totm nov 2023 SpaceX Discussion Thread

[IncongruousGoat]

1 hour ago, RCgothic said:

I just find it odd that they're struggling with MK1 and SN1 which were both plainly better construction than Starhopper.

There's a couple of things to consider here. First, it took a lot longer for Starhopper to come together than MK1 or SN1. Some of the difficulty could be in speeding up the pace of construction without damaging quality. Second, Starhopper made a single, tiny hop before being retired from flight. That's not a very good flight rate, and I suspect SpaceX are looking to get far more mileage out of their prototypes going forward. Testing to destruction and rapid prototyping are all well and good, but if the destruction in question is due to easily-identified manufacturing defects caused by rushed construction, then it stops being useful data and starts being a waste of hardware.

Edited February 26, 2020 by IncongruousGoat

[CatastrophicFailure]

2 hours ago, IncongruousGoat said:

There's a couple of things to consider here. First, it took a lot longer for Starhopper to come together than MK1 or SN1. Some of the difficulty could be in speeding up the pace of construction without damaging quality. Second, Starhopper made a single, tiny hop before being retired from flight. That's not a very good flight rate, and I suspect SpaceX are looking to get far more mileage out of their prototypes going forward. Testing to destruction and rapid prototyping are all well and good, but if the destruction in question is due to easily-identified manufacturing defects caused by rushed construction, then it stops being useful data and starts being a waste of hardware.

This. There's a tweet upthread from Musk saying SN2 will finally lack the "post-Thanksgiving bloat" look between each of the segments, that sounds like a significant improvement in manufacturing to me, probably learned from building all the others, and I suppose there comes a time in a given iteration where the improvements learned for the next iteration make it no longer worthwhile to put much more effort into the current one. SpaceX is well known, after all, for rejecting that sunk-cost fallacy.

[ThatGuyWithALongUsername]

5 hours ago, Xd the great said:

Highly likely, turbopump cavity and RUDs occur when the tank pressure is too low.

Isn't that what people speculated almost happened at the end, though?

[magnemoe]

5 hours ago, IncongruousGoat said:

There's a couple of things to consider here. First, it took a lot longer for Starhopper to come together than MK1 or SN1. Some of the difficulty could be in speeding up the pace of construction without damaging quality. Second, Starhopper made a single, tiny hop before being retired from flight. That's not a very good flight rate, and I suspect SpaceX are looking to get far more mileage out of their prototypes going forward. Testing to destruction and rapid prototyping are all well and good, but if the destruction in question is due to easily-identified manufacturing defects caused by rushed construction, then it stops being useful data and starts being a waste of hardware.

Their problem is that they need to get the weight down a lot, they talk about 2 mm skin for production version. I can not understand how that will be able to support itself. then empty without internal bracing. Yes the raceways helps a bit 
SN1 has 4 mm, as I understand the hopper had 12 mm who is ship hull thickness and for stanles is qualified as armor. 
So they have two tasks, one is to make an workable prototype, the second is to nail the process of building an production one. 
And no the flight characteristic of an overweight starship will not match one of an proper one, they would need larger header tanks for one, and I guess they don't worry to much about touchdown even if hopper landed pretty rough. 

[Xd the great]

4 hours ago, ThatGuyWithALongUsername said:

Isn't that what people speculated almost happened at the end, though?

I mean RUD at/near the engines, not flying COPVs.

[ThatGuyWithALongUsername]

33 minutes ago, Xd the great said:

I mean RUD at/near the engines, not flying COPVs.

I wasn't talking about the COPV's. I heard talk about the exhaust suddenly changing color at the end of the flight and the crush cores on the legs being completely used up possibly meanjing the engine suffered a slight loss of thrust at the end. Not as dramatic as the RUD scenarios you mentioned but maybe itmeant something.

 

Although with skin 3 times thicker than SN1, I don't honestly think they would have had a problem with filling the tanks to flight pressure, so I don't really think there would have been a reason not to fully pressurize them. I'm pretty sure they were at full pressure anyway.

[tater]

https://www.faa.gov/space/environmental/nepa_docs/media/SpaceX_Falcon_Program_Draft_EA_508.pdf

More pics pulled from PDF:

 

[ThatGuyWithALongUsername]

2 hours ago, tater said:

https://www.faa.gov/space/environmental/nepa_docs/media/SpaceX_Falcon_Program_Draft_EA_508.pdf

More pics pulled from PDF:

DANG. They really are making sure LC-39A is the coolest looking launchpad ever, aren't they?

 

Meanwhile in a less polished launch site:

This shows that they are still working on the nosecone for SN1, even though it looks more and more likely that SN1 will not fly. I would say it's just for SN2, but isn't the whole point of SN2 is that it has better weld quality than SN1? If this was for SN1, isn't it not good enough?

Edited February 27, 2020 by ThatGuyWithALongUsername

[tater]

Falcon 9 Stage 2 propellant loads:

RP-1: 29,461 kg

LOX: 76,204 kg

(from the FH data in that PDF)

[sevenperforce]

27 minutes ago, tater said:

Falcon 9 Stage 2 propellant loads:

RP-1: 29,461 kg

LOX: 76,204 kg

(from the FH data in that PDF)

So 105.7 tonnes total S2 propellant. Interesting. I have typically been using SLR's estimate of 111.5 tonnes S2 prop loading in most analyses/simulations. Slight change for high-energy orbits, I think.

What page are you seeing that data on?

Table 2-1 on p10 says 1,135,925 lbm of total F9B5 propellant, or 515.25 tonnes, though it says there is less propellant usage for some missions. This corresponds to 409.55 tonnes S1 propellant. 

[tater]

7 minutes ago, sevenperforce said:

What page are you seeing that data on?

