There were three proposed variants; each had fuel capacity for only two target runs, after which the pilot would have been required to glide without power to a landing on under-belly skids. To survive close pursuits, the E.381 was designed with the narrowest frontal cross section possible to increase its chances of surviving shots from the front. This also forced the pilot to lie in a prone position. The cross-section was , or approximately a quarter of the cross section of the Messerschmitt Bf 109.