totm nov 2023 SpaceX Discussion Thread

[Xd the great]

1 hour ago, CatastrophicFailure said:

So... Silver Surfer Skydiver recovery for the booster as well? Makes sense, I suppose... if it’s stainless it can probably easily take the entry heating from only Mach a few, and with aerodynamic deceleration, that saves the entry burn entirely and only need a landing burn from a much lower terminal velocity, hmm...

That would certainly be a sight to see. 

Mostly cuz we’d actually get to see it. 

Thats why they havent tapered back the fairing, but use the bulkhead for protecting stuff.

But how will the fins and canards react to a blunt head?

"Tintin rockets look fun, lets make more!"

 

[magnemoe]

2 hours ago, Xd the great said:

Thats why they havent tapered back the fairing, but use the bulkhead for protecting stuff.

But how will the fins and canards react to a blunt head?

"Tintin rockets look fun, lets make more!"

 

Blunt head will give more drag on top. 
And benefit of this is less fuel used for braking burn you just need return to launch site and landing burn. 

[Xd the great]

40 minutes ago, magnemoe said:

Blunt head will give more drag on top. 
And benefit of this is less fuel used for braking burn you just need return to launch site and landing burn. 

Can they do droneship recovery for superheavy?

[magnemoe]

1 hour ago, Xd the great said:

Can they do droneship recovery for superheavy?

Possible, don't think its so much wider than falcon 9 with legs. its far heavier however, probably need an ship like blue origin plan to use. No plans for it as I know and moving it onshore would require an harbor, its an shipbroker 15 km away upland by an channel who has an sort of harbor.

[sevenperforce]

17 hours ago, Xd the great said:

And how will starship stock up the TEATAB engine ignitor fluid on Mars?

TEA-TEB was used for the dev Raptor, but the production raptor will use vapor ignition, probably with a couple of redundant spark ignitors.

Vaporization of RP-1 to LEL is nearly impossible (that's why it's safer than petrol), but methane vaporizes easily and ignites readily. For example, any gas stove.

So the engine can restart as many times as it wants, no ignition fluid required. Top off props and go.

Edited February 1, 2019 by sevenperforce

[sevenperforce]

14 hours ago, Mad Rocket Scientist said:

Is it dual bell or not?

It is definitely not dual bell; it would be twice as large if it was.

Looks more like an altitude-compensating concavity nozzle a la SSME. Compare to https://airandspace.si.edu/sites/default/files/styles/slideshow_xlg/public/images/collection-objects/record-images/A20040205000CP06.jpg

(Explanation: the bell expands wider than a SL engine close to the throat, leading to over-expansion at SL, but then tapers back at the edge so that the pressure at the rim is equal to atmospheric. Leads to low pressure (vacuum-optimized) at the center of the exhaust flow and high pressure (SL-optimized) at the edge of the exhaust flow. Not as much altitude-compensation as an aerospike, but not nearly as heavy or complex, either.)

 

 

 

[tater]

All the changes are really to get this bird flying ASAP. I can't express how cool this is to watch.

The change to landing the booster in a way that actually makes sense (legs), radically decreases risk---risk of losing a vehicle, expensive ground equipment (launchpad), schedule, and cost.

 

[DDE]

11 minutes ago, tater said:

The change to landing the booster in a way that actually makes sense (legs), radically decreases risk---risk of losing a vehicle, expensive ground equipment (launchpad), schedule, and cost.

 

What Arthur Clarke called “catching an egg” only really makes sense woth something like a nuclear lightbulb - if you land amywhere but the pad with its rad-shielded engine pit, it’s a loss of craft either way.

[tater]

4 minutes ago, DDE said:

What Arthur Clarke called “catching an egg” only really makes sense woth something like a nuclear lightbulb - if you land amywhere but the pad with its rad-shielded engine pit, it’s a loss of craft either way.

They were pushing rapid turn around (P2P, for example) where this makes some sense, I suppose. For actual spaceflight, they have no need to have the turn around so fast, for rendezvous, you need the next flyover, and since their launch site is not equatorial, this means one window a day or so. Longer if they do a highly elliptical orbit.

Honestly, a better solution would be to make a giant Roomba that also functions as the hold down.

Land on pad. Roomba attaches, then drives booster to blast trench, where it clamps on to hold downs on the trench.

[RedKraken]

The change to steel got BFR moving fast.

And looks like a much stronger, simpler and cheaper design.

Transpiration cooling for reentry looks promising...but represents most of the project risk.

We have a junkyard hopper built in about 10 weeks. Flying soon.

And a BFS prototype being built in parallel, due this year.

We have new raptors on the test stands.

Now we have booster design simplified from cradle to BFS style landing legs.

And cold gas thrusters ??? wait! what?

Elon is really pushing hard.

This is the best show on the planet right now.

[Ultimate Steve]

16 minutes ago, RedKraken said:

This is the best show on the planet right now.

Hopefully it will leave the planet soon!

