totm nov 2023 SpaceX Discussion Thread

[tater]

6 minutes ago, Spaceception said:

If you strip it down, how much could it send to TLI? Obviously, they wouldn't do that when refueling allows the vehicle to be returned, but is it more or less capable than the Saturn V?

 

TLI is ~3.2 km/s.

A stripped SS could be under 80t I would think—tanks alone, dumping nose as a fairing. At 80t dry, that's ~59t to TLI.

Up the thread I figured it would in fact be possible to make an expendable upper stage replacing SS for a lot under 80t. 40t or less. That would be ~99t to TLI.

 

[RCgothic]

21 minutes ago, Spaceception said:

If you strip it down, how much could it send to TLI? Obviously, they wouldn't do that when refueling allows the vehicle to be returned, but is it more or less capable than the Saturn V?

More capable.

250t of stage (50t dry), payload and propellant in LEO translates to about 55t pure payload to TLI. If the stage is only 40t then that's 65t to TLI.

 

Edit: I'm not counting stage as payload, but for Lunar starship that could be legitimate.

Edited August 6, 2021 by RCgothic

[sevenperforce]

32 minutes ago, Spaceception said:

If you strip it down, how much could it send to TLI? Obviously, they wouldn't do that when refueling allows the vehicle to be returned, but is it more or less capable than the Saturn V?

Stripped down and expendable, it would be vastly more capable to TLI than Saturn V.

[tater]

18 minutes ago, RCgothic said:

250t of stage (50t dry), payload and propellant in LEO translates to about 55t pure payload to TLI. If the stage is only 40t then that's 65t to TLI.

I was not counting the stage as payload either, I get larger numbers.

Payload 250t.

Add dry mass.

I_sp is 378.

TLI is 3.2km/s.

I get 75t to TLI for a 50t stripped SS.

I think you are doing payload all the way to LLO!

6 minutes ago, sevenperforce said:

Stripped down and expendable, it would be vastly more capable to TLI than Saturn V.

Which means even more capable than SLS (any block) could ever possibly be.

And they could literally make that as a variant in a few weeks.

(and they'd make a bunch of money on it charging less than a DIVH launch costs)

Edited August 6, 2021 by tater

[tater]

 

 

 

[Beccab]

1 minute ago, tater said:

 

 

Sure = two weeks

[Minmus Taster]

 

[RCgothic]

2 hours ago, tater said:

I was not counting the stage as payload either, I get larger numbers.

Payload 250t.

Add dry mass.

I_sp is 378.

TLI is 3.2km/s.

I get 75t to TLI for a 50t stripped SS.

I think you are doing payload all the way to LLO!

Which means even more capable than SLS (any block) could ever possibly be.

And they could literally make that as a variant in a few weeks.

(and they'd make a bunch of money on it charging less than a DIVH launch costs)

Ah, difference must be that I'm conservatively including stage mass in the "250t to LEO"

[tater]

3 minutes ago, RCgothic said:

Ah, difference must be that I'm conservatively including stage mass in the "250t to LEO"

I was assuming payload doesn't include vehicle.

[Dfthu]

48 minutes ago, tater said:

 

Man I hope this actually happens in the future. Making Super Heavy and Starship even bigger and more powerful. One of the most exciting things (IMO)

EDIT: Wonder if this 150 Ton reusable figure includes a possible stretch.

 

Edited August 6, 2021 by Dfthu

[mikegarrison]

These payload charts always underestimate the shuttle, because the shuttle was about more than payload. It would be as if the entire payload of the Saturn V was listed as just the weight of three astronauts and some science instruments.

[RCgothic]

Yeah, sometimes it's legitimate to count the mass of the vehicle as payload.

[mikegarrison]

10 minutes ago, RCgothic said:

Yeah, sometimes it's legitimate to count the mass of the vehicle as payload.

It all depends.

With something like a commercial airplane, payload is pretty easy to determine, because the load is literally paying to be carried.

But with something like the shuttle, it was both a delivery vehicle and also a small space station.  If you are going to count the entire capsule as "payload" for something like a Dragon, then it would make sense to count the entire shuttle orbiter as "payload". But usually people only count whatever was in the cargo bay as the payload.

[tater]

16 minutes ago, mikegarrison said:

These payload charts always underestimate the shuttle, because the shuttle was about more than payload. It would be as if the entire payload of the Saturn V was listed as just the weight of three astronauts and some science instruments.

Yeah, if the vehicle has crew I’d count the vehicle mass in there, at least for comparing systems.

”what mass is in orbit that’s supposed to be in orbit, and is not now trash” as a sort of definition?

2 minutes ago, mikegarrison said:

But with something like the shuttle, it was both a delivery vehicle and also a small space station.  If you are going to count the entire capsule as "payload" for something like a Dragon, then it would make sense to count the entire shuttle orbiter as "payload". But usually people only count whatever was in the cargo bay as the payload.

Yeah, it would be like only counting the max mass in the Dragon trunk as "payload."

[mikegarrison]

Launch mass of the orbiter was about 110,000 kg, which puts it in a much more fair perspective with SLS and Saturn V. I am not sure what they are counting as payload for that 100,000 kg for Starship.

[Meecrob]

On 8/4/2021 at 8:20 PM, Lewie said:

I just realized....

Ship 20

Booster 4

420

Nice one, Elon!

I mean, for teenagers, it might be cool, "yo 420, MOFO's!!!", but aerospace doesn't work that way. Like yes, Elon smoked on Joe Rogan, we all know, but let me stand up for the integrity of the industry and say that the only way it works is that people in it are sober. Its not like this cabal of pot smoking idiots who cobbled together a rocket...In fact, its kind of insulting, to be honest.

