The Boeing Stratocruiser was the largest and most luxurious airliner of its time. Passengers loved it, but it still failed as a commercial transport. Its mainline service career lasted only a decade, thanks to the one-two punch of eye-watering operating costs and the arrival of the more efficient Boeing 707. It didn’t help that the Stratocruisers’ high-tech propellers often tore themselves loose from the engines, leaving the worldwide fleet with a stupefying accident record. Of the 56 Stratocruisers Boeing built, Pan American Airways alone lost seven—almost one a year between 1952 and 1959. United, Northwest Orient and BOAC each crashed one. Surviving Strats ended up being sold for scrapyard prices. But those junked airplanes led to the development of a remarkable new category of aircraft known as volumetric transports—or, more familiarly, Guppies.
Boeing called the Stratocruiser the Model 377, and its lineage led from… well, nits are painstakingly picked over this issue. Many say that the roots of its family tree were fertilized by the B-29 Superfortress, or at least the later B-50 version, which used the R-4360 engines that would power the Stratocruiser. Others point to Boeing’s double-deck C-97 Stratofreighter and its aerial-refueling tanker version, the KC-97. (To Boeing, these two B-50 derivatives were called Model 367s.) Conventional 1940s aeronautical engineering theory held that there was a limit to an airplane’s fuselage diameter relative to wingspan and powerplants, so most aircraft were designed with a small fuselage and large wings. The porcine Douglas C-124 Globemaster II, the first big postwar transport, pushed fuselage diameter to the max that convention would allow. The C-97, however, pushed things even further.
Some Boeing nerds nominate a single modified Model 367 as the Stratocruiser’s daddy. It was a C-97 that had been fitted out as a
