SpaceX Starship/Super Heavy Engineering General Thread 5

[catdlr]

Ceaser G@CeaserG33
·
Interesting tank spotted at the Starfactory. What could this be used for?

https://x.com/CeaserG33/status/1967075984118861949

[OTV Booster]

With InterestedEngineers estimate of the current heatshield mass

https://forum.nasaspaceflight.com/index.php?topic=50748.4240#lastPost
msg# 4257

and his conclusion that the current V4 numbers don't add up, is it time to rethink expendable vs reusable with more mature numbers?

It seems obvious that mass delivered to LEO with ship expendable will be higher than reusable. 15t (IE's new estimated heatshield mass), 10t for the fins plus mass of landing propellant that is beyond me to calculate but I'm sure I've seen it somewhere. Anything else?

Prices do not include shipping and handling which may be substantial in the near future.

This all balances against build cost with a fudge number for opportunity costs in a fast paced refueling scenario.

My gut says unless truly fast turnaround happens quickly, early operational refueling might best depend on having a stable of expendables in hand. If the numbers are close my instinct says it might pay to use a stable of reusables and stash them on orbit until the pad traffic slacks off.

Are the numbers mature enough to even bother with this or should we wait until the first attempt to grab a ship?

[Vultur]

Expendable tankers might make sense for early refueling based missions (HLS Demo, Artemis III HLS, first Mars synod). I doubt they'd be more of a separate variant than just "leave off the heat shield" though; I don't think SpaceX will spend development resources on expendability.

[meekGee]

Expendable tankers might make sense for early refueling based missions (HLS Demo, Artemis III HLS, first Mars synod). I doubt they'd be more of a separate variant than just "leave off the heat shield" though; I don't think SpaceX will spend development resources on expendability.

Yup. They'll be expending tankers in 2026 only if they run out of choices for the window, but that's that.

[uhuznaa]

Expendable tankers might make sense for early refueling based missions (HLS Demo, Artemis III HLS, first Mars synod). I doubt they'd be more of a separate variant than just "leave off the heat shield" though; I don't think SpaceX will spend development resources on expendability.

Yup. They'll be expending tankers in 2026 only if they run out of choices for the window, but that's that.

Tankers will be just brutally sensitive to payload mass to orbit for HLS/Artemis.

They will want to arrive at reusability as soon as possible for Starlink, but fulfilling their Artemis contract will be a totally different thing.

I think it helps to view Starship as platform, not as a single craft. Horses for courses and all that.

I mean, this even starts with tankers not even needing a real payload section. The payload is propellants and this can be done with the main tanks, which again means you could get away with no nose section at all and then with no header tanks and flaps etc. you can get much more propellants up there.

And this is at first just about a quite limited amount of launches for a while (for Artemis). Maybe brute-forcing this while doing more R&D wouldn't be the worst thing to get it done. And they really need to get this done as soon as possible.

Ideally they want to get a propellant depot into orbit next year and get it filled up until the end of 2026 to test it. This will require quite a bit of R&D scrambling and cutting corners everywhere. Maybe better start with a handful of expended tankers and then continue with reusable ones later once they have nailed this down.

[Stan-1967]

Posting this for the folks on page 38, posts 740 to 757 taking about coatings that could protect the dome during hot staging.  HVOF is the technology that I think would work well, it could be done on the pad, it can be automated by robotics, however the surface prep needs to be done right, and that may be a separate problem of removing oxides  & smoothing out erosion damage.  Probably solvable.  Here's and industry link.
https://htscoatings.com/pages/hvof-spray

There are videos all over  YT for this technology.

I've seen these things in action.  Saw a C5-A landing gear hydraulic piston being built up back to OEM spec at a USAF repair facility.  it is a very fast process.   It was replacing hex chrome electroplating.

