|Firebomber KC97 N1365N of Hawkins and Power at its base in Greybull, Wyoming|
|Boeing began work on a transport aircraft to take
advantage of the new technology introduced on its B-29 Superfortress
The USAAF ordered three XC-97 prototypes, called the model 367 by Boeing, and these used as many parts as possible from the long range heavy bomber but with a new pressurised fuselage.
While Boeing worked on the military version, engineers also looked into a version intended for post-war use as a civil transport, the 377. Little work was done on this type until after VJ Day, by which time the XC-97 had flown, on November 15, 1944.
The C-97 was named Stratofreighter and 50 C-97A transports were built for the USAF, along with 14 aeromedical aircraft. But the programme really escalated when the KC-97 was chosen as a flying tanker. Sixty KC-97Es were followed by 159 KC-97Fs and then 592 KC-97Gs. Many Gs became Ls with jet boosters under the wings and the type operated into the 1970s, also serving with the Spanish Air force. Several aircraft later joined the civil market as freighters.
Meanwhile, for the civil version Pan Am encouraged the fitting of the new Pratt and Whitney Wasp Major engine and the aircraft that emerged in 1946 featured this powerplant and numerous advanced features, such as full airframe de-icing.
But by far the most innovative feature was the large double-bubble cross-section fuselage that allowed room for 100 passengers and a spiral staircase down to a bar and lounge.
Pan Am ordered 20, which it called Stratocruiser, with further orders coming from BOAC, Northwest, American Overseas and United. SAS also ordered four but never took delivery, these aircraft going to BOAC, which eventually operated 17. United and Northwest had their aircraft built to a slightly different standard and they could be distinguished by their square, instead of round, windows. Nearly all the airlines fitted some folding sleeping bunks.
Total production of the 377 only reached 55, with most operators scared off by the complex engines. The original operators, indeed, did face many technical problems with their fleets but the type soon became popular on long distance routes in the early 1950s. The most important of these was the Transatlantic crossing, where Pan Am and BOAC competed for passengers. Both airlines installed extra fuel tanks to make the trip non-stop.
The 377 enjoyed only a limited reign, being replaced by jets from the mid 1950s. Noteable operators of secondhand machines included RANSA of Venezuela, which used three for all-cargo operations, and Transocean, which kept ten in service until 1963. The Israeli Air Force also operated five Stratocruisers converted as tankers, transports and electronic warfare aircraft.
The basic type enjoyed a new lease of life when Aero Spacelines used it as the airframe for its Guppy outsized load transporters.
The only aircraft still flying of any of the various marks is a C-97 of the Berlin Airlift Historical Association in the USA.