totm nov 2023 SpaceX Discussion Thread

[Nefrums]

If the BFR gets cheaper than the F9 per launch there will be no need to use F9 for smaller payloads.

Imagine what that would mean for the cube sats launch costs.  

[TheDestroyer111]

26 minutes ago, Nefrums said:

If the BFR gets cheaper than the F9 per launch there will be no need to use F9 for smaller payloads.

Imagine what that would mean for the cube sats launch costs.  

Falcon 9 is also projected to be fully reusable, so if they don't get into a large amount of technical issues related to the F9's kerosene fuel that don't exist with methane, F9 will be cheaper per launch -> better for smallsats.

[tater]

3 minutes ago, TheDestroyer111 said:

Falcon 9 is also projected to be fully reusable, so if they don't get into a large amount of technical issues related to the F9's kerosene fuel that don't exist with methane, F9 will be cheaper per launch -> better for smallsats.

F9 is never projected to be fully reusable. Only booster and fairings.

[wumpus]

5 minutes ago, tater said:

F9 is never projected to be fully reusable. Only booster and fairings.

And then  only roughly 10 times (although more than 1 in 10 missions call for fully expendable launches, so this is unlikely to really be tested).

[magnemoe]

50 minutes ago, Nefrums said:

If the BFR gets cheaper than the F9 per launch there will be no need to use F9 for smaller payloads.

Imagine what that would mean for the cube sats launch costs.  

Forget cubesats, with BFR you could launch an small space station as secondary payload

 

[CatastrophicFailure]

15 minutes ago, wumpus said:

And then  only roughly 10 times (although more than 1 in 10 missions call for fully expendable launches, so this is unlikely to really be tested).

No, that’s 10 times without significant overhaul. “Many” more than 10 with refurb. Once FH is operational, there’ll be no more expendable F9 launches at all. 

I seem to recall they are going to try to recover F9 upper stages next year, but I’m guessing it’s purely for data gathering with no real intent to refly.   

[TheDestroyer111]

34 minutes ago, tater said:

F9 is never projected to be fully reusable. Only booster and fairings.

Well, at IAC 2017 Musk said something about keeping some F9's and FH's in stock for things smaller than BFR should be used for...

If only I remembered where I read it up that SpaceX is currently planning to start soft-landing the second stages next year...

27 minutes ago, wumpus said:

And then  only roughly 10 times (although more than 1 in 10 missions call for fully expendable launches, so this is unlikely to really be tested).

According to Elon Musk this will change

also

//edit lol ninjad

Edited October 28, 2017 by TheDestroyer111

[tater]

They are only ever going to experiment with S2 reuse on F9, to the extent it moves BFR forward. They said S2 reuse won't be an operational thing.

[wumpus]

40 minutes ago, CatastrophicFailure said:

No, that’s 10 times without significant overhaul. “Many” more than 10 with refurb. Once FH is operational, there’ll be no more expendable F9 launches at all. 

I seem to recall they are going to try to recover F9 upper stages next year, but I’m guessing it’s purely for data gathering with no real intent to refly.   

I strongly suspect they will fly FH while expending the center booster and get some pretty extreme delta-v that way.  That said, it is quite possible that the center booster can handle the severe aerobraking FH will require without too much of a backburn.  This is far worse than anything F9 ever saw, but critical in returning the upper stage.

Even if it is recoverable without significant backburn, losing that center stage could easily boost payload capacity by more than 25% while increasing costs by ~25% (expending the side boosters would likely be a last resort type of thing).

[CatastrophicFailure]

19 minutes ago, wumpus said:

I strongly suspect they will fly FH while expending the center booster and get some pretty extreme delta-v that way.  That said, it is quite possible that the center booster can handle the severe aerobraking FH will require without too much of a backburn.  This is far worse than anything F9 ever saw, but critical in returning the upper stage.

Even if it is recoverable without significant backburn, losing that center stage could easily boost payload capacity by more than 25% while increasing costs by ~25% (expending the side boosters would likely be a last resort type of thing).

The new Block 5 cores, which I assume the FH core is or will be based on, have a heat shield for just those kinds of high-speed reentries. SpaceX will eventually be shutting down the F9 line, the whole point for them is to stop throwing away rocket parts. Once FH is up and going, I think expendable launches of any sort will be extremely rare. 

[TheDestroyer111]

2 hours ago, CatastrophicFailure said:

expendable launches of any sort will be extremely rare

Maybe except for this

2 hours ago, wumpus said:

I strongly suspect they will fly FH while expending the center booster and get some pretty extreme delta-v that way.  That said, it is quite possible that the center booster can handle the severe aerobraking FH will require without too much of a backburn.  This is far worse than anything F9 ever saw, but critical in returning the upper stage.

Even if it is recoverable without significant backburn, losing that center stage could easily boost payload capacity by more than 25% while increasing costs by ~25% (expending the side boosters would likely be a last resort type of thing).

If FH can't launch something in fully reusable mode and it isn't some weird air force payload that needs to be launched here and now, BFR would be used rather than an even partially expendable FH - expending the core stage would not be 25% cost increase but rather something like 1000% once they reuse all stages of Falcon Heavy. They could also have the FH core land on an ASDS to maximise first stage deltaV.

