Complex sentence: The AVIC AG600, code named Kunlong (鲲龙), also known as TA-600, is the largest amphibious aircraft presently manufactured, though in the 1940's and 1950's there were larger amphibious aircraft built including the Martin JRM Mars.
Split into simpler sentences: The AVIC AG600, code named Kunlong (鲲龙), also known as TA-600, is the largest amphibious aircraft presently manufactured. Note though in the 1940s and 1950s there were larger amphibious aircraft built including the Martin JRM Mars.