Author Topic: SpaceX advances drive for Mars rocket via Raptor power  (Read 666675 times)

Offline TomH

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #540 on: 03/02/2015 10:18 pm »
However, I agree that once BFR is flying or perhaps even when it's late into development and looking "inevitable" with metal being bent and Raptor firing properly...that SLS main supporting argument that it's the only LV with that capacity, and that capacity is necessary for BLEO HSF pretty much goes away.  Then I think it'll be cancelled after just a few launches...

One would think so. But then again there's that little cadre of senators holding committee chairmanships. I think your scenario will happen if they're retired by then. If they all pull a Strom Thurmond and stay until they're centenarians, SLS may well continue receiving its welfare payments.

Offline CuddlyRocket

Off-the-wall thought - SpaceX take up BE-4 instead of developing Raptor.

cheers, Martin

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Offline Lobo

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #542 on: 03/03/2015 12:32 am »
However, I agree that once BFR is flying or perhaps even when it's late into development and looking "inevitable" with metal being bent and Raptor firing properly...that SLS main supporting argument that it's the only LV with that capacity, and that capacity is necessary for BLEO HSF pretty much goes away.  Then I think it'll be cancelled after just a few launches...

One would think so. But then again there's that little cadre of senators holding committee chairmanships. I think your scenario will happen if they're retired by then. If they all pull a Strom Thurmond and stay until they're centenarians, SLS may well continue receiving its welfare payments.

You have a point, but I think if those fossils are still there then, their hold won't be enough.  Questions will be asked that currently can be explained away by saying, "There's no LV that can come close to what SLS (or Ares V SDHLV) can do, and near 130mt to LEO is what's necessary for going to BLEO destinations with astronauts.  Multiple launch missions with smaller LV's introduces unacceptable level of LOM risk with their complexity.  A single LV of this class is necessary for a safe and robust exploration future...etc. etc.".

You can disagree with that assessment, but the fact is there is no other system that can do what SLS will and it's a he said/she said argument on whether that is -really- needed.  But "conventional wisdom" says it is and so that's the view you have to dislodge.
A BFR advocate will be able to say, "Yes, you are quite right.  Fortuantely now there is a lower cost alternative with the capacity equal (or in excess) of SLS.  With the money saved from it we can launch more payloads and have more missions and do more exploration.  NASA is relieved from having to maintain the overhead of a HLV themselves, etc. etc".

It'll be man-rated, so that argument is out.  And while cancelling SLS will mean cutting jobs in certain places, it'll mean creating new jobs in other places to support BFR.  So there will be those who'll fight those fighting to keep SLS.

Finally, NASA itself could be an X-factor.  I think there will be those who think they have a better shot of walking on MArs with SpaceX than with SLS, and will start saying so to Congress.  At the end of the day...NASA really would like to have their astros be the first to walk on Mars and worry that their current trajectory puts them in the same holding pattern they've been in for the last decade.

So we'll see.  But I think the fossils days will be numbered at that point, IMHO.


Offline Owlon

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #543 on: 03/03/2015 01:21 am »
Wouldn't it be ironic if SpaceX's Raptor-powered rocket led to SLS being cancelled, which led to the same bigger-is-better logic being applied to, say, a 500 ton to LEO NASA rocket that costs even more?

Offline su27k

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #544 on: 03/03/2015 01:54 am »
Two 500,000 lbf Raptors could be a replacement for the RD-180 on the Atlas-V.

I guess you missed the BE-4 announcement. ;)

Off-the-wall thought - SpaceX take up BE-4 instead of developing Raptor.

cheers, Martin

More off-the-wall thought: Re-engine SLS core stage using BE-4. (Did someone do the math about this before?)

Offline Brovane

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #545 on: 03/03/2015 02:26 am »
Does anyone know what is happening here?  Wikipedia said they upgraded the metholox engine to 1 million lbs thrust and speculation is for a 10m rocket with 9 of these engines for 9 million lbs thrust.  This update said February 2015.  Also does anyone have a time frame for this to come about?  Would it be before SLS is ready?

