Читать книгу The Rise of the Flying Machine - Hugo Byttebier - Страница 31

Otto Lilienthal

In 1889 a book was published by an eager German enthusiast. The author was Otto Lilienthal, born in 1848, and he heralded the entry of Germany into the field of aviation. Lilienthal, by his experiments with full-size man-carrying gliders up to his fatal final flight in 1896, was an early inductee into the International Air & Space Hall of Fame.

Germany had not at that time contributed much to the advancement of the science of flight, though an exception has to be made for Karl Friedrich Meerwein a century earlier. In 1781 he published an essay with the optimistic title Why should Man not be Born with the Possibility to achieve Flight? A prophetic figure, Meerwein, even before Cayley, had foreseen the possibility that man could emulate birds by means of a machine, as his intelligence and his status as Lord of creation entitled him.

“Why should a man be too heavy for flight?” asked Meerwein. He thought that it would only be necessary to construct a machine with wings large enough to carry his weight aloft. In order to achieve this project Meerwein suggested the use of two flat wings, pointed at the tips and with a high aspect ratio, and which could carry about 2 lbs/sq ft. This turned out not to be far removed from the realities of aerodynamics. The experiment required a courageous volunteer to be attached to the wing in a horizontal position and to flap his arms up and down, which Meerwein perceived as solving the problem. No consideration was given to taking-off or landing, and Meerwein was not very sure about man’s ability to move the wings with his musclepower alone, adding the sound advice that the first attempts should be made over water. He went so far as to build a glider himself, although he achieved no success. In 1784 he published a second pamphlet with the premonitory title: The Art of Flying after the Manner of the Birds.

A few years later Jacob Degen, another German fascinated by mechanics and a clockmaker by profession, built an ingenious machine shaped like a double umbrella which was moved by the force of his legs and arms. Degen was never able to achieve free flight, although a newspaper’s claim that he had done so inspired Sir George Cayley to write his famous 1809-1810 triple paper.

The title of Lilienthal’s book, Bird Flight as the Foundation of the Art of Flying (Der Vogelflug als Grundlage der Fliegekunst) was reminiscent of Meerwein’s 1784 essay The art of flying like birds (Die Kunst zu fliegen nach Art der Vögel).

In his book Lilienthal expounded his theory about flight and the means of achieving it, resulting from years of research and observation of live birds, of experiments with small models and of theoretical considerations. He also wrote about his visions of a Utopian future and included some poems exalting the ideal of flight and expressing the hope that man would soon emulate birds. His ideal was soaring flight as he had seen storks achieve in his native Pomerania.

The principal lesson Lilienthal had learned from the great soaring birds was the use of curved wings and he was convinced that this discovery, which he made in 1873, would open the way to the skies. He was not acquainted with the writings of Phillips and Goupil and he may be excused for thinking that his discovery was original because, as late as 1892, Hureau de Villeneuve, in an appraisal of Lilienthal’s book, was still convinced of the superiority of flat wings.

The book caused quite a stir and was eventually translated into English, but Lilienthal achieved fame because he did not limit himself to theoretical speculations, being one of the first to start practical experiments. The year after the publication of his book he built a full-sized glider that would carry him aloft and allow him to fly, in the manner that had been proposed by de La Landelle in his article about the “dirigible parachute” in 1884.

Lilienthal’s original idea was to fly by means of flapping wings, but as a preliminary he decided to try a fixed-wing soaring machine that was easier to build and simpler to handle. He thereby became the originator of the modern sport of hang-gliding.

During most of his experiments Otto Lilienthal was assisted by his younger brother Gustav and the pair prefigured the activities of the equally famous Wright brothers in the US. In both cases the older brother was the driving force who gave his life for his ideal and the younger brother devoted the remaining years of his life to the vindication of their vision.