Why not follow the Hustler with another record-breaking air cutter? Here's a walk around the SR-71, the fastest manned air-breathing plane (about 2,200 mph) also holds the record for sustained altitude in horizontal flight (about 85,000 feet), both records set in 1976. This one is the second built and the oldest in existence. It was also the only aircraft in the Blackbird family to be designated YF-12C. Why? NASA was testing the effects of flight at speeds and altitudes only the Blackbird could