Possible SpaceX Vehicle Configurations based on recent (10/23) Raptor information

[Lars_J]

malu5531,

Ok, I see some of your assumptions (didn't scroll down before). I tried to see a plain F9v1.1 LEO payload calculations to see if your math adds up...

But I didn't see it. Just F9R - but that one seems to assume reuse of both stages, and *still* get a 13150 kg payload to LEO. I think you've got it wrong here... The 13150 kg is certainly without 2nd stage reuse. And it may not even be plausible with just first stage reuse. (Given Elon's statement of a 15% payload hit with boost-forward recovery, and 30% hit with boost-back recovery)

This is an example of the over-optimistic assumption that I fear is spread through your spreadsheets - which are otherwise very well done.

[gin455res]

and how wuud a single raptor core, with a merlin vacuum upper stage fair (for smaller payloadz)?

[malu5531]

But I didn't see it. Just F9R - but that one seems to assume reuse of both stages, and *still* get a 13150 kg payload to LEO. I think you've got it wrong here... The 13150 kg is certainly without 2nd stage reuse.

I should make that clear in the spreadsheet; 13150 kg is without second stage reuse. I only have a comment that second stage reuse would come at a payload cost (say 3000 kg for reuse equipment, would mean 10000 kg to orbit)

[strata8]

Where did the 650,000 lbf figure come from in the first place?

[Ben the Space Brit]

I'm not even a moderately knowledgeable armchair expert. However, I'd personally prefer something Falcon-X rather than Falcon-XX class.  This would allow a higher flight rate and maybe bring down costs because the type will be more widely-used.

I'm thinking a 4 x Raptor CCB with a ~5.1m barrel that can be used in single-stick, tri-core and 2-1-2 quin-core configurations; a 2 x Raptor-VAC common dual-use upper stage with every last second of Isp squeezed out of it (the closer to 400s the better).  There would also be an optional 4 x Raptor mid-stage for the heaviest lift configuration. In this 'Super Heavy' configuration, the rocket would have a 7m+ PLF and the mid-stage would have the same barrel diameter as the wide-body PLF. The Super-Heavy would also use the Raptor-VAC upper stage exclusively as an EDS/

The thought of a Falcon-X-Super-Heavy CaLV sitting on LC-39A with a Falcon-X vanilla CLV sitting on LC-39B brings a smile to my face... 

[edit]
More detail; cleared up ambiguities

[go4mars]

I thought this was going to be done at the underground test facility in Texas.  I wonder why they switched.  It doesn't look like a vacuum chamber based on the picture, but I'm assuming the picture is from E-2.

[go4mars]

What would that be to TMI, and how about with three cores?

Echo.

Good questions.

[Elmar Moelzer]

Well, if we are talking what we would like to see... I would like to see the numbers for a VTOL SSTO with those engines. With that thrust, Isp and fuel density, it should be possible to get a reasonable payload into orbit on an relatively(!) compact vehicle.

[Okie_Steve]

I posted this on the methane engine thread, right before this thread was started Probably better here.

There was a lot of discussion recently on the FH  thread about boosters vs core, cross-feed and staging to answer the question asked about why the 3 cores don't cut off at the same time and why the center core would be harder to recover than the boosters. It got me to wondering.

Now this ~4 X Merlin methane engine seems to be materializing from the mists would there in fact be any value to using the a FH in non-cross-fed non-throttled configuration to boost a hypothetical methane second stage or is this "too much" engine to be useful for a second stage?

[AncientU]

Nice speculation, a few notes:

2. Your spreadsheet also references a "75 mT Falcon 9 Heavy Raptor"... ? 

2) 75 mT FH is with a larger (more mass & wider) US with methane/raptor.

I appreciate feedback on the calculations themselves; given my assumptions I believe this performance can be achievable (admittedly close to upper limit of possibility)

This would be an interesting upgrade of the basic FH with crossfeed -- covers the oft-cited weakness of the undersized upper stage, as well as delivering more to LEO.  SLS class, in fact...

[Lars_J]

I think the "FH undersized upper stage" issue is exaggerated. Perhaps additional thrust would be useful for the very heaviest LEO payloads, but for GTO or escape the added thrust would not be useful. (ISP, however...)

[newpylong]

It has only become exaggerated because the armchair community has become fixated on Falcon Heavy being capable of performing Exploration class missions in it's initial configuration (which we all know it is not capable of without multiple launches). The math has been done to show the LEO/GTO (and escape) performance compared to other vehicles and it is a lower percentage. That indicates the upper stage is not taking the best advantage of the first stage, much like the iCPS with SLS. However, it will be capable of performing even the most demanding Commercial or DoD missions out there, which it is designed to do.

[baldusi]

I couldn't find the MCT speculation thread, but it was going kind of wild anyway.

We have a data point now - it seems like a 300 ton Methane engine is in the works.

What will it push?

300,000 kg is one big engine. I wonder how it will be transported.

