Where do you test out scramjets, transatmospheric space planes and wave riders? In the supersonic wind tunnel at Tennessee's Arnold Air Force Base, that's where.

You can see just how epically large this thing is by the little man standing next to one of the fan blades, a place you wouldn't want to be anywhere near once this thing is set in motion. I sort of half-expect a portal to another dimension to open up when it hits full speed.

See it full-size by clicking the image below.

Arnold AFB, via Gizmodo