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Message: <blockquote data-quote="Farnboro John" data-source="post: 1507424" data-attributes="member: 36432">I think you need to look more closely at the equations relating wingspan and muscle power to body mass and appetite.  Although ten foot plus wingspan vultures eat cows it is not at one meal and their overall weight is less than invertebrate/seed/vegetation eating bustards and swans.  In other words the increment on wingspan is likely to be immense compared to the increment on payload.29 ft is about the same as most single-engined light aircraft which require 100+ hp for a payload of 2-4 humans or 100-200kg.  A long way from carrying a car.John</blockquote>