Poll

What are the odds of SN8 survining its 20km hop?

100%
18 (2.3%)
>95%
9 (1.2%)
>90%
29 (3.8%)
>80%
98 (12.8%)
>60%
113 (14.8%)
50/50
257 (33.6%)
>40%
66 (8.6%)
>30%
86 (11.2%)
>20%
51 (6.7%)
>10%
16 (2.1%)
No chance it survives!
23 (3%)

Total Members Voted: 766

Voting closed: 09/28/2020 08:55 am


Author Topic: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion  (Read 1158106 times)

Offline CardBoardBoxProcessor

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #460 on: 09/01/2020 06:07 pm »
https://twitter.com/RGVaerialphotos/status/1300817179097563140
So - they finally disassembled the two-post metal stand / jig thing that appears to have been built and never used. I always wondered what that was all about...

Looks like it was supposed be a ring or bulkhead flipper.

Online sferrin

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #461 on: 09/01/2020 08:16 pm »
Itís worth remembering that while itís really cool to have a lot of fire at the flamey end, the less thrust starship generates while doing the same job, the better!
Compare Delta IV Heavy to Titan IVB. 
"DARPA Hard"  It ain't what it use to be.

Offline inonepiece

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #462 on: 09/01/2020 08:27 pm »
If they can't launch in 20mph wind, they're going to miss a lot of launches out here.

It's an empty beer can for these hops. Quite sensitive to wind. A full beer can on a full stack launch will be more robust.
But what about when the beer can comes back empty to land?

Offline Johnnyhinbos

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #463 on: 09/01/2020 08:29 pm »
They've laid in some serious electrical service / wiring to the gas well area. A lot. Like, substation scale service.

Thoughts:

- Substation
- Large scale generator (like, larger than what's at the solar field)
- Control Center
- Charging station for all of Nomadd and Mary's livestreaming gadgets

Image credit: BocaChicaGal
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Offline docmordrid

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #464 on: 09/01/2020 08:40 pm »
https://twitter.com/13ericralph31/status/1300538031175159809

I bet it will end up on outer ring of 20 engines (outer diameter 10m) and inner ring of 8 engines without center engine, that way every engine on ring has the same symmetric piping so it is couple of times easier in production than other variants

and outer ring engines are transfering force just on edge of bulkhead which should be ideal because force ultimately should be transfered to outer wall of the booster


Sounds like thrust has dropped quite a bit from the 16 million+ mentioned just a few days ago.   ???

I get 14.73 mlbf with 250 TF outer ring engines, 16.93 mlbf with 300 TF.
DM

Offline SkyRate

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #465 on: 09/01/2020 08:57 pm »
Are we seeing SN8 having asymmetric raceways?  It would make sense if the aerodynamic surfaces needed to be very different on windward and leeward sides, but itíll make for some interesting issues with keeping the pointy end upwards during launch.  I guess the space shuttle had to solve issues like that too, so it canít be an unsolvable problem.
That's actually not much of a problem at all. Any rocket guidance system has to deal with asymmetric forces all the time; first the wind, then gravity as soon as you turn downrange.
It's called a closed-loop control system. In simple terms, he computer knows where the rocket should be pointing and (from sensor inputs) where it actually is pointing. The bigger the difference, the bigger the response (engine gimbal angle). You do this in 2 dimensions, and also for speed, by controlling the throttle(s). Unless it's really big, the computer does not need to know about asymmetry at all...
Of course, designing the trajectory (the "should" values) is a is a little more complicated, but basically requires knowing what will give the best performance, while keeping all the loads within the allowable limits. (Hence the throttle-down around Max-Q.) You run simulations to determine this.

Offline beelsebob

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #466 on: 09/01/2020 09:21 pm »
They've laid in some serious electrical service / wiring to the gas well area. A lot. Like, substation scale service.

Thoughts:

- Substation
- Large scale generator (like, larger than what's at the solar field)
- Control Center
- Charging station for all of Nomadd and Mary's livestreaming gadgets
Supercharger station for the staff?

Offline Robotbeat

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #467 on: 09/01/2020 10:26 pm »
Are we seeing SN8 having asymmetric raceways?  It would make sense if the aerodynamic surfaces needed to be very different on windward and leeward sides, but itíll make for some interesting issues with keeping the pointy end upwards during launch.  I guess the space shuttle had to solve issues like that too, so it canít be an unsolvable problem.
That's actually not much of a problem at all. Any rocket guidance system has to deal with asymmetric forces all the time; first the wind, then gravity as soon as you turn downrange.
It's called a closed-loop control system. In simple terms, he computer knows where the rocket should be pointing and (from sensor inputs) where it actually is pointing...
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline envy887

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #468 on: 09/01/2020 10:40 pm »
https://twitter.com/13ericralph31/status/1300538031175159809

I bet it will end up on outer ring of 20 engines (outer diameter 10m) and inner ring of 8 engines without center engine, that way every engine on ring has the same symmetric piping so it is couple of times easier in production than other variants

and outer ring engines are transfering force just on edge of bulkhead which should be ideal because force ultimately should be transfered to outer wall of the booster


Sounds like thrust has dropped quite a bit from the 16 million+ mentioned just a few days ago.   ???

He tweeted that the 20 outer fixed engines would be ~300t.
8 Inner ring of deep throttling gimballing engines at ~210t 
Total still =>7500t
Given those numbers, would we expect early shut-down of some of those Raptors or a rather wild ride through the last 20-30 seconds of Superheavy operation?
Mass at staging will be over 1500 t, so even at full throttle that would imply about 5 g acceleration. That's similar to F9 and less than FH.