In a recent reddit appearance Musk said they're downsizing Raptor to 500,000 lbf

I don't bet against SpaceX producing anything as quickly as they want to.

Two 500,000 lbf Raptors could be a replacement for the RD-180 on the Atlas-V.

I guess you missed the BE-4 announcement. ;)

Off-the-wall thought - SpaceX take up BE-4 instead of developing Raptor.

cheers, Martin

Or SpaceX gets the USAF contract to develop a new engine that Congress wants in addition to the BE-4.   The USAF pays to finish the development of a Raptor engine in the range of 500-600k lbf.  SpaceX gets one part of the US govt to pay to develop the engine for it's BFR and it can then have a rival HLV to NASA's SLS. 
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Offline Norm38

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #546 on: 03/03/2015 02:52 am »
Wouldn't it be ironic if SpaceX's Raptor-powered rocket led to SLS being cancelled, which led to the same bigger-is-better logic being applied to, say, a 500 ton to LEO NASA rocket that costs even more?

I would hope that NASA has learned the lesson of runaway scope creep by now.  And working with a contractor is a two-way street.  NASA can ask for anything, doesn't mean that SpaceX has to go along with it.  I don't think SpaceX is interested in getting bogged down with some boondoggle that they can't sell to anyone else and use for anything else.

If 500 ton to LEO happens, it'll happen due to true need.  Such as so many launches of 100 ton class rockets are happening, docking payloads in LEO, that it's more efficient to launch more highly integrated and functional 500 ton blocks. 

So for the next decade, no.

Offline kch

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #547 on: 03/03/2015 03:27 am »

Without SLS, NASA BLEO HSF will pretty much be locked into SpaceX. 

... which is pretty much where NASA LEO HSF is now with regard to the Russians -- why would they make *that* mistake again?  That's more than enough reason to continue SLS, even if SpaceX gave them a dozen free BFR flights.  No more "barrels and ankles" situations, thank-you-very-much!

So you are saying that the Geopolitical situation between SpaceX and America is going to deteriorate because of Elon Musks overwhelming ambition to conquer other nations? And this will cause Elon Musk to tell America to find a trampoline? Yea that will happen... [/sarcasm]

LMAO ... no.  Nice try, but no.  Once NASA is "over a barrel" (wrt Russia, or SpaceX, or *any* potential-monopoly supplier), the price goes up....

... up higher even than NASA's own SLS pricing?  That's a lot of up.

Yes, it is.  For comparison: 

* what was the price of a Soyuz seat just before the Shuttles stopped flying?
* what is the price of a Soyuz seat now?

That's been a fair bit of up, too, has it not?

Offline Robotbeat

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #548 on: 03/03/2015 03:29 am »
There are laws preventing ripping off the government. Doesn't mean costs don't grow, but it will not exceed SLS.
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Offline kch

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #549 on: 03/03/2015 03:37 am »
There are laws preventing ripping off the government. Doesn't mean costs don't grow, but it will not exceed SLS.

Very glad to hear that.  :)

Offline meekGee

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #550 on: 03/03/2015 06:18 am »
The one thing to bring into consideration is that unlike all the other scenarios, SpaceX's own plans are much larger than any that the government has in mind.

If NASA says "never mind SLS, we'll fly with BFR" it won't make much difference to BFR, financially.  However, SpaceX will be more than happy to gain from NASA's other resources, and given SpaceX's plan, there's a large multiplier there.

So it's in their interest to serve as the heavy lift provider for NASA, and not in their interest to jack up pricing the minute they can. They are not a near-sighted company.
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Offline The Amazing Catstronaut

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #551 on: 03/03/2015 07:42 am »
The one thing to bring into consideration is that unlike all the other scenarios, SpaceX's own plans are much larger than any that the government has in mind.

