Author Topic: SpaceX Engine Development  (Read 183427 times)

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
SpaceX Engine Development
« on: 05/30/2012 04:35 pm »
So lately there has been a good bit of head scratching on various papers and rumors that have come out over the last year and a half or so regarding spacex engine designs and possible planned new engines and a potential new line of falcon rockets.

I decided to move the ongoing discussion on this from the general discussion thread here, as this should have a thread of its own. Additionally this thread should act as the new (and current) thread regarding any new information that comes to light, such as updates press releases ect, regarding spyx engine development in the future.

Most recent paper I know of in which merlin2 as well as raptor were discussed in more detail was on June 28th 2010 per this thread:

1. http://forum.nasaspaceflight.com/index.php?topic=22395.0

There are additional threads related to this paper and some new information since then in the spacex section but the thread listed above has the most information.

M1D information can be found here, and is relevant as M2 would be based heavily on M1D: http://forum.nasaspaceflight.com/index.php?topic=26388.0


Additional thread which was one of the first to discuss Spyx studies into heavy lift, which came up during the HLLV study at NASA during the spaceflight policy fight:

3. http://forum.nasaspaceflight.com/index.php?topic=23464.0

And another thread discussing Falcon and Merlin derivatives and possible future engine design:

4. http://forum.nasaspaceflight.com/index.php?topic=27275.0;all


So thats basically a very brief and slight overview of previous discussion on this topic, and existing non-L2 based information on this topic.

Resuming from the previous thread with my latest write-up:



Quote
the problem there being that Merlin 2 costs a hell of a lot to develop for performance goals that have been largely achieved with Merlin 1D, and on top of that it's not compatible with SpaceX's vertical landing reusability architecture. Which, even if you don't credit it with high chances of success (can't blame you), is certainly a strong priority for SpaceX. They won't do anything that requires reusability, but at this point they won't do anything that precludes it.

Performance targets for the upgraded falcon 9 and FH which were planned anyway. M1D was always the plan. Merlin 2 would be for a larger falcon rocket, it would be based on the falcon 9 but likely would use only one merlin 2 on the first stage, and potentially raptor or a merlin2 based mvac on the second stage. So this would be a new rocket, not existing, and they would build it only if they believed they had a market for much larger payloads and/or more BEO payloads.


So lets try a hypothetical where they would build it. For example if an actual commercial market for BEO related activities comes into play in say 5 years,  and there is a need for lift to BEO. Then they would build it. Another scenario would be if it was determined that flying many moderate to heavy LEO payloads on a FalconX as opposed to a FH was cheaper (economy of scale maybe?) then they would build it.

Otherwise there is no use for FalconX so it will remain shelved.

As for Merlin2, there is a desire to try and reduce the number of engines on the FH. This is because it would appear that ultimately SpaceX wants to acquire government contracts for that vehicle for things that might normally fly on DIVH and/or things that are to heavy for that. The way things appear right now, the idea of having 27 engines be them 1c's or  1ds on your inital stage is probably a turn off to these sorts of contracts, because its not viewed as reliable, and indeed it remains to be seen if it will be reliable or not. 

So in order to make this more reliable, as well as easier to operate (IMO) Merlin2 would be desirable for the FH vehicle because you could, if it met the performance targets discussed in the 2010 papers, essentially use one on each CCB and attain more than enough thrust. It would also most likely boost the lift of FH considerably, especially if you retained CCB cross-feed.

In addition, m2 development is not as expensive as you seem to think, its essentially a scaled up version of the merlin1D so its really not an entirely new engine, just a larger one.

But whether they ultimately decide to do that in the near term is purely hypothetical. We will have to see what comes of merlin2.

Raptor also plays into that somewhat because it seems like the original intent (based on the 2010 papers anyway) was to replace MVAC on all vehicles with raptor. Most likely with 2 separate versions of raptor, one for F9 and on one for FH. Only real difference would be size, F9 version would probably be smaller as you don't need full capability from the engine for that vehicle (due to payload not being extremely heavy), and larger for FH since it would be flying the heavy payloads. That intent has changed however, because M1D+M1DVAC has more performance than I think was originally expected, so there is honestly not a huge need to phase out mvac (after all it has REALLY good isp for a hydrocarbon engine).

