I have been watching the DVD of Dark Blue World the film about Czech fighter
pilots in WW2.

In the first scenes of the movie the pilots are training in Czechoslovakia
before the German invasion. Several of the aircraft are clearly Bucker
Jungmann types but there is another that is different. The rudder is more
rounded than the Bucker but the aicraft does have an inverted in line engine.
What aircraft is this?

John Dupre'