In 1945, following World War II, Czechoslovakia, which had been the location of several Messerschmitt Bf-109 manufacturing plants, found itself with a substantial stock of unused Bf-109 components. In need of an air force, Czechoslovakia decided to use this stockpile to build it's own fighter aircraft, which it named the Avia S-199. Initially built purely from existing parts stocks, the aircraft gradually evolved into something unique. For example, when engine DB605 engine stocks ran out, the Jumo 211F was used, changing the aircraft's appearance substantially.
Aside from the visible engine change, the most notable external differences between the original Bf-109G and the final S-199 were gear axles that made the main gear wheels vertical when on the ground, and the sliding canopy. The cockpit was altered here and there, the most noticeable elements there being the replacement of the gun cover with a baggage compartment, the inclusion of a VSI, and new Revi gun sight mount and gun round counter.
Later types also used the second fuselage tank, formerly for the MW boost, as a second fuel tank, giving better range. Drop tanks were normally only for reconnaissance versions.
The Israeli version from 1948 represents an intermediate type, still with the old Erla canopy and canted main gear wheels, along with the external oil cooler radiator under the engine. This model also features the ETC50 bomb rack.
The S-199 was the backbone of the Czech fighter force until 1957. That makes 22 years of use from Willy Messerschmitt's basic 109 airframe design - not bad! The Hispano Aviacion HA-1112 K.1.L Tripala and Hispano Aviación HA-1112 M.1.L Buchon, the Spanish-built variants, were retired in 1955, so the Avia S-199 marks the final stop in the career of a famous aircraft type. It was replaced by the Mig-15.
The S-199 was well known for it's immensely strong torque on take-off and bad tendency to swing on landing, giving it a highly unfavorable reputation. However, an Israeli pilot stated that despite its bad ground habits, the S-199 in 1948 would climb and dive better than the P-51 Mustang and Spitfire, and could out-turn the Mustang.