So as far as I can tell after looking into this raptor designs are made and are on the back-burner right now. They are still devoting a small team to it, likely because as we all know staged combustion hydro-lox engines are EXTREMELY hard to design. IMHO from a propulsion standpoint that's essentially "the" hardest challenge is designing a large hydrolox engine, particularly and upper stage engine that would need to be capable of multiple re-starts.


As to other propulsion projects, they are all shelved as far as I can tell because they have no need for things like methane engines, nuclear, ect unless they start doing large scale deep space missions to other planets. And that is many many MANY years off, if it ever happens.



So in summation:

Merlin2: Might be going forward in a limited capacity at a slow pace for future use on FH in place of 27 engines

Raptor: Back-burner, still in design SpaceX not sure if they still need it so minimal staff on it for design/concept study only.

Other propulsion systems: Besides draco 2 and re-usability related systems, all shelved or never went beyond concept study.


That I think is the most likely situation at this time regarding propulsion development at spacex.

And again, regarding the full re-usability stuff, I want to stress that I honestly do not think they will ultimately go forward with that once they discover how hard it is to fly back stages when testing begins later this year, if it begins this year that is.

Really not holding my breath as far as the whole "fly back on 3 merlins and land" story is concerned, that is going to be extraordinarily hard and quite expensive to pull off.




So thats where we left off. Looking forward to continuing this discussion.

Additionally, if you have additional information or documents regarding raptor, merlin2, or F-X, please post it here. I have had alot of trouble finding documents about this stuff and it would be really good to have more hard information on this topic, especially now considering the recent success of dragon.
« Last Edit: 05/30/2012 04:37 pm by FinalFrontier »
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline mr. mark

  • Full Member
  • ****
  • Posts: 1996
  • Liked: 172
  • Likes Given: 0
Re: SpaceX Engine Development
« Reply #1 on: 05/30/2012 04:54 pm »
As far as Grasshopper, you may be pleasantly shocked by what they accomplish. As far as future development, Musk has hinted openly at a nuclear based engine way off in the future. I think that's where they are ultimately going. Merlin 2 maybe, Raptor maybe but not likely.

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #2 on: 05/30/2012 05:03 pm »
As far as Grasshopper, you may be pleasantly shocked by what they accomplish. As far as future development, Musk has hinted openly at a nuclear based engine way off in the future. I think that's where they are ultimately going. Merlin 2 maybe, Raptor maybe but not likely.

Here is why I disagree.

Nuclear will not be needed until or unless there is a commercial business case for development/exploration to other planets. Otherwise that will be NASA's territory. It would also be ungodly expensive to develop a nuclear stage. So there is no reason to do that besides what you said, way off in the future.

As for raptor I think its actually got a 50/50 chance or better of going forward because it makes alot of sense in some respects. Especially if your going to be doing any sort of beo mission, it makes some sense to design a new upper stage capable of more prolonged operation and many more restarts then mvac for things like L1,L2 ect, and there is a potential buisness case to be made for commercial payloads there, in the near future (not at present however). Add to that it would seem to me there is a desire to have a more powerful and more versatile upper stage for FH in the future then simply an m1dvac or existing, I think there is some reason here to go forward with it.

But as of now, there is nothing concrete that beyond continuing concept study on the design, that it IS going forward. And that is one thing I am still trying to find out about. Takes time to run down information on that however since I don't have very large blocks of free time to devote to it. Once I get onto L-2 that should help.


As to the grasshopper I hope your right on that. 
« Last Edit: 05/30/2012 05:17 pm by FinalFrontier »
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline mr. mark

  • Full Member
  • ****
  • Posts: 1996
  • Liked: 172
  • Likes Given: 0
Re: SpaceX Engine Development
« Reply #3 on: 05/30/2012 05:24 pm »
Raptor could be next up for development, maybe. That's something we both can agree on. As far as Merlin 1d we've seen the tests and it seems to be coming along nicely. My thoughts are what to achieve AFTER Merlin 1d. SpaceX engineers are going to have some time on their hands after 1d is completed and in service. Let's hope they push the envelope.
« Last Edit: 05/30/2012 05:26 pm by mr. mark »

