Named RAT55, the U.S. Air Force Materiel Command’s plane just flew across the country, making two stops -- one in Arkansas and one in Texas.

The A-12 Oxcart, developed by Lockheed’s Skunk Works for the CIA in the early 1960s, was the single-seat, Mach 3.29 (at 90,000 feet) precursor to the USAF’s more famous SR-71 Blackbird. -While both ...