Boeing 307
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| Boeing 307 | |
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| A restored Boeing 307 ex-Pan Am on display at the Steven F. Udvar-Hazy Center | |
| Role | Airliner |
| Manufacturer | Boeing |
| First flight | 31 December 1938 |
| Introduced | 8 July 1940 |
| Retired | 1970s |
| Primary users | TWA Pan Am |
| Number built | 10 |
| Unit cost | $315,000 (in 1937 when ordered) |
| Developed from | Boeing B-17 Flying Fortress |
| Variants | Boeing C-75 |
The Boeing Model 307 Stratoliner was the first commercial transport aircraft with a pressurized cabin. This feature allowed the plane to cruise at an altitude of 20,000 ft (6,000 m), well above weather 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 plane to include a flight engineer as a crew member.
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Development and design
In 1935, Boeing designed a four-engined airliner 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 in 1937, shortly followed by one for six from Transcontinental & Western Air (TWA), prompting Boeing to start production of an initial batch of Model 307s.
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 NX 19901 took place from Boeing Field, Seattle on December 31, 1938. It crashed, however, on March 18, 1939 while being demonstrated to representatives of KLM, breaking up during spin recovery.
The first delivery to a customer was to multi-millionaire Howard Hughes, 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. 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 engines and was transformed into a luxurious "flying penthouse" for Hughes, although it was little used, being sold to oil tycoon Glenn McCarthy 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 and New York, while Pan-Am's aircraft flew routes down to Latin America. 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 following the Attack on Pearl Harbor, Pan-Am continued operating its Stratoliners on routes to Central and South America, but under direction of the Army Air Force, while TWA's aircraft were sold to the US Government, being designated Boeing C-75 and operated by the United States Army Air Forces (although normally still flown by TWA crews).
The US 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. 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, 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, 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, being fitted out as a Presidential transport for Papa Doc Duvalier. This aircraft was later returned to the United States and was purchased by the Smithsonian Museum.
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 and converted to 307B-1 standard with B-17G wings, a larger tailplane, four Wright Cyclone GR-1820-G606 engines and cabin pressurisation removed.
Operators
Civilian operators
- Aigle Azur bought in 1951 ex-TWA aircraft with new engines and wings replaced with B-17G ones.
- Air Laos received ex-Aigle Azur aircraft.
- Pan Am received 3 aircraft.
- TWA received 5 aircraft.
- Howard Hughes bought 1 aircraft.
Military operators
- United States Army Air Force operated Boeing 307s designated as C-75
Survivors
The only surviving Boeing Model 307 (NC19903), operated by Pan Am, is preserved in flying condition at the Smithsonian Museum's Steven F. Udvar-Hazy Center. On March 28, 2002 this particular aircraft was subject to a dramatic crash in which it ditched 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, 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)
Data from Jane's AWA 1942 (apart from wing area and loading)
General characteristics
- Crew: 5, including two pilots and flight engineer
- Capacity: 33 passengers in daytime, 25 by night
- Length: 74 ft 4 in (22.6 m)
- Wingspan: 107 ft 0 in (32.63 m)
- Height: 20 ft 9.5 in (6.33 m)
- Wing area: 1,486 ft² (138.0 m²)
- Empty weight: 30,000 lb (13,608 kg)
- Loaded weight: 45,000 lb (20,420 kg)
- Powerplant: 4× Wright GR-1820-G102 radials, 1,100 hp (820 kW) each
Performance
- Maximum speed: 241 mph at 6,000 ft (387 km/h at 1,830 m)
- Cruise speed: 215 mph at 10,000 ft (344 km/h at 3,050 m)
- Range: 1,750 mi (2,820 km)
- Service ceiling: 23,300 ft (7,110 m)
- Wing loading: 28 lb/ft² (138 kg/m²)
- Power/mass: 0.098 hp/lb (160 W/kg)
See also
Related development
Comparable aircraft
- Douglas DC-4
- C-46 Commando-original, pressurized, CW-20 version
References
- Notes
- ^ Boeing 307 Stratoliner entry at The Aviation History Online Museum website
- ^ a b Hardy, Air International January 1994, p.21.
- ^ a b Bowers 1989, p.231.
- ^ Ford 2004, p.55.
- ^ Taylor 1979, p.58.
- ^ Hardy, Air International January 1994, pp. 22–23.
- ^ Houston's Aviation History Timeline at The 1940 Air Terminal Museum website
- ^ Taylor 1979, pp. 58–59.
- ^ Taylor 1979, p.59.
- ^ Hardy, Air International February 1994, p.69.
- ^ Bowers 1989, pp. 234–235.
- ^ Hardy, Air International February 1994, p.70.
- ^ Hardy, Air International February 1994, pp. 70–72.
- ^ Hardy, Air International February 1994, p.71.
- ^ 4 escape injury as historic Stratoliner ditches in Elliott Bay article at the Seattle Post-Intelligencer
- ^ http://www.boeing.com/news/frontiers/archive/2003/september/i_ca.html
- ^ http://www.inhabitat.com/2009/08/20/the-cosmic-muffin-a-boat-recycled-from-howard-hughes-plane/
- Bibliography
- Bowers, Peter M. Boeing Aircraft since 1916. London:Putnam, Third edition, 1989. ISBN 0-85177-804-6.
- Bridgman, L. (1942).Jane's All the World's Aircraft 1942. London: Sampson Low, Marston & Co.
- Ford, Daniel. "First and Last 'Strat':Boeing's Model 307 and its Survivors". Air Enthusiast, No. 110, March/April 2004. Stamford, UK:Key Publishing. ISSN 0143-5450. pp. 54–60.
- Hardy, Mike. "The Stratoliner Story (Part 1)." Air International, January 2004, Vol 46 No 1. Stamford, UK:Key Publishing. ISSN 0306-5634. pp. 21–24.
- Hardy, Mike. "The Stratoliner Story (Part 2)." Air International, February 2004, Vol 46 No 2. Stamford, UK:Key Publishing. ISSN 0306-5634. pp. 69–72.
- Taylor, H.A. "Ten Big Boeings...The Stratoliner Story". Air Enthusiast, Ten, July–September 1979. Bromley, UK:Fine Scroll. pp. 58–67.
External links
- 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
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