Design and development
Pan American had requested a flying boat with unprecedented range that
could 
augment
the airline's trans-Pacific Martin M-130. Boeing's bid was successful and
on July 21, 1936, Pan American signed a contract for six. Boeing engineers
adapted the cancelled XB-15's 149 feet (45 m) wing, and replaced the 850
horsepower (630 kW) Pratt & Whitney Twin
Wasp radial
engines with the 1,600 horsepower (1,200 kW) Wright Twin
Cyclone. Pan
Am ordered six more aircraft with increased engine power and capacity for
77 daytime passengers as the Boeing 314A.
The huge flying boat was assembled at Boeing's Plant 1 on the Duwamish River and towed to Elliott Bay for taxi and flight tests. The first flight was on June 7, 1938, piloted by Edmund T. "Eddie" Allen. At first the aircraft had a single vertical tail, and Allen found he had inadequate directional control. The aircraft returned to the factory and was fitted with the endplates on the ends of the horizontal tail in place of the single vertical fin. This too was found to be lacking and finally the centerline vertical fin was restored, after which the aircraft flew satisfactorily.
The 314 used a series of heavy ribs and spars to create a robust fuselage and cantilevered wing, obviating the need for external drag-inducing struts to brace the wings. Boeing also incorporated Dornier-style sponsons into the hull structure. The sponsons, broad lateral extensions at the waterline on both 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 flying boat and they were shaped to contribute additional lift in flight. Passengers and their baggage were weighed, with each passenger allowed up to 77 pounds (35 kg) free baggage allowance (in the later 314 series) but then charged $3.25 per lb ($7.15/kg) for exceeding the limit. To fly the long ranges needed for trans-Pacific service, the 314 carried 4,246 US gallons (16,070 l; 3,536 imp gal) of gasoline. The later 314A model carried a further 1,200 US gallons (4,500 l; 1,000 imp gal). A capacity of 300 US gallons (1,100 l; 250 imp gal) of oil was required for operation of the radial engines.
Pan Am's "Clippers" were built for "one-class" luxury air travel, a necessity given the long duration of transoceanic flights. The seats could be converted into 36 bunks for overnight accommodation; with a cruising speed of only 188 miles per hour (303 km/h) (typically flights at maximum gross weight were carried out at 155 miles per hour (249 km/h)) in 1940 Pan Am's schedule San Francisco to Honolulu was 19 hours. The 314s 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. The standard of luxury on Pan American's Boeing 314s has rarely been matched on 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.[7] Most of the flights were transpacific with a one-way ticket from San Francisco to Hong Kong, via the "stepping-stone" islands posted at $760 (or $1,368 round-trip).[8] The transatlantic flights continued to neutral Lisbon and Éire (Ireland) after war broke out in Europe in September 1939 (and until 1945) but military passengers and cargoes necessarily got priority and the service was more spartan.
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. For training, many of the transpacific flights carried a second crew.[9] 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 314 into port.[10]
Operational history[edit]
The first 314, Honolulu Clipper, entered regular service on the San Francisco-Hong Kong route in January 1939. A one-way trip on this route took over six days to complete. Commercial passenger service lasted less than three years, ending when the United States entered World War II in December 1941.
At the outbreak of the war in the Pacific, the Pacific Clipper was en route to New Zealand. Rather than risk flying back to Honolulu and being shot down by Japanese fighters, it was decided to fly west to New York. Starting on December 8, 1941 at Auckland, New Zealand, the Pacific Clipper covered over 31,500 miles (50,694 km) via such exotic locales as Surabaya, Karachi, Bahrain, Khartoum and Leopoldville. The Pacific Clipper landed at Pan American's LaGuardia Field seaplane base at 7:12 on the morning of January 6, 1942.
The Yankee Clipper flew across the Atlantic on a route from Southampton to Port
Washington, New York with intermediate stops at Foynes,
Ireland, Botwood,
Newfoundland, and Shediac,
New Brunswick. The inaugural trip occurred on June 24, 1939.
The Clipper fleet was pressed into military service during World War II, and the flying boats were used for ferrying personnel and equipment to the European andPacific fronts. The aircraft were purchased by the War and Navy Departments and leased back to Pan Am for a dollar, with the understanding that all would be operated by the Navy once four-engined replacements for the Army's four Clippers were in service. Only the markings on the aircraft changed: the Clippers continued to be flown by their experienced Pan Am civilian crews. American military cargo was carried via Natal, Brazil to Liberia, to supply the British forces atCairo and even the Russians, via Teheran. The Model 314 was then the only aircraft in the world that could make the 2,150-statute-mile (3,460 km) crossing over water,[11] and was given the military designation C-98. Since the Pan Am pilots and crews had extensive expertise in using flying boats for extreme long-distance over-water flights, the company's pilots and navigators continued to serve as flight crew. In 1943, President Franklin D. Roosevelt traveled to theCasablanca Conference in a Pan-Am crewed Boeing 314 Dixie Clipper.[2] Winston Churchill flew on the Bristol and Berwick,[2] adding to the Clippers’ fame during the war.[12]
After the war, several Clippers were returned to Pan American hands. However, even before hostilities had ended, the Clipper had become obsolete. The flying boat's advantage had been that it didn't require long concrete runways, but during the war a great many such runways were built for heavy bombers.[2] New long-range airliners such as the Lockheed Constellation and Douglas DC-4 were developed. The new landplanes were relatively easy to fly, and did not require the extensive pilot training programs mandated for seaplane operations. One of the 314's most experienced pilots said, "We were indeed glad to change to DC-4s, and I argued daily for eliminating all flying boats. The landplanes were much safer. No one in the operations department... had any idea of the hazards of flying boat operations. The main problem now was lack of the very high level of experience and competence required of seaplane pilots"[13]
Retirement[edit]
The last Pan Am 314 to be retired in 1946, the California Clipper NC18602, had accumulated more than a million flight miles.[14] Of the 12 Boeing 314 Clippers built three were lost to accidents, although only one of those resulted in fatalities: 24 passengers and crew aboard the Yankee ClipperNC18603 lost their lives in a landing accident at Lisbon, Portugal on February 22, 1943. Among that flight's passengers were prominent American author and war correspondent Benjamin Robertson who was killed and the American singer and film/TV actress Jane Froman who was seriously injured.[15]
Pan-Am's 314 was removed from scheduled service in 1946 and the seven serviceable B-314s were purchased by the start-up airline New World Airways. These sat at San Diego's Lindbergh Field for a long time before all were eventually sold for scrap in 1950. The last of the fleet, the Anzac Clipper NC18611(A), was resold and scrapped at Baltimore, Maryland in late 1951.
BOAC's 314As were withdrawn from the Baltimore-to-Bermuda route in January 1948, replaced by Lockheed Constellations flying from New York and Baltimore to Bermuda.[16]
Variants[edit]
- Model 314
- Initial production version with 1,500 horsepower (1,100 kW) Twin Cyclone engines, six built
- Model 314A
- Improved version with 1,600 horsepower (1,200 kW) Twin Cyclones with larger-diameter propellers, additional 1,200 US gallons (4,500 l; 1,000 imp gal) fuel capacity, and revised interior. Still air range approx 4,700 miles[17] six built
- B-314
- Five Model 314s impressed into military service with the U.S. Navy
- C-98
- Four Model 314s impressed into military service with the U.S. Army Air Forces
- Model 306
- A concept aircraft using a Model 314 fuselage with a tailless delta-wing planform. No examples built.
Operators[edit]