The Stratocruiser, Model 377, was the last of the Boeing propeller-powered luxury airliners. Known as the First Lady of the Airways, it first flew in 1947 as the elegant, civilian offspring of the C-97, a military freighter that carried soldiers and equipment during World War II. A circular stairway led from the cabin to a lower deck luxury lounge. As a sleeper, it held 28 upper- and lower-bunk units. The first Stratocruiser began service in 1949 between San Francisco to Honolulu. Only five years later, the Boeing Dash 80 prototype for the Model 707 made its first flight, and the Stratocruiser became obsolete. It found a new career as special transport for large sections of spacecraft. With its fuselage swollen by a superstructure, the once-elegant Stratocruiser became known as the Pregnant Guppy and, even larger, as the Super Guppy.