The Polikarpov U-2 was the most produced aircraft to serve in WWII (40,000+ built). It was used in all sorts of applications including as a bomber. Since its cruise speed was much slower than the stall speed of any German fighter in service from the start of Barbarossa, German fighters sometimes had trouble intercepting it.
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Yeah, the Ruskkies used them for night raids on front line German airfields...
...the Germans looked on them with disdain and some humor because they would fly along at low alt, drop a couple of 50lbs bombs and even grenades on the fields...injure a few people, damage some equipment, etc...regular "washing machine charlie" is all that thing was.