The long and the short of it is that an airplane can get only so big, so heavy and so fast, before it becomes structurally unsound. It's the same reason why bi-planes became museum pieces. Alerts of cracks in the superstructure of Airbus A380 superjumbo jets, currently the biggest things flying, could be a warning call that the current model -- basically just a tube with wings -- is reaching the limit of its abilities.
In response, designers, from Lockheed Martin and Boeing all the way to NASA, are going back to the drawing board and reinventing the plane, taking into account passenger capacity, structural strength, fuel efficiency, aerodynamics and all-out speed. The following is Steele Luxury Travel's traipse though some of the ideas currently being bandied about.
Take note: you may be seeing, and sitting, in one these sooner than you think.
Is it a brave, new world or what?