totm nov 2023 SpaceX Discussion Thread

[Nuke]

i think they inherited a lot of stuff from the military wrt connectors. these are highly standardized and domestically produced by a number of contractors to ensure constant supply. at least thats the way it was. we might be using a completely different set of connectors now. i cant imagine the old connectors having very good characteristics for high speed digital information. not sure if civilian (including spacex) craft use the same connectors or not. seems it would make sense, its just a connector and if you got the bread you can just buy one (milspec so probably expensive).

Edited June 20 by Nuke

[AckSed]

https://arstechnica.com/space/2024/06/ars-live-recap-is-spacex-a-launch-company-or-a-satellite-communications-company/

Transcript of talk here: https://cdn.arstechnica.net/wp-content/uploads/2024/06/Starlink-Conversation-Transcript.txt

tl;dr With Starlink, SpaceX is the largest satellite operator in the world right now, both in sheer numbers of sats and ground stations, and in revenue: Viasat/Inmarsat and Intelsat/SES ~$4 billion, Starlink $6.6 billion. They have a foot in the door with Indonesia, which is a prime market for satellite internet. If they enter India, despite the recalcitrance India is showing to OneWeb, that's an even bigger market.

Estimated launch costs are below $20 million.

[Deddly]

10 hours ago, tater said:

If they were to send up a Dragon, they'd probably just send one up, not add seats. As far as I know they're still aiming for the 26th to send Starliner home (?).

Or they could send one up  with empty IVA suits

[tater]

1 hour ago, Deddly said:

Or they could send one up  with empty IVA suits

Yeah, they'd have to I think (unless the hose couplings are the same for different suit types (which in retrospect, they should be in future if they aren't).

[JoeSchmuckatelli]

8 hours ago, Deddly said:

Or they could send one up  with empty IVA suits

Or just adapters? 

Are the seats too specific to SX suits that no one else could ride? 

- I know a Cosmonaut has ridden Crew Dragon... Did he have a SX suit? 

[tater]

46 minutes ago, JoeSchmuckatelli said:

Or just adapters? 

Are the seats too specific to SX suits that no one else could ride? 

- I know a Cosmonaut has ridden Crew Dragon... Did he have a SX suit? 

All crew who go up in Soyuz wear Russian suits. All who go in Dragon wear SpaceX suits, etc.

Spoiler

 

 

 

 

[DAL59]

https://cdn.discordapp.com/attachments/881015698191712317/1253547962659766303/Selection_Decision_Document_-_Rapid_Design_Studies_for_MSR_-_June_2024.pdf?ex=66764104&is=6674ef84&hm=bc3eee5177f103a813109b64c7bc26f37b02efe6511653e35672ddfec3ee77e6

 

SpaceX is now officially telling Nasa it could land on Mars in 2029!

[Nuke]

i guess their collection system is a  guy in a suit.

[JoeSchmuckatelli]

18 minutes ago, DAL59 said:

telling Nasa it could land on Mars in 2029

Likely the only entity that could without risking a serious eye roll cramp. 

Ambitious but not absurd 

[darthgently]

https://imgur.com/rjyNyIr

 

Edited June 21 by darthgently

[Jacke]

14 hours ago, DAL59 said:

SpaceX is now officially telling Nasa it could land on Mars in 2029!

Well, well, well....

Let's see if SpaceX gets anything beyond LEO/GTO before 2029....  Well, besides a few Falcon Heavies.

Edited Saturday at 06:13 AM by Jacke

[Flavio hc16]

15 hours ago, Nuke said:

i guess their collection system is a  guy in a suit.

Tesla bot

[JoeSchmuckatelli]

7 hours ago, Jacke said:

Well, well, well....

Let's see if SpaceX gets anything beyond LEO/GTO before 2029....  Well, besides a few Falcon Heavies.

Here are the 2020 predictions for reference 

https://spacenews.com/spacexs-2020-ambitions-tempered-by-2019-outcomes/

[Brotoro]

11 hours ago, Jacke said:

Well, well, well....

Let's see if SpaceX gets anything beyond LEO/GTO before 2029....  Well, besides a few Falcon Heavies.

And the Falcon 9 launches of Euclid toward Sun-Earth L2 and Odysseus moon lander. 

[tater]

Loads of stuff in here. Including a decent segment on why you need to just fly stuff. They simulate and test all they can on the ground (look at the complex "can crushers" and thrust simulators), but test stands are not experiencing X gs, and maneuvering. Basically everything that sensible people here have been saying since forever.

[Ultimate Steve]

And confirmation on injecting several hundred kilos of ice into the tanks.

[Brotoro]

20 minutes ago, Ultimate Steve said:

And confirmation on injecting several hundred kilos of ice into the tanks.

Which is just flippin weird.

[tater]

2 minutes ago, Brotoro said:

Which is just flippin weird.

Combustion products of CH₄ and LOX are CO₂ and H₂O.

The pressurization gas is turbopump exhaust.

[Brotoro]

Using the turbopump exhaust to pressurize is the weird part. I was expecting some sort of heat exchanger. No-part-is-best-part is fine, but not if it forces you to add other parts like better LOX tank filters and ice-catching sieves, or whatever they added for IFT-4.

