Johannes Plendl

Johannes "Hans" Plendl (December 6, 1900 – 1992), German radar pioneer, was the scientist who made possible the early German bombing successes in World War II.

Plendl was born in 1900 in Munich, German Empire to parents from Northern Bavaria. The surname is most likely a truncated Bavarian dialect form of "Plendlein." As a young man, Plendl began his career as a radio and beam engineer for Telefunken corporation. His early research into radio and radar beams necessitated additional names for newly discovered levels of the earth's atmosphere, and Plendl is generally credited with coining the term ionosphere.

With the rise of the National Socialists in Germany, the promise of Plendl's research was quickly noted by the Luftwaffe. Hermann Goering appointed Plendl "Staatsrat and Plenipotentiary of Long Range Bombing and High Frequency Research," and ordered Plendl to come up with advanced navigation devices for German warplanes.

Plendl did not disappoint. His first invention, the "knickebein" (German for "crooked leg") though simple, was immensely effective during the early days of the war. The system employed transmitter towers on the English channel and North Sea to transmit radar beams over targets in England. German bombers carried primitive versions of the radar detector (also invented by Plendl) and complex timing devices, the former to keep them on a path to their targets even on dark nights; the latter to tell the crew with precision when to unload the bombs.

Later, more complex versions of the system (called X-Geraet, Y-Geraet, and Wotan) were also used with success, but this success waned a bit after the English successfully decoded top-secret German communications and began to employ sophisticated devices to jam the German radar beams. Nevertheless, Plendl's inventions made possible the terrible destruction of cities like Coventry and Warsaw, and the uncertainty of life in London during The Blitz during the early part of the war.

During the later days of World War II, Plendl worked on the teams developing other German "wonder weapons," most notably the V-1 and V-2 rockets. He also worked to develop radar systems (code named: Freya, Erstling, and Lorenz) to track incoming bombers, which were wreaking havoc on German cities during 1943-1944. It has also been posited that Plendl invented a more sophisticated anti-aircraft, or flak system during the waning days of the war, one that was not implemented due to internecine rivalries within the Luftwaffe.

Together with the German solar physicist Karl-Otto Kiepenheuer (1910-1975), Plendl founded a chain of solar observatories to predict the best usable frequency bands for military short-wave radio from the observed characteristics of Solar Activity. Plendl and Kiepenheuer can thus be seen as the fathers of the science of space weather.

In 1944, Adolf Hitler removed many scientists including Plendl and Plendl's colleague Wernher von Braun from their posts, allegedly for being too candid or "defeatist" about German chances for victory.

At the end of the war, like other German scientists, Plendl was invited to come to the United States to divulge the radar and other technologies he developed as part of "Operation Paperclip." Afterwards, Plendl worked at the Air Force Cambridge Research Laboratory for many years in the field of solid-state physics, then returned to his native Germany in 1970. R.V. Jones, the British scientist who had worked on the other end of the channel to jam Plendl's beams, became a good friend. Johannes Plendl died in 1992.

References

*Ken Wakefield, "Pfadfinder: Luftwaffe Pathfinder Operations Over Britain, 1940-44". ISBN 0-7524-1692-8
*Louis Brown, "A Radar History of World War II". ISBN 0-7503-0659-9
*R.V. Jones, "Most Secret War". ISBN 1-85326-699-X
*Michael P. Seiler, 2006; "Kommandosache "Sonnengott". Geschichte der deutschen Sonnenforschung im Dritten Reich und unter alliierter Besatzung." Frankfurt: Wissenschaftlicher Verlag Harri Deutsch
*Fritz Trenkle, "Zum 90. Geburtstag von Hans Plendl", Funkgeschichte, 78: 3--5, 1991.