The Praga E-40 was a single engine, two seat, biplane basic trainer, built in Czechoslovakia in the mid-1930s.

A pair of vertical N-form struts joined the wing centre section to the upper fuselage.

The fixed tail surfaces were wood framed and plywood covered; the tailplane was strut braced from below.

The E-40 was powered by a four-cylinder 63/71 kW (85/95 hp) Walter Minor air-cooled, inverted piston engine driving a two-blade propeller.

It had a split type main undercarriage with wheels on V-form legs mounted just forward of the wing leading edge.