A 100 ton flying boat project by Dutch designer Frederik Koolhoven.
A quick research turned over only two images:
the plan

and a model

Here's an article about Koolhoven mentioning this project: http://www.alexdenouden.nl/artikelen/koolhoven.htm
And here's the model description: http://www.bel-air-models.com/models/civil/Koolhoven100TonVliegboot.asp
Does anyone have anything else on this aircraft?