Johannes Plendl facts for kids

Johannes "Hans" Plendl (born 1900, died 1991) was a German scientist. He was a pioneer in radar technology. His inventions helped guide airplanes. These inventions made early German bombing successful in World War II.

Early life

Hans Plendl was born in 1900 in Munich, Germany. His family came from Northern Bavaria.

During World War I, Plendl briefly served in the Imperial German Navy. After the war, he started working for the Telefunken company. He became a radio and beam engineer.

Plendl studied how radio waves travel. He also researched radar beams. His work led him to name a new part of Earth's atmosphere. He is known for coining the term ionosphere. In the early 1930s, he helped develop radio communication for planes. This included the famous Hindenburg Zeppelin. He also worked on the Lorenz beam landing system. This system helped planes land safely. It later became known as the Instrument Landing System (ILS).

Guiding planes with radio beams

As Germany prepared for war, Plendl and other scientists saw a new use for radio beams. They realized beams could guide bombers to their targets. They began to develop a secret system called the "X-System."

Plendl used technology from his Lorenz beam system. He created a way to guide planes very accurately. This system helped bombers hit targets at night. It also worked well in bad weather. This important work was done for the German Air Force (Luftwaffe). It took place at experimental stations in Rechlin and Peenemünde.

Another system, called "Knickebein," was also developed. It used the Lorenz landing system for guidance. However, Knickebein was less accurate. It was also easier for enemies to block its signals. Both the X-System and Knickebein used tall towers. These towers were near the English Channel and the North Sea. They sent radar beams over targets in England. German bombers had special radar detectors. They also carried complex timing devices. Dr. Plendl invented these devices. They helped planes stay on course. They also told pilots the exact moment to drop their bombs.

The X-System was used in Poland. It helped hit military targets. But only a few planes had the "X-Device." This was the electronic part of the system inside the plane. During the The Battle of Britain, all three systems were used. These were the Knickebein, X-System, and Y-System. But British scientists found ways to fight back. Scientists like Reginald Victor Jones developed countermeasures. They could redirect or jam the German radio signals. This fight became known as the Battle of the Beams.

Dr. Plendl was given an important title for his work. He was named National Director of High Frequency Research.

Plendl was later removed from his position. This happened in December 1943. Some say it was after a big raid on Hamburg. The British used a new radar trick called Window or chaff. Others say Plendl was dismissed because he saved people. He claimed he needed their "expertise" for his beam program. This allowed him to save people from concentration camps. Plendl himself said he had an argument with a general. This argument was about a new type of anti-aircraft shell he developed.

Moving to America

When World War II ended, Plendl surrendered to the Americans. Like other German scientists, he was invited to the United States. He helped with American weapons development. This program was called "Operation Paperclip." U.S. government records showed that Plendl had often spoken against the Nazi government.

Plendl did something very special. He saved many people from the Dachau concentration camp. This included many Jewish people. He pretended he needed them for his projects. Many of these people were not scientists at all. Plendl was different from other German scientists. He actively opposed the Nazi government.

One important person Plendl saved was Hans Ferdinand Mayer. Mayer wrote the "Oslo Report." This report gave secret German information to the British in 1939. It was a big breach of German security. Mayer was arrested in 1943 for listening to the BBC. He had also criticized the Nazi government. Plendl appointed Mayer to lead a radio laboratory. Mayer was an expert in telephones, not radio. But Plendl still gave him the job.

Plendl finished his military career in the United States Air Force. He worked at their Cambridge Research Laboratory. He specialized in solid-state physics. This is the study of solid materials.

Later life

Plendl helped another scientist, Karl-Otto Kiepenheuer. They set up a network of stations across Europe. These stations watched the sun's activity. They wanted to predict disturbances in the ionosphere. These disturbances could interrupt military radio connections. Plendl and Kiepenheuer are seen as the founders of "space weather" science. Much of their network continued after the war.

In 1970, Plendl retired. He moved to Italy. R.V. Jones, the British scientist who jammed Plendl's beams, became a good friend. They wrote letters to each other often. They also worked together on several books.