The Wright Brothers

by Fred C. Kelly

The total flying time during 1904 was only 45 minutes. But the knowledge and experience gained from that three quarters of an hour were of almost inestimable importance.

Toward the end of May, 1905, the Wrights began assembling a machine all new with the exception of the motor and the propeller-driving mechanism. Strengthening of the structure at places where the previous machine had been too weak in making landings added about 25 pounds more weight. The principal changes, however, were in wing design, addition of some new features not in the earlier machines, and in making the wing-warping and operation of the tail rudder independent of each other. The camber of the wings was changed from 1-25, used in 1904, back to 1-20 as used in 1903 at Kitty Hawk. This change was to enable the machine to get off at a slower speed.

The most radical change was the addition of two semi-circular vanes, called “blinkers,” between the two surfaces of the front elevator. This device was later patented by the Wrights. The purpose of the “blinkers” was to assist the rear rudder in overcoming the unequal resistances of the two wings when they were warped while making a turn. Gliding experiments in 1902 had shown that the pressure on a fixed vane in the rear of the wings tended to speed the higher wing when the machine slipped in the direction of the lower wing, and caused a tail-spin. The vane had to be made movable to relieve this pressure. It now occurred to the Wrights that if a fixed vane were placed in front of the wings, instead of behind them, its effect would be the reverse of that when the vane was in the rear, and that there would be less need of operating the rear rudder to overcome the unbalanced resistance of the two wings. Moreover, when the machine slipped inward while “banking” a turn, the speed of the low wing would be increased and a tail-spin avoided. The operation of the rear rudder could now be made independent of the wing-warp without danger.

It was found that the “blinkers” entirely removed the danger of tail spinning but that they added to the difficulty of steering, both when flying straight and when making turns. Consequently they were not used in all the flights. (In modern planes the effect of the “blinkers” is gained by extending the fuselage far out in front of the wings.)

Though tail-spins could be avoided without use of “blinkers,” by carefully observing the little piece of string that indicated side slip, yet they sometimes occurred. In one flight, in September, 1905, when the “blinkers” were not on the machine, Orville suddenly discovered he was in a tail-spin and that he was about to come down in the top of a forty-foot thorn tree. The thorns were several inches long, and the idea of falling through them to the ground was not alluring. Orville quickly turned the machine into an almost vertical dive while turning in a circle 50 to 100 feet in diameter. The inner wing of the machine hit a branch of the tree, imbedding a thorn in an upright, and tore off the branch. In the dive, the higher wing, because of much greater speed, soon passed the lower wing in the downward plunge and itself became the low wing. The machine thus was in a steep bank with the high side toward the tree, just the opposite from what it had been before. When Orville turned the elevator to avoid striking the ground, the machine turned suddenly and unexpectedly away from the tree, because, in this steeply banked condition, the elevator exerted more pressure laterally than it did vertically. (When an aeroplane is banked to 45 degrees the elevator serves just as much for a rudder as for an elevator, and the rudder just as much for an elevator as for a rudder.) Though the machine lightly touched the ground, Orville flew it on back to the hangar, where the branch of the tree was found still clinging to the upright. It had been the practice of the Wrights to dive the machine to recover speed in a stall; but this quick recovery was from an entirely different cause—the great difference in the speeds of the two wings.

An amusing flight by Orville in 1905 was made after some weeks of inactivity in flying and after the machine had undergone a number of changes since his last flight. When the machine left the starting rail it began pitching like a bucking broncho. Orville wanted to stop, but at every plunge the plane came down so steeply he did not dare attempt a landing. As soon as he got control of the machine, after going three or four hundred feet, he did land safely. Wilbur rushed up to inquire why he had stopped just when he had really got going. Orville explained that he would have landed even sooner, but had taken the first opportunity to stop without smashing the machine to pieces.

Though the rudder and wing-warp were entirely independent of each other in all the flights of 1905, the Wrights several years later resumed having the two controls interconnected, to operate together, but with an arrangement needed for modifying their relationship when making turns.

Another change that improved control of the 1905 machine was in giving the wings considerably less angle at the tips than in the central part. By this arrangement, the tips stalled later than other parts of the wings and some lateral control remained even after the central part of the wings were in a stalled condition.

After the Wrights had made the blades of their propellers much wider and thinner than the original ones, they discovered that the performance of the propellers in flight did not agree closely with their calculations, as in the earlier propellers. They could see only one reason for this, and that was that the propeller blades twisted from their normal shape under pressure in flight. To find out quickly if this was the real reason, they fastened to each blade a small surface, like an elevator, out behind the blades, set at an angle to balance the pressures that were distorting the blades. They called the surfaces “little jokers.” When they found that the “little jokers” cured the trouble, they dispensed with them and began to give the blades a backward sweep, which served the same purpose.

In the flying season of 1905, the control of the machine was much improved by increasing the area of the front rudder from 50 to 85 square feet, and by moving it to nearly twice the distance from the wings. This added distance made response to the movement of the rudder slower, and control of the machine much easier.