Increasing header widths lead conventional chopping systems with horizontal rotor and passive distribution elements to the performance limit. Only through extensive and powerintensive ancillary units, a sufficiently uniform cross distribution of the straw can be achieved. Using the principle of inertial cutting without counter blade, the development of a chopper test rig, characterized by two vertical rotors is realized in cooperation with the manufacturer Rasspe Systemtechnik. The results of extensive laboratory studies of power demand, material velocity, chopping quality and lateral distribution are presented in this article.