# Do all airplanes have the same turning radius when operating under the same conditions regardless of size and weight?

Would any airplane in coordinated, turning, level flight have the same turn radius at a given combination of no-wind ground speed, bank angle, and density altitude as another airplane of significant difference in size and/or weight?

For example, if a small airplane and a super heavy airplane could match speeds at the same density altitude, and they both held the same bank angle while holding altitude, would they generally be expected to have the same turn radius if they weren't slipping or skidding?

If yes, what are some examples of exceptions to this if any?

## 1 Answer

Take the no-wind case for simplicity. For a given bank angle, and a given groundspeed (airspeed), there is only one turn rate that will center the slip-skid ball, so the answer to the question must be "yes", assuming that "coordination" is being defined in relation to the slip-skid ball and not some other instrument such as a yaw string.

Due to various interesting aerodynamic effects that happen when an aircraft's size is significantly large in relation to the turn radius, flying with the slip-skid ball completely centered will not always be completely optimum. Similarly, the answer to the question would be different if the question were to specify that "coordination" were to be measured in reference to a yaw string or other similar instrument located at some given point on the aircraft, rather than a slip-skid ball. For more, read "Circling the Holighaus Way" by Richard Johnson.

• I could go into the flying-by-reference-to-yaw-string case in more detail but am inclined to leave that as an answer to a separate question, should one be asked-- – quiet flyer May 27 '19 at 20:56