Warplanes of the USA: Republic XF-12 Rainbow

Republic XF-12 Rainbow

(USAAF Photo)

Republic XF-12 Rainbow (Serial No. 491002).

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, specifically the Pratt & Whitney R-4360 Wasp Major. The XF-12 was referred to as "flying on all fours" meaning: four engines, 400 mph (640 km/h) cruise, 4,000 mi (6,400 km) range, at 40,000 ft (12,000 m). The aircraft was designed to maximize aerodynamic efficiency. Although innovative, the jet engine and the end of the Second World War made it obsolete, and it did not enter production. A proposed airliner variant, the RC-2, was deemed uneconomical and cancelled before being built. (Wikipedia)

(USAAF Photo)

Republic XF-12 Rainbow, (Serial No. 491002).

The XF-12's first flight was made on 4 February 1946 and during flight testing, it reached an altitude of 45,000 ft (14,000 m) at 470 mph (760 km/h), and demonstrated a range of 4,500 mi (7,200 km), exceeding design criteria. The XF-12 could photograph in both daylight and night and under conditions of reduced visibility at high altitudes over long ranges and with great speed. This "flying photo lab" was capable of mapping broad stretches of the globe. he XF-12 was the fastest aircraft of its day to use four reciprocating engines, and the only one to exceed 450 mph (720 km/h) in level flight.The first prototype was damaged on 10 July 1947 while undergoing maximum landing weight tests when the right main gear was severed at the engine nacelle. On 7 November 1948, the second prototype crashed while returning to Eglin Air Force Base from a photographic suitability test flight after the number 2 (port inner) engine exploded, causing violent buffeting. Five of the seven crew escaped safely while two crew members were killed.

The first prototype continued flight testing after being returned to service in 1948 but with no orders forthcoming and with the second prototype lost, flight testing was wound down and the remaining prototype was retired in June 1952, having flown just 117 hours from 1949 to 1952. It was later expended as a target at the Aberdeen Proving Ground, Maryland. (Wikipedia)

(USAAF Photo)

The first Rainbow takes off from Republic Field in Farmingdale, N.Y. Note ample flaps, which extended along 60 percent of the wingspan.

The first prototype was damaged on 10 July 1947 while undergoing maximum landing weight tests when the right main gear was severed at the engine nacelle. After bouncing hard and staggering back into the air the test pilot climbed to a safe altitude where excess fuel was burnt off, to lighten the aircraft and reduce the risk of fire. The pilot landed on the left main gear and the nose wheel and despite losing as much speed as possible before the other wing dropped, the aircraft suffered significant damage. The wing spar was cracked, and engines and props needed to be replaced but it was repaired by Republic, and returned to service. When the U.S. Army Air Forces became the U.S. Air Force the XF-12 was later re-designated XR-12. (Wikipedia)