Development of an SPG on the chassis of the Pz.Kpfw. VIB Tiger II started in 1942. The project called for designing a common self-propelled gun carriage for the 17 cm Kanone 72 gun and 21 cm Mörser 18/1 howitzer. The concept of the SPG allowed the use of artillery systems from both the carriage and the ground. Work on building an experimental prototype began in 1945.
Time for the successive autoreloading of each shell into the magazine.
Characteristics are specified for Siege mode.
Characteristics are specified for Rapid mode.
Characteristics are specified for vehicles with crews trained to 100%.