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Eiffel
1903 Drop Test Machine and 1912 Wind Tunnel
Aérodynamique
Eiffel
Auteuil, Paris
 Late
in life, the renowned structural engineer Gustave Eiffel (1832-1923)
embarked on aeronautical research. Reliable data and repeatable
research methods were rare in the early 1900s, but Eiffel brought
an engineer's discipline to the field. In the process, he produced
the most accurate aeronautical data of the time, confirmed a long-held
theory about fluid flow that had never been unequivocally proven,
and established a laboratory that became a model for future practice.
In
1903, Eiffel built a device to test the drag on various bodies by
dropping them along a vertical cable hung from the second level
the tower that bears his name. He built a machine that accurately
measured drag during the fall and recorded it on a chart within
the machine. He tested about 40 shapes this way over the next three
years.
Wanting
longer test times, Eiffel built a wind tunnel next to the tower
(to use power from its generator) in 1909. In it he tested many
of the same shapes he had dropped, confirming the theory that air
moving around a stationary body produces the same drag as the body
moving through still air. This tunnel also tested models of entire
airplanes for the first time.
 Eiffel
expanded his research considerably when he opened his Auteuil laboratory
in 1912. It featured two wind tunnels that utilized a common test
chamber. Eiffel's test chamber allowed either jet of air to flow
across the closed room and past a test object without interference
from sidewalls, improving accuracy over earlier designs. Flared
inlet and outlet ducts improved the efficiency of these tunnels
and minimized their power requirement. These two features were adopted
in many later wind tunnels. The smaller tunnel was dismantled in
1933, but the larger one remains, making Auteuil the oldest surviving
aeronautical laboratory with its original wind tunnel intact.
The
tunnel was donated to the French government (Services Techniques
de l'Aéronautique) in 1920 when Eiffel was 88 years old.
It has been operated without interruption since its inauguration
and continues to be used for testing airplanes, buildings, and racing
(F1) cars. It has been designated a French National Monument. The
Eiffel drop test machine is exhibited in the lobby of Aérodynamique
Eiffel.
Gustave
Eiffel became an Honorary Member of ASME in 1886.
Designation
as a Historic Mechanical Engineering Landmark is scheduled for October
27, 2005.
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