SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion

[wannamoonbase]

Forgive me if this is being discussed elsewhere.

I watched this video today, our very own Chris Bergin was representing.



Nice update and makes me mor optimistic about when we may see the next flight.

Great job Chris.

[Alberto-Girardi]

What do you think about which ship will go with B9 for the OFT 2? (feels crazy to be talking about the second, but it is real).

From Rbotbeat transcript of the Elon Musk interview

Hey, Elon, just a quick question, Chris from NSF.
Are you looking to fly with Booster 9 and Ship 28 for this next flight? Are you still deciding that one? Because there are 25s at Macy's, isn't there? I'm done if you're going with 25 or 28.
We've not made a final decision on the ship.
That's why I was referring to Booster 9, but I did not mention the ship number.
Oh, no.
So good catch there.
Yeah, I think we'll probably make that decision this week.
But we do want to bet on success in the sense that if we get to orbit, it would be super helpful to try to de-orbit and see how well the ship heat shield works.
Because we need to maintain control in hypersonic high heating regime, then get through transonic, and then maintain control all the way through a very wide array of Mach regimes.
So the vehicle actually behaves differently with radically different heating and force at the various -- coming back from roughly Mach 23 to zero.
So, yes, I think we want to have that option.
So I think we'll put a ship on that gives us that capability.
But we haven't decided exactly what ship number it should be.

bold is mine

My take is that they will go with S28. Already the fact that they are deciding is evidence against S26, thoght to be the candidate. I think given how Elon sounded optimistic that they will reach orbit they will go with a ship with a heat shield.
Another important factor is the huge aerodynamic difference given S26 doesn't have flaps. In the OFT thread we talked about how that greatly influences the center of pressure, hence vehicle stability and need for TVC from booster engines, so potentially flying S28 might be a bigger TVC load and so test the new electric system to a normal load, and not a maybe reduced one like S26.

[Alberto-Girardi]

What do you think about which ship will go with B9 for the OFT 2? (feels crazy to be talking about the second, but it is real).

From Rbotbeat transcript of the Elon Musk interview

Hey, Elon, just a quick question, Chris from NSF.
Are you looking to fly with Booster 9 and Ship 28 for this next flight? Are you still deciding that one? Because there are 25s at Macy's, isn't there? I'm done if you're going with 25 or 28.
We've not made a final decision on the ship.
That's why I was referring to Booster 9, but I did not mention the ship number.
Oh, no.
So good catch there.
Yeah, I think we'll probably make that decision this week.
But we do want to bet on success in the sense that if we get to orbit, it would be super helpful to try to de-orbit and see how well the ship heat shield works.
Because we need to maintain control in hypersonic high heating regime, then get through transonic, and then maintain control all the way through a very wide array of Mach regimes.
So the vehicle actually behaves differently with radically different heating and force at the various -- coming back from roughly Mach 23 to zero.
So, yes, I think we want to have that option.
So I think we'll put a ship on that gives us that capability.
But we haven't decided exactly what ship number it should be.

bold is mine

My take is that they will go with S28. Already the fact that they are deciding is evidence against S26, thoght to be the candidate. I think given how Elon sounded optimistic that they will reach orbit they will go with a ship with a heat shield.
Another important factor is the huge aerodynamic difference given S26 doesn't have flaps. In the OFT thread we talked about how that greatly influences the center of pressure, hence vehicle stability and need for TVC from booster engines, so potentially flying S28 might be a bigger TVC load and so test the new electric system to a normal load, and not a maybe reduced one like S26.

Well, as we say in Italy, time is a gentlman and facts now more clearly point to S25 being the chosen one for B9. As far as I understand there are no major differences  between it and S28, except the heat shield being better on S28.

[Corey Mandler]

What do you think about which ship will go with B9 for the OFT 2? (feels crazy to be talking about the second, but it is real).

