The Boeing 314 Clipper was an American long-range flying boat produced by Boeing from 1938 to 1941. One of the largest aircraft of its time, it had the range to cross the Atlantic and Pacific oceans. For its wing, Boeing re-used the design from the earlier XB-15 bomber prototype. Twelve Clippers were built, nine of which served with Pan Am. It was the first aircraft to carry a sitting American president, when in 1943 Franklin D. Roosevelt flew from Miami to the Casablanca Conference in Morocco, via Trinidad, Brazil, and The Gambia.[1][2]
As early as 1935 Pan American had identified that a truly trans-Pacific flying boat with unprecedented range and double the passenger payload of the airline's Martin M-130 would be required particularly if they were to provide a service across the longer more difficult Atlantic route and requested proposals from a number of American manufacturers.[3]
In February 1936, not long after the M-130s were introduced into service, Pan American launched a design competition for the first transoceanic airliner. Boeing, Douglas, Consolidated, Martin and Sikorsky were requested to provide preliminary studies and proposals for a long-range, four engine, marine aircraft. The new plane had to be able to transport up to 10,000 pounds of payload with a minimum range of 2,400 miles and cruise speed of 150 mph at an altitude of 10,000 feet.[4] Pan American was also adamant about providing comfort, space, and luxury for their passengers, as well as providing the ultimate in safety. Martin proposed a larger modified version of their M-130 called the M-156 which would offer a longer range and bigger payload with either a 53 day or 26 sleeper configuration.[3] Sikorsky proposed their S-45 whose six engines promised a 52,000 lb payload, but the first aircraft would not be available until late 1939 or early 1940 and it would cost more than the other proposals.[3]
Boeing’s submission
After receiving the Pan American request on 28 February 1936, Boeing decided to not submit a proposal as at the time the company's resources were committed on simultaneous contracts for the United States Army Air Corps.[5][6] The deadline had passed when a young Boeing engineer Wellwood E. Beall became aware of the Pan American project and thought that Boeing should consider submitting a bid.[6][7][8] Beall had had just returned to the United States in 1935 from serving as the company’s Far Eastern manager with responsibility for selling the company's fighter and transport planes to the Chinese Government.[9] During his time in China he had often thought about the design of a large flying boat and he now worked in his spare time on a preliminary design.[6] As Pan American had specified the engines and propellers in advance, Beall proposed to use the wing of the cancelled XB-15 bomber, which had already been designed and wind-tunnel tested; this would allow Boeing to confine the design effort to the hull and the flotation stability and tail assemblies.[8][6] To supplement his preliminary design study, his then wife, well-known artist and muralist Jean Cory Beall, produced colour paintings of the cabin interiors. His proposal was accepted by Boeing management and he was given permission to request an extension from Pan American, which was granted.[6][10][11]
Beall was transferred to the engineering department and allocated 11 engineers to work on the project.[4][6] The engineering team calculated that the optimum wingspan for the flying boat needed to 152ft (46m) compared with the XB-15’s 149ft (45m). The shortfall was overcome by adding 36in (914mm) to the width of the fuselage.[12] He combined the wing with more powerful Wright R-2600 Twin Cyclone engines, each of which produced 50% more power than the 850hp (630kW) of the XB-15’s Pratt & Whitney R-1830 Twin Wasp engines.[13] The XB-15’s engine nacelles were also retained as they had originally been designed to house 2,600hp (1,900kW)Allison V-3420liquid-cooledW engines, which since these were not ready, had been replaced on the bomber by the smaller and less powerful Pratt & Whitneys.[6] The engineers estimated that their proposed design would weigh 40,000 lbs and could carry a payload of up to 42,500 lbs.[3] Sufficient work was completed by May 1936 for Beall, company president Claire Egtvedt, aerodynamicist Ralph LaVenture Cram (1906-1939) to depart on 9 May 1936 from Seattle to New York where they made a presentation of their proposal to Pan American.[6]
Pan American accepted Boeing’s proposal, awarding it a $4.8 million contract on 21 July 1936 for six aircraft with an option for six more.[6][4] This order represented the first that Pan American had placed with the company. The first aircraft was to be delivered by 21 December 1937.[3] An amendment to the contract on 20 January 1937 granted a three month extension to the specified delivery date for the first six aircraft.[6]
The aircraft's introduction was impacted by the complexity of the design and testing and the passage of the Civil Aeronautics Act in 1938, establishing the Civil Aeronautics Board, which had the power to review and certify new aircraft. Boeing missed its contracted delivery date by 13 months.