Edited Saturday at 07:11 PM by Brotoro

[Ultimate Steve]

5 minutes ago, Brotoro said:

Using the turbopump exhaust to pressurize is the weird part. I was expecting some sort of heat exchanger. No-part-is-best-part is fine, but not if it forces you to add other parts like better LOX tank filters and ice-catching sieves, or whatever they added for IFT-4.

I did the math for another chat somewhere else, at a minimum, assuming I did the math right, you would need 77.5 megawatts just for the phase change on super heavy (assumed super heavy was entirely lox, bc I couldn't be bothered). More for inefficiencies, more if you want the gas to be anything higher than 91 kelvin. And then you have to pump fuel and exhaust through it which is gonna lead to some efficiency losses. More connections, possibly another pump system, something that has to be built into all 33 engines...

However I don't really know what a 77.5 megawatt heat exchanger would look like. That sounds like a big number but super heavy is so big that it could be a tiny number.

I don't know enough about heat exchangers and raptor to do more than a simple ballpark "how much heat moves through this wall" with guesstimate temperatures and materials and thicknesses. So I really couldn't tell you if it's a bone headed decision or something that was heavy and complex enough that filters looked like (or are) the better option.

[Brotoro]

I don't think you would use all 33 engines to pressurize the tank… only three engines are running at various times, so I'd think you need to use those to do the pressurization.

Edited Saturday at 09:37 PM by Brotoro

[Ultimate Steve]

16 minutes ago, Brotoro said:

I don't think you would use all 33 engines to pressurize the tank… only three engines are running at various times, so I'd think you need to use those to do the pressurization.

The volume of gas that needs to enter the tank is proportional to the number of engines running. Doing everything off of those three means you run into trouble if one of those three fail, and during times when fewer than 33 engines are running you have far more pressurization than needed and need to deal with that somehow. Plus, they really want as few variants of the engine as possible. Granted the header tanks probably have a different pressurization system (in the video, one of the ship (?) header tanks was shown to use COPVs, unsure about super heavy). If I were designing this, it would probably either be its own system (maybe with its own burner) or one per engine. It is definitely possible to do it on just a few engines though. With what I know, I don't believe that would be the best way.

Also, very off topic, but I really loved Long Term on Laythe back in the day and I don't think that has ever come up in conversation.

[Brotoro]

Early on, I thought autogenous pressurization and Starship heatshield would be the two biggest problems. I was surprised at how quickly they seemed to solve the first one…but it appears they are still working on getting it right.

Thanks for the comment about my Long-term Laythe missions. 

[magnemoe]

4 hours ago, Ultimate Steve said:

I did the math for another chat somewhere else, at a minimum, assuming I did the math right, you would need 77.5 megawatts just for the phase change on super heavy (assumed super heavy was entirely lox, bc I couldn't be bothered). More for inefficiencies, more if you want the gas to be anything higher than 91 kelvin. And then you have to pump fuel and exhaust through it which is gonna lead to some efficiency losses. More connections, possibly another pump system, something that has to be built into all 33 engines...

However I don't really know what a 77.5 megawatt heat exchanger would look like. That sounds like a big number but super heavy is so big that it could be a tiny number.

I don't know enough about heat exchangers and raptor to do more than a simple ballpark "how much heat moves through this wall" with guesstimate temperatures and materials and thicknesses. So I really couldn't tell you if it's a bone headed decision or something that was heavy and complex enough that filters looked like (or are) the better option.

You already use the methane for cooling so you can just tap off the hot gas just before firing. Lox goes straight into the top turbo pump so they tap into the flow after the burner where you have hot oxygen but also co2 and steam. 
This is an issue more so as if you have an heating loop, that to do with the oxygen not needed? 
 

[Nuke]

5 hours ago, Brotoro said:

Using the turbopump exhaust to pressurize is the weird part. I was expecting some sort of heat exchanger. No-part-is-best-part is fine, but not if it forces you to add other parts like better LOX tank filters and ice-catching sieves, or whatever they added for IFT-4.

arent you hurting your isp if you hold on to exhaust products from the turbopump. i guess its useful for margarita night on the iss.

4 hours ago, Ultimate Steve said:

I did the math for another chat somewhere else, at a minimum, assuming I did the math right, you would need 77.5 megawatts just for the phase change on super heavy (assumed super heavy was entirely lox, bc I couldn't be bothered). More for inefficiencies, more if you want the gas to be anything higher than 91 kelvin. And then you have to pump fuel and exhaust through it which is gonna lead to some efficiency losses. More connections, possibly another pump system, something that has to be built into all 33 engines...

However I don't really know what a 77.5 megawatt heat exchanger would look like. That sounds like a big number but super heavy is so big that it could be a tiny number.

I don't know enough about heat exchangers and raptor to do more than a simple ballpark "how much heat moves through this wall" with guesstimate temperatures and materials and thicknesses. So I really couldn't tell you if it's a bone headed decision or something that was heavy and complex enough that filters looked like (or are) the better option.

thats like a third of a skylon precooler.