The Mráz M.1 Sokol (English: "Falcon") was a light aircraft built in Czechoslovakia in the years following the end of the Second World War. Designed in secret by Zdeněk Rublič at the Beneš-Mráz factory during the German occupation, the type was put into production in 1946. The Sokol was a conventional, low-wing monoplane that took the pre-war Beneš-Mráz Bibi as its starting point. Two seats were provided side-by-side in an enclosed cabin, and the main units of the tailwheel undercarriage were retractable. Construction throughout was of wood. The prototype, designated the M.1/1 and registered as OK-ZHA, first flew on 9 March 1946. After testing, the prototype was redesignated the M.1A, as the type entered production. A re-engined two-seater was built designated the M.1B with a 105 hp (78 kW) ZLAS Toma 4 engine, flying for the first time on 19 May 1946 but no more M.1Bs were built. Instead, the M.1A was modified by adding a third seat in the rear, becoming the M.1C and first flying on 16 February 1947. The M.1C became the main production variant with 183 aircraft built. In 1948 the M.1C was further developed as the M.1D with an enlarged single-piece canopy and a revised rudder. The M.1D first flew on 4 October 1948 and 104 were built. One M.1D was fitted with locally produced floats and re-designated the M.1E, it first flew in September 1949. A minor variant was the Para-Sokol which was fitted with rearward sliding canopy to allow parachutists to leave the aircraft. Around 287 aircraft were built but the deterioration of the Urea-based glue used caused many examples to be condemned in the early 1960s and withdrawn from use. Nineteen Sokols were recorded as still being registered in 2013 with only a few still flyable. Variants M-1A – original two-seat version with Walter Minor engine M-1B – similar to M-1A but with ZLAS Toma 4 engine (1 built) M-1C – revised version, with longer fuselage and third seat, and swept leading edges on wing (183 built) M-1D – similar to M-1C with new, single-piece canopy and larger rear windows (104 built) M-1E – similar to M-1D but equipped with pontoons (at least 1 built)