When Hungary got involved in World War II, the WM-21 Sólyom (Falcon) was the only Hungarian designed and manufactured plane in service with the Hungarian Royal Airforce. It was in widespread service as reconnaissance plane starting from 1938 onwards. In June of 1941, the machines failed to make an impression, mainly because of accidents and technical issues. The planes were diverted to the training role and were still used as such by May 1945.

The Sólyom story starts in 1927, with the Fokker C.V, of which the Hungarian Royal Airforce had acquired 76, mostly built under license by Manfred Weiss (WM). WM improved the C.V, which resulted in the WM-16, with 18 built in two variants. This WM-16 paved the way for the WM-21, of which 128 examples were built.