Spain. Hispano-Suiza HS-42 and Hispano Aviation HA-43
During the Spanish Civil War the airline company Hispano started the construction of Fokker D.XX fighters for the Republican air force, although none were completed. At the end of the war, the Spanish Air Force considered the D.XXI outdated but commissioned Hispano to develop an advanced trainer based on that aircraft.
The HS-42A was the initial version with Piaggio engine. The Italian engine gave bad results and the HS-42A had to be remotorized.
The HS-42B, with Cheetah, was the most numerous version . In addition to the new construction, most HS-42A were converted to the B version.
The HA-43 (Hispano Aviación) had retractable landing gear and was to have a Spanish "Sirio" engine, but due to delays it had a Cheetah engine. They ordered 40 units, but the HA-43 had no better performance than the HS-42 and one of the prototypes crashed. The HA-43 was cancelled and the built specimens were transformed into HS-42D, with fixed landing gear.
Just over a hundred were builts. They were dangerous aircraft, prone to the "hachazo" ("axe strike", or asymmetric stall) and caused quite a few accidents. They were withdrawn in 1958 when American planes were received.