Let's call it a 2.9MN engine, ok? To put than into perspective, the RD-191, a RG-1/LOX 2.08MN (Vac) engine @ 25.7MPa Pc) has a diameter of 2.1m. The KBKhA RD-0162, a CH4/LOX with 2.00MN (Vac) @ 15.7MPa, has a 3.55m diameter. But, it can do 133% in expendable mode. So we should treat it as a 2.66MN (Vac) @ 20.9MPa. So, it would seem that a 2.9MN CH4/LOX engine could be made to fit into a 3.7m diameter. In fact, since you can ship it in a low tow, you could squeeze a bit more, if necessary. And for the US version, a nozzle extension could be shipped separately. The way they did it with the F-1, was that the engine shipped horizontal, and the nozzle extension was shipped vertically, since the width restrictions for road transport are a lot easier than tall. With that they could add some extra 3.7m of nozzle length.

[oldAtlas_Eguy]

With testing starting in 2014, think about this: it took only 2years for the M1D to go from testing to flight. That would put raptor with a NET flight of late 2016 or early 2017.

That is what is so surprising to me since Iwas not expecting any testing to start for several years putting a flight ready unit out about 2019.   

[Jcc]

I thought this was going to be done at the underground test facility in Texas.  I wonder why they switched.  It doesn't look like a vacuum chamber based on the picture, but I'm assuming the picture is from E-2.

I would guess the answers are: 1) they figure McGregor will be busy with Merlin, Super Draco and stage testing. If they don't need to install methane infrastructure there, it's money saved. 2) Raptor based rockets will need to assembled and tested on the Gulf Coast anyway, due to size. 3) It's cheaper to modify the facilities at Stennis than build a new test facility, and possibly risk complaints due to noise. 4) by doing business in Mississippi, they get 2 more senators and some congressman on their side, besides helping NASA keep their facilities utilized. This last point could be part of a grand scheme to lessen any congressional opposition to a Spacex BFR eventually taking away some heavy launch work from SLS. Maybe even all of it!

[Jason1701]

With testing starting in 2014, think about this: it took only 2years for the M1D to go from testing to flight. That would put raptor with a NET flight of late 2016 or early 2017.

That is what is so surprising to me since Iwas not expecting any testing to start for several years putting a flight ready unit out about 2019.   

I don't think reasoning by analogy works here. They already had experience developing engines similar to M1D, with the same cycle and propellants, whereas everything about Raptor is new.

[oldAtlas_Eguy]

With testing starting in 2014, think about this: it took only 2years for the M1D to go from testing to flight. That would put raptor with a NET flight of late 2016 or early 2017.

That is what is so surprising to me since Iwas not expecting any testing to start for several years putting a flight ready unit out about 2019.   

I don't think reasoning by analogy works here. They already had experience developing engines similar to M1D, with the same cycle and propellants, whereas everything about Raptor is new.

Yes but now have an even more experenced design and test team than they had with M1D. It will take them longer but not 2x longer.

[meekGee]

With testing starting in 2014, think about this: it took only 2years for the M1D to go from testing to flight. That would put raptor with a NET flight of late 2016 or early 2017.

That is what is so surprising to me since Iwas not expecting any testing to start for several years putting a flight ready unit out about 2019.   

I don't think reasoning by analogy works here. They already had experience developing engines similar to M1D, with the same cycle and propellants, whereas everything about Raptor is new.

Yes but now have an even more experenced design and test team than they had with M1D. It will take them longer but not 2x longer.

... and, obviously, today is not day 1.
If the focus shifted gradually from M1D to Raptor, then this development started more than a year ago.
but yes, you were counting 2 years from testing to flight.

I guess we'll start hearing more about the rocket then.
And its launch pad.  Is pad 39 a certainty?  Or will TX offer them sweeteners to bring the big business its way too?

[Chris Bergin]

So basically, we don't know what Raptor is for? Not even confirmed it's for Falcon X?

I asked months ago and got "no one is working on it, answers may take months" (which figured, given SpaceX's very high staff turnover). So is this all spoon fed "we're doing something, but we're not saying what" or SpaceX waiting for easy questions from TrendyTechBlogSite.com to give some more?

TTBS: How big will your rocket be?

SpaceX: Big!

TTBS: Awww, sweet!

"SpaceX - soooo cool - to build big rocket - Exclusive!"

Already had a few shrugged shoulders from some SpaceX people I know.

[meekGee]

So basically, we don't know what Raptor is for? Not even confirmed it's for Falcon X?

We don't.  There were several options that I counted.   
a) a high energy upper stage for FH
b) a single engine replacement for first stage of F9, (the "Merlin 2" scale)
c) a large engine for a BFR, with a similar (7-9) engine count
d) a Mars ascent stage

The ~300 ton number, if correct, narrows it down.

It's too large for option A.
It's too small for option B.
It works well for option C.
It could work for option D.

Much will depend on what MCT turns out to be.  The easy guess is a 4x up-scaled F9 and F9H, but remember Tinker's diagram from a while back?  It had several flaws, but some aspect of it got a nod from Elon.   So a combined US/EDS is possible too.