Author Topic: Falcon 9 additional performance (12 tons)  (Read 70762 times)

Offline edkyle99

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Re: Falcon 9 additional performance (12 tons)
« Reply #40 on: 02/18/2009 06:04 pm »

I wouldn't be surprised if they started messing around with LOX/LH2 just to get familiar with it.  Do something like a small Kestrel-sized LOX/LH2 engine for starters, just to try and learn all the subtleties that you can never pick up just from textbooks.  And then if that works out, work their way up to bigger Merlin-sized LOX/LH2 upper stage engines.

~Jon

I would like to see this team keep doing what it knows best, which appears to be pintle injector kerosene engine development.  After vacuum Merlin, it would seem to me a good idea to look at higher-thrust booster kerosene engines.  Would it, for example, be cost effective to replace the nine Merlin 1C engines on the Falcon 9 first stage with four engines, or three, or two, or one.     

 - Ed Kyle

Offline R.Simko

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Re: Falcon 9 additional performance (12 tons)
« Reply #41 on: 02/18/2009 06:34 pm »
Would expanding the first stage and creating a Falcon 12 or even a Falcon 16 be practicle?

Offline jongoff

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Re: Falcon 9 additional performance (12 tons)
« Reply #42 on: 02/18/2009 07:19 pm »
Would expanding the first stage and creating a Falcon 12 or even a Falcon 16 be practicle?

Possible, yes.  Practical? Probably not.  That's a lot of engines.  Nine engines is already pushing things a bit.  There's a reason why we backed down from twelve engines to five for our current suborbital plans.  You need at least four to get decent engine-out capabilities, but much past that and you start getting more complexity than it is worth.

~Jon

Offline jongoff

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Re: Falcon 9 additional performance (12 tons)
« Reply #43 on: 02/18/2009 07:22 pm »
I would like to see this team keep doing what it knows best, which appears to be pintle injector kerosene engine development.  After vacuum Merlin, it would seem to me a good idea to look at higher-thrust booster kerosene engines.  Would it, for example, be cost effective to replace the nine Merlin 1C engines on the Falcon 9 first stage with four engines, or three, or two, or one.

Well, I agree that making a scaled up Merlin that would allow them to keep the engine count down to like 5 or so would be a big win.  I actually like engine-out capability.  That said, there would be good benefits from them having the capability to do high-thrust cryo upper stage engines.  Right now there's only one supplier of such engines in the US (P&WR), and having some competition there would be good.  Plus, as Gary Hudson once put it to me, if the RL-10 had actually been an RL-100 instead (ie 100klbf expander cycle engine), the history of the space age might have ended up very differently.

~Jon

Offline Lars_J

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Re: Falcon 9 additional performance (12 tons)
« Reply #44 on: 02/18/2009 07:43 pm »
Well, I agree that making a scaled up Merlin that would allow them to keep the engine count down to like 5 or so would be a big win. 

I doubt that they would create another engine that had less than 2x the thrust of their current one.

No I predict that any 'big Merlin' would have at least 5x-10x thrust.

Offline rklaehn

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Re: Falcon 9 additional performance (12 tons)
« Reply #45 on: 02/18/2009 08:36 pm »
Well, I agree that making a scaled up Merlin that would allow them to keep the engine count down to like 5 or so would be a big win. 

I doubt that they would create another engine that had less than 2x the thrust of their current one.

No I predict that any 'big Merlin' would have at least 5x-10x thrust.

I really don't see the point of building a big merlin. If the 9 engine configuration can not be made to work reliably, spacex will not design any new engines. And if it can be made to work, why should they change?

It might not be as sexy as designing a F1 class engine or a hydrogen upper stage engine, but I think that if they can get the 9 engine configuration to work, they should incrementally improve the merlin engine:

-reduce the probability of explosive failure
-test the containment of the kevlar shields by blowing up engines on the test stand in various ways
-improve reusability
-improve salt water compatibility
-simplify manufacturing
-reducing part count
-increase performance

That should keep the engine design team busy for a few years. And if they finish all that they could build a stage combustion engine with the same thrust as merlin.

Offline ugordan

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Re: Falcon 9 additional performance (12 tons)
« Reply #46 on: 02/18/2009 08:51 pm »
It might not be as sexy as designing a F1 class engine or a hydrogen upper stage engine, but I think that if they can get the 9 engine configuration to work, they should incrementally improve the merlin engine:

Merlin already went through several improvement iterations and is expected to be uprated again by over 20% in thrust. That's about at the margins it's thought to be able to handle. There's only so much you can squeeze out of a given engine.