Testing
Boeing Model 314 NX18601 flying over Elliot Bay
There was no dedicated prototype; instead, the first production unit, NX-18601, was used for testing. Once completed it was launched into the Duwamish Waterway and towed to Elliott Bay on Puget Sound for taxi and flight tests.[4] Its wingspan was so great that it had to be turned diagonally to pass through the supports of bridges spanning the waterway.[14] From here it commenced its first taxiing run on 3 June with test pilot Edmund T. Allen at the controls, but he soon identified that it was too lightly loaded when a gust of wind lifted one wing and dipped the other and after increasing the engine power failed to correct the situation it became necessary for all spare crew members to climb out onto the raised wing to balance the aircraft and allow it to safely return to shore.[15] Following the installation of temporary ballast further taxiing tests continued for a week.[4]
The first test flight was undertaken by Allen on the 7 June 1938 and once airborne it was immediately identified that the aircraft had insufficient rudder control.[15][16] He was only able to turn the aircraft by increasing the power of the engines on one wing and decreasing that of the engines on the other. This first flight lasted 38 minutes.[14] This directional instability had been observed during wind tunnel tests but Boeing management had rejected any changes to the original single fin configuration to correct it.[6] Someone else who had identified the issue was George S. Schairer, at the time a young engineer at Consolidated Aircraft. After seeing a photograph of NX-18601 with its original tail configuration on the cover of an aviation magazine he had written to Boeing, stating that he believed the tail was too small.[17] NX-18601 was immediately modified into a twin fin configuration, but this was still found to be insufficient and so the centerline vertical fin was restored, which resolved the issue and this three fin arrangement became the production configuration.[15][18]
Months of extensive testing continued and on 26 January 1939, the 314 was approved the Civil Aeronautics Board for commercial airworthiness.[19]
Design
The 314 was a high wing flying boat which used a series of heavy metal ribs and spars to create a robust fuselage and cantilevered wing, eliminating the need for external drag-inducing struts to brace the wings. It was metal skinned with the exception of the control surfaces.
The aircraft were assembled at Boeing's Plant 1 on the Duwamish River in Seattle. The design required the production of 6,000 engineering drawings, 50,000 separate parts, 11 miles of electrical wiring, 576,000 rivets[20] and 15,200 bolts.[15]
Engines
The original six 314s were powered by four air-cooled, supercharged Wright Aeronautical Corporation Cyclone 14 GR2600A2, two-row, 14-cylinder radial engines.[6][21] The six 314A’s had the more powerful Cyclone 14 GR2600A2A engines.[21] These engines were subsequently retrofitted to the original 314s during engine overhauls.
Commonly known as “Twin Cyclones”) these engines were the first to use 100 octane gasoline in commercial service.[6] The 314 was the first use of this engine, which at the time was not only the largest engine installed on a commercial aircraft, but also offered the lowest specific fuel consumption.[6]
The engines drove Hamilton Standard hydromatic full-feathering constant-speed propellers through reduction gears.[23] The development of these propellers had been fostered by Pan American. In a first for commercial operation these offered both variable pitch and full-feathering which meant that in the event of an engine fault the three blades of the 14 feet (4.3m) diameter propellers could be turned directly into the airflow and so would not rotate and risk further damaging the engine by “windmilling”.[6] Turning the blades into the airflow also reduced drag which was important on long flights over water.[6] On the GR2600A2 engines the propellers had a diameter of 14 feet (4.3m), while on the GR2600A2A, they had a diameter of 14feet 10inches (4.52m)[24] and when installed in 1940 they featured the first NACA propeller aerofoil sections on a commercial aircraft.[25] The 314 featured the first use of rate of flow fuel meters when they were installed in 1939 at the engineer’s station as a permanent fitting on an aircraft. Previously they had been only installed as a temporary device during testing. Pan American had supported their development.
Fuel capacity
To fly the long ranges needed for trans-Pacific service, the 314 carried 4,246 US gallons (16,070L; 3,536impgal) of gasoline. The later 314A model carried a further 1,200 US gallons (4,500L; 1,000impgal). A capacity of 300 US gallons (1,100L; 250impgal) of oil was required for operation of the radial engines.
Wings
The wings were constructed in five sections of an aluminum outer skin formed over spars constructed out of bolted square aluminum alloy tube trusses while the ribs were formed out of aluminum alloy tubes and channels. They had a NACA 0018 airfoil profile at their root which changed to a NACA 0010 profile at their tip.[26] The outer ends of the wings were made watertight, which allowed them to provide flotation if the aircraft heeled over in rough conditions.[6]
The wings were thick enough to incorporate a crawlspace, through which each engine nacelle could be accessed by a flight engineer. After removing the two sections of the stainless-steel firewall behind each engine, they could service and if possible repair it in flight, as the fully-feathering propellers made it possible for an engine to be completely shut down. Between June 1939 and June 1941, 431 in-flight engine repairs were performed.[7] The most common problem was fouled spark plugs. Each nacelle had a side access door on either side which opened downwards and which could be used as work platforms.[6] Each aircraft also carried portable work platforms that could be hung on the outside, forward of the access doors to allow work on the engines.[6] The centre sections of each wing contained two fuel tanks as well as compartments for transport of cargo, in particular mail.[6]
The wings were fitted with metal-framed fabric-covered "split" type flaps located under each wings trailing edge. When taking off the flaps were set to 20 degrees and when landing their full deflection of 60 degrees was typically used.[6] The metal-framed fabric-covered ailerons were of the Frieze type, each having a single trim tab divided into two separate units to reduce any binding of the aileron’s hinge when the wing flexed under load.
Hull
The 12feet 6inches (3.81m) wide hull was of all metal construction and differed from previous flying boats in that the lower central section was constructed as an integral section with the wings and inner engine nacelles.[6] The remaining parts of the hull were separately constructed in sections and then attached to it. Instead of the hull being split into numerous watertight compartments the hull had only two full height watertight bulkheads, a front collision bulkhead ahead of the flight deck and a compartmented double bottom.[6]
The 314 had a transverse hydroplane step just to the rear of the centre of gravity with a second step, farther aft which terminated on the original 314’s at a rudder for steering the flying boat when it was in the water.[6] This rudder was subsequently removed and was not fitted to the 314As as it was found in service that the aircraft could be steered in the water by varying the power to the engines on each side.
