Quote from: pmenstrom on 01/22/2019 10:05 am"Moreso than any other single part, the most confusing aspect of Starhopper has to be the apparent condition of its steel tank domes, distinctly covered with a patina of impurities like rust, dirt, dust, and grime." https://www.teslarati.com/spacex-starship-hopper-tank-bulkhead-installation-launch-landing-pad-progress/Could they be planning to use cryogenic bladders inside the rough, dirty steel tanks?Or... just clean it?
"Moreso than any other single part, the most confusing aspect of Starhopper has to be the apparent condition of its steel tank domes, distinctly covered with a patina of impurities like rust, dirt, dust, and grime." https://www.teslarati.com/spacex-starship-hopper-tank-bulkhead-installation-launch-landing-pad-progress/Could they be planning to use cryogenic bladders inside the rough, dirty steel tanks?
The problem is if what we're seeing is the common bulkhead (i.e. lower dome of the LOX tank), and assuming the top dome goes above the triangular support beams, the LOX tank volume would be too large. If the tank height is 2.2m (0.8m between top of the beam to top edge of the hopper), dome volume 92m^3 (truncated cone, h=3, R=4.5, r=1.5 (3m top hole)), this gives total LOX volume of 324m^3, or 369t of LOX. Total propellant load would be 471t, that just leaves 29t of structure mass if we assume liftoff T/W of 1.2.
Quote from: jpo234 on 01/22/2019 10:07 amQuote from: pmenstrom on 01/22/2019 10:05 am"Moreso than any other single part, the most confusing aspect of Starhopper has to be the apparent condition of its steel tank domes, distinctly covered with a patina of impurities like rust, dirt, dust, and grime." https://www.teslarati.com/spacex-starship-hopper-tank-bulkhead-installation-launch-landing-pad-progress/Could they be planning to use cryogenic bladders inside the rough, dirty steel tanks?Cool tool, but very expensive. But I suspect that would not be a problem for SpaceX.Or... just clean it?of course this video says the laser takes off the oxide layer, which you might want for a LOX tank, but I assume that commercial steel LOX tanks have a coating to prevent oxidation so they would apply something similar.
Quote from: pmenstrom on 01/22/2019 10:05 am"Moreso than any other single part, the most confusing aspect of Starhopper has to be the apparent condition of its steel tank domes, distinctly covered with a patina of impurities like rust, dirt, dust, and grime." https://www.teslarati.com/spacex-starship-hopper-tank-bulkhead-installation-launch-landing-pad-progress/Could they be planning to use cryogenic bladders inside the rough, dirty steel tanks?Cool tool, but very expensive. But I suspect that would not be a problem for SpaceX.Or... just clean it?
Quote from: pmenstrom on 01/22/2019 10:05 am"Moreso than any other single part, the most confusing aspect of Starhopper has to be the apparent condition of its steel tank domes, distinctly covered with a patina of impurities like rust, dirt, dust, and grime." https://www.teslarati.com/spacex-starship-hopper-tank-bulkhead-installation-launch-landing-pad-progress/Could they be planning to use cryogenic bladders inside the rough, dirty steel tanks?It’s almost as if they are deliberately trying to shake off the current aerospace mantra that everything must be assembled in an expensive clean room facility. I don't think it does. If they manage it correctly it should not be a problem. No doubt there is some dirt and grime on it but a jet wash would remove most of that and rust is not a problem unless it is going to come loose.
Elon has stated that the smooth-skinned orbital prototype of Starship will be complete by June and will fly later this year.Do we have any clue where it's being built?Is it somewhere on the Texas Gulf Coast, like Port of Brownsville?Hard to imagine something so big could be built without the space community not knowing where......
any ideas on helium tanks? will they use COPV? or could a smaller SS tank fit inside these? wasnt there something like that on one of the original diagrams?
Quote from: dorkmo on 01/22/2019 11:42 pmany ideas on helium tanks? will they use COPV? or could a smaller SS tank fit inside these? wasnt there something like that on one of the original diagrams?They don't need helium. Autogenous pressurization of the tanks by vaporizing LOX/Methane.
Quote from: Jcc on 01/22/2019 11:45 pmQuote from: dorkmo on 01/22/2019 11:42 pmany ideas on helium tanks? will they use COPV? or could a smaller SS tank fit inside these? wasnt there something like that on one of the original diagrams?They don't need helium. Autogenous pressurization of the tanks by vaporizing LOX/Methane.True that it may, I’m not sure it’s 100% correct to say they won’t need helium. I think non- engine derived high pressure gas may still be required from time to time. For example, doesn’t the Raptor still need something to spin up the turbos during startup?
Where they're going they won't have helium.Matthew
Is it possible that the leg support triangle is removed when the top dome is welded in ?Would the dome be strong enough ?
True that it may, I’m not sure it’s 100% correct to say they won’t need helium. I think non- engine derived high pressure gas may still be required from time to time. For example, doesn’t the Raptor still need something to spin up the turbos during startup?
Mars is the main reason they cannot use helium.
Quote from: Johnnyhinbos on 01/23/2019 01:35 amTrue that it may, I’m not sure it’s 100% correct to say they won’t need helium. I think non- engine derived high pressure gas may still be required from time to time. For example, doesn’t the Raptor still need something to spin up the turbos during startup?Musk himself has stated before that they do not want to use helium. They plan to use autogenous pressurization because Musk severely dislikes helium for pressurization. Given the problems they have had with helium tanks, I can't blame him.