Unsupported Precision Round Rail Calculator

[Normsthename]

I tried opening it, but my Excel won't open it for some reason
Could someone do me a quick calculation
I am upgrading my Homebuilt Plasma by extending the table, this is the design so far
The Y Axis has two unsupported solid rails @1500mm long (See Picture) the centre bar is the Ballscrew.
I still need to add some form of aluminium extrusion to stiffen up the Y Axis Gantry.
It has the Z Axis assembly hanging off of it and also the Plasma torch, not sure what that will weigh.......
I think I might need to put some form of support under the rail, I had to do that on my first machine, I had small angles welded at 45° under the rails, and setscrews to bear onto the rail

Thanks in advance

Andy