Polikarpov R-5

An unequal-span two-seat biplane constructed largely of wood with fabric covering, the R-5 reconnaissance light bomber flew in prototype form in 1928. Pilot and observer/gunner were seated close together in tandem open cockpits - the pilot beneath a cutout in the upper wing trailing-edge. The BMW VIb in-line engine of the prototype was replaced by the 507kW Soviet-built M-17B in production aircraft. The R-5 could operate on skis or twin-floats (the latter designated R-5A or MR-5), as well as on the more normal axle-type fixed undercarriage. Standard armament was a fixed 7.62mm PV-1 machine-gun and a DA-1 weapon of the same calibre operated by the observer. Up to 250kg of bombs could be carried on underwing racks.

Many variants of the R-5 were used in the Soviet Union. These included the single-seat R-5T torpedo bomber; the heavily armed R-5Sh ground-attack aircraft; and the SSS of 1934 with 533kW M-17F engine, spatted landing gear and new ShKAS machine-guns. Civil versions were the P-5 and P-5A, the latter with cabin accommodation for four passengers, and an enclosed pilot's cockpit.

Some 7,000 of all versions of the R-5 were built. Military operations included the Spanish Civil War (31 R-5s serving with the Republicans), the campaigns in 1938-39 against the Japanese in the Far East, the 'Winter War' against Finland, and the fighting against Germany from 1941. At the time of the German invasion most R-5s had been relegated to training and liaison duties, but several hundred returned to first-line duties to equip light night-bombing 'nuisance raid' units alongside the ubiquitous Polikarpov U-2.