If NASA says "never mind SLS, we'll fly with BFR" it won't make much difference to BFR, financially.  However, SpaceX will be more than happy to gain from NASA's other resources, and given SpaceX's plan, there's a large multiplier there.

So it's in their interest to serve as the heavy lift provider for NASA, and not in their interest to jack up pricing the minute they can. They are not a near-sighted company.

Agreed. In addition, it's always been in their ethos to try and appear to be as transparent a contractor as possible in the past - I'm not sure they'd mess around with that when conducting a project as high risk as BFR is.
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Offline baldusi

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #552 on: 03/03/2015 01:28 pm »
It's all in the contracting. If you get a Not To Exceed pricing contract for the next 20 years, like the OSP, or NLS II, then it's not that bed. The danger is on the re-negotiation.
On the other hand, the real cost of BEO won't be the launchers, but the payload. And the 3B/yr of SLS infrastructure could pay for a lot of mission.
Regarding the Raptor, the 230tnf reusable CH4/LOX seems to be the choice of Blue Origin (BE-4) and KBKhA and RSc Progress (RD-0162/4) have the same size and propellant. The BE-4 is ORSC, and so is the RD-0162/4, but they also use the expander cycle on the CH4 side, so it's actually a gas-gas injector.
Raptor, being full staged, should probably have the best performance, or ridiculous reusability. But nothing that they make can't be sort of replicated with the other two engines. And that's where it gets interesting. If SpaceX can solve the economic reusability problem of Mars transport, ULA/BO and KBKhA/RSC Progress could also do it in less than a decade (six to seven years if propulsion is a known quantity and money flows). And that's the point where SLS or any NASA owned SHLV had no meaning.

Offline starsilk

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #553 on: 03/03/2015 01:36 pm »
Or SpaceX gets the USAF contract to develop a new engine that Congress wants in addition to the BE-4.   The USAF pays to finish the development of a Raptor engine in the range of 500-600k lbf.  SpaceX gets one part of the US govt to pay to develop the engine for it's BFR and it can then have a rival HLV to NASA's SLS.

Ahh. Perhaps that is the deal that seems to have occurred regarding the block buy... leave it alone and USAF will fund raptor development.

Offline FinalFrontier

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #554 on: 03/03/2015 01:37 pm »
Potentially worth noting here. MCT (unless I am mistaken) which we often refer to as BFR is (as designed I think) more powerful than SLS. Even with the advanced booster, an extra RS25 (5 engine core) and a j2x upper stage (which is shelved at present) I believe SLS even in Block 3 territory only gets up around what, 150 mt? maybe? If the numbers are right on BFR it likely would be that powerful in its block one design. Engine improvements, iterative design improvements, could make it even stronger. And its not hard to see this actually, BFR as a design is much better than SLS and less complex purely from a technical standpoint. The single biggest advantage is the methane fuel supply instead of LH2. Methane is extremely energetic as a fuel, there is a massive surplus of it worldwide at present (gas wells are shut in due to over production) so its very VERY cheap to get, compared to LH2 which is quite expansive, and it should have more reaction mass per kg for a from sea level launch. Therefore you can, in theory, get more power out of a methane engine than both RP1 and LH2. For in vacuum flight, and this depends highly on engine design, its theoretically possible to get a greater ISP out of it than a comparable LH2 engine, purely due to the reason that some of your engine and tank-age components do not need to be quite as hardy when dealing with liquid methane, due to temperature constraints. Correct me if I am wrong but I believe LH2 is significantly colder than liquid methane.

In any case much of this is either in the design or theoretical realm right now as none of these things have been tried yet, let alone for a full flow stage combustion configuration, I don't believe anyone has ever tried that with a methalox engine. But the potential gains here are enormous, I think you can easily make something more powerful than most of the SLS designs in your first go around and potentially more reliable as well, and I am a shuttle and shuttle hardware lover saying that.
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Offline dglow

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #555 on: 03/03/2015 02:00 pm »
And its not hard to see this actually, BFR as a design is much better than SLS and less complex purely from a technical standpoint. The single biggest advantage is the methane fuel supply instead of LH2.

