September 1, 1948: XR-12 Rainbow Makes Cross-Continental Flight

A Republic XR-12 Rainbow took off from Edwards, flew out over the Pacific, and then made a nonstop coast-to-coast flight to New York. Along the way it made a single, 325-foot-long filmstrip recording its entire flight path across the continental United States. This was the first time that a portrait of this magnitude had ever been made. The XR-12 was the peacetime designation of the XF-12, an experimental high-speed four-engine reconnaissance plane of exceptional capabilities

The Republic XF-12 Rainbow was an American four-engine, all-metal prototype reconnaissance aircraft designed by the Republic Aviation Company in the late 1940s. Like most large aircraft of the era, it used radial engines, in this case, the Pratt & Whitney R-4360 Wasp Major. The aircraft was designed with maximum aerodynamic efficiency in mind. The XF-12 was referred to as an aircraft that was "flying on all fours" meaning: four engines, 400 mph cruise, 4,000 mile range, at 40,000 feet.It is still the fastest piston-engined airplane of this size, exceeding by some 50 miles per hour the Boeing XB-39 of 1944.  Although highly innovative, the postwar XF-12 Rainbow had to compete against more modern jet engine technology, and did not enter production.