It was a conventional, parasol-wing monoplane with fixed tailskid undercarriage, and seating for the pilot and passenger in tandem, open cockpits.

Because the cabane struts were very short, and the wing therefore placed very close to the top of the fuselage, the cockpits had the unusual arrangement of the passenger's being in front of the wing while the pilot's was behind it.

The outer half of each wing was fitted with fixed slats along the leading edge.

An initial batch of 23 machines was built for use by Czech aeroclubs.

Data from Monografie: Letov Š-39, -139, -239[1]General characteristics Performance