia was a plus, as well.

Basic Operation in the Era

Setting the Speed

Most torpedoes used in the Great War had two or more modes they could run in which offered different trade-offs in the endurance/speed envelope. For instance, by tweaking a little sliding member on the periphery of a torpedo, it might be set to "high speed" or "extended range" (E.R.) mode. E.R. would run at a lower speed, but often to a vastly greater range.

Setting the Run-Depth

Most torpedoes also had a means to tune the depth they would seek and try to maintain as they ran. This was probably done quite similarly to setting their speed.[Citation needed]


Through the middle of the war, the British generally relied upon devices called torpedo directors to aim their torpedoes. Directors generally combined the task of calculating the angle between line of sight and line of torpedo at the moment of firing with the means of sighting along it to judge when to fire the torpedo.


Prior to 1912, bubbles from heater torpedoes were calculated to rise at 1.8 feet per second. This was found to be a rough characterisation; British experiments at Portland determined the following times:[1]

  • a depth of 8 feet = 4.5 seconds
  • 12 feet = 6.6 seconds
  • 16 feet = 7.6 seconds
  • 20 feet = 9.6 seconds

See Also


  1. Annual Report of the Torpedo School, 1912. p. 24.