Boeing 307 Stratoliner

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Boeing 307 / C-75
A Boeing 307 at the Steven F. Udvar-Hazy Center
Role Airliner
Manufacturer Boeing
First flight 31 December 1938
Introduction 8 July 1940
Retired 1975
Status Retired
Primary users TWA
Pan Am
United States Army Air Forces
Number built 10
Unit cost
$315,000 (in 1937)[1]
Developed from Boeing B-17 Flying Fortress

The Boeing Model 307 Stratoliner was an airliner which was made by Boeing. It was the first airliner to have a pressurized cabin. This meant that the Boeing 307 could fly at 20,000 ft (6,000 m), which is above most weather. If the plane was at 14,700 ft (4,480 m), it would be like 8,000 ft (2,440 m) inside the cabin. The Model 307 carried five crew and 33 passengers. The cabin was nearly 12 ft (3.6 m) across. It was the first plane which took off from land to have a flight engineer.[1]

Development and design[change | change source]

In 1935 Boeing designed an airliner with four engines. It was based on the Boeing B-17 Flying Fortress. This airliner was called the Model 307. It had the same wings, tail, rudder, landing gear and engines as the B-17C. However, the middle of the plane was a circle. Its diameter was 138 in (351 cm).[2] It was designed so that the plane could be pressurized.[3]

The first order was made in 1937 by Pan American Airways. Pan Am then ordered more. Transcontinental & Western Air (TWA) ordered five. Boeing then started making the plane.[3][4]

C-75[change | change source]

When the U.S. joined World War II in December 1941, it was thought to be a luxury to fly. The war meant that government and military officers needed to fly long distances. Planes like Pan Am's 14 flying boats and TWA's five Boeing 307s were used for this. More fuel tanks were added to allow it to fly further. Military Boeing 307s were called C-75s. Before World War II stopped them being made, 10 307s had been made for airlines. TWA flew between New York and Los Angeles for 18 months until the Army bought their planes. TWA changed their 307s to C-75s in January 1942.[5] These were the only American planes which could cross the Atlantic with cargo until the Douglas C-54 Skymaster was made in November 1942.

C-75s had the pressurization equipment removed to make the plane lighter. Some seats were taken off, and some other changes were made. Five 212.5 U.S. gal (804 L; 177 imp gal) fuel tanks were put onto the plane. The landing gear was made stronger and the maximum take-off weight was made bigger (from 45,000 to 56,000 lb (20,400 to 25,400 kg)). The outside was painted olive drab.[2]

History[change | change source]

The first Boeing 307 Stratoliner flew from Boeing Field, Seattle on December 31, 1938.[6] However, it crashed on March 18, 1939, while KLM was looking at it.

The first delivery was made to Howard Hughes. He bought one Boeing 307 to fly around the world. He wanted to do it faster than he did before. Hughes' Boeing Stratoliner had more fuel tanks. It was ready to go, but then Nazi Germany invaded Poland on September 1, 1939, so Howard Hughes did not make his flight. This 307 had its extra fuel tanks taken off. It also had more powerful engines added. It was supposed to be a "flying penthouse" for Hughes, but it was not used a lot. It was eventually sold.[7][8]

Pam Am started getting its Boeing 307s in March 1940. TWA got its first 307 in April. TWA used its 307s to fly from Los Angeles to New York City. Pan Am's flew from Miami to Latin America. Ten 307s were made. Three were given to Pan Am (named Clipper Flying Cloud, Clipper Comet, and Clipper Rainbow) and five to TWA (named Comanche, Cherokee, Zuni, Navajo, and Apache). One went to Howard Hughes. The first 307 crashed.[9]

After the United States joined World War II, Pan Am kept flying its planes to Central and South America, but the Army Air Force was in charge of them.[10] TWA's Boeing 307s were sold to the U.S. government. They were called Boeing C-75 and used by the United States Army Air Forces.[11]

The U. S. Army gave the five C-75s back to TWA in 1944. TWA sent them back to Boeing to be rebuilt. Boeing replaced the wings and put in more powerful engines. The electrics were replaced with electrics from the Boeing B-29 Superfortress. After these changes, the 307 could carry 38 passengers.[12] TWA switched to the Lockheed Constellation, but the 307s were used until April, 1951.[13]

An Aigle Azur Stratoliner at Paya Lebar in 1967

TWA sold its Stratoliners to Aigle Azur.

