Northrop A-17

Northrop A-17 or Northrop Gamma 2F was an advanced version of the Northrop Gamma (en). This aircraft ground attack single-engine two-seater, was built in 1935 by the Northrop Corporation on behalf of the U.S. Army Air Corps.

Design & Development

A-17

Northrop Gamma 2F was the version for the ground attack, the air transport Northrop Gamma. Developed in parallel with the program Northrop Gamma 2C, which gave birth to the IS-13 and XA-16, Gamma 2F had a drift, a cockpit and parts redesigned from the Gamma 2C plus a new set of semi landing Retracting and a bomb bay can hold 20 bombs of 13.6 kg. The prototype was delivered for testing to the USAAC, October 6, 1934.

Although the evaluation was largely positive, the U.S. Army requested that some changes be made ​​especially in aerodynamics. 2F returned to the plant to undergo adjustments requested. As the new landing gear had brought a slight improvement in performance, it was replaced by a conventional fixed but streamlined train. In addition, all lines of the aircraft (fuselage and drift) were softened for better aerodynamics, the canopy was, too, reworked with the addition of a non-glass between the driver and the gunner part.

December 24, 1934, the USAAC announced its intention to acquire 110 Gamma 2F, under the official designation Northrop A-17.

Although the A-17 was a good performance and was well armed, its main commercial appeal was its very competitive price of 19 $ 000 room (without military equipment). Which was very attractive at a time when America was fighting against the Great Depression. The contract was officially signed on 1 March 1935, it was the largest pre-war army and a real boon for the new branch of Northrop contract.

At first it was planned to install larger engines like Cyclone R-1820 or R-1830-7 Wasp for production models, as it was decided on the Northrop YA-13. However, the IS-13 proved surmotorisé with the R-1830-7, and more to prevent a supply disruption, it was decided to equip the A-17 production with the small R-1535.

As amended following the expectations of the USAAC, the first Gamma 2F form was delivered July 27, 1935, under the official name A-17 (Order No. 35-51 series). The other 109 A-17 (35-52 to 35-160) were delivered between December 1935 and January 1937. They were equipped with the engine R-1535-11 750 hp. They differed from the prototype is equipped with 3 segments perforated by wing spoilers. In addition, the firing system ventral backward, present on the prototype was taken on the production model.

A-17A

Northrop developed a variant, A-17A, with a new set of fully retractable landing this time. The retractable landing gear was examined for the first time on the Gamma 2J, a training aircraft prototype. The design of the A-17 proved to be easily adaptable to a retractable landing gear, with relatively few changes required. However, the use of this equipment required the wing roots are enlarged to provide space to accommodate the wheels.

The A-17A was equipped with a motor R-1535-13 Twin Wasp Junior 825 hp. His offensive and defensive armament was the same as the A-17, that is to say, five.30-caliber machine guns (7.62 mm) and 544 kg of bombs in total (20 cluster bombs 13 6 kg in the hold and four 45 kg bombs under the wings).

On 29 January 1936 the USAAC placed an order for 100 aircraft (Numbers 36-162 to 36-261 series). The first production A-17A (36-162) flew for the first time on 16 July 1936. The A-17A experienced some teething problems, including the landing gear, which delayed the delivery of other devices until February 4, 1937. During this time, the plane was used for testing. Two accidents caused by defects in the landing gear led to a further delay for the second generation devices until April 1937. Once these problems are fixed, the 100 A-17A was delivered to the USAAC between April and December 1937.

A new order of 29 additional devices (38-327 to 38-355) was passed in the second half of 1937, which was fought between June and September 1938.

A-17AS

Northrop A-17AS was disarmed three seater version of A-17A, for transporting people. The “S” of the official designation implies “Staff” or “Special”. Two copies were ordered March 20, 1936. Although their numbers 289 and 290 series manufacturer follow the nomenclature of the first delivery of A-17A, they were built and delivered before.

The first A-17AS (36-349) was powered by a Pratt & Whitney R-1340 -41 9 air-cooled 600-hp powered a three-bladed cylinders. It was delivered July 17, 1936. He served as personal transport aircraft Maj. Gen. Oscar Westover. General Westover was the chief of the Army Air Corps, and he personally flew for nearly two years this aircraft for flights inspections or monitoring operation. September 21, 1938, the plane crashed in Burbank (California), killing General Westover and his mechanic S / Sgt Sameul Hymes.

