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The G7e torpedo was the standard electric torpedo used by the German ''
Kriegsmarine The (, ) was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official military branch, branche ...
'' submarines in
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. 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-boat U-boats are Submarine#Military, naval submarines operated by Germany, including during the World War I, First and Second World Wars. The term is an Anglicization#Loanwords, anglicized form of the German word , a shortening of (), though the G ...
s 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 Hexanitrodiphenylamine (abbreviated HND), is an explosive chemical compound with the formula C12H5N7O12. Since it is made from readily available raw materials, HND was used extensively by the Japanese and less extensively by Nazi Germany during W ...
and
TNT Troponin T (shortened TnT or TropT) is a part of the troponin complex, which are proteins integral to the contraction of skeletal and heart muscles. They are expressed in skeletal and cardiac myocytes. Troponin T binds to tropomyosin and helps ...
. 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''.


G7e(TII)

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 in October 1939. The advantages of the G7e in contrast to the
G7a The G7a(TI) was the standard issue ''Kriegsmarine'' torpedo introduced to service in 1934. It was a steam-powered design, using a wet heater engine burning decaline, with a range of at speed. In 1936, the Kriegsmarine's first electrical power ...
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. The magnetic influence exploder, designed to allow the torpedo to run under the keel of a ship and detonate, breaking the ship's back, was inconsistent and would often detonate prematurely, or not at all. This led the
BdU The ''Befehlshaber der Unterseeboote'' or BdU (Eng: "Commander of the U-boats") was the supreme commander of the German Navy's U-boat Arm (''Ubootwaffe'') during the First World War, First and Second World Wars. The term also referred to the Comm ...
to order that all G7e(TII) torpedoes be fired only for contact detonation. However, the contact pistol of the TII also proved to be unreliable; the British
battleship A battleship is a large, heavily naval armour, armored warship with a main battery consisting of large naval gun, guns, designed to serve as a capital ship. From their advent in the late 1880s, battleships were among the largest and most form ...
managed to survive almost certain destruction when three torpedoes from struck on her keel, two broke upon hitting and the other failed to explode. These technical defects led to the circumstance that attacks on at least one battleship, seven
heavy cruiser A heavy cruiser was a type of cruiser, a naval warship designed for long range and high speed, armed generally with naval guns of roughly 203 mm (8 inches) in calibre, whose design parameters were dictated by the Washington Naval Treat ...
s, seven
destroyer In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escort larger vessels in a fleet, convoy, or carrier battle group and defend them against a wide range of general threats. They were conceived i ...
s and some
cargo ship A cargo ship or freighter is a merchant ship that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's List of seas, seas and Ocean, oceans each year, handling the bulk of international trade. ...
s were not successful. Nevertheless, the German Navy, after much prodding by German U-boat Command (
BdU The ''Befehlshaber der Unterseeboote'' or BdU (Eng: "Commander of the U-boats") was the supreme commander of the German Navy's U-boat Arm (''Ubootwaffe'') during the First World War, First and Second World Wars. The term also referred to the Comm ...
), invested resources into correcting the TII's flaws. Gradually, it improved, and by the end of the Norwegian Campaign problems with the contact exploder and depth-keeping gear had been mostly solved, with significant strides made in improving the magnetic proximity feature. At the same time, the TII's range was increased from . By that time, however, the TII was already being phased out of production.


G7e(TIII)

Improvements in the design of the G7e(TII) were incorporated into the production of the next model of electric torpedo for Germany's U-boat fleet. Introduced in 1942, the TIII represented a vast improvement over the early TII. The faulty exploders from the TII were scrapped in favor of a new design. The TIII had a range of and could achieve . With the improved design the TIII complemented the G7a(TI) wet-heater torpedo, which was only used at night for the rest of the war (it remained the only torpedo used by surface ships though), and the TIII was used for day-attacks. Using the TIII's perfected proximity feature, U-boat captains could effectively fire under the keel of a ship and break the back of their targets with a single torpedo, increasing the overall effectiveness of the U-boat fleet. The TIII was also issued with program steering
FaT In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...
(''Flächenabsuchender Torpedo'') - - G7e(TIII Fat II) - and LuT (''Lagenunabhängiger Torpedo'') - G7e(TIII Lut II) - pattern running systems for convoy attacks. Though many opportunities had been missed due to the defects of the TII torpedo, with the new TIII U-boats were deadlier than ever.


