Cheers Alex!
Mráz in Post-War Czechoslovakia
In the immediate post-WW2 period, Mráz was focused on aircraft repair and parts reclamation work. The first original post-war design was the Mráz Ru-800 Trenér of late 1945. This was a 2-seat tandem basic trainer intended to satisfy a Československé vojenské letectvo (Czechoslovak Air Force) requirement. Like the competing Zlín Z-26 and Praga E-112, the prototype Ru-800 was powered by a 104 hp Walter Minor 4-III inline engine.
The Mráz Ru-800 lost that competition to the superior Zlín Z-26. But, in March 1948, Mráz took a chance on the potential pro-Russian leanings of the new Communist government in Prague. The prototype Ru-800 was taken from storage and re-engined with a 125 hp Shvetsov M-11 5-cylinder radial. The Ru-800 was also fitted with a new, fully-blown sliding canopy.
As expected, the more powerful Soviet engine improved performance but, contrary to Mráz expectations, the new government continued to favour domestic engine designs over Soviet powerplants. The Ru-800 was used by Mráz as a company hack until early 1950 were the prototype was heavy damaged when nosing over on soft ground.
(Top) Rebuilt Mráz Ru-800 with sliding canopy and Shvetsov M-11D radial, summer 1948
'Air Police' - Last Hurrah for the Mráz BM 221/Be.660
Although the last two Be.655s were destroyed at Tri Duby, a number of Argus-powered BM 221/Be.660 survived the Second World War. Refurbished by Moravan Zlínavion, twelve aircraft were assigned to the paramilitary Bezpecnost (Security) service of the federal police force. [1]
A new CzAF Aircraft Designation class - Hlídkový letoun (Patrol aircraft) - was considered for the Mráz Be.660. But, despite being operated in a border patrol capacity, the Be.660 was given the 'C' (Cvicna) for trainer designation - C 12. The Mráz C 12 served from late 1945 until early 1954.
(Bottom) Mráz C 12 in standard 1948 Bezpecnostni letectvo (Security aviation) markings - 'sfericky trojuhelnik' roundel on the tail, red nose (decorated here with police badge and 'POLICIE'), and distinctive 'OK-BYx' registration style.
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[1] The refurbished Be.660s were considered compensation for 12 Benes-Mráz Be-51B Beta-Minors ordered by the 'Air Police' in the late '30s, but still undelivered at the time of the German occupation.
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