The second A-17AS (36-350) was assigned to transport Brigadier General Henry H. Arnold. Brigadier General Westover succeeded to his death. And General Arnold was appointed as his replacement as head of the Air Corp and retained this function throughout the Second World War. The second was equipped with a radial engine R-1340-45 600 hp operating a two-bladed propeller. The 36-350 was lost in an accident March 2, 1940, but General Arnold was not on board that day.

Operational service

A-17

The first production unit A-17 (35-52) was sent to Wright Field in December 1935, after having been initially evaluated by the Technical Training Command at Chanute Field (Illinois). In early February 1936, the A-17 entered service in the 3rd Attack Group (to equip the 8th, 13th and 90th Squadrons) based at Barksdale Field Louisiana. But they also fitted out the 17th Attack Group (34th, 37th, and 95th Squadrons) based at March Field (California), who had recently been fitted with Boeing P-26 Peashooter.

The same year, the A-17 present in both groups were supplemented by USAAC version A-17A with retractable undercarriage. Shortly after, the A-17 were withdrawn from active service and transferred to training units. At the time of the attack on Pearl Harbor, the A-17 was completely obsolete, and the survivors ended their careers either as birddog training is the Aircraft mechanics’ school of Roosevelt Field (New York).

The last A-17 was retired from active service in the USAAF in 1944.

Note that the A-17 series number 35-122, was used by the National Advisory Committee for Aeronautics (NACA) for tests on wings laminar structure. New highly polished surfaces on and around the existing wing structure, surpassing the edges of attacks and leaks to double the thickness of the wing. A two-bladed propeller driven by a small auxiliary engine was mounted on the new leading edge of each wing to increase the speed of the airflow over the extrados. However, it was found that it was easier to get the same data using conventional blowers. NACA therefore abandoned the project.

The Republic of China was commissioned consisting of 45 aircraft Northrop Gamma 2E and A-17, as well as two C-19 Alpha. Gamma 2E and A-17 were used very intensively during the attacks of Japanese supply lines port Shanghai by the 1st and 2nd Groups, before being removed from active service.

A-17A (USAAC) / Nomad (RAF)

The A-17As was placed on active service in 1937 in the 3rd Attack Group (8th, 13th, and 90th Squadrons) at Barksdale Field (Louisiana) and the 17th Attack Group (34th, 37th, and 95th Squadrons) based March Field (California).

It gradually replaced the A-17 fixed train used in these units. The A-17A was relatively fast and had a pretty awesome weapon for this period and the years from 1938 to 1939, he was declared as attack aircraft ever built most effective ground.

However, the U.S. Army decided that the twin-engine aircraft had a greater advantage for this type of mission, compared to single-engine aircraft and the life expectancy of the A-17A active duty immediately declined. After a brief service of three years in the USAAC, the A-17A was put in surplus. Some remained in service for training missions but the last American A-17A was finally put to waste 31 October 1944.

Just after the start of the Second World War, with the invasion of Poland by the Nazis, the French air force was an urgent need to dive bombers. And as the U.S. Army considered the A-17A as obsolete, a French buying commission which was the United States requested permission to acquire 93 A-17A surplus of USAAC.

The 93 A-17A ordered by France were returned to the factory Northrop (which was known at that time as the Douglas El Segundo division), where they were rearmed and re-engined with an engine Pratt & Whitney Twin Wasp JrS2A5-G 825 hp. Unfortunately, by the time the aircraft are delivered, France had fallen. The contract then went to the British buying commission, which at the time was willing to buy anything that had wings. British A-17A entered service with the RAF, under the official name of Northrop Nomad and serial numbers: AS440/AS462, AS958/AS976 and AW420/AW438.

The rest of the French control 32 devices were transferred to Canada, where they were used as aircraft of advanced training.

However, the RAF found that the Nomad was obsolete and was removed from the first line. Nomad 60 were transferred to the RAF in South Africa, of which 17 were lost en route. The survivors were supported by the SAAF in February 1941 for training missions. None of these devices experienced fire. They remained in service until the end of 1942 before being replaced by the Fairey Battle. The last Nomad were scrapped in 1944.

