In May 1946, the Rainbow set a new cross-country speed record for four-engined aircraft, covering 576 miles between New York and Wright Field at 426 miles per hour. A Lockheed Constellation had held the previous record of 375 miles per hour.
On Nov. 4, 1948, this mission-equipped second ship experienced an explosion in its number two engine nacelle, which gave Hendrix and the others in his three-man crew no choice but to hit the silk. Flight testing of ship number one was suspended.
Earlier, with a postwar boom in air travel envisioned by many, Republic negotiated with American Airlines for the purchase of 20 RC-2 Rainbow civilian variants for use on high-speed passenger runs. In 1946, Pan American World Airways issued a letter of intent to purchase six RC-2s with options on a dozen more.
The XR-12 had a wingspan of 129 feet 2 inches. The pointy fuselage was 99 feet 8-1/4 inches long. Empty weight was 66,980 pounds and when fully grossed the Rainbow weighed 113,250 pounds. It was bigger and roomier than it looked. Republic envisioned the RC-2 airliner as carrying 46 passengers up to 4,100 miles at a cruising speed of 410 miles per hour. The military XR-12 had a maximum speed of 460 miles per hour at 28,000 feet, making it comparable in speed with the final propeller-driven fighters in inventory, planes like the F-51H Mustang and F8F-2 Bearcat.
Even when tests of the competing Hughes aircraft were ended – the XR-11 (earlier, the XF-11) had also been built in two prototypes and one had crashed, almost killing pilot Hughes – the Air Force (which emerged from the AAF to become an independent service branch on Sept. 18, 1947) in 1948 stood by the XR-12. The airlines were first to waver, perhaps because new-built, post-war Douglas DC-4s were coming off the production line, with DC-6s soon to follow.
The loss of the working second prototype ended the Air Force’s support and was the death knell for the “might have been” XR-12 Rainbow. Several years before President Dwight D. Eisenhower’s proposal for an “Open Skies” exchange with the Soviet Union, the project was shelved. At one point, an order had existed for 20 R-12As, but was diverted to RB-50 Superfortresses. When the project was canceled, a further production order for six R-12A Rainbows was canceled, too.
The prototype in all of its elegant glory was placed into storage. And then, this beautiful and promising aircraft was carted off to Aberdeen Proving Ground, Maryland, where it was used as an artillery target and destroyed.