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Boeing 307

Boeing 307

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The Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

 Model 307 Stratoliner
was the first commercial transport aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 with a pressurized
Cabin pressurization
Cabin pressurization is the pumping of compressed air into an aircraft cabin to maintain a safe and comfortable environment for crew and passengers when flying at altitude.-Need for cabin pressurization:...

 cabin. This feature allowed the plane to cruise at an altitude of 20,000 ft (6,000 m), well above weather
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...

 disturbances. The pressure differential was 2.5 psi (17 kPa), so at 14,700 ft (4,480 m) the cabin altitude was 8,000 ft (2,440 m). The Model 307 had capacity for a crew of five 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
Flight engineer
Flight engineers work in three types of aircraft: fixed-wing , rotary wing , and space flight .As airplanes became even larger requiring more engines and complex systems to operate, the workload on the two pilots became excessive during certain critical parts of the flight regime, notably takeoffs...

 as a crew member (several flying boats had included a flight engineer position earlier).

Development and design


In 1935, Boeing designed a four-engined airliner
Airliner
An airliner is a large fixed-wing aircraft for transporting passengers and cargo. Such aircraft are operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an aircraft intended for carrying multiple passengers in commercial...

 based on its B-17 heavy bomber (or Boeing Model 299), the Model 307. It combined the wings, tail, undercarriage and engines of the B-17C with a new, circular section fuselage designed to allow pressurization.

The first order, for two (soon increased to six) Model 307s, was placed by Pan American Airways
Pan American World Airways
Pan American World Airways, commonly known as Pan Am, was the principal and largest international air carrier in the United States from 1927 until its collapse on December 4, 1991...

 in 1937, shortly followed by another for six from Transcontinental & Western Air
Trans World Airlines
Trans World Airlines was an American airline that existed from 1925 until it was bought out by and merged with American Airlines in 2001. It was a major domestic airline in the United States and the main U.S.-based competitor of Pan American World Airways on intercontinental routes from 1946...

 (TWA), prompting Boeing to start production of an initial batch of Model 307s.

C-75 conversion


At the time the US entered World War II in December 1941, flying across the oceans was a rare luxury. But the war required government and military officials to travel across the oceans, and most of the four-engined commercial long-range aircraft were put to this use: Pan Am's 14 flying boats and TWA
Twa
The Twa are any of several hunting peoples of Africa who live interdependently with agricultural Bantu populations, and generally hold a socially subordinate position: They provide the farming population with game in exchange for agricultural products....

's 5 Boeing 307 landplanes. Additional fuel tanks were added to the 307s to give them the extra range required. The converted 307s were designated C-75 by the military. Before WW2 ended their production, ten Boeing 307 commercial transports, named Stratoliners, had been built. TWA bought five and flew domestic routes between New York and Los Angeles for 18 months until the Army purchased them following the Japanese attack on Pearl Harbor. The intended wartime use was long-range transatlantic flight with a payload of VIPs or critical cargo. TWA converted their five Stratoliners for military service in January 1942, and its Intercontinental Division (ICD) then operated these C-75's under contract to the Army's Air Transport Command (ATC) until July 1944. These were the only commercial landplanes able to cross the Atlantic with a payload until the arrival of the C-54 Skymaster
C-54 Skymaster
The Douglas C-54 Skymaster was a four-engined transport aircraft used by the United States Army Air Forces and British forces in World War II and the Korean War. Besides transport of cargo, it also carried presidents, British heads of government, and military staff...

 in November 1942.

The Boeing 307 was based on the B-17C with a different fuselage of circular cross section of 138 in (351 cm) diameter. Conversion to 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 fuel tanks. The landing gear was strengthened, the maximum take-off weight
Maximum Take-Off Weight
The Maximum Takeoff Weight or Maximum Takeoff Mass of an aircraft is the maximum weight at which the pilot of the aircraft is allowed to attempt to take off, due to structural or other limits. The analogous term for rockets is Gross Lift-Off Mass, or GLOW...

 was increased from 45000 to 56000 lb (20,411.7 to 25,401.2 kg)), and the exterior was painted olive drab.

Operational history


The maiden flight of the first Boeing 307 (not a prototype, as it was planned to be delivered to Pan Am following testing and certification), registration
Aircraft registration
An aircraft registration is a unique alphanumeric string that identifies a civil aircraft, in similar fashion to a licence plate on an automobile...

 NX 19901 took place from Boeing Field
Boeing Field
Boeing Field, officially King County International Airport , is a two-runway airport owned and run by King County, Washington, USA. In promotional literature, the airport is frequently referred to as KCIA, but this is not the airport identifier. The airport has some passenger service, but is mostly...

