Northrop Gamma
A single-engined, all-metal, low-wing monoplane built by the Northrop Corporation in the 1930s and developed from the Northrop Alpha. About sixty were built, most of them one-off variants made for individual customers: mailplanes for Trans World Airlines, Frank Hawks's record-breaking Sky Chief, and Lincoln Ellsworth's Polar Star, which made the first trans-Antarctic flight in 1935. Howard Hughes set a transcontinental record in a borrowed Gamma in January 1936. Military versions fought with Chinese and Spanish Republican forces, and the design's military development became the Northrop A-17 attack aircraft. The Polar Star survives in the Smithsonian's collection.
Why It Mattered
The Gamma was one of the first designs built by the newly established Northrop Corporation, and the Smithsonian counts Frank Hawks's Sky Chief and Lincoln Ellsworth's Polar Star as the first two the company produced, in 1933. History of War describes it as a low-wing monoplane designed for special-purpose and mail-carrying work, and it filled those briefs less as a routine carrier than as a flying laboratory and record-breaker. Hawks flew his Gamma nonstop from Los Angeles to New York in 13 hours, 26 minutes and 15 seconds on 2 June 1933, and in January 1936 Howard Hughes, flying a Gamma borrowed from Jacqueline Cochran, cut the crossing to 9 hours, 26 minutes and 10 seconds. Its most lasting legacy was military: developed further, the Gamma became the Northrop A-17, the U.S. Army Air Corps' standard attack aircraft of the late 1930s.
Design Notes
The Gamma developed the earlier Northrop Alpha, keeping its wing fillets and its multicellular stressed-skin wing construction. The airframe was all-metal and low-winged, the fixed undercarriage wore large aerodynamic spats, and the type introduced a fully enclosed cockpit to the line. There was no standard Gamma: each variant was built to a customer's order, differing in engine, seating and purpose. Ellsworth's Polar Star had two seats in tandem with dual controls; TWA's three Gamma 2D freighters had a 710 hp Wright Cyclone; the 2G was a two-seat racing version, first built around a Curtiss Conqueror engine. Several Gammas were flying laboratories: one 2D was rebuilt as an "Experimental Overweather Laboratory" for high-altitude research into icing, superchargers, radios and turbulence, and later flown by the Army as the UC-100; the 2H tested the Sperry automatic pilot, and the single 2L went to Bristol for Hercules engine testing.
Operational History
Civil work was limited: the Gamma saw fairly brief service as a mailplane with Trans World Airlines, and most aircraft worked for individual owners on special projects. The pattern was set by the first two aircraft of 1933: Hawks's single-seat Sky Chief, sold to Texaco, and Ellsworth's two-seat Polar Star. Ellsworth took the Polar Star to Antarctica in 1934, but the season was lost when the sea ice broke under its skis, and a second attempt that September ended with the aircraft sent to Chile for repairs to a broken connecting rod. On 3 January 1935 Ellsworth and Bernt Balchen made a first flight over Graham Land, and that November Ellsworth returned with pilot Herbert Hollick-Kenyon for the crossing itself. They took off from Dundee Island on 23 November 1935, made four landings on the way, crossed the Eternity Range as the first men to visit western Antarctica, and were forced down by fuel exhaustion on 5 December, 25 miles short of Little America, walking the rest of the way in six days. Military versions saw combat with the Chinese and Spanish Republican air forces: twenty-five Gamma 2Es assembled in China from Northrop components flew attack missions in the early stages of the war with Japan, and a retired TWA aircraft flew coastal patrol for Republican Spain. The U.S. Army's interest took a different path: a privately built Gamma was submitted for Army tests in July 1933, the Gamma 2F began its Army tests on 6 October 1934, and on 24 December 1934 the Army ordered 110 Gamma 2Fs under the designation A-17. Only one Gamma 2J trainer was built, intended for the Army Air Corps; the North American BC-1 was preferred.
Afterlife
Wikipedia puts total production at 60 aircraft, and most variants were built in ones and twos: three 2D freighters were the largest civil batch, and several versions were single examples. The type's survival rests on its most famous airframe: Hollick-Kenyon went back to recover the Polar Star after the crossing, and Ellsworth donated it to the Smithsonian in April 1936. It remains in the National Air and Space Museum's collection today, currently not on display, either on loan or in storage. Its design lived on in the A-17 line: renamed the Nomad in British and Commonwealth service, the Gamma's attack descendant spent the war in the flying schools of Canada and South Africa.