The blog containing this post is no longer active but can be accessed on
Web Archive.
"SR-91" is a made-up designation invented by a netizen, and the codename Aurora referred to requested funds in a 1985 Pentagon budget request for B-2 program support/logistics (e.g. AIRSAR development). When news articles reported on the Pentagon budget request mentioning Aurora, there was speculation that Aurora had to do with either the F-117 or B-2. The name Aurora became associated with a reputed hypersonic successor to the SR-71 beginning in the late 1980s because when a number of black aircraft gurus noticed that Aurora was mentioned above a line item for the U-2 in the 1985 Pentagon budget request, they suggested that Aurora referred to an SR-71 replacement.
The "donuts-on-a-rope" contrails once touted by Bill Sweetman and a few other people as tantalizing evidence for the existence of a hypersonic replacement for the SR-71 are actually contrails made by airliners.
No operational hypersonic replacement for the SR-71 existed in the early 1990s, but Lockheed and Boeing did work out designs for hypersonic spyplanes in the late 1970s and 1980s, which remained on the drawing board.
