The history of aircraft structures underlies the history of aviation in general

The history of aircraft structures underlies the history of aviation in general. Advances in materials and processes used to construct aircraft have led to their evolution from simple wood truss structures to the sleek modern aircraft used today. Combined with continuous powerplant development, the structures of aircraft have changed significantly.
The key discovery that “lift” could be created by passing an airmass over the top of a curved surface set the development of fixed and rotary-wing aircraft in motion. George Cayley developed an efficient cambered aerofoil in the early 1800s, as well as successful manned gliders later in that century. He established the principles of flight, proving the forces of lift, weight, thrust, and drag. It was Cayley who first stacked wings and created a tri-wing glider that flew a human being in 1853.
In the late 1800s, Otto Lilienthal expanded upon Cayley’s discoveries. He manufactured and flew his own gliders on over 2,000 flights. His willow and cloth aircraft had wings designed from extensive study of the wings of birds. Lilienthal also made standard use of vertical and horizontal fins behind the wings and pilot station. Above all, Lilienthal proved that man could fly.
The work of all of these men was known to the Wright Brothers when they built their successful, powered airplane in 1903. The first powered flying machine to carry a man aloft, the Wright Flyer had thin, cloth-covered wings attached to what was primarily truss structures made of wood. The wings contained forward and rear spars and were supported with both struts and wires. Stacked wings (two sets) were also part of the Wright Flyer. This paved the way for all powered aircraft of which helicopters descended. On September 14, 1939, the VS-300, the world’s first practical helicopter, took flight at Stratford, Connecticut. Designed by Igor Sikorsky and built by the Vought-Sikorsky Aircraft Division of the United Aircraft Corporation, the helicopter was this first to incorporate a single main rotor and tail rotor design.