Author Topic: LIVE: SpaceX: Falcon Heavy Thread - April 5 announcement  (Read 263481 times)

Offline kevin-rf

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Re: SpaceX: Falcon Heavy Thread
« Reply #40 on: 04/03/2011 03:04 PM »
Wel i think it would be that, however you never know they might have something in the background like a FH look alike, you know a couple of F9's laid out to look like a FH

A full scale falcon heavy would be awesome. Doesn't have to be three F9's, it could be a falcon heavy pathfinder. One that is never ment to fly... Kinda like the first cape Falcon 9. SpaceX does have a history of producing those.

btw. I really hope they give us an update on what is happening with the 1e.
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Offline zaitcev

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Re: SpaceX: Falcon Heavy Thread
« Reply #41 on: 04/03/2011 04:40 PM »
Is it certain that the strap ons will be jettisoned? Or will the three cores operate together as a single stage like Rus M? (Of course the cores might be separated after staging to allow for single recovery if this proves worthwhile.)
If the center core can throttle down without losing too much Isp, or if they install 5 engines on it, the payload is going to grow significantly. As for the Rus-M (the winner of SKPG tender), that design only came about because of the guaranteed take-off requirement. It is basically a LAS for the whole launcher. Hardly an instructive example, IMHO.

Offline zaitcev

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Re: SpaceX: Falcon Heavy Thread
« Reply #42 on: 04/03/2011 04:43 PM »
BTW, one other thing they could propose is "Falcon 45" or "Falcon Very Heavy" - 5 cores. The projected outline in the video matches :-)

Offline go4mars

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Re: SpaceX: Falcon Heavy Thread
« Reply #43 on: 04/03/2011 05:02 PM »
BTW, one other thing they could propose is "Falcon 45" or "Falcon Very Heavy" - 5 cores. The projected outline in the video matches :-)

I don't think that this outline would match a 5 core version.  The outlines would likely overlap instead of having a gap of free space between the cores.  But I suppose it is possible as you see it.

I'm guessing the announcement is about vanilla FH, which is fine by me.  Cross-feeding and 5 core versions are probably a long way off imo.  It is possible that they could announce that the pad will be made to accomodate a 5 core variant, a 3 core variant, and single core variant, but I doubt it. 

Yet... If they are planning to have their pad up and running in 2 years, and if it could accomodate a 5 core version, it just might be the fastest way for the US gov't to get 70 tons to orbit at once.   

It is also possible that they threw in the outline to make everyone guess FH, when in fact they will announce F-X or F-XX.  Perhaps an oil baron from Saudi finally wants a castle in the sky.   Wildly optimistic I know...
« Last Edit: 04/03/2011 05:07 PM by go4mars »
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Offline zaitcev

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Re: SpaceX: Falcon Heavy Thread
« Reply #44 on: 04/03/2011 05:43 PM »
I don't think that this outline would match a 5 core version.  The outlines would likely overlap instead of having a gap of free space between the cores.  But I suppose it is possible as you see it.
I meant a configuration with 90 degree spacing between side cores, like on Soyuz, and not 60 degree spacing like on Angara. That would project cleanly...

Offline kevin-rf

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Re: SpaceX: Falcon Heavy Thread
« Reply #45 on: 04/03/2011 05:55 PM »
I don't know, I only counted 9 engines, not 27 ;)
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Offline robertross

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Re: SpaceX: Falcon Heavy Thread
« Reply #46 on: 04/03/2011 06:02 PM »
I don't know, I only counted 9 engines, not 27 ;)

I count a minimum of 15 engines, assuming 5 engines for the core & each booster. The engine fairings sort of give that away  ;)


edit to add: that's assuming this B&W litho is close (or representative) of the F9H colour illustration on the previous page.
« Last Edit: 04/03/2011 06:03 PM by robertross »
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Offline douglas100

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Re: SpaceX: Falcon Heavy Thread
« Reply #47 on: 04/03/2011 06:06 PM »
From zaitcev:

Quote
If the center core can throttle down without losing too much Isp, or if they install 5 engines on it, the payload is going to grow significantly.

