The Rise of the Flying Machine. Hugo Byttebier

superposed planes in order to increase the wing surface without increasing its dimensions and weight in the same proportion. The paper had a great impact on the aeronautical movement in the English-speaking countries.

      In the same year an equally important paper was published by Jean-Charles de Louvrié in France with the suggestive title Vol des Oiseaux, équation du travail, erreur de Navier. De Louvrié declared emphatically that Navier’s calculations were wrong, that the bird was similar to the kite “in which the line is replaced by the living force working on the mass (of air) by the propeller” (the wing tips which in a bird act as propellers). This was certainly a new point of view and de Louvrié went on to state that a bird could soar on rising currents of air, determined by the unevenness of the ground and that flight was nothing more than a balancing act.

      All this was true, but it led several French enthusiasts, eager to copy the bird’s balancing act, to think along lines that deviated from what Cayley had shown, as will be discussed in a later chapter.

      The most important event of the decade was the organization by the Aeronautical Society of the first Aeronautical Exhibition in the world. It opened on the 25 June 1868 at the Crystal Palace in London, and among the seventy-seven exhibits were engines, models and kites.

      The Exhibition lasted eleven days, and was especially important because the French were also present. Earlier during the year, the publication L’Aéronaute had been revived by Abel Hureau de Villeneuve and on 23 May a Société Aéronautique et Météorologique de France was constituted on the model of the Aeronautical Society of Great Britain.

      The new L’Aéronaute started its publication by reporting extensively on the Aeronautical Exhibition of London. A prize of 100 pounds was to be given for the best engine. Sixteen engines were entered and the prize was unanimously awarded to the steam engine built by John Stringfellow for the Henson experiments referred to above.

      The committee, for some mysterious reason, accorded Stringfellow’s engine a power output of one hp. It was later acquired by S. P. Langley for the Smithsonian Institution but on test never approached even the 1/3 hp originally claimed for it. It was also installed in a neat triplane model plane built by Stringfellow but was incapable of making it fly, so the Exhibition produced no artefacts capable of flight.

      The French would have liked to submit Ponton d’Amécourt’s aluminium steam engine but Hureau de Villeneuve refused permission to have it fired up, on the grounds that the manometer was lacking. He was criticized for his decision at the time, but he was probably right.

      Another steam engine at the Exhibition was built by R. E. Shill, whose “turbine injector power unit” was said to be capable of achieving 1 hp. Shill subsequently collaborated with Thomas Moy, who became bitten by the aeronautical bug at about that time (having exhibited “a mariner’s kite for use in rough weather” at the Exhibition), and subsequently built what was called “Thomas Moy’s Aerial Steamer”. The engine for the first experimental model worked at a pressure of 160 lbs/sq in. and produced three hp for a weight of 80 lbs in 1874.

      The model was tested in 1875 but instead of the hoped-for 35 mph take-off speed, only 12 mph was reached and no flight was achieved. Again we see the sanguine response of the pioneers when, after the unsuccessful tests, Moy proposed building a full-size aeroplane with a steam engine of 100 hp “capable of carrying several men” according to Chanute.

      It was no wonder that, in one of his reports on the Exhibition to Paris, Hureau de Villeneuve stated sadly that the great enthusiasm aroused in France at the prospect of realizing aerial locomotion in the very near future in 1863 had all but died out and, like Cayley sixty years before, he reflected on the fact that the big problem remained the engine, or rather the lack of a satisfactory one.

      In his opinion, it was not a matter of cost and he declared: “At the present stage it does not really matter whether the aero engine consumes alcohol, ether, diamonds or attar of roses. The important thing is to fly at any price.” Economy would be achieved by subsequent practice.

      The year 1868 saw another outstanding feat, the invention of the aileron system for controlling the lateral movements of an aeroplane. M. P. W. Boulton registered a patent (No. 392) that year for a system “to prevent [aerial vessels] turning over by rotating on the longitudinal axis”. In his specification Boulton referred to Cayley’s proposals to achieve inherent lateral stability by using a dihedral angle of the wing but he thought that it could become “desirable to provide a more powerful action preventing rotation of the body in this direction”.

      The system described (“vanes or moveable surfaces attached to arms projecting from the vessel laterally”), the aileron system as it is called today, was proposed as a safety device in order to redress the aircraft if, for some reason it should begin to roll as a result of a gust of wind or an upset balance. The purpose of the invention was to ensure that “the balance of the vessel is redressed and its further rotation prevented”.

      This was aileron action as it is used on the great majority of modern aeroplanes although no mention was made for its use in order to make a turn. That had not yet entered the vision of the aviation pioneers and would come much later.

      Thus, the modern aeroplane was slowly taking shape. A light and powerful engine, fixed and rigid wings of high aspect ratio, a horizontal and vertical movable rudder at the rear, ailerons for controlling unwanted rolling movements were contemplated in theory before the end of the 1860s.

      There was only one quality lacking: inherent stability in the longitudinal sense. Cayley’s speculations in 1809 were not yet adequate for that purpose. Longitudinal stability, the most important of all, would now be shown shortly afterwards to an admiring aeronautical community in Paris by the second great aeronautical genius of the nineteenth century, after Sir George Cayley, a figure who would dominate the aeronautical movement during the next decade: Alphonse Pénaud.

       Alphonse Pénaud

      As Hureau de Villeneuve sadly remarked in 1869, most of the enthusiasm for aviation that had been aroused earlier had again been lost. But at the end of the decade it was revived with great force by a single man whose genius dominated the next few years.

      A complete biography of the extraordinary and talented Alphonse Pénaud is still lacking but a special issue of the French aeronautical monthly Icare (Nº 38 of 1966) was devoted to him. Compiled by the late Charles Dollfus, at that time France’s most respected historian of aeronautics, it is the best source of information about Pénaud’s life and work.

      Born on 31 May 1850, Pénaud was the son of an admiral but he was unable to follow a naval career because he was incapacitated from the age of nineteen by a hip ailment. His great mental energy then found another outlet in the furtherance of dynamic flight.

      In 1869 he started his aeronautical activities by building a small-scale helicopter along the lines followed by Launoy et Bienvenu in 1784 and by Sir George Cayley in 1796. In the course of his experiments he found that rubber, when cut into fine strands and suitably twisted would provide more energy than an equal weight of rubber working under tension, as had hitherto been used.

      His twisted-rubber helicopter model was shown for the first time on 20 April 1870 to de La Landelle and Hureau de Villeneuve, but Pénaud, who had become very interested in the flying exhibitions of Joseph Pline’s Papillons was gripped by the possibilities of fixed-wing flight and decided to find out if he could build a self-propelled flying aeroplane by using his twisted-rubber engine. No aeroplane type, not even Stringfellow’s steam-powered triplane of 1868, had been able to achieve flight so far.

      Beginning his research by observing the fall of diverse surfaces and by studying Pline’s models, Pénaud soon designed a small-scale aeroplane which used twisted rubber as a power source. He had to apply the full keenness of his mind to make this model fly in perfect balance and find a solution to the hitherto unsolved problem of how to obtain longitudinal stability.

      The model plane which was built according to his calculations received the name “Planophore” and flew for the first time in public on 18 August 1871 before an admiring group of fellow associates of the newly