I have this book on historical VTOL aircraft (mostly 1950s - 1970s). Many reasons these concepts failed at the time could possibly be solved today (computers, FBW, composites, etc.), yet one thing seems to remain: by the time you've packed & stacked all the mechanisms, hinges, fuel, multiple engines, controls, military armour etc. etc. there may be just enough space left for one passenger and a toothbrush. I wonder what the eventual operational payload/range of the Bell concept (engineering marvel as it is, respect for that) will be. Still, looking forward to see it fly.
