That’s what you get when you’re replicating 50-year-old American stuff! 
You like that new stuff, don’t you?
It would be nice to have access to the U.S. Army’s original blueprints, as they’re metric; everything I have to work with is in inches, and it’s kinda pointless introducing another layer of inaccuracy by converting to metric. 
You know you can use a metric template in SketchUp and type values in inches and it converts it for you. (And vice versa: You can use an inches template in SketchUp for making cabinets, and enter mm for the European hinge hardware.)
Entity Info displays the area of the face, not of the circle. Naturally the number of segments affects the area. Everybody already knows that SketchUp is a face modeller and not NURBS-based. When modelling, that must be taken to account. Of course one would like to see a NURBS SketchUp, but that would probably require the application to be totally rewritten.
You probably mean this:
My brain is locked in Imperial now. There’s only so much it can take.
It could be argued that this is allegory. Not comedy. And everyone knows that allegory is not as precise as argumentation. ;^)
OK, I’m outta here. 
I also design parts using SketchUp. With the exception of creating multiple fillets in SketchUp, I have no trouble designing precision parts with it, and I am still doing so.
Very nice work. Good presentation, too.
I have to admit that your drawings were the inspiration, Dave!
Aw, shucks. Thank you!
It’s pure " techno art ", if that name even exists!
It does now.
People claim these kinds of models are difficult to create with SketchUp, but wait 'til they have to draw the cavity that results from intersecting an asymmetrical spheroid with the side of a cone! 