Note also that the A-17A 36-184 served in 1939 in the National Advisory Committee for Aeronautics (NACA) to test new models of motor fairing. In early tests, the A-17A was equipped with a large spinner covering the engine air intakes, which were replaced with air intakes at the wing root and for cooling the engine. However, before flight tests, ground tests indicated that the engine was not cool enough. NACA abandoned the project flight test in this configuration.

NACA removed the vents at the wings, and replaced the off spinner with a smaller, which had at its center a large hole with a sort of fan to force air to cool the engine. Cooling during ground tests proved more efficient than the standard system mounted on the A-17A series. After 15 minutes at full speed, the temperature never exceeded the limits. Although there was a slight decrease in speed with the fan system in the nose, flight tests are deemed inconclusive and NACA stopped the project. The 36-184 was restored to its original configuration and returned to the Air Corps June 21, 1940.

Another A-17A (35-122) was used by the NACA Langley Field tests for aerodynamic research, including exhaust pipes and laminar flow wings. It is unclear whether the aircraft was returned to the USAAC.

Export version of the A-17 and A-17A

Douglas DB-8A for Sweden

Spurred by the success of the series A-17, Northrop developed a series of versions for the export of its ground attack aircraft. Known at first as the Northrop Model 8, but the time it goes into production, Jack Northrop gave his division at the Douglas Aircraft. This branch of Northrop was known as the Douglas division of El Segundo, and therefore the export version was known as the Douglas 8A-8A or simply DB, DB meaning Douglas Bomber.

The first of this version was the Model 8A-1 or DB-8A-1. The Douglas Model 8A-1 was developed for Sweden, who commissioned a prototype parts for a second machine that will serve as a model for the production aircraft produced under license by AB Svenska Jarnvagsverkstaderna (ASJA) to Linkoping. 8A-1 was similar to the A-17 fixed train, but Sweden opted for a Bristol Mercury engine, since it was produced under license by the SFA.

The prototype (number 378 Production) used a Bristol Pegasus XII motor 875 hp, which was similar to the Bristol Mercury engine intended for production. He was ferried by boat to Sweden, April 22, 1938. The Swedish Air Force or Flygvapnet pointed this aircraft was registered 5A and B 7001. Parts of the second unit (No. 410 production) were shipped to their destination August 8, 1938.

The production version built by ASJA was known under the name Flygvapnet B 5B, and used a Bristol Mercury radial engine XXIV 9 air-cooled 920 hp (built under license by SFA) cylinders. The difference with the Northrop B 5A built in the USA, was the canopy driver had an arched shape and the radio mast was moved from the top of the canopy to a position just above the canopy driver.

64 B 5B were built by ASJA in 1940 and were assigned to the Flygvapnet under serial numbers 7002-7065.

In 1941, the ASJA was replaced by the Svenska Aeroplan AB or SAAB. SAAB awarded a contract for 39 B 5C (serial numbers 7066 to 7104).

B 5 fitted out the Flottiljer F 4 Östersund and F 12 Kalmar, before being replaced in early 1944 by light bombers SAAB 17.

Douglas 8A-2 for Argentina

The Douglas Model 8A-2 was an export-based A-17 fixed-track, designed by the Fuerza Aérea Argentina. the test pilot Eddie Allen did a demonstration of Northrop Model 5B in Buenos Aires in 1935, and 30 Model 8A-2 aircraft were ordered. They were built and sent by ship to Argentina in 1938.

The Model 8A-2 was powered by a Wright R-1820-G3 840 hp and armed with two 12.7 mm machine guns and two 7.62 mm mounted in the wings and a 7.62 mm machine gun in defense. The Model 8A-2 had a launch bomb partially retractable under the rear cockpit. The NO production was 348-377. FAA registrations were A-401 to A-430 (later O-401 O-430).

The Model 8A-2 entered service with the Fuerza Aérea Argentina in the Regiment of Attack No. 2, first in El Palomar and then El Plumerillo. The Model 8A-2 was replaced by the Argentine bomber twin I.Ae.24 Calquin. The survivors were transferred to El Palomar, near Buenos Aires, where they were used as training aircraft until 1955.

