Szpak-2 and Szpak-3 remained in single units, but in 1947 there was designed the LWD Szpak-4, which was the first Polish post-war plane built in series - a short series of 10 was manufactured in PZL-Mielec.
The single Szpak-2 and Szpak-3 remained separate entities, but in 1947, the LWD Szpak-4 design was created, representing the first Polish post-war aircraft produced on a larger scale - only 10 units were manufactured at PZL-Mielec.