Author Topic: SpaceX: Merlin 1D thread  (Read 520324 times)

Offline baldusi

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Re: SpaceX: Merlin 1D Updates thread
« Reply #400 on: 06/27/2012 04:44 pm »
SpaceX does seem to use metric for most things except engine thrust.
We don't know that. Only that they publish on lbf. The 140klbg does a very round 5.6MN, and the new 147klbf goes to almost exactly 3.8MN. I know that SpaceX has been known for some very generous rounding. But I suspect that internally they use metric exclusively. After all, Elon learned to use the metric system first.

Offline MikeAtkinson

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Re: SpaceX: Merlin 1D Updates thread
« Reply #401 on: 06/27/2012 04:44 pm »
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams

That seems to be a confirmation that the weight is ~485-490kg.

Assuming "ton" = "tonne" (or metric ton).

If ton = 2000 lbs, then half-a-ton is 455 kg! But I still think you're right - SpaceX does seem to use metric for most things except engine thrust.

cheers, Martin

But he isn't trying to be accurate here, look at the other side of the equation "several Hoover Dams" - hardly accurate is it. All we can say from this statement is that it is within maybe 10% of "half a ton" where ton could mean tonne.

Offline oldAtlas_Eguy

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Re: SpaceX: Merlin 1D Updates thread
« Reply #402 on: 06/27/2012 05:04 pm »
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams

That seems to be a confirmation that the weight is ~485-490kg.

Assuming "ton" = "tonne" (or metric ton).

If ton = 2000 lbs, then half-a-ton is 455 kg! But I still think you're right - SpaceX does seem to use metric for most things except engine thrust.

cheers, Martin

But he isn't trying to be accurate here, look at the other side of the equation "several Hoover Dams" - hardly accurate is it. All we can say from this statement is that it is within maybe 10% of "half a ton" where ton could mean tonne.

T/W of 150 with vac thrust of 161klbf makes the upper weight number of 488kg, 160 T/W would be 457kg, so the bounds on the weight seem to be
457kg < engine weight < 488kg.

Stating that the T/W is more than 150 but not saying more than 160 means that it is somewhere between those two, possibly the upper value is 155 if rounding is used. 2 digit accuracy values.

Offline Robotbeat

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Re: SpaceX: Merlin 1D Updates thread
« Reply #403 on: 06/27/2012 06:46 pm »
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?

Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.
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Offline baldusi

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Re: SpaceX: Merlin 1D Updates thread
« Reply #404 on: 06/27/2012 07:03 pm »
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?

Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.
From what I've seen explained, the SC engine needs higher strength (due to higher temperature and pressure), but uses smaller diameter diameters, for equal thrust. And since you have the material (i.e. weight) needs decreasing cubically but diameters only decrease to the square, it's quite possible that you'll end up pretty close.
Let's remember that the NK-33 is a 45 years old engine. And still it's 130T/W vs more then 150T/W for the Merlin 1D. I don't know if you could apply some tricks of the Merlin 1D to improve the T/W of the NK-33. But I guess it's not necessary impossible to get similar (say, 10%) T/W. How much T/W (and thus fmp) are you willing to sacrifice for the increased isp, that depends heavily on your overall requirements.
What I can say, is that SC is a lot more expensive to develop than GG.

Offline MP99

Re: SpaceX: Merlin 1D Updates thread
« Reply #405 on: 06/27/2012 07:16 pm »
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?

Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.

From what I've seen explained, the SC engine needs higher strength (due to higher temperature and pressure), but uses smaller diameter diameters, for equal thrust. And since you have the material (i.e. weight) needs decreasing cubically but diameters only decrease to the square, it's quite possible that you'll end up pretty close.
Let's remember that the NK-33 is a 45 years old engine. And still it's 130T/W vs more then 150T/W for the Merlin 1D. I don't know if you could apply some tricks of the Merlin 1D to improve the T/W of the NK-33. But I guess it's not necessary impossible to get similar (say, 10%) T/W. How much T/W (and thus fmp) are you willing to sacrifice for the increased isp, that depends heavily on your overall requirements.
What I can say, is that SC is a lot more expensive to develop than GG.

