Well, here's a big boy for its time,
and it flew...barely.
http://en.wikipedia.org/wiki/Witteman-Lewis_XNBL-1
What the article doesn't say is that the XNBL-1 had a minimum speed of 65 mph, which meant that the range between maximum and stall was only 31 mph.
Also it had the support of General Billy Mitchell, and was informally nicknamed "Mitchell's Folly".