Poll

Should IPD be considered on the timeline of the Raptor development?

Yes, IPD milestones directly flowed into Raptor.
5 (15.6%)
Yes, But only include the milestones I'll post about.
1 (3.1%)
Yes, But only as a general disclaimer at the beginning of the timeline.
10 (31.3%)
No, IPD milestones flowed into Raptor but all technology builds on past technology.
8 (25%)
No.
8 (25%)

Total Members Voted: 32

Voting closed: 08/25/2020 07:14 pm


Author Topic: SpaceX Raptor engine - General Thread 2  (Read 1268864 times)

Offline Chris Bergin

SpaceX Raptor engine - General Thread 2
« on: 02/23/2019 04:27 pm »
Master Thread 2 (General, updates and discussion) for the Raptor Engine.

Thread 1:
https://forum.nasaspaceflight.com/index.php?topic=41363.0

Master Article:
https://www.nasaspaceflight.com/2016/10/its-propulsion-evolution-raptor-engine/ - by Alejandro G. Belluscio.

Additional Articles relating to Raptor:
https://www.nasaspaceflight.com/?s=Raptor

L2 Resources:
https://forum.nasaspaceflight.com/index.php?topic=47345.0 <---Start here. Includes additional links ranging back to the start of the McGregor test stand facility for Raptor through to subscale and current Raptor on the stand hires and continually updated overhead photos etc. Additional L2 areas for performance and vehicle content.
« Last Edit: 08/04/2019 04:33 pm by gongora »
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Offline Jcc

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Re: SpaceX Raptor engine - General Thread 2
« Reply #1 on: 02/24/2019 12:18 pm »
I'm mostly curious to see whether the Raptor will see continued improvements over the year like the Merlin did.

Let's imagine the case where they managed to uprate the chamber pressure by some absolutely crazy factor to say, 35-40 MPa. What would the most likely change to the design be? A tank stretch like on the Falcon to increase payload, or maybe reducing the number of engines to match the increased thrust, and using the extra space to increase the expansion ratio to squeeze out more Isp?

All of these may be possible, plus improvements in reliability. But the "next big thing" after getting a stable flight proven Raptor is a Vacuum Raptor. Which leads to a redesign of the Starship thrust structure, etc.

Offline ncb1397

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Re: SpaceX Raptor engine - General Thread 2
« Reply #2 on: 02/26/2019 08:52 am »
https://twitter.com/elonmusk/status/1094782854007910400

I find this graph just fascinating. What software was used to graph it? Why does the line stop at 10.74 when the data view stops at 10.76. The X axis is presumably seconds but why wouldn't the software label that axis. Was it cropped intentionally and to what end? Anyways, if the X axis is seconds, Raptor exceeded the operational pressure of the RD-180 by .7% for 30 milliseconds which makes this not as big of a deal as it seems at first glance. Was this the test that damaged a Raptor and that explains the data stopping at 10.74?
« Last Edit: 02/26/2019 08:53 am by ncb1397 »

Offline HVM

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Re: SpaceX Raptor engine - General Thread 2
« Reply #3 on: 02/26/2019 09:51 am »
The answer for that:

Reagan Beck:
‏@bluemoondance74
"Have the most recent tests in McGregor been Merlins or Raptors? The last 4+ have seemed very similar... w/ one exception last wk (Fri. night)"

Elon Musk:
‏Verified account @elonmusk
"Merlins. The max chamber pressure run damaged Raptor SN 1 (as expected). A lot of the parts are fine for reuse, but next tests will be with SN 2, which is almost done."

e.g. Yes.
« Last Edit: 02/26/2019 09:54 am by HVM »

Offline jpo234

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Re: SpaceX Raptor engine - General Thread 2
« Reply #4 on: 02/26/2019 09:57 am »
It seems Tom Mueller is not longer a SpaceX employee:

https://twitter.com/lrocket/status/1099411086711746560

Quote
Not true, I am an advisor now. Elon and the Propulsion department are leading development of the SpaceX engines, particularly Raptor.  I offer my 2 cents to help from time to time
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Online Johnnyhinbos

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Re: SpaceX Raptor engine - General Thread 2
« Reply #5 on: 02/26/2019 09:59 am »
It seems Tom Mueller is not longer a SpaceX employee:

https://twitter.com/lrocket/status/1099411086711746560

Quote
Not true, I am an advisor now. Elon and the Propulsion department are leading development of the SpaceX engines, particularly Raptor.  I offer my 2 cents to help from time to time
Do we know how long this has been? When I read that tweet I kinda had a sinking sensation.
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Offline jpo234

