Wiki Super Heavy/Starship - General Development Discussion

[JB47394]

Is the tapering really an issue in forward flight?

That's above my pay grade. I have no idea what the air flow across the body is like.

It's not like there are solid crossection, it's only the profile edge that changes.

I wouldn't be surprised to find out that the air stagnates as it reaches a squared stringer end, resulting in an aerodynamically-solid end and adding drag. Perhaps only in one regime of subsonic, transonic or supersonic, but present. That may be why they taper them on the booster.

 

[scaesare]

Here's an image of the top of a booster with its staging ring. These are the only external stringers that I'm aware of on the entire stack. Note that the ends of the stringers are tapered. The stringers on Ship 26 are not. This suggests to me that either don't have all the rows of stringers on yet or that Ship 26 isn't intended for high speed flight.

A really speculative possibility is that the stringers aren't for compressive strength, but to survive bumping into the chopsticks as they try to hover over and perform a catch. If they can't catch the thing, they'll want to land it somewhere, so if we see landing legs installed, that'll support this idea.

Hmm... I wonder if the additional stringers are for some planned flight profile changes in order to address the RUD of IFT-2?

If they decide to keep the booster thrust at a higher level to avoid Starship "kickback", there might be for stress in that area?

 

[JB47394]

If they decide to keep the booster thrust at a higher level to avoid Starship "kickback", there might be for stress in that area?

Nah. The Starship happily handles 33 engines until shortly before staging. Firing three or six engines during staging won't bother the Starship a whit.

 

[scaesare]

Nah. The Starship happily handles 33 engines until shortly before staging. Firing three or six engines during staging won't bother the Starship a whit.

Saw a couple of other theories:

- Additional strength to cut in a ring to expand the methane tank. Seems like a backwards approach and unlikely IMO.

- Reinforcement for horizontal transportation on a barge


Also, this tweet says Raptors (plural) are being removed from S28, which is thought to be the booster slated for IFT-3... however the linked video only shows one being removed... so not sure if that's just a typo...

 

[mongo]

Saw a couple of other theories:

- Additional strength to cut in a ring to expand the methane tank. Seems like a backwards approach and unlikely IMO.

- Reinforcement for horizontal transportation on a barge


Also, this tweet says Raptors (plural) are being removed from S28, which is thought to be the booster slated for IFT-3... however the linked video only shows one being removed... so not sure if that's just a typo...

That engine (yeah singular) was re-installed

 

[JB47394]

- Reinforcement for horizontal transportation on a barge

If I was doing that, I'd put a lightweight cage into the cargo area, then pressurize the tanks. The current stringers are acting against horizontal transport. Right now, they're just dead weight. They'd need hoop stiffeners to transfer the loads.

Then there's the question of where it would go and what it would do when it got there. The only useful thing I can think of is to test new GSE infrastructure from pressurization up through static fires. Does SpaceX have GSE installed at the Cape?

 

[scaesare]

If I was doing that, I'd put a lightweight cage into the cargo area, then pressurize the tanks. The current stringers are acting against horizontal transport. Right now, it's just dead weight. They'd need hoop stiffeners to transfer the loads.

Then there's the question of where it would go and what it would do when it got there. The only useful thing I can think of is to test new GSE infrastructure from pressurization up through static fires. Does SpaceX have GSE installed at the Cape?

Unsure...

 

[ecarfan]

Does SpaceX have GSE installed at the Cape?

I am not aware they have done that yet in Florida.

 

[ecarfan]

From the latest NSF Starbase update video.

After this photo was taken by SpaceX, B13 was stacked.

 

[JB47394]

I wonder how large a stable of Starships and boosters they'll have when they're finally operational, but pre-Mars colony. I wonder where they'll store them. Will they build garages? Will they use dedicated rail lines to park them and move them to various stations such as cargo loading and then to the launch tower? Or will they stick with the SPMTs? Perhaps SPMTs at Starbase, but rail lines at the Cape.

 

[ecarfan]

I wonder how large a stable of Starships and boosters they'll have when they're finally operational, but pre-Mars colony.

I suspect that in the history of non-military rocketry no commercial company has ever built this many orbital class vehicles this quickly.

I am guessing that the plan is to use this first group of vehicles to perfect as quickly as possible the landing technique over water before attempting the first Stage Zero catch. These are basically disposable prototypes.

As to how many Starships and SH boosters will be operational as a group prior to the beginning of regular launches to Mars, I would think it depends on how much commercial and government mission demand there will be outside of Starlink missions. Lunar missions will be very infrequent due to Congressional budget limitations. Commercial LEO station launches are also likely to be very limited; one or two/year? Other types of private missions (Dear Moon, Polaris) will also be infrequent. Missions like huge space telescopes will be maybe once an decade given the cost and time required to build the scope.

And how many ships/boosters SpaceX will dedicate to Starlink missions; maybe two given that a ship can handle about 100 V2 sats, right?

So that is a fairly small number of vehicles in total even including the tankers for the rare lunar missions.

 

[bxr140]

I wonder how large a stable of Starships and boosters they'll have when they're finally operational, but pre-Mars colony.