From Rbotbeat transcript of the Elon Musk interview

Hey, Elon, just a quick question, Chris from NSF.
Are you looking to fly with Booster 9 and Ship 28 for this next flight? Are you still deciding that one? Because there are 25s at Macy's, isn't there? I'm done if you're going with 25 or 28.
We've not made a final decision on the ship.
That's why I was referring to Booster 9, but I did not mention the ship number.
Oh, no.
So good catch there.
Yeah, I think we'll probably make that decision this week.
But we do want to bet on success in the sense that if we get to orbit, it would be super helpful to try to de-orbit and see how well the ship heat shield works.
Because we need to maintain control in hypersonic high heating regime, then get through transonic, and then maintain control all the way through a very wide array of Mach regimes.
So the vehicle actually behaves differently with radically different heating and force at the various -- coming back from roughly Mach 23 to zero.
So, yes, I think we want to have that option.
So I think we'll put a ship on that gives us that capability.
But we haven't decided exactly what ship number it should be.

bold is mine

My take is that they will go with S28. Already the fact that they are deciding is evidence against S26, thoght to be the candidate. I think given how Elon sounded optimistic that they will reach orbit they will go with a ship with a heat shield.
Another important factor is the huge aerodynamic difference given S26 doesn't have flaps. In the OFT thread we talked about how that greatly influences the center of pressure, hence vehicle stability and need for TVC from booster engines, so potentially flying S28 might be a bigger TVC load and so test the new electric system to a normal load, and not a maybe reduced one like S26.

Well, as we say in Italy, time is a gentlman and facts now more clearly point to S25 being the chosen one for B9. As far as I understand there are no major differences  between it and S28, except the heat shield being better on S28.

a major difference is actually the payload bay

[Alberto-Girardi]

What do you think about which ship will go with B9 for the OFT 2? (feels crazy to be talking about the second, but it is real).

From Rbotbeat transcript of the Elon Musk interview

Hey, Elon, just a quick question, Chris from NSF.
Are you looking to fly with Booster 9 and Ship 28 for this next flight? Are you still deciding that one? Because there are 25s at Macy's, isn't there? I'm done if you're going with 25 or 28.
We've not made a final decision on the ship.
That's why I was referring to Booster 9, but I did not mention the ship number.
Oh, no.
So good catch there.
Yeah, I think we'll probably make that decision this week.
But we do want to bet on success in the sense that if we get to orbit, it would be super helpful to try to de-orbit and see how well the ship heat shield works.
Because we need to maintain control in hypersonic high heating regime, then get through transonic, and then maintain control all the way through a very wide array of Mach regimes.
So the vehicle actually behaves differently with radically different heating and force at the various -- coming back from roughly Mach 23 to zero.
So, yes, I think we want to have that option.
So I think we'll put a ship on that gives us that capability.
But we haven't decided exactly what ship number it should be.

bold is mine

My take is that they will go with S28. Already the fact that they are deciding is evidence against S26, thoght to be the candidate. I think given how Elon sounded optimistic that they will reach orbit they will go with a ship with a heat shield.
Another important factor is the huge aerodynamic difference given S26 doesn't have flaps. In the OFT thread we talked about how that greatly influences the center of pressure, hence vehicle stability and need for TVC from booster engines, so potentially flying S28 might be a bigger TVC load and so test the new electric system to a normal load, and not a maybe reduced one like S26.

Well, as we say in Italy, time is a gentlman and facts now more clearly point to S25 being the chosen one for B9. As far as I understand there are no major differences  between it and S28, except the heat shield being better on S28.

a major difference is actually the payload bay

Do you mean the bigger "pez dispenser" and the functioning payload door?
In that case that is an important difference, but not as major as other changes involving the propulsion system (like we saw with SN15, SN20 and S24).
Also the OFT 2 will not go to a stable orbit, so I think the payload system is less important.

Maybe, big maybe, spacex is betting big on OFT2 being successful, so to do the third launch quickly after, using S28 so the can start to deploy starlinks. Not  using S28 in the second flight might be beneficial if they can already test it and certify it for flight before OFT2, in the downtime required for the orbital pad upgrade, along (or after if it is quick) S25 testing. A major problem of this argument is that they can quickly build new ships, with S29 being already being built.

