Author Topic: Starship performance expendable mode in LEO with over 200 T fully reusable mode?  (Read 9063 times)

Offline MarkBogdani

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Hello,

Recently was the news for thrust increase by 20% for Starship, to have a fully reusable mode payload mass over 200 T in a useful orbit. What would be the new perforrmance in expendable mode in LEO (expendable Super Heavy only) and fully expendable mode (expendable Super Heavy and Starship if would have been used for cargo configuration) with this improvements ?
« Last Edit: 07/23/2023 12:44 am by MarkBogdani »

Offline DigitalMan

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Offline MarkBogdani

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Offline DigitalMan

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i seem to recall that. Here it is:

https://forum.nasaspaceflight.com/index.php?topic=47352.msg2503801#msg2503801

This link does not answer to the question

I was answering the question that catdlr posted, asking where you saw that. He seems to have deleted his post.

Offline catdlr

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i seem to recall that. Here it is:

https://forum.nasaspaceflight.com/index.php?topic=47352.msg2503801#msg2503801

This link does not answer to the question

I was answering the question that catdlr posted, asking where you saw that. He seems to have deleted his post.

Boy,  I'll ask the question again. to MarkBogdani:  Please provide a source for your statement.
(the initial sentence, not the question you posed)
(Digital Man provided an answer)
(I deleted my post to clean the thread).
« Last Edit: 07/23/2023 04:26 am by catdlr »
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Offline MarkBogdani

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i seem to recall that. Here it is:

https://forum.nasaspaceflight.com/index.php?topic=47352.msg2503801#msg2503801

This link does not answer to the question

I was answering the question that catdlr posted, asking where you saw that. He seems to have deleted his post.

Boy,  I'll ask the question again. to MarkBogdani:  Please provide a source for your statement.
(the initial sentence, not the question you posed)
(Digital Man provided an answer)
(I deleted my post to clean the thread).

Its ok, the main thing is what are the numbers for expendable mode. I am not finding something about them. I see many assumptions and speculations on other topics, but for these not finding something. It seems difficult to answer since there is no answer including my question in this forum. I don't have the neccessary qualifications or knowledge to make calculations for space rocketry such as delta-v. Maybe it is neccessary additional data from SpaceX provided to make calculations including thrust and specific impulse movement from sea level to vacumm, during the flight and additional data for the rocket. However still waiting for some answer until SpaceX provides this answr, if it will sometimes in the future for the rocket performance in expendable mode

Offline aero

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I suspect that if it seems necessary to expend rockets, Elon will quickly start on a bigger, reusable rocket.
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Online DanClemmensen

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I suspect that if it seems necessary to expend rockets, Elon will quickly start on a bigger, reusable rocket.
I think any fully-reusable system will also be able to launch heavier payloads in an expendable mode. But if the number of payloads than need the expendable mode is tiny, it is cost-effective to just expend instead of designing and building a new system. Also I think that the relative cost of dividing a large payload into smaller payloads decreases as the size of the payload increases.

Offline meekGee

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I suspect that if it seems necessary to expend rockets, Elon will quickly start on a bigger, reusable rocket.
Remains to be seen.
Because of the very long roundtrip time, the financial benefits of reusability don't only get reduced, they get deferred.

Unlike a tanker, a Mars ship will only be used 10 times or so, and the financial benefit deferred by 20 years.

Also, faster trips reduce payload and increase fuel requirements, resulting in more tanker flights.

Since stainless ships are so cheap, it really may make sense to not bother returning them. 

The unequivocal statements about reuse and super-fast return trajectories predate the transition to stainless IIRC.
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Offline MarkBogdani

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I suspect that if it seems necessary to expend rockets, Elon will quickly start on a bigger, reusable rocket.
Remains to be seen.
Because of the very long roundtrip time, the financial benefits of reusability don't only get reduced, they get deferred.

Unlike a tanker, a Mars ship will only be used 10 times or so, and the financial benefit deferred by 20 years.

Also, faster trips reduce payload and increase fuel requirements, resulting in more tanker flights.

Since stainless ships are so cheap, it really may make sense to not bother returning them. 

The unequivocal statements about reuse and super-fast return trajectories predate the transition to stainless IIRC.

