Author Topic: SpaceX Falcon Heavy Discussion (Thread 3)  (Read 332248 times)

Offline Burninate

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #100 on: 02/23/2015 08:05 pm »
My first stab at a real Falcon Heavy page, after holding out for a while. 
www.spacelaunchreport.com/falconH.html
Comments and criticisms welcomed, because I expect to edit this page substantially this year.  I expect to be surprised when the thing rolls out and we actually see it for the first time.  I also expect to be surprised by how SpaceX actually uses the machine.

 - Ed Kyle
A proposed typology in a few letters:

C) With crossfeed
    Booster cores:
        E) Expendable
        P) Pad
        B) Barge
    Center core:
        E) Expendable
        P) Pad
        B) Barge

W) Without crossfeed
    Booster cores:
        E) Expendable
        P) Pad
        B) Barge
    Center core:
        E) Expendable
        P) Pad
        B) Barge

WEB = Without Crossfeed, Boosters Expendable, Center Core Barge Landing (due to range restrictions? silly example)
CPB = With Crossfeed, Boosters Pad Landing, Center Core Barge Landing (most likely fully reusable config)
CPP = With Crossfeed, Boosters Pad Landing, Center Core Pad Landing (The type I think is currently quoted)

That's 18 possibilities, for which figures are needed to LEO and to GTO, so 36 payload estimates.
« Last Edit: 02/23/2015 08:57 pm by Burninate »

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #101 on: 02/23/2015 08:14 pm »
Crossfeed has been put on the back burner and I wouldn't cover barge for boosters.  I don't think that will be needed, the difference between pad and barge would be in the overall noise.
« Last Edit: 02/23/2015 08:17 pm by Jim »

Offline edkyle99

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #102 on: 02/23/2015 08:52 pm »
Crossfeed has been put on the back burner and I wouldn't cover barge for boosters.  I don't think that will be needed, the difference between pad and barge would be in the overall noise.
While crossfeed may not appear for awhile, if ever, I'll have to include it as a future possibility as long as SpaceX continues to talk about 53 tonnes to LEO and 21.2 tonnes to GTO, since those are crossfeed (fully expendable) numbers.

My guess is that the booster flyback recovery will usually be attempted, but that core recovery attempts (even downrange) may be less frequent because making the core expendable seems to double beyond LEO payload capacity, but I'm just guessing.

 - Ed Kyle
« Last Edit: 02/23/2015 08:56 pm by edkyle99 »

Offline Burninate

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #103 on: 02/23/2015 09:02 pm »
Crossfeed has been put on the back burner and I wouldn't cover barge for boosters.  I don't think that will be needed, the difference between pad and barge would be in the overall noise.
While crossfeed may not appear for awhile, if ever, I'll have to include it as a future possibility as long as SpaceX continues to talk about 53 tonnes to LEO and 21.2 tonnes to GTO, since those are crossfeed (fully expendable) numbers.

My guess is that the booster flyback recovery will usually be attempted, but that core recovery attempts (even downrange) may be less frequent because making the core expendable seems to double beyond LEO payload capacity, but I'm just guessing.

 - Ed Kyle
Unless some phase of flight is extremely ill-posed from a TWR perspective, going from WPB to WPE should *not* double payload capacity, it should be a much lower figure.  It's only with WPP that you get really severe changes, due to the extreme boostback requirements.  The upper stage is heavy enough that the residual fuel needed to land the center core on a barge is not very extreme.
« Last Edit: 02/23/2015 09:20 pm by Burninate »

Offline macpacheco

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #104 on: 02/23/2015 10:34 pm »
How would prop densification and thrust increase improve FH GEO payload with RTLS ?
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Offline Lars-J

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #105 on: 02/23/2015 11:05 pm »

How would prop densification and thrust increase improve FH GEO payload with RTLS ?

I strongly suspect that the FH performance figures already take this thrust upgrade into account.

Offline macpacheco

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #106 on: 02/24/2015 03:19 am »

How would prop densification and thrust increase improve FH GEO payload with RTLS ?

I strongly suspect that the FH performance figures already take this thrust upgrade into account.
Falcon Heavy was announced in 2011-04, with Elon quoting 53 tons to LEO. Are you telling us this was in the plans since almost 4 years ago ?

