This is a heavily modified Let C-11 (Yak-11) trainer now powered by an Allison engine. Ex N9YK which still had a radial engine. It was then called a Yak-9 but this seems to make no sense as the trainer was based on the Yak-3 while the Yak-9 was a slighty larger and heavier, all-metal fighter which never used a radial engine.