The operation of the Iskra in the Polish military aviation revealed the need for further improvements and better production quality. In 1966, work began on developing a combat trainer aircraft called the Iskra 100. It featured new radio equipment for communications and radio navigation.
Disc brakes were incorporated into the landing gear, facilitating taxiing, takeoff and landing. Its gun armament remained unchanged. Four pylons with hardpoints for additional ordnance were mounted under the wings, which could include unguided rocket launchers, 50 kg bombs and gun pods with machine guns.
Serial production under the name Iskra bis B was carried out between 1969 and 1974, with 134 aircraft built.
| Wingspan | 10.06 m |
| Length | 11.15 m |
| Takeoff weight | 3862 kg |
| Maximum speed | 720 km/h |
| Ceiling | 11000 m |
| Range | 1200 km |
| Armament | 23 mm cannon, capability to carry 50 kg bombs, machine gun pods and unguided rocket launchers on four underwing hardpoints |
| Engine | SO-1 with 9.8 kN (1000 kG) thrust |
