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I feel obligated to go out and try this my self, but maybe someone has done this already and can help.

The issue is that a centered "ball" position is affected by gravity more and more as the bank increases, whereas the yaw string is measuring only airflow in relation to the longitudinal axis of the aircraft.

Another way to determine best coordination is to see if the aircraft holds a level banked turn at a given throttle setting, which, if fully coordinated, would be flying at the bottom of its drag curve for that manuever. Increase in drag from uncoordinated flight should lead to an altitude loss.

Has anyone seen a difference in the yaw string and ball? Is it significant enough to differentiate between the two in a steep turn?

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  • $\begingroup$ Re drag-- google an article called "Circling the Holighaus Way". $\endgroup$ May 13, 2022 at 12:50

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String is always better, if you can use it. The ball is less sensitive and can be thrown off a bit, such as when flying a twin single engined, and the rudder is applying lateral thrust to compensate for asymmetric engine thrust.

Coordinated flight in a twin is achieved with a bit of wing down into the live engine, normally 5 degrees, and the result is coordinated flight with the airplane banked and the ball offset in the vial about half a ball to one ball width toward the live engine, because that's where true "down" is.

If you have a yaw string, the string is aligned, which means the airflow is aligned, or it's not. On any airplane that doesn't have an engine in the way blowing on the windshield, it's desirable to have a yaw string, if only because it's right in your field of view.

Biggest thing is you have to get used to the backwards reference - string to the right requires left rudder for example, opposite the ball indication. I used to tell glider students, as a memory aid, "Think of the yaw string as a poisonous snake - step away from it."

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