Below is one of the diagrams that I used to help create “Lockheed SR-71: Origins and Evolution.” It is a Lockheed diagram taken from a CIA report showing the D-21 drone atop an M-21 mothership… basically a two-seat version of the A-12 spyplane. The D-21 program as a whole was a dismal failure, but launching it from the back of a manned Mach 3 aircraft proved to be fatal. Still, the D-21, for all the trouble it had, was an impressive piece of work; had there been more of a drive to make it work, doubtless Lockheed would have made it into a successful recon platform. But the time, effort and expense just didn’t compare well to results from spy satellites, and the program was ended. A number of airframes have been preserved, and there have been attempts to resurrect them for use as experimental platforms.
The full-rez diagram has been uploaded to the 2022-01 APR Extras folder on Dropbox. This is available to all $4 and up Patrons and Subscribers. If you would like to help fund the acquisition and preservation of such things, along with getting high quality scans for yourself, please consider signing on either for the APR Patreon or the APR Monthly Historical Documents Program.
I plan on uploading a number of the diagrams, art and whatnot that I used to create the CAD diagrams in “SR-71” the the APR extras Dropbox in the coming months.