KerbalX

The D-21 was a drone developed after the U-2 incident to be a safer alternative for crew reconnaissance flights. It would fly over the target, take photographs then fly to a safe area to drop the film and finally self-destruct. It was initially launched on a M-12 (modified A-12) but after a fatal crash where the drone crashed into the mothership after launch, the B-52 was used as a mothership. The drone program was later cancelled due to several failed missions and the fact that the A-12 (and later SR-71) were just as suitable for the job.

Flight instructions:
Take off the M-12 and get to your desired altitude. To deploy the drone from the mothership, first turn on the engines with staging, when at full thrust, stage again to deploy. When done the mission, activate abort (backspace) to self-destruct!

The page for the A-12 : https://kerbalx.com/LeRossignol/A-12-Oxcart

There are two versions you can download:
-The D-21 mounted on a M-12
-The D-21 by itself (with landing gear)