Author Topic: Starship Methox RCS Thrusters  (Read 85673 times)

Offline CorvusCorax

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Re: Starship Methox RCS Thrusters
« Reply #220 on: 06/24/2021 09:18 am »
https://twitter.com/elonmusk/status/1407969457411067905

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

"for now" -- according to the tweet ;)

Offline kevinof

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Re: Starship Methox RCS Thrusters
« Reply #221 on: 06/24/2021 09:33 am »
or the simpler way of looking at it is "they are in development but we're not going to let that development hold back the first flight".

https://twitter.com/elonmusk/status/1407969457411067905

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

Offline Cheapchips

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Re: Starship Methox RCS Thrusters
« Reply #222 on: 06/24/2021 09:45 am »

They presumably have at least two more SN20 style tests in the works, given how they've run their testing to date.  They'd still have those opportunities to flight test the Methox RCS ahead of a catch attempt.

Offline _MECO

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Re: Starship Methox RCS Thrusters
« Reply #223 on: 06/24/2021 11:14 am »

They presumably have at least two more SN20 style tests in the works, given how they've run their testing to date.  They'd still have those opportunities to flight test the Methox RCS ahead of a catch attempt.
Which is where you need them. Although I do wonder about the speed it takes for Super Heavy to swing around and do a boostback burn on methox vs nitrogen. I get that for the first orbital test the booster's going to be ending up in the drink but every second before reigniting those engines is hundreds more meters downrange.

Offline steveleach

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Re: Starship Methox RCS Thrusters
« Reply #224 on: 06/24/2021 12:37 pm »

They presumably have at least two more SN20 style tests in the works, given how they've run their testing to date.  They'd still have those opportunities to flight test the Methox RCS ahead of a catch attempt.
Which is where you need them. Although I do wonder about the speed it takes for Super Heavy to swing around and do a boostback burn on methox vs nitrogen. I get that for the first orbital test the booster's going to be ending up in the drink but every second before reigniting those engines is hundreds more meters downrange.
I suspect Elon is ruthlessly constraining the scope of orbital launch #1 to minimise schedule delays, and any non-trivial attempts to improve landing accuracy have been rejected.

I bet there are dozens of conversations a day along the lines of...

Engineer: "we could test the microconflagulator on the orbital flight by just adding..."
Elon: "No"


Offline _MECO

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Re: Starship Methox RCS Thrusters
« Reply #225 on: 06/24/2021 01:54 pm »

They presumably have at least two more SN20 style tests in the works, given how they've run their testing to date.  They'd still have those opportunities to flight test the Methox RCS ahead of a catch attempt.
Which is where you need them. Although I do wonder about the speed it takes for Super Heavy to swing around and do a boostback burn on methox vs nitrogen. I get that for the first orbital test the booster's going to be ending up in the drink but every second before reigniting those engines is hundreds more meters downrange.
I suspect Elon is ruthlessly constraining the scope of orbital launch #1 to minimise schedule delays, and any non-trivial attempts to improve landing accuracy have been rejected.

I bet there are dozens of conversations a day along the lines of...

Engineer: "we could test the microconflagulator on the orbital flight by just adding..."
Elon: "No"
Of course. The best part is no part. The best launch vehicle is a steel bulkhead atop a shaft with a nuclear weapon at the bottom 8)
« Last Edit: 06/24/2021 01:54 pm by _MECO »

Offline steveleach

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Re: Starship Methox RCS Thrusters
« Reply #226 on: 06/24/2021 02:01 pm »

They presumably have at least two more SN20 style tests in the works, given how they've run their testing to date.  They'd still have those opportunities to flight test the Methox RCS ahead of a catch attempt.
Which is where you need them. Although I do wonder about the speed it takes for Super Heavy to swing around and do a boostback burn on methox vs nitrogen. I get that for the first orbital test the booster's going to be ending up in the drink but every second before reigniting those engines is hundreds more meters downrange.
I suspect Elon is ruthlessly constraining the scope of orbital launch #1 to minimise schedule delays, and any non-trivial attempts to improve landing accuracy have been rejected.

I bet there are dozens of conversations a day along the lines of...

