Northrop Gamma

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Northrop Gamma was a single-engine all-metal monoplane cargo aircraft used in the 1930s. Towards the end of its service life, it was developed into a light bomber.

1 Development
2 Operational history
3 Variants
4 Users
5 Specifications (Gamma 2D)
6 References
7 Related content

[edit] Development

The Gamma was a further development of the successful Northrop Alpha and shared its predecessor's aerodynamic innovations with wing fillets and multicellular stressed-skin wing construction. Like late Alphas, the fixed landing gear was covered in distinctive aerodynamic spats, and the aircraft introduced a fully enclosed cockpit.

[edit] Operational history

The Gamma saw fairly limited civilian service as mail planes with Trans World Airlines but had an illustrious career as flying laboratory and record-breaking aircraft. The US military found the design sufficiently interesting to encourage Northrop to develop it into what eventually became the Northrop A-17 light attack aircraft. Military versions of the Gamma saw combat with Chinese and Spanish Republican air forces.

On 2 June 1933 Frank Hawks flew his Gamma 2A "Sky Chief" from Los Angeles to New York in a record 13 hours, 26 minutes, and 15 seconds. In 1935, Howard Hughes improved on this time in his modified Gamma 2G making the west-east transcontinental run in 9 hours, 26 minutes, and 10 seconds.

The most famous Gamma was the "Polar Star." The aircraft was carried aboard the ship during Lincoln Ellsworth's 1934 expedition to Antarctica. However, the airplane was almost lost when the ice underneath it broke and it had to be returned to United States for repairs. Polar Star's second return to Antarctica in September 1934 was also futile -- a connecting rod broke and the aircraft had to be returned yet again for repairs. On 3 January 1935, Ellsworth and pilot Bernt Balchen finally became the first people to fly over Antarctica. On 23 November 1935, Ellsworth and Canadian pilot Herbert Hollick-Kenyon attempted the world's first trans-Antarctic flight from Dundee Island in the Weddell Sea to Little America. The crew made four stops during their journey, in the process becoming the first people ever to visit Western Antarctica. During one stop, a blizzard completely packed the fuselage with snow which took a day to clear out. On 5 December after traveling over 2,400 miles (3,865 km) the aircraft ran out of fuel just 25 miles (40 km) short of the goal. The intrepid crew took 6 days to travel the remainder of the journey and stayed in the abandoned Richard E. Byrd camp until being found by the Discovery II research vessel on 15 January 1936. Polar Star was later recovered and donated to the Smithsonian National Air and Space Museum where it resides to this day.

[edit] Variants

Gamma 2A - first production aircraft, sold to Texaco and flown by Frank Hawks as "Sky Chief"
Gamma 2B - two-seat version with tandem controls, flown across Antarctica as the "Polar Star"
Gamma 2C (YA-13) - Northrop-proposed attack version to compete with Curtiss A-12 Shrike armed with 4x 0.30 cal machine guns in the wings, 1x 0.30 cal machine gun on a flexible mount for rear defence, and up to 1,100 lb (500 kg) of bombs under the wings, evaluated by USAAC in 1933
YA-16 - YA-13 prototype redesignated after being fitted with a Pratt & Whitney R-1830-9 engine
Gamma 2D - cargo version used by TWA, three built. One aircraft was converted into an "Experimental Overweather Laboratory" studying icing, superchargers, radios, and turbulence at 20,000-35,000 ft (6,100-10,670 m), then used by USAAC under the designation UC-100. Another retired TWA aircraft was used by Spanish Republican air force for coastal patrol.
Gamma 2E - similar to Gamma 2C in armament except for a 1,600 lb (727 kg) bomb load, used by Chinese air force as a light bomber until 1938 with a number of aircraft built in China, one used by the British Aeroplane & Armament Experimental Establishment
Gamma 2F - another attack version developed in parallel with Gamma 2C, entered service as Northrop A-17 Nomad
Gamma 2G - two-seat race version, originally with a Curtiss Conqueror engine, later changed to Pratt & Whitney Twin Wasp Jr., then to Wright Cyclone SGR-1820-G-5. Flown by Jacqueline Cochran and Howard Hughes
Gamma 2H - testbed for Sperry automatic pilot, also flown by Russell Thaw to a third-place finish in the 1935 Bendix Trophy race
Gamma 2L - used by Bristol for Bristol Hercules engine testing
Gamma 5A - one aircraft exported to Japanese Navy (designation BXN1) as a study in modern engineering
Gamma 5B - two-seat version with the cockpits moved forward, used by the Spanish Republican air force for coastal patrol
Gamma 5D - one aircraft exported to Japan with "Army-type" equipment (designation BXN2), studied by Nakajima, then passed to Manchurian Air Lines which used it for aerial reconnaissance over China and USSR.

[edit] Users

Trans World Airlines, Manchurian Air Lines, armed forces of United States, Republican Spain, China, Japan.

[edit] Specifications (Gamma 2D)

General characteristics

Crew: 1
Length: 31 ft 2 in (9.5 m)
Wingspan: 47 ft 10 in (14.6 m)
Height: ()
Wing area: 363 ft² (33.7 m²)
Empty weight: 4,120 lb (1,870 kg)
Loaded weight: 7,350 lb (3,330 kg)
Max takeoff weight: lb (kg)
Powerplant: 1× Wright Cyclone , 710 hp (530 kW)

Performance

Maximum speed: 224 mph (360 km/h)
Range: 1,650 mi (2,655 km)
Service ceiling: 23,000 ft (7,000 m)
Wing loading: 20.2 lb/ft² (99.1 kg/m²)
Power/mass: 0.10 hp/lb (0.16 kW/kg)

[edit] References

Smith, MJ, Jr. (1986) Passenger airliners of the United States, 1926-1991. Pictorial Histories Publishing Company. ISBN 0-933126-72-7
The story of the "Polar Star" at the Smithsonian