BrightStar was a quiet supersonic demonstrator, internally funded in the late 90s.
I know there's something over at DLR about this, but is there anything else?
I've seen LM docs that depict an aircraft very much like the "SST" seen on the runway on DLR, and *could* match the in flight photo. Two persons at LM who would be in the know independently mentioned a quiet supersonic project that was in the works during that period. LM felt that quiet supercruise may become a requirement in the 00's, and that was at least one reason they pursued it. I was told that they did not think they could develop the technology without flight test.