The CW-21 was designed during the late 1930s. It combined light weight construction with a powerful engine, which resulted in an excellent rate of climb and manoeuvrability, allowing the fighter to quickly reach the height of attacking enemy aircraft, and attack them. The prototype was sent to China as a demonstration copy and an order for three aircraft, plus a further 32 as kits, followed. These would be assembled locally. Only the three production machines arrived in the chaos of war and would never see actual combat. A second modified variant was ordered by the Dutch government and 24 were delivered to the Netherlands Indies. The CW-21s were outnumbered and outgunned when the Japanese launched their attack on the Netherlands Indies. Despite the poor outlook, the pilots flying them put up a good fight...

When Hungary got involved in the second world war, the WM-21 Solyom (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 in 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 Solyom 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.