The lower mid hull of the 314 was fitted with Dornier-style sponsons.[27] These 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 on the water, they acted as a platform for boarding and exiting, and they possessed an intentional air foil shape which contributed additional aerodynamic lift in flight. Each was divided into five compartments, two of which were used as fuel tanks. Each sponson had sufficient reserve buoyancy to maintain stability if once of the compartment filled with water.[6] The fuselage drew 4 feet (1.2m) of water.[6]
The tail section consisted of a metal-skinned horizontal stabilizer on those centre was a single central metal-frame fabric covered fin and on each outboard end, a metal-skinned outboard fully cantilevered fin. The metal skinned stabilizer was built as a single unit and was bolted directly to the top of the hull with a streamline fairing for it. The metal-frame fabric-covered elevators fitted to on each end of the stabilizer were so large and heavy that in a first they were fitted with separate control and trim tabs on each side. The control tab had twice the effectiveness of the trim tab. Springs, which gave a degree of "feel" proportional to elevator movement were incorporated in the connections to the pilot’s controls moved the tabs, which in turn moved the elevators. At high angles of movement the spring became rigid and further elevator movement was directly from the control column. While not aerodynamically balanced the elevators were statically balanced to 85% by a counterweight in the hull and by smaller weights on their outboard ends.[6] The metal-frame fabric covered rudders used the same spring-controlled tab system as the elevators and incorporated a small degree of aerodynamic balance.
Interior
At the front was a bow compartment containing a 91 pounds (41kg) pound anchor and 150 feet (46m) of rope for tie off the aircraft. Access was via a hatch on each side of the nose, while a smaller top hatch allowed a crewman to attach either a towing line, mooring line or anchor line to two removable vertical mooring posts.[6] From this compartment a gangway led up to the cockpit on the upper deck.[28] At the rear of the compartment there were four tube and canvas bunks for the crew that folded up into the walls of the collision bulkhead.[6]
Behind it were two decks, an upper and a lower deck.
Upper deck
On the upper deck was the flight deck, cargo hold, crew quarters, a toilet and baggage compartments. On the roof of the flight deck was two pitot tubes and a retractable spotlight. The large flight deck was 21feet 4inches (6.50m) long and 9feet 6inches (2.90m) wide with full headroom throughout. At the front was the cockpit. The captain sat in the left and the co-pilot to the right. Between the pilots was a hatch leading down into the bow compartment. Behind the cockpit (which could be closed off by heavy curtains at night to prevent light from the rest of the flight deck reducing the pilot’s night vision) was the flight operations room. On the left-hand side of the flight operations room was the navigator's 7 feet (2.1m) long chart table, followed by a small table and chair for the watch officer. On the right) side was a circular staircase that led down to the lower deck. Behind this was the radio operator's station, followed by the flight engineer’s station.
On either side of the flight operations room were oval hatches that led to the crawlspaces in the respective wings. On the rear bulkhead was the door to the cargo hold which was located in the centre of the wing over the centre of gravity. The heaviest cargo was stored here with space left for the crew to pass through. Outside access to the cargo compartment was via a hatch in the top of the wing, the hatch also incorporating a celestial observation dome.[6] The navigator used this dome to make sightings on the stars with his sextant. The dome’s location at the 314’s centre of gravity assisted in making these sightings as steady as possible, while the red light in this compartment allowed reading of the sextant without impacting on the navigator’s night vision. If clouds prevented a reading then a straight course could be maintained by employing dead reckoning. To compensate for wind blowing the aircraft sideways the drift could be estimated by dropping a flare into the water through a small hatch in each wing root. By carefully watching the flare to see if it stayed in line with the tail of the aircraft or moved to one side or the other, the navigator could estimate the drift.
Behind the cargo compartment was the crew quarters where the crew had the use of three tube and canvas bunks on which to sleep.[6] Behind the upper deck’s crew quarters was an area for storage of the passenger’s luggage.
The lower deck was divided into 11 sections: five standard passenger compartments, a deluxe compartment, a dining lounge, gallery, ladies restroom and men's room. The aft compartments had a step between each as their floor level rose due to the curvature of the bottom of the aircraft.
Each standard compartment could seat ten or sleep six, with four sleeping on the right (starboard) side in two upper and lower berths, while on the left (port) side there was a single upper and lower, each fitted with a privacy curtain. It took a steward 30 minutes to convert each compartment into its sleeping configuration.[28] The deluxe compartment which was also known as the “bridal suite” was located at the extreme rear of the deck and contained a three-cushion davenport that could be converted into upper and lower sleeping berths. Also there was a love seat, a coffee table, a small leather covered dressing and writing table, a beige stool, a mirror, a wardrobe and a concealed wash basin.[29]
The ladies restroom contained a mirror, a sink with hot and cold running water, towels, tissues, two leather upholstered swivel stools and, behind a door, a separate toilet.[29] The men's room had an outlet for an electric razor, while its attached toilet room had both a toilet and a urinal. Water for flushing of the toilets was from an overhead tank, with all waste flushed overboard.[29]
The dining lounge had seating for 11 passengers during daytime with small pullout tables on which to accommodate their drinks and snacks. In the evening the furniture converted into a formal dining configuration which could seat 14 passengers at five tables, with meals served with linen tablecloths, crystal glasses, and full waiter service.[29] Two drinking fountains were provided on each aircraft.