, Seattle on December 31, 1938. It crashed, however, on March 18, 1939, while being demonstrated to representatives of KLM. At the time, the aircraft's performance with two engines inoperative on one side of the aircraft was being demonstrated. When the engines were shut down, the pilot deflected the rudder to maximum deflection to counter the resulting yaw. The aircraft then experienced "rudder lock", where the hinge moments on the rudder prevented it from being centered. As a result, the aircraft went into a spin
Spin (flight)
In aviation, a spin is an aggravated stall resulting in autorotation about the spin axis wherein the aircraft follows a corkscrew downward path. Spins can be entered intentionally or unintentionally, from any flight attitude and from practically any airspeed—all that is required is sufficient yaw...

 and crashed. The ten people on board, including KLM test pilot Albert von Baumhauer, Boeing test pilot Julius Barr, Boeing Chief Aerodynamcist Ralph Cram, Boeing Chief Engineer Earl Ferguson and a TWA representative were killed. Subsequent wind tunnel testing showed that the addition of a dorsal fin ahead of the vertical tail would prevent "rudder lock" and this was incorporated into the design.

The first delivery to a customer was to multi-millionaire Howard Hughes
Howard Hughes
Howard Robard Hughes, Jr. was an American business magnate, investor, aviator, engineer, film producer, director, and philanthropist. He was one of the wealthiest people in the world...

, who purchased one to carry out a round-the-world flight, hoping to break his own record of 91 hours 14 minutes set between July 10–14, 1938, in a Lockheed 14
Lockheed Model 14 Super Electra
|-See also:-References:NotesBibliography* Francillon, René J. Lockheed Aircraft since 1913. Annapolis: Naval Institute Press, 1987. ISBN 0-85177-835-6.-External links:*...

. Hughes' Boeing 307 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. It later had the extra fuel tanks removed, was fitted with much more powerful Wright R-2600
Wright R-2600
|-See also:-Bibliography:* Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1998. ISBN 0-517-67964-7-External links:...

 engines, and was transformed into a luxurious "flying penthouse" for Hughes, although it was little used, being sold to oil tycoon Glenn McCarthy
Glenn McCarthy
Glenn Herbert McCarthy was a wildcatter and a charismatic 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...

 in 1949.

Deliveries to Pan-Am started in March 1940, with TWA receiving its first aircraft in April. TWA's aircraft were used on services between Los Angeles
Los Ángeles
Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...

 and New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

, while Pan-Am's aircraft flew routes down to Latin America
Latin America
Latin America is a region of the Americas where Romance languages  – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...

. In all, only 10 aircraft were built, with three being delivered to Pan-Am and five to TWA, together with the one aircraft for Howard Hughes.

On the entry of the United States into World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 following the Attack on Pearl Harbor
Attack on Pearl Harbor
The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...

, Pan-Am continued operating its Stratoliners on routes to Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, but under direction of the Army Air Force, while TWA's aircraft were sold to the U.S. government, being designated Boeing C-75 and operated by the United States Army Air Forces
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....

 (although normally still flown by TWA crews).

The U.S. Army returned the five C-75s to TWA in 1944, and they were sent to Boeing for extensive overhauls and rebuilding. Boeing replaced the wings and horizontal tail with that from the B-17G, while more powerful engines were fitted and the electrical system was completely replaced by one based on that of the B-29 Superfortress
B-29 Superfortress
The B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing that was flown primarily by the United States Air Forces in late-World War II and through the Korean War. The B-29 was one of the largest aircraft to see service during World War II...

. Passenger capacity was increased from 33 to 38. The rebuild cost TWA a total of $2 million for the five aircraft, which re-entered passenger service on April 1, 1945. Although TWA was now committed to the larger and faster Lockheed Constellation
Lockheed Constellation
The Lockheed Constellation was a propeller-driven airliner powered by four 18-cylinder radial Wright R-3350 engines. It was built by Lockheed between 1943 and 1958 at its Burbank, California, USA, facility. A total of 856 aircraft were produced in numerous models, all distinguished by a...

, the Stratoliners remained in use, being transferred to regional services, until withdrawn and sold in April 1951.

TWA's aircraft were purchased by the French airline Aigle Azur
Aigle Azur
Société Aigle Azur Transports Aériens is an airline based in Tremblay-en-France, France, near Paris. It operates domestic scheduled passenger services and international services to Algeria, Morocco, Tunisia in North Africa as well as Portugal, Italy and Mali. It also operates charter, cargo and wet...

, who used them for scheduled flights from France to North and Central Africa, and later to French Indo-China. The 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 disposed of its unmodified Stratoliners earlier than TWA, with them being sold to a number of small operators. One aircraft was purchased by the Haitian Air Force
Armed Forces of Haiti
The Armed Forces of Haiti, , consisted of the Haitian Army, Haitian Navy , Haitian Coast Guard, the Haitian Air Force, and some police forces . The Army was always the dominant service with the others serving primarily in a support role...

, being fitted out as a Presidential transport for Papa Doc Duvalier
François Duvalier
François Duvalier was the President of Haiti from 1957 until his death in 1971. Duvalier first won acclaim in fighting diseases, earning him the nickname "Papa Doc" . He opposed a military coup d'état in 1950, and was elected President in 1957 on a populist and black nationalist platform...

