When the Wright Brothers first tried to roll the aircraft using wing warping the result was disastrous. They noticed that along with the rolling, the airplane took an unintended turn. They called it a steering reversal problem (Fig.1A). This phenomenon is now called Adverse Yaw. The physics behind the adverse yaw are now well understood. The airflow above the high angle wing region produces high drag. On the other tip the drag force is low. The difference in the drag force makes the airplane yaw as shown (Fig.1B).

How rudder arrangement helped to overcome yaw?

The Wright Brothers overcome this issue with the help of a rudder arrangement (Fig.2A). If the aircraft goes yawing in this way, they turn the rudder in such a way that the torque produced by the rudder would exactly cancel the adverse yaw torque. The Wright Brothers made another smart move. Since the rudder had to be operated whenever there was wing warping, they connected the rudder and wing warping controls together. Both these motions were simultaneously operated by the hip control. By using these controls effectively, the Wright Brothers were able to give the aircraft the stability needed, pitch the aircraft to climb up or climb down and make a smooth turn by banking the aircraft.

Why did the Wright Brothers use the opposite direction of rotation for the blades?

The opposite direction of rotation for the blades was to cancel the Gyroscope effect of a rotating wheel. You already know that any rotating object has an Angular momentum. For instance you just assume that the Wright Brothers designed the aircraft with the blades spinning in the same direction. Now the pilot decides to pitch the aircraft by lowering the elevator. The lowering of the elevators would obviously produce a torque as shown in (Fig.3). However, the aeroplane would not pitch upwards as expected, due to the angular momentum of the blades. Instead, it would take an unexpected side turn. This unexpected phenomenon is known as Gyroscopic precession.

Gyroscopic precession conforms perfectly with Newton’s 2nd Law Of Motion. Due to this the direction of change in angular momentum is the same as that of the torque applied. The only way to overcome such unexpected behaviour is by eliminating the very cause of it, the angular momentum of the spinning blades. That is exactly what the Wright Brothers did with 2 blades spinning in opposite directions.

It is astonishing to discover that the Wright Brothers thought about such detailed engineering points, despite their limited formal education.

That’s all, I hope you might have found this article interesting.

Thanks for reading !

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