of a cabin pressure regulator. In 1932, Boeing had introduced the fast, all-metal Model 247, considered the first modern commercial airliner. It was a leap ahead of the competition, but its success was brief, as Douglas Aircraft quickly developed a challenger with the DC-2 and followed with the legendary DC-3. Faced with being shut out of the commercial airplane market, Boeing had to design the next leap in air travel. Fortunately, Boeing had already developed the Model 299, a giant four-engine bomber that would become the B-17 Flying Fortress. The successful design of the B-17 became the basis for a new commercial airplane that would be that great leap: the Model 307. The new airplane combined the wings and tail surfaces from the B-17 with a cigar-shaped fuselage purposely designed to be a pressure vessel. Not only would its size, four engines and long range be a market advantage, but the addition of cabin pressurization would allow Boeing to market an airplane that could fly passengers higher than 20,000 feet (6,100 meters)—“above the weather.” To reflect this capability Boeing named the Model 307 the Stratoliner. Orders for the plane came in from Pan American Airways and TWA. Hughes also ordered a Stratoliner for his attempt at a world speed record. On New Year’s Eve in 1938, the Stratoliner prototype took off from Boeing Field near Seattle on its inaugural flight. Tragically, that prototype and a crew of 10 would later be lost in an airline demonstration flight. A second prototype flew June 20, 1939. Less than a month later, Hughes took delivery of the first production airplane. Hughes wanted the Model 307 for an around-the-world flight that would break his own record of 91 hours 14 minutes set between July 10 and July 14, 1938, in a Lockheed 14. His Stratoliner was fitted with extra fuel tanks. But the attempt never happened due to the outbreak of World War II. Instead, Hughes transformed his Stratoliner into a “flying penthouse” and it was later sold to an oil tycoon. The Stratoliner had a crew of five and could carry 33 passengers in day flights and 25 at night, with seating that reclined or converted into berths. While most commercial passenger flights at the time were limited to 10,000 feet (3,000 meters), the pressurized cabin of the 307 allowed it to fly at more than 20,000 feet (6,100 meters) and maintain a comfortable temperature in the cabin. But the Stratoliner’s success was short-lived. With the outbreak of war, Boeing turned to a maximum effort to build bombers and ended production after just 10 airplanes. During the war, Stratoliners were drafted into military service and made thousands of accident-free crossings of the Atlantic serving as VIP transports. Only two Stratoliners remain: Howard Hughes’ personal Stratoliner is now a houseboat and continues to be a popular attraction in Florida; the last flyable 307, Pan Am’s Clipper Flying Cloud, was fully restored by Boeing and delivered in August 2003 to the National Air and Space Museum, where it is on display at the Stephen F. Udvar-Hazy Center in Chantilly, Va. n michael.j.lombardi@boeing.com PHOTOS: (Far left) Following a restoration by Boeing, the last flying Stratoliner, Pan American Airways’ Clipper Flying Cloud, flies near Mount Rainer in Washington state. (Insets, from left) On the left of the Stratoliner’s cabin were nine single seats that could fully recline for overnight flights; the right had four compartments with seating for six pas-sengers each; for overnight flights, seating would convert to sleeping berths. BOEING ARCHIVES BOEING FRONTIERS / DECEMBER 2013–JANUARY 2014 13
Frontiers December 2013—January 2014 Issue
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