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Offline mvpel

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Re: SpaceX: Merlin 1D Updates thread
« Reply #406 on: 06/28/2012 03:26 am »
The statement that the previous method was plating makes me more curious. It implies that the channels in the 1C chamber/nozzle are on the *inside* face of the central layer. If they were on the outside, then the plating process would just fill in the channels, instead of leaving them open.

I don't expect all these details to be known, tbh. I doubt SpaceX wants to share every last detail of their manufacturing process with their competitors.

Check out patent 5,473,817, by Schnoor and Surls of United Technologies. It describes the technique for explosive forming of combustion chamber cooling channels quite nicely. It makes reference to another patent, 3,208,132, which describes an explosive forming/brazing process, but the newer patent eliminates the need for brazing or welding. You form the outer wall by filling the outside channels with wax, leaving the ridges exposed, then electro-forming the outer surface onto the ridges. Once you melt out the wax, you have your fully formed coolant channels.
« Last Edit: 06/28/2012 03:30 am by mvpel »
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Offline dwightlooi

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Re: SpaceX: Merlin 1D Updates thread
« Reply #407 on: 06/28/2012 04:53 am »

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Before we even talk about the performance benefits of a Staged Combustion cycle and if it decreases reliability and safety margins, I think we should why we want to totally change the design of the Merlin in exchange for about 20 Isp. In short, why do we want more performance?

The F9 already has payload capacity of the EELVs. The FH already beats them by a factor of 2. That 20 Isp may get you another 2 tons of lift in an F9 and up to 5 on the FH. Really, does have 15 tons instead of 13 and/or 58 instead of 53 help SpaceX expand their launch manifest in any tangible way? If not, why isn't a simpler, safer, cheaper to build engine preferable to one with higher performance?

Offline CapitalistOppressor

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Re: SpaceX: Merlin 1D Updates thread
« Reply #408 on: 06/28/2012 10:27 am »

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Before we even talk about the performance benefits of a Staged Combustion cycle and if it decreases reliability and safety margins, I think we should why we want to totally change the design of the Merlin in exchange for about 20 Isp. In short, why do we want more performance?

The F9 already has payload capacity of the EELVs. The FH already beats them by a factor of 2. That 20 Isp may get you another 2 tons of lift in an F9 and up to 5 on the FH. Really, does have 15 tons instead of 13 and/or 58 instead of 53 help SpaceX expand their launch manifest in any tangible way? If not, why isn't a simpler, safer, cheaper to build engine preferable to one with higher performance?


This post is OT, as pointed out by Martin, but as long as we are living dangerously . . .

The "New Methane SC" thread discusses this issue exhaustively while making a persuasive case that the proposed SC engine will burn CH3.

http://forum.nasaspaceflight.com/index.php?topic=26995.0

First of all, Elon has said that he is getting ready to announce a new high efficiency SC engine, so as is normally the case what we think he should do doesn't matter.  If you take him at his word he is working on an SC engine for something.

Second, SPX answered an Air Force RFP with a proposal for a Methane powered high performance engine that they were working on, and which also could be a SC engine.

Third, SPX launchers would all get a big performance increase GTO and BEO with a high isp vac stage.  What you think SPX needs is not what Elon thinks it needs.  Elon badly wants to retire on Mars.  He is not doing that with a M1d vac upper stage.

Fourth, its not clear at all that you achieve only a 20isp improvement with a CH4 SC engine.  Threadstimates range up to a nigh impossible 400isp for vac operations, but a lot of smart money thinks 380 vac looks achievable along with a 355ish first stage.

Fifth, a lot of thread guesstimates point to the re-usability advantages of a CH4 SC engine in the context of Grasshopper.  Recent Russian test data support this line of thinking.  Elon <3's re-usability, because once he retires on Mars he wants you to be able to join him and that just can't happen unless he achieves his re-usability goals.

