In 1956, the design was taken over by WSK-Mielec factory (partly due to an interest of the press, combined with shortages of aircraft in aero clubs). It was developed and improved by Stankiewicz's team and on 2 September 1957, a new prototype, the PZL S-4 Kania-2, was flown.
In 1956, WSK-Mielec factory took over the design (mainly because of media interest coupled with limited availability of aircraft among aeroclubs). Stankiewicz's team further developed and improved it, culminating in the PZL S-4 Kania-2 prototype's first flight on September 2, 1957.