reply to post by TheOven
Radar cross section measurement is at the heart of stealth technology. The idea is to determine how "large" your shape will appear to radar.
Engineering comes up with a shape, presumably with a lot of computer simulation these days. Obviously the shape has to fly most of all, else you have
a stealthy lawn dart. But right up there with a suitable aerodynamic shape is the ability for the plane to have a small radar return. The usually
measure it in decibells.
Once you have the shape, it makes sense to create a mockup to see how it will look on radar. [This is far cheaper than building the real thing, only
to find it doesn't work as planned.] The shape is the "pole model". The shape is placed on a pole (pylon), then it is pinged with radar from a
dish. Hence the RCS facility has a collection of dishes on one side, a bit of space, and then a pole on the other. This is known as static RCS, since
the model isn't moving. [There is also dynamic RCS, which I believe is always tested on the real thing since it has to be flying to be tested.]
Northrop has Tejon Ranch. Lockheed has a similar, though a bit larger facility in Helendale. It was shown in the PBS Nova "Battle of the X-planes".
This is the producer's notes as he approached the pylon at Helendale. That pylon has an underground chamber, so the model can be set up in
"privacy" and presumably tested at night.
In the distance I can see a huge man-made crater. We soon come to the lip of the "hole." Fifty feet below is what looks like a missile silo—a
concrete bunker about half the size of a football field with a pair of massive doors on top. As I set up my camera, my escort radios some orders over
his walkie-talkie. The doors suddenly slide open and brilliant red light streams out. I feel like I'm on the set of "Close Encounters of the Third
I have a panorama of the Helendale site here.
You can just barely see the "cavern". It is possible to get a better view (higher elevation), but I was pressed for time when I shot it.
Howland has a good write up on RCS measurement.