During the mid-1930 the Argentinean Dirección General de Aeronáutica (General Direction of Aeronautics) decided to replace their ageing Dewoitine D-21 fighters sold by France during the 1920s, with newer models. By 1927 there were just eight D-21 fighters and planned license production fell through due to the economic crisis. However, the rights to produce the Curtiss Hawk II were acquired, marking Curtiss' first incursion into the Argentine market. In 1934 the Curtiss Hawk III biplane fighter, competing against the Italian Fiat Cr.30, was demonstrated to the authorities, but none of them ultimately managed to replaced the old Dewoitine D-21s.
In 1935 Argentina began to emerge from the economic crisis, with funds available to resume equipment purchases. This time, however, an official competition was announced, with 21 companies from Europe and the United States submitting their bids, as there was plenty to compete for: Argentina intended to purchase 70 fighters, 67 bombers and 30 trainers. Although the Hawk III had already been purchased as an interim fighter, the competition was officially open in Buenos Aires on 23rd March 1936.
As the result of comparative tests performed at the time, only American aircraft were selected: The Northrop 8A-2 and the Martin 139 bombers plus the North American NA-164P trainers. The Hawk IV (commercial name for the fixed-landing gear variant of the Hawk 75) generated interest too, so a demonstrator was ordered. The final choice was to be made in the next competition in 1937, however the deal unfolded somehow different than before as every European contestant withdrew. The Germans, in particular, were displeased with the cancellation of their aircraft, sparkling with this heated diplomatic exchanges between Buenos Aires and Berlin.
Eventually it turned out that in 1937, American companies had no opponents and the Curtiss Hawk 75 topped the list of contenders, followed by the Seversky P2A, which could function both as a fighter and a trainer. Seversky also decided to demonstrate their P-35 fighter.
The Hawk offered to Argentina was a variant of the one offered to China, the H-75H. It was completed together with the first example and later presented to Chiang Kai-Shek with the registration NR 1277. However, this second "steel chasis" Hawk differed significantly from the first H-75H. First, the Y1P-36 airframe was adopted as a basis, instead of the Hawk 75B, except for the engine) and, therefore, NR 1277 had glass panels behind the cockpit canopy. It was armed with four 7.62 mm machine guns, two in the fuselage and two in the wings. It was equipped with a ventral bomb rack which could carry a single 227 kg (500 lb) bomb. Additional racks were located under the wings, for ten 13,6 kg (30 lb) or six 22,7 kg (50 lb) bombs each. This aircraft arrived in Argentina in June 1937 and was known as the "Argentine Demonstrator", and outclassed its main rival, the Seversky 2PA.
During the early stages of the competition, Seversky's fighter was damaged and, in order to save the situation, they promised to send another P-35, Curtiss, which had practically won the contest, began to fear that the new competitor would delay the Argentine decision. This eventually proved to be the case and on 30th January 1938 a decision was made to purchase 30 Hawks, with a production license of 20 machines to manufactured at FMA's (Fábrica Militar de Aviones - Military Aircraft Factory) plant in Cordoba.
This decision put an end to Curtiss' stress, when it was discovered that a German Bf.109 fighter, which was around 80 km/h (50 mph) faster than the Hawk, was located in Brazil and it was bound for Argentina, to take part in the contest and win the contract. Eventually, it was found that Messerschmitt's aircraft was not a Bf.109 but a Bf.108 liaison plane, which could achieve only 187 km/h (117 mph).
The aircraft manufactured in Argentina were designated as Hawk 75O. Materials and equipment were purchased from the United States, with assistance from Curtiss. All navigation equipment, flight instruments, engines and armament were also imported to Argentina.
With the gradual establishment of a production line in Argentina, the presence of the "Argentine Demonstrator" became unnecessary, and it was decided to return the aircraft to the United States. The ferry flight was to be used to attract attention from the countries the fighter was going to flight through, specially Chile, Ecuador and Peru. Piloted by Captain Grey, it took off from Buenos Aires, bound to Santiago de Chile, on 5th March 1938. However, it could not reach its destination due to poor weather conditions and landed in Mendoza, Argentina. The pilot waited for the storm to clear and took off again. Unfortunately, during the climb-out, at an altitude of just three meters (9ft) the engine failed and the "Argentine Demonstrator" crashed. Fortunately, Gray escaped without major injuries.
The production version of the Argentine Hawk 75O differed from the "demonstrator" in many aspects. It was powered by either a Wright GR-1820-G3 radial engine rated at 875 hp of at take-off or a GR-1820-G5 which was equally rated. The engine was equipped with an E.160 electric starter, which could be manually started if needed.
It was equipped with a Telefunken Type 274 radio gear. Armament consisted on three 11.35 mm Madsen machine guns, two in the wings and one in the fuselage. The ventral bomb rack was eliminated, but under-wing ones were not. The airframe was identical to NR 1277, although carriage strut fairings were changed to larger and fully enclosed ones - similar to those present on the Thai Hawk 75N. The surface finish was also improved by the addition of countersunk rivets and the sheet metal was polished to a mirror-like shine, allowing for a 10 km/h (6 mph) increase in top speed.
Between 29th November and 15th December 1938 the first 29 machines were manufactured at Curtiss plant in Buffalo, New York, although Argentine documents mention 30 machines received. The disassembled fighters were sent to the Dirección del Material Aeronáutico del Ejército (Army's Aeronautical Material Directory), where they were assembled and equipped. In the meantime, the FMA factory was preparing to begin independent production, which began in August 1940. On 16th August the first Argentinian Hawk 75O rolled off the assembly line. Over the following months 19 more joined the production line, rolling off the line at a rate of one per week. Some of these were equipped with gun cameras.
After the end of H-75O production, it was intended to begin the construction of fifty Hawk 75A aircraft with improved engines, equipment and armament, while the production rate of the H-75O was also in mind. In fact FMA factory was expanded to achieve the production rate of one H-75O per day but, eventually, further manufacturing of this aircraft in Argentina was abandoned.
The Hawk 75O served in the Regimiento Aéreo Nº2 (Air Regiment No.2) under Argentine Army Aviation Command. In July 1944 with the foundation of the Argentine Air Force as a separate branch of the army, they received new codes with the letter "C" in front of the aircraft number. They lived a long lasting career in Argentina as in December 1951 there were still sixteen of them in active service, as part of Grupo 1 de Caza (Fighter Group No.1) and in 1952 they were assigned to VII Brigada Aérea de Morón (7 Moron Aerial Brigade).
The Hawks were gradually written off active service in 1949 when the Gloster Meteor was purchased.
According to some sources the last Hawk 75O was scrapped in 1954, while other claim that in 1955 some few surviving ones were present at Jorge Newbery airport (Buenos Aires) during the Revolución Libertadora, a coup d'état which overthrew President Perón, although not in use.
Sources:
1st AJ-Press - Monografie Lotnicze 61 - Curtiss P-36 Hawk Part 1 (translated)
2nd https://www.amilarg.com.ar/curtiss-hawk-75.html (translated)
