Fire Control Radar FuMG 39 Würzburg Dora TD (Irja)

Six German Dora radars were purchased in Finland in 1943. Four were placed in Helsinki and two in Kotka. The radar was called “Irja” in Finland. Fire control radar revolutionized completely the shooting of heavy batteries in poor lighting and weather conditions. They significantly improved the accuracy of the barrage shooting by measuring the flight routes and altitude of the targets.

The “Irja” radars collaborated with the FuMG 401 LZ Freya “Raija” air surveillance radar in Finland so that “Raija” retrieved a target from the sky and then pointed it to “Irja”, which in turn measured the direction and distance. Values were passed on to the anti-aircraft guns, and the fire could be opened even though the target was not seen due to darkness or cloudiness. The maximum measurement distance was 25-28 km. The Irjas increased the anti-aircraft artillery alert time by 3-4 minutes and allowed the opening of fire from the extreme range of the guns. Measuring the flight path, speed and altitude of the enemy aircraft also significantly improved the accuracy of the barrage shooting.