Author Topic: SpaceX: General Falcon and Dragon discussion (Thread 3)  (Read 568060 times)

Offline Ben the Space Brit

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #60 on: 02/23/2011 06:31 pm »
So, if they replace 9 Merlin 1's with 1 Merlin 2 it wouldn't be called a Falcon 9 anymore correct?
As 'Falcon-1' is already taken, I imagine that they would have to carry on calling it Falcon-9.  They'll probably give it a variant designation like 'Falcon-9a' or something.
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Offline Robotbeat

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #61 on: 02/23/2011 06:39 pm »
So, if they replace 9 Merlin 1's with 1 Merlin 2 it wouldn't be called a Falcon 9 anymore correct?
As 'Falcon-1' is already taken, I imagine that they would have to carry on calling it Falcon-9.  They'll probably give it a variant designation like 'Falcon-9a' or something.
I really doubt this will happen anytime soon. Remember how long it took since F-1 started development (1955) until first launch of the Saturn V (1967). And there's really nothing to say it'd be cheaper than 9 Merlin 1 engines.

I just simply don't see SpaceX developing the Merlin 2 without a big commitment from the government, such as a HLV contract.

Merlin 2 is NOT something to take for granted. SpaceX very publicly committed to Falcon 9 Heavy, but not to Merlin 2.

EDIT:And even for SpaceX, the Merlin engine took 6 years from development to first successful flight. A bigger engine wouldn't be easier, especially since they seem to be looking to do the turbopump themselves.
« Last Edit: 02/23/2011 06:44 pm by Robotbeat »
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Offline baldusi

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #62 on: 02/23/2011 07:27 pm »
How scalable are turbopump designs? I think very easy downscale (Rd-171 -> RD-180 -> RD-191), but very difficult upscale.
Please remember that one of the things that they changed from Merlin 1A(or B) to C was that they made their own turbopump. And the went from ablatively cooled to regeneratively cooled chamber. All made by themselves. Unless they want to improve ISP, they might do a "straight" upscale of the Merlin 1C (or D). And when I say "straight" I mean that they reinforce the ECU, use a pintle injector, regenerative cooled chamber, single shaft turbopump, etc.
« Last Edit: 02/23/2011 07:30 pm by baldusi »

Offline Jim

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #63 on: 02/23/2011 07:35 pm »

Please remember that one of the things that they changed from Merlin 1A(or B) to C was that they made their own turbopump.

They have yet to do that

Offline hop

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #64 on: 02/23/2011 07:43 pm »
How scalable are turbopump designs? I think very easy downscale (Rd-171 -> RD-180 -> RD-191), but very difficult upscale.
Hmm, my impression was always that turbo-machinery likes to be big, but I wouldn't swear by that.

AFAIK the (relative) ease of developing the RD-180 was due to the difficult problems of the engine development (oxygen rich, high pressure etc..) being already solved, and the ability to re-use the combustion chamber / nozzle designs with very little change.

Offline MP99

Elon already mentioned that they were looking at a cross-fed solution for multiple cores.  I believe that was in the interview just after the second F9 launch.

Assuming he means this for Falcon 9 Heavy, then there's no need to throttle down or leave out engines.

Also keep in mind that Falcon 9 Heavy will probably be migrating from 27 Merlin 1s to 3 Merlin 2s. 

Going by http://web02.aviationweek.com/aw/mstory.do?id=news/awst/2010/11/29/AW_11_29_2010_p28-271784.xml&channel=space&headline=NASA%20Studies%20Scaled-Up%20Falcon,%20Merlin, and discussion at http://forum.nasaspaceflight.com/index.php?topic=23464.0...

It appears that the standard 125mT Falcon X is achieved with all three cores staging together (no cross-feed). That's 3.3x the single-stick figure.

Cross-feed seems to take it up to 4x (150mT) - about a 20% performance boost.