The 4 feet (1.2m) square gallery had a linoleum covered floor, a 12-inch (300 mm) by 10-inch (250 mm) aluminum sink, a drip coffee maker, an aluminum icebox, a combination stove and steamer, a cabinet containing a two-tiered dish rack capable of accommodating 200 fine China plates, two glass and cup racks, a saucer rack, eight drawers and a waste bin.[30] A separate cabinet held 350 Gorham sterling-silver “Moderen” pattern cutlery, a silver-plated tea set and ten pairs of sterling salt and pepper shakers.[30] There were approximately 1,000 serving items, which weighed a total of 235 pounds (107kg), with typically 256 pounds (116kg) of food carried.[30] Valuables and passenger passports were housed in one of three lockable cabinets.
Norman Bel Geddes who had designed the interior of Pan American’s Martin M-130 was employed to design the interior of the 314.[29] Wherever possible efforts were made to reduce weight. Duralumin was used in the furniture frames and plastic in the portholes rather than glass. Lightweight carpet was used to assist in noise damping. The cushions were made of latex mixed with horsehair from Australia. Howard Ketcham, a colour expert from New York assisted in the selection of colours that would complement Bel Geddes’ design and also reflect light, yet control brightness and create the impression of openness to reduce any feelings of claustrophobia.[29] This resulted in the use of colours called Miami Sand Beige, Pan American Blue and Skyline Green. Window blinds were of accordion pleated roller design and manufactured by Claude D. Carver Company of New York that used a washable material called “Tontine”.[29]
Auxiliary equipment
The aircraft’s electrical system was of the direct current type, powered by two 15 volt generators supported by two 12 volt batteries to provide both 12 volts and 24 volts. The 314 had an extensive suite of radio equipment, which was housed in three different locations. Normally powered by the main electrical system it could in the event of a loss of this supply be powered from a self-contained emergency generator. The radio equipment as well as other specialised equipment was provided by Pan American, with their staff at the Boeing’s factory assisting in its installation and commissioning. The aircraft was fitted with a heating and cooling system that could deliver 360,000 BTUs per hour from manifolds around engine exhausts and 170,000 cubic feet of air per hour. The aircraft was fitted with a system that could detect any leakage of carbon dioxide from the engines into the interior of the aircraft.
Safety features
The aircraft had 15 different methods of exiting the aircraft in an emergency, with each passenger compartment having two. With the exception of the fuel tank hatches, all hatches on the aircraft could be opened without threatening the structural integratory of the aircraft. Emergency equipment was stored in the nose compartment including at least two weeks of canned food for all the passengers, stored water, life rafts, and fishing and hunting tackle. Each passenger seat had a lifejacket, with the aircraft equipped with axes, flares, ring-type life preservers and rope. There were also eight 10-person life rafts, four of which could be accessed from outside of the aircraft. To reduce the risk of fire Boeing made efforts wherever possible to use fireproof materials in the cabins, most notably in the insulation, upholstery and wall linings.
Service levels
Pan American's "Clippers" were built for "one-class" luxury air travel, a necessity given the long duration of transoceanic flights. In 1940, Pan American's scheduled time from San Francisco to Honolulu was 19 hours, with a cruising speed of 188 miles per hour (303km/h), although flights at maximum gross weight were typically flown at 155 miles per hour (249km/h). Clipper service catered to elite businessmen and the wealthy traveler. 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 seats could be converted into 36 bunks for overnight accommodation. The standard of luxury on Pan American's Boeing 314s has rarely been matched on heavier-than-air transport since then. A round trip from New York to Southampton was $675 (equivalent to $15,000in 2023),[31] while a one-way ticket from San Francisco to Hong Kong via the "stepping-stone" islands cost $760 (equivalent to $16,000in 2023).[32] The Pan American Boeing 314 Clippers brought exotic destinations like the Far East within reach of air travelers and came to represent the romance of flight. Most of the flights were transpacific, while transatlantic flights to neutral Lisbon and Ireland continued 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.
Crew
Equally critical to the 314's success was the proficiency of its Pan American 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.[33] Only the very best and most experienced flight crews were assigned Boeing 314 flying boat duty. Before coming aboard, all Pan American 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, celestial 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.[34]
The 314 normally had a crew of 10[35] but to address crew fatigue on long ocean flights the aircraft this could increase up to 16, divided into two shifts with a shift consisting of a pilot, co-pilot, navigator, radio operator, flight engineer, watch officer (also known as the "Master") and two cabin attendants.[6]
Maintenance
Major maintenance and repairs were undertaken by manoeuvring the flying boat onto a 20 ton beaching cradle and pulling it up a ramp onto land and into a hangar. When overhauls were required, two three-story high 15-ton working platforms were wheeled into position, one for each wing, to allow access to all parts of the aircraft.[36] Taking a year to design they each cost $10,000 and provided 2,000 square feet (190m2) of working area equipped with work benches, telephones, compressed air, electricity supplies, floodlights, spare parts and on the lowest level, offices for the foreman and inspectors. At the end of the overhaul the aircraft would be subjected to a four hour test flight.[36] A 314 would typically spend two days between flights on an overhaul, which involved washing the aircraft, inspection, maintenance and repair.[36] Replacement of an engine took four hours. A replacement sponson cost $24,000.[36]
Pan American’s major maintenance facilities were located at La Guardia, New York and on Treasure Island in San Francisco Bay, California.