[Corey Mandler]

What do you think about which ship will go with B9 for the OFT 2? (feels crazy to be talking about the second, but it is real).

From Rbotbeat transcript of the Elon Musk interview

Hey, Elon, just a quick question, Chris from NSF.
Are you looking to fly with Booster 9 and Ship 28 for this next flight? Are you still deciding that one? Because there are 25s at Macy's, isn't there? I'm done if you're going with 25 or 28.
We've not made a final decision on the ship.
That's why I was referring to Booster 9, but I did not mention the ship number.
Oh, no.
So good catch there.
Yeah, I think we'll probably make that decision this week.
But we do want to bet on success in the sense that if we get to orbit, it would be super helpful to try to de-orbit and see how well the ship heat shield works.
Because we need to maintain control in hypersonic high heating regime, then get through transonic, and then maintain control all the way through a very wide array of Mach regimes.
So the vehicle actually behaves differently with radically different heating and force at the various -- coming back from roughly Mach 23 to zero.
So, yes, I think we want to have that option.
So I think we'll put a ship on that gives us that capability.
But we haven't decided exactly what ship number it should be.

bold is mine

My take is that they will go with S28. Already the fact that they are deciding is evidence against S26, thoght to be the candidate. I think given how Elon sounded optimistic that they will reach orbit they will go with a ship with a heat shield.
Another important factor is the huge aerodynamic difference given S26 doesn't have flaps. In the OFT thread we talked about how that greatly influences the center of pressure, hence vehicle stability and need for TVC from booster engines, so potentially flying S28 might be a bigger TVC load and so test the new electric system to a normal load, and not a maybe reduced one like S26.

Well, as we say in Italy, time is a gentlman and facts now more clearly point to S25 being the chosen one for B9. As far as I understand there are no major differences  between it and S28, except the heat shield being better on S28.

a major difference is actually the payload bay

Do you mean the bigger "pez dispenser" and the functioning payload door?
In that case that is an important difference, but not as major as other changes involving the propulsion system (like we saw with SN15, SN20 and S24).
Also the OFT 2 will not go to a stable orbit, so I think the payload system is less important.

Maybe, big maybe, spacex is betting big on OFT2 being successful, so to do the third launch quickly after, using S28 so the can start to deploy starlinks. Not  using S28 in the second flight might be beneficial if they can already test it and certify it for flight before OFT2, in the downtime required for the orbital pad upgrade, along (or after if it is quick) S25 testing. A major problem of this argument is that they can quickly build new ships, with S29 being already being built.

why waste a functional door? use the other ones for data(bad wording)

[Corey Mandler]

s26 could still be useful for data, you could slap some heatshields on it and test re-entry.
would also be a lighter ship so the booster gets more performance, for a chopstick landing attempt.
or it could be used for in-orbit tests.

[Alberto-Girardi]

s26 could still be useful for data, you could slap some heatshields on it and test re-entry.
would also be a lighter ship so the booster gets more performance, for a chopstick landing attempt.
or it could be used for in-orbit tests.

I don't agree. I belive some of the thing tou say are actually impossible, like retrofitting S26 for reentry. It does not have any flap mounting hardware.
Also the second flight will have a profile equal to the first, so the booster will splash down. Elon also stated in the first starship twitter space that booster catch with chopstick is not something they will do in the first flights. Also I belive the reduced mass of S26 is not significant in permitting booster RTLS, becuase already the ship is flying with no payload.

[Corey Mandler]

s26 could still be useful for data, you could slap some heatshields on it and test re-entry.
would also be a lighter ship so the booster gets more performance, for a chopstick landing attempt.
or it could be used for in-orbit tests.

