Otto Lilienthal

Lilienthal's work led to his developing the concept of the modern wing. His flight attempts in 1891 are seen as the beginning of human flight and the "Lilienthal Normalsegelapparat" is considered the first airplane in series production, making the Maschinenfabrik Otto Lilienthal in Berlin the first airplane production company in the world. He has been referred to as the "father of aviation" and "father of flight". On 9 August 1896, Lilienthal's glider stalled and he was unable to regain control. Falling from about 15 m, he broke his neck and died the next day.

• Name — Otto Lilienthal • Birth Name — Karl Wilhelm Otto Lilienthal • Born — 23 May 1848 • Birthplace — Anklam, Province of Pomerania, Kingdom of Prussia, German Confederation • Died — 10 August 1896 • Place of death — Berlin, Province of Brandenburg, Kingdom of Prussia, German Empire • Death Cause — Cervical fracture sustained in a hang glider crash • Resting Place — Lankwitz Cemetery, Berlin • Known for — Successful gliding experiments; "Father of Aviation" • Education — College Mechanical Engineer Major • Occupation — Engineer • Children — 4 • Relatives — Gustav Lilienthal (brother)

Lilienthal was born on 23 May 1848 in Anklam, Pomerania Province, in the German kingdom of Prussia. His parents were Gustav and Caroline, née Pohle. He was baptised in the evangelical-lutheran St. Nicholas church and confirmed in St. Mary's church in Anklam. Lilienthal's middle-class parents had eight children, but only three survived infancy: Otto, Gustav, and Marie. The brothers worked together all their lives on technical, social, and cultural projects. Lilienthal attended grammar school and studied the flight of birds with his brother Gustav (1849–1933). 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. He later attended the Technische Hochschule in Berlin (now Technische Universität Berlin). In 1867, Lilienthal began experiments in earnest on the force of air, but interrupted the work to serve in the Franco-Prussian War. Returning to civilian life, he was a staff engineer with several engineering companies and received his first patent, for a mining machine. He founded his own company to make boilers and steam engines. On 6 June 1878, Lilienthal married Agnes Fischer, daughter of a deputy. Music brought them together; she was trained in piano and voice while Lilienthal played the French horn and had a good tenor voice. After marriage, they took up residence in Berlin and had four children: Otto, Anna, Fritz, and Frida. Lilienthal published his famous book Birdflight as the Basis of Aviation in 1889.

• Illustration — Mechanics of white stork flight in his Der Vogelflug als Grundlage der Fliegekunst (1889) Lilienthal's greatest contribution was in the development of heavier-than-air flight. He made his flights from an artificial hill he built near Berlin and from natural hills, especially in the Rhinow region. A U.S. patent filed in 1894 by Lilienthal directed pilots to grip the "bar" for carrying and flying the hang glider. The A-frame of Percy Pilcher and Lilienthal echoes in today's control frame for hang gliders and ultralight aircraft. Working in conjunction with his brother Gustav, Lilienthal made over 2,000 flights in gliders of his design starting in 1891 with his first glider version, the Derwitzer Glider, until his death in a gliding crash in 1896. His total flying time was five hours. • Illustration — Lilienthal in mid-flight, Berlin c. 1895 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. This is the site of man's first flight. Later he made his flight attempts on an artificial hill near Berlin and above all in the Rhinow Hills. In 1891 Lilienthal succeeded with jumps and flights covering a distance of about 25 m. He could use the updraft of a 10 m/s wind against a hill to remain stationary with respect to the ground, shouting to a photographer on the ground to manoeuvre into the best position for a photo. In 1893, in the Rhinow Hills, he was able to achieve flight distances as long as 250 m. This record remained unbeaten for him or anyone else at the time of his death. Lilienthal did research in accurately describing the flight of birds, especially storks, and used polar diagrams for describing the aerodynamics of their wings. He made many experiments in an attempt to gather reliable aeronautical data.

• Illustration — Models of his gliders • Illustration — Restored 1894 glider displayed at the National Air and Space Museum in Washington, D.C. It is one of five surviving Lilienthal gliders in the world. • Illustration — 1893 patent filing showing bird-wing design for a glider During his short flying career, Lilienthal developed a dozen models of monoplanes, wing flapping aircraft and two biplanes. His gliders were carefully designed to distribute weight as evenly as possible to ensure a stable flight. Lilienthal controlled them by changing the center of gravity by shifting his body, much like modern hang gliders. They were difficult to manoeuvre and had a tendency to pitch down, from which it was difficult to recover. One reason for this was that he held the glider by his shoulders, rather than hanging from it like a modern hang glider. Only his legs and lower body could be moved, which limited the amount of weight shift he could achieve. Lilienthal made many attempts to improve stability with varying degrees of success. These included making a biplane which halved the wing span for a given wing area, and by having a hinged tailplane that could move upwards to make the flare at the end of a flight easier. He speculated that flapping wings of birds might be necessary and had begun work on such a powered aircraft. • Aircraft produced by Otto Lilienthal • Name — Date — Wing — Glider — Notes • Span (ft) — Area (sq ft) — Max. length (ft) — Length (ft) — Weight (kg) • Derwitzer Glider — 1891 — 25 (later 18) — 108 (later 84) — 6.6 — 12.8 — 18 — Wing curvature: 1/10 of length. • Südende Glider — 1892 — 31 — 158 — 8.2 — 3.3 — 24 — Wing curvature: 1/20 of length. • Maihöhe Rhinow Glider — 1893 — 22 or 23 — 150 — 8.2 — 14.3 — 20 • Small Ornithopter — 1893–1896 — 22 — 129 — 8.2 — 5.5 — Weight with CO2 cylinder: 10 kg. • Normal soaring apparatus — 1894 — 22–23 — 140–146 — 7.9 / 8.2 — 16.1 – 17.4 — 20 — At least nine gliders sold. Original gliders or fragments are preserved in museums in London, Moscow, Munich and Washington. • Sturmflügelmodell — 1894 — 20 — 104 — 6.6 — 14.8 — Original can be seen at the Technisches Museum Wien. • Experimental Monoplane "Vorflügelapparat" — 1895 — 29 — 204 — 9.8 — 18.4 • Small Biplane — 1895 — 19.7 / 17.1 — 104 / 105 — 7.2 / 6.9 — 15.7 • Large Biplane — 1895 — 21.6 / 20.7 — 146 / 112 — 7.5 / 7.5 — 16.1 • Big Ornithopter — 1896 — 27.9 — 188 — 8.2 — 17.4 • Illustration — The unveiling ceremony of the new monument in Berlin. Gustav (left) and Paul Baylich, August 1932 While his lifelong pursuit was flight, Lilienthal was also an inventor and devised a small engine that worked on a system of tubular boilers. His engine was much safer than the other small engines of the time. This invention gave him the financial freedom to focus on aviation. His brother Gustav (1849–1933) was living in Australia at the time, and Lilienthal did not engage in aviation experiments until his brother's return in 1885. There are 25 known Lilienthal patents.

