I'm wrestling with the question of dragon flight and whether it would be possible/feasible. I've read the book "the Flight of Dragons" Peter Dickinson, Harper & row, 1979. Dickinson argues that for a full sized dragon, which he puts at 90 feet long, six feet wide and 20,000 pounds, a dragon would need a wingspan of 600 feet (16,000 square feet) which is (according to him) aerodynamically impossible. Dickinson theorizes that if dragons existed they would have flown by biologically produced, lighter than air gasses (like a zeppelin). I want to know how i could calculate the wing span/area required for a 20ft 200lb dragon without gasses. OR what would be the maximum feasible dimensions for a purely wing powered dragon?