Four Principles for Harnessing Lift

Orville and Wilbur Wright began their quest to develop a manned, sustainable, heavier-than-air flying machine in 1896. They were running a small chain of successful bicycle shops when they heard that Otto Lilienthal, a German engineer who built and successfully flew manned gliders, had died while flying. Lilienthal's death was a shock to the world, because "the flying man" had been studying aeronautics for over two decades, had amassed extensive experimental data in his "lift tables," and had made two thousand brief flights in sixteen different gliders. The Wright brothers wondered why a man as knowledgeable and experienced as Lilienthal had died; they were also restless to expand their work beyond their bicycle shops.

The Wright brothers' research into aeronautics began in earnest in 1899, when they requested all of the information that the Smithsonian Institution could provide them on flying and began devouring materials on the topic. They learned that to build a machine that could harness the power of lift the machine would need

1. forward motion

2. through the air

3. properly designed wings

4. flight controls—a means of adapting to flight conditions

Scientists discovered the first two principles centuries before the Wright brothers began working on the problem: if the particles of a fluid substance such as air move over the top of an object at a faster rate than the particles moving under the bottom of the object, then the particles under the bottom of the object put pressure on the object, lifting it upward.

Lilienthal worked extensively on the third principle, compiling data on how different wing designs would generate different degrees of lift. Lilienthal's problem, however, came from trying to adapt to the changes that occurred in the air. Airplanes need to achieve a degree of stability while in the air, but the circumstances in the air often change. Airplanes, then, must adapt to these changes. Lilienthal tried to solve this problem by moving his body around on the surface of the glider. This was an unreliable means of adapting, so it was here where the Wright brothers began to focus their attention.

Many scientists and enthusiasts in the Wright brothers' day thought that flying machines would achieve stability through features of the machines' design. They did not think that humans could adapt to changes in wind currents swiftly enough. In contrast, the Wright brothers believed that humans could adapt because of their experiences with bicycles, which are unstable yet remain controllable. Thus, to make a flying machine that was unstable but controllable, they would need controls that would allow a pilot to adapt. And because air currents can change along three dimensions (raising one side of the aircraft while lowering the other, raising and lowering the nose of the aircraft, and turning the nose of the aircraft right or left), they would need controls for all three dimensions. The problem was figuring out how to create these controls.