The first prototype was flown in early 1936 (according to newest research, earlier given date December 1935 is wrong). It won the contest over the Lublin R-XXI project and the PWS factory project, but factory trials showed that its performance was still not satisfactory. In 1937 two modified prototypes were built, designated RWD-14a, but both crashed during trials that year due to steering mechanism faults (the pilots survived). Finally, in early 1938 the fourth improved prototype, designated RWD-14b, was built. After successful trials it was ordered by the Polish Air Force, receiving the name Czapla (Polish: "heron"), but due to a long development process, it was regarded as only an interim model, to replace the R-XIII until the advent of the more modern LWS-3 Mewa. In return for refunding the development costs, the DWL gave the rights to produce the RWD-14b to the state factory LWS ("Lubelska Wytwórnia Samolotów" – Lublin Aircraft Works, a successor of the Plage i Laśkiewicz).