For vanilla F9, there's not much point in pursuing a bigger engine, but F9 performance (especially GTO performance) is at mid to lower end of EELVs. If they choose not to pursue a high energy upper stage, it leaves a F9 Heavy-like configuration for heavier lift. While 9 engines is manageable, 27 engines is a chore.

I could envision a bigger engine, Merlin 2 being used as an interim solution on both a F9H variant as well as a clustered unit for a much bigger, future LV, but that'd be still some years into the future. They'd probably want to make it throttleable which, with a pintle injector, ought not be excruciatingly difficult.

As jongoff said, there aren't really many payloads that would justify even F9H, unless you used it for GTO missions like an Ariane 5. That said, it wouldn't really surprise me if Elon went ahead with developing it even if no customer was booked at first.

The question is, if you wanted to increase performance, especially on high delta-V missions, would it be cheaper to develop a LH2 engine or just scale up an all-kerolox booster? It seems to me introducing LH2 into the equation would give SpaceX more trouble than it's worth.
« Last Edit: 02/18/2009 08:53 pm by ugordan »

Offline rklaehn

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Re: Falcon 9 additional performance (12 tons)
« Reply #47 on: 02/18/2009 09:01 pm »
It might not be as sexy as designing a F1 class engine or a hydrogen upper stage engine, but I think that if they can get the 9 engine configuration to work, they should incrementally improve the merlin engine:

Merlin already went through several improvement iterations and is expected to be uprated again by over 20% in thrust. That's about at the margins it's thought to be able to handle. There's only so much you can squeeze out of a given engine.

I was thinking mostly about non performance-related improvements. For example, if they could show that their containment system really works under most conditions, that would go a long way to show that they really have engine-out capability.

And since a merlin has never been fired after being immersed in salt water, I am sure there are a lot of improvements in that area as well.

Offline ugordan

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Re: Falcon 9 additional performance (12 tons)
« Reply #48 on: 02/18/2009 09:10 pm »
I was thinking mostly about non performance-related improvements. For example, if they could show that their containment system really works under most conditions, that would go a long way to show that they really have engine-out capability.

And since a merlin has never been fired after being immersed in salt water, I am sure there are a lot of improvements in that area as well.

My personal belief is this liquid-engine-blowing-up thinking is exaggerated. It's rarely going to be the way an engine goes out (which should also be a rare occurence), most likely a benign shutdown will happen given health monitoring and all. Even if it didn't, there's an old SpaceX update saying all "blow-up" events and fragments they saw during testing couldn't penetrate even 2 mm of aluminum.

As for salt water immersion, I can definitely agree that's a potential improvement program.

Offline nooneofconsequence

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Re: Falcon 9 additional performance (12 tons)
« Reply #49 on: 02/18/2009 09:15 pm »
I really don't see the point of building a big merlin. If the 9 engine configuration can not be made to work reliably, spacex will not design any new engines. And if it can be made to work, why should they change?

The point is evolving the business. The whole point of using bunches of merlin's was to extensively reuse the merlin design history, in this case to get into a Delta class launch vehicle market with a reliable product.

The next challenge after making it into this market will be becoming a reliable launch service provider. They don't appear to be courting many Pegasus/Tarus accounts that they could compete for, so likely is that Falcon 1 is not the core of the market, or even lower half. More likely is that Delta class is the bottom, and larger to beyond EELV (perhaps Ariane V?) is where they want to be. By proving 9 engines per stage as a reliable vehicle, they can address a larger scale launch vehicle with the approaches learned, but only with a larger engine, and at some point there's only so far you can push the merlin 1.

To reduce costs/increase reliability they'll do another, bigger Kerolox. Staged combustion is nothing like pintel injector designs, and runs counter to the whole methodology that works for them. All they need is a bigger Merlin.

Following their methodology, a single engine powered version of the Falcon 9 makes most sense, that they gang for a larger lv, and use with a nozzle extension/vacuum version for its stage 2.

Don't see any signs of a cryo high energy second stage, which is the weak spot in all of the competition these days. Its too risky/complex/costly for all concerned. Even ESA put off the ECB as long as it could.

Cross feeds aren't necessary for this business - fielding a reliable product (eg. fewer working parts) and covering the desired range of capabilities (top end of EELV range) are.
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

Offline rklaehn

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Re: Falcon 9 additional performance (12 tons)
« Reply #50 on: 02/18/2009 09:22 pm »
The question is, if you wanted to increase performance, especially on high delta-V missions, would it be cheaper to develop a LH2 engine or just scale up an all-kerolox booster? It seems to me introducing LH2 into the equation would give SpaceX more trouble than it's worth.

