Hacker Neue

Preferences
DennisP parent
Any large fully-reusable rocket basically fits those goals, but methane might not be ideal for the second stage, if you don't intend to refuel on Mars. Hydrogen has better ISP, so your mass budget isn't so tight. It's also six times better as a coolant, so if you want to try SpaceX's original plan of using evaporative cooling in place of heavy tiles, it'll work better. Blue Origin and Stoke Space both use a methane first stage, hydrogen second stage. (Stoke Space has planned evaporative cooling from the start, Blue Origin put in a patent application for their version later.)

Then again, Musk is also big on reusing components as much as possible, so he might have opposed multiple fuels on principle.

bryanlarsen
> Hydrogen has better ISP, so your mass budget isn't so tight.

You need much larger tanks, so the mass advantage is pretty much completely eliminated. Hydrogen engines generally have much lower thrust for a given size too. Falcon9 or Starship style staging is infeasible with a hydrogen second stage. Rockets that use hydrogen for their second stage separate a lot higher and faster than Falcon9/Starship to make up for this reduced thrust. This makes Falcon/Starship style 1st stage recovery impossible.

Hydrogen would be great for a 3rd stage. If you want it to be recoverable, design a third stage that fits within the Starship enclosure. This would be a fabulous way to do small BEO missions without requiring a whole bunch of refueling.

DennisP OP
How are you distinguishing Falcon/Starship style recovery? Blue Origin actually attempted first-stage propulsive recovery with their first orbital test, with a hydrogen second stage. (It didn't work, but neither did SpaceX's first attempt.)
bryanlarsen
Yes, "impossible" was unreasonable hyperbole on my part.

Blue Glenn stages much higher and further than Falcon; it's caught much further off shore. More significantly, it doesn't have a return to launch site option like Falcon does and Starship always uses.

This item has no comments currently.