Suggests it would provide a neat boost to performance of F9H, although not sure what payload might need that. The simplicity of single-staging seems to be an advantage in itself.

cheers, Martin

Offline baldusi

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #66 on: 02/23/2011 08:29 pm »

Please remember that one of the things that they changed from Merlin 1A(or B) to C was that they made their own turbopump.

They have yet to do that
My bad, memory sometimes plays tricks on me.

Offline tigerade

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #67 on: 02/23/2011 10:47 pm »
SpaceX one of 50 most innovative companies in MIT's Technology Review:

http://www.technologyreview.com/tr50/

Offline mr. mark

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #68 on: 02/24/2011 05:09 am »
This is all very nice and all but, all I want to see is Spacex having a nice new update with lots of good pics and the news we have been waiting for which is a combined COTS 2/3 mission for this summer. Elon can get the best buttocks of the year award for all I care. Spacex needs to get down to business and update us as soon as they can about they're progress. By the way what's up with their website? They really need better website management. Their pictures page has not been updated since 2009. Compare that to Orbital's website which seems to be updated regularly. If you are trying to persuade a sceptical public, a nice first step is to reach the public through the web.

Offline Patchouli

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #69 on: 02/24/2011 05:43 am »
How scalable are turbopump designs? I think very easy downscale (Rd-171 -> RD-180 -> RD-191), but very difficult upscale.
Hmm, my impression was always that turbo-machinery likes to be big, but I wouldn't swear by that.

AFAIK the (relative) ease of developing the RD-180 was due to the difficult problems of the engine development (oxygen rich, high pressure etc..) being already solved, and the ability to re-use the combustion chamber / nozzle designs with very little change.

From what I read turbines do indeed perfer to be big as when you down scale them you end up fighting with issues such as sealing and keeping parts that do not like high temps cool.

It certiantly is not easier to make them big but they are gernerally more efficient the larger they are.

Really this rule seems to apply to rockets in general.
« Last Edit: 02/24/2011 05:47 am by Patchouli »

Online Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #70 on: 02/24/2011 12:44 pm »

Cross-feed seems to take it up to ... about a 20% performance boost.

Suggests it would provide a neat boost to performance of F9H, although not sure what payload might need that.

The latest SpaceX presentation shows F9H with elongated tanks (see picture).  This implies either:
a) cross-feed
b) throttling down the main core, either by adjusting the pintle, or by removing engines

My point was that Elon had mentioned the cross-fed solution in a previous interview. 

Here's a question: If you add up all possible F9H performance boosts:
1) cross-feed
2) elongated boosters
3) Raptor second stage
4) Replace 27 Merlin1s with 3 Merlin2s
what would you guess for payload capacity?


Offline kevin-rf

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #71 on: 02/24/2011 12:45 pm »
By the way what's up with their website? They really need better website management.

And websites are the core business? I would rather they do what they say they are going to do in the time frame they claim they will than have a pretty website.
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Online Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #72 on: 02/24/2011 01:16 pm »
I just simply don't see SpaceX developing the Merlin 2 without a big commitment from the government, such as a HLV contract.

I think SpaceX will do Merlin-2 regardless.  9 small engines is a great way to get a startup going, but it's not a great long term solution. It'll just take SpaceX a lot longer to do Merlin 2 on their own.   

As for an HLV contract, remember that Falcon-X carries roughly the same payload as Falcon 9 Heavy, and SpaceX definitely believes there's a commercial market for a launcher this size. 

In fact, SpaceX president Gwynne Shotwell talked about this specifically back in April.  Combining 2 large commercial GTO satellites (~7 mT each) on that type of launcher would dramatically reduce the cost per pound. 
http://www.thespaceshow.com/detail.asp?q=1348
(starting around 33:15 into the program).

And don't forget that Merlin 2 can be used on Falcon 9 to reduce cost and increase payload capacity, again helping SpaceX commercially.

