After reading an article on Arc-Flash in regards to the position of the bus (horizontal or vertical) and the way the flash projects itself depending on the position. Has there been any research done regarding copper vs. aluminum bussing? The makeup (properties) of each material is different so how could this affect the flash? Does anyone know it this has been looked at?

I haven't seen that discussed anywhere. Don't confuse things even more!?

The closest I have seen is in a paper by Stokes and Oppenlander from University of Australia, "Electric arcs in open air." 1991(?).
In the paper, they discuss the magnetic effects of the material and the arc movement.

May I know the name of the article your read? I was also told by consultants that the rating of bus horizontal/vertical has a huge affect on fault current. I am looking for to prove this.

I think the article that Mike is referring to is "Effect of Electrode Orientation
in Arc Flash Testing" availabe for download from Ferraz Shawmut, here:
http://us.ferrazshawmut.com/arcflash/getting_help/downloads/05IAS_11P7_web.pdf

I don't recall seeing anything about bus ratings in the paper, it deals with the arc and the effects of bus orientation at the point of the arc. I would be curious as to anything you find out about bus ratings on fault current. I don't understand how it would affect it, other then larger bus having a lower impedence. I wouldn't think that bus bracing would have any effect. But I didn't stay at a Holiday Inn Express last night, so I could be wrong.