Author Topic: SpaceX advances drive for Mars rocket via Raptor power  (Read 538237 times)

Offline Chris Bergin

This article is by our very own Alejandro G. Belluscio (Baldusi). Superb debut article for the site, using the info from SpaceX Co-Founder and Vice President of Propulsion Development Tom Mueller with a fascinating engine history piece.

http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/

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(EDIT: If you're reading this article in 2016, hi - now we have flying cars and robot dogs! Great! But Raptor has also evolved into this: https://www.nasaspaceflight.com/2016/10/its-propulsion-evolution-raptor-engine/ - anyway, back to 2014, and the lack of flying cars....)

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This is the first article based on comments made by Mr. Mueller at an event last month, which was attended by one of our L2 members (by chance!) We've been working the information provided at that meeting in L2 - leading to a huge thread of high level evaluations into the engine and notional Mars rocket family, including a lot of renderings, and more to come.

L2 Members, start here - as this OP serves as a sub menu to key items:
http://forum.nasaspaceflight.com/index.php?topic=34145.0

NOTE: The graphics are notional, cropped from the great work by Dmitry Vorontsov in L2. SpaceX have not - to our knowledge - rendered graphics of the Mars Rockets/MCT, which is still *very* early in the planning process. We're being rocket fans and playing with the info Mr. Mueller noted. That will also foster a second article on the rocket/MCT at a later date.
« Last Edit: 10/04/2016 12:33 PM by Chris Bergin »

Offline Lars_J

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #1 on: 03/07/2014 05:07 PM »
A great article!

So just to be clear - "Full flow" = "staged combustion", as the article implies? Or is there something more to it?

Offline SpaceXFanMan

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #2 on: 03/07/2014 05:13 PM »
That wasn't just a cool read, it was an education! Thanks Alejandro! :)

Offline butters

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #3 on: 03/07/2014 05:16 PM »
A great article!

So just to be clear - "Full flow" = "staged combustion", as the article implies? Or is there something more to it?

Full-flow staged combustion (FFSC) means that all of the propellant flows through the preburners and turbines before entering the main combustion chamber. There is a fuel-rich preburner for the fuel turbopump and an oxidizer-rich preburner for the oxidizer turbopump. All propellants enter the main combustion chamber as gases (hence the "gas-gas" terminology).

The main advantages of FFSC over gas-liquid SC are that turbine inlet temperatures can be lower (because mass flow rate is higher) and/or chamber pressures can be higher. The design can be tuned to favor either low temps or high pressures. It appears that SpaceX is favoring low temps (i.e. reusability without exotic materials) for Raptor rather than shooting for a very high chamber pressure.

Offline rklaehn

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #4 on: 03/07/2014 05:16 PM »
A great article!

So just to be clear - "Full flow" = "staged combustion", as the article implies? Or is there something more to it?

If I understood it correctly, full flow is using staged combustion on both the fuel and the oxidizer size. So
- you take a small fraction of the fuel and burn it with all the oxidizer to drive one turbine
- and you also take a small fraction of the oxidizer and burn it with the all the fuel to drive another turbine

The end result is that every drop of propellant goes through a turbine, hence "full flow". Another implication is that all propellants are gaseous once they enter the main combustion chamber, hence "gas/gas".
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Offline baldusi

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #5 on: 03/07/2014 05:18 PM »
Thanks Chris for giving me the opportunity to write on your site. You've been a wonderful editor and brought the best parts. BTW, those graphics are awesome. I can't believe I was part of this  :P

Offline Lars_J

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #6 on: 03/07/2014 05:18 PM »
Thanks, butters & rklaehn, that helps!

Offline Mark Max Q

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #7 on: 03/07/2014 05:24 PM »
Alejandro, that is what Chris would say is "meaty" work. Had no idea about the history, so interesting. LOVE that image of Korolev and Glushko....a picture that says a 1000 words.

Exciting times!

Online Elmar Moelzer

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #8 on: 03/07/2014 05:32 PM »
Great article Alejandro!

Offline DavidH

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #9 on: 03/07/2014 05:37 PM »
That wasn't just a cool read, it was an education! Thanks Alejandro! :)

Wow. Quite an education. Thanks. Love L2 for being able to watch this happen!


Are the legs scaled to the same ratio as the F9? The appear to barely be able to reach the ground from their mount points, much less be a stable base.
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Offline parham55

Great work baldusi!

Offline Jamziz

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #11 on: 03/07/2014 06:07 PM »
Fantastic article, excellent job.

I'll be holding my breath, waiting for news from the Raptor's R&D test program.

Offline Joffan

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #12 on: 03/07/2014 06:27 PM »
Nice work Alejo.