The main point and the reason asking this question is to know what can do Starship compared to other heavy rockets. Although is useful or not the expendable version, would be fair to compare the expendable mode payload mass of Starship compared to other heavy rockets from all countries that have shown mainly expendable payload mass data. Starship is projected from the begining to be reusable however is not right to compare to other rockets that are expendable because we don't know really what can do each of rockets

If we do this we can understand better what can do Starship and what improvements has its technology

Offline Nomadd

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 Seems like Mark is asking a very good question, and one that users, particularly government agencies, are going to ask.
 Even is a Starship/booster costs $100 million to build, that's chicken feed to anyone thinking of putting a 300 ton payload up.
 Time is probably more important than money for SpaceX. In the early days, they might not want to sacrifice ships if it's going to set their schedule back.
 They may not design the ship to handle more than fully recoverable payload, and render the question moot.
« Last Edit: 07/27/2023 09:22 am by Nomadd »
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Offline meekGee

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Seems like Mark is asking a very good question, and one that users, particularly government agencies, are going to ask.
 Even is a Starship/booster costs $100 million to build, that's chicken feed to anyone thinking of putting a 300 ton payload up.
 Time is probably more important than money for SpaceX. In the early days, they might not want to sacrifice ships if it's going to set their schedule back.
 They may not design the ship to handle more than fully recoverable payload, and render the question moot.
Sure if someone wants a 300 ton payload, they'll expend a ship.  They don't seem to be attached to them anyway...

But when comparing with other rockets, we should consider the default reusable mode with a puny 150 ton payload, and then compare price, availability, responsiveness...  Where reusability will help them win the comparison.
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Online oldAtlas_Eguy

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It is all about what makes economic sense. Once production rates climb up for SS. The cost of manufacture for a Cargo SS can get as low as just above $50M each. For going to LEO an expendable SS usage would be a very rare exception because each flight costs would be down in the ~$20M or less values. Making the cost of using an expendable per kg to be more expensive.

But that is not so for Lunar or Mars. That is because the launch costs to Lunar or Mars can be >$180M per delivery of cargo. Such that the value of the vehicle itself at those locations is worth more or very close to the value of usable material when using the cost of sending per kg similar material. The "expended" SS at those locations makes useful pre made pressure vessels for use to store many different liquids and gasses. They can also be used as habitat space with some conversion by adding equipment into them. So that it would make sense for doing many one way cargo flights to the Moon or Mars from an economic standpoint.

But we are talking about when both Moon and Mars has the infrastructure to make use of the vehicles.

The exceptions in the short term right now and into the near future (next almost a decade) to the basic economic considerations is for an integral cargo that is so heavy without prohibitively sending it in pieces that it makes sense to do an expendable SS flight to the destination.

Offline Blackjax

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Aside from propellent and water, what payloads are people thinking are dense enough to consume 250-300 ton lift capacity without hitting volume constraints

Online DanClemmensen

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It is all about what makes economic sense. Once production rates climb up for SS. The cost of manufacture for a Cargo SS can get as low as just above $50M each. For going to LEO an expendable SS usage would be a very rare exception because each flight costs would be down in the ~$20M or less values. Making the cost of using an expendable per kg to be more expensive.

But that is not so for Lunar or Mars. That is because the launch costs to Lunar or Mars can be >$180M per delivery of cargo. Such that the value of the vehicle itself at those locations is worth more or very close to the value of usable material when using the cost of sending per kg similar material. The "expended" SS at those locations makes useful pre made pressure vessels for use to store many different liquids and gasses. They can also be used as habitat space with some conversion by adding equipment into them. So that it would make sense for doing many one way cargo flights to the Moon or Mars from an economic standpoint.

But we are talking about when both Moon and Mars has the infrastructure to make use of the vehicles.

The exceptions in the short term right now and into the near future (next almost a decade) to the basic economic considerations is for an integral cargo that is so heavy without prohibitively sending it in pieces that it makes sense to do an expendable SS flight to the destination.
The other case is when the SS becomes part of the payload, as in an SS-based station in LEO or other locations. It's not expended, it's not reusable as an LV, but including its contents it's a lot heavier than 300 T.

Online DanClemmensen

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Aside from propellent and water, what payloads are people thinking are dense enough to consume 250-300 ton lift capacity without hitting volume constraints
My guess it that any such heavy payload will be some sort of expensive one-off. If you can afford to pay for it, you can also afford to pay SpaceX for a custom SS to launch it. That custom SS would be stretched, or have a hammerhead, or both, or the exotic custom payload would replace the payload section of the SS.

Offline Stan-1967

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Aside from propellent and water, what payloads are people thinking are dense enough to consume 250-300 ton lift capacity without hitting volume constraints
My guess it that any such heavy payload will be some sort of expensive one-off. If you can afford to pay for it, you can also afford to pay SpaceX for a custom SS to launch it. That custom SS would be stretched, or have a hammerhead, or both, or the exotic custom payload would replace the payload section of the SS.

