Karl Wilhelm Otto Lilienthal (23 May 1848 – 10 August 1896) was a German pioneer of aviation who became known as the "flying man".

Newspapers and magazines published photographs of Lilienthal gliding, favourably influencing public and scientific opinion about the possibility of flying machines becoming practical.

[16] Fascinated by the idea of manned flight, Lilienthal and his brother made strap-on wings, but failed in their attempts to fly.

He attended the regional technical school in Potsdam for two years and trained at the Schwarzkopf Company before becoming a professional design engineer.

In 1867, Lilienthal began experiments in earnest on the force of air, but interrupted the work to serve in the Franco-Prussian War.

The filing of a U.S. Patent in 1894 by Lilienthal directed pilots to grip the "bar" for carrying and flying the hang glider.

[19] The A-frame of Percy Pilcher and Lilienthal echoes in today's control frame for hang gliders and ultralight aircraft.

[20] At the beginning, in the spring of 1891, Lilienthal managed the first jumps and flights on the slope of a sand pit on a hill between the villages of Derwitz and Krielow in Havelland, west of Potsdam (52°24′48″N 12°49′22″E / 52.41333°N 12.82278°E / 52.41333; 12.82278).

During his short flying career, Lilienthal developed a dozen models of monoplanes, wing flapping aircraft and two biplanes.

Lilienthal controlled them by changing the center of gravity by shifting his body, much like modern hang gliders.

While his lifelong pursuit was flight, Lilienthal was also an inventor and devised a small engine that worked on a system of tubular boilers.

[26] Lilienthal performed his first gliding attempts in the spring of 1891 at the so-called "Spitzer Berg" near to the villages of Krielow and Derwitz, west of Potsdam.

[32] On top of the hill was built a small temple-like construction, consisting of pillars supporting a slightly sloping round roof.

[33] Lilienthal's brother Gustav and the old mechanic and assistant Paul Baylich attended the unveiling ceremony on 10 August 1932 (36 years after Otto's death).

Reports of Lilienthal's flights spread in Germany and elsewhere, with photographs appearing in scientific and popular publications.

Many people from around the world came to visit him, including Samuel Pierpont Langley from the United States, Russian Nikolai Zhukovsky, Englishman Percy Pilcher and Austrian Wilhelm Kress.

Lilienthal corresponded with many people, among them Octave Chanute, James Means, Alois Wolfmüller and other flight pioneers.

Lilienthal had previously had difficulty in recovering from this position because the glider relied on weight shift which was difficult to achieve when pointed at the ground.

[35] Paul Beylich, Lilienthal's glider mechanic, transported him by horse-drawn carriage to Stölln, where he was examined by a physician.

[37] Lilienthal's research was well known to the Wright brothers, and they credited him as a major inspiration for their decision to pursue manned flight.

It is true that attempts at gliding had been made hundreds of years before him, and that in the nineteenth century, Cayley, Spencer, Wenham, Mouillard, and many others were reported to have made feeble attempts to glide, but their failures were so complete that nothing of value resulted.Before its closure in 2020, Berlin's then busiest airport, Berlin Tegel "Otto Lilienthal" Airport, was named after him.

[42] A German Air Force tanker, Airbus A310 MRTT registration 10–24, has been named "Otto Lilienthal" in his honour.

[43][44] An authentic replica of the Normalsegelapparat made by the Otto Lilienthal Museum have been investigated by the German Aerospace Center in wind tunnel and flight tests.