Here are some images which illustrate what 'Kamm' was researching at the FKFS
Kamm's research was a follow-on addition to Walter Lay's 1933 research at the University of Michigan
which investigated Jaray's work of 1922
Everything had to do with the effect of after-body elongation and the 'shape' of the elongation with respect to drag.
My rough German translation came out as ' the aspect ratio of the aft-body,examining the length as compared to the body height,ignoring ground clearance and overall vehicle height.'