Aircraft principal axes

On an aircraft, these are intentionally produced by means of moving control surfaces, which vary the distribution of the net aerodynamic force about the vehicle's center of gravity.

On a spacecraft, the movements are usually produced by a reaction control system consisting of small rocket thrusters used to apply asymmetrical thrust on the vehicle.

Normally, these axes are represented by the letters X, Y and Z in order to compare them with some reference frame, usually named x, y, z.

The yaw axis has its origin at the center of gravity and is directed towards the bottom of the aircraft, perpendicular to the wings and to the fuselage reference line.

[3] The term yaw was originally applied in sailing, and referred to the motion of an unsteady ship rotating about its vertical axis.

[citation needed] In aeronautical and aerospace engineering intrinsic rotations around these axes are often called Euler angles, but this conflicts with existing usage elsewhere.

[citation needed] The first aircraft to demonstrate active control about all three axes was the Wright brothers' 1902 glider.