I dont know why you would think you would start a war.
As for the math I put on some thread here how to do this with a drawing but I cant find the drawing.
Is is very very easy.
Here is the so called math.
If you want a 12 foot tall hoop then you will have to have a little over 37 feet of pipe.
That half circle is called the radius so a circle with a 12 foot radius is 24 feet in diameter.
The 24 feet will be multiplied by 3.14.
This will give you 75.36 this is the circumference.
Divide 75.36 by 2 and you get 37.68.
Now to get that on a plywood form all you need to do is take string a screwdriver or what ever and a pencil and use it as a gig compass.
Look for tubing rollers.
Worth