Operational history
Boeing 314 in US Navy colors, c. 1942Boeing 314 Clipper in Shediac Bay, c. 1941Flown "triptych" cover carried around the world on PAA Boeing 314 Clippers and Imperial Airways Short S23 flying boats June 24 – July 28, 1939
Entry into service
The first aircraft to be delivered was NC18602 which was flown on 27 January 1939 by Boeing test pilot Earl Ferguson and Wellwood Bell as co-pilot from Lake Washington to Astoria in Oregon.[19] It was delivered to Pan American in Oregon in order to avoid a Washington state tax, which had been introduced during the Depression to increase state revenues.[19] It was accepted by Captains Harold E. Gray and Charles Vaughn and flown by them to Pan American’s base at San Francisco. The remaining five aircraft were delivered at approximately monthly intervals, the last on 16 June 1939.[19] NC18501 and NC18602 were assigned to the Pacific and the others four to the Atlantic.[19] As with all new designs there were a number of issues which required modifications to the aircraft. As a result it wasn’t until the end of July 1939 before the 314s were able to offer a full service on the Pacific routes.[19]
The first 314 flight on the San Francisco-Hong Kong route left Alameda on February 23, 1939 with regular passenger and Foreign Air Mail Route #14 service beginning on March 29.[37][38][39] 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. Passengers and their baggage were weighed, with each passenger allowed up to 77 pounds (35kg) free baggage allowance (in the later 314 series) but then charged $3.25 per pound ($7.2/kg) (equivalent to $70in 2023) for exceeding the limit.[40]
Pan American had an option to purchase further 314s. Confident that the problems that had occurred with the first order had been resolved and having found the 314 to be more reliable in service than the Martin M-130 they exercised this option, ordering six. The order was placed two days before its expiry date of 1 October 1939.[41] Planned delivery was in 1941, with the goal of doubling the service on both Atlantic and Pacific routes by retiring its remaining two Martin 130s and allocating six of the 314s to the Pacific and the other six to the Atlantic.[41]
However, the fall of France in 1940 caused some doubt about whether the Atlantic service could continue; passenger numbers were already reduced by the war, and if Spain or Portugal were to join the Axis, then the flights to Lisbon would be forced to stop. Pan American began to consider reducing its order and, in August 1940, reached an agreement to sell two of the six under construction to the United Kingdom for $1,035,400 each with an option to purchase a third if Pan American stopped its Lisbon service.[42] This option for a third aircraft was soon exercised. The purchase of the three aircraft included 12 spare GR2600A2A engines at a cost of $16,753 each and $21,750 for 19 Hamilton propellers.[42] The aircraft were to be operated by the British Overseas Airways Corporation (BOAC) and were primarily intended for the UK – West Africa route, as existing flying boats could not travel this route without stopping in Lisbon. The sale made a small net profit for Pan American – priced at cost plus 5% – and provided a vital communications link for Britain, but was politically controversial. In order to arrange the sale, the junior minister Harold Balfour had to agree to the contract with no government approval, leading to stern disapproval from Winston Churchill and lengthy debate by the Cabinet over the propriety of the purchase.[43]
Pan American provided training for BOAC staff and delivered the aircraft to La Guardia in New York, where 33 days were spent changing their registration and painting them in a new colour scheme.[42]
Churchill later flew on the Bristol and Berwick in January 1942 from Washington, D.C. to England,[44] and he praised the plane intensely,[43] adding to the Clippers' fame during the war.[45]
At the outbreak of the war in the Pacific in December 1941, the Pacific Clipper was en route to New Zealand from San Francisco. Rather than risk flying back to Honolulu and being shot down by Japanese fighters, it was directed to fly west to New York. Starting on December 8, 1941 at Auckland, New Zealand, the Pacific Clipper covered over 31,500mi (50,700km) via locations including 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.[46]
Wartime service
Pan American's Clipper fleet was pressed into US military service during World War II, and the flying boats were used for ferrying personnel and equipment to the European and Pacific fronts. The aircraft were purchased by the War and Navy Departments and leased back to Pan American 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 American civilian crews. American military cargo was carried via Natal, Brazil to Liberia, to supply the British forces at Cairo and even the Russians, via the Persian Corridor. The Model 314 was then the only aircraft in the world that could make the 2,150-statute-mile (3,460km) crossing over water.[47] The Army gave the aircraft the designation C-98, but the Navy—which used a different designation system at the time—disregarded this designation and operated the aircraft under the company designation B-314.[48] In February 1942, forty women were hired by Pan American to replace male mechanics in the hangars at LaGuardia to perform service, repair and overhaul of the Clippers for the European service.[49] Maintenance demands were such that it took "141 mechanics, working three 8-hour shifts, to perform in two days the complete inspection of servicing routine which must be carried out before a Clipper just in from Europe can be sent on the return trip."[50] Since the Pan American 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 the Casablanca Conference in a Pan-Am crewed Boeing 314 Dixie Clipper.[44]
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 did not require long concrete runways, but during the war many such runways had been built for heavy bombers.[44] New long-range airliners such as the Lockheed Constellation and Douglas DC-4 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."[51]
Retirement
BOAC Clipper Berwick taxiing on Lagos Lagoon, Lagos, Nigeria.
