We all know the story of the two bicycle-shop brothers from Ohio who built and flew the first successful heavier-than-air aircraft from the dunes of North Carolina on December 17, 1903. From our vantage point one century later, though, many of us fail to appreciate the meticulous work that led to the dawn of aviation … much of it done not by the Wrights themselves, but those who had come before.
GLIDING 101: OTTO LILIENTHAL
Aware that the weight-to-power ratio of existing engines was prohibiting heavier-than-air flight but still wanting to further development of airplanes, several scientific experimenters turned their attention to gliding flight.
The glider pilots took aeronautical theory and turned it into practical flying experience, most notably developing the engineering of light, sturdy airframes, and the rudiments of aircraft control that were vital to future powered flight.
Between 1866 and 1889 German Otto Lilienthal tested numerous cambered surfaces with a Caley-like (see last week’s article) rotating-arm testing device that measured up to 23 feet long. His studies of wing camber and the resulting lift were flawed, however, leading him to believe that powered flight would be forever impossible.
Yet Lilienthal went on to study ornithoper (human-powered, birdlike flapping wing) design, and published one of the classics on early aerodynamics, Bird Flight as the Basis of Aviation, in 1889. He followed with a highly successful series of gliding flights, becoming in 1891 the first person to successfully launch, fly and land safely a heavier-than air aircraft.
Lilienthal made over 2000 gliding flights between 1891 and 1896, observed by many and well documented by the emerging photography of the day. His foot-launched gliders were lightweight, strong and very stable. Control was obtained through fixed rudder surfaces, and “weight shift” technique, similar to today’s hang gliders.
Lilienthal was able to make glides for up to 1150 feet from his starting point. Aerodynamics, however, were still far from completely understood. Otto Lilienthal stalled his glider on August 9, 1896, suffering a broken spine in the resulting crash. He died the next day, uttering his famous last words: “Sacrifices must be made.” You are the beneficiary of those sacrifices.
AVIATION’S MENTOR — OCTAVE CHANUTE
Naturalized American Octave Chanute had already earned engineering fame by designing the first railroad bridge across the Missouri River, at Kansas City, Missouri, before turning his attention to the dream of flight.
During an 1875 tour of Europe he discovered the great progress in model airplane flight being made there, writing about it in American engineering journals and in 1894 his classic Progress in Flying Machines, the first single volume to document aeronautical research. Using analytic methods he learned as an engineer, he then set out to advance the art himself. At age 54 he retired from engineering and began flying experiments full-time.
Flying Lilienthal-style gliders in the 1890s, he determined that weight-shift was not the answer to aircraft control. Instead, he sought what he called “automatic stability.” Chanute’s 1897 glider Katydid employed numerous wings that could be moved and adjusted to facilitate experimentation with stability. In Katydid Chanute completed more than 200 successful flights from the dunes of Lake Michigan.
Teaming with an engineer by the name of Herring and harking back to his bridge-building past, Chanute then built and flew trussed biplane designs, cross-braced with wires to relieve stress loads. His biplane gliders were the direct precursors to the Wright Brothers’ first aircraft. Although Chanute sought “automatic stability” for aircraft control, he never found it. All his gliders were controlled by Lilienthal-style weight-shift techniques.
Perhaps more importantly, Chanute mentored others trying to enter the world of flight. He helped expatriate Russian William Paul Butusov design the Albatros, which reportedly glided at Butusov’s home in Kentucky around 1898. Chanute’s co-designer Herring meanwhile affixed a small engine driving a tractor and pusher propellers to his glider, reportedly making short, powered flights, with little control, in 1897.
More successful was Chanute disciple William Avery‘s 80 gliding demonstrations at the St. Louis Exposition in 1904. For these flights, a winch attached to a rolling dolly would haul Avery and his glider until they were high enough to release and glide — similar to later sailplane launching techniques and flat land hang-glider launches.
Most notably, however, Chanute corresponded with two new faces on the gliding scene, brothers Wilbur and Orville Wright of Dayton, Ohio.
Rightly so, this year we celebrate the centennial of the Wright Brothers’ crowing achievement, heavier-than-air flight. As the Wrights themselves wrote, though, they were not working in an information vacuum. Instead, they (like us) were the recipients of knowledge that came from the minds, and lives, of those who had come before.
Next time: More powered experiments; and the Wrights learn to fly