Boeing 307 Stratoliner

About

Development History

Although Boeing had suffered a setback because of Douglas's unprecedented success with the DC-2 and DC-3 family of true airliners, it did not take long to rebound. Even as the DC-3 was starting a new era, by introducing unit operating costs low enough for an airline to make a profit, the Boeing 307 was developed to start another era, that of pressurized comfort at higher altitudes than had hitherto been contemplated.

The aircraft was the result of considerable research in high altitude flying by "Tommy" Tomlinson, of T.W.A., who was estimated to have flown more hours above 30,000 feet than all other pilots combined. Resulting from his recommendations, Boeing produced an airliner which could cruise at 14,000 feet, or, as the neatly descriptive phrase went at the time, "above the weather." The Model 307, or Stratoliner, was a straightforward conversion from the supremely successful B-17 Flying Fortress bomber, with a 33-seat commercial fuselage substituted for the bomber's. The most important technical feature was that the entire cabin was pressurized so that the use of special oxygen equipment was unnecessary. Pressure differential was 2 1/2 lb/sq. in. Another aspect of the stringent specifications was that high octane fuel was being developed to obtain higher supercharger pressure to maintain engine power at high altitudes.

Airline Service

The Boeing 307 first flew on 31 December 1938 and T.W.A. put it into service on the transcontinental route on 8 July 1940, reducing the time to 13 hr 40 min, and cutting two hours off the DC-3's. Unfortunately, its career was short-lived as on 24 December 1941 the fleet was withdrawn from civil work and transferred to trans-Atlantic wartime duties. Only nine were built and Pan American was the only other customer. Each one cost $315,000 in 1937 when ordered. Most of them survived the war and performed good service for the French airline Aigle Azur, operating to French Indo-China. Here they became involved with the Vietnam War, worked with operators such as Air Laos, and paid their dues. One example survives, and awaits the time when the National Air and Space Museum of the Smithsonian Institution can build a structure big enough for it.