(Instytut Techniki Szybownictwa i Motoszybownictwa – institute of gliding and motor-gliding techniques), for a cheap ultra-light aircraft suitable for converting trained glider pilots to powered flying.

(Instytut Techniczny Lotnictwa – Technical aviation institute) and airworthiness tests without problems, also proving to have relatively good gliding performance.

The Bąk was built primarily of wood with plywood in a semi-monocoque fuselage and cantilevered single spar wooden wings, with plywood skinned leading edge torsion boxes and wing roots, mid set on the fuselage with marked dihedral.

The tail unit comprised a fin, with rudder, integral with the fuselage and a cantilever ply and fabric covered all-flying tailplane, all control surfaces were statically balanced and mounted on ball bearings.

Designer of the Bąk, Antoni Kocjan, became part of the Polish Underground resistance and was killed in the Warsaw Uprising.