Northrop Gamma 2C (Army YA-13)
Single-engine two-seat all-metal low-wing light attack bomber monoplane

Archive Photos

Northrop Gamma 2C (Army YA-13, A.C. 34-027, c/n 5) composite photo by Skytamer.com

Northrop Gamma 2C (Army YA-13, A.C. 34-027, c/n 5) (USAF Museum photo)

Overview — Northrop Gamma Series

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 a light bomber.

Design and Development — The Northrop 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 Northrop Alphas, the fixed landing gear was covered in distinctive aerodynamic spats, and the aircraft introduced a fully enclosed cockpit.

Operational History — The Northrop 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 Nomad light attack aircraft. Military versions of the Northrop Gamma saw combat with Chinese and Spanish Republican air forces. Twenty Five Northrop Gamma 2Es were assembled in China from components provided by Northrop.

On June 2, 1933 Frank Hawks flew his Northrop Gamma 2A Texaco 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 Northrop Gamma 2G making the west-east transcontinental run in 9 hours, 26 minutes, and 10 seconds.

The most famous Northrop Gamma was the Northrop Gamma 2B Polar Star. The aircraft was carried via ship and off-loaded onto the pack ice in the Ross Sea during Lincoln Ellsworth’s 1934 expedition to Antarctica. The Northrop Gamma 2B was almost lost when the ice underneath it broke and it had to be returned to United States for repairs. The Northrop Gamma 2B 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 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. The Northrop Gamma 2B Polar Star was later recovered and donated to the Smithsonian National Air and Space Museum where it resides to this day.

Overview — Northrop Gamma 2C (Army YA-13)

During 1932, the newly formed Northrop Corporation, now affiliated with Douglas Aircraft, was in the process of building the two original Northrop Gamma models at the Los Angeles Municipal Airport (Mines Field) in Inglewood, CA. Since military contracts were, and still are crucial for the survival and development of most aircraft companies, Northrop decided to militarize the Gamma 2 as a light attack bomber for the USAAC. The Northrop Gamma 2C was finished in May 1933. The Northrop Gamma 2C became the company’s first entry into military warplane aviation. The Northrop Gamma 2C was originally powered by a 735-hp Wright Cyclone SR-1820 F-2 nine-cylinder radial engine driving a two-bladed propeller. The Northrop Gamma 2C tandem-cockpits used on previous designs were moved forward for the military design. The Northrop Gamma 2C was originally a civilian aircraft and was licensed experimentally as NX12291.

In July of 1933, the Northrop Gamma 2C was delivered to Wright Field by test pilot Carl Cover. The USAAC kept the aircraft for testing for almost a year. During this time frame, numerous Army pilots, checked out the trousered two-seater which was now referred to as an attack bomber. During the months of testing at Wright Field in Ohio, the Northrop Gamma 2C was sent Back to the Northrop factory for alteration, notably a more triangular-shaped fin and rudder, plus some internal modifications.

Due to the fact that the Northrop Gamma 2C was not yet an official United States military type, Northrop was free to offer this aircraft for export, and did. The bulk of the Northrop Gamma 2C aircraft went to China as the Northrop Gamma 2E. Meanwhile, Back at Wright Field, the Northrop Gamma 2C was stuck in the red tape of a bailment contract. Final acceptance for the USAAC’s first Northrop Gamma 2C came on 26 July 1934. The USAAC purchased the Northrop Gamma 2C, complete with a new Wright Cyclone engine, for $80,950. The Northrop Gamma 2C was given the USAAC designation YA-13 (A.C. 34-027). The Northrop YA-13 armament consisted of two .30-cal machine guns in each wing, one .30-cal machine in the rear cockpit, plus a 1,100-lb bomb load under the center section between the fixed, trousered landing-gear struts.

