The prototype of the U-2 aircraft was developed at the design bureau of Nikolai Polikarpov. It was a single-engine biplane of entirely wooden construction; the aircraft was test-flown in January 1928. After minor corrections to the design, the U-2 was ordered into mass production.
A number of variants adapted for different purposes and climatic conditions were built. Ambulance, agricultural, executive, transport and passenger versions appeared. In the USSR, over 33,000 U-2 and Po-2 aircraft were built. Due to ease of handling, simple maintenance and flight safety, this type was operated in various variants for many years.
After the outbreak of hostilities on the Eastern Front in 1941, one of the most interesting variants of the U-2 appeared — the light night bomber. The new version was armed with one machine gun and a bomb load of 200 to 300 kg. This caused a decrease in performance; however, during night attacks behind the front line, using the element of surprise, heavy losses could be inflicted on the enemy. In 1944, the name was changed to Po-2. Towards the end of the war, Po-2 aircraft entered service with the Polish air force in the USSR.
The first Po-2 assigned to the Polish military air force was a three-seat aircraft placed at the disposal of General Zygmunt Berling. Bomber-version Po-2s entered service with the 2nd Night Bomber Regiment “Kraków,” which from September 1944 took part in the battles for Warsaw, and later on the Pomeranian front and in the Berlin operation.
In 1947, for political reasons, the decision was made for Poland to purchase a licence for the production of these aircraft. The Central Aircraft Design Office in Warsaw was ordered to prepare the production documentation for the Po-2. In 1949, production began under the name CSS-13 at the works in Mielec and Warsaw, where an ambulance variant of this aircraft named S-13 was also developed. In total, approximately 550 CSS-13 and S-13 aircraft were produced in Poland between 1949 and 1955.
The specimen exhibited at the Museum, with factory number 641-646, was produced in 1944 and towards the end of the war flew with the 2nd Night Bomber Regiment “Kraków.” After being struck off charge, it was transferred to the collection of the Museum of Communications, from where in 1963 it was transferred to the Aviation Museum in Kraków. This bomber-version Po-2 is unique on a global scale.
| Wingspan | 11.4 m |
| Length | 8.17 m |
| Takeoff weight | 1368 kg |
| Maximum speed | 130 km/h |
| Ceiling | 1300 m |
| Range | 350 km |
| Armament | ShKAS machine gun cal. 7.62 mm, 300 kg of bombs |
| Engine | 5-cylinder, air-cooled radial M-11D with a power output of 125 hp (92 kW) |