So while Falcon X Heavy would be for NASA, Falcon X and Merlin 2 have commercial applications.  With this in mind, perhaps the HLV could be developed using a public/private partnership instead of a traditional contract.  This way, NASA wouldn't have to foot the entire bill for HLV development.
« Last Edit: 02/24/2011 01:20 pm by Dave G »

Offline mnagy

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #73 on: 02/24/2011 01:23 pm »
And don't forget that Merlin 2 can be used on Falcon 9 to reduce cost and increase payload capacity, again helping SpaceX commercially.
Are you sure about that? IIRC, Merlin 2 would cost $50M, which is the price of one Falcon 9. For F9H, this seems even worse..

Online Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #74 on: 02/24/2011 01:46 pm »
And don't forget that Merlin 2 can be used on Falcon 9 to reduce cost and increase payload capacity, again helping SpaceX commercially.
Are you sure about that? IIRC, Merlin 2 would cost $50M, which is the price of one Falcon 9. For F9H, this seems even worse..

Some presentations have loose numbers, but it's not clear if these refer to the engine or the whole launcher.

In my mind, it's obvious that one engine will have less recurring cost than 9 smaller ones.  Remember that the key here is to use Merlin 2 on Falcon 9 for regular commercial satellites, so the launch rate would be fairly good.  If you just used Merlin 2 on NASA HLVs, then recurring costs would be higher.




Online Nate_Trost

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #75 on: 02/24/2011 01:57 pm »
In my mind, it's obvious that one engine will have less recurring cost than 9 smaller ones.

You're discounting the development cost, which even a SpaceX presentation put at a billion dollars. Even assuming it's somehow only half that, that's still $500 million. SpaceX is not going to have that kind of money to spend on Merlin 2. Unless you're suggesting SpaceX will take the long approach and shoot to have it ready by like 2025.

Online Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #76 on: 02/24/2011 02:34 pm »
SpaceX is not going to have that kind of money to spend on Merlin 2. Unless you're suggesting SpaceX will take the long approach and shoot to have it ready by like 2025.

If SpaceX has to develop Merlin 2 on their own, it may take 5-15 years, depending on how much money they get from the IPO and other commercial business. So 2025 is not out of the question.

If NASA uses a public/private partnership with SpaceX to develop the HLV, then Merlin 2 will obviously happen much sooner.

Either way, I believe SpaceX will develop Merlin 2.
« Last Edit: 02/24/2011 02:38 pm by Dave G »

Offline tegla

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #77 on: 02/24/2011 02:44 pm »
OK, how big part of Merlin 2 price quote is the result of "NASA would want SpaceX to do it in a hurry"?

Or from an other viewpoint, how much would developing M2 cost for SpaceX, if it is on a "slow but steady" development path?

Online Nate_Trost

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #78 on: 02/24/2011 02:54 pm »
SpaceX is not going to have that kind of money to spend on Merlin 2. Unless you're suggesting SpaceX will take the long approach and shoot to have it ready by like 2025.

If SpaceX has to develop Merlin 2 on their own, it may take 5-15 years, depending on how much money they get from the IPO and other commercial business. So 2025 is not out of the question.

If NASA uses a public/private partnership with SpaceX to develop the HLV, then Merlin 2 will obviously happen much sooner.

Either way, SpaceX will develop Merlin 2.

IPO is not a given and would primarily be to serve investors and employees with stock options. It isn't going to raise a lot of money. Even if SpaceX manages to maintain a 10-15% profit margin, that still a limited amount of profit to channel into R&D.

So, I'd suggest that it's very unlikely Merlin 2 will be developed, unless somebody is willing to write a very large check and is unconcerned with ROI. I'm not sure I'd hold my breath waiting for that.

Online Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #79 on: 02/24/2011 03:06 pm »
OK, how big part of Merlin 2 price quote is the result of "NASA would want SpaceX to do it in a hurry"?

Or from an other viewpoint, how much would developing M2 cost for SpaceX, if it is on a "slow but steady" development path?

Or looking at it the other way: SpaceX has a team of rocket engine developers, and Merlin 1 is basically done.  In order to retain that talent, they'll need to have something to develop.
« Last Edit: 02/24/2011 03:07 pm by Dave G »

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