BFR's biggest advantage will be reuse and, therefore, flight rate.
The choice of fuel is most important to MCT – the part that travels to Mars – since it enables refuel and return (and therefore reuse, flight rate).

Offline S.Paulissen

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #556 on: 03/03/2015 02:18 pm »
Potentially worth noting here. MCT (unless I am mistaken) which we often refer to as BFR is (as designed I think) more powerful than SLS. Even with the advanced booster, an extra RS25 (5 engine core) and a j2x upper stage (which is shelved at present) I believe SLS even in Block 3 territory only gets up around what, 150 mt? maybe? If the numbers are right on BFR it likely would be that powerful in its block one design. Engine improvements, iterative design improvements, could make it even stronger. And its not hard to see this actually, BFR as a design is much better than SLS and less complex purely from a technical standpoint. The single biggest advantage is the methane fuel supply instead of LH2. Methane is extremely energetic as a fuel, there is a massive surplus of it worldwide at present (gas wells are shut in due to over production) so its very VERY cheap to get, compared to LH2 which is quite expansive, and it should have more reaction mass per kg for a from sea level launch. Therefore you can, in theory, get more power out of a methane engine than both RP1 and LH2. For in vacuum flight, and this depends highly on engine design, its theoretically possible to get a greater ISP out of it than a comparable LH2 engine, purely due to the reason that some of your engine and tank-age components do not need to be quite as hardy when dealing with liquid methane, due to temperature constraints. Correct me if I am wrong but I believe LH2 is significantly colder than liquid methane.

In any case much of this is either in the design or theoretical realm right now as none of these things have been tried yet, let alone for a full flow stage combustion configuration, I don't believe anyone has ever tried that with a methalox engine. But the potential gains here are enormous, I think you can easily make something more powerful than most of the SLS designs in your first go around and potentially more reliable as well, and I am a shuttle and shuttle hardware lover saying that.

The cost of the fuel itself is a rounding error in the cost of launch of such a large rocket.  Also,you're also confusing natural gas and methane.  Natural gas is what comes out of the ground and it's not pure methane, it needs to be processed to be methane.  The cost savings come from ease of ground handling, not the cost of the fuel. 

You then state that you have more reaction mass per kilogram, which is incorrect as, mass is mass, there is no way to make 1kg less than 1kg in a chemical reaction.  Perhaps you meant with increased tankage mass for the less dense hydrogen fuel that you mention a little later?  Please clarify.

If you build an engine poorly you could get worse ISP out of an ion motor than an Estes model rocket motor.  I'm unsure of the point you're trying to make.  The upper bound is dictated by reactant chemical energy, which is higher with LH2 than with CH4.  If you're talking impulse density factoring in tankage it's a muddier topic.  I don't mean to pick on you, I just hope you'll write with a little more specificity in the future so I, and others, aren't tempted to tear into you for inaccuracies.  :)

The only full flow engine demonstrated was the RD-280 and managed 301s ISP from hypergols.  AJR was working on the powerhead but I don't know if they ever had a working model.
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Offline FinalFrontier

