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The G7e torpedo was the standard electric torpedo used by the German ''
Kriegsmarine The (, ) was the navy of 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 It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic.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 branches, along with the a ...
'' submarines in
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
. 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 were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ...
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. HND was used extensively by the Empire of Japan, Japanese during World War II but was discontinued due to its toxicity. Preparation Dinitrod ...
and
TNT Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...
. 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 the
Royal Oak The Royal Oak is the English oak tree within which the future King Charles II of England hid to escape the Roundheads following the Battle of Worcester in 1651. The tree was in Boscobel Wood, which was part of the park of Boscobel House. C ...
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 Comma ...
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 HMS ''Nelson'' 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 A battleship is a large armored warship with a main battery consisting of large caliber guns. It dominated naval warfare in the late 19th and early 20th centuries. The term ''battleship'' came into use in the late 1880s to describe a type of ...
, seven
heavy cruiser The 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 caliber, whose design parameters were dictated by the Washington Naval Tr ...
s, seven
destroyer In naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed in ...
s and some cargo ships 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 Comma ...
), 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 spec ...
(''Flächenabsuchender Torpedo'') - - G7e(TIII Fat II) - and
LuT Lut may refer to: * Lut, a prophet mentioned in the Qur'an * Lut, Iran, a village in Amol County, Mazandaran Province * Lut (Lowlet), a village in Sari County, Mazandaran Province, Iran * Dasht-e Lut, a desert in southeastern Iran * Lut, a small t ...
(''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 a system which uses the acoustic signature (sound) of a target to guide a moving object, such as a torpedo. Acoustic homing can be either passive or active in nature. Using passive homing, the system is designed to move either t ...
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 A gnat () is any of many species of tiny flying insects in the dipterid suborder Nematocera, especially those in the families Mycetophilidae, Anisopodidae and Sciaridae. They can be both biting and non-biting. Most often they fly in large num ...
, 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 The Consolidated PBY Catalina is a flying boat and amphibious aircraft that was produced in the 1930s and 1940s. In Canadian service it was known as the Canso. It was one of the most widely used seaplanes of World War II. Catalinas served w ...
-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 (30 ...


Citations


References

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