I don't agree. I belive some of the thing tou say are actually impossible, like retrofitting S26 for reentry. It does not have any flap mounting hardware.
Also the second flight will have a profile equal to the first, so the booster will splash down. Elon also stated in the first starship twitter space that booster catch with chopstick is not something they will do in the first flights. Also I belive the reduced mass of S26 is not significant in permitting booster RTLS, becuase already the ship is flying with no payload.

tiles would be for data, ships don't necessarily have to fly in order, it was just a thought

[OTV Booster]

s26 could still be useful for data, you could slap some heatshields on it and test re-entry.
would also be a lighter ship so the booster gets more performance, for a chopstick landing attempt.
or it could be used for in-orbit tests.

I don't agree. I belive some of the thing tou say are actually impossible, like retrofitting S26 for reentry. It does not have any flap mounting hardware.
Also the second flight will have a profile equal to the first, so the booster will splash down. Elon also stated in the first starship twitter space that booster catch with chopstick is not something they will do in the first flights. Also I belive the reduced mass of S26 is not significant in permitting booster RTLS, becuase already the ship is flying with no payload.

tiles would be for data, ships don't necessarily have to fly in order, it was just a thought

SN 25 can achieve all the testing goals of SN24 but with (hopefully) more reliable TVC and better engine isolation, which appears to be where the problems were. Well, that and engine reliability.


SN28 might be able to take it further but if they can't get past staging it adds nothing. By the time they do the next launch later builds could be approaching the point where SN25 lessons could be baked in. If too far advanced even later builds will get the upgrades. In the meantime SN 28 could be bypassed or used, depending on it SX thinks it can teach them something.


Worst case, SN25 & booster might only test an upgraded destruct system keeping NASA, FAA and everybody else, including SX and NSF, happy.

[Corey Mandler]

Preparing for Booster 9:

oooooooooooooooo finally it will be soooooooo weirds also bingo merch

*coughs* i mean it will be odd when b9 is on the olm, what do you think the static fire campain will be, i think it will be each ring.

[Starmang10]

s26 could still be useful for data, you could slap some heatshields on it and test re-entry.
would also be a lighter ship so the booster gets more performance, for a chopstick landing attempt.
or it could be used for in-orbit tests.

I don't agree. I belive some of the thing tou say are actually impossible, like retrofitting S26 for reentry. It does not have any flap mounting hardware.
Also the second flight will have a profile equal to the first, so the booster will splash down. Elon also stated in the first starship twitter space that booster catch with chopstick is not something they will do in the first flights. Also I belive the reduced mass of S26 is not significant in permitting booster RTLS, becuase already the ship is flying with no payload.

tiles would be for data, ships don't necessarily have to fly in order, it was just a thought

SN 25 can achieve all the testing goals of SN24 but with (hopefully) more reliable TVC and better engine isolation, which appears to be where the problems were. Well, that and engine reliability.


SN28 might be able to take it further but if they can't get past staging it adds nothing. By the time they do the next launch later builds could be approaching the point where SN25 lessons could be baked in. If too far advanced even later builds will get the upgrades. In the meantime SN 28 could be bypassed or used, depending on it SX thinks it can teach them something.


Worst case, SN25 & booster might only test an upgraded destruct system keeping NASA, FAA and everybody else, including SX and NSF, happy.

There are a bit of innacuracies there. There was no need for S25 or S28 to have engine (plumbing wise, yes) isolation. It is, however, required for the boosters since they are in mass amounts and are producing an insane amount of thrust. However, yes, you do have good points.

If SX does not get past stage seperation, they are learning nothing about the ship, if you don't count the engine ignition on S24 after the FTS-Assisted seperation, that is, and plus the strength of the ship. The entire purpose of retrofitting a ship with a full TPS system is to get data of said system, not just slap it onto the ship for good looks. Later on, touching up on what you said about ships becoming outdated, Elon said that he wishes for the ships to be easily retrofitted so they can support new adjustments in the future. Because of this, we won't have to keep seeing an S-20 situation every couple of days because of an adjustment with the ship's systems.