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 6334
  • Michigan
  • Liked: 4207
  • Likes Given: 2
Re: SpaceX Engine Development
« Reply #4 on: 05/30/2012 05:27 pm »
Nuclear won't be done without NASA involvement because it will likely also require the involvement of the Nuclear Regulatory Commission, and having dealt with them before I can guarantee they make NASA and the FAA look positively laissez faire. Best to go with high ISP uppers, depots and/or SEP if at all possible.
« Last Edit: 05/30/2012 05:30 pm by docmordrid »
DM

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #5 on: 05/30/2012 05:30 pm »
Raptor could be next up for development, maybe. That's something we both can agree on. As far as Merlin 1d we've seen the tests and it seems to be coming along nicely. My thoughts are what to achieve AFTER Merlin 1d. SpaceX engineers are going to have some time on their hands after 1d is completed and in service. Let's hope they push the envelope.

Regarding that here is page 12 from the 2010 documentation.

Shows some of the performance targets of the proverbial "next gen" falcons as well as a heavy lift option, all powered by merlin2.

It also shows a current falcon heavy with a merlin2 option instead of m1d.

« Last Edit: 05/30/2012 05:31 pm by FinalFrontier »
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline jnc

  • Full Member
  • **
  • Posts: 277
  • Yorktown, Virginia
    • Home page
  • Liked: 1
  • Likes Given: 0
Re: SpaceX Engine Development
« Reply #6 on: 05/30/2012 05:33 pm »
as we all know staged combustion hydro-lox engines are EXTREMELY hard to design. ... particularly and upper stage engine that would need to be capable of multiple re-starts.

Given that, any chance they'd 'buy in' an existing engine (even if they only buy the basic design, and develop/produce it themselves)?

Noel
"America Needs - Space to Grow"

(old bumper sticker)

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 6334
  • Michigan
  • Liked: 4207
  • Likes Given: 2
Re: SpaceX Engine Development
« Reply #7 on: 05/30/2012 05:35 pm »
Or, perhaps with partners and/or an equity firms involvement, buy a certain engine maker that's for sale?
DM

Offline ArbitraryConstant

  • Senior Member
  • *****
  • Posts: 2014
  • Liked: 628
  • Likes Given: 311
Re: SpaceX Engine Development
« Reply #8 on: 05/30/2012 05:36 pm »
Quote
the problem there being that Merlin 2 costs a hell of a lot to develop for performance goals that have been largely achieved with Merlin 1D, and on top of that it's not compatible with SpaceX's vertical landing reusability architecture. Which, even if you don't credit it with high chances of success (can't blame you), is certainly a strong priority for SpaceX. They won't do anything that requires reusability, but at this point they won't do anything that precludes it.

Performance targets for the upgraded falcon 9 and FH which were planned anyway. M1D was always the plan. Merlin 2 would be for a larger falcon rocket, it would be based on the falcon 9 but likely would use only one merlin 2 on the first stage, and potentially raptor or a merlin2 based mvac on the second stage.
Even assuming M2 gets built this makes no sense. If one M2 could get a rocket off the ground, then one M2 will give the upper stage a really bad mass fraction and way too much acceleration. It's bad engineering.

As for Merlin2, there is a desire to try and reduce the number of engines on the FH. This is because it would appear that ultimately SpaceX wants to acquire government contracts for that vehicle for things that might normally fly on DIVH and/or things that are to heavy for that. The way things appear right now, the idea of having 27 engines be them 1c's or  1ds on your inital stage is probably a turn off to these sorts of contracts, because its not viewed as reliable, and indeed it remains to be seen if it will be reliable or not.
This is a reasonable motivation for M2, however given the development costs quoted (~$1B) I recall SpaceX angling to get a government contract to develop the thing and I don't think they will without that. Being able to bid on more launches would be nice, however they're already booked solid and scrambling to fulfill the existing contracts. If they can deliver F9 reliably and on time, that'll carry them through the decade.

As a speculative venture, full reusability is a bigger deal long term than DoD launches, is something SpaceX is prepared to self-fund, is potentially achievable with variants of existing vehicles and engines, and is not well served by M2 because of the extremely large size.

In addition, m2 development is not as expensive as you seem to think
Markusic: "(Merlin 2) could be qualified in three years for $1 billion.".

The question then becomes why you think it's less expensive than SpaceX does - if they're wrong, it's probably in the other direction.

