Wright Controls

In the Wright brothers’ 1902 glider and their 1903 Flyer the pilot had a vertical lever for the left hand that was pulled back to increase foreplane incidence. The pilot lay on a cradle that shifted sideways on tracks to cause wing warp. To roll to the left the pilot decreased the incidence of the outer left wings and increased the incidence of the outer right wings. The rudder motion was mechanically connected to the wing warp mechanism to turn the nose left when the pilot wished to lower the left wing, and vice versa for lowering the right wing, thereby overcoming the adverse yaw due to wing warp.

When they began to fly sitting up in 1905, the Wrights retained the left-hand vertical lever for foreplane incidence but added a right-hand vertical lever for wing warp and rudder. They moved the new right-hand lever to the left for left wing down and forward for nose – left yaw. The right-hand lever was moved to the right for right wing down and aft for nose-right yaw. Turn coordination required the pilot to phase control motions, leading with yaw inputs. These unnatural control motions had to be learned and practiced on dual control machines or simple simulators. Bicyclists to the last, they never used their feet for control. They retained this scheme until 1909. Since wing warping involved considerable elastic deformation of the wing structure, they later changed the fore-and-aft motion of the right – hand lever to wing warp and mounted a new, short lever on its top for side-to-side movement to control the rudder. When the Wrights abandoned the all-moving foreplane array for an all-moving rear horizontal tail in 1911, the left-hand lever still controlled its incidence, but now reversed.

The Wrights’ patent was for mechanically linked roll and yaw controls. Other airplane builders, notably Curtiss, built airplanes with ailerons, rudders, and elevators, providing independent three-axis control. Curtiss and others asserted that the Wright machine now had independent three-axis control, but U. S. courts upheld the Wright patent against them. The courts maintained that the coupling of roll and yaw controls in the Curtiss machines existed in the mind of the aviator and was essential to the art of flying. Therefore, the Curtiss independent three-axis control infringed on the Wright patent!