G7es(TIV) ''Falke''

The TIV Model was the adjunct of the earlier TIII model in nearly every way. The TIV was not an ordinary straight-running torpedo, it ran at for and was the world's first operational acoustic homing torpedo, since it was introduced in March 1943, the same month and year as the American Mk-24 "Mine"
acoustic homing Acoustic homing is the process in which a system uses the sound or acoustic signals of a target or destination to guide a moving object. There are two types of acoustic homing: passive acoustic homing and active acoustic homing. Objects using pass ...
torpedo. Early in 1933 Germany started development and testing of acoustic homing mechanisms for torpedoes. From the outset of submarine warfare, submariners had dreamed of being able to aim and fire torpedoes without surfacing or using a periscope. The periscope gives away the location of a submarine, and a hull-penetrating periscope greatly weakens a submarine's pressure hull and limits the depths to which it can dive. U-boats also had to come to very shallow depths to use their periscopes, generally about , leaving them greatly exposed to bombing, depth charging, and even gunfire. With the introduction of ''Falke'', U-boats could remain more deeply submerged and fire at convoys with nothing to give away their position but the noise of their screws. Rather than aiming with a periscope, the torpedo could be roughly aimed at a sound contact as detected by a U-boat's hydrophones, and the homing mechanism could be trusted to find the target without the need for precise aiming. ''Falke'' worked much like a normal straight-running torpedo for the first of its run, after which its acoustic sensors became active and searched for a target. The sensitive sound-sensing equipment in ''Falke'' required the torpedo be as quiet as possible, hence it ran at only ; in addition, the firing U-boat was forced to stop its motors. ''Falke'' was intended to home on merchant targets, however, so its slow speed was not a great hindrance. Only known to have been fired in action by three U-boats, , and , although regarded as successful, resulting in the sinking of several merchants, and its performance rated satisfactory, ''Falke'' was rapidly phased out of service. It was replaced by the G7es(TV) "''Zaunkönig''" (referred to by the Allies as
GNAT GNAT is a free-software compiler for the Ada programming language which forms part of the GNU Compiler Collection (GCC). It supports all versions of the language, i.e. Ada 2012, Ada 2005, Ada 95 and Ada 83. Originally its ...
, for German Navy Acoustic Torpedo), which was faster and better able to home onto the sound of fast moving warships as well as merchant traffic. Though its period of operational service was brief, ''Falke'' was a proof of concept for the acoustic homing torpedo. Its introduction occurred only two months before the U.S. Navy achieved its initial combat success with the Mark 24 FIDO "mine." FIDO was not a mine, but a passive, acoustic-homing torpedo designed for use by long-range patrol aircraft. The initial success with the Mark 24 occurred on 14 May 1943, when a PBY-5 from VP-84 sank with the new weapon. Most sources indicate that the Germans' first combat success with the ''Zaunkönig'' (GNAT) did not occur until September 1943. While the Allies became aware in September 1943 that the Germans had brought GNAT into operational service, it was not until the capture of in June 1944 that they obtained reliable data on the German homing torpedo.


See also

*
List of World War II torpedoes of Germany List of World War II ''Kriegsmarine'' torpedoes ''Kriegsmarine'' torpedo designation system The first letter indicates the diameter: * G = 53 cm (21 in) * F = 45 cm (17.7 in) * H = 60 cm (23.7 in) * M = 75 cm ( ...
* Mark XI torpedo - reverse-engineered British copy *
Mark 18 torpedo The Mark 18 torpedo was an electric torpedo used by the United States Navy during World War II. The Mark 18 was the first Battery (electricity), electric storage battery torpedo manufactured for the US Navy and it was designed primarily for use ...
- reverse-engineered American copy * Type 92 Mod 2 torpedo - hybrid collaborative project between Japan and Germany


Citations


References

* * * {{Use dmy dates, date=June 2017 Weapons and ammunition introduced in 1936 World War II torpedoes of Germany