. This aircraft was later returned to the United States and was purchased by the Smithsonian Museum.

C-75


Two main routes were flown: Washington, D.C., to Cairo across the South Atlantic, and New York to Scotland across the North Atlantic. They often flew non-stop the 2,125 statute miles (3,415 km) between Gander, Newfoundland and Prestwick
Prestwick
Prestwick is a town in South Ayrshire on the south-west coast of Scotland, about south-west of Glasgow. It adjoins the larger town of Ayr, the centre of which is about south...

, Scotland in the north, and the 2,550 statute miles (4,100 km) between Natal
Natal, Rio Grande do Norte
-History:The northeastern tip of South America, Cabo São Roque, to the north of Natal and the closest point to Europe from Latin America, was first visited by European navigators in 1501, in the 1501–1502 Portuguese expedition led by Amerigo Vespucci, who named the spot after the saint of the day...

, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 and Accra
Accra
Accra is the capital and largest city of Ghana, with an urban population of 1,658,937 according to the 2000 census. Accra is also the capital of the Greater Accra Region and of the Accra Metropolitan District, with which it is coterminous...

, Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...

 in the south. These were very long flights for the time. After July 1942, a refueling stop at Ascension Island
Ascension Island
Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around from the coast of Africa and from the coast of South America, which is roughly midway between the horn of South America and Africa...

 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 aircraft 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. The restoration included new B-17G Flying Fortress wings and engines, horizontal stabilizer moved three feet (0.9 m) aft, and B-29-type electronics. TWA then restyled the interior cabin in two sections, 10 seats forward and 28 aft.

Variants


307
Wright Cyclone GR-1820-G102 engines with single speed supercharger. 5 crew

307B
Wright Cyclone GR-1820-G105A engines with two speed supercharger for better high altitude performance. 7 crew

C-75
Five Trans World 307Bs impressed into service with the USAAF as military transports, the cabin pressurisation was removed.

307B-1
Following military service the C-75s were overhauled and fitted with B-17G wings, a larger B-17G tailplane, four Wright Cyclone GR-1820-G606 engines.

Civilian operators


  • Aigle Azur
    Aigle Azur
    Société Aigle Azur Transports Aériens is an airline based in Tremblay-en-France, France, near Paris. It operates domestic scheduled passenger services and international services to Algeria, Morocco, Tunisia in North Africa as well as Portugal, Italy and Mali. It also operates charter, cargo and wet...

     bought in 1951 ex-TWA aircraft with new engines and wings replaced with B-17G ones

 Laos
  • Royal Air Laos received ex-Aigle Azur aircraft

 United States
  • Howard Hughes
    Howard Hughes
    Howard Robard Hughes, Jr. was an American business magnate, investor, aviator, engineer, film producer, director, and philanthropist. He was one of the wealthiest people in the world...

     bought 1 aircraft
  • Pan Am received 3 aircraft
  • TWA
    Twa
    The Twa are any of several hunting peoples of Africa who live interdependently with agricultural Bantu populations, and generally hold a socially subordinate position: They provide the farming population with game in exchange for agricultural products....

     received 5 aircraft

Military operators


  • Haitan Air Force
    Armed Forces of Haiti
    The Armed Forces of Haiti, , consisted of the Haitian Army, Haitian Navy , Haitian Coast Guard, the Haitian Air Force, and some police forces . The Army was always the dominant service with the others serving primarily in a support role...


 United States
  • United States Army Air Forces
    United States Army Air Forces
    The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....

    , the five TWA 307Bs were impressed into service and designated as C-75s. The three Pan Am 307s were also operated for the USAAF during the second world war but retained civil registrations and were not re-designated.

Survivors


The only surviving Boeing Model 307 (NC19903) delivered in the second quarter of 1940, operated by Pan Am, is preserved in flying condition at the Smithsonian Museum's Steven F. Udvar-Hazy Center
Steven F. Udvar-Hazy Center
The Steven F. Udvar-Hazy Center is the Smithsonian National Air and Space Museum 's annex at Washington Dulles International Airport in the Chantilly area of Fairfax County, Virginia, United States....

. On March 28, 2002, this particular aircraft was subject to a dramatic crash in which it ditched
Water landing
A water landing is, in the broadest sense, any landing on a body of water. All waterfowl, those seabirds capable of flight, and some human-built vehicles are capable of landing in water as a matter of course....

 into Elliott Bay
Elliott Bay
Elliott Bay is the body of water on which Seattle, Washington, is located. A line drawn from Alki Point in the south to West Point in the north serves to mark the generally accepted division between the bay and the open sound...

 in Seattle, Washington
Seattle, Washington
Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...

, on what was to be its last flight before heading to the Smithsonian. Despite the incident, it was again restored, flew to the Smithsonian and is now on display.

The fuselage of Howard Hughes' personal 307 survives, although it has been converted into a house boat.

Specifications (Boeing 307)



See also



External links