Author Topic: Should Starship have a third stage for single-launch high-energy trajectories?  (Read 70546 times)

Offline Zed_Noir

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Another thing some people don't realize.  SpaceX can send a tanker into orbit.  Then, with supply tankers fill it up.  Then when a mission beyond earth orbit or GSO is needed, a Starship can refuel with only one docking and go on its way with whatever payload it carries.  To the moon, Mars, or beyond.  Docking multiple times with a high cost payload or humans probably will not be done because of using a tanker for a fuel depot, that can be filled anytime with tanker Starships.  Then only one docking will be needed.

Basically the Lunar Starship propellant refilling scheme with the depot tanker (aka "The Shelby").

Offline DanClemmensen

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Another thing some people don't realize.  SpaceX can send a tanker into orbit.  Then, with supply tankers fill it up.  Then when a mission beyond earth orbit or GSO is needed, a Starship can refuel with only one docking and go on its way with whatever payload it carries.  To the moon, Mars, or beyond.  Docking multiple times with a high cost payload or humans probably will not be done because of using a tanker for a fuel depot, that can be filled anytime with tanker Starships.  Then only one docking will be needed.
This is of course the mission plan for Starship HLS, so it's not only possible, but SpaceX is basically contractually obligated to implement this by 2024 for the HLS uncrewed demo mission. One caveat, the depot for the HLS contract appears to be a separate Starship variant, not a tanker. the depot will never return to Earth, so the mass of the TPS, flight control surfaces, and structural strengthening for descent through the atmosphere is saved and the tanks can therefore be bigger. Thus teh HLS contract calls for a total of three Starship variants: HLS, tanker, and deport.

There is no evidence (yet) that a tanker will be able to refill a standard Starship or another tanker. SpaceX may choose to use the tanker only to fill the depot, and require Starships that need refueling to use the depot. Eventually they  will tell us.

Offline BarryKirk

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What about the possibility of a Starship third stage that would replace the payload section.

Not sure how that would affect the ability of the current upper stage to re-enter properly.  It might require a specially redesigned upper stage.

I'm thinking of several use categories.

1) That third stage could be for a crew module, call it a super dragon, that would provide starship with a crew escape capability.  It might be easier to man rate a capsule for re-entry then a current starship upper stage.

2) That third stage could be for relatively lightweight, but large cargo, essentially a massive fairing, say 15 meter diameter.


Offline steveleach

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What about the possibility of a Starship third stage that would replace the payload section.

Not sure how that would affect the ability of the current upper stage to re-enter properly.  It might require a specially redesigned upper stage.

I'm thinking of several use categories.

1) That third stage could be for a crew module, call it a super dragon, that would provide starship with a crew escape capability.  It might be easier to man rate a capsule for re-entry then a current starship upper stage.

2) That third stage could be for relatively lightweight, but large cargo, essentially a massive fairing, say 15 meter diameter.
Discussed previously at https://forum.nasaspaceflight.com/index.php?topic=54077.40

[zubenelgenubi: Threads merged.]
« Last Edit: 11/15/2023 04:21 pm by zubenelgenubi »

Offline BarryKirk

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What about the possibility of a Starship third stage that would replace the payload section.

Not sure how that would affect the ability of the current upper stage to re-enter properly.  It might require a specially redesigned upper stage.

I'm thinking of several use categories.

1) That third stage could be for a crew module, call it a super dragon, that would provide starship with a crew escape capability.  It might be easier to man rate a capsule for re-entry then a current starship upper stage.

2) That third stage could be for relatively lightweight, but large cargo, essentially a massive fairing, say 15 meter diameter.
Discussed previously at https://forum.nasaspaceflight.com/index.php?topic=54077.40

Thank you.  I was unaware of that thread.

Offline Brigantine

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I'm thinking of several use categories.

1) That third stage could be for a crew module, call it a super dragon, that would provide starship with a crew escape capability.  It might be easier to man rate a capsule for re-entry then a current starship upper stage.

2) That third stage could be for relatively lightweight, but large cargo, essentially a massive fairing, say 15 meter diameter.
re 2) - that sounds like a custom expendable Starship, not a 3rd stage. Starship can't EDL without a nosecone (I presume), and you don't need a 3rd stage to reach LEO. It also sounds very aerodynamically awkward through MaxQ to have a 15m fairing and elonerons all up top of the stack...
People have also mentioned elsewhere there are no facilities for preparing/encapsulating a 15m fairing - though if there's a client with deep enough pockets, it can happen.
(besides, the cost of building & expending 1 Starship will be low compared to designing a custom fairing stage let alone a custom re-usable EDL stage, and then what can you re-use it for?)

2.1) IIRC Elon has previously discussed 300t payloads on expendable Starships - No header tanks, fins, heat tiles etc. - though still done with just 2 stages. This is also the starting point for Launching Orion on SH with Disposable S2 to replace SLS.

3) Getting smaller payloads to high energy destinations with an "Expendable Upper Stage" that doesn't weigh 80t dry

3.1) same as 3), but even smaller scale, using re-usable Starships with a "3rd stage" in the payload bay.

If LEO cargo Starships are essentially bulk freight, then the "third stage" would be a new off-the-shelf methalox kick stage - launched empty in the cargo bay (vertical? on a cradle?), with a claim on XX tonnes of fuel in the tanks of that same SS, to be transferred once on orbit.

