The IS-3 was the basis of a family of high performance gliders designed by Iosif Șilimon and built in Romania in the 1950s at the URMV-3 (Rom: Uzinele de Reparatii Material Volant-3 - Glider repair and manufacture factory) factory at Brașov.
The development of the IS-3 was in four distinct phases with differences in wing position and construction as well as fuselage design.
The original glider, first flown on 19 August 1953, was built primarily of wood with a pod and boom style fuselage and high-set wings.
The tapered wings were built with plywood-covered torsion box leading edges with fabric covering aft of the main spar, incorporating spoilers for approach control and differential ailerons to reduce adverse yaw.
The IS-3c and IS-3d were drastically different in having a conventional wooden fuselage and further minor variations in wing construction and roll controls.