Fendt Helicamper.
That's the answer.
And here's the story (probably a mix of fact and fiction) as compiled from various online sources...
When Libelle ceased production in 1954, some of the physical assets (probably manufacturing equipment, tools, unused vehicle parts, etc) were purchased by an as-yet unidentified company from the Friedrichshafen area of Germany, with plans to manufacture similar vehicles under its own brand. When those plans failed and the company became insolvent, Herrmann Fendt purchased three partially-assembled 'prototypes' from the insolvent company and had them brought to the Fendt compound. The trio of vehicles were eventually assembled and put up for sale, complete with Ilo engines and the '
Helicamper' script seen in the images below. The puzzle vehicle was purchased by a Fendt engineer named Karl Ummenhofer and became his means transportation to and from Fendt for the next couple of years. It's now the only one of the three 'prototype' vehicles known to still exist (albeit in a disassembled state).
There's a clear desire among online sources to label this vehicle as an abandoned project that was being developed by Fendt for production, but I found no hard evidence exists to support that theory, as Fendt didn't bother to maintain/archive any records from that period.