[OTV Booster]

s26 could still be useful for data, you could slap some heatshields on it and test re-entry.
would also be a lighter ship so the booster gets more performance, for a chopstick landing attempt.
or it could be used for in-orbit tests.

I don't agree. I belive some of the thing tou say are actually impossible, like retrofitting S26 for reentry. It does not have any flap mounting hardware.
Also the second flight will have a profile equal to the first, so the booster will splash down. Elon also stated in the first starship twitter space that booster catch with chopstick is not something they will do in the first flights. Also I belive the reduced mass of S26 is not significant in permitting booster RTLS, becuase already the ship is flying with no payload.

tiles would be for data, ships don't necessarily have to fly in order, it was just a thought

SN 25 can achieve all the testing goals of SN24 but with (hopefully) more reliable TVC and better engine isolation, which appears to be where the problems were. Well, that and engine reliability.


SN28 might be able to take it further but if they can't get past staging it adds nothing. By the time they do the next launch later builds could be approaching the point where SN25 lessons could be baked in. If too far advanced even later builds will get the upgrades. In the meantime SN 28 could be bypassed or used, depending on it SX thinks it can teach them something.


Worst case, SN25 & booster might only test an upgraded destruct system keeping NASA, FAA and everybody else, including SX and NSF, happy.

There are a bit of innacuracies there. There was no need for S25 or S28 to have engine (plumbing wise, yes) isolation. It is, however, required for the boosters since they are in mass amounts and are producing an insane amount of thrust. However, yes, you do have good points.

If SX does not get past stage seperation, they are learning nothing about the ship, if you don't count the engine ignition on S24 after the FTS-Assisted seperation, that is, and plus the strength of the ship. The entire purpose of retrofitting a ship with a full TPS system is to get data of said system, not just slap it onto the ship for good looks. Later on, touching up on what you said about ships becoming outdated, Elon said that he wishes for the ships to be easily retrofitted so they can support new adjustments in the future. Because of this, we won't have to keep seeing an S-20 situation every couple of days because of an adjustment with the ship's systems.

Yeah, on the isolation issue I got my tang tungled up in my head.


ISTM SS will need to get within spitting distance of successful EDL before the design will be stable enough to be a 'reference' design. That might be as soon as 2-3 launches or as far away as 10.


An interesting and high impact variable is, given the robustness of the stack, will structural mass be traded for increased propellant, payload or any of the thousand and one improvements that each take 'only' a little mass? My guess is they may claw back a little structural mass early on but will wait until they're near to a reference build before they'll get aggressive about it. Even then, they may decide that some robustness isn't a bad thing.

[darkenfast]

https://forum.nasaspaceflight.com/index.php?topic=54984.msg2491436#msg2491436

Well, the Space Cadet in me wanted them to be for some really big multi-pane windows, but they seem to extend for more than 180 degrees around the ring.

How about this (1): A half-section on Booster, just below the grid fins and their equipment. Open ports, so that if Starship has to abort off the Booster, these vents will function like those on the old Titan missile, which used hot-staging.

How about this (2): Bottom end of Booster, just where the tank dome slopes in. This allows for airflow into the engine bays and MAYBE cuts down on fire risk.

Note that both ideas would require lots of reinforcing around the openings.

Edit: Apologies for messing up formatting. It's the pic of a ring with what appear to be partial cut-outs (like on a model).

[simon82]

https://forum.nasaspaceflight.com/index.php?topic=54984.msg2491436#msg2491436

Well, the Space Cadet in me wanted them to be for some really big multi-pane windows, but they seem to extend for more than 180 degrees around the ring.

How about this (1): A half-section on Booster, just below the grid fins and their equipment. Open ports, so that if Starship has to abort off the Booster, these vents will function like those on the old Titan missile, which used hot-staging.

How about this (2): Bottom end of Booster, just where the tank dome slopes in. This allows for airflow into the engine bays and MAYBE cuts down on fire risk.

