Republic RC-2 Rainbow
Developed in 1943 the Republic XF-12 Rainbow was meant as a fast long range reconnaissance aircraft. It was the fastest large aircraft of its time. Because of the end of the war it did not enter into production however.
Republic had always intended to also build an airline version of the aircraft to be known as the RC-2. Fuel capacity would have been increased, and more powerful (at lower altitude) P&W R-4360-59s were substituted in place of the P&W R-4360-31s on the U.S. Air Force version.
The aircraft was lavishly appointed for the 46 passengers and seven crew. It was fully pressurized to sea level, air conditioned, with an electric galley providing hot meals and with an inflight lounge. It had the ability to cruise above the weather at 435 mph at 40,000 feet.
The launch customer for the RC-2 Rainbow was American Overseas Airways who operated the rainbow on their route from New York to London from 1945 onwards. The aircraft could fly this route non-stop at a cruise speed of 400mph making the crossing a lot faster than the Douglas DC-6 which had to make a stop en route and had a much lower cruise speed.
The Rainbow served with a large number of airways and was only replaced by the jet engined DC-8 and Boeing 707 in the early 1960s.