I was beginning to think that I had imagined this aeroplane.
Congratulations Mel, it is the Hopfner-Hirtenberger HM-13/34. Designed in 1934 as a fighter/trainer by Hopfner Flugzeugbau GmbH of Austria. In 1935 Hopfner was taken over by Hirtenberger Metallwarenfabrik A.G. and the aircraft was completed as the Hopfner-Hirtenberger HM-13/34. The power unit was a 410hp Fiat A.20. It did not arouse much interest with the “newly formed” German Luftwaffe who preferred to use German aircraft. However, three aircraft (Nr. 52 (OE-FAH/D), Nr. 53 (OE-FEH/D) and Nr. 54 (OE-FIH/D)) were built. After the Anschluss of 1938 these were absorbed into the German Luftwaffe. Their fate is unknown.
Mel has control.