Note that both ideas would require lots of reinforcing around the openings.

Edit: Apologies for messing up formatting. It's the pic of a ring with what appear to be partial cut-outs (like on a model).

My guess is windows for HLS prototype, or maybe even the one for Polaris docking mission.

[CMac]

my guess: Load bearing for the pez dispenser frame? Top and bottom so load path is through the dispenser frame rather then the door area

[Crispy]

I went and looked at the stream and it's clear that there are least four repetitions of the arc pattern. Without knowing the distance from camera to subject it's impossible to know for sure, but some rough pixel counting says that the cutout pattern has sixfold symmetry. Fifteen slots and one solid "gap" repeated 6 times = 96 modules at ~300mm spacing.

The Booster and Ship engine bays have 96 stringers (booster: https://twitter.com/elonmusk/status/1420819718701780995) (ship: https://www.instagram.com/p/Cj8QP1RjeiJ/)

The one good clear shot of the payload bay that I could find (https://twitter.com/NASASpaceflight/status/1418652841376354305/photo/1) has a module of ~400mm or 72 stringers.

So if it *is* for the payload bay, they've increased the stringer count by 25% since July 2021, to match the engine bays.

Have we seen inside the payload bays of the newer Ships?

[billh]

https://forum.nasaspaceflight.com/index.php?topic=54984.msg2491436#msg2491436

Well, the Space Cadet in me wanted them to be for some really big multi-pane windows, but they seem to extend for more than 180 degrees around the ring.

How about this (1): A half-section on Booster, just below the grid fins and their equipment. Open ports, so that if Starship has to abort off the Booster, these vents will function like those on the old Titan missile, which used hot-staging.

How about this (2): Bottom end of Booster, just where the tank dome slopes in. This allows for airflow into the engine bays and MAYBE cuts down on fire risk.

Note that both ideas would require lots of reinforcing around the openings.

Edit: Apologies for messing up formatting. It's the pic of a ring with what appear to be partial cut-outs (like on a model).

I'll take door number 1. If almost all the stiffness and loadbearing comes from the stringers, this may not materially weaken the ship, but it could avoid catastrophic damage to Starship in an abort scenario. The panels might even be left in place to avoid any aerodynamic or contamination issues in normal operation. The overpressure from the engines could blow them out, if an abort ever occurred. (They would need to test that, for sure!)

[Tangilinear Interjar]

In the middle of two of the cutout patterns is a rectangular cutout that looks very similar to the cutout at the top of a booster for the support/lifting pin.

[chariotoffire]

https://forum.nasaspaceflight.com/index.php?topic=54984.msg2491436#msg2491436

Well, the Space Cadet in me wanted them to be for some really big multi-pane windows, but they seem to extend for more than 180 degrees around the ring.

How about this (1): A half-section on Booster, just below the grid fins and their equipment. Open ports, so that if Starship has to abort off the Booster, these vents will function like those on the old Titan missile, which used hot-staging.

How about this (2): Bottom end of Booster, just where the tank dome slopes in. This allows for airflow into the engine bays and MAYBE cuts down on fire risk.

Note that both ideas would require lots of reinforcing around the openings.

Edit: Apologies for messing up formatting. It's the pic of a ring with what appear to be partial cut-outs (like on a model).

Regarding (1), we're a long way away from crewed SS launching on SH, so it seems too early to be concerned with aborts. I would also expect aborts to be rare enough that it makes more sense to discard the booster than change the design to try and salvage it. If the abort is caused by the booster it is probably done for anyway.

A related possibility suggested by Warp99 is that it is the skirt section of HLS and SpaceX is trying to avoid extra landing thrusters. The vents would allow gas and regolith to escape from the engine bay while near the surface. The bases of the arches would correspond to landing leg locations that need more strength.

Edit: One problem with this theory is we've seen SpaceX reinforce the skirt, so it seems odd to take material away. Maybe they are planning to launch HLS with a light fuel load, or maybe the added reinforcement would still allow venting.