Northrop Gamma 2ED
Single-engine two-seat low-wing bomber monoplane

Archive Photos

Northrop Gamma 2E (Northrop photo via John Shupek Collection)

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 2E Series

The Northrop Gamma 2E/2EC/2EDs were two-place military attack bombers supplied on the order of the Chinese government during the 1934-1935 timeframe. Powered by Wright Cyclone R-1820-F53, 750-hp engines, they were armed with two .30-cal machine guns in the wings, and carried a 1,100-lb bomb load. A semi-retractable bomb-aiming panel and gun port was located under the rear cockpit. The first delivery was 19 February 1934. Two Northrop Gamma 2E’s (c/n 14 and c/n 46) were sold, and the parts for an additional twenty-five aircraft (c/n 48 through c/n 72) were crated and shipped to China. Upon arrival, they were assembled at the plant of the Central Aircraft Manufacturing Company (CAMCO). The aircraft were used by the Chinese Air Force during hostilities with Japan from 1934-1938.

One Northrop Gamma 2ED-C (c/n 13, K5053) was sold to the British Air Ministry in November 1934 and another Northrop Gamma 2EC (c/n 47, NC13760) was sold to the USSR.

Fifteen Northrop Gamma 2Es (c/n 15, 16, 23-27 and 30-37) also went to the Chinese government in 1934, as did seventeen 17 Northrop Gamma 2ECs (c/n 17-22 and 45). The Northrop Gamma 2EC and Northrop Gamma 2ED models differed from the basic Northrop Gamma 2Es in seating, tailplane configuration, and the use of three-bladed propellers.

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

Northrop Gamma 2E Specifications and Performance Data

Type

• Two-seat bomber monoplane

Wings

• Low-wing cantilever monoplane.
• Center-section of parallel chord and thickness built into the fuselage.
• Outer sections of tapering chord and thickness.
• All-metal construction, with stressed-skin reinforced with U-section stringers, running parallel to the span and riveted to cellular framework.
• Outer sections attached to center-sections by bolts through vertical flanges of angles riveted to outer ends of center-section and roots of outer sections with diaphragms forming solid ribs between.
• Frise-type fabric-covered ailerons.
• Schenk, hydraulically-operated split flaps from ailerons to roots of outer sections.

Fuselage

• Stress-skin structure, with smooth sheet covering in longitudinal panels riveted to open-section transverse rings.
• Skin stiffened by rolling inwards one edge of each covering panel.

Tail Unit

• Monoplane type.
• Cantilever tail-plane and fin.
• Metal stressed-skin structure.
• Horn-balanced rudder.
• Mass-balanced elevators.
• Trimming-tabs and elevators and rudder.

Undercarriage

• Divided type.
• Each unit consists of a wheel carried between two cantilever oleo shock-absorber legs, the whole enclosed in streamlined trousers faired into the center-section roots.
• Bendix wheel-brakes.
• Swivelling tail-wheel.

Power Plant

• One Wright Cyclone SR-1820-F53 nine-cylinder radial air-cooled engine, developing 750-hp at 11,000 feet (3,350 m).
• NACA cowling.
• Hamilton-Standard control-pitch airscrew.
• Fuel tanks in center-section.
• Total capacity 362 U.S. Gallons (302 Imperial gallons = 1,406 liters).
• Oil tank (22 US gallons) in engine compartment athwart the fuselage.

Accommodation

• Tandem cockpits, with dual controls.
• Canopy over cockpits has sliding sections and the after portion is hinged for operation of movable rear gun.
• Armament consists of three .30-caliber guns, two mounted in the wings and firing forward outside the airscrew disc and one on a movable mounting in the Back cockpit.
• External bomb-racks for a total load of 1,100 lbs (500 kg), below center-section.
• Retractable bomb-sighting position in floor of observers cockpit.

Dimensions

• Wingspan: 48 feet 0 inches (14.64 m)
• Length: 28 feet 10 inches (8.8 m)
• Height: 9 feet 1 inch (2.75 m)
• Wing area: 363 ft² (33.7 m²)

Weights and Loadings

• Weight empty: 3,850 lbs (1,745 kg)
• Fuel and oil: 1,905 lbs (864 kg)
• Wireless: 106 lbs (48 kg)
• Armament and ammunition: 195 lbs (80 kg)
• Crew: 400 lbs (181 kg)
• Bombs: 1,100 lbs (500 kg)
• Flares: 40 lbs (18 kg)
• Total disposable load: 3,750 lbs (1,700 kg)
• Weight loaded: 7,600 lbs (3445 kg)
• Wing loading: 20.9 lbs/ft² (102 kg/m²)
• Power loading (full load at 11,000 ft = 3,350 m): 10.1 lbs/hp (4.5 kg/hp)

Performance (Maximum loading with 1,000 lbs = 450 kg bombs)

• Maximum speed at sea level: 183 mph (295 km/h)
• Maximum speed at 11,000 ft (3,500 m): 210 mph (303 km/h)
• Rate of climb at sea level: 930 ft/min (282 m/min)
• Maximum rate of climb at 11,500 ft (3,500 m): 1,060 ft/min (324 m/min)
• Climb to 5,000 ft (1,525 m): 5 minutes
• Climb to 10,000 ft (3,050 m): 10 minutes
• Service ceiling: 23,600 ft (7,190 m)

Performance (a loaded weight of 6,400 lbs = 2,000 kg without bombs and racks)

• Maximum speed at sea level: 199 mph (320 km/h)
• Maximum speed at 11,500 feet (3,500 m): 228 mph (367 km/h)
• Rate of climb at sea level: 1175 ft/min (360 m/m)
• Maximum rate of climb at 11,500 ft (3,050 m): 1,360 ft/min (816 m/min)
• Climb to 5,000 ft (1,525 m): 4 minutes
• Climb to 10,000 ft (3,050 m): 7 minutes
• Service ceiling: 29,300 ft (8,930 m)
• Absolute ceiling: 30,700 ft (9,360 m)

References

• Wikipedia: Northrop Gamma
• Allen, Richard Sanders, The Northrop Story 1929-1939, Orion Books, New York, 1990, ISBN 0-517-56677-X, pp. 138, 150-155.
• Grey, C.G. and Bridgeman, Leonard. Jane’s All The World’s Aircraft 1936, Sampson Low, Marston & Company, Ltd., London, 1936, pp. 299c-300c
• Photo, Northrop Gamma 2E, Skytamer Archive