The Boeing Model 307 Stratoliner (or Strato-Clipper in Pan American service, or C-75 in USAAF service) is an American stressed-skin four-engine low-wing tailwheel monoplane airliner derived from the B-17 Flying Fortress bomber, which entered commercial service in July 1940. It was the first airliner in revenue service with a pressurized cabin, which, along with supercharged engines, allowed it to cruise above the weather. As such it represented a major advance over contemporaries, with a cruising speed of 220 mph (350 km/h) at 20,000 ft (6,100 m) compared to the Douglas DC-3's 160 mph (260 km/h), at 8,000 ft (2,400 m) then in service. When it entered commercial service it had a crew of five to six, including two pilots, a flight engineer, two flight attendants, and an optional navigator and had a capacity for 33 passengers, which later modifications increased, first to 38, and eventually to 60.
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👉 Boeing 307 Stratoliner in the context of Cabin pressure
Cabin pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft in order to create a safe and comfortable environment for humans flying at high altitudes. For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic, tanks. The air is cooled, humidified, and mixed with recirculated air by one or more environmental control systems before it is distributed to the cabin.
The first experimental pressurization systems saw use during the 1920s and 1930s. In the 1940s, the first commercial aircraft with a pressurized cabin entered service. The practice would become widespread a decade later, particularly with the introduction of the British de Havilland Comet jetliner in 1949. However, two catastrophic failures in 1954 temporarily grounded the Comet worldwide. These failures were investigated and found to be caused by a combination of progressive metal fatigue and aircraft skin stresses caused from pressurization. Improved testing involved multiple full-scale pressurization cycle tests of the entire fuselage in a water tank, and the key engineering principles learned were applied to the design of subsequent jet airliners.
Boeing 307 Stratoliner in the context of Juan Trippe
Juan Terry Trippe (June 27, 1899 – April 3, 1981) was an American commercial aviation pioneer, entrepreneur and the founder of Pan American World Airways, one of the iconic airlines of the 20th century. He was involved in the introduction of the Sikorsky S-42, which opened trans-Pacific airline travel; the Boeing 307 Stratoliner, which introduced cabin pressurization to airline operations; the Boeing 707, which started a new era in low-cost jet transportation; and the Boeing 747 jumbo jets. He also founded InterContinental Hotels & Resorts.