Propulsion

D	Dampftorpedo (wet heater, World War I)
a	Air/steam (wet heater, World War II)
e	Electric
u	Hydrogen peroxide

Diameter

F	45 cm
G	50 or 53.3 cm
H	60 cm
J	70 cm
M	75 cm

German Torpedos manufactured prior to the end of World War II were designated as to their diameter, length and propulsion. Modifications were usually, but not always, denoted by T numbers. Length was to the nearest meter. For example, the designation G7e T2 meant that the torpedo was 53.3 cm (21") in diameter, was about 7 meters long, had an electric motor and was the second modification to the original design.

The outfit for U-Boats was at least four electric torpedoes for every wet-heater while surface ships used only wet-heaters. Schnellbootes (E-boats) used primarily wet-heaters, although electrics were also issued.

Italian torpedoes used by the Germans were denoted by the manufacturer, w for Whitehead (Fiume) and i for Silurificio Italiano (Naples).

During World War II, over sixty different torpedo designs were tested, 16 using hydrogen peroxide as an oxidant. Monthly production rose from 70 before the war to 1,000 by the spring of 1941, to a peak of 1,700 in 1943 and then fell to 1,400 during 1944. Total production of 53.3 cm (21") torpedoes was about 70,000. However, not counting those expended for testing, destroyed in bombed depots or lost in sunken ships, wartime expenditures were just over 10,000 of which about 7,000 were electric G7e, 2,300 wet-heater G7a and 640 electric acoustic homing T5 (Zaunkönig 1). Manufacturing took place at Deutsche Weke Kiel, Julius Pintsche Berlin, Auto-Union Zwickau, Borgward Bremen and Planeta Dresden.

German torpedoes designed after World War II are named after sea animals.

Most German torpedoes designed before 1906 used three-cylinder radial engines based upon the Brotherhood system, which used compressed air as a power source. Later versions used a Brotherhood four-cylinder central crank engine which had increased power.

After 1906, German designs used wet-heater motors. These pre-heated the air being fed into the engine, significantly increasing the range of the torpedo.

As noted above, during World War II submarines generally carried electric motor torpedoes, as these made little noise and were essentially wakeless. Surface ships did not use these as it was felt that the shock of the torpedo hitting the water would rupture the batteries. Instead, surface ships used wet-heater engines notable for using Decalin (decahydronaphthalene) instead of kerosene for fuel. Much research was performed upon hydrogen peroxide fuels during World War II, but no torpedo using this fuel ever entered service.

Post-war designs rely upon silver-zinc batteries for power.