As to other propulsion projects, they are all shelved as far as I can tell because they have no need for things like methane engines, nuclear, ect unless they start doing large scale deep space missions to other planets.
The case for methane has at least as much to do with the favorable design attributes (similar density to LOX simplifying pumping, non-coking) as the ISP. It's a good fuel for a company without a big heritage investment.

And again, regarding the full re-usability stuff, I want to stress that I honestly do not think they will ultimately go forward with that once they discover how hard it is to fly back stages when testing begins later this year, if it begins this year that is.
That is entirely possible, but that's different than arguing they are prepared to commit to engines that will rule it out before this has been demonstrated. You think it won't work, and there's a good chance you're right, but as far as they're concerned Reusability Is The Goal. So they're not going to design engines around expendability. That's what you'd do with your view reusability won't work.

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #9 on: 05/30/2012 05:38 pm »


Here is a bit more information to help describe this.

From the same documentation, regarding design concept for merlin 2, raptor, and possible performance on an HLV (you must remember that at the time this was done, the space policy fight over HLV and everything else was in full swing).





3-30-2017: The start of a great future
"Live Long and Prosper"

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #10 on: 05/30/2012 05:39 pm »
as we all know staged combustion hydro-lox engines are EXTREMELY hard to design. ... particularly and upper stage engine that would need to be capable of multiple re-starts.

Given that, any chance they'd 'buy in' an existing engine (even if they only buy the basic design, and develop/produce it themselves)?

Noel


I suppose its quite possible. Doesn't seem likely considering they already devoted time to a design but who knows.
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline jnc

  • Full Member
  • **
  • Posts: 277
  • Yorktown, Virginia
    • Home page
  • Liked: 1
  • Likes Given: 0
Re: SpaceX Engine Development
« Reply #11 on: 05/30/2012 05:41 pm »
It would also be ungodly expensive to develop a nuclear stage.

Not only that, aren't nuclear engine heavy as heck - in addition to all the pipes, pumps etc that you have on a regular 'chemical' engine, you'd need a complete reactor? High ISP and high thrust, sure, but also heavy - not sure what the application is?

Noel
"America Needs - Space to Grow"

(old bumper sticker)

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6160
  • California
  • Liked: 677
  • Likes Given: 195
Re: SpaceX Engine Development
« Reply #12 on: 05/30/2012 05:46 pm »
as we all know staged combustion hydro-lox engines are EXTREMELY hard to design. ... particularly and upper stage engine that would need to be capable of multiple re-starts.

Given that, any chance they'd 'buy in' an existing engine (even if they only buy the basic design, and develop/produce it themselves)?

Very unlikely - and certainly not from any of the existing large engine producers like PwR. The cost is just too high - they can make it themselves for cheaper if needed.

Offline peter-b

  • Dr. Peter Brett
  • Full Member
  • ****
  • Posts: 651
  • Oxford, UK
  • Liked: 18
  • Likes Given: 74
Re: SpaceX Engine Development
« Reply #13 on: 05/30/2012 05:49 pm »
Hi FinalFrontier,

Thank you for this comprehensive post, because it provides an excellent context for discussion.

I think you're way off the mark with respect to Merlin 2, however.

Firstly, I think you underestimate the difficulty involved in building extremely large rocket engines. The published range of values for Merlin 2 sea level thrust would make it literally the largest and most powerful single-chamber gas generator rocket engine in history. The F-1 had massive problems achieving combustion stability, and there seems to be no evidence yet of a general solution to those difficulties.

Secondly, for SpaceX to move to Merlin 2 for a launcher similar in size to Falcon 9 would entail completely discarding engine-out capability. This would only provide an increase in reliability if the probability of a Merlin 2 failing was smaller than the probability of three or more Merlin 1s failing simultaneously.

Thirdly, if SpaceX wanted to do first stage flyback, this could not be achieved using a single Merlin 2 class engine.  Since they are clearly very serious about that technology and clearly do not share your scepticism, it would not make sense for them to be spending resources on Merlin 2.

Finally, Elon and Gwynne have mentioned engines/boosters under development in several interviews over the last couple of years, and in none of them have they even hinted or alluded to development of supermassive engines, and the presentation which introduced the Merlin 2 has been disavowed.