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #557 on: 03/03/2015 03:37 pm »
Quote
The cost of the fuel itself is a rounding error in the cost of launch of such a large rocket.  Also,you're also confusing natural gas and methane.  Natural gas is what comes out of the ground and it's not pure methane, it needs to be processed to be methane.  The cost savings come from ease of ground handling, not the cost of the fuel. 
Minimal processing (if any) when compared to cracking needed to get sufficient quantities of  hydrogen for LH2. Not sure about this for raptor itself, but it is likely possible to build an engine that runs on simple liquefied natural gas or liqueifed petroleum gas. Thats another topic though.  Also (forgot this in my post), yes re-usability is a huge advantage.
Quote
You then state that you have more reaction mass per kilogram, which is incorrect as, mass is mass, there is no way to make 1kg less than 1kg in a chemical reaction.  Perhaps you meant with increased tankage mass for the less dense hydrogen fuel that you mention a little later?  Please clarify.
Correct I am wrong. Meant more btu/thermal equivalent energy per mass.However, even on that I am not sure off the top of my head if hydrogen has a higher upper bound per btu/mass equivalent than CH4 as you state later on. I will check on this because I am curious now. It would sort of surprise me but maybe it shouldn't. But wrt tankage yes  that is correct, you see possible improvements due to not needing tanks as large/complex as for LH2 due to density (and temperatures).
Quote
If you build an engine poorly you could get worse ISP out of an ion motor than an Estes model rocket motor.  I'm unsure of the point you're trying to make.  The upper bound is dictated by reactant chemical energy, which is higher with LH2 than with CH4.  If you're talking impulse density factoring in tankage it's a muddier topic.  I don't mean to pick on you, I just hope you'll write with a little more specificity in the future so I, and others, aren't tempted to tear into you for inaccuracies.
Reactant energy may be higher with LH2 however I was referring to both tankage AND to the mass of the engine itself. May be apples to oranges but consider the mass of an RS25 and the fact that to operate this engine must use two turbopumps for each component (LOX and LH2) where as a comparable methalox may function properly with unified pumps. Other components such as injectors ect, may save mass by virtue of the fuel the engine is designed for. Make your engine lighter you see performance improvements. But it is a muddy topic, however my general point is this particular engine is likely to more shall we say "optimize-able" as is the vehicle as compared to an LH2 core vehicle (at least wrt sea level launches).
Quote
The only full flow engine demonstrated was the RD-280 and managed 301s ISP from hypergols.  AJR was working on the power-head but I don't know if they ever had a working model.
True but this was hypergolics. My point was, not sure of any previous full flow design for methalox.

« Last Edit: 03/03/2015 05:25 pm by Galactic Penguin SST »
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Offline spacenut

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #558 on: 03/03/2015 03:45 pm »
This is what I think may happen.  SpaceX builds an 8m core rocket with about 5-5.5 million lb thrust which can deliver about 75 tons to LEO (next step up from F9H + wider loads).  A three core heavy version of the 8m rocket might deliver 200+ tons to LEO.  This trumps SLS and gives a smaller more usable single core rocket for deep space probes greater than F9H can deliver. 

Now he might build a 25 engine 10m core to do it all at once.  I think it would be more flexible with the smaller core.   

Offline FinalFrontier

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #559 on: 03/03/2015 03:52 pm »
This is what I think may happen.  SpaceX builds an 8m core rocket with about 5-5.5 million lb thrust which can deliver about 75 tons to LEO (next step up from F9H + wider loads).  A three core heavy version of the 8m rocket might deliver 200+ tons to LEO.  This trumps SLS and gives a smaller more usable single core rocket for deep space probes greater than F9H can deliver. 

Now he might build a 25 engine 10m core to do it all at once.  I think it would be more flexible with the smaller core.   

Worth noting several people did impromptu calculations based on some of the available known specifications of raptor (as currently designed) on a 10M core vehicle and came up with "roughly" this:
10M core first stage return (partially reusable): 128mt-LEO Block 1 variant single core
10M core first stage expendable (no boost back): 150mt-LEO Block 1 variant single core.
This is worth noting, though remember these are very rough estimates because this would make even the first variant of this vehicle more powerful than most of the SLS variants let alone the Block 1 currently in development, ostensibly for much lower cost. And remember, this is only a single core. A  "ultra heavy" configuration using three 10 meter core vehicle in a FH style config would be significantly more powerful and, ostensibly, would not require major new design/production effort.

But this is all speculation. WRT the numbers if you want to learn more see L2.
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