Finding a D21 drone in an aircraft graveyard

Anything related to SR-71 is amazing, especially this D21 drone that rode on top of a modified blackbird at Mach 3!!!

I'm a bit confused by this story. He says he found it 'abandoned' in the backlot of some AZ aircraft graveyard in 2009, but it was actually loaned to the Pima Air Museum in ... 1993.

https://flic.kr/p/nHrFJm

It was on their lot, it just wasn't on display at that time. Probably because there were already eight others ( plus some wrecakge ) on display around the USA... Despite its secrecy it's not a rarity.

Also the serial he states is incorrect, 90-0533 is a USAF C-17A transport; the 90 indicates the Fiscal Year in which the procurement was authorised. That D-21's serial was just a non-standard 533. Like a lot of the A-12 / SR project things weren't always booked and accounted like they should have been.

Is this a similar concept as the cancelled Soviet Lavochkin La-350 ramjet cruise missile design of the 50's, which was based on ideas of a German Dr. Wolf Trommsdorf (who was working for the Russians after the WW2)?

https://en.wikipedia.org/wiki/Burya

edit: a bit more info (German only, sorry) http://www.fliegerrevuex.aero/mach-35-interkontinentalflugko...

There's a well preserved one mounted on the M-21 at the Museum of Flight in Seattle.

http://www.museumofflight.org/aircraft/lockheed-d-21b-drone

It seems the drone had been moved to that back lot at some point. The last time I was at Pima that drone was in a hanger with other unmanned aircraft.