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Re: SpaceX Raptor engine - General Thread 2
« Reply #6 on: 02/26/2019 10:03 am »
It seems Tom Mueller is not longer a SpaceX employee:

https://twitter.com/lrocket/status/1099411086711746560

Quote
Not true, I am an advisor now. Elon and the Propulsion department are leading development of the SpaceX engines, particularly Raptor.  I offer my 2 cents to help from time to time
Do we know how long this has been? When I read that tweet I kinda had a sinking sensation.

https://www.linkedin.com/in/thomas-mueller-2094513b/

You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline kevinof

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Re: SpaceX Raptor engine - General Thread 2
« Reply #7 on: 02/26/2019 10:08 am »
Looks like he's been splitting his time between propulsion and mars since 2016.  That (to me) shows the engineering team in SpaceX is growing up, gaining domain knowledge and taking the designs forward, while Tom Mueller moves to other areas that need attention.

Offline jpo234

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Re: SpaceX Raptor engine - General Thread 2
« Reply #8 on: 02/26/2019 10:13 am »
...Tom Mueller moves to other areas that need attention.

Don't kid yourself. He is retiring.
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline hkultala

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Re: SpaceX Raptor engine - General Thread 2
« Reply #9 on: 02/26/2019 10:22 am »
According to his linkedin page, Tom is still working for SpaceX.

It looks like he has just downshifted into a less stressful position, being around for anybody to ask him for help, but not leading the development anymore.

He has achieved a LOT in the last 16 years so it's very understandable that he might want to take it easier for a while, and have more time for his car racing projects etc.

The development of Raptor is getting closer to be ready and they have the engine they need for Mars colonization. The important parts of his job is ready, others can continue tweaking it even when he is not leading the project.
« Last Edit: 02/26/2019 10:28 am by hkultala »

Offline Dante2121

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Re: SpaceX Raptor engine - General Thread 2
« Reply #10 on: 02/26/2019 11:40 am »
...Tom Mueller moves to other areas that need attention.

Don't kid yourself. He is retiring.

Can you blame him? Heís 55 and has been at Spacex since the beginning.  Iíd be willing to bet he has cashed out stock.  Iím sure he needed a less stressful role after all that.

Offline kevinof

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Re: SpaceX Raptor engine - General Thread 2
« Reply #11 on: 02/26/2019 11:54 am »
Not kidding myself. he's been moving into the background for the last 2/3 years and will probably continue to "fade away" until he's fully retired. And why not. He's put in a good shift.

...Tom Mueller moves to other areas that need attention.

Don't kid yourself. He is retiring.

Offline RoboGoofers

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Re: SpaceX Raptor engine - General Thread 2
« Reply #12 on: 02/26/2019 12:29 pm »
He also said at an award ceremony that he wasn't primarily responsible for the M1D upgrades and that it was really the team he had built up. So it sounds like he's in more a advisory/leadership position instead of a hands-dirty engineering role.

And it's not a surprise since I would bet that they are surpassing the point where his past experience (or anyone's experience) is instructive.
Yeah, well, you know, that's just like, ah, your opinion, man.

Re: SpaceX Raptor engine - General Thread 2
« Reply #13 on: 02/26/2019 01:00 pm »
Tom's title change loosely corresponds with Jeff's title change.

Offline HVM

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Re: SpaceX Raptor engine - General Thread 2
« Reply #14 on: 02/26/2019 01:27 pm »
https://twitter.com/elonmusk/status/1100370443460988928

Quote
Tom did an awesome job leading Merlin, Kestrel, Draco & other engine developments from start through 2014 that were critical to SpaceXís success. Great respect & appreciation!
Ok, I read this more close what jpo234 says.
« Last Edit: 02/26/2019 01:29 pm by HVM »

Offline LouScheffer

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Re: SpaceX Raptor engine - General Thread 2
« Reply #15 on: 02/26/2019 03:26 pm »
It's interesting that Musk said in this tweet that
Quote
SpaceX Merlin architecture is simpler than staged combustion (eg SSME or RD), but it has world record for thrust/weight & thrust/cost engine. Raptor has better Isp, but Iím worried it may fall short on those two critical metrics.