10

The page with the renders of F9/FH with the stretched fairing.

Edited February 27, 2020 by tater

[Flavio hc16]

look at page 16 , i would love to see this launch cadence

http://

[ThatGuyWithALongUsername]

28 minutes ago, Flavio hc16 said:

look at page 16 , i would love to see this launch cadence

http://

10 FH launches a year out of completely nowhere seems a bit odd lol

 

But for this year, at least, the startistics clearly seem to indicate actual contracted missions. Are we gonna see 3 FH launches this year?

And actually why is the F9 launch frequency so... low (for 2020)? Is Starlink just not on here or something?

[StrandedonEarth]

2 minutes ago, ThatGuyWithALongUsername said:

And actually why is the F9 launch frequency so... low (for 2020)? Is Starlink just not on here or something?

Well, it does show 30 F9 launches from LC-40. Although the preceding description doesn't specifically list Starlink, it could be lumped under "commercial," even if the customer is SpaceX itself.

[ThatGuyWithALongUsername]

18 minutes ago, StrandedonEarth said:

Well, it does show 30 F9 launches from LC-40. Although the preceding description doesn't specifically list Starlink, it could be lumped under "commercial," even if the customer is SpaceX itself.

I meant for 2020

[StrandedonEarth]

1 minute ago, ThatGuyWithALongUsername said:

I meant for 2020

?

2020 shows 30 F9 launches from LC-40

It's easy to mix up the lines on tables like that, without colors to help read straight across...

[Wjolcz]

So FH looks more and more like a conventional launch vehicle, and by 'conventional' I mean 'pricey'. I do realize that reusability reduces cost significantly and they wouldn't be investing in all that integration infrastructure if it didn't bring SpaceX revenue. I just hope Starship is operational soon-ish.

2 hours ago, ThatGuyWithALongUsername said:

This show that they are still working on the nosecone for SN1, even though it looks more and more likely that SN1 will not fly. I would say it's just for SN2, but isn't the whole point of SN2 is that it has better weld quality than SN1? If this was for SN1, isn't it not good enough?

I still don't get why everyone thinks it will not fly ('wording' is kind of a bad reason to think so, especially since that info was pulled from Elon's tweets!). The fact that only the tank was transported for now most likely means that lighter things are just easier to transport. They might still finish it if the static fire goes well.

[ThatGuyWithALongUsername]

18 minutes ago, StrandedonEarth said:

?

2020 shows 30 F9 launches from LC-40

It's easy to mix up the lines on tables like that, without colors to help read straight across...

Og, you're right, I'm just blind I guess lol

 

Well, that's one mystery solved. Now what are those 3 FH missions? (That one air force mission is one of them, ViaSat may be another?)

9 minutes ago, Wjolcz said:

So FH looks more and more like a conventional launch vehicle, and by 'conventional' I mean 'pricey'. I do realize that reusability reduces cost significantly and they wouldn't be investing in all that integration infrastructure if it didn't bring SpaceX revenue. I just hope Starship is operational soon-ish.

I still don't get why everyone thinks it will not fly ('wording' is kind of a bad reason to think so, especially since that info was pulled from Elon's tweets!). The fact that only the tank was transported for now most likely means that lighter things are just easier to transport. They might still finish it if the static fire goes well.

Yeah,  that's a fairly likely possibility, but I'm still not sure TBH...

[magnemoe]

1 hour ago, Wjolcz said:

So FH looks more and more like a conventional launch vehicle, and by 'conventional' I mean 'pricey'. I do realize that reusability reduces cost significantly and they wouldn't be investing in all that integration infrastructure if it didn't bring SpaceX revenue. I just hope Starship is operational soon-ish.

I still don't get why everyone thinks it will not fly ('wording' is kind of a bad reason to think so, especially since that info was pulled from Elon's tweets!). The fact that only the tank was transported for now most likely means that lighter things are just easier to transport. They might still finish it if the static fire goes well.

it makes lots of sense to do an pressure test before you add fins and fairings if you consider pressure testing risky. You do an second after its assembled because having an kiloton of LOX and methane mixing because the common bulkhead fails will be noisy. 

Has the pricing of FH changed? It might simply be that its no longer seen as an risky design but rather reliable so they attract more expensive payloads. 

[tater]

 

 

[Wjolcz]

3 minutes ago, magnemoe said:

Has the pricing of FH changed? It might simply be that its no longer seen as an risky design but rather reliable so they attract more expensive payloads. 

It might change once all that infrastructure is in place. This stuff needs maintenance too.

Btw, can't the Starship fly with just one engine? It's based on a lot of guesstimating but:

1. Starhopper flew with just one

2. Starship won't be fully fueled for a hop test so maybe having just 1 would be enough and comparable with Starhopper?

[CatastrophicFailure]

1 hour ago, Wjolcz said:

still don't get why everyone thinks it will not fly ('wording' is kind of a bad reason to think so, especially since that info was pulled from Elon's tweets!). The fact that only the tank was transported for now most likely means that lighter things are just easier to transport. They might still finish it if the static fire goes well.

Well, there’s the fact that they just bolted all that hardware on the outside in a very Kerbal way, and that apparently it will only have a single Raptor. It’d need all three for a 20km hop, and I don’t see the utility in a sub-20km hop. SN2 sounds like a significant improvement to the point that pushing SN1 may no longer be needed. 

[tater]

The stuff on the outside would also fit in that rear flattened area that will eventually get an additional cover, too.

[Wjolcz]

1 hour ago, tater said:

The stuff on the outside would also fit in that rear flattened area that will eventually get an additional cover, too.

It looks like it's mounted pretty close to one of the raceways. I guess SN1 won't fly after all.

[tater]