The 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 the
A-17 light bomber.
Design and 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.
Operational history
The Gamma saw fairly limited civilian service as mail planes with
Trans World Airlines but had an illustrious career as a 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.[1] Twenty Five Gamma 2Es were assembled in
China from components provided by Northrop; these were deployed in various attack missions during the early stages of the
Second Sino-Japanese War, particular against Imperial Japanese naval assets.[2][3] In the morning of 11 November 1937, three Chinese Air Force Northrop 2ECs of the
2nd BG, 14th Squadron led by Capt. Yu attacked the
IJNfleet aircraft carrierKaga off the Ma'anshan Islands; the bombs fell wide into Kaga's wake, and the Chinese Gammas were pursued and intercepted by three
A5Ms of Kaga's
combat air patrol led by flight leader
Jirō Chōno, shooting down two (Gammas no. 1405 of Sung I-Ching and Li Xi-Yong, and no. 1402 of Peng Te-Ming and Li Huan-Chieh) while Yu managed to escape into the clouds and return his damaged Gamma to base.[4]
On June 2, 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.[1]
The most famous Gamma was the Polar Star. The aircraft was carried via ship and offloaded onto the pack ice in the
Ross Sea during
Lincoln Ellsworth's 1934 expedition to
Antarctica. The Gamma was almost lost when the ice underneath it broke, and had to be returned to the United States for repairs. Polar Star's second assignment to Antarctica in September 1934 was also futile — a connecting rod broke and the aircraft had to be returned yet again for repairs. On January 3, 1935, Ellsworth and pilot
Bernt Balchen finally flew over Antarctica.
On November 23, 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 December 5, 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 six 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 January 15, 1936. Polar Star was later recovered and donated to the
SmithsonianNational Air and Space Museum.[5]
Variants
Gamma 2A
First production aircraft, sold to Texaco and flown by
Frank Hawks as "Sky Chief", 785 hp (585 kW) Wright radial engine.[2][6]
Gamma 2B
Two-seat version with tandem controls, flown across Antarctica as the Polar Star, 500 hp (373 kW) Pratt & Whitney Wasp radial engine.[2]
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
Cargo version used by TWA, three built, 710 hp (529 kW) Wright Cyclone engine.[2] 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.
Two-seat trainer powered by 600 hp (448 kW) Pratt & Whitney Wasp with retractable undercarriage intended for USAAC.
North American BC-1 preferred. Only one built.[8]
One aircraft exported to
Imperial 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
Manchukuo National Airways which used it for aerial reconnaissance over China and USSR.
^"Martyr Chen Xi-chun". air.mnd.gov.tw. Retrieved 2020-11-20. On 19 August 1937, the 11th Bomber Squadron Cmdr. Gong Yin-cheng and 9th BS Cmdr. Xie Yu-ching from the 2nd BG, each led 14 Northrop Gamma 2Es (7 each) to depart from Guangde at 0900 hours and 0940 hours respectively en route to Yushan at the mouth of the Yantze River to bomb hostile carriers and vessels at Bai'long Harbor...
^Gustavsson, Hakans.
"Japanese biplane fighter aces - Hatsu-o Hidaka". Biplane Fighter Aces - Japan. Retrieved 2020-11-20. On 11 November 1937, three Northrop 2ECs (Gammas) of the 2nd BG led by Yu C. Y. attacked the carrier Kaga off the Ma'anshan Islands, missing the carrier, they were intercepted by three A5Ms from Kaga. Two of them were shot down; one was claimed by PO3c Hidaka while the second was claimed by the shotai leader Jiro Chono (his first combat and first victory).
Eden, Paul and Soph Moeng. The Complete Encyclopedia of World Aircraft. London: Amber Books Ltd., 2002.
ISBN0-7607-3432-1.
Francillon, René J. McDonnell Douglas Aircraft since 1920. London:Putnam, 1979.
ISBN0-370-00050-1.
Smith, M.J. Jr. Passenger Airliners of the United States, 1926–1991. Missoula, Montana: Pictorial Histories Publishing Company, 1986.
ISBN0-933126-72-7.
1 X as second letter is for experimental aircraft or imported technology demonstrators not intended for service,
2 Hyphenated trailing letter (-J, -K, -L, -N or -S) denotes design modified for secondary role, 3 Possibly incorrect designation, but used in many sources