However, in terms of SpaceX current business you are basically right.  M1d on F9v1.1 and FH seem to service most/all of the current launch market, and (claims to) does it at (advertised) world beating prices. 

If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

Offline dwightlooi

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Re: SpaceX: Merlin 1D Updates thread
« Reply #409 on: 06/29/2012 02:02 am »
 
If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

There are two ways to look at this...

(1) If that engine costs say $500 million to develop and probably a little more to produce, it may make more sense to simply use the money to give the customers of the next 50 launches a $10 million discount. That's 4~6 years worth and will firmly establish the company as the player to beat in the industry.

(2) Another way to look at it however is that SpaceX has hired the minds and made the capital investments to design, develop and qualify rocket engines. Unless they want to immediately layoff their hard won talent pool, they will have to keep them on the payroll. This becomes a fix cost whether they use them to develop a new rocket engine or not. A large part of the development cost of a new engine hence will become an overhead they will have to pay whether they do anything with it or not.

But, if it's me, Super Draco and the launch escape application has way higher priority than upgrading the main propulsion engine(s) for the Falcon family. Beyond that, Super Draco can and should be developed into a long endurance engine. Long endurance meaning that it can be fired for 1~2 hours continuously. If you want to go to mars and come back, you need something that can sit in space for up to a year, then fire for that 0.9 km/s mars capture burn, possibly another 1.4km/s for MCO-LMO transition and another 1.4 km/s for earth return. A mission like that will probably need to burn tens of tons of propellant and it'll have to be truly storable propellant (nothing using LOX). You don't need a big engine -- big engines are heavy and need heavy thrust structures. You are just as well served with a tiny engine with a decent Isp burning for a long time. You can burn an RCS class thruster for days, but as the burn time gets ridiculous the thermal problems become questionable for ablatives. However, a Super Draco class thruster burning for 2~3 hours during an insertion burn is not unreasonable.

Offline Idiomatic

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Re: SpaceX: Merlin 1D Updates thread
« Reply #410 on: 06/29/2012 05:15 am »
 
If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

There are two ways to look at this...

(1) If that engine costs say $500 million to develop and probably a little more to produce, it may make more sense to simply use the money to give the customers of the next 50 launches a $10 million discount. That's 4~6 years worth and will firmly establish the company as the player to beat in the industry.

(2) Another way to look at it however is that SpaceX has hired the minds and made the capital investments to design, develop and qualify rocket engines. Unless they want to immediately layoff their hard won talent pool, they will have to keep them on the payroll. This becomes a fix cost whether they use them to develop a new rocket engine or not. A large part of the development cost of a new engine hence will become an overhead they will have to pay whether they do anything with it or not.

But, if it's me, Super Draco and the launch escape application has way higher priority than upgrading the main propulsion engine(s) for the Falcon family. Beyond that, Super Draco can and should be developed into a long endurance engine. Long endurance meaning that it can be fired for 1~2 hours continuously. If you want to go to mars and come back, you need something that can sit in space for up to a year, then fire for that 0.9 km/s mars capture burn, possibly another 1.4km/s for MCO-LMO transition and another 1.4 km/s for earth return. A mission like that will probably need to burn tens of tons of propellant and it'll have to be truly storable propellant (nothing using LOX). You don't need a big engine -- big engines are heavy and need heavy thrust structures. You are just as well served with a tiny engine with a decent Isp burning for a long time. You can burn an RCS class thruster for days, but as the burn time gets ridiculous the thermal problems become questionable for ablatives. However, a Super Draco class thruster burning for 2~3 hours during an insertion burn is not unreasonable.

IF FH meets price and payload targets and doesn't explode. They will be far cheaper than any of their competition. Why discount? I mean, unless they have extra rockets just laying around. Either way, they will be launching at the same rate: as fast as they can build them. The flexibility between F9 and FH means that they can easily move to fit the market.

Better to spend all that $ on his reusability ambitions. Build another grasshopper if it makes it work faster. Design a more deeply throttled engine. As well, his Mars ambitions. ISRU, landers, w/e the heck other mass of technology needed for mars. This keeps his talent pool.

