Dornier 17 Z Kauz I & II and Spanner Anlage

After Dornier 17 bomber production ended in 1940, some Z models were modified with a solid nose, effectively ‘grafted’ from the Junkers 88 C and fitted with a single 20 mm MG FF cannon and three MG 17 machine guns for use in the night fighter role.

Three prototypes were converted from existing Z-series airframes to the Dornier 17 Z-7 Kauz I (‘screech-owl’) configuration. The standard Z-7 was fitted with Bramo 323 P-1 radial engines and had a crew of three. In comparison to the bomber version, the fuel load arrangement was altered by subdividing it into cells; two cells were in the wings, with a capacity of 770 litres (154 imperial gallons) each and a third cell placed in the bomb bay in the fuselage with a capacity of 895 litres (179 imperial gallons). The oxygen supply for the three-man crew was reduced because intercepts at high altitudes were not anticipated. Add-on armour of steel plating was bolted to the nose bulkhead to protect the crew against frontal fire. Originally, it was planned to completely armour the crew compartment.

Later, the design was further modified to the Do 17 Z-10 Kauz II, with the solid nose now also containing an infrared searchlight for the Spanner Anlage infrared detection system as seen in the accompanying photograph. The infrared lamp in the nose was used to illuminate the target, while the display unit in the windscreen made the reflection visible to the pilot. The Dornier Z-10 was armed with four MG 17 machine guns grouped above the IR light and two 20 mm MG FF in the lower nose. The crew could reload the drum magazines for the cannons internally. Defensive gun positions included the B and C stand, each equipped with a single MG 15.

Only ten Kauz II designs were converted from existing Z-series airframes with the Spanner Anlage system ultimately proving to be essentially useless.