The last Pan American 314 to be retired, the California Clipper NC18602, in 1946, had accumulated more than a million flight miles.[52] 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 Clipper NC18603 lost their lives in a landing accident at Cabo Ruivo Seaplane Base, in Lisbon, Portugal on February 22, 1943.[53] Among that flight's passengers were prominent American author and war correspondent Benjamin Robertson, who was killed, and the American singer and actress Jane Froman, who was seriously injured.[54]
Pan-Am's 314 was removed from scheduled service in 1946 and the seven serviceable 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.[55]
Variants
Model 314
Initial production version with GR2600A2 Twin Cyclone engines, six built for Pan American at an average of $668,908 at a time when a DC-3 cost $115,000.[56] In addition, Pan American purchased $756,450 of spares.[56]
Model 314A
This improved version featured:
An increased gross take-off weight of 84,000 pounds (38,000kg), an increase of 2,000 pounds (910kg). Following reinforcement of their airframes the earlier 314s were also cleared to have this higher take-off weight.[41]
An improved engines, the GR2600A2A which gave more power and which drove larger diameter propellers with a improved blade design.
The step on the bottom of the hull was moved further back to prevent the porpoising that had troubled the 314.
An increase in fuel capacity from 4,200 gallons to 5,448 gallons. This offered improved security on more turbulent winter flights. This improvement was retro fitted to the original 314s.[41][57]
The oil capacity was decreased from 206 to 300 gallons due to the use of more efficient hopper oil tanks, which as well as reducing the oil load, improved cold weather engine starting.[41]
A revised interior.
The 314A dispensed with the recessed steps that led up the side of the nose.[6]
Successfully landed 650 miles east of Oahu after losing power in two engines while flying for the US Navy on November 3, 1945. Aircraft mechanics from the escort carrierManila Bay were unable to repair the engines at sea. The seaplane tenderSan Pablo attempted towing into port; but the flying boat was damaged in a collision with the tender and deliberately sunk on November 14 by Oerlikon 20 mm gunfire after salvage was deemed impractical.[18]
Started transatlantic mail service. Crashed on February 22, 1943, when a wing hit the water during a turn on landing at Lisbon, Portugal. A total of 24 of 39 on board were killed.[58]
NC18604
314
Atlantic Clipper
1939–1946
Purchased by the US Navy in 1942, but operated by Pan Am; salvaged for parts.
NC18605
314
Dixie Clipper
1939–1950
Started transatlantic passenger service, later sold to World Airways. First presidential flight, when she flew Franklin D. Roosevelt to the Casablanca Conference in January 1943. Scrapped 1950.
Temporarily named California Clipper to replace 18602 that was being moved to Atlantic service, renamed Pacific Clipper in 1942. Later sold to Universal Airlines. Damaged by storm and salvaged for parts.
NC18611
314A
Anzac Clipper
1941–1951
Sold to Universal Airlines 1946, American International Airways 1947, World Airways 1948. Sold privately 1951, destroyed at Baltimore, Maryland 1951.
NC18612
314A
Cape Town Clipper
1941–1946
Sold to US Navy 1942, American International Airways 1947. As the Bermuda Sky Queen she ran out of fuel while crossing the Atlantic on a westward flight, and ditched at sea about 500 miles east of Gander on October 14, 1947. After the rescue of all passengers and crew, she was sunk by the United States Coast Guard as a hazard to navigation.[59]
Aircraft operated by BOAC
Registration
Type
Name
In service
Remarks
G-AGBZ
314A (#2081)
Bristol
1941–1948
Originally NC18607, sold to General Phoenix Corporation, Baltimore as NC18607 in 1948
G-AGCA
314A (#2082)
Berwick
1941–1948
Originally NC18608, sold to General Phoenix Corporation, Baltimore as NC18608 in 1948. This aircraft flew both Winston Churchill and Lord Beaverbrook, Britain's Minister of Supply back urgently to the United Kingdom in mid-January 1942 after the British Prime Minister's extended stay in the United States following the attack on Pearl Harbor. Churchill was the first head of government to make a transatlantic crossing by plane.[60][61][62]
G-AGCB
314A (#2084)
Bangor
1941–1948
Originally NC18610, sold to General Phoenix Corporation, Baltimore as NC18610 in 1948
Surviving aircraft
Full-size replica of a Boeing 314 at the Foynes Flying Boat Museum, County Limerick, Ireland
None of the dozen 314s built between 1939 and 1941 survived beyond 1951, with all 12 being cannibalized for parts, scuttled, scrapped, or otherwise written off. Underwater Admiralty Sciences, a non-profit oceanographic exploration and science research organization based in Kirkland, Washington, announced in 2005, at the 70th Anniversary of the first China Clipper flight in San Francisco, its plans to survey, photograph, and possibly recover the remains of the hulls of two sunken 314s: NC18601 (Honolulu Clipper), scuttled in the Pacific Ocean in 1945; and NC18612 (Bermuda Sky Queen, formerly Cape Town Clipper), sunk in the Atlantic by the Coast Guard in 1947. UAS has also spent significant time at Pan American reunions and with individual crewmembers and employees of Pan American conducting videotaped interviews for the mission's companion documentary.[63][64] However, as of 2014, no search or recovery had been attempted, with the most recent news from 2011 suggesting that the company was still in need of at least US$8 million to get the plan under way.[65]
There is a life-size 314 mockup at the Foynes Flying Boat Museum, Foynes, County Limerick, Ireland, located on the site of the original transatlantic flying-boat terminus.[66]
Specifications (314A Clipper)
Data from Jane's Fighting Aircraft of World War II[67]
Propellers: 3-bladed Hamilton Standard fully-feathering constant-speed propellers
Performance
Maximum speed: 210mph (340km/h, 180kn) at 6,200ft (1,890m)
Cruise speed: 188mph (303km/h, 163kn) at 66.5% power at 11,000ft (3,353m)
Range: 3,685mi (5,930km, 3,202nmi) normal
Cultural influence
Inspired by the airplane, Smith Corona designed, manufactured, and marketed a typewriter model they called the Clipper from 1945–1960. The typewriter model's logo prominently featured the Boeing 314 Clipper on the typewriter's body which served as a reminder of the luxury and design of the original airplane.[68]
Pan American World Airways, originally founded as Pan American Airways and more commonly known as Pan Am, was an airline that was the principal and largest international air carrier and unofficial overseas flag carrier of the United States for much of the 20th century. It was the first airline to fly worldwide and pioneered numerous innovations of the modern airline industry, such as jumbo jets and computerized reservation systems. Until its dissolution on December 4, 1991, Pan Am "epitomized the luxury and glamour of intercontinental travel", and it remains a cultural icon of the 20th century, identified by its blue globe logo, the use of the word "Clipper" in its aircraft names and call signs, and the white uniform caps of its pilots.
