Lilienthal's two-surface glider of 1895 in which some of his highest and longest glides were made. This German engineer made hundreds of glides with various apparatuses employing birdlike wings.

Pioneers of Flight

Since the dawn of history the idea of human flight has intrigued mankind. As the influence of the Wrights' achievements will last far into the future, so will the contributions of aeronautical pioneers who probed the mysteries of flight before Wilbur and Orville solved the problem. The research of these imaginative pioneer investigators influenced the brothers. In studying those earlier works the Wrights found many points that interested them. The knowledge that other pioneers had shared their faith in the possibility of heavier-than-air flight helped their morale.

In the pioneers' direct line of descent from the Greek legend of Daedalus and Icarius to the Wrights is Leonardo da Vinci. Da Vinci drew some interesting sketches in the late 15th century, though a machine built from his drawings could not possibly have flown. The interest in England of Sir George Cayley influenced other men to undertake the problem.

A Frenchman, Alphonse Pénaud experimented with toy helicopters, using twisted rubber bands for motive power. It was a Pénaud toy helicopter, given to Wilbur and Orville by their father, that first stirred their childhood interest in flying. However, in Europe, most experimenters had turned from heavier-than-air machines to lighter-than-air dirigible balloons by the time the brothers took up the problem of heavier-than-air flight. The American-born Sir Hiram Maxim, after spending $100,000, had abandoned his work; the machine built by Clement Ader, at the expense of the French Government, had been a failure. None of the early experimenters attained sufficient knowledge of the aerodynamic principles involved to be able to design a successful powered machine capable of free, controlled, and sustained flight.

Otto Lilienthal (1848—96).

Only a few of the general public could distinguish between a heavier-than-air powered flying machine and a lighter-than-air gas bag equipped with propellers. Few knew that the problem of powered flight was not to fill a balloon with gas or hot air and float in it, or to glide in a complicated kite against air currents. Many among those who realized the obstacles to heavier-than-air flight in a powered machine believed it was as impossible as perpetual motion.

Wilbur and Orville acknowledged Otto Lilienthal, a famous German pioneer in aviation, as their greatest inspiration. Recognized as the father of gliding, Lilienthal made hundreds of glides with various apparatuses employing birdlike wings. First to explain scientifically why curved surfaces in a flying machine are superior to flat surfaces, Lilienthal's work on wing surfaces and air pressure proved valuable to the Wrights. Interested in scientific affairs, the brothers read with fascination and excitement, reports in 1895 of gliding flights by Lilienthal. But the art of gliding was neither a game nor child's play for aviation's pioneers. Lilienthal crashed and died as a result of a glider accident in 1896. Reading of his death, the Wrights wondered if they could go on from where he had left off.

Courtesy, Smithsonian Institution

Samuel Pierpont Langley (1834—1906).

Eventually the Wrights were ready to begin "a systematic study of the subject in preparation for practical work," and hoped to make contributions "to help on the future worker who will attain final success." Searching for, but finding little material on attempts to fly in the Dayton Public Library, Wilbur wrote, in May 1899, to the Smithsonian Institution in Washington seeking information about publications to read on aeronautics. The list of books and articles suggested by the Smithsonian included works by Dr. Samuel P. Langley who later became its director and secretary. The brothers were encouraged by seeing that a man of Langley's scientific standing believed in the possibility of flight at a time when few people did. Langley had been making aeronautical studies and experiments and succeeded in building power-driven models that flew. Later he built and attempted to fly a full-size, man-carrying powered machine; but in this he failed.

Octave Chanute (1832—1910).

When a model flies, it does not necessarily follow that a full-size machine of the same design will also fly. As boys Wilbur and Orville had built model Pénaud helicopters that flew, but even the Wrights could not later have built a successful man-carrying machine by merely following Pénaud's same general design. The difficulty is—as early experimenters with model machines unhappily discovered—that when the linear measurement of a model is doubled it needs about eight times the power to make it fly.

Among the sources suggested by the Smithsonian was Octave Chanute's Progress in Flying Machines. Chanute, a successful construction engineer living in Chicago, had directed experiments with gliders of his own design. A longtime encouraging friend and adviser to the Wrights, Chanute made an exhaustive study of the history of aeronautics.