If you just want to increase performance to LEO, then LH2 is probably not worth it. I am not even sure if it is worth it for GTO. But as soon as you want to go to escape trajectories, LH2 really starts to be superior. Since elon wants to go to mars, he will want a LH2 stage as soon as possible.

It is a shame that lockheed probably does not want to do business with spacex. A falcon topped off with a wide body centaur would be a fantastic vehicle with 100% american engines. And duplicating the technology lockheed has with the centaur would take spacex a long time.

Offline rklaehn

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Re: Falcon 9 additional performance (12 tons)
« Reply #51 on: 02/18/2009 09:27 pm »
To reduce costs/increase reliability they'll do another, bigger Kerolox. Staged combustion is nothing like pintel injector designs, and runs counter to the whole methodology that works for them. All they need is a bigger Merlin.

Why should going to one engine increase reliability? You think the engine out capability won't work because engines will explode so violently that they take out their neighbors despite the kevlar shields?

When was the last time a liquid engine failed explosively on an operational launcher? (This is not a rhetorical question. I am genuinely interested :-)
« Last Edit: 02/18/2009 09:41 pm by rklaehn »

Offline nooneofconsequence

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Re: Falcon 9 additional performance (12 tons)
« Reply #52 on: 02/18/2009 09:41 pm »
To reduce costs/increase reliability they'll do another, bigger Kerolox. Staged combustion is nothing like pintel injector designs, and runs counter to the whole methodology that works for them. All they need is a bigger Merlin.

1.Why should going to one engine increase reliability? You think the engine out capability won't work because engines will explode so violently that they take out their neighbors despite the kevlar shields?

2.When was the last time a liquid engine failed explosively? (This is not a rhetorical question. I am genuinely interested :-)
1.You can add parts (more engines, more for crossfeeds, more for ...) or you can remove parts (remove engines). More parts, more potential for failure. Less parts, less chances for failure. QC/QA works much better.

You don't depend on containing failure for eliminating failure. Containing failure just reduces the chances that the failure results in LOC/LOM. They are not the same.

2. On the test stand, many times in recent history. In flight - that's a whole different category. Too many LV failures and no company. Look how quickly payloads for each of the Falcon 1 prior flight peeled away. No one wants to risk a payload on a failure prone launch vehicle.
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

Offline edkyle99

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Re: Falcon 9 additional performance (12 tons)
« Reply #53 on: 02/18/2009 09:44 pm »

If you just want to increase performance to LEO, then LH2 is probably not worth it. I am not even sure if it is worth it for GTO. But as soon as you want to go to escape trajectories, LH2 really starts to be superior. Since elon wants to go to mars, he will want a LH2 stage as soon as possible.

It is a shame that lockheed probably does not want to do business with spacex. A falcon topped off with a wide body centaur would be a fantastic vehicle with 100% american engines. And duplicating the technology lockheed has with the centaur would take spacex a long time.

The HYLAS launch would be, if I'm reading my history correctly, the first-ever two-stage all-kerosene launch to GTO.  That seems to me something that could be used to competitive advantage in this business.

When Mr. Musk first announced Falcon 5, he talked about a possible future upgrade that would have included an RL10 powered second stage.  Perhaps he would still consider a non-SpaceX engine for this application, but I doubt he would want to use an entire stage, even if it were plausible.  Centaur was designed to fly Atlas.  It would be a big effort to adapt it for use on another rocket, though it admittedly has, in various forms, flown atop several different launch vehicles over the years (several Rocketdyne Atlas booster types, the balloon tank Atlas III powered by RD-180, Atlas V, Titan IIIE, and Titan IV - and it almost flew in Shuttle's payload bay). 

 - Ed Kyle
« Last Edit: 02/18/2009 09:47 pm by edkyle99 »

Offline ugordan

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Re: Falcon 9 additional performance (12 tons)
« Reply #54 on: 02/18/2009 09:51 pm »
You can add parts (more engines, more for crossfeeds, more for ...) or you can remove parts (remove engines). More parts, more potential for failure. Less parts, less chances for failure. QC/QA works much better.

That's one way to spin it. The other way would be added redundancy and engine-out capability, limited as it is.

Consider what appears to be a common cause for engine loss - foreign object debris in the LOX tank. Ingest the particle into the turbopump and it's trashed. If it's the only one in your stage you just bought the farm. If that same particle was ingested into a smaller turbopump in one of several engines, it doesn't necessarily mean loss of mission.

