The Katyusha Zis-6 BM-13 Urss - based upon the rugged and widely used Soviet Zis-6 truck chassis
 
First seeing action in 1939, the Katyusha Rocket Launcher was a system for mounting platforms onto trucks, tanks, artillery tractors, armoured trains and even some boats in order to provide fire support for the advancing Soviet forces on the Eastern Front.
 
The BM-13 system featured rockets that were 80cm long by 13.2cm in diameter. Each one weighed 43kg - and were loaded in batches of 14-to-18 rockets per salvo. The rockets were mounted upon large steel racks of launch rails - and this entire assembly was (in the case of our model) bolted onto the back of the ubiquitous Zis-6 utility truck which was used elsewhere on the Eastern Front to shuttle troops to-and-from the frontline as well as equipment, and for many other purposes