The R-Z or R-Zet was developed at the aircraft factory GAZ No 1 at Moscow as a development of, and a replacement for the Polikarpov R-5, the standard light reconnaissance bomber of the Soviet Air Force. Based on the R-5SSS, the most advanced variant of the R-5, the R-Z had a new, deeper, monocoque fuselage, with a sliding canopy for the pilot and fixed glazed fairing for the observer. The 544 kW M-17F engine was replaced with the 611 kW M-34 engine. The R-Z first flew in January 1935 and was accepted for the Soviet Air Force in preference to the competing Kochyerigin LR, also an R-5 derivative. By the time production finished in spring 1937, 1,031 R-Zs had been built.
Operational history
Like its predecessor the R-5, the R-Z was used in large numbers by both the Soviet Air Force and Aeroflot. Its first use in combat was during the Spanish Civil War from 1937. 61 R-Zs were delivered to the Spanish Republican Air Force, where they were nicknamed Natacha. These were heavily used, flying in tight formations and using co-ordinated defensive fire to defend against fighter attack, while returning individually at low levels. Despite these protective measures and the Soviet fighters escort, the R-Zs were easy prey for the FIAT CR.32s, the main fighter of the Nationalists. On 14 July 1937, in the Brunete sector, on the extreme left of the Nationalist Madrid Army Corps, the squadron of Spanish ace Joaquín García Morato intercepted a squadron of R-Zs escorted by a number of Polikarpov I-16s Rata. The Nationalist pilots dived through the fighters escort, and attacked the R-Zs, shooting down five. On 24 December 1938, another group of CR.32s, still led by Morato, while escorting Junkers Ju 52s and Savoia Marchetti SM.79s, spotted a formation of eleven R-Z "Natashas" from the 2ª Escuadrilla, Grupo 30 escorted by Ratas, over Cap de la Serra. The Nationalist pilots dived to attack, and in a few minutes they destroyed nine of the R-Zs. Jackson 1979, p.24. Although many R-Zs were damaged by ground fire, and the 2ª Escuadrilla, Grupo 30 lost 9 of their 60 aircraft in one day on 24 December 1938, overall losses were relatively low with 36 of the 61 delivered surviving to be captured by the Nationalists at the end of the war in April 1939. R-Zs were used by the Soviet air force against Japan above Mongolia in the Battle of Khalkhin Gol in 1939, and the Winter War against Finland in the same year. By the time of the German invasion of the Soviet Union in June 1941, the R-Z was in the process of being replaced by the Ilyushin Il-2, although it remained in service with a number of light bomber regiments.