Superdraco fired for 2 hours is 164,000kg of hypergols unless my math was terribly wrong. Even if there were a rocket that could put such a large spaceship into orbit.... The US would never allow it. Shit is dangerous. A leak would be like a small nuclear bomb going off.

Offline dwightlooi

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Re: SpaceX: Merlin 1D Updates thread
« Reply #411 on: 06/29/2012 06:14 am »
Superdraco fired for 2 hours is 164,000kg of hypergols unless my math was terribly wrong. Even if there were a rocket that could put such a large spaceship into orbit.... The US would never allow it. crap is dangerous. A leak would be like a small nuclear bomb going off.

Actually that's about right if you want a 2 man mission to mass. You'll need about 30 tons in LMO -- that includes a 20 tons for the earth return stack, the rest you leave behind. It takes about 144 tons of MMH/N2O4 to put about 75 tons on TMI from LEO. 75 tons is necessary if you want to put about 30 tons into LMO because you need to lose about 2.3km/s to get from TMI to LMO. So you'll be burning about 140~150 tons of hypergolics in nearly 2-hour burn if you use a Draco class engine.

As for putting that in orbit, it is not any more or less acceptable than launching a Titan with its 163 ton core booster loaded with 155 tons of Hypergolics. The difference is that you won't actually light it until it's in LEO where there are no collaterals to hurt if you blow up.

Offline Idiomatic

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Re: SpaceX: Merlin 1D Updates thread
« Reply #412 on: 06/29/2012 07:21 am »
Superdraco fired for 2 hours is 164,000kg of hypergols unless my math was terribly wrong. Even if there were a rocket that could put such a large spaceship into orbit.... The US would never allow it. crap is dangerous. A leak would be like a small nuclear bomb going off.

Actually that's about right if you want a 2 man mission to mass. You'll need about 30 tons in LMO -- that includes a 20 tons for the earth return stack, the rest you leave behind. It takes about 144 tons of MMH/N2O4 to put about 75 tons on TMI from LEO. 75 tons is necessary if you want to put about 30 tons into LMO because you need to lose about 2.3km/s to get from TMI to LMO. So you'll be burning about 140~150 tons of hypergolics in nearly 2-hour burn if you use a Draco class engine.

As for putting that in orbit, it is not any more or less acceptable than launching a Titan with its 163 ton core booster loaded with 155 tons of Hypergolics. The difference is that you won't actually light it until it's in LEO where there are no collaterals to hurt if you blow up.

I think if they are doing a mars shot it will be all new rockets and engines with not very much overlap from what we have now.

Offline oldAtlas_Eguy

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Re: SpaceX: Merlin 1D Updates thread
« Reply #413 on: 06/29/2012 08:42 pm »
Please keep it on the M1D. There are other threads for speculations on Dracos usage.

Offline CapitalistOppressor

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Re: SpaceX: Merlin 1D Updates thread
« Reply #414 on: 06/29/2012 11:15 pm »
(2) Another way to look at it however is that SpaceX has hired the minds and made the capital investments to design, develop and qualify rocket engines. Unless they want to immediately layoff their hard won talent pool, they will have to keep them on the payroll. This becomes a fix cost whether they use them to develop a new rocket engine or not. A large part of the development cost of a new engine hence will become an overhead they will have to pay whether they do anything with it or not.

^^  This is a critical point that still manages to understate its case. 

It's not just that they have an amazing development team that either gets used, gets wasted (and attrited away) or gets laid off.  It's that I don't think Elon Musk will ever stop investing in propulsion innovation.  Elon Musk is not just some corporate suit who looks at the bottom line and starts carving away with his pen knife.

The man styles himself as CTO, Chief Designer, etc.  He absolutely fancies himself as an engineer/designer and the last thing he wants to do is get rid of the engineering team that actually allows him to innovate. 

Personally, I think it would take the impending failure of his company to shut down his development team.  Once he finishes M1d (shameless plug for thread legitimacy) he will shift his team to something new, and process will continue for as long as he controls the company.