[DanClemmensen]

Posting this for the folks on page 38, posts 740 to 757 taking about coatings that could protect the dome during hot staging.  HVOF is the technology that I think would work well, it could be done on the pad, it can be automated by robotics, however the surface prep needs to be done right, and that may be a separate problem of removing oxides  & smoothing out erosion damage.  Probably solvable.  Here's and industry link.
https://htscoatings.com/pages/hvof-spray

There are videos all over  YT for this technology.

I've seen these things in action.  Saw a C5-A landing gear hydraulic piston being built up back to OEM spec at a USAF repair facility.  it is a very fast process.   It was replacing hex chrome electroplating.

Thanks! It seems that a tungsten carbide coating is technically feasible. It may be too expensive, and it may be overkill. I doubt that it would aver need to be re-applied either on the pad or otherwise, because plume impingement on the dome is unlikely to erode that coating.

It also looks like they can fly  without a coating and examine the results, and then use this technology to permanently repair any damage and also to decide if a coating can be applied selectively to certain areas or perhaps at different thicknesses.

[catdlr]

So, is this the fuel inlet/outlet for the tanker?  It would be on top of the ship, which could very well be the leading edge of the nose cone you're looking at?  The remainder of the nose cone skirt would be welded to this.

[meekGee]

So, is this the fuel inlet/outlet for the tanker?  It would be on top of the ship, which could very well be the leading edge of the nose cone you're looking at?  The remainder of the nose cone skirt would be welded to this.

Hmmm...  Some time back (1.5 years?) Musk said that tankers would look funny.

[catdlr]

So, is this the fuel inlet/outlet for the tanker?  It would be on top of the ship, which could very well be the leading edge of the nose cone you're looking at?  The remainder of the nose cone skirt would be welded to this.

Hmmm...  Some time back (1.5 years?) Musk said that tankers would look funny.

I've been informed that what I'm seeing is not part of the ship but part of the landing tank for the booster.  But yes, kissing ship would look.....awkward.

[meekGee]

So, is this the fuel inlet/outlet for the tanker?  It would be on top of the ship, which could very well be the leading edge of the nose cone you're looking at?  The remainder of the nose cone skirt would be welded to this.

Hmmm...  Some time back (1.5 years?) Musk said that tankers would look funny.

I've been informed that what I'm seeing is not part of the ship but part of the landing tank for the booster.  But yes, kissing ship would look.....awkward.

https://xkcd.com/3133/
Too much?

[catdlr]

So, is this the fuel inlet/outlet for the tanker?  It would be on top of the ship, which could very well be the leading edge of the nose cone you're looking at?  The remainder of the nose cone skirt would be welded to this.

Hmmm...  Some time back (1.5 years?) Musk said that tankers would look funny.

I've been informed that what I'm seeing is not part of the ship but part of the landing tank for the booster.  But yes, kissing ship would look.....awkward.

https://xkcd.com/3133/
Too much?

Space Ship kissing (and some reaction).   (from the upcoming video from Everyday Astro)

[catdlr]

Ceaser G@CeaserG33
·
Interesting tank spotted at the Starfactory. What could this be used for?

https://twitter.com/CeaserG33/status/1967075984118861949

https://twitter.com/ENNEPS/status/1968016055395406224

https://twitter.com/CSI_Starbase/status/1968013425398911459

https://twitter.com/VickiCocks15/status/1968039254543700099

[InterestedEngineer]

Ceaser G@CeaserG33
·
Interesting tank spotted at the Starfactory. What could this be used for?

https://twitter.com/CeaserG33/status/1967075984118861949

https://twitter.com/ENNEPS/status/1968016055395406224

https://twitter.com/CSI_Starbase/status/1968013425398911459

https://twitter.com/VickiCocks15/status/1968039254543700099

header tank?

[catdlr]

Ceaser G@CeaserG33
·
Interesting tank spotted at the Starfactory. What could this be used for?

https://twitter.com/CeaserG33/status/1967075984118861949

https://twitter.com/ENNEPS/status/1968016055395406224

https://twitter.com/CSI_Starbase/status/1968013425398911459

https://twitter.com/VickiCocks15/status/1968039254543700099

header tank?

