The Boeing Model 307 Stratoliner was a commercial transport aircraft that entered service in 1938. It was the first to offer a pressurized cabin, allowing it to cruise at an altitude of 20,000 ft (6,000 m), well above many weather disturbances. The pressure differential was 2.5 psi (17 kPa), so at 14,700 ft (4,480 m) the cabin air pressure was equivalent to an altitude of 8,000 ft (2,440 m). The Model 307 had capacity for a crew of six and 33 passengers. The cabin was nearly 12 ft (3.6 m) across. It was the first land-based aircraft to include a flight engineer as a crew member (several flying boats had included a flight engineer position earlier). In addition to its civilian service it was also flown as the Boeing C-75 Stratoliner by the United States Army Air Forces, who used it as a long-range cargolift aircraft.
|Boeing 307 Stratoliner|
|A restored (ex-Pan Am) Boeing 307 on display at the Steven F. Udvar-Hazy Center|
|First flight||December 31, 1938|
|Introduction||July 4, 1940 with Pan American Airways|
Pan American Airways
United States Army Air Forces
$315,000 in 1937 (equivalent to $5.5 million today)
|Developed from||Boeing B-17 Flying Fortress|
In 1935, Boeing designed a four-engine airliner based on its B-17 heavy bomber (Boeing Model 299), then in development, calling it the Model 307. It combined the wings, tail, rudder, landing gear, and engines from their production B-17C with a new, circular cross-section fuselage of 138 in (351 cm) diameter, designed to allow pressurization.
The first order, for two 307s (named Stratoliners), was placed in 1937 by Pan American Airways. Pan Am soon increased this to six, and a second order for five from Transcontinental & Western Air (TWA) prompted Boeing to begin production on an initial batch of the airliner.
At the time the United States entered World War II in December 1941, flying across oceans was a rare luxury. The war required government and military officials to do so, and most four-engined long-range commercial aircraft, including Pan American Airways' 14 flying boats and TWA's five Boeing 307s, were pressed into service. Additional fuel tanks were added to give them the extra range required; once converted they were designated C-75 for military use. Before World War II ended their production, ten commercial 307s had been built. TWA flew domestic routes between New York and Los Angeles for 18 months until the Army purchased their Stratoliners for wartime use as long-range, transatlantic transports for various VIPs or critical cargo on 26 January 1942. TWA converted their 307s to military service in January 1942, and its Intercontinental Division (ICD) then operated these C-75s under contract to the Army's Air Transport Command (ATC) until July 1944. These were the only U. S. built commercial aircraft able to cross the Atlantic with a payload until the arrival of the Douglas C-54 Skymaster in November 1942.
Conversion to the C-75 included removal of the pressurization equipment to save weight, removal of the forward four (or five) of nine reclining seats along the port side, and alteration of the two forward Pullman-like compartments (of four) starboard of the left-of-centerline aisle. Space was thus provided for crew requirements on extremely long flights and for the addition of five 212.5 U.S. gal (804 L; 177 imp gal) fuel tanks. The landing gear was strengthened, the maximum takeoff weight was increased from 45,000 to 56,000 lb (20,400 to 25,400 kg), and the exterior was painted military olive drab.
The maiden flight of the first Boeing 307 Stratoliner (not a prototype, as it was planned to be delivered to Pan Am following testing and certification), registration NX 19901 took place from Boeing Field, Seattle on December 31, 1938.
This aircraft crashed on March 18, 1939, while being demonstrated to representatives of KLM. After takeoff the aircraft climbed to an altitude of 11,000 feet. At this altitude, longitudinal stability tests were made. The next tests, as outlined by the flight plan, were side-slip tests. The aircraft went into an inadvertent spin subsequent to a stall at an altitude of approximately 11,000 feet. It made two to three turns in the spin, during which the engines were used to aid recovery. In recovering from the dive subsequent to the spin, the wings and horizontal tail surfaces failed upward apparently due to air loads in excess of those for which the aircraft was designed. The ten people aboard, including the KLM technical director, a representative of the Dutch Air Ministry, a Boeing test pilot, the Boeing Chief Aerodynamicist, the Boeing Chief Engineer, and a TWA representative were killed. Subsequent wind tunnel testing showed that the addition of an extended dorsal fin ahead of and attached to the vertical tail prevented rudder lock. This was incorporated into the 307's rudder redesign, while also being incorporated in Boeing's rear fuselage redesign for their models "E" through "G" B-17 bomber.
