# The effect of mass on airplane turning radius?

## Main Question or Discussion Point

I've been trolling for this answer on the Internet but can't find a simple explanation.

If I have two airplanes of different mass, both flying at the same speed, which plane has the larger turning radius and why? It seems like the more massive plane would require the larger turning radius due to its greater inertia. Can a plane's yaw, pitch, and roll be used to counter for this effect?

Thanks very much.
Dirk

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mfb
Mentor
For regular curves, the pilot can choose the curve radius. There is some limit, of course*, but that is certainly not in the range of regular operations.

If all other conditions are the same**, I would expect that the airplane with a larger mass has a larger curve radius.

* do you count diving? It really reduces the curve radius ;).
**well, they cannot be exactly the same, as one airplane needs more lift than the other one

AlephZero
Homework Helper
If the plane has more mass, the wings must produce more lift to maintain level flight (i.e. to make lift = weight).

Therefore, (to a first approximation) for the same amount of roll, the turn radius is independent of the mass, but only depends on the airspeed. The proportion of the lift (perpendicular to the wings) that is turned into centripetal force depends only on the roll angle. More centripetal force, acting on more mass, gives the same centripetal acceleration and the same turn radius, if the speed is the same.

But in practice, heavier planes tend to generate more lift by flying faster than light ones, which explains why small planes tend to make sharper turns than big ones for the same amount of roll.

Note: the above is about a non-aerobatic aircraft flying a circle at constant altitude. If you include motion in 3 dimensions and/or aerobatics, the answer would be a lot more complicated!

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