The growth of operations on Boeing Air Transport's San Francisco-Chicago route resulted in the design and development of a purpose-designed passenger transport, the Boeing Model 80, first flown during August 1928. A large unequal-span biplane, with the lower wing of reduced chord, the Model 80 had a wing structure of wood, fabric-covered, and a fuselage and tail unit of welded steel tube, also fabric-covered. Landing gear was of fixed tailwheel type, and power was provided by three 306kW Pratt & Whitney Wasp radial engines. These were mounted in tri-motor configuration, one in the fuselage nose, and one each side of the fuselage, between the biplane wings.
The main cabin of the Model 80 accommodated 12 passengers, plus a flight stewardess. Boeing stewardesses were all registered nurses. The Model 80 provided a separate enclosed flight deck for the pilot and co-pilot/navigator. Four of these aircraft were built, entering service with Boeing Air Transport in the late summer of 1928.
The Model 80s were followed by 10 of the improved Model 80A, this type having more powerful Pratt & Whitney Hornet engines, refinements to the wing, improved streamlining and, because of the increased power available, a cabin layout to accommodate a maximum of 18 passengers.
Engines: 3 x Pratt & Whitney Wasp, 306 kW
Engines: 3 x 391kW Pratt & Whitney Hornet radial piston
Take-off weight: 7938 kg / 17500 lb
Empty weight: 4800 kg / 10582 lb
Wingspan: 24.38 m / 79 ft 12 in
Length: 17.22 m / 56 ft 6 in
Height: 4.65 m / 15 ft 3 in
Wing area: 113.34 sq.m / 1219.98 sq ft
Max. speed: 222 km/h / 138 mph
Cruise speed: 201 km/h / 125 mph
Ceiling: 4265 m / 14000 ft
Range: 740 km / 460 miles