The Stratocruiser's first flight was on July 8, 1947. Its design was advanced for its day; its innovative features included two passenger decks and a pressurized cabin, a relatively new feature on transport aircraft. It could carry up to 100 passengers on the main deck plus 14 in the lower deck lounge; typical seating was for 63 or 84 passengers or 28 berthed and five seated passengers. The Stratocruiser was larger than the Douglas DC-6 and Lockheed Constellation and cost more to buy and operate. Its reliability was poor, chiefly due to problems with the four 28-cylinder Pratt & Whitney R-4360 Wasp Major radial engines and structural and control problems with their propellers. Only 55 Model 377s were built for airlines, along with the single prototype. The 377 shared the distinctive design of the C-97, with a "double-bubble" fuselage cross-section, resembling an inverted figure-8, with 6,600 ft³ (187 m³) of interior space shared between two passenger decks. Outside diameter of the upper lobe was 132 inches, compared to 125 inches for the DC-6 and other Douglas types (and 148 inches for today's 737). The lower deck served as a lounge, seating 14. The 377 had innovations such as higher cabin pressure and air conditioning; the superchargers on the four Pratt & Whitney R-4360 engines increased power at altitude and allowed constant cabin pressure. The wing was the Boeing 117 airfoil, regarded as the "fastest wing of its time". In all, 4,000,000 man-hours went into the engineering of the 377. It was also one of but a few double deck airliners, another being its French contemporary, the Breguet Deux-Ponts, as well as Boeing's own 747 and the Airbus A380. A total of 56 were built, one prototype (later reconditioned) and 55 production aircraft. Aero Spacelines Guppy A company called Aero Spacelines was converting old 377s to aircraft called Guppys in the 1960s. There were three types: the Pregnant Guppy, Super Guppy, and Mini Guppy. They had an extension to the top of the fuselage to enable them to carry large aircraft parts between manufacturing sites. The first was the Pregnant Guppy, followed by the Super Guppy, and finally the Mini Guppy. The Super Guppy and the Mini Guppy had turboprop engines. For more details of the development,design,operational history of the 377 and its 10 variants, as well as the Guppies, click here.
