Originally Posted by gaRCfield

There are a lot of things at play that cause a plane to want right thrust:
-spiraling air stream
-torque
-gyroscopic effect
-p-factor

The contra planes combat almost the whole list.

The props with less area at the hub would have less P-factor effect, since the portion of the prop with the highest pitch is eliminated.

Whoever said spiraling air 'doesn't exist' is likely a Republican Scientist who moved to aerodynamics after disproving climate change.