totm nov 2023 SpaceX Discussion Thread

[kerbiloid]

44 minutes ago, Jacke said:

I remember one rule-of-thumb from old rocket design texts I read a while ago: assume CO, not CO₂, in the exhaust.  The exact proportions of what reacts to what depends on the temperature and pressure and changes somewhat in the gas as it expands in the nozzle.

Probably, but they never used methane, only heavy hydrocarbons, so (CH₂)n.
So, “A customer can have a car painted any color he wants as long as it’s black”

[tater]

 

[Raven Industries]

26 minutes ago, tater said:

 

Looks almost like they've gotten it all ready for top men to work on it. 

maybe bury it in a warehouse too

Edited September 2, 2019 by Raven Industries

[ThatGuyWithALongUsername]

LabPadre, the StarHopper stream guy, is flying a plane over the site right now, and he's streaming it live... ish...

(Stream is actually down at the moment, this happened last time too. Maybe it will come back briefly.)

 

Oh, and that Google Earth landing site thing? Here, have some low-res but neat perspective shots of them. Maybe I'll go back and overlay the HiRISE images later, too. Maybe.

Spoiler

Site 1:

Site 2:

Site 3:

Site 4:

Site 5:

Site 6:

 

Edited September 2, 2019 by ThatGuyWithALongUsername

[CatastrophicFailure]

34 minutes ago, Raven Industries said:

Looks almost like they've gotten it all ready for top men to work on it. 

maybe bury it in a warehouse too

Top.... men....

Spoiler

 

[satnet]

14 hours ago, Jacke said:

I remember one rule-of-thumb from old rocket design texts I read a while ago: assume CO, not CO₂, in the exhaust.  The exact proportions of what reacts to what depends on the temperature and pressure and changes somewhat in the gas as it expands in the nozzle.

The SpaceX environmental impact study includes a third party simulation of the exhaust products (page 169).

Per the summary:

  Calculations were performed to estimate the far-field exhaust constituents of the SpaceX Raptorliquid oxygen-liquid methane (LOX-LCH4) booster rocket engine firing under sea-level conditions. Although the exit-plane exhaust is fuel-rich and contains high concentrations of carbon monoxide (CO), subsequent entrainment of ambient air results in nearly complete conversion of the CO into carbon dioxide (CO2). A small amount of thermal nitrous oxides (NOx) is formed, all as NO. The CO and NO emissions are predicted to be less than 0.024 lbm/s each, per engine under nominal power (100%) operation. No soot is predicted to be generated by this engine cycle. The CO and NO emission rates for the Super Heavy has been estimated to be no more 0.788 lbm/s each. The predicted sea-level CO and NO emission rate for the Starship upper stage are estimated to be no more than 0.168 lbm/s each.

Table 3: Thrust Chamber Nozzle Exit Species Mass Fraction from VIPER Simulation

Species	Mass Fraction
CO2	0.39950
H2O	0.41333
CO	0.12071
O2	0.054752
H2	0.007462
OH	0.0035882

 

[mikegarrison]

1 hour ago, satnet said:

The SpaceX environmental impact study includes a third party simulation of the exhaust products (page 169).

Per the summary:

  Calculations were performed to estimate the far-field exhaust constituents of the SpaceX Raptorliquid oxygen-liquid methane (LOX-LCH4) booster rocket engine firing under sea-level conditions. Although the exit-plane exhaust is fuel-rich and contains high concentrations of carbon monoxide (CO), subsequent entrainment of ambient air results in nearly complete conversion of the CO into carbon dioxide (CO2). A small amount of thermal nitrous oxides (NOx) is formed, all as NO. The CO and NO emissions are predicted to be less than 0.024 lbm/s each, per engine under nominal power (100%) operation. No soot is predicted to be generated by this engine cycle. The CO and NO emission rates for the Super Heavy has been estimated to be no more 0.788 lbm/s each. The predicted sea-level CO and NO emission rate for the Starship upper stage are estimated to be no more than 0.168 lbm/s each.

Table 3: Thrust Chamber Nozzle Exit Species Mass Fraction from VIPER Simulation

Species	Mass Fraction
CO2	0.39950
H2O	0.41333
CO	0.12071
O2	0.054752
H2	0.007462
OH	0.0035882

 

Essentially all CO emitted from any source gets oxidized into CO2. However, given the high temperature of a rocket exhaust, I bet a lot of it does happen relatively quickly.

[tater]

You can see a fin left of the tent.

Edited September 3, 2019 by tater

[CatastrophicFailure]

So this is interesting... like train wreck interesting...

Apparently SpaceX allegedly “refused” to move a StarLink sat out of the way of an ESA bird.  Now, according to the train wreck comments, the only Starlink at a similar altitude to the ESA sat is one of two that’s slowly deorbiting itself, which +the slow-responding ion thruster May have been the reason it couldn’t move. 

Whole thing needs to be taken with a great big grain of salt for now, but there it is. 

ETA: Better article, mentioning a different computer pegged the chance of a collision as pretty negligible. 

Edited September 3, 2019 by CatastrophicFailure

[CatastrophicFailure]

1 hour ago, tater said:

You can see a fin left of the tent.

I love that there are bits of rocket ships just laying around outside like that. 

Looks like they’re working on a new tent Quonset hut shelter space, too, and maybe the beginning of another ring jig?

Now, if I were the head of that there steelworks, knowing there were drones overhead all hours of the day, I’d start leaving all kindsa stuff laying around just to mess with people...

