Quote from: Robotbeat on 12/16/2016 01:52 pmProblem with your analysis is you assume same dry mass for both methane and hydrogen. Very poor assumption. Not really. The same design for hydrogen could store either oxygen or methane easily (but the inverse not so much) and insulate it well; the engine to burn the fuel is the real issue. Also it is now known water is fairly common on Mars; both hydrogen and methane could be manufactured from it. Since both propellants can be obtained using water, it is reasonably possible either could be utilized.
Problem with your analysis is you assume same dry mass for both methane and hydrogen. Very poor assumption.