Northrop A-17

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The Northrop A-17 was the standard US Army Air Corps attack aircraft during the second half of the 1930s. It was based on the Northrop Gamma, a low-winged monoplane designed as a special purpose and mail-carrying aircraft. One privately built Gamma had been submitted to the Army for tests in July 1933. This aircraft was returned to Northrop early in 1934 for modifications, becoming the XA-13 in June 1934.

The XA-13 was followed by the Gamma 2F, which would become the prototype for the production A-17. One problem with the XA-13 had been the large diameter of its Wright radial engines, which had restricted the pilot’s view. The Gamma 2F used a 750hp Pratt & Whitney R-1535-11 fourteen-cylinder radial engine, which had a smaller diameter than the Wright engine of the XA-13, and than the Pratt & Whitney R-1830-7 installed in the XA-16.

The Gamma 2F also had a longer, narrower canopy than the XA-13, with the radio-operator/ rear gunner moved further back. The fuselage was better streamlined, and the fixed undercarriage of the XA-13 was replaced by a semi-retractable unit, with the wheels folding back into large fairings on the underside of the aircraft.

The Gamma 2F began Army tests on 6 October 1934. Although it was returned to Northrop for modifications, on 24 December 1934 the Army placed a contract for 110 Gamma 2Fs, with the designation A-17.

A-17

The Gamma 2F was returned to the Army Air Corps on 27 July 1935, after all of the changes requested had been made. Amongst them was the replacement of the semi-retractable undercarriage with a fixed version and increased streamlining. The canopy was also modified, and the original all-glass version was replaced by one with an unglazed central section between the two sliding canopies. The A-17 was armed with one rear-firing .30in machine gun and four wing-mounted guns, and could carry 1,200lb of bombs. The 109 production aircraft needed further changes, amongst them the installation of dive-breaks. Delivery of the first production aircraft was thus delayed to 23 December 1935, and the last aircraft was not completed until 5 January 1937.

A-17A

Although the semi-retractable landing gear of the Gamma 2F had not been a success, Northrop had had more luck with the version used on their Gamma 2J advanced trainer, and suggesting fitting this to the A-17. Attracted by the improved performance offered by the entirely enclosed wheels, the Army placed an order for 100 A-17As. The new model made its maiden flight on 16 July 1936, but development and production problems meant that deliveries did not take place until April-December 1937. Another twenty-nine aircraft were ordered during 1937, which were delivered in June-September 1938. The A-17A was powered by one 825hp R-1535-13 engine, which partly made up for the increased weight of the landing gear. Like the A-17 it was armed with five machine guns, and had a standard bomb load of either four 100lb bombs on bomb racks, or twenty 30lb bombs in the bomb bay, which could be increased to 1,200lb at the cost of range.

Service Career

The A-17 entered service with the 3rd Attack Group in February 1936. Compared to the Curtiss A-12 Shrike it was faster, could fly higher, had longer range and could carry more bombs, and it was received with some enthusiasm. The A-17 also equipped the 17th Attack Group at March Field, California, the 38th Attack Squadron at Langley Field, Virginia and the 74th Attack Squadron in Panama.

During 1937 the A-17s were phased out in favour of the A-17A, and were allocated to training units. The A-17A had a slightly longer service career. It was still the Air Corps’s standard attack aircraft in September 1939, although by then both of the Attack Groups had also been given a number of B-18s, and were on the verge of becoming Light Bombardment Groups, while the twin-engined A-20 Havoc was close to entering service. On 20 June 1940 the A-17A was declared surplus to requirements, and 93 were returned to Douglas. This was done to allow the company to sell the A-17As to France, but events overtook that plan. The French order was then taken over by the British. In British and Canadian service the aircraft was known as the Northrop Nomad, and was used in the flying schools of South Africa and Canada.

 

A-17

A-17A

Engine

Pratt & Whitney R-1535-11

R-1535-13

Power

750hp

825hp

Span

47ft 8 1/2in

47ft 9in

Length

31ft 8 5/8in

31ft 8in

Height

11ft 10 1/2in

12ft

Empty Weight

4,764lb

5,106lb

Gross Weight

7,336lb

7,550lb

Maximum Speed

206mph at sea level

220mph at 2,500ft

Cruising Speed

170mph

170mph

Climb rate

1,530ft/min

1,350ft/min

Ceiling

20,700ft

19,400ft

Range (normal)

650 miles

730 miles

Guns

Five 0.30in machine guns

Bomb load

1,200lb

Suggested Reading
McDonnell Douglas: v.1, Rene J. Francillon (Amazon.co.uk)
McDonnell Douglas: v.1, Rene J. Francillon (Amazon.com)

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How to cite this article: Rickard, J (6 October 2008), Northrop A-17 , http://www.historyofwar.org/articles/weapons_Northrop_A-17.html

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