There's been a lot of talk about this where I used to live. When the -117 and B-2 were being developed Lockheed, Northrop and I am told General Dynamics (before Lockheed bought them) all experimented with proof of concept aircraft. We know about "Have Blue" and the Northrop "Flying Bath Tub" but never heard anything else. Additionally the same thing was done by Grumman on the ill fated A-12.
If the grainy photos are real, I suspect that's what they are.