In the summer of 1939 the third, heaviest variant was chosen by the Polish Navy and a wooden mock-up was completed for aerodynamic trials. The designers also received 150.000 Polish złoty for the prototype, which was to be completed by mid-1940. The first serial run was to be started in 1940 and by early 1942 the Naval Air Squadron was to receive the first 12 planes. However, the Nazi and Soviet invasion of Poland and the outbreak of World War II interrupted further works.
