Yes I remember this structure from a documentary on the WW2 Nazi German Horten 229 jet fighter/bomber that was recreated by Grumman/LM(?) technicians and this was taken to classified USAF facility where jet/drones were hoisted on top of structures like this and subjected to radars of all types to determine RCS-interestingly they did not reveal the Horten's RCS but stated it was well ahead of its time and used properly(destroying RAF radar stations in a stealthy first strike and would be uncatchable(900-1000km/hr!!!) by the RAF's piston engined planes)amazing.
There are a few inaccuracies here.
The Horten was only a prototype and never made it to production.
The Germans did not understand or aim for RCS reduction during that era. It was a totally happy coincidence that the flying wing was also a airframe design that is conducive to RCS reduction. This wasn't the objective of the flying wing when it was envisaged by the Horten brothers or Jack Northrop.
Northrop was actually the first to experiment with flying wing, before the Hortens. Look up the N1M.
Some American company did eventually do a replica of the Horten and tested its RCS, it was nowhere near a stealth aircraft, proving they didn't design the Horten prototype based on any science of RCS reduction.