 

[magnemoe]

16 minutes ago, RedKraken said:

The change to steel got BFR moving fast.

And looks like a much stronger, simpler and cheaper design.

Transpiration cooling for reentry looks promising...but represents most of the project risk.

We have a junkyard hopper built in about 10 weeks. Flying soon.

And a BFS prototype being built in parallel, due this year.

We have new raptors on the test stands.

Now we have booster design simplified from cradle to BFS style landing legs.

And cold gas thrusters ??? wait! what?

Elon is really pushing hard.

This is the best show on the planet right now.

Two effects here, first might be investor related.
Second is starlink, he need starship to launch this fully. Note that this is probably that the investors are most interested in. 

And yes its exiting. 

[sh1pman]

18 hours ago, Mad Rocket Scientist said:

Big. Very big.

[RedKraken]

from alhenry1231 at NSF,

chonk, thic, smol.

https://forum.nasaspaceflight.com/index.php?PHPSESSID=3mnvqm2u62b0p33hn43ev5oqo0&topic=41363.1540

Some folks think that raptors size has suddenly changed.

I don't think so.

You still have to fit 31 of these under 9m tanks....even with a 10m skirt.

[KSK]

Now *that* is a seriously badS looking piece of hardware!

And forget 'Heart of Gold' (cool name though it is) - Starship Raptor is where it's at for naming that first launch vehicle.

 

[Ozymandias_the_Goat]

 

2 hours ago, RedKraken said:

This is the best show on the planet right now.

Gives kpop a run for its money I guess.

Spoiler

I’m kidding

 

10 hours ago, Xd the great said:

Can they do droneship recovery for superheavy?

Certainly there are no plans for it in the works (yet) but I don’t see why it could not be done.

[sh1pman]

20 minutes ago, Ozymandias_the_Goat said:

I don’t see why it could not be done.

I do. It costs more than RTLS landing. With fully reusable system difference in maximum payload doesn’t really matter that much; cost increase from droneship operations, on the other hand, may be undesirable. 

[sevenperforce]

Starship+Superheavy is so massively overpowered for any typical payload that they will never need the extra margin of downrange recovery.

[tater]

2 hours ago, RedKraken said:

Some folks think that raptors size has suddenly changed. 

I don't think so.

You still have to fit 31 of these under 9m tanks....even with a 10m skirt.

We don't know how big the guy in the picture is, but if he's the same height as the scale human in drawings, that nozzle is larger than 1.3m.  Heck, if he's taller than 4' 6" that's bigger than 1.3m.

[Nightside]

28 minutes ago, tater said:

We don't know how big the guy in the picture is, but if he's the same height as the scale human in drawings, that nozzle is larger than 1.3m.  Heck, if he's taller than 4' 6" that's bigger than 1.3m.

The picture claims he is 6’ but you can see he is standing on his tip toes.

 

 

edit: you probably meant that photo from earlier.

Edited February 1, 2019 by Nightside

[tater]

[Nightside]

2 minutes ago, tater said:

Yeah that’s the one. Hard to say how close the guy is to the Raptor, he is probably not right underneath it.

[Spaceception]

5 hours ago, RedKraken said:

The change to steel got BFR moving fast.

And looks like a much stronger, simpler and cheaper design.

Transpiration cooling for reentry looks promising...but represents most of the project risk.

We have a junkyard hopper built in about 10 weeks. Flying soon.

And a BFS prototype being built in parallel, due this year.

We have new raptors on the test stands.

Now we have booster design simplified from cradle to BFS style landing legs.

And cold gas thrusters ??? wait! what?

Elon is really pushing hard.

This is the best show on the planet right now.

And aren't they going to start Superheavy booster construction within the next few months? Updates, updates, updates. But now I really can't wait to see interior shots of the Starship (CG shots are okay), and that presentation that will happen when the hopper flies.

52 minutes ago, sevenperforce said:

Starship+Superheavy is so massively overpowered for any typical payload that they will never need the extra margin of downrange recovery.

Ooh, you're right. It made sense in the back of my head, but yeah. They'll never need to expend the booster, or land on a droneship.

Edited February 1, 2019 by Spaceception

[StrandedonEarth]

I never had any expectation or idea about how big Raptors would be. It's the first time I saw one and it looked huge. The powerhead looks pretty long relative to the bell too, but that's probably because the combustion chamber is surrounded by plumbing, and it's not a vacuum bell. Then again, here's the powerhead of an SSME, also wrapped around the chamber.

1 hour ago, Spaceception said:

They'll never need to expend the booster, or land on a droneship.

Although it may be easier/simpler to land in Africa or Spain. Just kidding I know that's way too far. Although Boca Chica to Florida may be more doable. Or a natural gas drilling platform in the Gulf of Mexico, to refuel...

 

[Xd the great]

2 hours ago, Spaceception said:

And aren't they going to start Superheavy booster construction within the next few months?

Wonder how that will look.