And people say SpaceX doesn't have foresight, that it doesn't plan far out into the future...
When the first FH mission launches, we should be able to get answers about what FH can do without cross feed but with side boosters RTLS + center core barge landing.
Maybe we should have a pool for when the first successful FH launch will happen. Month by month, starting June 2015 I suggest. I would bet September 2015.
« Last Edit: 02/24/2015 03:24 am by macpacheco »
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Offline PahTo

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #107 on: 02/24/2015 01:58 pm »

Ed's article implies an (uprated?) Merlin 1D in the offing, yet I thought the 1D has been flying for some time now in its "final" form.  Is there in fact an uprated version of the 1D yet to fly?

Offline Kabloona

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #108 on: 02/24/2015 02:01 pm »

Ed's article implies an (uprated?) Merlin 1D in the offing, yet I thought the 1D has been flying for some time now in its "final" form.  Is there in fact an uprated version of the 1D yet to fly?

It is in final form, but they have only been running at it 85% throttle. Beginning with SES-9 they will run at full throttle. More here:

http://forum.nasaspaceflight.com/index.php?topic=32983.220
« Last Edit: 02/24/2015 02:03 pm by Kabloona »

Offline PahTo

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #109 on: 02/24/2015 02:09 pm »

Thanks--that thread now bookmarked.
I suspect we'd see high(er) energy upper stage before/in lieu of cross-feed, but time will tell...

Offline edkyle99

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #110 on: 02/25/2015 12:40 am »
I've been looking at Falcon Heavy possibilities a bit.  The main puzzle is, and has long been, the SpaceX statement that the Heavy GLOW is 1,463 tonnes, while Falcon 9 v1.1 GLOW is only 506 tonnes.  If you put Falcon 9 v1.1 pieces together as a first guess to build a Heavy, you only get a GLOW of 1358 tonnes or so. 

But even that rocket can get 45 tonnes to LEO and more than 15 tonnes to GTO in expendable mode (no crossfeed is assumed for any of my figuring right now).   If the boosters and cores are recovered, and if 35 tonnes of recovery propellant is assumed for each, the numbers drop to 26 tonnes LEO and a bit more than 7 tonnes GTO, the latter of which lines up well with the 6.4 tonnes advertised capability.  Expending the core but recovering the boosters gives 34 tonnes LEO and 11 tonnes GTO.

That missing 100 tonnes GLOW could be packed into the rocket in several ways.  One guess was that the boosters would be stretched a bit to carry more propellant than the core stage, which works out to improve the beyond-LEO expendable numbers a bit (GTO goes up to 17 tonnes full expendable, but is still only 8 tonnes or so for full recovery).  Propellant densification could increase the mass of all three cores with similar results.

So there is my thinking at present, all in flux.

Now, about prices and costs, note that the current going rate to GTO is about $13 million per tonne.  Thus, SpaceX would seem to be giving up $104 million of potential income when it recovers all three cores rather than expending them.  Do three core stages cost more than $104 million?

 - Ed Kyle
« Last Edit: 02/25/2015 12:58 am by edkyle99 »

Offline S.Paulissen

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #111 on: 02/25/2015 12:57 am »
Out of curiosity, what have you included as variables in your simulations?
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Offline TrueBlueWitt

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #112 on: 02/25/2015 01:03 am »
I've been looking at Falcon Heavy possibilities a bit.  The main puzzle is, and has long been, the SpaceX statement that the Heavy GLOW is 1,463 tonnes, while Falcon 9 v1.1 GLOW is only 506 tonnes.  If you put Falcon 9 v1.1 pieces together as a first guess to build a Heavy, you only get a GLOW of 1358 tonnes or so. 

But even that rocket can get 45 tonnes to LEO and more than 15 tonnes to GTO in expendable mode (no crossfeed is assumed for any of my figuring right now).   If the boosters and cores are recovered, and if 35 tonnes of recovery propellant is assumed for each, the numbers drop to 26 tonnes LEO and a bit more than 7 tonnes GTO, the latter of which lines up well with the 6.4 tonnes advertised capability.  Expending the core but recovering the boosters gives 34 tonnes LEO and 11 tonnes GTO.

That missing 100 tonnes GLOW could be packed into the rocket in several ways.  One guess was that the boosters would be stretched a bit to carry more propellant than the core stage, which works out to improve the beyond-LEO expendable numbers a bit (GTO goes up to 17 tonnes full expendable, but is still only 8 tonnes or so for full recovery).  Propellant densification could increase the mass of all three cores with similar results.

So there is my thinking at present, all in flux.

Now, about prices and costs, note that the current going rate to GTO is about $20 million per tonne.  Thus, SpaceX would seem to be giving up $160 million of potential income when it recovers all three cores rather than expending them.  Do three core stages cost more than $160 million?

