Does draw legnth have any impact on arrow cast?

Meaning, if you have two bows of the same draw weight but one draws to 28" and the other at 31". Will the 31" bow cast the arrow further?

All other things being equal, yes.  Since the force is acting on the arrow longer, there will be more energy transferred to the arrow, and thus the bow drawn to the longer length will cast an arrow further.

However, all other things are not equal.  If the bow drawn to 31" is a real dog, due to inferior construction or materials, it will not cast an arrow as far as the 28" bow.

Yes.  That's the main reason that crossbows have to have such a high poundage draw.  Their short power stroke is an efficiency killer.

Very cool. Trad Gang Myth Busters!!