First flown in the spring of 1939, it was to become the standard training aircraft of the Polish Air Force's fighter pilot schools before more advanced trainers could be delivered.

In late 1936 Antoni Zagórski of the Warsaw-based PZL works designed a simple trainer and sports plane powered by a Train engine.

[1] The PWS further modified the design, now named PWS-40 Junak, with several features cloned from a Tipsy S.2 sports plane bought the previous year for testing; additional influence came from British de Havilland DH-94 Moth Minor.

[1] Equipped with a much more powerful engine delivering 176–221 kilowatts (236–296 hp), the new aircraft was to have a smaller wingspan (9.5 metres (31 ft)), flaps and a retractable landing gear.

[1] The designers also envisaged an advanced fighter trainer, armed with machine guns and powered with a 331 kilowatts (444 hp) engine.