The first delivery to a customer was to multi-millionaire Howard Hughes, who bought one 307 for a round-the-world flight, hoping to break his own record of 91 hours 14 minutes set from July 10–14, 1938 in a Lockheed 14. Hughes' Boeing Stratoliner was fitted with extra fuel tanks and was ready to set out on the first leg of the round-the-world attempt when Nazi Germany invaded Poland on September 1, 1939, causing the attempt to be abandoned. This 307 later had the extra fuel tanks removed, was fitted with much more powerful Wright R-2600 engines, and was transformed into a luxurious "flying penthouse" for Hughes, although it was little used, eventually being sold to oil tycoon Glenn McCarthy in 1949.
Deliveries to Pan Am started in March 1940, with TWA receiving its first 307 in April. TWA's Stratoliners flew three-stop flights between Los Angeles and New York while Pan Am's flew from Miami to Latin America. Ten 307s were built, three being delivered to Pan-Am (Clipper Flying Cloud, Clipper Comet, and Clipper Rainbow) and five to TWA (Comanche, Cherokee, Zuni, Navajo, and Apache) with one aircraft going to Hughes.
On the entry of the United States into World War II, Pan Am continued operating its Stratoliners on routes to Central and South America, but under direction of the Army Air Forces, while TWA's 307s were sold to the United States government, being designated Boeing C-75 and operated by the United States Army Air Forces (although normally still flown by TWA crews).
The Army returned its five C-75s to TWA in 1944, who sent them back to Boeing for rebuilding. Boeing replaced the wings and horizontal tail with those from the B-17G, while more powerful engines were fitted and the electrical system was replaced with one based on the B-29 Superfortress. Passenger capacity was increased from 33 to 38. The total rebuilding cost to TWA was $2 million; the five aircraft re-entered passenger service on April 1, 1945. Although TWA was committed to the larger and faster Lockheed Constellation, it kept the Stratoliners until April 1951.
TWA sold its Stratoliner fleet to the French airline Aigle Azur who used them on scheduled flights from France to North and Central Africa, and later to French Indo-China. These 307s were later transferred to Aigle Azur's Vietnamese subsidiary and were used by a number of airlines in South East Asia, with at least one aircraft remaining in commercial use until 1974.
Pan Am flew its unmodified 33-passenger Stratoliners between Miami and Havana until 1947, then sold them to small operators. One aircraft was purchased by the Haitian Air Force, being fitted as a Presidential transport for François "Papa Doc" Duvalier. This aircraft later returned to the U.S. and was purchased by the Smithsonian Museum.
Two main routes were flown: Washington, D.C., to Cairo across the South Atlantic, and New York to Prestwick, Scotland, across the North Atlantic. They often flew non-stop the 2,125 statute miles (3,415 km) between Gander, Newfoundland and Prestwick, Scotland in the north, and the 2,550 statute miles (4,100 km) between Natal, Brazil and Accra, Ghana in the south. After July 1942 a refueling stop at Ascension Island was an option in the south. In the north, stops at Iceland or Greenland were often necessary, especially flying westbound against the prevailing winds. As C-54s took over the Gander to Prestwick route, the C-75s operated a Marrakech-to-Prestwick service out over the Atlantic.
In April 1945, the five C-75s were returned to TWA, having been restored by Boeing and recertified by the CAA as SA-307B-1 civilian transports with their old registration numbers. TWA then restyled the interior cabin in two sections, ten seats forward and 28 aft.
According to the Aviation Safety Network, the Boeing 307 was involved in eight hull-loss incidents for a total of 54 fatalities.
The only surviving Boeing 307 Stratoliner (NC19903) is preserved in flying condition at the Smithsonian Museum's Steven F. Udvar-Hazy Center. On March 28, 2002, this aircraft crashed into Elliott Bay in Seattle, Washington, on what was to be its last flight before heading to the Smithsonian. Despite the incident, it was again restored, flown to the Smithsonian, and is now on display.
The fuselage of Howard Hughes' personal 307 also survives, although it has been converted into a houseboat. The aircraft was awaiting restoration at Fort Lauderdale International Airport in the early 1960s when it was severely damaged in a hurricane after its tiedowns failed and it was blown into a stand of trees. The aircraft languished for nearly a year before being removed and longer still until later salvaged for its conversion into the house boat. The interior is notable for the original finishes and fitments added by Howard Hughes.
Data from Jane's AWA 1942 (apart from wing area and loading)
Aircraft of comparable role, configuration and era
Aerospace is the human effort in science, engineering, and business to fly in the atmosphere of Earth (aeronautics) and surrounding space (astronautics). Aerospace organizations research, design, manufacture, operate, or maintain aircraft or spacecraft. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications.
