Re:British technology company to 'transform' air and space t...
by Gravityloss on Wednesday December 02, 2015 @07:50AM
(#10662610)
2) And now you're carrying wings to orbit too. More dead mass that could be payload...
3) My comment was to compare liquid oxygen with liquid hydrogen which is 0.07 of water density, so you get 16 kg of oxygen for 1 kg of hydrogen for the same tank volume. Skylon uses loads of hydrogen. It's those hydrogen tanks that make it so big. Such tanks are also a lot of dead mass to carry to orbit... Also costs probably scale with dry mass, not wet mass.
3) My comment was to compare liquid oxygen with liquid hydrogen which is 0.07 of water density, so you get 16 kg of oxygen for 1 kg of hydrogen for the same tank volume. Skylon uses loads of hydrogen. It's those hydrogen tanks that make it so big. Such tanks are also a lot of dead mass to carry to orbit... Also costs probably scale with dry mass, not wet mass.