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Kurt Waldemar Tank (24 February 1898 – 5 June 1983) was a German aeronautical engineer and test pilot who led the design department at Focke-Wulf from 1931 to 1945. He was responsible for the creation of several important Luftwaffe aircraft of World War II, including the Fw 190 fighter aircraft, the Ta 152 fighter aircraft-interceptor and the Fw 200 Condor airliner. After the war, Tank spent two decades designing aircraft abroad, working first in Argentina and then in India, before returning to West Germany in the late 1960s to work as a consultant for Messerschmitt-Bölkow-Blohm (MBB).
Tank had spent the four years of the war reading an unnamed physics book. He was very interested in hydrodynamics, the laws which govern theoretical Fluid dynamics. Tank wanted to apply the theories he had learned in real life by becoming a pilot. He applied many times for a transfer to the Fliegertruppe, however, unbeknownst to him, his senior officers wanted to retain him in the army because he was a great soldier. After the war, Tank studied at and graduated from the Technische Hochschule Berlin (now the Technische Universität Berlin) in 1923. Tank had studied electro-technology, but his recreational pursuit of gliding made him inclined towards aviation. Tank had also worked on building sailplanes with Akaflieg Berlin, and had started the Akaflieg (aviation) club at his university along with seven other students. These eight students had started the Akaflieg club to protect aviation development at their university from the rigid constraints imposed by the Treaty of Versailles. The Akaflieg club was supported mainly by army officer Adolf Baeumker, and also by their professor August von Parseval.
The other seven students who had established the club were , Werner Henninger, Pauleduard Punk, Seppl Kutin, Viktor Gohlke, Edmund Pfister and Georg Gillert. These eight students had created a workshop at the university's loft, where they started building two gliders while learning aeronautics from professors Emil Everling and Hans Reissner. Tank was building a monoplane which was strut-braced and had a big wingspan. Winter was building a monoplane without a tail, which he named Charlotte after the daughter of professor Parseval. This monoplane was the Akaflieg Berlin B1, which the group used to participate in the 2nd Rhön Competition organized by the Rhön-Rossitten Gesellschaft in 1922. Winter piloted the plane's flying wing model during the competition, but the plane was hit by a downdraft and it crashed near Gersfeld. The group then moved the plane on a wagon to Gotha. There, Gothaer Waggonfabrik had the plane sent to Berlin, where the group repaired it. Meanwhile, Tank had built a shoulder-wing plane with a big wingspan, which the group entered in the 1923 Rhön Competition. This plane was the Akaflieg Berlin B2 Teufelchen.
However, it was not possible to build both the B2 and B1 planes at the group's small workshop in the university's loft. The students also couldn't build it themselves, or their academics would be impacted. Therefore, Tank and Gillert went to the Albatros Flugzeugwerke factory in the Berlin suburb of Johannisthal. There, they met Robert Thelen, then an aviation world record holder who was a director at the company. However, Thelen did not want to build an entire sailplane for free, especially because it used wing warping Wing tip in place of Aileron. Tank and Gillert then went to Luft-Fahrzeug-Gesellschaft in Stralsund, who agreed to build the B2 Teufelchen ("Little Devil"). By building the B2, Tank had passed his preliminary exams; his academic output was assessed favorably by professors Parseval and . At the Rhön Competition in August 1923, Tank had to Forced landing the B2 on unfavorable terrain when he was practicing flying. The B2 was wrecked and the group had used up all their money by then. The group was later able to repair the B2 and fly it in Rositten. Tank then trained and qualified for a flying license at Staaken, flying the DFS Kranich with Rudolf Rienau as his trainer.
Such testing was first done at the in Berlin. This testing was later done at in Hamburg with bigger models. Tank towed varying designs for 1000s of kilometres; these tests verified his ideas and Rohrbach incorporated them into their production models. The changed designs had a keel which spread landing impact over longer durations and lengths, lowering landing pressure on the hull without impacting takeoff performance. These changes were implemented on the Rohrbach Ro V Rocco, Rohrbach Romar, Rohrbach Ro XI Rostra and both variants (I and II) of the Rohrbach Ro VII Robbe. After more testing and with observations on the aforementioned planes, Tank introduced an improved design with a modified empennage and wings. The older designs used a constant chord rectangular wing, while the newer designs used a tapered wing which had a significantly lower weight. The new tapered wings had higher taper at an invariant thickness. These modifications enhanced flight handling and also allowed for more maneuverability.