10m steel ring... surplus space shuttle wing... giant rubber chicken with a sailor hat and a vat of mayo from Costco...

 

[KSK]

16 minutes ago, CatastrophicFailure said:

Now, if I were the head of that there steelworks, knowing there were drones overhead all hours of the day, I’d start leaving all kindsa stuff laying around just to mess with people...

Crates conspicuously marked with ACME? Mound o' birdseed?

 

[mikegarrison]

46 minutes ago, CatastrophicFailure said:

I love that there are bits of rocket ships just laying around outside like that.

Not unusual. At Boeing they have airplane fuselages sitting in the parking lot (for a while). They come in by train from Kansas. They come 2-3 at a time on the train and they go into the factory one at a time, so they sit in the parking lot waiting their turn.

One time when I was in Bordeaux I saw A380 fuselage parts being barged up the river.

(Neither of these are actually pictures I took, just pictures of things I've seen.)

Edited September 3, 2019 by mikegarrison

[mikegarrison]

It's very different from satellites that are built in a clean room and kept super-sealed until launch. These products are going to have to sit out in the weather IRL, so they can handle a little rain. Starship is probably built with similar techniques.

Edited September 3, 2019 by mikegarrison

[CatastrophicFailure]

33 minutes ago, KSK said:

Crates conspicuously marked with ACME? Mound o' birdseed?

 

“Don’t dead, open inside” 

14 minutes ago, mikegarrison said:

Not unusual. At Boeing they have airplane fuselages sitting in the parking lot (for a while). They come in by train from Kansas. They come 2-3 at a time on the train and they go into the factory one at a time, so they sit in the parking lot waiting their turn.

Not unusual for airplanes, rockets tho... I’d be surprised to see SLS bits just sitting out like that, or even Atlas.

Musk does want to make the whole mess more airplane-like, tho, hmm...m

[mikegarrison]

1 minute ago, CatastrophicFailure said:

Not unusual for airplanes, rockets tho... I’d be surprised to see SLS bits just sitting out like that, or even Atlas.

Musk does want to make the whole mess more airplane-like, tho, hmm...m

Yeah, well if your rocket is only going to be launched the one time, it doesn't have to be as rough and robust as if it's going to be launched 10 times (or whatever they are aiming for).

[RealKerbal3x]

That’s either half of a fin, or significant changes have been made to the landing leg/flaperon design.

[Val]

Removed a few posts regarding a missing image, which became clutter once the image was restored.

[Technical Ben]

2 hours ago, CatastrophicFailure said:

So this is interesting... like train wreck interesting...

Apparently SpaceX allegedly “refused” to move a StarLink sat out of the way of an ESA bird.  Now, according to the train wreck comments, the only Starlink at a similar altitude to the ESA sat is one of two that’s slowly deorbiting itself, which +the slow-responding ion thruster May have been the reason it couldn’t move. 

Whole thing needs to be taken with a great big grain of salt for now, but there it is. 

ETA: Better article, mentioning a different computer pegged the chance of a collision as pretty negligible. 

Do they lack the ability? Or legal recourse. I agree it's poor for SpaceX to not move it. But also that I don't know the capabilities of each satellite, or who is at fault (SpaceX for not checking, or ESA for forgetting to tell SpaceX a bird was already there?).

[Xd the great]

1 hour ago, Technical Ben said:

Do they lack the ability? Or legal recourse. I agree it's poor for SpaceX to not move it. But also that I don't know the capabilities of each satellite, or who is at fault (SpaceX for not checking, or ESA for forgetting to tell SpaceX a bird was already there?).

Maybe ESA forgot, maybe SpaceX couldn't move because "we need to test the deorbit system", maybe.

[Wjolcz]

3 hours ago, RealKerbal3x said:

That’s either half of a fin, or significant changes have been made to the landing leg/flaperon design.

Looks to me like the hinge part we've seen before.

[Technical Ben]

1 hour ago, Xd the great said:

Maybe ESA forgot, maybe SpaceX couldn't move because "we need to test the deorbit system", maybe.

Seems others are reporting it's one of the dead SpaceX sats. So, "dead".

 

I guess SpaceX still have some work to iron out with their designs. Also "chance of collision", so it's for safety, and not necessarily and emergency.

[mikegarrison]

As I understand it, with sats it's always "a chance of collision" not a certainty of collision/no-collision. Yeah, they track them very closely, but even orbital space is big and sats are small and orbits perturb.

It seems to me that is SpaceX wants to put 12000 satellites in orbit (more than the total of all the satellites that have ever been put into orbit until now), it's a bad idea to get an immediate reputation as a bad neighbor.

[Wjolcz]

55 minutes ago, mikegarrison said:

As I understand it, with sats it's always "a chance of collision" not a certainty of collision/no-collision. Yeah, they track them very closely, but even orbital space is big and sats are small and orbits perturb.

It seems to me that is SpaceX wants to put 12000 satellites in orbit (more than the total of all the satellites that have ever been put into orbit until now), it's a bad idea to get an immediate reputation as a bad neighbor.

But if it was a dead one then they couldn't do anything anyway. If it was an active but decaying one I don't think moving it would hurt them that much.

It could have been an active one though. If so, they must be really cheap to produce if they are willing to sacrifice one of them just like that.

[tater]

 

[Technical Ben]

2 minutes ago, tater said:

[cut for simplicity, see above]

 

So basically, someone accidentally allowed the ESA email to go in the "spam" folder. XD

Logistical problem. Not really as big as they made out. A phone call would have probably sorted it.