Johannes Plendl

Johannes Plendl (also Hans Plendl ; * December 6, 1900 ; † May 10, 1991 ) was a German physicist and inventor. He invented several radio navigation methods with the help of which the Wehrmacht Air Force could carry out its major attacks on the United Kingdom in the first half of World War II .

Life

After studying physics at the Technical University of Munich and doing his doctorate with Jonathan Zenneck , Plendl took up a position in Berlin-Adlershof at the German Aviation Research Institute (DVL) at the Berlin-Johannisthal airfield . Dr.-Ing. In 1934, Plendl became head of department F (radio research) at the DVL branch in Rechlin . In 1936 this became part of the Luftwaffe's test center (E -stelle), where he developed the X-procedure (code name "Wotan I") for the precise bombing, for which Telefunken manufactured the transmitters and receivers. The procedure used four guide beams at frequencies from 66 to 77 MHz, which corresponds to a wavelength of 4.5 to 3.9 meters. A square 300 meters wide could be hit at a distance of 350 km. After the tests were completed, the X-procedure was introduced in the Luftwaffe in 1938 .

The during the air raids on England - including the " Operation Moonlight Sonata " on 14./15. November 1940 against Coventry - transmitters used for the X procedure were located near Cherbourg (beacon) and near Calais . Plendl's employees and mostly he himself were staying in Poix-de-Picardy , France , where Kampfgruppe 100 was located, which provided the “pathfinder” planes guided by a beacon. This presence was necessary because the system was soon effectively disrupted by the British. The British specialist responsible for this was Reginald Victor Jones . He and Plendl became friends after the war.

During the war, Plendl and his colleagues at the Rechlin electrical station developed a tactical two-dimensional location method "Y" that determined the position from the measured distance to two fixed transmission locations (see hyperbola navigation ). It was tested under the name Erika with an accuracy of 0.01 degrees, but was no longer used.

Plendl's successes were recognized by Reichsmarschall Hermann Göring . He was given the title of Prussian State Council early on . At the end of 1942 he was appointed representative of radio frequency research. After the British success in the attack on Hamburg ( Operation Gomorrah ), which had been made possible with improved radar technology by Düppel (radar deception) , he was deposed as authorized representative in December 1943 and replaced by Abraham Esau .

In the initial phase of the war, Plendl and his deputy Walter Dieminger fulfilled their long-cherished wish to set up an advisory and forecast system for shortwave, which is considered to be unreliable. On their behalf, Karl Rawer developed an analytical calculation method that determined the probability of a satisfactory connection depending on the time, month, distance, solar activity and frequency. Karl-Otto Kiepenheuer set up a network of equipped observation stations to record the changing emissions of the sun, with which it was hoped to be able to predict disturbances in the ionosphere .

After the war, Plendl and his family were taken to the United States at the Air Force Cambridge Research Laboratory . To the astonishment of his new employers, he refused to continue using radio navigation. He insisted on working with his own ideas in the field of solid state physics . After years without recognition, he was the first to receive the research award from his US Airforce department. After his retirement, Hans Plendl lived in Merano .

literature

Michael P. Seiler: Command matter sun god. History of German solar research in the Third Reich and under Allied occupation. Frankfurt am Main 2007, ISBN 3-8171-1797-3 .
Fritz Trenkle von Hüthig: The German radio control procedures until 1945. 1988.
Reginald Victor Jones: Most secret was. Coronet paperback edition, 1979, ISBN 0-340-24169-1 .

Web links

1-minute interview with Plendl on video.aol.de

Individual evidence

^ Helmut Maier : Research as a weapon. Armaments research in the Kaiser Wilhelm Society and the Kaiser Wilhelm Institute for Metal Research 1900–1945 / 48. Vol. 2. Wallstein-Verlag, Göttingen 2007, ISBN 978-3-8353-0109-2 , p. 776 ( online ) and p. 1012.
^ Kai Handel: The Rotterdam working group and the development of semiconductor detectors. Radio Frequency Research in the Military Crisis 1943–1945. In: Helmut Maier (Ed.): Armaments research in National Socialism. Organization, mobilization and delimitation of the technical sciences. Wallstein, Göttingen 2002, ISBN 3-89244-497-8 ( History of the Kaiser Wilhelm Society in National Socialism. Vol. 3), pp. 250–270, here pp. 255f.

personal data
SURNAME	Plendl, Johannes
ALTERNATIVE NAMES	Plendl, Hans
BRIEF DESCRIPTION	German physicist and inventor
DATE OF BIRTH	December 6, 1900
DATE OF DEATH	May 10, 1991

[1] Helmut Maier : Research as a weapon. Armaments research in the Kaiser Wilhelm Society and the Kaiser Wilhelm Institute for Metal Research 1900–1945 / 48. Vol. 2. Wallstein-Verlag, Göttingen 2007, ISBN 978-3-8353-0109-2 , p. 776 ( online ) and p. 1012.

[2] Kai Handel: The Rotterdam working group and the development of semiconductor detectors. Radio Frequency Research in the Military Crisis 1943–1945. In: Helmut Maier (Ed.): Armaments research in National Socialism. Organization, mobilization and delimitation of the technical sciences. Wallstein, Göttingen 2002, ISBN 3-89244-497-8 ( History of the Kaiser Wilhelm Society in National Socialism. Vol. 3), pp. 250–270, here pp. 255f.