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FizicistsRool

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**Precise definition of "yaw"**

I'm googled "yaw" for the afternoon and there is a detail that I'm not finding. *One* of my understanding of yaw from my readings is that it is the angle between two /vertical/ planes, one containing the velocity of the moving object and the other containing "longitudinal" axis of the moving object i.e. the front-to-tail axis of the fuselage of an aircraft.

This is my own cobbled together idea of waht yaw could *possibly* mean. Nowhere is yaw defined exactly in these terms. Instead, yaw is explained in terms of rotation around the vertical axis, where it sometimes seems that vertical axis refers to the "longitudinal" axis, and somtimes it seems to refer the gravity vector. For now, I assumed the latter.

Even so, there is the question of precisely how to measure the angle between the velocity vector and the direction in which the moving object is facing. The possibilities that come to mind are:

1. Just measure the angle between the two.

2. Both vectors projected onto a completely horizontal plane

3. Both vectors projected onto a plane containing (1) the velocity vector and (2) the intersection of the horizontal plane with the plane that is perpedicular to the velocity vector.

4. Both vectors projected onto a plane containing (1) the "longitudinal" vector and (2) the intersection of the horizontal plane with the plane that is perpedicular to the "longitudinal" vector.

5. Both vectors are projected onto the plane containing (1) the "longitudinal" axis and (2) the wing-tip-to-wing-tip axis.

Thanks for any clarification