My conclusions are that it currently does not make good business sense to be working on Merlin 2; Merlin 2 does not fit into what we know about the current SpaceX business model and short term development plans going forward; there is no evidence to support the idea that Merlin 2 development is any more than a PowerPoint study. Overall, I believe that Merlin 2, if it has had any work done on it at all, exists only in concept and initial design calculations and sketches.

On to Raptor. I also strongly disagree with you about this. In my opinion, the evidence seems to suggest that Raptor and Superdraco are SpaceX's main engine development efforts at the moment.

Firstly, we know that SpaceX are working on a staged combustion engine of some sort. Elon has mentioned this in several interviews.

Secondly, we know this makes good business sense, since one of the obvious market drawbacks of Falcon 9 and Falcon Heavy is the relatively poor performance to GTO and deep space trajectories due to the limited Isp of the gas generator Merlin Vacuum engine. Since SpaceX has deep space ambitions, a more efficient upper stage engine seems like a logical next step, and wouldn't hurt the LEO performance either.

Thirdly, we know that SpaceX are working on a methane engine from published correspondence with DoD. Note that a staged combustion methane/oxygen engine could run fuel-rich while avoiding both the preburner coking problems and metallurgy problems associated with kerosene/oxygen. Also, liquid methane and liquid oxygen have similar storage requirements and temperatures, making methane quite a lot simpler and more practical to use than liquid hydrogen, which is notorious in terms of its handling difficulty. Furthermore, a methane engine makes good sense in terms of Mars applications, and there's an interview somewhere around in which Elon mentions fueling rockets using solar electricity to create fuel from atmospheric water and carbon dioxide.

My conclusions are that Raptor as a methane/oxygen fuel-rich staged combustion engine makes good sense as a next step from both engineering and business points of view, and its ongoing development seems to be substantiated by remarks made by Elon here and there.

In summary: Merlin 2 doesn't exist, and Raptor will be the next SpaceX engine design.
« Last Edit: 05/30/2012 06:01 pm by peter-b »
Research Scientist (Sensors), Sharp Laboratories of Europe, UK

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #14 on: 05/30/2012 05:55 pm »
Quote
the problem there being that Merlin 2 costs a hell of a lot to develop for performance goals that have been largely achieved with Merlin 1D, and on top of that it's not compatible with SpaceX's vertical landing reusability architecture. Which, even if you don't credit it with high chances of success (can't blame you), is certainly a strong priority for SpaceX. They won't do anything that requires reusability, but at this point they won't do anything that precludes it.

Performance targets for the upgraded falcon 9 and FH which were planned anyway. M1D was always the plan. Merlin 2 would be for a larger falcon rocket, it would be based on the falcon 9 but likely would use only one merlin 2 on the first stage, and potentially raptor or a merlin2 based mvac on the second stage.
Even assuming M2 gets built this makes no sense. If one M2 could get a rocket off the ground, then one M2 will give the upper stage a really bad mass fraction and way too much acceleration. It's bad engineering.

As for Merlin2, there is a desire to try and reduce the number of engines on the FH. This is because it would appear that ultimately SpaceX wants to acquire government contracts for that vehicle for things that might normally fly on DIVH and/or things that are to heavy for that. The way things appear right now, the idea of having 27 engines be them 1c's or  1ds on your inital stage is probably a turn off to these sorts of contracts, because its not viewed as reliable, and indeed it remains to be seen if it will be reliable or not.
This is a reasonable motivation for M2, however given the development costs quoted (~$1B) I recall SpaceX angling to get a government contract to develop the thing and I don't think they will without that. Being able to bid on more launches would be nice, however they're already booked solid and scrambling to fulfill the existing contracts. If they can deliver F9 reliably and on time, that'll carry them through the decade.

As a speculative venture, full reusability is a bigger deal long term than DoD launches, is something SpaceX is prepared to self-fund, is potentially achievable with variants of existing vehicles and engines, and is not well served by M2 because of the extremely large size.

In addition, m2 development is not as expensive as you seem to think
Markusic: "(Merlin 2) could be qualified in three years for $1 billion.".

The question then becomes why you think it's less expensive than SpaceX does - if they're wrong, it's probably in the other direction.

As to other propulsion projects, they are all shelved as far as I can tell because they have no need for things like methane engines, nuclear, ect unless they start doing large scale deep space missions to other planets.
The case for methane has at least as much to do with the favorable design attributes (similar density to LOX simplifying pumping, non-coking) as the ISP. It's a good fuel for a company without a big heritage investment.

