Lockheed YF-12. A missile-armed interceptor version of the A-12. It is the largest and fastest interceptor aircraft ever built. (Ca. 1963) : r/WeirdWings
Air Force Mach-3 YF-12 Interceptor Story
YF-12 | Military Wiki | Fandom
Lockheed YF-12 - Wikipedia
What is the difference between the SR-71 and the YF-12? - Quora