Hi, I wanted to know if there was a simple way to move an arrow perpendicular to a mesh?
The method is not important to me, the arrow may be a GUI or a physical object.
Thanks 
I don’t know how dynamic you want this to be, but one way is to put the arrow in a gameobject so that it’s side is square with the z-axis. The use transform.lookat to point the\is parent gameobject to the square surface. you can also child an empty gameobject inside the object with the surface and make that the target of the lookat.
kindof a cheat, but it works fine!