The USAAC was not satisfied with the large-diameter Wright Cyclone radial engine on the YA-13, and in January 1935 once more returned the aircraft to the Northrop factory. The Northrop YA-13 was subsequently re-engine with a slimmer, twin-row, 950-hp Pratt & Whitney R-1870-7 Twin Wasp radial engine, a new vertical fin, and a 3-bladed propeller. The new Northrop designation was Gamma 2F with a USAAC designation of XA-16. Ironically, further testing showed that the new XA-16 had too much power and should either have a bigger tail or a smaller engine.

Northrop Gamma Variants

Civil Variants

• Northrop Gamma 1E: Single-engine (Pratt & Whitney Hornet) two-seat closed-cabin low-wing land monoplane, 1 built, Sweden A.B Aerotransport, c/n 29.
• Northrop Gamma 2A: Single-engine (Wright Whirlwind) single-seat closed-cabin low-wing land monoplane, 1 built, Texaco Sky Chief, c/n 1.
• Northrop Gamma 2B: Single-engine (Pratt & Whitney Wasp) two-seat closed-cabin low-wing land monoplane, 1 built, Ellsworth Polar Star, c/n 2.
• Northrop Gamma 2C: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing land monoplane, 1 built, USAAC light attack aircraft YA-13, c/n 5.
• Northrop Gamma 2D: Single-engine (Wright Cyclone) single-seat closed-cabin low-wing land monoplane, 3 built, TWA cargo aircraft, c/n 8-10.
• Northrop Gamma 2E: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing land monoplane, light attack bomber, Chinese Military, c/n 14, c/n 46, c/n 48-72.
• Northrop Gamma 2EC: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing land monoplane, light attack bomber, Chinese Military, c/n 17-22, c/n 45.
• Northrop Gamma 2ED: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing land monoplane, light attack bomber, Chinese Military, c/n 15-16, c/n 23-27, c/n 30-37.
• Northrop Gamma 2ED-C: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing land monoplane, shipped to USSR, c/n 47.
• Northrop Gamma 2F: Single-engine (Pratt & Whitney R-1870-7) two-seat closed-cabin low-wing land monoplane, 1 built, USAAC light attack aircraft XA-16, c/n 5.
• Northrop Gamma 2G: Single-engine (Curtiss Conqueror) two-seat closed-cabin low-wing racing land monoplane, 1 built, Jacqueline Cochran, c/n 11.
• Northrop Gamma 2H: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing racing land monoplane, 1 built for Marron Price Guggengeim, flown by Russell W. Thaw, c/n 12.
• Northrop Gamma 2J: Single-engine (Pratt & Whitney Wasp) three-seat closed-cabin low-wing land monoplane advanced trainer, 1 prototype built, USAAC advanced trainer competition, version of Army A-17 Nomad, c/n 186
• Northrop Gamma 2L: Single-engine (delivered without engine) two-seat closed-cabin low-wing land monoplane, 1 built, sold to Bristol Aeroplane Company for Hercules engine testing, c/n 347.
• Northrop Gamma 3A: Single-engine (Pratt & Whitney Wasp) single-seat closed-cabin low-wing land monoplane fighter, 1 built, USAAC XP-948, c/n 44.
• Northrop Gamma 5A: Single-engine (Pratt & Whitney Wasp) two-seat closed-cabin low-wing land monoplane, 1 built, exported to Japanese Navy 1935, c/n 187.
• Northrop Gamma 5B: Single-engine (Pratt & Whitney Twin Wasp, Jr.) two-seat closed-cabin low-wing land monoplane, 1 built, Spanish Republican Air Force, c/n 188.
• Northrop Gamma 5D: Single-engine (Pratt & Whitney S3H-1) two-seat closed-cabin low-wing land monoplane, 1 built, exported to Japanese Navy, c/n 291.

