Siegfried and Walter Günter

Dr. Siegfried Günter (8 December 1899 – 20 June 1969) and Walter Günter (8 December 1899 – 21 September 1937) were German twin brothers and pioneering aircraft designers. Walter was responsible for the world's first rocket-powered and turbojet airframes, projects funded by Nazi Germany. Siegfried was the father of the "thrust modulation theory".

Siegfried and Walter Günter were born on 8 December 1899 in Thuringia. Avid flight enthusiasts, at 16 they had developed their own propeller theories. Both served in the First World War, where they were captured by the British Army and each became a prisoner of war.

The brothers would be educated in mechancial engineering at the Institute of Technology Hannover, specializing in aircraft design and aerodynamics. It was there that Siegfried designed his first aircraft with fellow students Walter Mertens and Werner Meyer-Cassel, the glider H 6. Their talents were first recognised by Paul Bäumer who was impressed by the performance of the H 6 when he saw it being flown at Wasserkuppe. Bäumer offered the brothers, Mertens, and Meyer-Cassel jobs with his company Bäumer Aero in Berlin. There they began designing motor gliders and then increasingly fast sports planes, including one in which Bäumer himself was killed in a crash in 1928. By 1925 Siegfried had designed first "Buzzing Wind" airplane for the Deutscher Rundflug 1925 competition, which featured the first elliptic design based on Prandtl's 1918 theory.

On 16 January 1931, Ernst Heinkel recruited Siegfried Günter to work for his Heinkel company in , and Walter joined the company on 31 July 1931, where he was in charge of developing low and high-speed wind tunnels. There they were to design some of the most important and famous designs associated with the company, including the Heinkel He 51, He 70, He 112, He 100, and the He 111. Walter designed the first ever retractable landing gear in Germany for the He 70, an aircraft mainly designed by Siegfried.

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