Arrow

I'm making a custom archery system, and have succeeded in making the arrow follow a parabolic path.
I now need to make the arrow 'turn' up and down as it is flying.
I.e. i need the direction the arrow points in to change as it moves so that it strikes the ground.
Currently, it just flies up and down but always pointing horizontally and looks really weird.

So what trigger (GUI or in words please) do i use to change the pitch of the arrow?
Does it have anything to do with the "maximum pitch" options of the model?

In case you're wondering, the arrow is a dummy unit with the archer/hyppogryph etc arrow model.

You could try the 'lock body part' trigger actions to change the facing angle.
But really I guess it would be better to edit the arrow model and give it a custom walk animation.