G7e torpedo

The G7e torpedo was the standard electric torpedo used by the German Kriegsmarine submarines in World War II. It came in 20 different versions, with the initial model G7e(TII) in service at the outbreak of the war. Due to several problems, leading to the German "Torpedokrise" which lasted until the end of 1941, the improved G7e(TIII) took over as the standard electric torpedo used by German U-boats for the rest of the war. G7e torpedoes measured in diameter and about in length. Depending on the type, the warhead contained a main charge of of Schießwolle 36, a mixture of dipicrylamine and TNT. All were powered by electric motors and lead-acid batteries which required onboard maintenance to maintain their functionality. Other major G7e-versions that saw operational service during the war, were the first acoustic homing torpedo G7es(TIV) Falke and its improved successor G7es(TV) Zaunkönig. The G7e(TII) went in service with German U-boat fleets in 1936. Its existence was virtually unknown to the British until fragments of one torpedo were recovered following the sinking of the Royal Oak in October 1939. The advantages of the G7e in contrast to the G7a wet-heater steam-driven torpedo rested in its simplicity and cheapness of manufacture (half the cost), as well as being virtually silent and leaving almost no visible trail of air bubbles to alert ships that they were under attack. However, in all other respects, the TII was less reliable and performed unpredictably compared to the G7a(TI), with shorter range of and slower speed at . Additionally, the batteries of these torpedoes needed to be preheated to a temperature of to operate with maximum speed and range, though generally this was not a problem since U-boats had the element of surprise and often had the advantage of firing the first shot. Poor range and speed were not the TII's only problems. Both the contact and magnetic detonators were unreliable, major flaws that also afflicted the United States Navy's standard Mark 14 anti-submarine and anti-ship torpedo.