China Clipper (NC14716) was the first of three Martin M-130 four-engine flying boats built for Pan American Airways and was used to inaugurate the first commercial transpacific airmail service from San Francisco to Manila on November 22, 1935. Built at a cost of $417,000 by the Glenn L. Martin Company in Baltimore, Maryland, it was delivered to Pan Am on October 9, 1935. It was one of the largest airplanes of its time.
A flight engineer (FE), also sometimes called an air engineer, is the member of an aircraft's flight crew who monitors and operates its complex aircraft systems. In the early era of aviation, the position was sometimes referred to as the "air mechanic". Flight engineers can still be found on some larger fixed-wing airplanes and helicopters. A similar crew position exists on some spacecraft. In most modern aircraft, their complex systems are both monitored and adjusted by electronic microprocessors and computers, resulting in the elimination of the flight engineer's position.
The Boeing 377 Stratocruiser was a large long-range airliner developed from the C-97 Stratofreighter military transport, itself a derivative of the B-29 Superfortress. The Stratocruiser's first flight was on July 8, 1947. Its design was advanced for its day; its relatively innovative features included two passenger decks and a pressurized cabin. 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 Short Empire was a medium-range four-engined monoplane flying boat, designed and developed by Short Brothers during the 1930s to meet the requirements of the growing commercial airline sector, with a particular emphasis upon its usefulness upon the core routes that served the United Kingdom. It was developed and manufactured in parallel with the Short Sunderland maritime patrol bomber, which went on to serve in the Second World War; a further derivative that was later developed was the piggy-back Short Mayo Composite.
Edwin Charles Musick was chief pilot for Pan American World Airways and pioneered many of Pan Am's transoceanic routes including the famous route across the Pacific Ocean, ultimately reaching the Philippine Islands, on the China Clipper.
The Sikorsky S-42 was a commercial flying boat designed and built by Sikorsky Aircraft to meet requirements for a long-range flying boat laid out by Pan American World Airways in 1931. The innovative design included wing flaps, variable-pitch propellers, and a tail-carrying full-length hull. The prototype first flew on 29 March 1934, and, in the period of development and test flying that followed, quickly established ten world records for payload-to-height. The "Flying Clipper" and the "Pan Am Clipper" were other names for the S-42.
The Pacific Clipper was an American Boeing 314 Clipper flying boat, famous for having completed an unplanned nearly around-the-world flight in December 1941 and January 1942 as the California Clipper. Aviation experts called the flight the first commercial circumnavigation of the globe because the aircraft made it back to its country of origin.
The Sikorsky S-40 was an American amphibious flying boat built by Sikorsky in the early 1930s for Pan American Airways. During WW2 they were used by the United States Navy for training.
The Boeing Model 307 Stratoliner is an American stressed-skin four-engine low-wing tailwheel monoplane airliner derived from the B-17 Flying Fortress bomber, which entered commercial service in July 1940. It was the first airliner in revenue service with a pressurized cabin, which with supercharged engines, allowed it to cruise above the weather. As such it represented a major advance over contemporaries, with a cruising speed of 220 mph (350 km/h) at 20,000 ft (6,100 m) compared to the Douglas DC-3's 160 mph (260 km/h), at 8,000 ft (2,400 m) then in service. When it entered commercial service it had a crew of five to six, including two pilots, a flight engineer, two flight attendants and an optional navigator, and had a capacity for 33 passengers, which later modifications increased, first to 38, and eventually to 60.
The Martin 156, referred to in the press variously as the "Russian Clipper", "Moscow Clipper", or "Soviet Clipper" was a very large flying boat aircraft intended for trans-Pacific service. The single example of the M-156 was designed and built in response to a request from Pan American World Airways to provide a longer-range replacement for the Martin M-130.
