At least four different designs were considered, this is the 15 cm Gerät 50 with on mount autoloader refilled manually in-between bursts, of the others less is known as they were later and didn't get as far. With a weapon like this a totally fixed position makes a bit of sense, for 128mm, you could still tow that if you wanted in two pieces and railroad cars provided ample mobility for defending industrial centers. Certainly more mobility than a gun on a tower! The 15cm guns weighed more than Panzer IV tanks and could never have been more than 're-locatable'. 15 cm Flak Gerät 50 15 cm Flak Gerät 55 15 cm Flak Gerät 60 15 cm Flak Gerät 60F German title: Gerät 50 Calibre: 149.1 mm Barrel length: 7753 (L/52) Rifled barrel length: 6113 mm Shipping Weight: 44,600 kg (shipment in 4 parts) Weight own weapons (without chassis): 32 000 kg Bearing: -1 ° 30 '+90 ° Traverse: 360 ° Muzzle velocity: 890 m / s Missile Weight: 40 kg Range: 16,300 m (height) Rate of fire: 10 rounds per minute Manufacturer: Krupp AG, Essen The design was commissioned as a backup project Rheinmetall (Gerät 55) in 1936. Work was halted in January 1940.