Offline Comga

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Re: SpaceX: Merlin 1D Updates thread
« Reply #415 on: 06/29/2012 11:26 pm »
T/W of 150 with vac thrust of 161klbf makes the upper weight number of 488kg, 160 T/W would be 457kg, so the bounds on the weight seem to be
457kg < engine weight < 488kg.

Stating that the T/W is more than 150 but not saying more than 160 means that it is somewhere between those two,....

That's MY kind of tea leaf reading.  Quite believable.

And you other guys, please take you staged combustion, hydrolox and other questions elsewhere.  This thread is for M1D Updates.  It's not "living dangerously" to go OT. It's living discourteously.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline modemeagle

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Re: SpaceX: Merlin 1D Updates thread
« Reply #416 on: 06/30/2012 12:58 am »
Not an update on the engine, but starting my next CAD project.

Offline cordor

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Re: SpaceX: Merlin 1D Updates thread
« Reply #417 on: 06/30/2012 08:44 pm »

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Before we even talk about the performance benefits of a Staged Combustion cycle and if it decreases reliability and safety margins, I think we should why we want to totally change the design of the Merlin in exchange for about 20 Isp. In short, why do we want more performance?

The F9 already has payload capacity of the EELVs. The FH already beats them by a factor of 2. That 20 Isp may get you another 2 tons of lift in an F9 and up to 5 on the FH. Really, does have 15 tons instead of 13 and/or 58 instead of 53 help SpaceX expand their launch manifest in any tangible way? If not, why isn't a simpler, safer, cheaper to build engine preferable to one with higher performance?


This post is OT, as pointed out by Martin, but as long as we are living dangerously . . .



a persuasive case that the proposed SC engine will burn CH3.

http://forum.nasaspaceflight.com/index.php?topic=26995.0


Third, SPX launchers would all get a big performance increase GTO and BEO with a high isp vac stage.  What you think SPX needs is not what Elon thinks it needs.  Elon badly wants to retire on Mars.  He is not doing that with a M1d vac upper stage.


Fifth, a lot of thread guesstimates point to the re-usability advantages of a CH4 SC engine in the context of Grasshopper.  Recent Russian test data support this line of thinking.  Elon <3's re-usability, because once he retires on Mars he wants you to be able to join him and that just can't happen unless he achieves his re-usability goals.

However, in terms of SpaceX current business you are basically right.  M1d on F9v1.1 and FH seem to service most/all of the current launch market, and (claims to) does it at (advertised) world beating prices. 

If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

1. Mars is an ultimate goal, but it's not part of spacex business, not yet. Right now, spacex needs positive cash flow, after that they need to bring the cost down, which is F9R for. Expensive high performance engine doesn't fit in at all.

2. Even if they are going to Mars, today. They are not going to do apollo style rocket and spacecraft. YOU CAN'T PACK 5 billionaires in a confined space for 6 months PERIOD that's no way to do businese. More likely, they will use FH to carry 30~40 ppl to LEO, from there, they will dock and aboard Interplanetary Spacecraft with private compartments, another FH will carry supplies onboard. And then the Interplanetary Spacecraft fire up it's ion thruster all the way to Mars.
« Last Edit: 06/30/2012 08:47 pm by cordor »

Offline arnezami

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Re: SpaceX: Merlin 1D Updates thread
« Reply #418 on: 06/30/2012 09:44 pm »
Not an update on the engine, but starting my next CAD project.
Great!

Keep in mind though that according to the very latest photo's the turbopump has significantly changed.

Offline modemeagle

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Re: SpaceX: Merlin 1D Updates thread
« Reply #419 on: 07/01/2012 12:00 am »
Not an update on the engine, but starting my next CAD project.
Great!

Keep in mind though that according to the very latest photo's the turbopump has significantly changed.
My drawing reflects the engine as of their open house at McGregor.  As soon as we have better photos I will get the turbo pump fixed.  At least I didn't waste time on the thrust structure, which has changed as well.

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