Letov Š-18
Trainer aircraft
The Letov Š-18 was a Czechoslovak single-engined, two-seat biplane trainer. It was designed by Alois Smolík at Letov Kbely. The Š-18 first flew in 1925.
The aircraft was quite successful and sold well, both to private pilots and to flying clubs. Wikipedia
Manufacturer: Letov Kbely