totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

15 minutes ago, Elthy said:

I would assume they just stick some Falcon9-diameter tanks in the hopper, they allready have the tooling.

I would assume that welds strong enough to hold aero will be good enough to pump full of props.

8 hours ago, CatastrophicFailure said:

Aaaaaand now its early February.  Because politics. 

 

The view looking down that crew arm.........

[Spaceception]

So does anyone think they'll make a more robust hopper for larger tests, or will they upgrade this along the way?

 

Also, I wonder if Elon will talk about when they will build the first booster/full-scale starship.

[tater]

 

[cubinator]

[DDE]

16 hours ago, sevenperforce said:

Who knows -- maybe articulating finlegs is a bridge too far and the SpaceX aerophysics team has come up with a way to effect multiplanetary hypersonic lifting-body reusable re-entry sans moving parts. 

Seeing as shuffling fuel around in the tanks in a conteolled manner would be difficult, the only remaining option is a forcefield.

Which is less far-fetched than it might sound... but everything I’ve heard of practical applications of magnetic plasma manipulation in hypersonic aerodynamics comes from people more excited about Russian superweapons than I am.

Edited January 5, 2019 by DDE

[sevenperforce]

41 minutes ago, DDE said:

Seeing as shuffling fuel around in the tanks in a conteolled manner would be difficult, the only remaining option is a forcefield.

Maybe they realized that the weight of systems needed to actuate the moving parts would be so great that they could as easily introduce heavy pumps and bulkheads to move fuel mass around inside, changing CoM as desired.

I've actually done something like that in KSP.

[DDE]

33 minutes ago, sevenperforce said:

I've actually done something like that in KSP.

Doesn’t the Dragon use a shifting ballast, too?

[magnemoe]

1 hour ago, Elthy said:

I would assume they just stick some Falcon9-diameter tanks in the hopper, they allready have the tooling.

That would make some sense, you might even use an F9 second stage directly if the piping is good enough to feed 2-3 raptors. 

However you have this 

Not much inside, at maximum header tanks.
And its not the bottom of the fuel tank as it lack the fat pipe for oxidizer. 
Looking at the BFS drawing its also an fairly complex piping around the header tanks to, assume this is to let them switch tanks while not drawing fuel and oxidizer to all 7 engines trough the header tank. 

Now you can use internal structures to prevent fuel from sloshing around in tanks this is standard on ship and planes, but rockets drain fuel very fast making this harder. but should be doable just leave the flow direction open while restrict sideways movement except in the bottom. where fuel can flow toward the center drain. 

[StrandedonEarth]

36 minutes ago, magnemoe said:

Now you can use internal structures to prevent fuel from sloshing around in tanks this is standard on ship and planes, but rockets drain fuel very fast making this harder

Standard on rockets too. SpaceX didn't think they needed baffles on the second stage of the Falcon 1. They were wrong.

[DDE]

56 minutes ago, magnemoe said:

Now you can use internal structures to prevent fuel from sloshing around in tanks this is standard on ship and planes, but rockets drain fuel very fast making this harder. but should be doable just leave the flow direction open while restrict sideways movement except in the bottom. where fuel can flow toward the center drain. 

You need not theorize.

Even such a small rocket as the AGM-12/LR-58 Bullpup had slosh baffles in its tanks - a practice that began from Goddard himself (see fig. 5-10 in Sutton; bunch of flat disks with holes in them, hanging inside the tank).

Not to be confused with baffles on injector faces.

Edited January 5, 2019 by DDE

[tater]

 

[RedKraken]

2 hours ago, sevenperforce said:

, I have no idea where I got 204 tonnes.

Caffeine? or sleep? I have been following the hopper threads a bit too closely and i am starting to hallucinate.

Hopper/starship updates is going to be like world cup finals that go all year...

 

3 hours ago, sevenperforce said:

29% mass growth over the composite 2017

My hopper estimate was pretty crude. 

And it may not translate across to BFS/starship well at all.

Hopefully we will find out in a month or two.

i've got no idea how much propellant this contraption will carry.

 

[sevenperforce]

10 minutes ago, tater said:

 

LOL, just came over to post this.

So, did we just not see the underlying structure for the other components, or is the underskin limited to the lower sections? I could foresee near-balloon-tank upper section but reinforced lower.

Or we could be looking at something that will not translate at all to the orbital version.

1 hour ago, DDE said:

Doesn’t the Dragon use a shifting ballast, too?

Yes, but if they can use pumped props across the entire body instead of a tracked ballast sled...well, that would be epic.

40 minutes ago, RedKraken said:

My hopper estimate was pretty crude. 

And it may not translate across to BFS/starship well at all.

Hopefully we will find out in a month or two.

i've got no idea how much propellant this contraption will carry.

Upper limit is established by TWR, based on engine thrust.

[DDE]

2 hours ago, sevenperforce said:

well, that would be epic.

It won’t look like the Starship we have, probably.

[tater]

Left here entirely for the sun-headline:

https://www.theregister.co.uk/2019/01/04/spacex_crew_dragon

[tater]

I love the fact they are working at night:

 

[tater]

Wonder if this mighty missile is engorged with fuel for the static fire...

 

[StrandedonEarth]

24 minutes ago, tater said:

I love the fact they are working at night:

 

That's just gorgeous. It's so awesome that they're building it out in the open for our step-by-step entertainment, instead of hidden away in a factory with no news for months or years.

[NSEP]

Posts comparing Starship to 50s/60s Sci-Fi book covers aren't new here, but it does say that the time we live in is somewhat special.

 

[NSEP]

 

[tater]

 

[tater]

 

[sevenperforce]

12 hours ago, tater said:

Left here entirely for the sun-headline:

https://www.theregister.co.uk/2019/01/04/spacex_crew_dragon

Oh god that's too much.

1 hour ago, NSEP said:

 

So Elon's render is quite true. Mold lines around the fins are interesting...those are the areas that would take a lot of entry heating.

If the holes in the central fuselage section are thrusters, that's a good place for roll control. 

I really do wonder if we will see fixed fins on the orbital version as well.

Edited January 6, 2019 by sevenperforce

[tater]

2 minutes ago, sevenperforce said:

I really do wonder if we will see fixed fins on the orbital version as well. 

I wonder if you could do EDL with 1 fin down. In his previous talks, he said that what would be the V-stab in the skydiver entry was just for looks (and as a leg, obviously). If the v-stab was ventral instead of dorsal, and it vented fuel (or water) along the belly and fin... maybe it survives fine.

PS--this is literally the most steam punk rocket ever.

[sevenperforce]

Elon suggests that the hopper will fly with this mottled appearance but the operational starship will be nice and shiny:

https://twitter.com/elonmusk/status/1081662202124296192

^^for some reason this is not pasting in properly.

Also: https://twitter.com/elonmusk/status/1081676911066017793