Author Topic: SpaceX advances drive for Mars rocket via Raptor power  (Read 545542 times)

Offline baldusi

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #40 on: 03/08/2014 12:52 am »
It's vacuum 1Mlbf. So it should be more like an RD-180 at SL. The propellant would be only 78% of what they currently get since it's less dense. So 20% lighter, slightly worse T/W, but 41s/52s of isp advantage. Main issue would be upper stage. Gas generator kerolox isn't that good for high energy performance. My wild guess, close performance but reusability is highly complicated and ground ops would need RP-1 and CH4.
I simply don't see it.

Offline clongton

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #41 on: 03/08/2014 02:02 am »
Awesome article Alejandro. Superb work.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Online Coastal Ron

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #42 on: 03/08/2014 02:23 am »
Has anybody run the numbers on a rocket using 1 of these as a first stage engine?

What would be the point of such vehicle? Inferior to F9 and almost certainly expendable.

What's the point of the 9 engined beast they say it is for?

I'm trying to figure out if this thing fits anywhere else.

Per the article:

"Known as the Raptor, nine of these immensely powerful engines – one or three cores – will be utilized to send SpaceX’s Super Heavy Lift Launch Vehicle (SHLV) uphill on missions to Mars.

Keep in mind though that Musk is building this for his own set of requirements.  What that will be, and who will be paying for the complete launcher and it's payloads are unknown at this point.  But Musk recently stated that for what he thinks needs to happen, there was a need for a resuable heavy lift system, hence the need for engines that can be used many times.

As to the comment from R7, I think they meant that a single Raptor engine would not be able to throttle down enough to be reusable in a one-engine-per-core configuration.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Elmar Moelzer

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #43 on: 03/08/2014 02:38 am »
Question: If SpaceX builds a this or any HLV, will NASA then be legally required to give up SLS and begin purchasing from SpaceX?
I think in theory NASA has a legal responsibility to use commercial LV's if they meet it's requirements (see Robotbeats sig)

But of course that leaves a lot of wiggle room for wheather a commercial LV "meets" their needs.

Just because it might meet all of NASA's needs does not necessarily mean it would meet the Legislatures needs.  :(  :(

The other issue is schedule.  Right now SLS is due for 1st flight in (IIRC) 2018. Spacex's offering is (presumably) much further out.  :( :(
From what I understand, the first version of the SLS wont have the full capability anyway and subsequent versions might use different components.

Online vt_hokie

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #44 on: 03/08/2014 03:50 am »
I can't wait to see how big the Alpha Centauri rocket ends up being!

Offline Damon Hill

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #45 on: 03/08/2014 04:13 am »
I can't wait to see how big the Alpha Centauri rocket ends up being!

Check out some of the Nova-class concepts of the 60s, with SpaceX's components.

Fascinating and informative article.

Offline sdsds

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #46 on: 03/08/2014 04:22 am »
Has anybody run the numbers on a rocket using 1 of these as a first stage engine?

I think the more interesting question is what a 3 engine first stage could provide. More than F9 and less than FH?

Per the article:
"Known as the Raptor, nine of these immensely powerful engines – one or three cores – will be utilized to send SpaceX’s Super Heavy Lift Launch Vehicle (SHLV) uphill on missions to Mars.
-- sdsds --

Offline Zed_Noir

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #47 on: 03/08/2014 05:07 am »
Has anybody run the numbers on a rocket using 1 of these as a first stage engine?

What would be the point of such vehicle? Inferior to F9 and almost certainly expendable.

What's the point of the 9 engined beast they say it is for?

I'm trying to figure out if this thing fits anywhere else.

I posted previously that you could swapped 2 Raptors for 9 Merlins in a LV with stock F9 tankage to test out the Raptors real quick for a limited number of flights. Would not be reusable or efficient. The point is the  hacked together LV will have the Raptor engine flying the soonest at minimal development cost.

Or you can use the F9 tooling to make properly proportion tankage for an expandable dual engine core LV with Raptors near the end of their life cycle. Which in theory will also be the possibility of a tri-core heavy version with cross-feeding with 6 Raptors.


Offline TomH

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #48 on: 03/08/2014 05:24 am »
We know they want to lease VAB space and Pad 39A, but a tri-core of 10m per core is too big for the doors, and the cost of building their own new assembly facilities for something that big would be immense. So unless I'm missing something, I just don't see how anyone is going to pull off a tri-core that's 30m wide. Obviously for reusability, the octagon + center engine configuration works well for RTLS.