And again, regarding the full re-usability stuff, I want to stress that I honestly do not think they will ultimately go forward with that once they discover how hard it is to fly back stages when testing begins later this year, if it begins this year that is.
That is entirely possible, but that's different than arguing they are prepared to commit to engines that will rule it out before this has been demonstrated. You think it won't work, and there's a good chance you're right, but as far as they're concerned Reusability Is The Goal. So they're not going to design engines around expendability. That's what you'd do with your view reusability won't work.



1.
Quote
The question then becomes why you think it's less expensive than SpaceX does - if they're wrong, it's probably in the other direction.

I do think it may be less expensive now, as Merlin 1 d is built and the design for Merlin 2 may have changed to reflect that. Also I think that may have been on the high side, but I could be wrong.  As far as res-usability, on this engine (if it was in fact 1.3 bil.) then it would make more sense to recover the first stage and re-use it. But I still don't see how flying the stage back makes more sense from a cost and complexity stand point then using parachutes (which they never managed to do properly).  For the FX or whatever rocket would be using Merlin 2, it would make sense to re-use it. But for the exist vehicles using Merlin1c and soon Merlin1d, I think it will not be cost effective. We will see what happens when they start testing but once again I say, I am not holding my breath on re-usability, at least for the existing LV family, if the new vehicles discussed here were ever built then it would be a different story due to size and expense.


2.
Quote
As a speculative venture, full reusability is a bigger deal long term than DoD launches, is something SpaceX is prepared to self-fund, is potentially achievable with variants of existing vehicles and engines, and is not well served by M2 because of the extremely large size.

I would argue somewhat the opposite as far as M2 is concerned. While again, it would not make sense to fly-back a booster that size it would make sense to do parachute recovery as was originally intended for all falcon 9 first stages anyway. Remeber, large though it may be in terms of thrust, in terms of physical size m2 would be a good deal smaller then F1. There would also be only one per stage.

Re-usability all depends on what system you are using to return the stage to earth. If its parachute/splashdown its considerably less complex (and therefore less expensive when taken together with refurbishment costs) then trying to retro brake and retro land a stage by restarting first stage engines, which is apparently what they want to do with Falcon 9 now. That certainly would not make sense for something the size of Merlin, but simply junking something the size of Merlin 2 (based on expense) would make even less sense so parachute it.

And once again, IMO they are going to find flyback for the Falcon 9 first stage much harder then they think.

3.
Quote
Even assuming M2 gets built this makes no sense. If one M2 could get a rocket off the ground, then one M2 will give the upper stage a really bad mass fraction and way too much acceleration. It's bad engineering.

Agreed, meant to put M1Dvac there not M2vac was a typo. But that would be the option only if they didn't build raptor, and it wouldn't make alot of sense to try and do both simultaneously unless they were sure there was a market, or was about to be a market for them.


4.
Quote
That is entirely possible, but that's different than arguing they are prepared to commit to engines that will rule it out before this has been demonstrated. You think it won't work, and there's a good chance you're right, but as far as they're concerned Reusability Is The Goal. So they're not going to design engines around expendability. That's what you'd do with your view reusability won't work.


Once again its all about HOW you return the stage to earth. And once again your correct, flyback would not make sense for an M2 stage. But M2 is not built and is potentially not even in development yet (beyond design of course) therefore it makes sense to focus on fly back for Falcon 9 now, if fly back is what you want to do for your vehicle[/b], but once again, I think that after they start testing those systems and discover how expensive and difficult that actually is they may change their mind and focus on trying to parachute the thing again.

And IMO it would have been better to actually recover a falcon 9 stage via a functioning parachute system prior to announcing your going to try building a fly back system, seems like the goal ought to have been actually recovering one of the things and refurbishing and re-using the engines so that you could have some confidence that you know how to do it. They have not done that yet, first two attempts failed apparently due to entry issues on the first stage, never made it to the parachute portion of the flight, but that doesn't mean they won't try it again.