I got a little confused when you were telling us about the concepts presented in 2010, because I'm a skim-reader, so I forgot the context by the time you were talking about how troublesome liquid hydrogen is. :-)

The historical context of full-flow engines was fascinating.
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Offline Lobo

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #13 on: 03/07/2014 06:30 PM »
Very awesome article!

Offline baldusi

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #14 on: 03/07/2014 06:31 PM »
Alejandro, that is what Chris would say is "meaty" work. Had no idea about the history, so interesting. LOVE that image of Korolev and Glushko....a picture that says a 1000 words.
Pictures are all Chris. And as editor he changed some parts for clarity, fact-checked content and left some extra part for a possible future article. He's an Editor (with capital E) and this site excellent record is all thanks to him. So while my name is up there, I see this more as a collaboration. He's humble and traditionally the editor don't always gets all the attribution they deserve.
Btw, some of the best read on the Korolev-Glushko break up can be read in Cherkov's "Rocket and the People vol 4". It's free from NASA's EBook section. The best public information on the RD-270 is on lrpe.de, but it's in Russian. Google Translate does a good consistent job, once you understand what it mistranslates, you can rely on that mistranslation  :P

Are the legs scaled to the same ratio as the F9? The appear to barely be able to reach the ground from their mount points, much less be a stable base.
Please understand that this is a notional drawing. But its done by an actual rocket designer. Until the full image is released, we can only follow this discussion on L2. But it does makes some sense.
You can do some back of the envelope numbers, though. The RD-191 nozzle is 1.5m wide, and supplies 1.9MN. So a 4.5MN should be something around 2.3m~2.5m nozzle diameter. The rest is left as an exercise to the reader  ;)

`
Nice work Alejo.

I got a little confused when you were telling us about the concepts presented in 2010, because I'm a skim-reader, so I forgot the context by the time you were talking about how troublesome liquid hydrogen is. :-)

The historical context of full-flow engines was fascinating.
Thanks! It's very difficult to make an article that flows, and gives information. But I think that this site is characterized exactly because articles add historical data to put each event into context. While doing research on engine cycles, I found that the full flow cycle is almost always seen as an academic concept, too expensive and risky to put into actual use. I wanted to transmit the boldness of SpaceX's move to develop such an engine. So I felt I needed to both talk about the (public) evolution of the Raptor project, at least as I live it, and of the engine cycle.
I tried to put all into a more general history of gas generator/preburner engines. But it got too big an, eventually boring. It simply didn't worked. That's why you need an Editor. In the end I'm very happy with how it turned out.
« Last Edit: 03/07/2014 06:37 PM by baldusi »

Offline Prober

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #15 on: 03/07/2014 06:37 PM »
Great work baldusi!

I 2nd that ;)
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Offline BrightLight

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #16 on: 03/07/2014 06:39 PM »
wow
gret article - SpaceX rises one more step - just super.

Offline punder

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #17 on: 03/07/2014 06:44 PM »
Yes okay, that was very tease-worthy.   ;D

I have Chertok's volumes on Kindle, so I will tackle them now.  I did read Asif Siddiqi's books--they are really good.

Thanks for an excellent article.

p.s. I am wearing my SpaceX McGregor t-shirt today.   8)
« Last Edit: 03/07/2014 06:50 PM by punder »

Offline brihath

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #18 on: 03/07/2014 07:04 PM »
Baldusi and Chris-

Excellent article, both from a history perspective and distilling Spacex's focus on evolutionary innovation, reliability and reusability.  I am looking forward very much to your report on the Raptor's first test run.  Mr. Musk's team continues to amaze me with what they have accomplished as a privately owned company.

Thanks again for a great article!

Online TomH

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #19 on: 03/07/2014 07:08 PM »
To quote my favorite Vulcan (one eyebrow rises) Fascinating.

Question: If SpaceX builds a this or any HLV, will NASA then be legally required to give up SLS and begin purchasing from SpaceX? Would it depend upon how far along they are with SLS? I could see certain senators wanting to protect SLS. With SpaceX costs being lower and the HLV all made in US, I could also see a lot of pressure to dump SLS. I wonder how many within NASA would want to preserve their HLV and how many would want to drop it in favor of the lower cost LV to enable payload/mission funding. Say SLS has flown 4 times and now needs RS-25e and possibly advanced boosters as well at the same time the new SpaceX HLV comes on line, SLS needs to move to a new block, yet its proponents are citing its performance record as evidence it should continue in a new block rather than being replaced by SX-HLV.

How do you see any or all of these scenarios playing out?
« Last Edit: 03/07/2014 07:35 PM by TomH »

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