Engineer: "we could test the microconflagulator on the orbital flight by just adding..."
Elon: "No"
Of course. The best part is no part. The best launch vehicle is a steel bulkhead atop a shaft with a nuclear weapon at the bottom 8)
Sorry, I didn't mean to imply that there would never be RCS on it. Just that Elon could well be saying "not for launch #1" a lot.

Re: Starship Methox RCS Thrusters
« Reply #227 on: 06/24/2021 02:45 pm »

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

A change in operational design vs a change in one prototype to reduce the amount of variables. Completely different, unrelated things.

Offline edzieba

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Re: Starship Methox RCS Thrusters
« Reply #228 on: 06/24/2021 03:48 pm »

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

A change in operational design vs a change in one prototype to reduce the amount of variables. Completely different, unrelated things.
Adding and removing a paper engine vs. adding and removing a now actual physical engine (not the case until the last few months).

Offline envy887

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Re: Starship Methox RCS Thrusters
« Reply #229 on: 06/24/2021 03:49 pm »

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

A change in operational design vs a change in one prototype to reduce the amount of variables. Completely different, unrelated things.
Adding and removing a paper engine vs. adding and removing a now actual physical engine (not the case until the last few months).

Perhaps it's a fit check with a non-flight unit. They stacked and unstacked an entire booster a couple months ago.

Offline Hauerg

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Re: Starship Methox RCS Thrusters
« Reply #230 on: 06/24/2021 03:53 pm »

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy
They habe the time and the tools to do a test installation on flight hardware.
Somwhat.
Nothing to see here.

A change in operational design vs a change in one prototype to reduce the amount of variables. Completely different, unrelated things.
Adding and removing a paper engine vs. adding and removing a now actual physical engine (not the case until the last few months).

Offline edzieba

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Re: Starship Methox RCS Thrusters
« Reply #231 on: 06/24/2021 03:54 pm »

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

A change in operational design vs a change in one prototype to reduce the amount of variables. Completely different, unrelated things.
Adding and removing a paper engine vs. adding and removing a now actual physical engine (not the case until the last few months).

Perhaps it's a fit check with a non-flight unit. They stacked and unstacked an entire booster a couple months ago.
"Any insufficiently flight-ready hardware is indistinguishable from a mass-simulator".

Offline envy887

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Re: Starship Methox RCS Thrusters
« Reply #232 on: 06/24/2021 05:41 pm »

So the hot-gas thrusters have been:
- Added for Starship flip
- Removed for Starship flip (Raptors only)
- Re-added for Starship in-orbit ops (and possibly Lunar Starship)
- Added to Super Heavy
- Removed from Super Heavy

A change in operational design vs a change in one prototype to reduce the amount of variables. Completely different, unrelated things.
Adding and removing a paper engine vs. adding and removing a now actual physical engine (not the case until the last few months).

Perhaps it's a fit check with a non-flight unit. They stacked and unstacked an entire booster a couple months ago.
"Any insufficiently flight-ready hardware is indistinguishable from a mass-simulator".

Nothing wrong with a mass simulator for parts they don't need yet. Flying ASAP is more important then landing on the first try.

Offline oldAtlas_Eguy

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Re: Starship Methox RCS Thrusters
« Reply #233 on: 06/24/2021 07:35 pm »
They may have the thrusters. But what they may not have is the GCH4 and GO2 systems and storage worked out yet. So just use the Methox thrusters in cold gas mode with GN2 tanks.Would give enough control for the stage separation and attitude control prior to Raptor burns as well as for prop settling.

Offline sevenperforce

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Re: Starship Methox RCS Thrusters
« Reply #234 on: 06/24/2021 08:02 pm »
On the igniter, it looks like they haven't hooked up the gox line yet, so that will be something to watch out for. The line that is attached looks like it taps off the fuel inlet and has no valve between it and the igniter, so they might be doing a fuel lead and lag with the fuel always running through the igniter as a purge.
Do they need a GOX line in the igniter?

The ignition sequence could be:

1. Press CH4 through igniter
2. Send GOX through chamber at low press
3. Spark to ignite
4. GOX and CH4 into chamber at full press

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