The Type IX U-boat was designed by Nazi Germany's Kriegsmarine in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern United States in an attempt to disrupt the stream of troops and supplies bound for Europe. It was derived from the Type IA, and appeared in various sub-types. Type IXs had six torpedo tubes; four at the bow and two at the stern. They carried six reloads internally and had five external torpedo containers (three at the stern and two at the bow) which stored ten additional torpedoes. The total of 22 torpedoes allowed U-boat commanders to follow a convoy and strike night after night. Some of the IXC boats were fitted for mine operations; as mine-layers they could carry 44 TMA or 66 TMB mines. Secondary armament was provided by one deck gun with 180 rounds. Anti-aircraft armament differed throughout the war. They had two periscopes in the tower. Types IXA and IXB had an additional periscope in the control room, which was removed in Type IXC and afterward. These long range boats were frequently equipped with Focke-Achgelis Fa 330 rotor kite towed rotary-wing aircraft. Type IXA List of Type IXA submarines DeSchiMAG AG Weser of Bremen built eight Type IXA U-boats. - scuttled 8 May 1945 - scuttled 5 May 1945 - sunk 14 September 1939 - sunk on 13 October 1939 by a mine - sunk by depth charges on 5 February 1940 - sunk on 13 October 1939 by depth charges - sunk on 30 July 1943 - sunk by mine on 13 March 1940 Type IXB Type IXB was an improved model with an increased range. It was the most successful version overall with each boat averaging a total of over sunk. Notable IXB boats included commanded by Reinhard Hardegen, which opened up the attack in the US waters in early 1942 known as Operation Drumbeat, and operating off Freetown, Sierra Leone under the command of Günter Hessler, which had the most successful single mission of the war ever with close to sunk. List of Type IXB submarines DeSchiMAG AG Weser of Bremen built 14 Type IXB U-boats. Thirteen were sunk in the course of the war. Type IXC The Type IXC was a further refinement of the class with storage for an additional 43 tonnes