Built and demonstrated at Flugplatz Johnannisthal in 1911, but apparently did not fly. Later, the machine was modified, and it appears questionable whether the revision flew either. The secretive Merx Fünfdecker had “Himmelsleiter” (sky ladder) built and kept in its shed - hidden from prying eyes. When the first flight test was to take place, it turned out that the apparatus was higher than the door and could not be pulled out of the shed. Also known as the Mehrdecker-Versuchsflugzeug von J. Merx, (multiplane-experimental).