I believe just under 7m per core is about the largest you could fit for a tri core through the VAB doors, so it would seem that they are thinking either 3 x 7m cores or a 10-13m single core. Can you say NOVA?
« Last Edit: 03/08/2014 05:27 am by TomH »

Offline Zed_Noir

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #49 on: 03/08/2014 05:42 am »
We know they want to lease VAB space and Pad 39A, but a tri-core of 10m per core is too big for the doors, and the cost of building their own new assembly facilities for something that big would be immense. So unless I'm missing something, I just don't see how anyone is going to pull off a tri-core that's 30m wide. Obviously for reusability, the octagon + center engine configuration works well for RTLS.

I believe just under 7m per core is about the largest you could fit for a tri core through the VAB doors, so it would seem that they are thinking either 3 x 7m cores or a 10-13m single core. Can you say NOVA?

IIRC SpaceX is only interested in the 39A pad. Guess SpaceX will throw up their own HIF near the pad. After all the only currently envisaged payload is the MCT which make the whole LV stack really lightweight..


Offline TrevorMonty

Great article.

Being following this on L2 nice to see it released to the public.

I was originally of option of a 50t-70t reusable LV to replace both FH and F9 but have come around to bigger better concept. Currently there is no market for 50t-70t LV so why target that market, it is to small for going to Mars.
If they are going to create a new engine and LV they may as well go for broke and make 100t plus single core. The LV in reuseable form may even get launch prices down to <$500kg eg $25M for 50t+.


Offline DJPledger

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #51 on: 03/08/2014 08:35 am »
As far as we know SpaceX are not planning a Raptor powered LV with less than 9 Raptors on the 1st stage. They have settled on 9 engine 1st stage designs for 1st stage RTLS and engine out capability. Single and 3 engined 1st stages won't have engine out capability and RTLS would be extremely difficult. Engine out capability and RTLS are both extremely important for SpaceX.

There is no point in discussing single, 3, and 5 Raptor 1st stages as there is virtually no chance that SpaceX will develop them. Raptor has been sized for 9 engine cores for SpaceX's Mars ambitions.

Offline woods170

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #52 on: 03/08/2014 08:58 am »
Are the legs scaled to the same ratio as the F9? The appear to barely be able to reach the ground from their mount points, much less be a stable base.

The images of the engine section and legs are notional. Do not read "the thruth" in them. They are just there to help people visualize what is being told in the article. Nothing more, nothing less.
« Last Edit: 03/08/2014 08:59 am by woods170 »

Offline R7

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #53 on: 03/08/2014 09:17 am »
What's the point of the 9 engined beast they say it is for?

I'm trying to figure out if this thing fits anywhere else.

That's the five-hundred-thousand-dollars question. The economics of BFR/MCT seem a bit of taboo.

Other usages ... comsats grow a lot larger? RD-180 substitute  ;D ?
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Offline baldusi

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #54 on: 03/08/2014 11:43 am »
I believe that making a reusable SHLV like the 9 Raptor core they plan would be risky. As such they'll have to copy as much as they can from the F9R experience. Whatever works and they understand they should keep.
From what I see SpaceX has shown good technology risk management. If they are aiming to the most advanced engine ever, and an unproven propellant, they'll surely try to constrain the risk in other systems.

Offline R7

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #55 on: 03/08/2014 11:44 am »
We know they want to lease VAB space and Pad 39A, but a tri-core of 10m per core is too big for the doors, and the cost of building their own new assembly facilities for something that big would be immense. So unless I'm missing something, I just don't see how anyone is going to pull off a tri-core that's 30m wide.

Move the rocket through the door sideways? Does LUT have to be transported with it, leave it at the pad?
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Online guckyfan

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #56 on: 03/08/2014 12:05 pm »
We know they want to lease VAB space

Do you have a source for that?


Offline CuddlyRocket

What's the point of the 9 engined beast they say [the Raptor] is for?

A single-core with nine Raptors is probably cheaper to build than an FH with its three cores and 27 Merlins and have greater performance with easier RTLS. Thus the FH can probably be replaced when this comes into service - but lessons will have been learned in the meantime!

Offline Avron

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #58 on: 03/08/2014 01:05 pm »
We know they want to lease VAB space

Do you have a source for that?



That should be interesting, do we know they want to assemble vertically  or just use it for core storage?

Offline Avron

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Re: SpaceX advances drive for Mars rocket via Raptor power
« Reply #59 on: 03/08/2014 01:08 pm »
What's the point of the 9 engined beast they say [the Raptor] is for?

A single-core with nine Raptors is probably cheaper to build than an FH with its three cores and 27 Merlins and have greater performance with easier RTLS. Thus the FH can probably be replaced when this comes into service - but lessons will have been learned in the meantime!

What I don't get is why just three cores, look at  Buran booster concept , why not a central core and 4 attached cores?

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