abstract
| - The 314 was a response to Pan American's request for a flying boat with unprecedented range capability that could augment the airline's trans-Pacific Martin M-130. Boeing's bid was successful and Pan American signed a contract for six aircraft on 21 July 1936. Boeing engineers adapted the cancelled XB-15's 149 foot (45.5 m) wing, and replaced the original 850 hp (640 kW) Pratt & Whitney Twin Wasp radial engines with the more powerful 1,600 hp (1,194 kW) Wright Twin Cyclone. The Clipper's triple tail was chosen after Boeing tested conventional and twin tails which did not provide enough controllability for safe flight. Internally, the 314 used a series of heavy ribs and spars to create a robust fuselage and cantilevered wing. This sturdy structure negated the need for external drag-inducing struts to brace the wings, something other flying boats of the day could not boast. Boeing addressed the flying boats' other drag-inducing issue, stabilizing pontoons, by incorporating sponsons into the hull structure. The sponsons, which were broad lateral extensions placed at the water line, on both the port and starboard sides of the hull, served several purposes: they provided a wide platform to stabilize the craft while floating on water, they acted as an entryway for passengers boarding the aircraft and they were shaped to contribute lift while the aircraft was in flight. To fly the long ranges needed for trans-Pacific service, the 314 carried 4,246 US gallons (16,100 L) of gasoline. The later 314A model carried a further 1,200 US gallons (4,540 L). To quench the radial engines’ thirst for oil, a capacity of 300 US gallons (1,135 L) was required. Pan Am's "Clippers" were built for luxury, a necessity given the long duration of transoceanic flights. The seats could be converted into 36 bunks for overnight accommodation; with a cruise speed of only 188 mph (300 km/h), many flights lasted over twelve hours. The aircraft had a lounge and dining area, and the galleys were crewed by chefs from four-star hotels. Men and women were provided with separate dressing rooms, and white-coated stewards served five and six-course meals with gleaming silver service. Although the transatlantic flights were only operated for three months in 1939, their standard of luxury has not been matched by heavier-than-air transport since then; they were a form of travel for the super-rich, at $675 return from New York to Southampton, comparable to a round trip aboard Concorde in 2006. Equally critical to the 314's success was the proficiency of its Pan Am flight crews, who were extremely skilled at long-distance, over-water flight operations and navigation. Only the very best and most experienced flight crews were assigned Boeing 314 flying boat duty. Before coming aboard, all Pan Am captains as well as first and second officers had thousands of hours of flight time in other seaplanes and flying boats. Rigorous training in dead reckoning, timed turns, judging drift from sea current, astral navigation, and radio navigation were conducted. In conditions of poor or no visibility, pilots sometimes made successful landings at fogged-in harbors by landing out to sea, then taxiing the plane into port.
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