Douglas 8A-3P Peru

The Model 8A-3P was the export version of the A-17A-retractable landing gear for the Cuerpo de Aeronautical del Peru. The Model 8A-3P was different from the A-17A USAAC because of its radial engine Wright GR-1820-G103 of 1000 hp, and was equipped with more and more of a bomb thrower semi retractable identical to Model 8A-2 Argentina.

A total of 10 Model 8A-3P were built (production numbers 412-421). They served in the 31st Escuadron of Attack Reconicimemiento there. These aircraft were used in July 1941 during the war between Peru and Ecuador. The last Model 8A-3P was retired from active service in the late 1950s.

Douglas 8A-3N for Holland

The Douglas Model 8A-3N was the export based on the A-17A version built for Holland. It was equipped with an engine Pratt & Whitney Twin Wasp S3C-G 1100 c. The first copy flew July 31, 1939. A total of 18 units were commissioned in 1939. The order was delivered between August and November 1939.

Performers 8A-3N with construction numbers 531/548 received the Dutch serial numbers 381/396. They were assigned to the 3rd Squadron of the 2nd Aviation Regiment (3rd Ja.VA) based Ypenburg. The first model 8A-3N was lost in an accident before the war. May 10, 1940, when German forces began their offensive in the West, twelve DB-8A-3N entered service in Ypenburg, and five remained in reserve in: Ockenburg.

DB-8A-3N was destroyed on the ground during the initial attack of the Luftwaffe, but the other eleven planes were still able to fight. The DB-8A-3N was not expected to fight as a hunter, and seven were quickly destroyed by the Messerschmitt Bf 110 of the Luftwaffe. However, DB-8A-3N Dutch transport troops destroyed two Junkers Ju 52. After landing, the four DB-8A-3N remaining were all destroyed on the ground during another German raid.

The five DB-8A-3N reserve Ockenburg were captured intact by the Luftwaffe. In 1941, one of his captured aircraft was exhibited at the side of the Dornier Do X in Berlin. However, later in the war it was destroyed during an allied bombing.

Douglas 8A-4 for Iraq

The Model 8A-4 was based on the export of A-17A version built for the Iraqi government. 8A-4 was similar to 8A-3P Peru (including the launch bomb) and was equipped with a Wright GR-1820-G103 engine Cyclone 1000 c. The NO production for five 8A-4s ordered went 613 to 627. They were sent to Iraq between April and June 1940.

All DB-8A-4 were apparently destroyed by the Royal Air Force during the Iraqi uprising on May 2, 1941 Rashid Ali.

Douglas 8A-5 for Norway

The Douglas Model 8A-5 was the last version of the A-17A export. it was also the most powerful and most heavily armed in the series of single-engine ground attack Northrop / Douglas.

36 DB-8A-5N were ordered by Norway in early 1940. They were armed with four.30 caliber machine guns (7.62 mm) mounted in the wings, two.50 caliber (12.7 mm) in pods beneath the wing root and two twin.30 caliber machine guns for rear defense. A Wright GR-1820-G205A equipped with 1200 hp, this version could carry more than 816 kg (1,800 lbs) of bombs. The production numbers were: RnoAF 301/336.

8A-5s Model was used by the Norwegian Heerens Flyvevaben. Unfortunately, before the order is delivered, Sweden was occupied by the Nazis. 36 DB-8A-5 (715-750) were assembled and delivered in late 1940, the Norwegian government in exile in Island Airport (Ontario, Canada), also known as Little Norway.

Arrangements were made ​​for Norwegian pilots can enter in flight schools in the RAF and RCAF, and model 8A-5 was put into surplus. In August 1941, Peru offered to buy 18 aircraft from the Norwegian surplus, but U.S. State Department vetoed because he feared that they serve against Ecuador. He proposed that these aircraft were delivered to the Soviet Union under the law Leasing, but Norway and Peru refused.

As a result, 18 Model 8A-5 were purchased by the USAAF on December 9, 1941 under the name Douglas A-33-DE. They were assigned as numbers 42-13584/13601 series. They were used only for training in the U.S..

However, 13 Model 8A-5 Norwegians were delivered to Peru. USAAF designation A-33A and their serial numbers were assigned 42-109007/109019 for registration questions. They were delivered to Peru in June 1943, where they rounded out the Douglas 8A-3Ps already in service. They were assigned to the 31st and 23rd of Attack Escuadron there Reconicimiento of Fotogrametria based in Las Palmas. They remained in service until 1958, when they were replaced by Douglas B-26 Invader.