 - Ed Kyle

Ed, is that's with Merlin-1D at 85% or 100%? 

There has also talk that S2 has been flying with propellant offload on F9 1.1.. Could that be part of the mass delta? 

I will be very curious to see if GLOW goes up for SES-9 with F9 using 100% M1D (Assume will fly without prop densification?).. that would mean they're flying with more prop in S2

Flying heavier prop load in S2(if possible) would mean lower staging and less boost-back prop mass required.. Also if they fly uprated M1DV@100% at 200klb that would offset Grav losses for S2 even with the extra prop.
« Last Edit: 02/25/2015 01:06 am by TrueBlueWitt »

Offline edkyle99

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #113 on: 02/25/2015 02:23 am »
Out of curiosity, what have you included as variables in your simulations?
Constraints are:  GLOW < 1463 tonnes, Boosters = Stage 1 (PMF = 0.95), Stage 2 propellant mass = Stage 1 propellant mass/4.45 (PMF = 0.94), T/W Stage 2 > 0.55 or so,  Core propellant at booster burnout = recovery propellant if any + 20% of liftoff load, 0.5% residuals, 9,200 m/s for LEO, 11,700 m/s for GTO.  My variables are the stage gross masses.

 - Ed Kyle
« Last Edit: 02/25/2015 02:32 am by edkyle99 »

Offline edkyle99

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #114 on: 02/25/2015 02:29 am »

Ed, is that's with Merlin-1D at 85% or 100%? 

There has also talk that S2 has been flying with propellant offload on F9 1.1.. Could that be part of the mass delta? 
I've assumed current thrust levels, but it doesn't matter much because there is plenty of thrust even for the heavier SpaceX GLOW.  Stage 2 propellant loading could explain some of the 100 tonnes, but not, I think, all of it.  The stage "wants" to gross about 100 tonnes or less to work well beyond-LEO, and it can offload propellant from its GTO type loadings for LEO missions.

 - Ed Kyle

Offline Lars-J

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #115 on: 02/25/2015 06:19 am »

That missing 100 tonnes GLOW could be packed into the rocket in several ways.  One guess was that the boosters would be stretched a bit to carry more propellant than the core stage, which works out to improve the beyond-LEO expendable numbers a bit (GTO goes up to 17 tonnes full expendable, but is still only 8 tonnes or so for full recovery).  Propellant densification could increase the mass of all three cores with similar results.

Several SpaceX illustrations have shown longer boosters, so it is more than a guess. And we know they are talking densification as an imminent upgrade (perhaps even as early as SES-9), so that seems pretty clear to explain some of it.

Offline cscott

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #116 on: 02/25/2015 06:55 am »
Seems like no one thing accounts for the full 100 tons, but if you combine all three (propellant densification, booster stretch, increased S2 loading) you might get pretty close?

Offline Lars-J

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #117 on: 02/25/2015 03:31 pm »
Seems like no one thing accounts for the full 100 tons, but if you combine all three (propellant densification, booster stretch, increased S2 loading) you might get pretty close?

The S2 not launching full on F9 is just forum speculation, and non-sensical forum speculation at that. Don't believe it.
« Last Edit: 02/25/2015 03:33 pm by Lars-J »

Offline Owlon

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #118 on: 02/25/2015 09:14 pm »
Seems like no one thing accounts for the full 100 tons, but if you combine all three (propellant densification, booster stretch, increased S2 loading) you might get pretty close?

The S2 not launching full on F9 is just forum speculation, and non-sensical forum speculation at that. Don't believe it.

I wouldn't discount a S2 stretch for FH, but, yeah, leaving it partially fueled for regular F9 launches does seem improbably to me.

Online TomH

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #119 on: 02/25/2015 09:49 pm »
One guess was that the boosters would be stretched a bit to carry more propellant than the core stage

If that's without cross-feed and no reusability or disposable boosters and reusable core then you're really going to have to have the boosters running at a considerably higher throttle than the core. Otherwise the core runs out of prop before the boosters do. That's pretty problematic!  :o

With cross-feed, having boosters longer than the core makes sense, assuming core is fed by booster tanks only until booster jetison, at which time core begins feeding from its own full tanks.

Your configuration could also work if you have reusable boosters and disposable core, but then you're shutting down all 3 at about the same time. In that case, why have simultaneous MECO on all 3, yet dispose of 1 and recover 2?
« Last Edit: 02/25/2015 09:56 pm by TomH »

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