Originally Posted by rcarsey
....Anyone not familiar with [motorgliders], they are basically airplanes with a wing loading of less than .6 lbs/sqft....
Close but not exactly. It's not wing loading based upon area, as the term customarily means, but weight divided by span squared.
For example, at Van's RV-3B gross weight of 1,100 pounds, it would need a wingspan of at least 42.12 feet to be a motorglider.
FAA's actual criteria is 3.0 kg/m^2, or (their conversion) .62 lb/ft^2. It's in AC 21.17-2A, if you're interested.