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THE WRIGHT BROTHERS—AERO THEORETICIANS

THE WRIGHT BROTHERS went far beyond being bicycle builders because of their extraordinarily methodical approach to all of their activities.

Why, for example, did these Ohioans first fly at Kitty Hawk, North Carolina, more than 650 miles from their Dayton family home?

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The Wright family home, 7 Hawthorne Street, Dayton, Ohio. The bicycle parked out front is most appropriate.

It was only after intensive studies of U.S. Weather Bureau data that the brothers selected Kitty Hawk because of its reliable winds, important to their glider investigations that would lead to powered flight. What’s more, studies with a bicycle enhanced these investigations.

Early in their aeronautical activities, the Wrights researched the design work of Otto Lillienthal, German aviation pioneer revered as the Glider King. Lillienthal had perished in a glider crash in 1896, but he left a wealth of carefully documented data. The Aero Club of America Bulletin, September 1912, reported Wilbur Wright’s having said, “Of all the men who attacked the flying problem in the 19th century, Otto Lillienthal was easily the most important.”

However, performance of the Wrights’ gliders failed to correlate with Lillienthal design criteria, and this led the brothers to refine values for coefficients of lift and drag. To get data on this, they fashioned small wings and compared resulting lift and drag data to those of a flat plate. To move these experiments through the air, the Wrights adapted a device familiar to them both: a bicycle.

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The Wrights’ airfoil measurement bicycle. This and the following image from NASA.

The Wrights attached the two surfaces being compared to a bicycle wheel that was angled into the wind on the bicycle’s front fork. Pedaling the bike produced the wind. And resulting rotation of the test wheel gave a measurement of the wing’s lift and drag.

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The relation between lift and drag on the Wrights’ bicycle test wheel. See NASA’s Wright 1901 Bike Test for details.

The brothers’ experiments with their bicycle suggested that Lillienthal had been overestimating lift. However, they also sensed that wind velocity produced by pedaling a bicycle was all too variable. This led to their next invention, a wind tunnel.

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A replica of the Wrights’ 1901 wind tunnel, displayed at the National Museum of the U.S. Air Force, Wright-Patterson AFB, Dayton. These images and those following from the museum.

TunnelVanes

The blower fan was driven by an overhead belt, typical of the era. It produced wind speeds of 25 to 35 mph, higher and more reliable than that produced by the Wrights’ pedaling. The vanes smoothed turbulence of the air flow, giving a reproducible velocity unavailable to the bicycle test rig.

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A balance devised by the Wrights to measure lift of a test surface. A similar device measured drag.

The test airfoil was mounted on Wright-designed balances fitted toward the exit of the tunnel. The brothers read balance scale values for the various airfoils at different angles of attack through a glass port in the top of the tunnel. Aerodynamic tables derived from these tests were vital to success of the 1903 Wright Flyer’s airfoil as well as its propeller design.

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The exit end of the Wrights’ tunnel. The NASA site 1901 Wind Tunnel offers details as well as a downloadable wind tunnel simulation.

This replica of the Wright wind tunnel was constructed prior to World War II, under the supervision of Orville Wright.

Orville made his last flight as a pilot in 1918 in a 1911 Model B. For 28 years, he served with NACA, the National Advisory Committee for Aeronautics, which evolved into NASA. Dying of a heart attack in 1948 at age 76, Orville lived from aviation’s first hops to the dawn of supersonic flight.

His elder brother Wilbur had died in 1912 at age 45, diagnosed with typhoid fever. Their father, a bishop in the Church of the United Brethren, wrote of Wilbur, “A short life, full of consequences. An unfailing intellect, imperturbable temper, great self-reliance and as great modesty, seeing the right clearly, pursuing it steadfastly, he lived and died.”

Both brothers were aeronautical theoreticians of the highest order. ds

© Dennis Simanaitis, SimanaitisSays.com, 2016

One comment on “THE WRIGHT BROTHERS—AERO THEORETICIANS

  1. Bill Urban
    July 24, 2016

    Dennis, an enlightening lesson. I suspect that 95% of people asked would say they were two bicycle mechanics that only happened upon the correct design.

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