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 acquired the design (primarily due to media interest combined with a shortage of aircraft among aeroclubs). Stankiewicz's team worked on refining it, and on September 2, 1957, the PZL S-4 Kania-2 made its inaugural flight.