Original German WWII U-Boat G7A (TII) Torpedo Engine

Item Description

Original Item: Only One Available. This is an incredibly rare steam driven engine for a German WWII U-Boat G7A (TII) torpedo. There are only 174 known G7A (TII) torpedoes still in existence. 

The G7a(TI) was the standard issue Kriegsmarine torpedo during the early years of World War II. It was a steam-powered design, using a wet heater engine burning decaline, with a typical range of about 7,500 metres (24,600 ft) while running at 40 knots (74 km/h; 46 mph). It was replaced beginning in 1942 by the electrically powered G7e torpedo, which did not leave a trail of bubbles in the water and thus did not reveal the location of the submarine. G7a's remained in service in other roles, including surface ships, until the end of the war.

The G7a (TI) torpedo was 533.4 mm (21 in) in diameter, 7163 mm (23 ft 6 in) in length (with a type Ka or Kb warhead and Pi1 or Pi2 pistol), the warhead holding a charge of approximately 280 kg (617lbs) of so-called Schießwolle 36. It was Kriegsmarine's first operational torpedo (hence "TI" = Torpedo number one), and the standard issue torpedo for all German U-boats and surface torpedo-bearing vessels from ca 1935 to the end of WW2.

The torpedo was of a straight-running unguided design, controlled by a gyroscope. The TI was of variable speed, running a distance of 5,000 m at 81 km/h (5,500 yd at 44kt), 7,500 m at 74 km/h (8,250 yd at 40 kt), and 12,000 m at 55.6 km/h (13,200 yd at 30 kt). The 44 kt setting was used only by torpedo boats like the Schnellboote on torpedoes with a reinforced engine.

The TI was the last naval torpedo of German design in operational use with the traditional standard wet heat method of propulsion. The torpedo was powered by an engine fed by a mixture of compressed air and steam. Decaline fuel was burning in a combustion chamber, creating steam from fresh water. The torpedo's speed was determined by the level of pressure (three settings for 30/40/44 kn) from the low-pressure regulator feeding air to the bottom of the combustion chamber. The resulting superheated steam powered a four cylinder reciprocating engine, in turn powering a pair of contra-rotating propellers.

Though this system of propulsion gave the TI great speed and endurance – the greatest of any production model German torpedo of World War II – it had the distinct disadvantage of being very noisy and leaving a long wake of bubbles, common to most torpedoes of the period, with the exception of the Japanese Type 93 and submarine Type 95, which were fueled by enriched oxygen. For U-boats, this relegated the TI for use mainly at night, when its wake was least noticeable, so as to not give away the element of surprise and the location of the submarine that fired it. During daytime, the electric torpedoes were favored.

The TI was initially fitted with a combined mechanical/magnetic exploder, which was inadequately tested (like the U.S. Navy's Mark 14), having never been live fired.[1] In addition, because the G7a's performance had never been assessed, between deep running and premature explosions (both also familiar to the Mark 14),[3] the G7a suffered a thirty percent failure rate early in World War II.[4] The response of the high command, ignoring complaints and blaming the operators, was also common to the U.S. Pacific Fleet's Submarine Force.[6] The problems were so serious, Admiral Dönitz said, "...never before in military history has a force been sent into battle with such a useless weapon."

There is at least one recorded case of a U-boat being bombed based upon her position being given away by a TI's wake. On 14 September 1939, U-30 was attacked by loitering United Kingdom Fairey Swordfish naval bombers when she fired a TI from her stern torpedo tube at the SS Fanad Head. U-30 was undamaged in the attack and served until she was scuttled at the end of the war.

Though the T1 could easily be spotted by surface ships, it remained the torpedo of choice for some U-boat captains until the release of the G7e(TIII) electric torpedo in 1942, largely due to the inferior performance and tendency of the G7e(TII) (the wakeless electric torpedo available to U-boats from 1939–1942) to fail to detonate, both on proximity and contact fuses.

The TI were also issued in versions with programmed-steering gyroscopes, using the Fat I ladder search pattern and the Lut I or Lut II pattern running for attacking convoys.
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