Originally Posted by Jim Lee
If you are rolling to the right and the plane pulls (yaws) to the right , You need to reduce the down throw. (Not enough differential)
If the plane rolls (yaws) opposite of the direction of the roll, You need to increase the down throw. (too much differential) If the plane stays on the same heading and neither pulls (yaws) to the right or left, You don't need any differential.
Isn't that exactly backwards? The down going wing is the one to have it's lift vector rotated forward by the roll, and the up going wing's vector is rotated backwards, resulting in yaw away from the direction of roll.
The amount of adverse yaw depends on the speed of the airplane (more adverse yaw at low speed) and the load factor (G) (more adverse yaw at high load).
When you add differential there can also be a pitch effect. Adding more up going aileron than down can produce a pitch down effect when you only want roll.
My Osiris rolls pretty axially with no differential, and until my perception and left thumb get smart enough to notice and correct any adverse yaw that does occur, I'm sticking with no differential.