For Wilbur and Orville the dream had taken hold. The works of Lilienthal and Mouillard, the brothers would attest, had “infected us with their own unquenchable enthusiasm and transformed idle curiosity into the active zeal of workers.”
They would design and build their own experimental glider-kite, drawing on much they had read, much they had observed about birds in flight, and, importantly, from considerable time thinking. They had made themselves familiar with the language of aeronautics, the terms used in explaining the numerous factors involved in attaining “equilibrium” or balance in flight, where balance was quite as crucial as in riding a bicycle. Lift came from air moving faster over the arched top of a wing, thereby making the pressure there less than that under the wing. Pitch was the lateral tilt of the flying machine, front and back, nose down, nose up. Roll applied to the rotation of the wing, up or down on one side or the other, like a boat rocking. Yaw applied to the direction of the flight, the turning of the plane pointing the nose left or right.
Equilibrium was the all-important factor, the brothers understood. The difficulty was not to get into the air but to stay there, and they concluded that Lilienthal’s fatal problem had been an insufficient means of control—“his inability to properly balance his machine in the air,” as Orville wrote. Swinging one’s legs or shifting the weight of one’s body about in midair were hardly enough.
Wilbur’s observations of birds in flight had convinced him that birds used more “positive and energetic methods of regaining equilibrium” than that of a pilot trying to shift the center of gravity with his own body. It had occurred to him that a bird adjusted the tips of its wings so as to present the tip of one wing at a raised angle, the other at a lowered angle. Thus its balance was controlled by “utilizing dynamic reactions of the air instead of shifting weight.”
The chief need was skill rather than machinery. It was impossible to fly without both knowledge and skill—of this Wilbur was already certain—and skill came only from experience—experience in the air. He calculated that in the five years Lilienthal had devoted to gliders and gliding, he spent a total of only five hours in actual flight. It was hardly enough and not how he and Orville would proceed.
On an evening at home, using a small cardboard box from which he had removed the ends, Wilbur put on a demonstration before Orville, Katharine, and a visiting Oberlin classmate, Harriet Silliman. He showed them how, by pressing the opposite corners of the box, top and bottom, the double wings of a biplane glider could be twisted or “warped,” to present the wing surfaces to the air at different angles or elevations, the same as the birds did. Were one wing to meet the wind at a greater angle than the other, it would give greater lift on that side and so the glider would bank and turn.
With “wing warping,” or “wing twisting,” as it was sometimes referred to, Wilbur had already made an immensely important and altogether original advance toward their goal.
IV.
In the summer of 1899, in a room above the bicycle shop on West Third Street, the brothers began building their first aircraft, a flying kite made of split bamboo and paper with a wingspan of five feet. It was a biplane, with double wings, one over the other, the design Octave Chanute used for his gliders and that was believed to provide greater stability. The wings were joined in the fashion of a bridge truss, with vertical struts of pine and crisscrossing wires. Also included was an original system of cords whereby the operator on the ground, using sticks held in both hands, could control the wing warping.
In early August, Wilbur tested the model in an open field outside of town. Orville, for some reason, had been unable to attend. A few small boys were the only witnesses.
According to Wilbur’s account of the tests [Orville later wrote], the model . . . responded promptly to the warping of the surfaces . . . when he shifted the upper surface backward by the manipulation of the sticks attached to flying cords, the nose of the machine turned downward as was intended; but in diving downward it created a slack in the flying cords, so that he was not able to control further. The model made such a rapid dive to the ground that the small boys present fell on their faces to avoid being hit.
Nonetheless, the brothers felt the test had plainly demonstrated the efficiency of their system of control and that the time had come to begin work on a man-carrying glider.
In April of 1900 Wilbur turned thirty-three. Four months later, in August, Orville and Katharine turned twenty-nine and twenty-six. For her birthday, as Katharine was pleased to tell their father, “the boys” had given her a bust of Sir Walter Scott.