One of these aircraft is still on display at the front door of the base of Las Palmas.

Variants

Northrop A-17 or Northrop Gamma 2F: Production version with fixed landing gear equipped with a Pratt & Whitney R-1535 Twin Wasp Jr -13 to 750 hp. No. 35-51 to 35-160 series. 110 copies.

Northrop A-17A and Northrop Nomad: Version production retractable undercarriage with a R-1535-13 Twin Wasp Junior 825 hp. No. 36-162 to 36-261 series (1st generation) and 38-327 to 38-355 (2nd generation). 129 copies.

Northrop A-17AS: unarmed seater version of the A-17A for the transport of personality, with a Pratt & Whitney R-1340 -41 600 hp (Serial No.: 36-349) or R-1340 -45 to 600 hp (Serial No.: 36-350). 2 copies.

Douglas DB-8A: Export version of the A-17 for Sweden with a Bristol Mercury XXIV 920 hp. 105 copies (2 products in USA No. 378 and 410 series, with the remainder under license in Sweden).

Douglas 8A-2: Revision export of A-17 for Argentina with a Wright R-1820-G3 840 hp. Serial No. 348-377. 30 copies.

Douglas 8A-3P: Export version of the A-17A for Peru with a Wright GR-1820-G103 of 1000 c. Serial No. 412-421. 10 copies.

Douglas 8A-3N: Version of the A-17A export to Holland with a Pratt & Whitney Twin Wasp S3C-G 1100 c. No. 531 series 548. 18 copies.

Douglas 8A-4: Export version of the A-17 for Iraq with a Wright GR-1820-G103 Cyclone 1000 c. Serial No. 613-627. 5 copies.

Douglas 8A-5 or Douglas A-33: Export version of the A-17 for Norway with a Wright GR-1820-G205A 1 200 hp. No. 715-750 series. 36 copies.

User countries

South Africa

South African Air Force received 57 aircraft in Britain under the name Nomad I.

Argentina

Argentina receives 30 Model 8A-2s in 1938. Replaced by the first line in: I.Ae. Calquin 24, retired from active service in 1955.

Canada

Royal Canadian Air Force received 32 aircraft originally ordered by France.

The United States

Army Air Corps received 110 A-17 divided into the following units:  3rd Attack Group based Barksdale Field

17th Attack Group based at March Field

16th Pursuit Group based in: Albrook Field 74th Attack Squadron

General Headquarters Air Force, who used A-17AS to transport his generals.

France

Air Force control 93 devices that will eventually come to England and Canada. Iraq

Iraq buys 15 Model 8A-4s, which will be destroyed in 1940 during the Anglo-Iraqi War in 1941.

Netherlands

Holland 18 Model 8A-3Ns in 1939. The majority is destroyed by the Luftwaffe on 10 May 1940, the first day of Operation Weserübung.

Norway

Norway ordered 36 Model 8A-5ns in 1940. 18 will be sold in Peru, but blocked by the U.S. they will be seized under the designation A-33. Norway still sells its latest handsets in Peru in 1943.

Peru

Peru order 10 Model 8A-3P, which will experience fire during the Peru-Ecuador war in July 1941. The survivors will be completed by 13 Model 8A-5s purchased from Norway in 1943. They will remain in service until 1958.

Sweden

Sweden bought the license to produce 63 B 5B and 31 B5C from 1938 to 1941. They will be replaced in 1944 by SAAB 17.

United Kingdom

The Royal Air Force received 61 aircraft ordered initially by France and redesignated as Nomad 57 but I will be transferred to South Africa.

China  Republic of China

Survivors

A-17A (36-0207) is always visible to National Museum of the United States Air Force in Dayton (Ohio).

References

Ray Wagner, American Combat Planes, Third Enlarged Edition, Doubleday, 1982.

Gordon Swanborough and Peter M. Bowers, United States Military Aircraft Since 1909, Smithsonian, 1989.

Rene J. Francillon, McDonnell Douglas Aircraft Since 1920, Volume I, Naval Institue Press, 1988.

Alain J. Pelletier, Northrop’s Connection – The Unsung A-17 Attack Aircraft and Its Legacy, Air Enthusiast, May / June 1998, No. 75.

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