That would be the normal though, but don't forget that this is inside the booster as well:

https://forum.nasaspaceflight.com/index.php?topic=58830.msg2700284#msg2700284

[catdlr]

Zack Golden@CSI_Starbase
Potential Version 3 ship aft section rolled out of Starfactory this morning. It appears this was a test build and will end up in the scrap yard.

This is vastly different than Version 2 and may end up with the RVac mounting points recessed into the LOX tank similar to the Grid Fins on the V3 booster.

https://twitter.com/CSI_Starbase/status/1968366819024023583

[SpaceLizard]

Zack Golden@CSI_Starbase
Potential Version 3 ship aft section rolled out of Starfactory this morning. It appears this was a test build and will end up in the scrap yard.

This is vastly different than Version 2 and may end up with the RVac mounting points recessed into the LOX tank similar to the Grid Fins on the V3 booster.

Would this give the SL Raptors more room* to gimbal by having the engine bells tiered, or would that be bad because of potential for thrust impingement on the lower SL bells by the higher Vac Raptors?
*edit to add: Specifically, more room after the loss of room that would result from changing to 6 RVacs

[Robotbeat]

Ceaser G@CeaserG33
·
Interesting tank spotted at the Starfactory. What could this be used for?

https://twitter.com/CeaserG33/status/1967075984118861949

https://twitter.com/ENNEPS/status/1968016055395406224

https://twitter.com/CSI_Starbase/status/1968013425398911459

https://twitter.com/VickiCocks15/status/1968039254543700099

header tank?

That’s what I’m thinking it might be. A big one. Starship’s header tank is insulated with MLI or similar, so it’s where you’d want propellant stored for HLS or a Mars ascent vehicle or a tanker.

[TheRadicalModerate]

That’s what I’m thinking it might be. A big one. Starship’s header tank is insulated with MLI or similar, so it’s where you’d want propellant stored for HLS or a Mars ascent vehicle or a tanker.

It can't be a header tank for HLS, unless they're willing to move the docking port to somewhere other than the nose.

Mars landers with heavy cargoes (~100t) need much, much more landing propellant, because terminal velocity is so much higher (and gets even higher still if you need to raise the flip/burn altitude to limit acceleration to 4-6gee).  So that's a possibility.

The tanker is a possibility.  If the prop to be transferred is in the payload bay and nose, it gets a nice dewar effect, just by dangling from the nose. Seems kinda structurally unpleasant and heavy, though.  But there's room in the payload bay for over 500t of boiling methalox.  My intuition has been tanker launch and RPOD with the depot wouldn't take long enough for there to be a lot of boiloff, but intuition always gets me into trouble when doing space nerdery.

[catdlr]

That’s what I’m thinking it might be. A big one. Starship’s header tank is insulated with MLI or similar, so it’s where you’d want propellant stored for HLS or a Mars ascent vehicle or a tanker.

It can't be a header tank for HLS, unless they're willing to move the docking port to somewhere other than the nose.

Mars landers with heavy cargoes (~100t) need much, much more landing propellant, because terminal velocity is so much higher (and gets even higher still if you need to raise the flip/burn altitude to limit acceleration to 4-6gee).  So that's a possibility.

The tanker is a possibility.  If the prop to be transferred is in the payload bay and nose, it gets a nice dewar effect, just by dangling from the nose. Seems kinda structurally unpleasant and heavy, though.  But there's room in the payload bay for over 500t of boiling methalox.  My intuition has been tanker launch and RPOD with the depot wouldn't take long enough for there to be a lot of boiloff, but intuition always gets me into trouble when doing space nerdery.

BTW, that tank entered MB-1 for Boosters, if it were to be installed in a Ship, it would have gone into MB02