The second Ro IX prototype crashed in January 1927 with as its pilot. As a result, the dihedral angle was eliminated. Ernst Udet then flew the plane and issued a positive assessment on 1 July 1927. Udet also noted down a few potential improvements, namely greater aileron control, enhanced lateral stability and better handling during slip maneuvers. After Udet's feedback was implemented, the Ro IX was tested and approved for flying by the German Aerospace Center. On 15 July 1927, pilot Paul Bäumer crashed in the Ro IX; Tank said Bäumer had not considered that such large planes can execute spin maneuvers only at low throttle. Tank represented Rohrbach in an inquiry into the incident. At the inquiry, fighter pilot Friedrich Mallinckrodt questioned why a fighter aircraft was designed as a monoplane and not a biplane. Many other WWI fighter pilots also said a monoplane fighter was very dangerous and not suitable for flight. Tank reminded the fighter pilots they had flown the Fokker D.VIII, a monoplane, with great success during the war; thereafter, the issue of a monoplane fighter was settled.
The Rohrbach Ro VII Robbe II, with a sharp taper and an aspect ratio of 8.40, was built for research and setting records. Aviation experts cautioned Rohrbach about the very high taper and said it would stall on one wing, so did Landmann. Tank said the tapered wings provided much more control to the pilots because the incremental drag would be quite lower compared to rectangular wings. Landmann, initially hesitant, later found the Robbe II to be very maneuverable. Udet wanted to attempt a trans-Atlantic flight, he teamed up with Tank and chose the Robbe II as his plane. Udet flew his first practice flight on the same day, after Tank had told Udet the aircraft had a high landing speed. Udet executed both the takeoff and sky flying properly, but he slowed down on his landing approach. The plane stalled at approximately and dropped into the water. It seemed as if the plane had sunk, but then it appeared again on the water with only little damage. The aircraft hadn't tilted towards either wing, it had stayed straight while its altitude dropped.
Three weeks thereafter, the two attempted a record flight, with Udet as the pilot and Tank as the navigator. Tank ensured that Udet did not have either a slow takeoff speed or rate of ascent. The flight was expected to take ten hours and cover a distance of . They were flying a preset triangular route three times from Copenhagen to the Swedish coast and back, with officials from the Fédération Aéronautique Internationale watching. They were flying well, but then they heard a sharp sound, the engines buzzed loudly and the aircraft began shaking. Tank and Udet managed to regain control, but then the plane quickly lost height and dropped into the water. The two propellers had blown off and the engines had shut down, but the plane had still landed and did not sink. There was a small fire because the fuel tanks had been hit by the propellers' pieces. The idea of attempting a trans-Atlantic flight was dropped.
On 14 October 1930, Tank was working with test pilot Eberhard Mohnicke in Augsburg to know more about the BFW M.22. Mohnicke then went to fly the M.22 once again from Augsburg to Landsberg and back. Mohnicke crashed on the landing approach when returning. In April 1931, another M.20 crashed and BFW shut down. Messerschmitt, a unit of BFW, continued operating. However, Tank left the company in September 1931 because of creative differences with Willy Messerschmitt, its eponymous founder. Messerschmitt believed the ultralight aviation idea was universally applicable, Tank believed it was not prudent considering the rapidly growing size of aircraft.
Tank then test flew the Focke-Wulf Fw 47 Höhengeier developed by Henrich Focke. Focke believed the aircraft could not fly spin maneuvers because of its unique wing shape. Tank broadened the tail and used the rudder to show the aircraft could be spun. Tank then started work on the design of the Focke-Wulf Fw 44 Stieglitz, a biplane trainer. While flying the aircraft at Bremen, Tank found it would shake uncontrollably. The two separate elevators were revealed to be the problem, so they were merged into one unit. After the Fw 44 was moved to production in 1934, Tank worked on test piloting the Albatros L103. During this period, Tank also began building a team which could make complex aircraft like airliners because the new German government did not restrict aviation. Tank convinced Focke-Wulf director Werner Naumann to fund these new projects. Tank brought over Hans Schuberth, Andreas Faehlmann and other engineers to Focke-Wulf. New divisions and teams were created to build these aircraft, with Tank managing and advising them.
