Boeing 307 Stratoliner (C-75)

History

The World War II-era B-17 Flying Fortress inspired Boeing to build a similar long-range four-engine civilian commercial airliner based on the successful components of the classic fighter. Work took place in the mid-1930s and the company name was "Type 307" to cover the design.

The Type 307 featured an entirely new airframe, while retaining the main wing aircraft (along with its matching engines) and empennage of the soon-to-be-famous WWII bombers (specifically the production B-17C).

In 1937, Pan Am became the launch customer with an order of two aircraft, followed by competitor TWA with an order of five. Pan Am then ordered four more aircraft, bringing the total committed order to eleven.

The USAF took at least 5 TWA Type 307s in stock and modified them by adding internal fuel tanks and bunks, removing pressurization equipment and some passenger seats. The landing gear was reinforced for the rigors of military service, and this form of aircraft received the "C-75" designation to reflect its cargo/transport role.

Deliveries of these aircraft began in 1942, and the fleet remained in service until mid-1944. Back in November 1942, the military introduced a new military four-engine transport aircraft with transatlantic capability, the C-54 "Skymaster," which then began to take over the active C-75's, according to Douglas Aircraft.

Duties. All C-75 flights operate on routes covering the Atlantic (the aircraft was not shown in the Pacific theater).

When the war in Europe ended in April-May 1945, the USAF returned five of its C-75 transports to TWA. These were changed back to their original form of civilian passenger transport by Boeing, ending their days.

Variants in the 307 model series include the 307B model, which increases the operator's crew to seven and, perhaps more importantly, switches to a Wright Cyclone GR-1820-G105A series engine that supports two-stage turbochargers, Assisted flight improves high altitude. The Type 307B-1 was a postwar model that received the wing main aircraft and updated electronics of the B-17G production bomber.

This variant is powered by a Wright Cyclone GR-1820-G606 series air-cooled radial engine.

In addition to wartime service, the Type 307 was used by a number of foreign operators (all civilian) including Cambodia, Ecuador, France and Laos. The model was briefly used by the Haitian Air Force, and after decades of service, the line was completely phased out in 1975.

Specification

Basic

Production

Roles

Dimensions

Weight

Performance

Performance

Armor

Changes