As it screams through the air at three times the speed of sound, this jet needs to keep the air flowing through the engines down around 500 mph. The solution: a retractable cone plus a series of doors and bypasses. Pilots monitor this system on a sub-panel of indicators (lower left) while making sure they hit specific speeds at precise altitudes during ascent and descent. This Cold War-era spy jet, retired in 1998, also collected intelligence on itself, with a sort of proto-black box that captured 200-plus data points every three seconds. “If a pilot screwed up, we could download the tapes and say, ‘OK, buddy, here’s what you did wrong,’” says Rich Graham, a flight instructor and retired SR-71 pilot.