The Short Solent is a passenger flying boat that was produced by Short Brothers in the late 1940s. It was developed from the Short Seaford, itself a development of the Short Sunderland military flying boat design.
The Sikorsky VS-44 was a large four-engined flying boat built in the United States in the early 1940s by Sikorsky Aircraft. Based on the XPBS-1 patrol bomber, the VS-44 was designed primarily for the transatlantic passenger market, with a capacity of 40+ passengers. Three units were produced: Excalibur, Excambian, and Exeter, plus two XPBS-1 prototypes.
The Consolidated Commodore was an American flying boat built by Consolidated Aircraft and used for passenger travel in the 1930s, mostly in the Caribbean, operated by companies like Pan American Airways.
The Martin M-130 was a commercial flying boat designed and built in 1935 by the Glenn L. Martin Company in Baltimore, Maryland, for Pan American Airways. Three were built: the China Clipper, the Philippine Clipper and the Hawaii Clipper. All three had crashed by 1945. A similar flying boat design called the Martin 156 and named Russian Clipper, was built for the Soviet Union; it had a larger wing and twin vertical stabilizers.
The Latécoère 521 was a French six-engined double deck flying boat designed and manufactured by Pierre-Georges Latécoère. At the time of its completion, it held the distinction of being the largest aircraft to be built in France as well as one of the first large passenger aircraft capable of flying trans-Atlantic routes.
Pan Am Flight 1104, trip no. 62100, was a Martin M-130 flying boat nicknamed the Philippine Clipper that crashed on the morning of January 21, 1943, in Northern California. The aircraft was operated by Pan American Airways, and was carrying ten US Navy personnel from Pearl Harbor, Hawaii, to San Francisco, California. The aircraft crashed in poor weather into mountainous terrain about 7 mi (11 km) southwest of Ukiah, California.
Pan Am Flight 526A, a Douglas DC-4, took off from San Juan-Isla Grande Airport, Puerto Rico, at 12:11 PM AST on April 11, 1952 on a flight to Idlewild International Airport, New York City with 64 passengers and five crew members on board. Due to inadequate maintenance, engine no. 3 failed after takeoff, followed shortly by engine no. 4. Nine minutes after takeoff, the aircraft ditched in rough seas 11.3 miles NW of San Juan Airport, broke apart and sank after three minutes. Panicking passengers refused to leave the sinking wreck. 52 passengers were killed, and 17 passengers and crew members were rescued by the USCG. After this accident it was recommended to implement pre-flight safety demonstrations for over-water flights.
The China Clipper flight departure site is listed as California Historical Landmark number 968. It is the site from which Pan American World Airways initiated trans-Pacific airmail service on November 22, 1935. A flying boat named China Clipper made the first trip, and the publicity for that flight caused all flying boats on that air route to become popularly known as China Clippers. For a few years, this pioneering mail service captured the public imagination like the earlier Pony Express, and offered fast luxury travel like the later Concorde.
Honolulu Clipper was the prototype Boeing 314 flying boat designed for Pan American Airways. It entered service in 1939 flying trans-Pacific routes.
↑ Swanborough, Gordon; Bowers, Peter M. (1976). United States Navy Aircraft since 1911 (2nded.). Annapolis, Maryland: Naval Institute Press. p.416. ISBN0-87021-968-5.
↑ Wolfert, Ira (February 8, 1942). "Feminine 'Grease Monkeys' Girls Tune Up Giant Planes". The Miami News. p.1.
↑ "[Airport] Building Equipment: Heating, Lighting, Power, Service Outlets." (New) Pencil Points, February 1943, 61.
↑ Brock 1978, p.224 Brock also reports cheap postwar availability to Pan American of DC-4s and "Connies" was an important factor.
↑ Roberts, Andrew (2018). Churchill: Walking with Destiny. London: Allen Lane (Penguin). pp.707, 708. ISBN978-0-241-20563-1.
↑ Lavery, Brian (2007). Churchill Goes to War: Winston's Wartime Journeys. Annapolis, Maryland: The Naval Institute Press. p.94. ISBN978-1-59114-103-7.
↑ Johnston, Jeff (July 2007). "Project Update"(PDF). Clipper Discovery Update: Underwater Admiralty Sciences Newsletter. pp.1, 9. Archived from the original(PDF) on September 30, 2011. Retrieved September 16, 2009.
Hardesty, Von (2003). Air Force One: The Aircraft that Shaped the Modern Presidency. Chanhassen, Minnesota: Northword Press. ISBN1-55971-894-3.
Jablonski, Edward (1972). Sea Wings: The Romance of the Flying Boats (Hardcover). New York: Doubleday. ISBN9780385069465.
Klaás, M. D. (December 1989). "Clipper Across the Pacific, Part One". Air Classics. 25 (12).
Klaás, M. D. (January 1990). "Clipper Across the Pacific, Part Two". Air Classics. 26 (1).
Klaás, M. D. (February 1993). "Clipper Flight 9035". Air Classics. 29 (2).
Klaás, M. D. (June 1969). "The Incredible Clippers". Air Classics. 5 (5).
Klaás, M. D. (April 1991). "When the Clippers Went to War". Air Classics. 27 (4).
Trautman, James (2011). Pan American Clippers: The Golden Age of Flying Boats (Softcover). Erin, Ontario, Canada: Boston Mills Press. ISBN978-1-55407-894-3.
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