Arrangement of propeller-driving chains and casings on original Wright 1903 machine displayed in the Smithsonian Institution. Courtesy, Smithsonian Institution.
The brothers decided to use two propellers on their powered machine for two reasons. First, by using two propellers they could secure a reaction against a greater quantity of air and use a larger pitch angle than was possible with one propeller; and second, having the two propellers run in opposite directions, the gyroscopic action of one would neutralize that of the other. The two pusher-type propellers on the 1903 powered machine were mounted on tubular shafts about 10 feet apart, both driven by chains running over sprockets. By crossing one of the chains in a figure eight, the propellers were run in opposite directions to counteract torque. The propellers were made of three laminations of spruce, each 1⅛ inches thick. The wood was glued together and shaped with a hatchet and drawshave.
The Powered Machine, 1903
The 1903 machine had a wingspan of 40 feet, 4 inches, a camber of 1 in 20; a wing area of 510 square feet; and a length of 21 feet, 1 inch. It weighed 605 pounds without a pilot. The machine was not symmetrical from side to side; the engine was placed on the lower wing to the right of center to reduce the danger of its falling on the pilot. The pilot would ride lying prone as on the gliders but to the left of center to balance the weight. The right wing was approximately 4 inches longer than the left to provide additional lift to compensate for the engine which weighed 34 pounds more than the pilot.
Fore-and-aft control was by means of the elevator in front, operated by hand lever. The tail of the machine had twin movable rudders instead of a single movable rudder developed in the 1902 glider. These rudders were linked by wires to the wing-warping system. Their coordinated control mechanism was worked by wires attached to a cradle on the lower wing, in which the pilot lay prone. To turn the machine to the left, the pilot moved his body, and with it the cradle, a few inches to the left. This caused the rear right wingtips to be pulled down or warped (thus giving more lift and raising them) and the rear left wingtips to move upward, and at the same time the coordinating mechanism introduced enough left rudder to compensate for yaw. The rudder counteracted the added resistance of the wing with the greater angle and the resulting tendency of the machine to swing in the opposite direction to the desired left turn, as well as aiding the turn on its own account.
Wright 1903 machine (rear view) in the Smithsonian Institution showing attachments on the lower wing. Courtesy, Smithsonian Institution.
Plans of the Wright Brothers 1903 plane. Courtesy, Smithsonian Institution.
