The Rise of the Flying Machine. Hugo Byttebier

Although it was an interesting theory it was not the correct one.

      A similar theory was offered by Zahm in a paper that sought to explain the problem by the existence of windgusts, whilst the Frenchman Bretonnière ventured the theory that the heat of the sun was the moving force and in this he was much nearer the mark.

      Lilienthal contributed with parts of an article about his glides of 1892 and the Austrian Wilhelm Kress was also at hand with a theory of his own. Additionally, one of the oldest theorists of fixed-wing flight, Charles de Louvrié, contributed a paper about “The Theory of Soaring Flight”.

      De Louvrié, who had written his first paper about aeroplane-type flight nearly thirty years before, again hit the mark by indicating the ascending wind as the principal cause of the horizontal flightpath of the great soaring birds and he added the keen observation that: “Such a thing as a horizontal wind hardly exists, we need but to watch the whirling of dry leaves in Autumn”. De Louvrié had proposed fixed-wing flight at a time when very few people believed in it and his paper at Chanute’s Congress was his swansong before his death the following year.

      Another pioneer who was experimenting with gliders was J. J. Montgomery, who discussed various theories on soaring flight; and from Britain there was an article submitted by B. F. Baden Powell entitled “The Action of a Bird’s Wing”.

      The most interesting papers, however, were presented by those who were busy working with kites and who necessarily were confronted by the overriding quest for stability. The most important of these papers was read by Lawrence Hargrave. This Australian researcher had progressed from flapping-wing to fixed-wing aeroplane models, and in 1892 had started a series of experiments on supporting surfaces to find out how lift and stability could be obtained with the least possible expenditure of power.

      He experimented with a series of kites until he hit on the famous box kite, which was an inherently stable construction. Hargrave thereupon committed himself enthusiastically to the achievement of inherent stability. In the biplane box kite construction Hargrave turned to Wenham for inspiration, and he explained that he had not found additional support in the use of a second superposed wing but had accepted the results obtained by Langley in 1889 on an experimental biplane construction.

      So, it may be said that the biplane evolved from the general theory of superposed planes proposed by Wenham in 1866 and from the experiments made by Langley in 1889. But here also the origins can be traced back to Cayley who, horrified at the extension of the monoplane wing in Henson’s project of 1843, proposed a triplane construction in the following terms: “to compact it into the form of a three decker, each deck being 8 or 10 ft from the other to give free room for the passage of air between them”.

      Hargrave declared that the tandem-wing construction he used was more stable when separated by an interval than when conjoined. As he invariably gave everybody his due, in his paper he referred to a patent of 1871 by Danjard and the building of the first tandem-wing aeroplane model by D. S. Brown in 1874.

      The box kite was more wasteful of power than the Pénaud construction because of the additional drag caused by a second cell at the rear and by the vertical curtains at the sides. Hargrave also experimented with flat and curved wing sections and he discovered that curved wings pulled twice as much as flat ones.

      Another kite experimenter who contributed was William A. Eddy. He had arrived at the conclusion that the motive power of a flying machine should be applied at the forward end and that “a drag should be trailed from the rear”. This again was the stabilizing action of the Pénaud tail, and Eddy added perceptively that the fixed tail should be put at a certain distance from the centre of gravity for optimum stability. Here we notice that the modern aeroplane form was again attained by experimental work on kites.

      Professor Zahm contributed with a second paper about “Stability of Aeroplanes and Flying Machines”, and although he did not cover any new ground with regard to stability, he did point out the importance of having the stabilizing fins and tails far removed from the centre of the mass. He also caught a glimpse of aileron action because, in imagining the wings at both sides of an aeroplane fuselage as a series of slats, he indicated that the pilot “could wheel to right or left by giving one set of slats a little different slope from the other”.

      There can be little doubt that the basic shape of the modern aeroplane appeared before the end of the nineteenth century. Langley probably interpreted what most pioneers believed during the last decade when, in an article in the magazine Century in September 1891, he wrote: “Progress is rapid now and it is possible, it seems to me even probable, that before the end of the century we shall see this universal road of all embracing air... travelled in every direction.”

      In the issue of Scientific American of 15 September 1894 in which the Maxim flying machine and its boiler were described, a sensational notice appeared, stating: “Last Tuesday, July 31st, for the first time in the history of the world, a flying machine actually left the ground fully equipped with engines, boiler, fuel, water and a crew of three persons. Its inventor, Mr. Hiram Maxim, had the proud consciousness of feeling that he had accomplished a feat which scores of able mechanics had stated to be impossible.”

      It is not difficult to imagine that this text emanated from the proud inventor himself, especially when it went on to say that “its very success was the cause of its failure for not only did it rise but it tore itself out of the guides placed to limit its flight and for one short moment it was free”.

      In the same year (1894), Chanute published Progress in Flying Machines, a book which comprised a series of articles by him that had appeared previously in the Railroad Journal. It was the most complete description of all experiments with heavier-than-air machines that had ever appeared and it immediately became required reading for all those who were interested in aviation, at least in the English-speaking world, as it was never translated into French.

      At the time of publication Chanute had studied so many forms of flight that he had become slightly confused, and more so because he was just then under the influence of Mouillard and dutifully described all Mouillard’s theories about continuous soaring without the assistance of any kind of engine. In a discussion about the promotion of longitudinal stability, Chanute mentioned three ways of attaining this: first by placing “additional surfaces at a slight angle to the main surface”, which was Pénaud’s system and is now universally adopted. The second, “by placing several surfaces behind each other” which was a reference to the method adopted by Hargrave and taken up by the French in 1905. The third method was the one “universally employed by the birds”. Chanute did not indicate his preference and so left the aviation experimenters without any clear indication as to the way ahead.

      

       S. P. Langley (1890/1896)

      

      In 1890, when Langley had finished his experiments with aerodynamics, he arrived at the conclusion that: “I have not asserted that mechanical flight is practically possible since this involves questions as to the methods of constructing the mechanism, of securing its safe ascent and descent, and also of securing the indispensable conditions for the economic use of the power I have shown to be at our disposal — the condition, I mean, of our ability to guide it in the desired horizontal direction during transport — questions which, in my opinion, are only to be answered by further experiment.”

      Langley’s experiments had shown the theoretical possibility of sustaining 200 lbs in the air for each horsepower “rightly applied”. Steam engines which gave one horsepower for every ten lbs of weight were then available and Langley thought that it was not necessary to defer further experiments, but that the building of flying models should be started at the earliest opportunity. He was already aware that a higher power to weight ratio would be needed than his earlier experiments had indicated.

      To quote again from Langley’s report: “At the time the experiments with flying