Boeing 307 Stratoliner

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.

## Development and design

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 . It was designed so that the plane could be pressurized.

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.

### C-75

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 b

n New York and Los Angeles for 18 months until the Army bought their planes. TWA changed their 307s to C-75s in January 1942. 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  fuel tanks were put onto the plane. The landing gear was made stronger and the maximum take-off weight was made bigger (from ). The outside was painted olive drab.

## History

The first Boeing 307 Stratoliner flew from Boeing Field, Seattle on December 31, 1938. 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.

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.

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. 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.

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. TWA switched to the Lockheed Constellation, but the 307s were used until April, 1951.

TWA sold its Stratoliners to Aigle Azur.

### C-75

The C-75 flew two main routes: Washington, D.C. to Cairo and New York to Scotland. 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. I

## Different types of Boeing 307

- 307
- had Wright Cyclone GR-1820-G102 engines and five crew
- 307B
- had Wright Cyclone GR-1820-G105A engines and seven crew
- C-75
- Boeing 307s used by the U.S. military

### Civilians

- Aigle Azur
- Royal Air Laos
- Howard Hughes bought one aircraft.
- Pan Am got three aircraft.
- TWA got five aircraft.

### Military

- Haitan Air Force
- United States Army Air Forces

## Boeing 307s which still exist

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.

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

### Bibliography

- Bowers, Peter M. _Boeing Aircraft since 1916_. London: Putnam, Third edition, 1989. .
- 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. .
- Taylor, H.A. "Ten Big Boeings ... The Stratoliner Story". _Air Enthusiast_, Ten, July–September 1979, pp. 58–67. Bromley, UK: Fine Scroll.

## Other websites

- Video Courtesy of *Bomberguy Aviation Historian
- Coast to Coast on Four Motors September 1940 Popular Mechanics
- History of the Boeing 307 by Boeing Historical Division

## Infobox (aircraft begin)

- **name**: Boeing 307 / C-75
- **image**: File:Boeing_307_Udvar_Hazy.jpg
- **caption**: A Boeing 307 at the Steven F. Udvar-Hazy Center


## Infobox (aircraft type)

- **type**: Airliner
- **manufacturer**: Boeing
- **first flight**: 31 December 1938
- **introduced**: 8 July 1940
- **retired**: 1975
- **number built**: 10
- **status**: Retired
- **primary user**: TWA
- **more users**: Pan Am
 United States Army Air Forces
- **unit cost**: $315,000 (in 1937)
- **developed from**: Boeing B-17 Flying Fortress