They made some flights with a Lilienthal monoplane; but, finding this unsafe and treacherous, they discarded it in favor of a multiple-wing glider designed by Chanute, which after many empirical modifications in the placement of the sustaining surfaces, assumed the form shown in Plate XVII. This glider resembled the Lilienthal biplane in having the surfaces vertically superposed, the rider below them, and the rudder in the rear; but it was a five-decker whose wings, on either side, could swerve fore and aft, so as to bring the center of lift always over the center of gravity, in order to prevent excessive rearing or plunging. This glider was found very tractable in a twenty-mile wind, and in a thirteen-mile breeze would sail down a slope of one in four.
After further study, the five-decker was replaced by a three-decker; which presently was deprived of its obtrusive and unessential lower surface, thus assuming the familiar form shown in Plate XVII. As will be observed, this was a radically new and elegant design, consisting of two superposed arched surfaces held together by vertical posts and diagonal wires, like a Pratt truss. It was, in fact, the renowned “Chanute glider” which has been copied by so many succeeding designers of biplanes.
The Chanute glider weighed 23 pounds, spread 135 square feet, and readily carried a total weight of 178 pounds at 23 miles an hour. It was provided, as shown, with side planes and a double rudder, and this latter was elastically connected to the main body to insure steadiness of flight, on the principle of the elastic wing margins used by D. S. Brown in 1874. This craft was found easy to manipulate in launching, sailing and landing, a two-inch shift of the pilot’s weight equivalencing a five-inch shift on the Lilienthal monoplane. It was steady at a speed of twenty to forty miles an hour through the air, even when the wind was blowing seventeen miles an hour overground. The angle of descent was 7.5° to 11°, depending on the speed and trend of the wind. The work of gravity expended in maintaining steady flight was at the rate of two horse power for the 178 pounds, a good showing with the rider vertical.
Summer passed before Mr. Chanute could perfect the invention for automatic stability by means of swerving wings; but otherwise the gliding experiments were very satisfactory. The strong and simple biplane evolved during those few weeks of fruitful study, though not an original creation, having been foreshadowed theoretically and experimentally, in the work of Wenham,[30] Stringfellow, Lilienthal, Phillips, and Hargrave, was nevertheless an important contribution to the science of aviation, by reason of its strength and simplicity of design, its efficiency, its stability, and, best of all for that day, its record for good flights and safety. All who could appreciate it understood that the addition of a light motor would transform it to a dynamic flyer, navigable at least in mild weather. The most eager, perhaps, was Mr. Herring; for he had not only mastered this glider, but some years previously had flown successfully rubber-driven models very much resembling it in design. These two aviators, therefore, came to a parting of the ways, Chanute still pursuing automatic stability, Herring impatiently heading for dynamic flight by the shortest route available. Had they continued together on a practical course, they might, ere the close of the century, have anticipated at least the early flights of the French aviators, if they could have constructed or purchased an adequate motor.
After some further development of the aërial glider to adapt it to power flight, Mr. Herring began the construction of a dynamic aëroplane. He had previously built very light steam and gasoline engines,[31] and deemed the latter best for a perfected flyer, though preferring steam or compressed air in a first experimental test.
When seen by the present writer in October, 1898, at St. Joseph, Mich., Mr. Herring was about to launch himself in the compressed-air driven biplane shown in [Plate XVII]. It was essentially a powered Chanute-Herring glider, steadied by a double tail, and controlled by shift of the pilot’s weight, the tail being elastically attached. The writer then suggested that both a glider and a dynamic aëroplane should be controlled entirely by steering and balancing surfaces, on the principle set forth in his paper of 1893; and, in particular, indicated that the lateral balance should be controlled by changing the inclination of the wings on either side, while the double tail should be used to steer and steady the aëroplane sidewise and vertically; in other words, that a torque about each of the three rectangular axes of the machine should be secured from impactual pressure, thus obviating the need for shifting the pilot’s weight. Mr. Herring, while making no objection to this proposal, intimated that he had a device for insuring control without shifting the pilot’s weight, but believed the most important effort for the moment should be to make a short flight with the machine as it stood, for the purpose of enlisting capital, then to add the controlling devices at leisure. He expected to remove the wheels shown in the figure, hold the aëroplane against a stiff breeze from Lake Michigan, start the propellers, strike a soaring attitude, and fly forward for a few seconds against the wind.
The successful accomplishment of such a flight covering an overland distance of seventy-three feet in eight or ten seconds, against a wind of thirty miles an hour, was reported in the Chicago Evening News, of November 17th of that year; but the present writer has not been able to ascertain the reporter’s name, or that of any other witness to the event, which, if true, is well worthy of verification and detailed record.
In following the votaries of passive flight, as represented by Lilienthal and his school, we have overlooked the great man-carrying bird of Clément Ader, one of the most prominent and successful aviators of that active period. If the reports be true, Ader may justly claim to be the first person to navigate the air in a dynamic flying machine. However, it must be observed that his achievements did not at first arouse in France a great pitch of exultation and enthusiasm. There seemed at the time to be some skepticism as to the practicability of his device. But later cordial reparation was made by placing it on the Stand of Honor at the Aëronautical Salon, held in the Grand Palais, at Paris, in December, 1908.
Clément Ader set out in life with the fixed determination to make a fortune, then to build a practical flying machine. Adopting the profession of electrical engineer, he quickly accumulated enough capital, as he thought, to realize his early ambition. He next visited Africa to study at close range the great soaring birds that Mouillard had described with so much admiration and vivacity. Going to Algeria he disguised himself as an Arab, and, with two Arab guides, journeyed to the interior where he watched the great soaring vultures, which he enticed with bits of meat to perform before him their marvelous maneuvers, wheeling in wide circles, and without wing beat, from earth to sky.
After several years of study of the anatomy and flight of birds, Ader began, at the age of forty-two years, to construct an aëroplane. His first machine was a birdlike monoplane mounted on skids, or wheels, and driven by a 40-horse-power steam engine actuating a screw, placed forward. The total weight was 1,100 pounds, the spread 46 feet, the length 21 feet. The Eole, as he called it, received its first open-air test on the morning of October 9, 1890, in the grounds surrounding the Chateau d’Armainvilliers, near Gretz, a portion of the course being so prepared that the trace of the wheels would be visible. When everything was ready for the trial, Ader mounted the machine, in presence of a few friends, ran quickly over the ground, urged by the propeller thrust, then rose into the air and sailed 150 feet. Such is the report of the witnesses to what is claimed as the first flight of a human being in a power-driven flying machine.