Otto Lilienthal

Lilienthal was born on 23 May 1848 in Anklam, Pomerania Province, German kingdom of Prussia. According to his baptism certificate,[4] his parents were Gustav and Caroline née Pohle. They belonged to the St. Nikolai evangelical church community in Anklam, where he later attended grammar school, and where he eventually studied the flight of birds with his brother Gustav (1849–1933).[5] Fascinated by the idea of manned flight, Lilienthal and his brother made strap-on wings, but failed in their attempts to fly. He then attended the regional technical school in Potsdam for two years and trained at the Schwarzkopf Company before becoming a professional design engineer. He would later attend the Royal Technical Academy in Berlin.

In 1867, Lilienthal began experiments on the force of air in earnest, interrupted when he served in the Franco-Prussian War. As a staff engineer in various engineering companies, Lilienthal received his first patent for a mining machine. Five years later he founded his own company to make boilers and steam engines.[6] Lilienthal published his famous book Birdflight as the Basis of Aviation in 1889.

Lilienthal was born to middle-class parents. They had eight children, but only three of them survived infancy: Otto, Gustav, and Marie.[7] The brothers worked together all their lives on technical, social, and cultural projects.

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.[8] After marriage, they took up residence in Berlin and had four children: Otto, Anna, Fritz, and Frida.[1]

Mechanics of white stork flight in his Der Vogelflug als Grundlage der Fliegekunst (1889)

Lilienthal in mid-flight, c. 1895

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.

The filing of a U.S. Patent in 1894 by Lilienthal directed pilots to grip the "bar" for carrying and flying the hang glider.[9] 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, until his death in a gliding crash in 1896. His total flying time was five hours.[10]

At the beginning, in 1891, Lilienthal succeeded with jumps and flights covering a distance of about 25 metres (82 ft). 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 metres (820 ft). This record remained unbeaten for him or anyone else at the time of his death.[10]

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.

Projects

Models of his gliders

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.

During his short flying career, Lilienthal developed a dozen models of monoplanes, wing flapping aircraft and two biplanes.[11] 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. However they were difficult to maneuvre 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[12]
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.
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

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.[13] 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.[14]

There are 25 known Lilienthal patents.[15]

Reports of Lilienthal's flights spread in Germany and elsewhere, with photographs appearing in scientific and popular publications.[23] 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 metres (820 ft) in his normal glider. During the fourth flight Lilienthal's glide pitched forward heading down quickly. 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 metres (49 ft), while still in the glider.[24]

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.[25] Otto Lilienthal was buried at Lankwitz public cemetery in Berlin.

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. However, they abandoned his aeronautical data after two seasons of gliding and began using their own wind tunnel data.[26]

Bronze plaque medal of Stölln, where Lilienthal had his fatal accident

The Lilienthal monument, Berlin 2006

Of all the men who attacked the flying problem in the 19th century, Otto Lilienthal was easily the most important. ... 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.

— Wilbur Wright[27]

Berlin's busiest airport, Berlin Tegel "Otto Lilienthal" Airport, is named after him.

In September 1909, Orville Wright was in Germany making demonstration flights at Tempelhof aerodrome. He paid a call to Lilienthal's widow and, on behalf of himself and Wilbur, paid tribute to Lilienthal for his influence on aviation and on their own initial experiments in 1899.

In 1972, Lilienthal was inducted into the International Air & Space Hall of Fame.[28]

In 2013, American aviation magazine Flying ranked Lilienthal No. 19 on their list of the "51 Heroes of Aviation".[29]

• In the music video for "Losing My Religion" by R.E.M., workers build an ornithopter named "Otto" in honor of Lilienthal.[30]
• 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 fictional characterization of Lilienthal was resurrected as an evil clone in the Japanese Read or Die (2001) novels, anime, and manga.
• A Lilienthal glider serves as a major plot element in Paul Gazis's Webserial "The Airship Flying Cloud, R-505".[31]
• "Lilienthals Traum" ("Lilienthal's Dream") is a song by Reinhard Mey that charts Lilienthal's flights and death.[32]

Lilienthal was regularly joined by photographers at his request. Most of them are well known, like Ottomar Anschütz. Lilienthal was also constantly taking his own photographs of his flying machines after 1891.[33] 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.[23]

• Lilienthal Gliding Medal
• Otto Lilienthal Museum
• Aviation history
• Albrecht Berblinger
• Abbas Ibn Firnas
• George Cayley
• Jean-Marie Le Bris
• John Joseph Montgomery
• Percy Pilcher
• German inventors and discoverers

• Biography / family tree of Otto Lilienthal
• Lilienthal's appendix from Chanute's book Progress in Flying Machines 1893.
• Movies and simulations
• "Lilienthal in England" a 1967 Flight article
• Otto Lilienthal at Answers.com
• Otto Lilienthal (1889) Der Vogelflug als Grundlage der Fliegekunst - digital facsimile from Linda Hall Library
• Otto Lilienthal (1911) Birdflight as the basis of aviation, compiled from the results of numerous experiments made by O. and G. Lilienthal - digital facsimile from Linda Hall Library
• Newspaper clippings about Otto Lilienthal in the 20th Century Press Archives of the ZBW