ORIGINAL: Daniel Z
Also, when you enter the inverted harrier to fly it in a straight line, automaticaly add a bit of left rudder (right when inverted) or you will fly in a circle to the left... why? because when you are inverted right thrust is LEFT thrust making torque worse, think about it, all planes I have flown do the same.
This is true, though I have one technical nitpick. It's not torque that's causing the plane to yaw, it's [link=http://en.wikipedia.org/wiki/P-factor]P-factor[/link]. Torque will cause the plane to roll, and would need to be counteracted with aileron input. P-factor occurs when you're flying at a high angle of attack and causes the plane to yaw. This is what you're counteracting with the rudder when flying a harrier.