G7e torpedo
The G7e or more appropriately the G7e/T2, G7e/T3, and G7e/T4 Falke torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

es were, with the exception of the T4 model, the standard torpedoes for Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. All of the G7e models shared standardized dimensions for all German torpedoes designed for use by U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s during World War II, they measured 53.3 cm (21 inches) in diameter, 7.16 m in length, and carried a Hexanite
Hexanite was a castable German military explosive developed early in the 20th century before the First World War for the Kaiserliche Marine, intended to augment supplies of trinitrotoluene , which were then in short supply. Hexanite is significantly more powerful than TNT on its own...

 warhead of 280 kg. All were powered by 100 hp (75 kW) electric motors and lead-acid batteries
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

 which needed constant maintenance to maintain their reliability. Additionally, the batteries of these torpedoes needed to be preheated to a temperature of 30 °C (85 °F) to operate with maximum speed and range, though generally this was a non-issue as U-boats had the element of surprise and often had the advantage of firing the first shot.


The T2 model of the G7e was in service with German U-boat fleets from the first day of World War II. In stark contrast with the G7a
G7a torpedo
The G7a or G7a/T1 was the standard issue Kriegsmarine torpedo during the early years of World War II.- Design :The torpedo was 53.3cm in diameter, 7.163 m in length, and with a warhead of 280 kg of Hexanite, and was standard issue for all U-boats of the war.The torpedo was of a straight-running...

  steam driven torpedo, the T2 left no visible stream of bubbles to alert ships they were under attack, and was virtually silent; however, these were the T2's only advantages over the G7a torpedo. The T2 in all other respects performed abysmally when compared to the G7a. Its range was much shorter than the G7a's at only 3000 m, and it ran much slower at 30 kt (55 km/h).

Poor range and speed were not the T2's only problems. Both of its exploders were terribly flawed. The magnetic influence mechanism, designed to allow the torpedo to run under the keel of a ship and detonate, breaking the ship's back, was totally inconsistent; often a T2 would detonate prematurely, or not at all. This led the BdU
The abbreviation BDU may refer to:*Battle Dress Uniform, United States' combat uniforms.*Befehlshaber der U-Boote , commander-in-chief of Germany's submarine fleets in WW-II.*FAA location identifier for Boulder Municipal Airport...

 to order all G7e/T2 torpedoes be fired only for contact detonation. However, the contact pistol of the T2 often did not work, either. The depth-keeping equipment of the T2 often failed as well, leading T2s to miss their targets by running too deeply under a target. Estimates of the failure rate of T2 torpedoes for one reason or another range between 20% and 40%.

Nevertheless, the German Navy, after much prodding by German U-boat Command (BdU
The abbreviation BDU may refer to:*Battle Dress Uniform, United States' combat uniforms.*Befehlshaber der U-Boote , commander-in-chief of Germany's submarine fleets in WW-II.*FAA location identifier for Boulder Municipal Airport...

), poured resources into correcting the T2's flaws. Gradually, it improved, and by the end of the Norwegian Campaign problems with the contact exploder and depth-keeping gear had been solved, as well as significant strides made in improving the magnetic proximity feature. At the same time, the T2's range was increased from 3000 m to 5000 m and eventually 7500 m. By that time, however, the T2 was already being phased out of production.


Improvements in the design of the G7e/T2 were incorporated into the production of the next model of electric torpedo for Germany's U-boat fleet. Introduced in 1942, the T3 represented a vast improvement over the early T2. The faulty exploders from the T2 were scrapped in favor of a new design.

The T3 had a range of 5000 m and could achieve 30 kt. With the improved design of the T3 and the new exploder, the G7a steam torpedo was totally superseded and was rarely used for the remainder of the war. Using the T3'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 T3 could be fitted with both the FaT (Flächenabsuchender Torpedo) and LuT (Lagenunabhänger Torpedo) pattern running systems for convoy attacks.

Though many opportunities had been missed due to the defects of the T2 torpedo, with the new T3 U-boats were deadlier than ever.

G7e/T4 Falke

The T4 Model was the adjunct of the earlier T3 model in nearly every way. The T4 was not an ordinary straight-running torpedo, however; it was the world's first acoustic homing torpedo. It ran at 20 kt (37 km/h) for 7500 m and was introduced in March 1943.

In early 1933, Germany started development and testing of acoustic homing mechanisms for torpedoes. From the outset of submarine warfare, submariners had dreamt 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 15 m, 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 400 m 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 20 kt (37 km/h); in addition, the firing U-boat was forced to stop its motors. Falke was intended to home on merchant targets, however, so it is slow speed was not a great hindrance.

Only known to have been fired in action by three U-boats, U-603, U-758
German submarine U-758
German submarine U-758 was a Type VIIC U-boat built for the German Kriegsmarine for service during World War II. Commissioned on 5 May 1942, she served with the 6th U-boat Flotilla until 1 November as a training boat, and as a front boat until 14 October 1944 mostly under the command of...

, and U-221, 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/T5 "Zaunkönig"
G7es torpedo
The G7es or Zaunkönig T-5 was a torpedo employed by German U-boats during World War II. It was known as the GNAT to the British.- Description :...

 (referred to by the Allies as GNAT, for German Naval Acoustical 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. (It was designated a mine for security reasons.) The initial success with the Mark 24 occurred on 14 May 1943, when a PBY
PBY Catalina
The Consolidated PBY Catalina was an American flying boat of the 1930s and 1940s produced by Consolidated Aircraft. It was one of the most widely used multi-role aircraft of World War II. PBYs served with every branch of the United States Armed Forces and in the air forces and navies of many other...

-5 from VP-84 sank U-640 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 U-505 in June 1944 that they obtained reliable data on the German homing torpedo.
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