Sorry, I didn't realize the why was directed at me. I had read a few days ago that a plane's weight could not exceed 1/4 of the static thrust it produced or it would not fly, and that a 1 to 1 ratio of thrust to weight would allow you to prop stall. I am playing around with some foam and stuff, building a plane for ****s and giggles, and wanted to know how heavy it could be and still fly.