Edited October 28, 2017 by TheDestroyer111

[Rune]

8 hours ago, tater said:

The dry mass of the tanker is certainly lower than the dry mass of the "spaceship" version fitted out for crew. That this fact would stay the same with the downsize from 12m to 9m is uncontroversial I would think.

Musk also said that the BFS cargo/tanker variant could take a small cargo to LEO as an SSTO. You could just as well work backwards to that, and at least rough out what the dry mass could not exceed for this to be the case.

 

Yup, but in the same place he said that, he also said initially, there would not be a dedicated tanker, and they would just use an empty BFS in order to save that development for later. So, you know, while a tanker would have to be more efficient, the whole thing must work first without it.

9 hours ago, Exoscientist said:

 

 I agree we can't be sure of the actual dry mass of the BFR tanker, but it is certainly less than the 85 tons of the BFR spaceship since it won't contain the passenger quarters and supplies for 100 colonists on a six month journey to Mars. 

  Bob Clark

Sure, it should be less. But again, we don't know how much more, and we won't know for a while for sure, because a lot of other things have to happen earlier. Musk has been sufficiently vague. And frankly, until they actually start building the thing, he really can't be anything else, because everything is (or should be) subject to change if models don't pan out. And right now they must be using rough models for a lot of stuff. Mass shouldn't scale linearly with size, for example. And the payload section in whatever drawings we have seen is nothing more than concept art.

Which is sensible, of course. To build a rocket, you first have to know what kind of legs you have to work with, and the Raptor is only now getting tested. Now that they know those key performance parameters (and it appears those 300bar were indeed a bit too much to shoot for, at least initially), they can work from there and figure out all the structures on top. At this stage is when mass growth usually happens, when you start figuring out subsystems and such.

 

Rune. So if they freeze the size, perhaps we will see a more detailed version in next year's IAC.

Edited October 28, 2017 by Rune

[tater]

The excess mass is a pressure vessel for crew, life support, other fittings. The tanker/cargo is just the empty carbon fiber shell at the top, and propellant "payload" is really the excess not needed to get to orbit because it carries no other payload.

Anyway, something like 45-50 tons would be what it is.

[DAL59]

18 hours ago, TheDestroyer111 said:

Maybe except for this

Elon Musk had a reddit AMA and when asked about that ship in the middle, said that the city isn't necessarily accurate.

[wumpus]

23 hours ago, CatastrophicFailure said:

The new Block 5 cores, which I assume the FH core is or will be based on, have a heat shield for just those kinds of high-speed reentries. SpaceX will eventually be shutting down the F9 line, the whole point for them is to stop throwing away rocket parts. Once FH is up and going, I think expendable launches of any sort will be extremely rare. 

Presumably FH should be online next year.  I'm deeply suspicious of BFR's funding.  Don't be surprised if regular Elon time gets to be "Elon time being expended as we scrounge funding".  F9 and FH have a real market, BFR's is still questionable.

However expensive a Falcon booster is, the cost of a falcon flight is much higher than that.  The only reason you won't see many expendable FH missions is the low quantity of missions which require that much mass into GTO/escape velocity.  And if you can't find a market for that, you won't find a market for BFR.

[tater]

 

[IncongruousGoat]

24 minutes ago, wumpus said:

Presumably FH should be online next year.  I'm deeply suspicious of BFR's funding.  Don't be surprised if regular Elon time gets to be "Elon time being expended as we scrounge funding".  F9 and FH have a real market, BFR's is still questionable.

However expensive a Falcon booster is, the cost of a falcon flight is much higher than that.  The only reason you won't see many expendable FH missions is the low quantity of missions which require that much mass into GTO/escape velocity.  And if you can't find a market for that, you won't find a market for BFR.

The point of BFR isn't to be a launcher for super-heavy payloads. It's to be a launcher for anything-including heavy payloads-at a fraction of the cost of an expendable, or even partially reusable launcher. The whole point is that you don't need to care about payload efficiency all that much when your only costs are fuel, range maintenance, and minor refurbishment. The real question is not whether there are payloads for BFR, because anything can be a BFR payload. It's whether SpaceX can get the marginal cost of a BFR flight low enough that the economics make sense, and that remains to be seen.

[Mitchz95]

I do wonder if and when the BFR will get a "proper" name. Maybe Falcon Super Heavy (FSH)?

[KSK]

1 hour ago, Mitchz95 said:

I do wonder if and when the BFR will get a "proper" name. Maybe Falcon Super Heavy (FSH)?

Going with Iain M. Banks theme again, I think GSV (for General Systems Vehicle) has a nice ring to it, especially given the scope of ambition for the thing.

 

[tater]

 

[CatastrophicFailure]

3 minutes ago, tater said:

 

Now that, right there, looks like a flame hole big enough for a Falcon Heavy. 

Once those white panels are removed...

[Ultimate Steve]

Aww, darn, I've got school.

Yay, the launch is during study hall!

Aww, the school blocks YouTube livestreams.

 

[tater]

 

[Nightfury]

I dunno why, but it seems they messed up the a.m. / p.m. thing for the webcast

[tater]

 

Edited October 30, 2017 by tater