Wright Bros.

Why Orville and Wilbur could fly

Orville and Wilbur succeeded while others failed because they were bicycle guys.  Their competitors were wagon guys.

Wagons can be turned by brute force while the wagon remains level - just turn the front wheels and the rest of the wagon follows.  The wide wheelbase resists the roll moment - i.e. the product of horizontal centrifugal force towards the outside of the turn, times the height of the center of gravity. 

Bicycles require more finesse since their inline wheels cannot resist any roll moment.  The Wright brothers understood that turning a bicycle requires precise adjustment of the bank angle so that the vector sum of the horizontal centrifugal force vector and the vertical gravitational force vector is always directed from the center of gravity towards the straight line between the two points where the wheels contact the road surface.

(Luckily, bicycles are easier to ride than to explain.)

Early experimental aircraft could barely maintain minimum flying speed ("stall speed") under the best of circumstances.  When a wagon guy turned his craft with rudder, while keeping the wings level, the nose would yaw into the turn, the fuselage blanked the airflow over the inside wing, and drag increased because the airplane was no longer pointed directly into the relative wind.

The aircraft would decelerate due to the increased drag and enter a "skidding-turn-stall" - the first part of the dreaded "stall-spin-crash-burn-die" maneuver.

The Wright brothers knew that they should fly airplanes like they rode bicycles - carefully coordinating bank angle and rudder control to keep their sensed weight straight into their seat.     

"g" load Vs. bank angle in level flight

The g-load is the ratio of the sensed weight to the one-g gravitational weight.  For an aircraft in a level, coordinated turn, this is equal to the reciprocal of the cosine of the bank angle.