Boeing 377 Stratocruiser

Design and development

The Boeing 377 Stratocruiser was a civil derivative of the Boeing Model 367, the Boeing C-97 Stratofreighter, which first flew in late 1944. William Allen, who had become president of the Boeing Company in September 1945, sought to introduce a new civilian aircraft to replace reduced military production after World War II. Boeing saw in their large-bodied, fast, and long-ranged military transport potential for a passenger aircraft suited for premium service on long transoceanic routes, expanding on the precedent set by their Boeing 314 Clipper with Pan American World Airways. Despite a recession in late 1945, Allen ordered 50 Stratocruisers, spending capital on the project without an order from an airline customer.

On 29 November 1945, Pan American World Airways (Pan Am) became the launch customer with the largest commercial aircraft order in history, a $24.5 million order for 20 Stratocruisers. Earlier in 1945, a Boeing C-97 had flown from Seattle to Washington, D.C. nonstop in six hours and four minutes; with this knowledge, and with Pan Am President Juan Trippe's high regard for Boeing after their success with the Boeing 314 Clipper, Pan Am was confident about ordering the expensive plane.

The 377 shared the distinctive design of the C-97, with a "double-bubble" fuselage cross-section, resembling a figure-8, with the smaller loop on the bottom, and 6,600 cubic feet (190 m3) of interior space shared between two passenger decks. Outside diameter of the upper lobe was 132 inches (340 centimeters), compared to 125 inches (320 centimeters) for the DC-6 and other Douglas types (and 148 inches or 380 centimeters for today's 737). The lower deck served as a lounge, seating 14, earning it the nickname of "Stratoboozer." 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. In all, 4 million man-hours went into the engineering of the 377. It was one of only a few double-deck aircraft ever built for commercial use, another being its French contemporary, the Breguet Deux-Ponts, as well as later models, the 747 and the Airbus A380.

The first flight of the 377 was on 8 July 1947, two years after the first commercial order. The flight test fleet of three 377s underwent 250,000 mi (217,000 nmi; 402,000 km) of flying to test its limits before certification.

Other carriers who adopted the Stratocruiser were British Overseas Airways Corporation, American Overseas Airlines (merged with Pan Am in 1950) and United Airlines. The last 377 was delivered to BOAC in May 1950. On this delivery flight, Boeing engineer Wellwood Beall accompanied the final 377 to England, and returned with news of the de Havilland Comet, the first jet airliner, and its appeal. The tenure of the Stratocruiser with United ended in 1954, when United had the opportunity to sell them to BOAC after finding them unprofitable without the extra mail subsidies enjoyed by Pan Am and Northwest.

Only 56 were built, one prototype (later reconditioned) and 55 production aircraft. As a result of low production volume, Boeing lost $7 million on the aircraft.

Operational history

As the launch customer, Pan Am was the first to begin scheduled flights, from San Francisco to Honolulu in April 1949. At the end of 1949, Pan Am, BOAC and American Overseas Airlines (AOA) were flying 377s transatlantic, while Northwest Orient Airlines was flying in the United States; in January 1950, United began flights from San Francisco to Honolulu. Stratocruisers were pressed into emergency military service after the onset of the Korean War. In late 1950, Northwest Stratocruisers were serving New York City, Chicago, Detroit, Minneapolis/St. Paul, Milwaukee, Spokane, Seattle, and Honolulu.

By late 1952, Northwest Stratocruisers replaced DC-4s to Tokyo via Anchorage, Alaska; Northwest replaced the Stratocruiser on the Honolulu run in 1953 and to Tokyo in 1955. For a short time, Pan Am 377s flew to Beirut, Lebanon, but after 1954, no 377 was scheduled east of Europe or west of Singapore. In 1954, United Stratocruisers flew Los Angeles to Honolulu and between Seattle and San Francisco; United's B377 flights to Honolulu were all first class. In 1955, BOAC 377s had 50 First Class seats (fare $400 one way New York to London) or 81 Tourist seats (fare $290). In 1956, Pan Am 377s flew from Los Angeles and San Francisco to Sydney with stops at Honolulu, Canton Island and Suva (via Nadi Airport in Fiji).

By 1958, Pan Am was operating the Stratocruiser between Seattle, Washington and Fairbanks, Juneau and Ketchikan, Alaska and between Seattle and Whitehorse, Yukon. Within six years of first delivery, the Stratocruiser had carried 3,199,219 passengers; it had completed 3,597 transcontinental flights, and 27,678 transatlantic crossings, and went between the United States and South America 822 times.