Like many amateur Polish designers in the 1930s, Adam Ścibor-Rylski was interested in simple, low cost machines. A student at the Warsaw Technical University, he began his studies with the ŚR-1, an attempt to motorize the Wrona basic, open-frame glider. Difficulties in mounting an engine in this structure led to the ŚR-2 which had the Wrona wing married to a new nacelle. By 1937 he had dropped these projects in favour of a more refined, cabin aircraft. This, the ŚR-3, was the subject of his diploma. With the encouragement of LOPP and the Silesian Gliding Workshop he received government funding. The ŚR-3 was a wooden aircraft with a highcantilever wing. The wing was a one piece structure built around a single spar and tapered in plan. It was plywood covered apart from a small fabric covered area aft of the auxiliary spar that carried the ailerons. These were unbalanced and operated differentially. It was first fitted with a Avia 4flat-four engine which failed during ground trials and was replaced by a Sarolea Albatrosflat twin with a fuel tank in the wing. Behind the engine the fuselage was a rectangular section, stressed ply skinned structure, with a rounded roof between the wing trailing edge and the tail where the fuselage narrowed strongly in profile. The ŚR-3's single-seat cockpit was under the wing leading edge and had an upward hinged, one-piece transparent cover. Its empennage was also ply covered and unbalanced, with the tailplane mounted on top of the fuselage. The fin was almost triangular and carried a full, semi-elliptical rudder which operated between the elevators. The ŚR-3 had small mainwheels mounted close to the fuselage on short, curved V-struts which had a rubber-in-compression shock absorber within the fuselage. Zbiniew Żabski flew the ŚR-3 on its first flight at the end of August 1939. Though SWS had hoped to produce the ŚR-3 in both kit and complete forms, the German invasion of Poland a few days after the first flight ended such hopes. The ŚR-3 was reportedly taken by the invaders and flown by the DortmundNaziyouth organisation.
