In the early days of flight, Glenn Curtiss was the primary American
competitor to the Wrights. A major difference between the Wright and
Curtiss products was pilots controlled the planes. Curtiss' Model D
airplane was controlled with ailerons, small hinged control surfaces
mounted between the wings, rather than wing warping, which deformed the
entire wing and was protected by the Wright Brothers' patent. Curtiss
also used a different control system than the Wrights. While the Wrights
used a series of levers, Curtiss used a wheel to operate the front
elevator and rear rudder and operated the ailerons with a shoulder yoke.
This meant that when a pilot wanted to turn, he or she simply leaned in
the desired direction, just like riding a bicycle or motorcycle.