In 1934, Tank's Focke-Wulf Fw 56 Stösser advanced trainer began production.Munson, K. Fighters Between the Wars 1919-39 1977 p. 144 In 1935, Ernst Udet used the Stösser to demonstrate the utility of Dive bomber to German officials. A total of 900 to 1,000 Stössers were built, but none are extant today. Tank then wanted to build a full-metal aircraft so he could modernize the company's production processes and upskill its employees. Three prototypes of the Focke-Wulf Fw 57, a Heavy fighter Attack aircraft, were built as a result. However, production models of the Fw 57 were not built because the RLM (Nazi Aviation Ministry) had decided it would induct Light aircraft strike aircraft. In 1934, Tank also conceptualized the Focke-Wulf Fw 159, a single seater chase fighter according to the RLM's requirements. Tank modeled the Fw 159 after the Polish PZL P.24, considered the best fighter during the early 1930s. However, it was not inducted by the RLM due to its heaviness and high drag.
In 1942, Tank was piloting an Fw 190 to Berlin, while trying to learn the night combat method developed by Major Hajo Herrmann at the Döberitz military training area. When Tank was returning to Langenhagen, the Fw 190 began leaking fuel somewhere over the Elbe river. Tank was growing unconscious and could not spot the nearby town of Stendal. He struggled for some time but managed to land at Langenhagen, and aircrew found him passed out in the cockpit. A fuel line of the Fw 190 had been dripping fuel, and the aircraft had fuel levels sufficient only for a single circuit. If the aircraft had flown for sometime more, the engine would have shut down.
Ludwig Roselius, chairman and 46% majority shareholder of Focke-Wulf via Kaffee HAG, and Barbara Goette - his closest confidante - met with Tank in the Marcus-Allee, Bremen on many occasions.Leidig, Ludwig. Bombshell. sbpra, 2013; pp. 21-22.
When the war was almost ending, the US Army captured Bad Eilsen and discovered Tank still working along with 2,000 engineers. Colonel Marco Ferrari found a letter written by Tank proposing the construction of more fighters. Ferrari told Tank the Combined Bomber Offensive might just have failed if the Germans had built more fighters and heeded Tank's recommendation.
When those negotiations proved unsuccessful, he accepted an offer from Argentina to work at its aerotechnical institute, the Instituto Aerotécnico in Córdoba under the name of Pedro Matthies.
Tank moved to Córdoba in central Argentina in late 1946, with many of his Focke-Wulf co-workers. He also reportedly recommended Ronald Richter, who proposed to power airplanes with nuclear energy, to the Argentine officials.Mario Mariscotti (2025). 9781545569948, CreateSpace Independent Publishing Platform. ISBN 9781545569948 Richter would later be involved in the Huemul Project, which was eventually proven to be a fraud.
The Instituto Aerotécnico later became Argentina's military aeroplane factory, the Fábrica Militar de Aviones. While there, Tank designed the IAe Pulqui II based on the Focke-Wulf Ta 183 design that had reached mock-up stage by the end of World War II; it was a state-of-the-art design for its day, but the project was cancelled after the fall of Peron in 1955. When President Juan Perón fell from power, the ex-Focke-Wulf team dispersed, with many, including Tank, moving to India. First he worked as Director of the Madras Institute of Technology, where one of his students was future President of India Abdul Kalam, who went on to design the indigenous Satellite Launch Vehicle (SLV) and lead the Integrated Guided Missile Development Programme. Tank later joined Hindustan Aeronautics, where he designed the Hindustan Marut fighter-bomber, the first military aircraft constructed in India. The first prototype flew in 1961, and the Marut was retired from active service in 1985. Tank left Hindustan Aeronautics in 1967 and by the 1970s, he had returned to live in West Berlin, basing himself in Germany for the rest of his life. He worked as a consultant for MBB..
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