Potez 39

The Potez 39 was designed to a fulfil a requirement issued during 1928 for an aircraft to replace both the Potez 25 and Breguet 19 aircraft then in service with the French Air Force in the A2 (Artillerie Biplace - two seat observation aircraft) role. One key feature that was stipulated by the specification was the use of the Hispano-Suiza 12H engine, which was capable of producing up to . During January 1930, the prototype conducted its maiden flight. Although the Breguet 27 was selected as the winner of the competition, both it and the Potez, which was the runner-up, were chosen for production. Compared to the Potez 25, of which over 2,000 were ordered, production of the Potez 39 series was on a smaller scale. A total of 100 Potez 390 aircraft were built for France while 12 Potez 391 aircraft, powered by a Lorraine-Dietrich 12H engine capable of generating up to 700 bhp, were produced to the Peruvian Air Force. A number of prototype and development aircraft, including a floatplane, underwent flight testing, however, no further orders were received. ==Design==

The Potez 39 was a dedicated aerial reconnaissance aircraft that featured all-metal construction, which included the coverings of both the fuselage and wings. The aircraft had an oval-section fuselage that was formed out of two areas, the fuselage proper and the engine support. These spars comprised a duralumin web and four steel corrugated angles for stiffening, the latter being relatively easy to uniformly construct, as well as being relatively resistant to rusting and vibrations alike. Both weight and construction time were minimised via the minimisation of both joints and riveting. The Potez 39 had a parasol wing, the basic form of which was of an elongated rectangle with well-rounded tips, a feature which reportedly obtained the maximum achievable efficiency without resorting to a more complex wing design that incorporated multiple decreasing profiles. The wing was equipped with sizable ailerons. It was operated by a crew of two, a pilot and observer, that sat in tandem in open cockpits. The aircraft was powered by a single Hispano 12H, which produced 579 hp at 2,000 rpm. The fuel dumping mechanical was relatively simple, being stylised on that of a firearm. The aircraft was equipped with a conventional undercarriage. The tail unit of Potez 39 was directly attached to the sternpost, which was in turn carried by the aftermost frame of the fuselage frame; the rear of this sternpost supported the hinges of the unbalanced rudder while the front received the fin. The rear of the stabiliser was attached to a movable support that permitted mid-flight adjustments with relatively little force via an arrangement of flexible joints and ball bearings. The elevator, which was positioned in front of the rudder, was unbalanced, slightly tapered, and had well-rounded tips; its structure was akin to that of the wing as well as covered by duralumin. ==Operational history==

Deliveries to the French Air Force began in August 1933 and continued until April 1935. The Potez 39 joined the French Air Force's ''Groupes d'Observation (GO), but from 1936, it was replaced in the GOs by more modern types, including the ANF Les Mureaux 117, Amiot 143 and Potez 540 aircraft, with the Potez 39s transferred to second-line Groupes Aériens Régionaux (GAR), which had the principal role of training reservists. In 1938, the GARs were redesignated Groupes Aériens d'Observation'' (GAO). In August 1938, during the Munich Crisis,General Joseph Vuillemin, Chief of Staff of the French Air Force, gave orders that, in the event of war breaking out, obsolescent observation aircraft such as the Potez 39 should never cross the front line. At the outbreak of the Second World War, the Potez 39 was in service with seven GAOs, which despite their age and Vuillemin's 1938 instructions, were deployed on operational missions. The Potez 39 proved to be vulnerable to German fighters, however, and in October 1939, the units equipped with the Potez 39 and the equally outdated Breguet 27, were withdrawn from use at the front. The Potez 39 continued to be used for liaison and casualty evacuation duties until the Battle of France concluded with the armistice of June 1940, at which point 41 aircraft reportedly remained in Metropolitan France. These aircraft were deemed to be obsolete and thus were scrapped shortly thereafter. Twelve Lorraine Pétrel-powered Potez 391s were purchased by Peru in 1933, during the Leticia War with Colombia, with the purchase being funded by popular subscription, but they only entered service early in 1935, after the war had ended. The outbreak of the Second World War stopped deliveries of spare parts and technical assistance from France, and the type was phased out from active service. ==Variants==

;Potez 37 :Two seat reconnaissance aircraft developed in parallel with Potez 39, with narrow tail boom replacing conventional rear fuselage. Unsuccessful, with only three built, the ANF-Les Mureaux 110 being preferred. ;Potez 390 A2 : Two-seat observation aircraft for French Air Force. Powered by a Hispano-Suiza 12Hb engine. ;Potez 39 Hy :Experimental floatplane version. ==Operators==

; • French Air Force ; • Peruvian Air Force ; • Soviet Air Force - One aircraft, used for tests and trials. ==Specifications==