Otto Lilienthal: First
German engineer Otto Lilienthal was the first man to launch
himself into the air, fly, and land safely. He also was an
important source of inspiration and information for the Wright
brothers in the next decade.
born in Pomerania, Germany in 1848. Even as a teenager, he was
interested in flight, and with his brother Gustav, in 1867 built a
frail contraption of thin birch veneer. They intended to strap
themselves to the pair of 6-1/2-foot (two-meter) wings, run down a
hill while flapping their arms, and take off into the air. Their
experiment was unsuccessful, but they persevered and built two
more winged vehicles. These failed too, but Otto remained
committed to the idea of human flight. He studied at Potsdam and
Berlin and received a degree in mechanical engineering from Berlin
University in 1870. After an interruption to serve in the
Franco-Prussian War of 1870-71, he continued with his aeronautical
After the war,
Gustav became an architect and left Otto to open his own factory
in Berlin to manufacture boilers and steam engines. Otto resisted
the urge to plunge ahead with building flying machines, even
though the pull was strong. He first devoted himself to studying
the principles of aerodynamics and analyzed how birds flew before
he attempted to apply those principles to a structure.
experimenting with ornithopters, in 1889 he published a book on
the flight of birds that outlined his theories and which became
one of the classics of aviation. In Der Vogelflug als Grundlage
der Fliegekunst (Bird Flight as the Basis of Aviation), he
examined in detail the types and structure of bird wings, the
method and aerodynamics of bird flight, and the application of the
data he gathered especially that dealing with wing area and lift
to the problem of human flight. He described how birds propelled
themselves by the twisting, or airscrew, action of their outer
primary feathers. Lilienthal tabulated the amount of air
resistance offered to a bird's wing with various degrees of camber
and determined that the curve was necessary to flight because it
offered more resistance than a flat surface.
He built his
first glider in 1891. Before his death in 1896, he had built
eighteen models—fifteen monoplanes and three biplanes. He had
also taken more than 2,000 glider flights.
Lilienthal biplane glider
in flight, 1895.
Shows structure of the glider with the double sailing surface.
first glider, the 1891 Derwitzer Glider, was constructed of rods
of peeled willow covered by highly stretched strong cotton fabric.
He used a springboard in his garden at first at a height of a
little over three feet (one meter), then gradually increasing to
8.2 feet (2.5 meters) to launch himself into the air. His first
flights took him only a few feet but gradually the distance
lengthened until he could glide almost 80 feet (24 meters). The
glider originally had a wingspan of 25 feet (7.6 meters). During
the course of the experiments, he reduced its span to 18 feet (5.5
feet). As in all his gliders, he controlled the glider's direction
by shifting his weight a task that required considerable strength.
In 1892, he
constructed a more sophisticated glider with fabric that covered
both sides of the wings. This glider had a wingspan of 31 feet
(9.4 meters). He could fly it up to a distance of 270 feet (82.3
Lilienthal's "Jumping Off"
place from the front.
Lilienthal realized he needed more flying space. In 1894, he built
an artificial hill topped with an earth-covered shed for storing
his machines. He would run down his hill and leap into the face of
the wind, reportedly gliding more than 150 feet (45.7 meters). He
could also launch himself from the top of the 13-foot (4-meter)
gliding experiments, 1892.
From there, he
progressed to his Maih-he-Rhinow-Glider. He called this a
convertible flight apparatus, and Lilienthal received a patent
for its design. It had a bat-like construction and when collapsed,
measured 6.6 x 10.5 x 1.6 feet (2 x 3.2 x 0.5 meters). He could
change the wing profile by inserting different ribs.
still more space for his experiments as well as a location with
height and strong, steady winds. He began flying in the Rhinower
Hills, about six miles northwest of Berlin. Launching himself from
the hillside, he glided up to 1,150 feet (350 meters).
glides from the top of his hill.
others before him, Lilienthal never quite abandoned the idea that
flapping wings was the key to motion. In 1893 and again in 1896,
he built gliders with flapping wings in the ornithopter fashion.
Each machine had a lightweight carbonic acid engine that produced
about two horsepower (1.5 kilowatts). The engine was supposed to
make the wing tips flap up and down and move the aircraft forward.
Neither model was successful.
Lilienthal's 1893 glider.
From 1894 until
his death in 1896, Lilienthal constructed his ôstandardö glider.
These monoplanes were highly successful, and he sold or gave
several of them to clients. They had cambered wings with radiating
ribs that could be folded for transport and a fixed rear fin and
tailplane that freely hinged upward. With these machines,
Lilienthal could glide from 300 feet (91.4 meters) to more than
750 feet (228.6 meters). His design incorporated a prellbugel,
or rebound bow. This was a flexible willow hoop fitted in front of
the pilot that would reduce the impact in case of a crash. The
apparatus saved Lilienthal's life during one flight when the
glider stalled and nose-dived toward the earth from more than 60
feet (18.3 meters) above ground.
"jumping off" place.
continued testing and enhancing his standard glider. In 1895, he
tested unsuccessfully a leading-edge flap device that was intended
to counteract air pressure on the cambered upper surfaces of the
wings as well as steering air-brakes and a form of wing-warping.
At the time of his death, he was developing a body-harness
elevator control to supplement his body movements. He became a
skilled pilot and could ride the wind and handle his craft
skilfully. During this time, he also was visited by several
aerodynamic experts, including Samuel Langley, secretary of the
Smithsonian Institution in Washington, D.C., and N.J. Shukowsky,
an aerodynamics expert from Moscow.
Lilienthal's gliders had one major fault. They had no means of
control other than the motions of the pilot who had to contort
himself and exercise considerable strength to affect the direction
and stability of the glider. To fly the glider, Lilienthal had to
crawl under the craft, position his arms in a set of cuffs, grasp
a bar near the front edge of the wings, and run down a slope. Once
aloft, his legs dangled below him. His only way to balance the
craft was to shift his weight. He moved the lower half of his body
in the direction he wished to go, which changed the centre of
gravity. By shifting his weight, he reacted to the movement of the
glider rather than directing it.
Lilienthal shifts his body
to move the glider to the right.
Shows how Lilienthal
changed the centre of gravity and particularly the position of
his legs to the left in order to press down the left wing. From
"Practical Experiments for the Development of Human Flight."
On August 9,
1896, the glider he was piloting stalled and went into a nosedive.
It had no prellbugel to protect him, and he died the next day of a
broken spine. His last words were Sacrifices must be made.
Lilienthal piloting his
Lilienthal soars through
designs had flaws, Lilienthal had an immense influence on
aviation. His writings were translated and distributed worldwide,
and the photographs that documented his flights visually proved
that a human could launch himself into the air and stay aloft. He
demonstrated the importance of identifying the principles that
governed an experiment before proceeding, and his meticulous
documentation of his research provided guidance for those that
came after him.