Both points above are very good.  Some space based telescopes may bump up against the volume constraints of SS, but will be just fine for mass.  The very few payloads that bump up against the +200ton lift capacity will very likely be very expensive bespoke payloads.

I do very much like the idea of SpaceX bidding version of SS itself as an orbiting space station.  I do think a space station is intended to stay in space, not consistently be going back & forth from the surface, so all the instruments one may want to jam into a Starship based space station would maybe bump into the mass limit if you had to launch it all in one launch.  The other case i think of for +200ton is to build a space station where basically the payload capacity is maximized to launch the largest possible habitable volume.  I've recently been going through old threads on XL fairings ( hammerhead, or conventional) and see that much research has been done on this.

https://forum.nasaspaceflight.com/index.php?topic=25103.0
and here...
https://forum.nasaspaceflight.com/index.php?topic=42664.0

I went to these old threads while contemplating what would be possible for SpaceX to bid as a space station concept.  if you intend to keep it in orbit, it may make sense to launch the largest possible habitable volume, as well as a volume with plenty of room for equipment delivered on subsequent flights.  The general consensus of literature on the subject it that a fairing should not exceed 1.7X the core diameter.  Exception would be for some of the hammerhead designs done for the ATLAS V. 

Attached below here is a quick render of a SS-XL mounted to a SH core.  The SS remains a 9 meter core for the first 10 meters so it can mate cleanly to SH & existing launch mount equipment, but then transition to a 15 meter diameter with a 10 meter stretch on the length. 

When I calculated the mass this structure would add if made of 4mm steel, it came out to around 90tons.  That still leaves plenty of margin to put lots of equipment inside, as well as more margin for strengthening the structure.  That would push it to the max payload mass quite easily. 



Offline Stan-1967

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And pretty please nobody call this a "Corndog rocket"   8)

Online oldAtlas_Eguy

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Aside from propellent and water, what payloads are people thinking are dense enough to consume 250-300 ton lift capacity without hitting volume constraints
My guess it that any such heavy payload will be some sort of expensive one-off. If you can afford to pay for it, you can also afford to pay SpaceX for a custom SS to launch it. That custom SS would be stretched, or have a hammerhead, or both, or the exotic custom payload would replace the payload section of the SS.

Both points above are very good.  Some space based telescopes may bump up against the volume constraints of SS, but will be just fine for mass.  The very few payloads that bump up against the +200ton lift capacity will very likely be very expensive bespoke payloads.

I do very much like the idea of SpaceX bidding version of SS itself as an orbiting space station.  I do think a space station is intended to stay in space, not consistently be going back & forth from the surface, so all the instruments one may want to jam into a Starship based space station would maybe bump into the mass limit if you had to launch it all in one launch.  The other case i think of for +200ton is to build a space station where basically the payload capacity is maximized to launch the largest possible habitable volume.  I've recently been going through old threads on XL fairings ( hammerhead, or conventional) and see that much research has been done on this.

https://forum.nasaspaceflight.com/index.php?topic=25103.0
and here...
https://forum.nasaspaceflight.com/index.php?topic=42664.0

I went to these old threads while contemplating what would be possible for SpaceX to bid as a space station concept.  if you intend to keep it in orbit, it may make sense to launch the largest possible habitable volume, as well as a volume with plenty of room for equipment delivered on subsequent flights.  The general consensus of literature on the subject it that a fairing should not exceed 1.7X the core diameter.  Exception would be for some of the hammerhead designs done for the ATLAS V. 

Attached below here is a quick render of a SS-XL mounted to a SH core.  The SS remains a 9 meter core for the first 10 meters so it can mate cleanly to SH & existing launch mount equipment, but then transition to a 15 meter diameter with a 10 meter stretch on the length. 

When I calculated the mass this structure would add if made of 4mm steel, it came out to around 90tons.  That still leaves plenty of margin to put lots of equipment inside, as well as more margin for strengthening the structure.  That would push it to the max payload mass quite easily.
Ummmmm....... Just the payload section of a 1.7X expanded diameter is a ~3,700m^3 volume.

At 100m^3 (5mx4mx5m) per person which very large per person volume for the current ISS rate of 55m^3 is room for 36 persons.

Offline wannamoonbase

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Seems to me there are two 'expendable' scenarios.

1) Fully expend SH and SS
2) Reuse SH, expend SS

When I first read this I only considered SS being expended.

I agree with the question on what payloads may need all the mass of an expendable SS.  I think it maybe a volume limit and not mass.  A SS with an expendable fairing could so some interesting missions.

I'd like to know the mass to LEO of an expended SS with a reused SH but with a fairing.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5 (Welp a little early on IFT-4, but still have a shot at 5)

Tags: rocket SpaceX 
 

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