OK.... so if you put your lead forearm on a table (aka the plane in a swing) with your thumb up, just curious how people on this board view forearm rotation:
it either
a) stays in the same relationship, and the 'lower bone' and 'upper bone' remain in line, as the lower bone slides on the table (back of had stays 90 degrees)
OR
b) the upper bone rotates around the lower bone, to palm down in the 'backswing' to palm up in the 'forward' swing
OR
c) the 'lower' bone rotates around the upper bone (i.e. counterclockwise, and the palm is up to down
it either
a) stays in the same relationship, and the 'lower bone' and 'upper bone' remain in line, as the lower bone slides on the table (back of had stays 90 degrees)
OR
b) the upper bone rotates around the lower bone, to palm down in the 'backswing' to palm up in the 'forward' swing
OR
c) the 'lower' bone rotates around the upper bone (i.e. counterclockwise, and the palm is up to down