In the late twenties of the 20th century, Nikolai Polikarpov was tasked with designing a successor for the U-1 trainer. In 1928 M. Gromov test-flew the prototype designated “U-2”.
The new design was a success and soon afterwards the aircraft was mass-produced in the “Krasnyj Liotchik” works near Moscow. The new machine seemed to perfectly suit the Russian aviation industry capabilities of that time – it was simple, of wooden construction, and covered with fabric. The bi-plane arrangement ensured good handling in the air, while the rugged undercarriage was its great asset when operating from dirt airfields.
The five-cylinder M-11 engine rated at 73 kW/100HP (at a later date replaced by the M-11D, which produced 92 kW/125 hp) was reliable and had a decent fuel consumption. The aircraft was not a racer by any means, but that was irrelevant for the training purposes. It had a short take-off run and big wing area, the latter feature being invaluable for prolonged gliding.
Many sub-variants stemmed from the basic design: passenger, liaison, ambulance, psychological warfare, crop-dusting, experimental maritime, as well as the LNB (light night bomber). In 1944 the aircraft was re-designated as Po‑2, its new designation followed by a single-letter suffix, which corresponded to a specific purpose of each of the aforementioned variants.
During the WWII the aircraft was extensively used for evacuating the wounded, dropping supplies, and as the commanders’ personal means of transport. Many more performed the reconnaissance and artillery fire correction missions and, last but not the least, the night hit-and-run bomb raids Po-2 got famous for. The aircraft’s ability to glide with its engine off enabled a stealthy approach and surprise attack. Its bomb load matched up to three-fourths of what the purpose-built assault Il-2 could carry along. The Germans christened Po-2 the “Night Witch”, while the Russians called it “Kukuruznik” (corn cutter) or “Lesnik” (forester). The Poles who flew it usually referred to it as “Pociak” (a colloquial name derived from its official designation “Po-”). Despite high vulnerability to ground fire and a rather symbolic defensive armament, the aircraft remained in active service throughout the war.
Paradoxically, its small speed was its best defence against air threats – it flew at the stall speed of the contemporary German fighters, which left an enemy pilot with very little time to line Po-2 up in his gunsight. The very same problem, only even more accentuated, was experienced by American fighters during the Korean War. Hardly detectable by radars due to its wood-and-fabric construction, it became a real nightmare for its opponents. Nevertheless, flying at the tree-top level to avoid attacks from beneath, Po-2s were extremely vulnerable to even small-arms fire.
The first Po-2 delivered to the Polish Army was a three-seater with hooded cockpit, presented to Col. Zygmunt Berling by Stalin in 1943. One year later, the Polish Air Force units activated in USSR received the following variants of Po-2:
Po-2 WS (liaison) – operated by the 17th Autonomous Liaison Command.
Po-2 LNB (light night bomber) – by the 2nd Night Bomber Group “Kraków” (Cracow).
Po-2 S (ambulance) – by various units.
Po-2 PS and SP (passenger) – by various units.
After the war, the aircraft was manufactured under licence (only with some minor modifications) as CSS-13. Its production run reached nearly 550 aircraft. Those were still in use by some flying schools as late as the seventies. A few Po-2s are private-owned and remain airworthy until present day.