4 ms·

The most surprising thing to me was nixing the transpiration cooling with methane and switching back to heat shielding tiles for half of it.

mabbo 7y ago
It was such a cool idea, but I imagine it was going to be very hard to make it work.
- superkuh 7y ago
  Reusable heat shielding tiles are also very hard.
  - lukebuehler 7y ago
    Could it be easier compared to other rockets/shuttle since the space ship is made out of steel?
    - nickik 7y ago
      It makes it a bit easier because as Elon mentioned the steel structure can get much hotter without it being an issue. This makes it easier to connect the tiles directly to the ship. However still the primary problem is still to have some surface that can handle the heat without deterioration over multiple flights.
- geuis 7y ago
  Exactly. Say you land on the Moon and your ship sticks around for a few months. Micrometeorites can impact and cause minor damage to the surface cooling system. You’re baked at that point. But given the hull is stainless steel repairs are much easier. Any experienced welder can spot repair divots and holes or weld in much larger patches. No need to worry about the specially constructed parts required for evaporative cooling. Fix the hull then install replacement tiles.
SEJeff 7y ago
I don't think he said they were ablative however, so it isn't going to be like it was in the Space Shuttle where the tiles literally burned up on re-entry.
- thescriptkiddie 7y ago
  The Space Shuttle tiles were explicitly not ablative. However, there were problems with the fragility of the tiles, which meant that at least a few tiles needed to be replaced after almost every flight. There is some speculation that it would have been better to use ablative tiles, which would need to be replaced regularly but would be less susceptible to unexpected damage. https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protecti... I don't think that Elon has clarified yet whether or not the Starship tiles will be ablative, but keep in mind that Dragon currently uses a single-piece ablative heatshield which is theoretically good for several reuses.
  - nickik 7y ago
    I think its pretty clearly that the glass tiles he was talking about would not be ablative. Given how many reuses they should be able to do. Starship has the ability to dip in and out to control heating on the tile and limit the heat, keeping them within a heat corridor during reentry.
tdy721 7y ago
I really liked how he mentioned the cryogenic strength of 301 Steel, and I’m in love with KISS simplicity of it all. Transpiration specifically is out, but unmentioned is a real need to manage thermals of the craft, not just on re-entry, but on a journey to the moon. I refuse to count out some kind of neat thermal fluid tech helping out with this, mostly cause I admire the raptor engine nozzle tech! Even bad ideas can yield a bit of good. STS needed to open doors or get back down cause she would have cooked. The ISS has 2 triple sets of huge radiators!
- tdy721 7y ago
  I also want to add that EVA suits stay cool with a water sublimator! I’m sure Starship is gonna sweat somehow... xD

mabbo 7y ago

It was such a cool idea, but I imagine it was going to be very hard to make it work.

superkuh 7y ago
Reusable heat shielding tiles are also very hard.
- lukebuehler 7y ago
  Could it be easier compared to other rockets/shuttle since the space ship is made out of steel?
  - nickik 7y ago
    It makes it a bit easier because as Elon mentioned the steel structure can get much hotter without it being an issue. This makes it easier to connect the tiles directly to the ship. However still the primary problem is still to have some surface that can handle the heat without deterioration over multiple flights.
geuis 7y ago
Exactly. Say you land on the Moon and your ship sticks around for a few months. Micrometeorites can impact and cause minor damage to the surface cooling system. You’re baked at that point. But given the hull is stainless steel repairs are much easier. Any experienced welder can spot repair divots and holes or weld in much larger patches. No need to worry about the specially constructed parts required for evaporative cooling. Fix the hull then install replacement tiles.

SEJeff 7y ago

I don't think he said they were ablative however, so it isn't going to be like it was in the Space Shuttle where the tiles literally burned up on re-entry.

thescriptkiddie 7y ago
The Space Shuttle tiles were explicitly not ablative. However, there were problems with the fragility of the tiles, which meant that at least a few tiles needed to be replaced after almost every flight. There is some speculation that it would have been better to use ablative tiles, which would need to be replaced regularly but would be less susceptible to unexpected damage. https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protecti... I don't think that Elon has clarified yet whether or not the Starship tiles will be ablative, but keep in mind that Dragon currently uses a single-piece ablative heatshield which is theoretically good for several reuses.
- nickik 7y ago
  I think its pretty clearly that the glass tiles he was talking about would not be ablative. Given how many reuses they should be able to do. Starship has the ability to dip in and out to control heating on the tile and limit the heat, keeping them within a heat corridor during reentry.

tdy721 7y ago

I really liked how he mentioned the cryogenic strength of 301 Steel, and I’m in love with KISS simplicity of it all. Transpiration specifically is out, but unmentioned is a real need to manage thermals of the craft, not just on re-entry, but on a journey to the moon. I refuse to count out some kind of neat thermal fluid tech helping out with this, mostly cause I admire the raptor engine nozzle tech! Even bad ideas can yield a bit of good. STS needed to open doors or get back down cause she would have cooked. The ISS has 2 triple sets of huge radiators!

tdy721 7y ago
I also want to add that EVA suits stay cool with a water sublimator! I’m sure Starship is gonna sweat somehow... xD