The September 2009 edition of Model Aviation had an inset feature of the Cardboard Condor, by Ryan Livingston. The Condor has a wingspan of more than 12 feet (150.7" to be exact), and uses more than 80 square feet of 5/32" thick cardboard in its construction. Light ply and pine are used in the framework. It weighs 50.6 lbs and uses 4 O.S. .61FX 2-stroke engines. The sound of the four engines is amazing.
I assume that the name "Cardboard Condor" is a play on the "Gossamer Condor," which was the first human-powered aircraft to achieve sustained, controlled flight.
Here are a few videos of it in flight - pretty cool!