As far as in-flight liquid failures go (let's be fair and not count test stand abuse and development tests), I inquired about that here already and it appears the last explosive failure was back in the prehistoric days of the space age or something like that.

Offline nooneofconsequence

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Re: Falcon 9 additional performance (12 tons)
« Reply #55 on: 02/18/2009 09:59 pm »
When Mr. Musk first announced Falcon 5, he talked about a possible future upgrade that would have included an RL10 powered second stage.
I read that more as he desired to have an cryo upperstage/transstage capability, and used Centaur as a way to describe it.

As if he wished to discover some start-up company with such, that he could acquire/partner with, and gain that capability.

Often times, from the environment that Musk comes from, speaking as he did inspires people who have such to beat a fast path to him.
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

Offline nooneofconsequence

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Re: Falcon 9 additional performance (12 tons)
« Reply #56 on: 02/18/2009 10:06 pm »
You can add parts (more engines, more for crossfeeds, more for ...) or you can remove parts (remove engines). More parts, more potential for failure. Less parts, less chances for failure. QC/QA works much better.

That's one way to spin it. The other way would be added redundancy and engine-out capability, limited as it is.

Consider what appears to be a common cause for engine loss - foreign object debris in the LOX tank. Ingest the particle into the turbopump and it's trashed. If it's the only one in your stage you just bought the farm. If that same particle was ingested into a smaller turbopump in one of several engines, it doesn't necessarily mean loss of mission.

As far as in-flight liquid failures go (let's be fair and not count test stand abuse and development tests), I inquired about that here already and it appears the last explosive failure was back in the prehistoric days of the space age or something like that.
Any anomaly lessens trust in a vehicle. You can't forstall the extent of damage to a vehicle. That you get lucky and make it to proper orbit isn't the shining success you want, since people will think it a fluke.

Last case of FOD and exploding liquid fueled boosters was just last year.

Don't talk about test stand abuse - the  only place for a engine failure IS THE TEST STAND! These things are weapons, plain and simple. Expecting that you can tolerate a small "boom!" in a skyscraper of high explosive not to go off is simply nuts!

Any parts you add to increase "reliability" can themselves become unreliable.
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

Offline Danderman

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Re: Falcon 9 additional performance (12 tons)
« Reply #57 on: 02/18/2009 10:25 pm »
When was the last time a liquid engine failed explosively on an operational launcher? (This is not a rhetorical question. I am genuinely interested :-)

Well, there was the SeaLaunch failure a couple of years ago, and there was the 1990 Zenit failure:


Offline ugordan

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Re: Falcon 9 additional performance (12 tons)
« Reply #58 on: 02/18/2009 10:28 pm »
Any anomaly lessens trust in a vehicle. You can't forstall the extent of damage to a vehicle. That you get lucky and make it to proper orbit isn't the shining success you want, since people will think it a fluke.

If you come in as a customer to the launch provider, ANY provider, and expect a perfect flight all the time, every time, then I have to say you shouldn't be into launching stuff in the first place. What do you think satellite insurance is for?

I couldn't disagree more with the above statements. Saying that a successful delivery of payload to the target orbit is NOT success is ludicrous. The whole point of reduncancy is to protect against an INEVITABLE event when one engine fails. Machines fail and statistically, sooner or later an engine fails. It's not a bad design if it's able to cope with a snag, it's a bad design if it isn't able.

I have to ask: what's so different in a rocket that engine redundancy is bad, while in a passenger jet it's a safety feature? Would you like to ride a big jet with one engine only and a seagull kills it, you crash, or would you rather have 2 or more engines? Would you call a safe landing in the 2nd case good plane design or would you call yourself living to see the next sunrise a fluke?

Last case of FOD and exploding liquid fueled boosters was just last year.

Care to name this failure?

Don't talk about test stand abuse - the  only place for a engine failure IS THE TEST STAND! These things are weapons, plain and simple. Expecting that you can tolerate a small "boom!" in a skyscraper of high explosive not to go off is simply nuts!

Any parts you add to increase "reliability" can themselves become unreliable.

I'm sorry, I don't follow your logic at all here. You do realize engine failures are not 100% preventable, do you? Do you also realized all the recent liquid engine failures in flight were non-explosive?

Offline ugordan

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Re: Falcon 9 additional performance (12 tons)
« Reply #59 on: 02/18/2009 10:31 pm »
Well, there was the SeaLaunch failure a couple of years ago, and there was the 1990 Zenit failure:

SeaLaunch lost thrust and collapsed onto itself resulting in a big fireball. I didn't see reports saying it was an explosive engine failure. The same scenario appears to happen in that Zenit video.

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