It was the first Polish aircraft fitted with slats.
Furthermore, the Polish aircraft and their engines were worn out from intensive service use.
It was the last flight of a Polish aircraft during the Polish September Campaign.
It was the second most numerous Polish pre-war aircraft, after the RWD-8.
About half survived until 1939, they were longest serving Polish aircraft of wooden construction.
No points were given to the British, Polish or French aircraft.
In both last trials, the Polish and French aircraft performed poorly as well.
On 12 September 1939 he was attacked by a Polish aircraft which shot out his starboard engine.
Apart from his test pilot work, he took part in numerous aviation contests and presentations of Polish aircraft abroad.
Polish aircraft were imported and some were built in China.