Aerospace is not the same as airspace, which is the physical air space directly above a location on the ground. The beginning of space and the ending of the air is considered as 100 km above the ground according to the physical explanation that the air pressure is too low for a lifting body to generate meaningful lift force without exceeding orbital velocity.Airframe
The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and exclude the propulsion system.
Airframe design is a field of aerospace engineering that combines aerodynamics, materials technology and manufacturing methods with a focus on performance, as well as reliability and cost.Boeing 247
The Boeing Model 247 was an early United States airliner, considered the first such aircraft to fully incorporate advances such as all-metal (anodized aluminium) semimonocoque construction, a fully cantilevered wing and retractable landing gear. Other advanced features included control surface trim tabs, an autopilot and de-icing boots for the wings and tailplane."Ordered off the drawing board", the 247 first flew on February 8, 1933 and entered service later that year. Subsequent development in airliner design saw engines and airframes becoming larger and four-engined designs emerged, but no significant changes to this basic formula appeared until cabin pressurization and high altitude cruise were introduced in 1940, with the Boeing 307 Stratoliner.Boeing Plant 2
Boeing Plant 2 (also known as Air Force Plant 17) was a factory building which was built in 1936 by The Boeing Company in King County, Washington in the United States. By the time production ceased in the building, the plant had built half of the Boeing B-17 Flying Fortresses, the Boeing 307s, the Boeing 377s, some of the Boeing B-29 Superfortresses, Boeing B-50 Superfortresses, B-47 Stratojets, B-52 Stratofortresses, and the initial Boeing 737s. It was located between the Duwamish River and Boeing Field, to the east of the 16th Avenue South bridge, facing East Marginal Way South.Claire Egtvedt
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The Consolidated R2Y "Liberator Liner" (Consolidated Model 39) was an airliner derivative of the B-24 Liberator built for the United States Navy by Consolidated Aircraft.Douglas DC-4
The Douglas DC-4 is a four-engine (piston) propeller-driven airliner developed by the Douglas Aircraft Company. Military versions of the plane, the C-54 and R5D, served during World War II, in the Berlin Airlift and into the 1960s. From 1945, many civil airlines operated the DC-4 worldwide.Edmund T. Allen
Edmund Turney Allen (January 4, 1896 – February 18, 1943) was a pioneer of modern flight test who flew for nearly every major aircraft manufacturer and took some of the most famous planes of all time up for their first flights.Elliott Bay
Elliott Bay is a part of the Central Basin region of Puget Sound in Cascadia. It is in the U.S. state of Washington, extending southeastward between West Point in the north and Alki Point in the south. Seattle was founded on this body of water in the 1850s and has since grown to encompass it completely. The waterway it provides to the Pacific Ocean has served as a key element of the city's economy, enabling the Port of Seattle to become one of the busiest ports in the United States.Enrique Adolfo Jiménez Airport
Enrique Adolfo Jiménez Airport (Spanish: Aeropuerto Enrique Adolfo Jiménez) (IATA: ONX, ICAO: MPEJ) is an international airport located in Colón, Panama, offering scheduled airline flights to Panama City, and to other destinations. The airport is just east of Colon's harbor and cargo handling facilities.
This airport contains car rentals, a duty-free shop, restaurants, and coffee shops. The airport is located near the Sheraton Hotel and Radisson Hotel and Casino.The Tocumen VOR-DME (Ident: TUM) is located 33.2 nautical miles (61 km) east-southeast of the airport. The Enrique Jimenez VOR-DME (Ident: FNC) is located on the field.Flight engineer
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.
