The Rise of the Flying Machine. Hugo Byttebier

the inherent stability of his most efficient gliders, those which he used from 1892 to 1894. It was because he wanted to achieve longer flights, which in turn demanded larger wings, and as he also wanted to fly in stronger winds, this required better control and, added to that, he also wanted to incorporate a motor. All these factors made for larger and heavier aeroplanes, but the steering of these by means of movements of the body was becoming increasingly hard with every pound of weight that was added.

      The idea of introducing movable auxiliary surfaces for better control was correct, but the relinquishment of inherent stability was not. It would take ten more years before the aircraft designers became conscious of the fact that controls had to be superimposed on an inherently stable construction and that to abandon stability in order to obtain better control was a grave mistake.

       Octave Chanute (1890/1894)

      Ader, Maxim and Lilienthal were not very interested in each other’s experiments. Maxim called Lilienthal a parachutist and Lilienthal countered by referring to Maxim’s costly trials as “how not to do it”.

      But in the United States a man who was keenly interested in all aeronautical pioneers was becoming active and was preparing to devote the last years of his life exclusively to the promotion of human flight. By so doing he came into contact with most of those who were involved in aviation during the eventful last decade of the nineteenth century. This man was Octave Chanute.

      His interests soon turned him into an indefatigable letter-writer. One of the first letters he wrote when he returned from his trip to Paris was to Mouillard, along with a copy of the paper Chanute had delivered at the International Aeronautical Conference of 1889.

      Mouillard replied on 16 April 1890, thanking Chanute for his pamphlet but commenting on his “deplorable habit of paying little attention to writings pertaining to pure mathematics” and indicated that he was proceeding instinctively and was being moved by his tremendous enthusiasm. He ended his letter with “enthusiastic greetings”, after referring to his “professors” in the following terms: “In case some theoretical problems are confronting you in your experiments I would like to put my professors at your disposal; they are neighbours of mine, two vultures, which are brilliant demonstrators.”

      It was clear that Mouillard remained completely devoted to the intricacies and wonders of bird flight and his enthusiasm was soon shared keenly Chanute, who became as convinced of the necessity of imitating the “instinct of the bird” as Mouillard.

      Now that Mouillard had found a kindred spirit there was no stopping him, and on 20 November 1890, in another long letter to Chanute, he explained how a bird warped the tip of its wing in order to arrest its movement through the air on that side, thereby inducing a powerful turning movement. Mouillard explained that he had reproduced this movement several times and that the displacement of the body (just as Lilienthal was able to do a few years later) or the diminishing of the wing surface was far less effective than the warping of the wing tips which he called a “brutal means of steering”.

      Chanute was greatly impressed by Mouillard’s elucidations and this was to have a far-reaching effect on the aviation movement, although that effect was not unequivocally beneficial.

      Meanwhile Chanute worked assiduously to sort out the notes on aviation that he had been making since 1855, and which he now arranged for a series of articles that were published in The Railroad and Engineering Journal, starting with the October 1891 issue. The series continued through twenty-seven issues up to January 1894.

      As though his voluminous correspondence and his articles were not enough, Chanute had returned from Paris with the intention of organizing an international air conference like the one held in Paris in 1889.

      He was assisted in the organization of this new undertaking by a young professor at Notre Dame University, Albert Zahm, who became secretary to the conference. It was held in Chicago from 1 to 4 August 1893 in connection with the Columbian Exposition. It was the third international aeronautical conference after the one held in London in 1868 and the other in Paris in 1889.

      The first paper was posthumous. It was a very cogent study, “On the Problem of Aerial Navigation”, written by C. W. Hastings in 1892, shortly before his death at the age of just thirty-three.

      Hastings explained that the first requisite of flight was lift and remarked that scientists were willing to admit that “when sufficient progress shall have been made in mechanical science, true aerial navigation will be possible and will be accomplished.” This gainsays the popularly held theory that most scientists at some time or other had declared human flight to be an impossible dream.

      Hastings then continued by explaining that the second requisite for a flying machine was stability. “If an apparatus possessed the necessary supporting surface and a sufficient motor and motive instrument to propel it through the air at sufficient speed, yet aerial navigation would be far from accomplished. The machine might still lack stability.” These ideas were clear and concise and were formulated in 1892 by a scientist of great insight.

      Hastings proposed the dihedral angle for transverse (lateral) stability and suggested that a vertical keel should be added, explaining that “Such keel cloths may terminate in a vertical rudder and thus allow of steering the machine.” The vertical fixed tailfin for stability and a vertical rudder for steering were here proposed as a combined tail as exists on nearly all modern aeroplanes.

      For longitudinal stability Hastings advocated the fixed horizontal Pénaud tail at the rear, but remarked that “it will be somewhat wasteful of power”, which was correct but inevitable. The different methods proposed to obviate this slight waste of power by designing a fixed tail at the front (the so-called canard form) were never able to provide safety equal to the still universally adopted Pénaud system.

      There was no mention of lateral control by means of ailerons or similar devices, so that Hastings followed in the footsteps of Sir George Cayley and Alphonse Pénaud when specifying the priorities required of a machine able to carry a human operator.

      Many of the papers presented at the conference were dedicated to the intricacies of soaring flight, including several by Frenchmen. Chanute probably translated these himself.

      He had also asked Mouillard to contribute, and Mouillard (who lived in Egypt) duly obliged with a paper entitled “A Programme for Safe Experimenting”. Mouillard’s idea of experimenting safely was to use a tailless glider “so designed as to admit of adjusting the wings to the speed of the wind and of thrusting their tips forwards of backwards of the center of gravity so as to change the angle of incidence at which the machine needs the wind”. He duly referred to d’Esterno and Le Bris and repeated his conviction (which he had already propounded in his book of 1881) that: “Ascension can be effected by skillful utilization of the power of the wind and no other force is required.”

      In Mouillard’s opinion, one had only to move the tips of the wing forward sufficiently for the machine to be lifted. He also insisted on “powerful means of steering it horizontally” so as always to be able to meet the wind head on. This steering effect was to be obtained by lowering the tip of a wing, as he had already explained in his letter of 20 November 1890.

      Chanute had become so intrigued by Mouillard’s supreme confidence and the means he proposed, that he not only assisted Mouillard financially to build a glider (that was never tested) but he also helped him to apply for a patent in the US. Based on his idea of a wing-warping glider, Mouillard’s patent was filed by Chanute on 24 September 1892 and issued on 18 May 1897. Claim 12 clearly covered a soaring machine “having (the wing’s) rear edge free from the (main) frame of the wing and cords attached to said rear edge for pulling it downward”.

      Another renowned contributor was S. P. Langley who, although not committed to the unstable soaring machine, as his future activities would show, had become interested in finding a reason for the problem that still appeared inexplicable to many: why a bird could remain in the air with outstretched and unmoving wings for long periods of time without losing height. The solution Langley had found