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. In 1892, Lilienthal's training area was a hill formation called "Maihöhe" in Steglitz, Berlin. He built a 4 m high shed, in the shape of a tower, on top of it. This way, he obtained a "jumping off" place 10 m high. The shed served also for storing his apparatus. In 1893, Lilienthal also started to perform gliding attempts in the "Rhinower Berge", at the "Hauptmannsberg" near to Rhinow and later, in 1896, at the "Gollenberg" near Stölln. In 1894, Lilienthal built an artificial conical hill near his home in Lichterfelde, called Fliegeberg (lit. flight hill). It allowed him to launch his gliders into the wind no matter which direction it was coming from. The hill was 15 m high. There was a regular crowd of people that were interested in seeing his gliding experiments.

Reports of Lilienthal's flights spread in Germany and elsewhere, with photographs appearing in scientific and popular publications. Among those who photographed him were pioneers such as Ottomar Anschütz and American physicist Robert Williams Wood. He soon became known as the "father of flight" as he had successfully controlled a heavier-than-air aircraft in sustained flight. Lilienthal was a member of the Verein zur Förderung der Luftschifffahrt, and regularly detailed his experiences in articles in its journal, the Zeitschrift für Luftschifffahrt und Physik der Atmosphäre, and in the popular weekly publication Prometheus. These were translated in the United States, France and Russia. 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. Zhukovsky wrote that Lilienthal's flying machine was the most important invention in the aviation field. Lilienthal corresponded with many people, among them Octave Chanute, James Means, Alois Wolfmüller and other flight pioneers.

On 9 August 1896, Lilienthal went, as on previous weekends, to the Rhinow Hills. The day was very sunny and not too hot (about 20 °C, or 68 °F). The first flights were successful, reaching a distance of 250 m in his normal glider. During the fourth flight Lilienthal's glider pitched upward and then headed down quickly. (It is believed that his glider stalled.) 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. His attempts failed and he fell from a height of about 15 m, while still in the glider. Paul Beylich, Lilienthal's glider mechanic, transported him by horse-drawn carriage to Stölln, where he was examined by a physician. Lilienthal had a fracture of the third cervical vertebra and soon became unconscious. Later that day he was transported in a cargo train to Lehrter train station in Berlin, and the next morning to the clinic of Ernst von Bergmann, one of the most famous and successful surgeons in Europe at the time. Lilienthal died there a few hours later (about 36 hours after the crash). There are differing accounts of Lilienthal's last words. A popular account, inscribed on his tombstone, is "Opfer müssen gebracht werden!" ("Sacrifices must be made!"). The director of the Otto Lilienthal Museum doubts that these were his last words. Otto Lilienthal was buried at Lankwitz public cemetery in Berlin. Guinness World Records recognizes Otto Lilienthal as the first person recorded to be fatally injured in a glider accident.

• Lilienthal was featured on a commemorative postmark in Berlin in 1953. • Lilienthal plays a major part (in absentia) in Theodora Goss's short story "The Wings of Meister Wilhelm," nominated for a World Fantasy Award and published in her anthology In the Forest of Forgetting. • A Lilienthal glider serves as a major plot element in Paul Gazis's Webserial "The Airship Flying Cloud, R-505". • "Lilienthals Traum" ("Lilienthal's Dream") is a song by Reinhard Mey that charts Lilienthal's flights and death. • "Lilienthal Berlin" is a German watch brand named after Otto Lilienthal

Lilienthal was regularly joined by photographers at his request. Most of them are well known, like Ottomar Anschütz. Lilienthal also took his own photographs of his flying machines after 1891. There are at least 145 known photographs documenting his test flights, some of excellent quality. All of them are available online at the Otto Lilienthal Museum website. The only negatives, preserved in the Deutsches Museum in Munich, were destroyed during World War II. • Illustration — Flight attempt of Lilienthal on the Derwitzer Glider, Derwitz, 1891 • Illustration — Lilienthal preparing for a Small Ornithopter flight, 16 August 1894 • Illustration — Vorflügelapparat, 29 May 1895 • Illustration — Normal soaring apparatus with the enlarged tail, 29 June 1895