The Polikarpov R-5 was a biplane reconnaissance aircraft and light bomber that was produced in vast numbers in the Soviet Union in the pre-war years, but that had largely disappeared from front line units during 1941.
The R-5 was designed while Polikarpov was working as the chief designer at Moscow's No.25 Factory. It was designed to be simple to fly, have a long life and be of wooden construction. It was designed around the BMW VI inline engine, which then entered licence production in the Soviet Union as the M-17.
The R-5 had a fuselage built around four pine longerons, with twelve pine and plywood frames. The engine cowling and upper decking of the forward fuselage were aluminium, while the rest of the fuselage was covered with plywood. The upper wing was larger than the lower, and was built in three sections with a fuel tank in the centre section. The wings were of parallel chord (straight leading and trailing edges, with an equal width all along their length) and with roundted tips. The box spars and ribs were made of pine and birch plywood, and they were fabric covered apart from the leading edges, which used ash.
The prototype and early production aircraft used the BMW VI 12-cylinder liquid cooled inline V engine, while most production aircraft used the licence-built M-17. The prototype was armed with a signle fixed forward firing PV-1 machine gun and one flexibly mounted DG-2 machine gun in the observer's position, although many production aircraft carried wing rear guns.
The prototype was built at Zavod No.25 in Moscow and was test flown during 1928. It then went for state acceptance trials from October 1928. Production began in 1930, although only thirty aircraft were delivered in that year. That rose to 300 aircraft in 1931, 660 in 1932 and 1,150 in 1933, and eventually 4,914-4,995 aircraft were built over six years (excluding the R-5SSS and R-Z).
The R-5 began to replace the Polikarpov R-1 and the Tupolev R-3 in 1930, and in 1931-32 nine reconnaissance, eleven light bomber and seven light attack units received the type. It was also issued to special units, to corps flights and to training schools. By 1941 it was being phased out of front line units, and although thirty-two units still had it at the time of the German invasion, the remaining aircraft had been moved to second line duties by the end of the year,
The R-5a was a floatplane version of the R-1 that replaced the Polikarpov MR-1 floatplane in service. The floats were constructed around sixteen steel-tube struts with wooden floats made of ash and pine. The prototype was built in 1930 and made its maiden flight on 31 December 1930. State trials were delayed until 1932, and the aircraft was in service from 1933. Around 111 were built.
The R-5T was a single-seat torpedo bomber developed in 1932-33. In order to make space for the torpedo a new split undercarriage had to be designed, and extra bracing struts put in place to cope. The prototype was built in 1933, and fifty series aircraft delivered by 1935. The R-5 served around the Soviet Coast for a short period, and the last aircraft, in the Far East, were withdrawn around 1938.
The R-5Sh was a ground attack (or shturmovik) version of the aircraft. It was armed with one fixed forward firing DA machine gun, a twin DA machine gun in the observer's position, and four obliquely mounted PV-1 machine guns mounted in fairings below the lower wing. It could carry up to 500kg of bombs and had extra armour plating. At least 100 were built, starting in either 1931 or 1933.
The R-5SSS was a lightened, more streamlined version of the R-5. The SSS designation stood for skorostnoi, skoropod'emnoi, skorostrel'nyi, or fast, fast climbing, fast firing. A 715hp M-17f was used, and weight was reduced by using spruce wing spars. Some features were streamlined. Top speed increased by 30kmh and the ceiling also improved. Fast firing was achieving by replacing the PV-1 machine guns with the much faster-firing ShKAS model. The SSS also had an interal bomb bay, and was produced in a ground attack version with four more machine guns in the lower wings. Over 600 R-5SSS aircraft were produced between 1935 and 1937.
The R-Z was a major redesign of the basic aircraft, produced by D S Markov and A A Skarbov at Zavod No.1. It used the same basic layout as the R-5, but with a modified fuselage, smaller dimensions and lighter structure. The aircraft was powered by the 850hp M-34N engine. It was armed with two fixed and one flexibly mounted ShKAS machine gun, and up to 500kg of bombs, and was also produced in a ground attack version with four fixed machine guns below the wings. Speed increased from 143mph to 196mph. A total of 1,031 R-Zs were built at Zavod No.1 between 1935 and 1937.
Wing span: 15.5m/ 50.85ft
Length: 10.56m/ 34.65ft
Height: 3.62m/ 11.87ft
Empty Weight: 1,969kg/ 4,349lb
Loaded Weight: 3,247kg/ 7,158lb
Max Speed: 228km/h/ 141mph
Service Ceiling: 6,400m/ 21,000ft
Range: 800km/ 497 miles
Armament: One fixed forward firing and one or two flexibly mounted 7.62mm machine guns.