Boeing Commercial aircraft

Model 307 Stratoliner (1938)

307 Startoliner (1938)

Boeing Commercial aircraft

Boeing Comercial

Model 307 Stratoliner (1938)

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Model 307 Stratoliner (1938)

The Boeing Model 307 Stratoliner was an American commercial transport aircraft that entered commercial service in July 1940. 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).[1] 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.

Operational History

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,[2] designed to allow pressurization.[3]

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. Pan Am received its initial order and TWA received its order, but only one of the second batch of four Pan Am aircraft was delivered before war intervened and put a halt to civil aircraft production.


Boeing Startoliner

Role Airliner
National origin United States
Manufacturer Boeing
First flight December 31, 1938
Introduction July 4, 1940 with Pan American Airways
Retired 1975
Status Retired
Primary users Transcontinental & Western Air
Pan American Airways
United States Army Air Forces
Number built 10
Developed from Boeing B-17 Flying Fortress


Civilian operators

 United States
  • Howard Hughes bought one aircraft (NX-19904).
  • Pan American Airways (PAA: Pan Am) received three aircraft (NC-19902/03/10).
  • Trans World Airlines (TWA) received five aircraft (NC-19905/06/07/08/09).
  • Quaker City Airways, as: N-75385 (ex-PanAm: NC-19910).
  •  United States
    United States Army Air Forces, the five TWA 307Bs were pressed into service and designated as C-75s: 42-88623/24/25/26/27. The three Pan Am 307s were also operated for the USAAF during World War II but retained civil registrations and were not redesignated.

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Boeing 307 Stratoliner (1938)

The Army returned its five C-75s to TWA in 1944, which 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.


    • Crew: five: two pilots, flight engineer, two cabin crew
    • Capacity: 38 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)
    • Empty weight: 30,000 lb (13,608 kg)
    • Gross weight: 45,000 lb (20,420 kg)
    • Powerplant: 4 × Wright GR-1820-G102A radial engines, 1100 hp (820 kW) each.
  • Maximum speed: 241 mph (387 km/h, 209 kn)
  • Cruise speed: 215 mph (344 km/h, 187 kn)
  • Range: 1,750 mi (2,820 km, 1,520 nmi)
  • Service ceiling: 23,300 ft (7,110 m)
  • Wing loading: 28 lb/sq ft (138 kg/m2)
  • Power/mass: 0.098 hp/lb

Ultimate encyclopedia


The B-29 was the progenitor of a series of Boeing-built bombers, transports, tankers, reconnaissance aircraft, and trainers. The re-engined B-50 Superfortress became the first aircraft to fly around the world non-stop during a 94-hour flight in 1949. The Boeing C-97 Stratofreighter airlifter, which was first flown in 1944, was followed in 1947 by its commercial airliner variant,

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