There is NO size limit, the catch, NO Propellers, NO ENGINES to propel yourself backwards meaning no brake type of engines. you CAN have air brakes, but ONLY 10 airbrakes. and it has to be able to take off AND land on the BIG aircraft carrier, NOT the USS Tiny, but the other one that travels Island to Island. oh, and NO VTOL capabilities. thats cheating. you must at least video tape your plane doing it as proof. the top two winners get shoutouts from my page.