Military Variants

• Northrop YA-13: Single-engine (Wright Cyclone) two-seat closed-cabin low-wing land monoplane, 1 built, USAAC light attack aircraft, Gamma 2C (A.C. 34-027, c/n 5).
• Northrop XA-16: Single-engine (Pratt & Whitney R-1870-7) two-seat closed-cabin low-wing land monoplane, USAAC light attack aircraft, redesigned & re-engine YA-13 (A.C. 34-027, c/n 5).
• Northrop XP-948: Single-engine (Pratt & Whitney R-1870-7) single-seat closed-cabin low-wing land monoplane, 1 built, aka Northrop 3A, USAAC pursuit adaptation of Navy XBT-1 (c/n 44).
• Northrop XFT-1: Single-engine (Wright XR-1510-8) single-seat closed-cabin low-wing land monoplane, 1 built, USN experimental fighter (BuNo 9400, c/n 6).
• Northrop XFT-2: Single-engine (Wright R-1535-72 single-seat closed-cabin low-wing land monoplane, re-designed and re-engine XFT-1, 1 converted, USN experimental fighter (BuNo 9400, c/n 6).
• Northrop A-17: Single-engine (Pratt & Whitney R-1535-11 Twin Wasp, Jr.) two-seat closed-cabin low-wing land monoplane with fixed landing gear, 109 built, USAAC light attack bomber (A.C. 35-051 to 35-160, c/n 75-184).
• Northrop A-17A: Single-engine (Pratt & Whitney Twin Wasp, Jr.) two-seat closed-cabin low-wing land monoplane with retractable gear, 129 built, USAAC light attack aircraft (A.C 36-162 to 36-261, 38-327 to 38-377).
• Northrop A-17AS: Single-engine (Pratt & Whitney R-130-41 Wasp) three-seat closed-cabin low-wing land monoplane with retractable gear, 2 built, USAAC staff transport (A.C 36-349 and A.C. 36-360, c/n 289-290).
• Northrop XBT-1: Single-engine (Pratt & Whitney R-1535-66) two-seat closed-cabin low-wing land monoplane, 1 built, USN experimental dive-bomber (BuNo 9745, c/n 43).
• Northrop BT-1: Single-engine (Pratt & Whitney R-1534-94) two-seat closed-cabin low-wing land monoplane, 54 built, USN dive-bomber (BuNo 0590 to 0626, 0628 to 0643, c/n 293 to 329, 331 to 346).

Northrop Gamma Operators

Military Operators

• China
• Japan: as BXN
• Spain: Spanish Republican Air Force - Northrop 2D and 5B Gamma
• United States: United States Army Air Corps

Civil Operators

• Manchuria: Manchukuo Manchurian Air Lines
• United States: Trans World Airlines

Specifications — Northrop Gamma 2C (Army YA-13)

• Registration: NX12291, Army A.C. 34-027
• C/n: 2
• Mfg: 5/1933
• Crew: Two (pilot and observer/rear gunner)
• Wing span: 48 ft 0 in
• Length: 29 ft 2 in
• Height: 9 ft 2 in
• Gross T/O weight: 6,500 lbs
• Maximum speed: 205 mph
• Cruising speed: 195 mph
• Range: 1,000 miles
• Service ceiling: 21,500 ft
• Powerplant: 710-hp Wright Cyclone SR-1820 F-2 #21201 radial engine
• Armament: Four forward-firing .30-cal machine guns and one flexible .30-cal machine gun for the rear gunner. Provisions for up to 1,100 lbs of bombs mounted on wing racks.
• Comments: The YA-13 was later re-engine and became the Gamma 2F (Army XA-16).

References

• Francillon, René J., McDonnell Douglas Aircraft since 1920: Volume I, Putnam Aeronautical Books, London, 1995, ISBN 0 85177 827 5, pp. 132
• Allen, Richard Sanders, The Northrop Story 1929-1939, Orion Books, New York, 1990, ISBN 0-517-56677-X, pp. 94-95.
• Aeronautical Chamber of Commerce of America, Inc., The Aircraft Year Book For 1934, Aeronautical Chamber of Commerce of America, Inc., New York, 1935, pp. 111
• National Museum of the United States Air Force, Northrop YA-13