« Last Edit: 05/30/2012 06:24 pm by FinalFrontier »
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #15 on: 05/30/2012 06:00 pm »
Quote
Firstly, I think you overestimate the difficulty involved in building extremely large rocket engines. The published range of values for Merlin 2 sea level thrust would make it literally the largest and most powerful single-chamber gas generator rocket engine in history. The F-1 had massive problems achieving combustion stability, and there seems to be no evidence yet of a general solution to those difficulties.

Hello, glad you like the thread.

Regarding the above, I think you mean understate ;)

The thing about it is merlin2 would not be a totally new engine, the intent seems to be to scale it up from merlin1D and that would make it quite a bit easier then trying to design something totally new, as for example the F1 was.

But that doesn't mean it wouldn't be difficult.

Regarding your other comments, on Merlin2 existing, I never said it existed yet, on the contrary I said it doesn't exist yet beyond the design stage, but the purpose of this thread is to discuss what its uses might be, what Spacex had said in the past about using it and on what, and if there was evidence that it had moved forward beyond design, which so far there is not.

The same is true of raptor, but if you have newer documentation suggesting that its moved forward (beside the LH2 tank car thing at the test site) then please post it, as that's the whole point of thread: trying to find out if it went forward or not.
« Last Edit: 05/30/2012 06:00 pm by FinalFrontier »
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #16 on: 05/30/2012 06:02 pm »
It would also be ungodly expensive to develop a nuclear stage.

Not only that, aren't nuclear engine heavy as heck - in addition to all the pipes, pumps etc that you have on a regular 'chemical' engine, you'd need a complete reactor? High ISP and high thrust, sure, but also heavy - not sure what the application is?

Noel



Yes, uranium is very dense and very heavy in terms of mass.
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline peter-b

  • Dr. Peter Brett
  • Full Member
  • ****
  • Posts: 651
  • Oxford, UK
  • Liked: 18
  • Likes Given: 74
Re: SpaceX Engine Development
« Reply #17 on: 05/30/2012 06:08 pm »
Regarding the above, I think you mean understate ;)
Thanks, I edited it.
The same is true of raptor, but if you have newer documentation suggesting that its moved forward (beside the LH2 tank car thing at the test site) then please post it, as that's the whole point of thread: trying to find out if it went forward or not.
See Elon's AIAA conference keynote address in August 2011 (). He said that he expected to unveil a "super-efficient" staged combustion engine "later this year or next year".

I don't think that the LH2 tank car at the test site can be taken as evidence that SpaceX are doing anything with LH2.
Research Scientist (Sensors), Sharp Laboratories of Europe, UK

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #18 on: 05/30/2012 06:16 pm »
as we all know staged combustion hydro-lox engines are EXTREMELY hard to design. ... particularly and upper stage engine that would need to be capable of multiple re-starts.

Given that, any chance they'd 'buy in' an existing engine (even if they only buy the basic design, and develop/produce it themselves)?

Very unlikely - and certainly not from any of the existing large engine producers like PwR. The cost is just too high - they can make it themselves for cheaper if needed.

If its staged combustion? That's where the question mark here is. But they have faced that sort of challenge before I suppose.

It wouldn't really be their policy to buy something like that out of house.
3-30-2017: The start of a great future
"Live Long and Prosper"

Offline FinalFrontier

  • Senior Member
  • *****
  • Posts: 4490
  • Space Watcher
  • Liked: 1332
  • Likes Given: 173
Re: SpaceX Engine Development
« Reply #19 on: 05/30/2012 06:18 pm »
Regarding the above, I think you mean understate ;)
Thanks, I edited it.
The same is true of raptor, but if you have newer documentation suggesting that its moved forward (beside the LH2 tank car thing at the test site) then please post it, as that's the whole point of thread: trying to find out if it went forward or not.
See Elon's AIAA conference keynote address in August 2011 (). He said that he expected to unveil a "super-efficient" staged combustion engine "later this year or next year".

I don't think that the LH2 tank car at the test site can be taken as evidence that SpaceX are doing anything with LH2.

Thank you for that link I hadn't seen it. And I agree with you on the tank car thing that was in fact my point, because some people have been speculating that it means that raptor is nearly complete, the problem is there is no other evidence to support that.

1 tank car does not a staged combustion hydrolox engine make.

FWIW: remember, raptor would be a hydrolox not a staged kerolox engine (according to papers anyway).
3-30-2017: The start of a great future
"Live Long and Prosper"

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0