In the early years of the 20th century, we were awed by the rapid progress of aviation. From the Wright Brothers' first sustained and controlled flights in Ohio, to the first jet in only thirty-five years! The rapid progress was enabled by the simple but effective combination of a rotating propeller and fixed wings. As if to glorify the new invention, newsreel films mocked those who still pursued a flapping-wing approach. Perhaps these demonstrations were necessary in order to justify our having abandoned flapping wings. In any case, the many failures were so well publicized that it seemed even birds might fall from the sky.

Adalbert Schmid knew all about fixed wings. During the 1930s, he worked as an aircraft designer with the firm H&G Pause-Modellwerk. His 1939 "Mosquito" design was a two-seat, high-winged monoplane flying on 40 hp. Despite his airplane experience, Schmid believed flapping wings had the potential to revolutionize sport aviation.

Schmid began studying flapping-wing flight in 1919. By 1932 he had flown his first small ornithopters in free flight. His goal was to build a manned aircraft, so he then turned his attention to larger-scale propulsion tests on the ground. His muscle-powered flapping wings reportedly generated a thrust of 180 to 200 kg. While this figure is likely erroneous, given its unexpectedly high value and the difficulties of measuring an oscillating thrust value, for Schmid it seemed cause for taking the next step.

Schmid constructed an ornithopter, weighing 60 kilograms and having a wingspan of 12.6 meters. From the sides of the fuselage emerged smaller flapping wings, each 3.2 meters long. The flapping wings were arranged to move in a circular motion instead of straight up and down, perhaps imitating the upstroke wingspan reduction utilized by birds. Although some have objected to Schmid's combination of fixed and flapping wings, birds too have a substantial fixed lifting surface in the body and tail. It is only by the thrust of the flapping wings that these fixed surfaces are able to produce lift.

On the 26^th of June, 1942, Schmid's ornithopter flew a distance of 900 meters on the sheep pastures outside Munich. After being towed aloft, the ornithopter maintained its 20 meter starting height until the end. Although Schmid considered this flight a success, the capabilities of the aircraft were obviously limited by human muscle output. Our muscles can't produce very much power, and their maximum output can be maintained only for a short period of time.

The use of a tow launch calls into question what was accomplished that day. Some have pointed out that when an underpowered aircraft is launched at a speed higher than its stall speed, it can maintain a constant height for some distance as the initial speed is gradually lost. An ornithopter designed by Alexander Lippisch achieved a similar flight in 1929, covering a distance of about 250 to 300 meters. Considering the limited duration of human muscle output and the possible excess launch velocity, we don't have enough information to determine whether either ornithopter could have flown briefly on muscle power alone.

To resolve these issues, Schmid next installed an engine in the ornithopter. This provided far more power than what the pilot's muscles could furnish. With a 3 hp Sachs motorcycle engine, and presumably wheels added, the ornithopter was able to take off unassisted from the ground. It made a quiet 15-minute flight at about 60 kilometers per hour. Then a 6 hp engine was installed, increasing the speed to 80 kph. After these historic accomplishments, Schmid's work was interrupted by the war.

By 1947, however, Schmid had constructed a second ornithopter. This one, a modified Grunau-Baby IIa sailplane, was constructed with flapping outer wing sections. Using a 10 hp engine, this double-seater was capable of speeds estimated at 100 to 120 kilometers per hour. (If you know of any photographs of this later ornithopter, or if you have any other information, please send an e-mail using the appropriate link at the left side of the page.)

Schmid, an old man in 1950, lamented that his work would not be continued. Apparently his ornithopter was dismissed as not having any military value. Yet Schmid believed flapping-wing flight had some practical advantages. "Do we understand what it means," he wrote, "to start and be able to fly with 3 hp? At a distance of 100 km, to use no more than 1.5 liters of fuel?" Given the circumstances and timing of Schmid's endeavors, it is no surprise that his work was largely unrecognized. Aviation culture had been set against flapping wings. His country had been devastated by war, and there were more important concerns. Now, though, it's time to take notice of Schmid's accomplishments and further develop the potential of birdlike flight. We can fly by flapping wings!

1. Schmid, Adalbert. Weltluftfahrt, volume 1, issue 9, March 1950, page 195.
2. Lange, Bruno. Typenhandbuch der deutschen Luftfahrttechnik. Koblenz, 1986.
3. Herzog, Karl. Der Schwingenflug in der Natur und in der Technik. JF Schreiber Verlag, Mechanikus, January 1963.
4. Lippisch, Alexander. Man Powered Flight in 1929. Journal of the Royal Aeronautical Society. July 1960.