C-75[change | change source]

The C-75 flew two main routes: Washington, D.C. to Cairo and New York to Scotland.[14] They sometimes flew from Gander, Newfoundland to Prestwick, Scotland and between Natal, Brazil and Accra, Ghana. After July 1942, they could stop to refuel at Ascension Island.[15] I

Different types of Boeing 307[change | change source]

Passengers on a Pan Am Boeing 307
Royal Air Lao Boeing 307 Stratoliner
had Wright Cyclone GR-1820-G102 engines and five crew
had Wright Cyclone GR-1820-G105A engines and seven crew
Boeing 307s used by the U.S. military

Users[change | change source]

Civilians[change | change source]

 United States

Military[change | change source]

 United States

Boeing 307s which still exist[change | change source]

Boeing 307 (NC 19903) in Elliott Bay, Seattle, March 28, 2002

The only Boeing 307 Stratoliner which still exists is at the Smithsonian Museum's Steven F. Udvar-Hazy Center. On March 28, 2002, this plane was damaged a lot when it ditched in Elliott Bay in Seattle, Washington. That was its last flight before it went to the Smithsonian.[16]

The main part of Howard Hughes' 307 also still exists, but it is now a house boat.[17]

Details (Boeing 307)[change | change source]

Data from Jane's AWA 1942 (apart from wing area and loading)

General characteristics

  • Crew: five: two pilots, flight engineer, two cabin crew
  • Capacity: 38 passengers in daytime, 25 by night
  • Length: 74.3 ft (22.6 m)
  • Wingspan: 107 ft (33 m)
  • Height: 20.79 ft (6.34 m)
  • Wing area: 1,486[4] sq ft (138.1 m2)
  • Empty weight: 30,000 lb (13,608 kg)
  • Gross weight: 45,000 lb (20,412 kg)
  • Powerplant: 4 × Wright GR-1820-G102A radial engines, 1,100 hp (820 kW) each


  • Maximum speed: 241 mph (388 km/h; 209 kn)
  • Cruise speed: 215 mph (346 km/h; 187 kn)
  • Range: 1,750 mi (1,521 nmi; 2,816 km)
  • Service ceiling: 23,300 ft (7,100 m)
  • Wing loading: 28 lb/sq ft (140 kg/m2)
  • Power/mass: 0.098 hp/lb

Related pages[change | change source]

Aircraft related to this one

References[change | change source]

Notes[change | change source]

  1. 1.0 1.1 "Boeing 307 Stratoliner entry at." The Aviation History Online Museum. Retrieved: January 28, 2012.
  2. 2.0 2.1 Betts, Ed. "The Boeing Stratoliners and TWA." American Aviation Historical Society Journal, Volume 38, Issue 3, 1993.
  3. 3.0 3.1 Hardy, Air International January 1994, p. 21.
  4. 4.0 4.1 Bowers 1989, p. 231.
  5. Jane's Fighting Aircraft of World War II. London: Random House, 1989. ISBN 1-85170-199-0.
  6. Ford 2004, p. 55.
  7. Hardy, Air International, January 1994, pp. 22–23.
  8. "Houston's Aviation History Timeline." Archived 2006-10-08 at the Wayback Machine The 1940 Air Terminal Museum. Retrieved: January 28, 2012.
  9. Munson 1972, p. 182.
  10. Taylor 1979, p.59.
  11. Hardy, Air International February 1994, p. 69.
  12. Bowers 1989, pp. 234–235.
  13. Hardy, Air International February 1994, p. 70.
  14. Berry, Peter. "Transatlantic Flight 1938-1945 (Part I 1938-1943)." AAHS Journal, Volume 40, Issue 2, 1995.
  15. Berry, Peter. "Transatlantic Flight 1938-1945 (Part II 1943-1945)." AAHS Journal, Volume 40, Issue 3, 1995.
  16. "4 escape injury as historic Stratoliner ditches in Elliott Bay." Seattle Post-Intelligencer (original post). Retrieved: June 4, 2012.
  17. "Green Design Will save the World: The Cosmic Muffin: A Boat Recycled From Howard Hughes’ Plane." Inhabitat. Retrieved: December 29, 2012.

Bibliography[change | change source]

  • Bowers, Peter M. Boeing Aircraft since 1916. London: Putnam, Third edition, 1989. ISBN 0-85177-804-6.
  • Bridgman, L. Jane's All the World's Aircraft 1942. London: Sampson Low, Marston & Co., 1942.
  • Ford, Daniel. "First and Last 'Strat': Boeing's Model 307 and its Survivors". Air Enthusiast, No. 110, March/April 2004, pp. 54–60. Stamford, UK: Key Publishing. ISSN 0143-5450.
  • Hardy, Mike. "The Stratoliner Story (Part 1)." Air International, Vol. 46, No 1, January 2004, pp. 21–24. Stamford, UK: Key Publishing. ISSN 0306-5634.
  • Hardy, Mike. "The Stratoliner Story (Part 2)." Air International, Vol. 46, No 2, February 2004, pp. 69–72. Stamford, UK: Key Publishing. ISSN 0306-5634.
  • Munson, Kenneth. Bombers in Service, Patrol and Transport Aircraft Since 1960. London: The Macmillan Co., 1972. ISBN 978-0-71370-586-7.
  • Taylor, H.A. "Ten Big Boeings ... The Stratoliner Story". Air Enthusiast, Ten, July–September 1979, pp. 58–67. Bromley, UK: Fine Scroll.

Other websites[change | change source]