Imagine rising off the ground and traveling through the sky with nothing but your own body and a pair of wings. This is only an imagined possibility, because people cannot fly the way birds do, so please never jump from a high place to try it. People have, however, invented a number of remarkable machines that come surprisingly close to that remarkable dream of flight. One of the simplest is the hang glider, a light aircraft with cloth wings and no engine. The pilot starts it by running off a hill. One glider pilot was Otto Lilienthal, a German engineer who made more than 2,000 glider flights in the 1890s.
Lilienthal studied the wings of birds to design his gliders, and he steered them by shifting his body weight, which is the same way hang glider pilots steer today. The Wright brothers got interested in flying after hearing about the glider flights of Lilienthal in the 1890s. Modern hang gliding is taught with considerable and deliberate care. Hang gliders are taught at licensed schools, where training begins on the ground and on small hills before higher flights. Rules in some places say the same thing in another way. As of November 2026, at Sleeping Bear Dunes National Lakeshore in the United States, hang glider and paragliding pilots must hold a current proficiency rating before they may launch.
A glider needs a hill or a tow to get going, but some aircraft are powered by the pilot alone. In 1979 a pilot pedaled the Gossamer Albatross, a human-powered airplane, across the English Channel, about 36 kilometers (22 miles) in 2 hours 49 minutes. The airplane was 93 feet 10 inches (28.6 meters) wide and weighed 70 pounds empty. It needed less than half a horsepower (373 watts) and flew at only about 10 to 15 miles per hour. Another pedal-powered airplane traveled considerably farther. In 1988 the human-powered airplane Daedalus flew about 115 kilometers (72 miles) across the sea from Crete to Santorini in Greece. It used bicycle pedals to turn a big, slow propeller through a chain drive, and it was built largely of carbon-fiber composite and Mylar. Daedalus has a wing spanning 112 feet, and the wing alone weighs just 52 pounds. The whole airplane weighed less than 70 pounds.
None of these machines flaps its wings like a bird, and flapping turns out to be a much harder engineering problem. A human's arm and chest muscles are not strong enough to flap wings big enough to lift a person. In August 2010 the Snowbird became the first human-powered flapping-wing aircraft reported to fly continuously. Its pilot, Todd Reichert, was towed up and then flew on his own power. The pilot estimated he could produce about 0.3 horsepower, roughly 220 watts. Although the Snowbird's wingspan is comparable to that of a Boeing 737, it weighs less than all the pillows on board a 737. A fixed wing is the easier path, because it can be built both long enough and light enough. By 2010 about 100 human-powered airplanes with fixed wings had flown. The Daedalus project's testing also helped bring about new technology for high-altitude, long-endurance aircraft, according to NASA.
Words to know
- glider: aircraft without engine
- horsepower: unit of power
- propeller: spinning blade
- wingspan: tip-to-tip width
- composite: mixed material