The timeline is way long to "Mars colony", as is the reality of getting to significant launch frequency (anything half as close to what F9 is today) but in general until SX starts hucking stuff beyond earth orbit I'd expect handful of operational ships and boosters at any one time. Maybe 3-5 boosters and 8-10 ships? Maybe a few more if there's significantly used variants?

Will they use dedicated rail lines to park them and move them to various stations such as cargo loading and then to the launch tower? Or will they stick with the SPMTs? Perhaps SPMTs at Starbase, but rail lines at the Cape.

IMO it's SPMT. Rail is a bit of an old school technology that's basically superseded in this use case by something newer. There's really not a lot of upside these days to the very fixed infrastructure of rail vs the dynamic use case of an SPMT that can pretty much go anywhere as long as it has a sufficiently robust surface on which to travel (and from a surface area perspective, that travelled surface generally has to be less robust than rail anyway). FWIW there's rail up and down either side of the business end of Titan road, for instance, but neither ULA nor SX--who both move rocket crap up and down the road--use the rails except for the VIF<-->LC41 transfer that AV has been using for over 20 years. (Related, mind the shoulder if you're driving on Titan road...)

Not exactly an airtight data point, but from the perspective of other new rockets, Blue has had their SPMTs sitting out in the rain at LC-36 for years now waiting for a rocket... (A6 is using rails, but that's for the building to roll back away from the pad, Delta 4 style)

 

[JB47394]

anything half as close to what F9 is today

I just wonder where all the payloads are going to come from. SpaceX could put up all the remaining Starlink satellites in a year if they were launching Starships at the 2023 pace of Falcon 9. Certainly they want to develop the operational expertise to run Starship at that pace - and far beyond, per Elon. Maybe they'll go with the Starlink extension to a total of 42,000 satellites. (!!) It would take another few years at that cadence, ignoring payloads from other customers.

IMO it's SPMT. Rail is a bit of an old school technology that's basically superseded in this use case by something newer.

Yeah, I understand the appeal of SPMTs. I was thinking more of the idea of going to a higher launch cadence than anyone has ever attempted. Just as SpaceX is trying to get to mass production of vehicles, I wonder they'll kinda work launching into the process. That is, build, launch, build, launch. SPMTs are very flexible, but that flexibility won't serve much purpose once they have the whole thing running like a colossal gatling gun. I realize that's way down the road, but surely SpaceX is thinking about stuff like that.

Or would you argue that SPMTs would be a good choice even then, given that they could probably have them drive around autonomously, as if they were on rails?

 

[bxr140]

I just wonder where all the payloads are going to come from.

That's exactly right. I haven't compiled 2023 data yet (and I don't know that I will...) but when you look at data from 2012-2022 the number of global medium+heavy launches hasn't really changed once you take out starlink (and SX only launched 6 more non-starlinks for 33 total in '23 vs 27 in '22, so not a massive jump). There's more mass year over year for sure and no question that's a direct result of Falcon, so it's not like the industry is just stagnant. But...despite the wild success of SX and Falcon, it hasn't had a 'game changing' impact on the space industry at large. It's really been more 'nice upside'.

Starship is, at least aspirationally, another step function in cost reduction so we'll almost certainly see another bump in 'nice upside'. And it really does open up the world of megaconstellations--even Falcon 9 is a bit at the limit for someone to use it to lift their megaconstellation. That said, its hard to imagine demand gets to the point where a bunch of entities want to build a bunch of megaconstellations that require many hundreds let alone thousands of tons on orbit and thus many tens of non-starlink starship launches.

Or would you argue that SPMTs would be a good choice even then, given that they could probably have them drive around autonomously, as if they were on rails?

I think so, yes. I get the point that there's maybe some well oiled, rinse-and-repeat type machine where rockets are going from the same place to the same place, but I just don't think SX will ever get to the point where they feel comfortable locking down logistical infrastructure to that level. They're constantly evolving, and I’d guess they're always going to constantly evolve to the point where more permanent infra like rails would over constrain their evolution.

And even then, even independent of volume, I don’t think SX would get to a point where they believe that level of infrastructure is actually a benefit over their existing evolution (which scales quite well).

 

[scaesare]

I suspect that in the history of non-military rocketry no commercial company has ever built this many orbital class vehicles this quickly.

<snip>

I suspect not many, if any, military organizations have either...

 

[scaesare]

From the latest NSF Starbase update video.

View attachment 1015648

After this photo was taken by SpaceX, B13 was stacked.
View attachment 1015649

No fourth row of stringers on Ship 26 yet I see...

 

[ecarfan]

At 2:05 there is a test of the booster QD retraction and hood closing. It’s quick! Seems to take less than 2 seconds.

 

[scaesare]

First the additional stringers on the S26, now new weld marks on B10:

Interesting conjecture that it may be for baffles...

 

[ecarfan]

“Super-duper slosh baffles”. This technical aeronautical language is way over my head.

 

[SwTslaGrl]

^I wonder how much extra weight these reinforcements will add? Perhaps not enough to affect the payload capacity.