they don't and never will (at least for passenger systems) -do some maths
..try a purpose-built unpressurised freight transport (modular) system.. if you are pursuing a throw away thesis topic..
otherwise..join the alternative energy propulsion gang and put engineering into an arena with serious economic prospects..
where will the next frontier in aviation be? affordable supersonic travel, space tourism, environmentally neutral engines? pick one.. guranteed it ain't going to be flying boxcars (for a while).. economics rules.. always sad to see young engineers fencing with ether
King Patience