Edited August 6, 2021 by Meecrob

[Rakaydos]

9 minutes ago, Meecrob said:

I mean, for teenagers, it might be cool, "yo 420, MOFO's!!!", but aerospace doesn't work that way. Like yes, Elon smoked on Joe Rogan, we all know, but let me stand up for the integrity of the industry and say that the only way it works is that people in it are sober. Its not like this cabal of pot smoking idiots who cobbled together a rocket...In fact, its kind of insulting, to be honest.

It's less that it's a pothead joke, and more that it's a meme number. Elon is considered quite the "memelord" on twitter, which is one reason some people find it difficult to take him seriously.

...and if you didnt know the context, "drone ship of course I still love you" would sound quite random too. But Elon has been know to push for pop culture numerology. So ship 20/booster 4 probably isn't a complete coincidence.

[sevenperforce]

I just had a horrible, terrible, no-good thought that definitely should not be explored or discussed in any way.

What payload would Starship be able to get into low earth orbit if it had twin New Glenn side boosters?

EDIT: To be clear, I am talking about using Starship as a sustainer stage. No Superheavy booster at all. Your choice whether to cross feed from the New Glenns into Starship.

Edited August 6, 2021 by sevenperforce
Clarity

[Meecrob]

Well, no duh, He's a good marketer, but with the diverse group on this board, I wanted to make sure kids know you can't like get this job for Elon and expect to smoke weed. Legal or not, you aren't getting an aerospace job if you are a pothead. There are lots of kids on this board who probably want to get into building rockets, so we all know that the first way you do NOT get hired is because you smoke weed. Legal or not. Personally, I don't care...I'm not trying to pass my personal beliefs onto others, but I'm thinking of all the teenagers reading this that maybe the think "hey, ok, if i want this job, I should not do this" kinda thing.

As we all know, SpaceX burns people out so my advice is to go get that job, then after you quit, smoke your weed kinda thing.

Edit: either the post I was replying to was deleted, or it looks like I just smoked some weed and look stupid because there is no reference post.

Edited August 6, 2021 by Meecrob

[sevenperforce]

<snip>

Edited August 7, 2021 by sevenperforce

[RCgothic]

40 minutes ago, mikegarrison said:

Launch mass of the orbiter was about 110,000 kg, which puts it in a much more fair perspective with SLS and Saturn V. I am not sure what they are counting as payload for that 100,000 kg for Starship.

It actually makes you wonder how they managed to add an engine and two booster segments to SLS and still omehow end up with 15t fewer to LEO.

The 100t figure for starship clearly doesn't include the mass of the vehicle and landing props, which is roughly 150t right now. Actual mass to LEO for Starship would be ~250t reusable.

[tater]

55 minutes ago, mikegarrison said:

Launch mass of the orbiter was about 110,000 kg, which puts it in a much more fair perspective with SLS and Saturn V. I am not sure what they are counting as payload for that 100,000 kg for Starship.

They are counting not Starship. 
 

Cargo, or more likely, residual propellants.

If the dry mass is 100t, 100t payload means 200t got to LEO.

Actually that’s not far off Shuttle if the orbiter was 110t. Add in 25t cargo, and technically it could have taken the empty main tank as well…

 

[Lewie]

1 hour ago, Meecrob said:

I mean, for teenagers, it might be cool, "yo 420, MOFO's!!!", but aerospace doesn't work that way. Like yes, Elon smoked on Joe Rogan, we all know, but let me stand up for the integrity of the industry and say that the only way it works is that people in it are sober. Its not like this cabal of pot smoking idiots who cobbled together a rocket...In fact, its kind of insulting, to be honest.

Yes, I am a teen. No, I do not think smoking weed is a good idea. Cool? Heck no! Is it a ‘meme number?’

you betcha!

Do I think a bunch of pot heads built starship? ‘Course not. 

I’m just saying it’s a ‘funny number’ y’know...Elon IS a meme lord...

1 hour ago, Rakaydos said:

It's less that it's a pothead joke, and more that it's a meme number. Elon is considered quite the "memelord" on twitter, which is one reason some people find it difficult to take him seriously.

...and if you didnt know the context, "drone ship of course I still love you" would sound quite random too. But Elon has been know to push for pop culture numerology. So ship 20/booster 4 probably isn't a complete coincidence.

Bingo

but ya

I’m rather bummed, I was at work for the entire stacking!! You lucky ducks got to see t live! 

I think one of the things that really impresses me about SS/SH is the decoupling...how on Earth did those SpaceX engineers devise a system to hold a 1200 ton Starship on a booster?? (Seriously does anyone know anything about this?) I didn’t finish watching Tim Dodd’s interview with Elon, so....whoops. Gonna have to do that soon! 

[tater]

5 minutes ago, Lewie said:

how on Earth did those SpaceX engineers devise a system to hold a 1200 ton Starship on a booster??

If you look at the underside images of SN20 you will see 6 slots. On B4 there are 3 tabs with a rod, presumably a latch on SS grabs those. There are likely 3 tabs in the other 3 on SS such that they can be deployed for a 180 degree rotation rail to tail docking for prop transfer.

[cubinator]

4 minutes ago, Lewie said:

I think one of the things that really impresses me about SS/SH is the decoupling...how on Earth did those SpaceX engineers devise a system to hold a 1200 ton Starship on a booster?? (Seriously does anyone know anything about this?) I didn’t finish watching Tim Dodd’s interview with Elon, so....whoops. Gonna have to do that soon! 

Elon said that they are gonna tilt up the booster just before shutdown and use the angular momentum to separate the Starship and start the boostback, much like the Starlinks.

The booster will use the normal venting of the gas inside the main tanks as RCS. It's about 6 bar and would work about as well as dedicated thrusters. Dragon thrusters are about 8-9 bar.