Mel's Challenge
Well we seem to have reached a stalemate on this one time for a re-cap.
It was built in Czechoslovakia. It was powered by a horizontally-opposed 'Doris-B' engine. The prototype first flew 1956 and the production model flew a year later. It is reported that it went into production for the Czech Air Force but I am unable to confirm that.
A regular contender of this quiz has identified the aircraft.
Mel