I like a bit of conspiracy with my tea, but having been there a few times over the years, the stories around Machrihannish are laughable. More likely to be raised by sad people counting on the fact that it's out of the way and most folk won't take the trouble to make the trip.
Anyway, back on to real things, one good thing to come out of this thread was finding something I thought long forgotten from the 50s and 60s, the Valkyrie XB-70:
Like the SR-71, Mach 3+ cruise capable, but also able to carry a 50,000 weapons payload, a range of 7,500 miles, and a flight deck that doesn't require the crew to wear spacesuits.
Clearly larger than the SR-71, the XB-70 housed 6 special engines to achieve her performance, but more interesting is that it was developed about the same time as the the A-12 (predecessor to the SR-71) and the construction and operating principles are completely different. Much of the construction is of a stainless steel honeycomb (so thin, it was describes as tinfoil) rather than expensive titanium. The SR-71 used all they had in America then anyway, and they had to import more. In flight, the outer part of the wing folded down in stages, reducing drag and increasing lift using an effect known as compression lift.
Unlike the SR-71, it wasn't a secret, and was seen, supersonic, at airshows.
After a stupid midair collision (basically during a photo shoot) in 1966 killed one crewmember, the pilot of an F-104 escort, and destroyed one of the two aircraft, the Air Force finally pulled out of the program in 1969, and the remaining aircraft was hangared the Dayton Air Force Musuem.
The site
http://www.labiker.org/xb70.html is worth a long browse, containing not only the story, but a photo gallery and links to archive footage of the Valkyrie in action.