Offline HammerTime

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #469 on: 09/02/2020 05:51 am »
Hello everyone. I would like to say thank you to Mary and NSF for the amazing coverage of Starship. I got to show my mom and pop I am working on these vehicles. I told them to look at a certain minute in a recent video. I was wearing something my mom knows is mine. She said she was very proud of me, for the first time in many years. I will also get to show my daughter who is not old enough to understand yet that her pop works on these vehicles from the early days, vehicles that will take people to the Moon and Mars. When they are, and they will, I can show that minute of that video and point myself out. It has made me so emotional I wanted to say thank you here. Mary, you are our documentary maker. Thank you.

Offline MattDT

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #470 on: 09/02/2020 07:04 am »
They've laid in some serious electrical service / wiring to the gas well area. A lot. Like, substation scale service.

Thoughts:

- Substation
- Large scale generator (like, larger than what's at the solar field)
- Control Center
- Charging station for all of Nomadd and Mary's livestreaming gadgets
Supercharger station for the staff?
Methane production facility?

Offline ThatOldJanxSpirit

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #471 on: 09/02/2020 07:38 am »
Hello everyone. I would like to say thank you to Mary and NSF for the amazing coverage of Starship. I got to show my mom and pop I am working on these vehicles. I told them to look at a certain minute in a recent video. I was wearing something my mom knows is mine. She said she was very proud of me, for the first time in many years. I will also get to show my daughter who is not old enough to understand yet that her pop works on these vehicles from the early days, vehicles that will take people to the Moon and Mars. When they are, and they will, I can show that minute of that video and point myself out. It has made me so emotional I wanted to say thank you here. Mary, you are our documentary maker. Thank you.

Welcome to the forum!

Iím sure itís hot, dirty tiring work out there, but there are more than a few of us on this forum who would drop our comfortable desk jobs to pick up a welding torch or even a brush to help you.

Thank you, you are building our dreams.

Offline RobLynn

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #472 on: 09/02/2020 08:19 am »
20 engine ring with 8 in the middle sounds like the basis for a plug cluster should they be interested in getting a performance boost at a later date.
The glass is neither half full nor half empty, it's just twice as big as it needs to be.

Offline DusanC

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #473 on: 09/02/2020 08:37 am »
They've laid in some serious electrical service / wiring to the gas well area. A lot. Like, substation scale service.

Thoughts:

- Substation
- Large scale generator (like, larger than what's at the solar field)
- Control Center
- Charging station for all of Nomadd and Mary's livestreaming gadgets
Supercharger station for the staff?
Methane production facility?
Methane storage facility.

Offline SeaRaven

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #474 on: 09/02/2020 09:12 am »
They've laid in some serious electrical service / wiring to the gas well area. A lot. Like, substation scale service.

Thoughts:

- Substation
- Large scale generator (like, larger than what's at the solar field)
- Control Center
- Charging station for all of Nomadd and Mary's livestreaming gadgets
Supercharger station for the staff?
Methane production facility?
Methane storage facility.

Pump and compressor room.  Electrical supply and monitoring services?  I've seen a new gas station being built, and there are ducts everywhere under the forecourt
All models are wrong, but some are useful, and a large bang seems to concentrate the mind to the matter at hand

Offline kkattula

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #475 on: 09/02/2020 09:27 am »
I hope somebody knows where all this stuff goes.
 It looks like there are two 5 ring high stringered sections. Maybe for unpressurized nosecones.


Super Heavy tank barrel sections?

Offline Spock1108

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #476 on: 09/02/2020 09:29 am »
I hope somebody knows where all this stuff goes.
 It looks like there are two 5 ring high stringered sections. Maybe for unpressurized nosecones.


Super Heavy tank barrel sections?

They will be part of the SN8 and SN9 nosecone!
Francesco Maio

Offline stioks

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #477 on: 09/02/2020 09:41 am »
I hope somebody knows where all this stuff goes.
 It looks like there are two 5 ring high stringered sections. Maybe for unpressurized nosecones.

And one 4-ring section in the nosecone tent next to them. It will probably become a 5-ring section very soon.

Offline BZHSpace

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #478 on: 09/02/2020 09:45 am »
SH will have the same engine configuration as the soviet N1 rocket ?
Space will be ours soon.

Online sferrin

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Re: SpaceX Starship : Texas Prototype(s) Thread 12 : Discussion
« Reply #479 on: 09/02/2020 12:18 pm »
https://twitter.com/13ericralph31/status/1300538031175159809

I bet it will end up on outer ring of 20 engines (outer diameter 10m) and inner ring of 8 engines without center engine, that way every engine on ring has the same symmetric piping so it is couple of times easier in production than other variants

and outer ring engines are transfering force just on edge of bulkhead which should be ideal because force ultimately should be transfered to outer wall of the booster


Sounds like thrust has dropped quite a bit from the 16 million+ mentioned just a few days ago.   ???

I get 14.73 mlbf with 250 TF outer ring engines, 16.93 mlbf with 300 TF.


https://twitter.com/elonmusk/status/1300700639786340353


He also seems to mix and match tons and metric tons (~10% difference) at times so it's never clear which he means. For example using 300 tons for the outer 20 and 210 tons for the inner 8 you get 15.36 mlbf.  13.36 mlbf for 250 tons engines.  Again, significantly less than the 16.5 million mentioned a few weeks ago.  Not sure how you came up with your numbers as he used "tons" not "tonnes".
« Last Edit: 09/02/2020 12:26 pm by sferrin »
"DARPA Hard"  It ain't what it use to be.

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