It never sees any aero forces, and can be designed on that basis. For e.g. 40 tonnes of methalox and with 1 RVac, but can be under-filled or have multiple units concatenated together based on requirements. (extra tanks without an RVac)

Or go to the trouble of making it re-usable (back to LEO) and call it a methalox space tug. Handy when your LEO bulk freight node isn't in the exact same orbit as the rideshare payload's final destination.
(going to a slightly different inclination, MEO, or GEO instead of GTO...)
At which point you basically have 2nd hand propulsion services already in orbit you can buy & expend

Have smaller methalox kick stages / tugs been previously discussed?

Discussed previously at https://forum.nasaspaceflight.com/index.php?topic=54077.40
Other related threads:
- Abort options for Starship and Starship/SuperHeavy
- Starship Expendable Upper Stage? also mentioning e.g. long duration Centaur V re-usable by hydrolox refueling in LEO
- Launching Orion on SH with Disposable S2
- Blue Ring project - space tug (hydrolox? nuclear?)
« Last Edit: 11/14/2023 10:33 pm by Brigantine »

Offline TomH

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Getting the Starship to orbit and then re-propping gives you a far more capable EDS than a third stage.

Offline Cherokee43v6

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Once again, a question posed that fails to understand what SpaceX is doing.

What is more valuable in the long term?  Doing what has always been done or trying something new that, if successful and once perfected completely changes the game?

A large group of people complained that SpaceX wasn't designing the Falcon9 on the bleeding edge of materials, weight and technology... they called it a 1960's rocket...  THEN SPACEX LANDED THE THING AND REUSED IT!!!

They're complaining that the Superheavy/Starship stack uses Methalox instead of Hydrolox... But the whole point there is long-term storage of the propellant and local in-situ production at remote destinations... Again, looking to long term benefits.

Orbital refueling is the future.  Starship's job is to prove that.

Besides, if they make the thing any taller, you can walk off the top into orbit!



edit: clarity
« Last Edit: 11/16/2023 02:50 am by Cherokee43v6 »
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Offline Brigantine

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Somewhat relevant: Landspace, who recently put payloads in LEO on a methalox LV, are now going Falcon-9-size.

So the ZQ-3 will have an upper stage that uses 100 tons ish of methalox. It would take approximately... *checks notes* one Starship Tanker to refill it & send to a high-energy trajectory with its F9→LEO class payload. Think 15+ tons direct to Jupiter.

assuming it adopts Starship-compatible docking, at least as a custom modification for 1 mission, instead of making a custom mod to Starship

[EDIT: Clarified that "100 tons" is propellant capacity, not payload capacity. Also note they claim 3,500 m/s ISP]
« Last Edit: 12/11/2023 06:43 am by Brigantine »

Offline r8ix

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Somewhat relevant: Landspace, who recently put payloads in LEO on a methalox LV, are now going Falcon-9-size.

So the ZQ-3 will have a 100 ton ish capacity methalox upper stage. It would take approximately... *checks notes* one Starship Tanker to refill it & send to a high-energy trajectory with its F9→LEO class payload. Think 15+ tons direct to Jupiter.

assuming it adopts Starship-compatible docking, at least as a custom modification for 1 mission, instead of making a custom mod to Starship

It's 20t expendable, est. 16.5 reusable.

Offline catdlr

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This might work.   ;)

There are 4 SS variants (3 different types) 4 hot staging rings, in this model.  Not!

https://twitter.com/emilromano7/status/1732777085704323360
« Last Edit: 12/11/2023 06:36 am by catdlr »
Tony De La Rosa, ...I'm no Feline Dealer!! I move mountains.  but I'm better known for "I think it's highly sexual." Japanese to English Translation.

Offline Twark_Main

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This might work.   ;)

There are 4 SS variants (3 different types) 4 hot stagging rings, in this model.

...

It's glorious!!   :o :o

However by my count I see one SS variant (the standard unmodified upper stage), two SH variants, and 1 hot staging ring. The part below the hot staging ring is just emulating the texture of the external stabilizing stringers.

I'm pretty sure "hot stagging" is some unspeakable British activity...    8)
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline catdlr

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This might work.   ;)

There are 4 SS variants (3 different types) 4 hot stagging rings, in this model.

...

It's glorious!!   :o :o

However by my count I see one SS variant (the standard unmodified upper stage), two SH variants, and 1 hot staging ring. The part below the hot staging ring is just emulating the texture of the external stabilizing stringers.

I'm pretty sure "hot stagging" is some unspeakable British activity...    8)

Twark_Main
Yeah, I got over-excited (on both accounts), thanks that was funny.  Could you imagine the tower height that would be needed for that LV if it was what I thought?

Anyway, here is the same creator modeling the current LV
« Last Edit: 12/11/2023 06:32 am by catdlr »
Tony De La Rosa, ...I'm no Feline Dealer!! I move mountains.  but I'm better known for "I think it's highly sexual." Japanese to English Translation.

Offline Nomadd

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This might work.   ;)

There are 4 SS variants (3 different types) 4 hot staging rings, in this model.  Not!

https://twitter.com/emilromano7/status/1732777085704323360
Does it have crossfeed?
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline catdlr

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This might work.   ;)

There are 4 SS variants (3 different types) 4 hot staging rings, in this model.  Not!

https://twitter.com/emilromano7/status/1732777085704323360
Does it have crossfeed?

Of course, it's constructed entirely of LEGOs. Yes, Mildred, you can build a rocket out of LEGO's.    ;)  ;D

Or can't you:  https://forum.nasaspaceflight.com/index.php?topic=43328.msg1701146#msg1701146
« Last Edit: 12/11/2023 09:46 am by catdlr »
Tony De La Rosa, ...I'm no Feline Dealer!! I move mountains.  but I'm better known for "I think it's highly sexual." Japanese to English Translation.

 

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