Following the termination of plans for the aircraft division of the Weiss Manfred concern to build the Heinkel He 112 single-seat fighter under licence, the division's chief designer, Bela Samu, initiated work on an indigenous fighter. Designated WM-23 and named Ezustnyil (Silver Arrow), the fighter's design was launched in July 1940, and owed much to the He 112. The wing section and planform of the He 112 were retained, together with the camber-changing Fowler flaps and Heinkel's use of anhedral to reduce undercarriage height, but metal gave place to wooden construction. The plywood-covered wooden wings were mated with a welded steel-tube fuselage, also primarily plywood covered, and a WM-K-14B (licence-built Gnome-Rhone 14Kfrs Mistral Major) 14-cylinder radial engine of 1000hp. The proposed armament comprised two 7.62mm Gebaur machine guns in the wings and two synchronised 20mm MG 151 cannon in the fuselage.
The prototype WM-23 was flown for the first time in September 1941, and demonstrated good flying characteristics, but suffered intermittent aileron oscillation, and, in the late spring of 1942, the starboard aileron detached in a climb, forcing the pilot to abandon the aircraft.
Plans had meanwhile reached an advanced stage for the all-metal Ezustnyil II with a monocoque fuselage and a DB 605 engine. However, this programme was eventually discontinued with the decision that Weiss Manfred would build the Messerschmitt Bf 109G under licence.
