Looking through the article written by the Yugoslavian engineer, Svetopolk Pivko, I would agree on the hypothesis of an ultra STOL project. Here's a translation of the last part of the article, which may sum up what it was all about.
'In U.S based on the results of our experiences, we established the preliminary project of a twin-engine airplane (weight 1460kg., power2X300 =600 CV .; diameter of the propellers 2,62m.). The calculation of performance shows that this device test could rise on site and rise vertically at full throttle, with a speed of the order of 2 m / s. Its speed of cruise during the horizontal flight would of the order of 300 km.-h. and more. Another tester (weight 2,300 kg., power 2X450 = 900 CV., diameter of the propellers 3.18 m.), could also fly vertically with a speed of 0.9 m / s. We are convinced that the experiments that we have carried out will also open the way to new research, with the aim of obtaining a greater security through the realization quasi-vertical takeoffs and landings and possibly the possibility of very low speed flights.'