Summary and 3 Points You Need to Know: The YF-12A, developed by Lockheed Martin’s Skunk Works in the early 1960s, was a pioneering aircraft that combined early stealth features with unmatched speed.

Here’s What You Need to Remember: The last remaining YF-12 saw continued use, however, in joint supersonic cruise testing between NASA and the U.S. Air Force, until it was ultimately retired to the ...