In earlier days, most larger aircraft were designed and built with a flight engineer's position. For U.S. civilian aircraft that require a flight engineer as part of the crew, the FE must possess an FAA Flight Engineer Certificate with reciprocating, turboprop, or turbojet ratings appropriate to the aircraft. Whereas the four-engine Douglas DC-4 did not require an FE, the FAA type certificates of subsequent four-engine reciprocating engine airplanes (DC-6, DC-7, Constellation, Boeing 307 and 377) and early three- and four-engine jets (Boeing 707, 727, early 747, DC-8, DC-10, L-1011) required flight engineers. Later three- and four-engine jets (MD-11, 747-400, and later) were designed with sufficient automation to eliminate the position.George S. Schairer
George S. Schairer (May 19, 1913 – October 28, 2004) was an aerodynamicst at Consolidated Aircraft and Boeing whose design innovations became standard on virtually all types of military and passenger jet planes.Glenn McCarthy
Glenn Herbert McCarthy (December 25, 1907 - December 26, 1988) was an American oil tycoon. The media often referred to him as "Diamond Glenn" and "The King of the Wildcatters". McCarthy was an oil prospector and entrepreneur who owned many businesses in various sectors of the economy. McCarthy founded the Shamrock Hotel in Houston, which garnered him national fame and inspired the fictional character Jett Rink in Edna Ferber's 1952 novel Giant which, in 1956, became a film, which starred James Dean in the role.Lockheed XC-35
The Lockheed XC-35 is a twin-engine, experimental pressurized airplane. It was the second American aircraft to feature cabin pressurization. It was initially described as a 'supercharged cabin' by the Army. The distinction of the world's first pressurized aircraft goes to a heavily modified Engineering Division USD-9A which flew in the United States in 1921. The XC-35 was a development of the Lockheed Model 10 Electra that was designed to meet a 1935 request by the United States Army Air Corps for an aircraft with a pressurized cabin.Propliner
A propliner is a large, propeller-driven airliner. Typically, the term is used for piston engine airliners that flew before the beginning of the jet age, not for modern turboprop airliners. With the notable exception of the de Havilland Albatross of the 1930s, which was largely fabricated of wood, propliners featured all-metal wings and structural members, retractable landing gear, and generally two or four engines.
The first propliner was the Boeing 247 (first flight 1933), with the Douglas DC-1 and Douglas DC-2 closely following in response. The most successful is the Douglas DC-3, which was produced in the thousands, and is still in widespread use; while the Dewoitine D.338 and SNCASE SE.161 Languedoc were developed in France and Germany produced the Focke-Wulf Fw 200 Condor and Junkers Ju 90. In Japan a license-built version of the Douglas DC-3 was developed as the Nakajima L2D and the smaller Mitsubishi MC-20 was locally developed. In the Netherlands Fokker, previously one of the leading manufacturers of airliners before the Boeing 247 appeared, became the European sales agent for Douglas DC-2s and DC-3s. Most British-built aircraft of the period were less advanced, such as the Avro 642 Eighteen and de Havilland Express; one exception was the Armstrong Whitworth Ensign. Other American-designed propliners included the Douglas DC-4, Douglas DC-5 and Martin 2-0-2. None of these models featured cabin pressurization.
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By the 1950s the traveling public were increasingly finding themselves being transported upon long range pressurized propliners such as the Boeing 377 Stratocruiser, Lockheed L-1049 Super Constellation and Lockheed L-1649 Starliner, or shorter ranged twin engined Martin 4-0-4 and Convair CV-240, CV-340 and CV-440 aircraft. British propliners included the Airspeed Ambassador, Vickers Viking and Handley Page Hermes, while the Canadair North Star (a development of the Douglas DC-4) was produced in Canada. The Breguet Deux-Ponts and Hurel-Dubois HD.31 were manufactured in France; and the Soviet Union produced the postwar twin-engined Ilyushin Il-12 and Ilyushin Il-14, both produced in quantity through the 1950s. Finally, the Swedish SAAB Scandia was produced in small numbers.Ralph W. Cram
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Royal Air Lao was the national air carrier of the Kingdom of Laos that operated from 1962 to 1974.Steven F. Udvar-Hazy Center
The Steven F. Udvar-Hazy Center, also called the Udvar-Hazy Center, is the Smithsonian National Air and Space Museum (NASM)'s annex at Washington Dulles International Airport in the Chantilly area of Fairfax County, Virginia, United States. It holds numerous exhibits, including the Space Shuttle Discovery, the Enola Gay, and the Gemini 7 space capsule.
The 760,000-square-foot (71,000 m2; 17-acre; 7.1 ha) facility was made possible by a $65 million gift in October 1999 to the Smithsonian Institution by Steven F. Udvar-Házy, an immigrant from Hungary and co-founder of the International Lease Finance Corporation, an aircraft leasing corporation. The main NASM building, located on the National Mall in Washington, D.C, had always contained more artifacts than could be displayed, and most of the collection had been stored, unavailable to visitors, at the Paul E. Garber Preservation, Restoration, and Storage Facility in Silver Hill, Maryland. A substantial addition to the center encompassing restoration, conservation and collection-storage facilities was completed in 2010. Restoration facilities and museum archives were moved from the museum's Garber facility to the new sections of the Udvar-Hazy Center.Tupolev ANT-53
The Tupolev ANT-53 was a late 1930s project for a passenger aircraft by the Tupolev Design Bureau.
Boeing aircraft model numbers
Boeing military aircraft
|Patrol and surveillance|
|Army/Air Force sequence|
|Revived original sequence|