Development and design
Boeing Air Transport was formed on February 17, 1927 by William Boeing to operate the Contract Air Mail (CAM) service between San Francisco and Chicago (CAM.18), taking over the route on July 1, 1927. The route was initially operated by single-engined Boeing 40A biplanes, which could carry four passengers, which provided a useful supplement to the subsidized revenue from carrying airmail.
In order to take better advantage of passenger traffic, Boeing decided that it needed a larger aircraft that was more suitable for passenger carrying, and in early 1928 designed a trimotor aircraft capable of carrying 12 passengers, the Model 80. Unlike the Fokker F.VII and Ford Trimotors operated by other airlines, the Model 80 was a biplane, chosen to give good takeoff and landing performance when operating from difficult airfields on its routes, many of which were at relatively high altitude. The fuselage was of fabric covered steel and aluminium tube construction, and carried its 12 passengers in three-abreast seating in a well-appointed cabin. The flight crew of two sat in an enclosed flight deck forward of the passenger cabin. The wings were of fabric covered steel and duralumin construction, with detachable wingtips to aid storage in hangars.
The first Model 80, powered by three Pratt & Whitney Wasp radial engines, flew on July 27, 1928. It was followed by three more Model 80s before production switched to the improved Model 80A, which was longer, allowing 18 passengers to be carried, and was powered by more powerful Pratt & Whitney Hornet engines, first flying on July 18, 1929, receiving its airworthiness certificate on August 20, 1929.
Operational history
The Model 80 carried out its first scheduled mail and passenger service for Boeing Air Transport on September 20, 1928, and soon proved successful. The improved Model 80A entered service in September 1929.
In May 1930, Boeing Air Transport introduced female flight attendants, hiring eight, including chief stewardess Ellen Church, all unmarried registered nurses. with the first flights carrying stewardesses beginning on May 15. The Model 80 and 80A remained in service with Boeing Air Transport (later renamed United Airlines) until replaced by the Boeing 247 twin-engined monoplane in 1934.
Variants
- Model 80 - original production version with Pratt & Whitney Wasp engines (four built)
- Model 80A - improved aerodynamics and Pratt & Whitney
Hornet engines (10 built)
- Model 80A-1 - version with revised empennage with an added finlet on each tailplane; all 10 Model 80As converted to this standard
- Model 80B-1 - single Model 80A built with open flight deck. Later modified to Model 80A-1 standard
- Model 226 - one-off Model 80A converted to executive transport for Standard Oil. Modified tail surfaces later adopted on all Model 80As (see Model 80A-1)
Operators
- United States
- Boeing Air Transport
- Monterey Peninsula Airways
- Morrison-Knudsen Company
- Robert Campbell Reeve
- Standard Oil, California
- United Airlines
Survivors
A single Model 80A-1, modified as a freighter for use in Alaska, was salvaged from a dump at Anchorage Airport in 1960, and after restoration, is displayed at the Museum of Flight at Seattle.
Specifications (Model 80A)
Data from Boeing Aircraft since 1916 [15]
General characteristics
- Crew: Three
- Capacity: 18 passengers
- Payload: 898 lb cargo (408 kg)
- Length: 56 ft 6 in (17.22 m)
- Wingspan: 80 ft 0 in (24.39 m)
- Height: 15 ft 3 in (4.65 m)
- Wing area: 1,220 sq ft (113.4 m²)
- Airfoil: Boeing N-22
- Empty weight: 10,582 lb (4,810 kg)
- Max. takeoff weight: 17,500 lb (7,940 kg)
- Powerplant: 3 × Pratt & Whitney Hornet air-cooled radials, 525 hp (392 kW) each
Performance
- Maximum speed: 138 mph (120 knots, 222 km/h)
- Cruise speed: 125 mph (109 knots, 201 km/h)
- Stall speed: 55 mph(48 knots, 89 km/h)
- Range: 460 mi (400 nm, 741 km)
- Service ceiling: 14,000 ft (4,270 m)
- Rate of climb: 900 ft/min (4.6 m/s)