This to me implies that Musk is not confident about second stage recovery.  If he was, then cost/engine is not a critical metric, since all engines are recovered and re-used.  The difference can be at least a factor of 2 - if you re-use a F9 booster 9 times, then you've thrown away 1/2 your engines (9 engines on the booster are recovered and re-used, and 9 MVacs are discarded).  If you can really achieve full re-use, and particularly with many re-uses, then the engine cost is hardly critical. 
« Last Edit: 02/26/2019 03:29 pm by LouScheffer »

Offline meberbs

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Re: SpaceX Raptor engine - General Thread 2
« Reply #16 on: 02/26/2019 03:39 pm »
This to me implies that Musk is not confident about second stage recovery.  If he was, then cost/engine is not a critical metric, since all engines are recovered and re-used.  The difference can be at least a factor of 2 - if you re-use a F9 booster 9 times, then you've thrown away 1/2 your engines (9 engines on the booster are recovered and re-used, and 9 MVacs are discarded).  If you can really achieve full re-use, and particularly with many re-uses, then the engine cost is hardly critical.
Starships that get sent to Mars will at most be reused 10 times and it will take 20 years for that to happen. The first couple cargo ones may stay on Mars as infrastructure. They want to in the nearish future send large fleets. Engine cost will not be negligible.

That is without getting into early development costs, and the fact that they should be expected to lose a couple stages (first and/or second) during testing.
« Last Edit: 02/26/2019 03:40 pm by meberbs »

Offline RoboGoofers

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Re: SpaceX Raptor engine - General Thread 2
« Reply #17 on: 02/26/2019 03:41 pm »
This to me implies that Musk is not confident about second stage recovery.  If he was, then cost/engine is not a critical metric, since all engines are recovered and re-used.  The difference can be at least a factor of 2 - if you re-use a F9 booster 9 times, then you've thrown away 1/2 your engines (9 engines on the booster are recovered and re-used, and 9 MVacs are discarded).  If you can really achieve full re-use, and particularly with many re-uses, then the engine cost is hardly critical.
I read his tweet as Raptor won't break Merlin's records. of course, it doesn't need to.

This would be a better quote re: Second stage recovery
https://twitter.com/elonmusk/status/1098774309781233664
That kinda puts the last nail in the coffin.
« Last Edit: 02/26/2019 05:12 pm by RoboGoofers »
Yeah, well, you know, that's just like, ah, your opinion, man.

Offline ZachF

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Re: SpaceX Raptor engine - General Thread 2
« Reply #18 on: 02/26/2019 04:45 pm »
It's interesting that Musk said in this tweet that
Quote
SpaceX Merlin architecture is simpler than staged combustion (eg SSME or RD), but it has world record for thrust/weight & thrust/cost engine. Raptor has better Isp, but Iím worried it may fall short on those two critical metrics.

This to me implies that Musk is not confident about second stage recovery.  If he was, then cost/engine is not a critical metric, since all engines are recovered and re-used.  The difference can be at least a factor of 2 - if you re-use a F9 booster 9 times, then you've thrown away 1/2 your engines (9 engines on the booster are recovered and re-used, and 9 MVacs are discarded).  If you can really achieve full re-use, and particularly with many re-uses, then the engine cost is hardly critical.

I think you're reading too much into it. More likely he set big goals (like he usually does with everything) for Raptor and the goal of beating Merlin in TWR and T$R may not happen.
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Offline uhuznaa

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Re: SpaceX Raptor engine - General Thread 2
« Reply #19 on: 02/26/2019 07:28 pm »
It's interesting that Musk said in this tweet that
Quote
SpaceX Merlin architecture is simpler than staged combustion (eg SSME or RD), but it has world record for thrust/weight & thrust/cost engine. Raptor has better Isp, but Iím worried it may fall short on those two critical metrics.

This to me implies that Musk is not confident about second stage recovery.  If he was, then cost/engine is not a critical metric, since all engines are recovered and re-used.  The difference can be at least a factor of 2 - if you re-use a F9 booster 9 times, then you've thrown away 1/2 your engines (9 engines on the booster are recovered and re-used, and 9 MVacs are discarded).  If you can really achieve full re-use, and particularly with many re-uses, then the engine cost is hardly critical.

While they may wreck a few prototypes along the way Starship makes only sense if it turns out to be reusable. Cost/engine is always a critical metric if you need so many of them. There will be 42 + 7 on every first + second stage, that's a lot of money, and more if you want to build many ships to go to Mars of which several will stay.

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