The E-45 was an equal span, single bay biplane with wings of slight stagger and no sweep.
This was aluminium skinned around the engine, upper decking and extreme tail, and fabric covered over plywood elsewhere.
The control surfaces were horn balanced, and the tail plane incidence could be trimmed in flight.
[2] Two fixed 7.92 mm (0.312 in) calibre Type 30[3] machine guns were mounted in the upper cowling, firing through the propeller.
No more were built and the sole example of the Praga E-45 eventually received a civil registration, OK-ERR in April 1938, after which nothing was heard of it.