What interests me here is how much payload gain there is compared with a non-separating core version. The centre core can be throttled down by shutting down engines, but restarting them to bring the thrust up after core separation (like Delta IVH) would certainly complicate things. Alternatively the current first stage Merlin engines could of course be made throttleable.

I can't find any indication on SpaceX's web site how they intend to operate the vehicle. By keeping the cores together until staging they would reduce the separation events needed to ensure mission success by one (or maybe two, depending how you look at it). Against this is the performance loss. I don't know how much that would be.

Can anyone shed any light on this?
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Offline Halidon

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Re: SpaceX: Falcon Heavy Thread
« Reply #48 on: 04/03/2011 07:51 PM »
Can anyone shed any light on this?
I'd expect SpaceX to have a slick little video of a simulated FH launch during their event Tuesday. Should answer how they are currently envisioning staging.

Offline Jason1701

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Re: SpaceX: Falcon Heavy Thread
« Reply #49 on: 04/03/2011 09:33 PM »
From zaitcev:

Quote
If the center core can throttle down without losing too much Isp, or if they install 5 engines on it, the payload is going to grow significantly.

What interests me here is how much payload gain there is compared with a non-separating core version. The centre core can be throttled down by shutting down engines, but restarting them to bring the thrust up after core separation (like Delta IVH) would certainly complicate things. Alternatively the current first stage Merlin engines could of course be made throttleable.

I can't find any indication on SpaceX's web site how they intend to operate the vehicle. By keeping the cores together until staging they would reduce the separation events needed to ensure mission success by one (or maybe two, depending how you look at it). Against this is the performance loss. I don't know how much that would be.

Can anyone shed any light on this?

Maybe Merlin 1D is designed to be throttleable from the start.

Offline arnezami

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Re: SpaceX: Falcon Heavy Thread
« Reply #50 on: 04/03/2011 09:41 PM »
So 5 engines right?

Name 'm.

Offline Dave G

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Re: SpaceX: Falcon Heavy Thread
« Reply #51 on: 04/03/2011 09:52 PM »
...Any ideas on altitude of/velocity of FH strap ons when they are "jettisoned? 
Depends of whether they're cross fed.

Online nacnud

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Re: SpaceX: Falcon Heavy Thread
« Reply #52 on: 04/03/2011 10:01 PM »
So 5 engines right?

Name 'm.

Kestrel, merlin 1a, merlin 1c, merlin vac, draco,

Offline douglas100

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Re: SpaceX: Falcon Heavy Thread
« Reply #53 on: 04/03/2011 10:43 PM »
Thanks for the comments. I'm skeptical about cross feed, though.
« Last Edit: 04/03/2011 11:00 PM by douglas100 »
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Offline spacetraveler

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Re: SpaceX: Falcon Heavy Thread
« Reply #54 on: 04/03/2011 10:57 PM »
If they only put 5 engines on the core stage, wouldn't that add to the cost since it would decrease commonality in processing and development for the cores and add complexity?
« Last Edit: 04/03/2011 10:57 PM by spacetraveler »

Offline Rhyshaelkan

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Re: SpaceX: Falcon Heavy Thread
« Reply #55 on: 04/04/2011 06:18 AM »
With a test firing in 2012, I hope they do something with it. Launch a dead 32000kg block of steel, a tank of water weighing 32000kg, or something similar, to prove the capability. It seems that they have not pushed the upper limits of their rockets capability yet. Numbers on paper are just that.
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Offline sdsds

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Re: SpaceX: Falcon Heavy Thread
« Reply #56 on: 04/04/2011 06:35 AM »
If they only put 5 engines on the core stage, wouldn't that add to the cost since it would decrease commonality in processing and development for the cores and add complexity?

Are you suggesting there would be significant costs in removing four engines and their associated plumbing?

Without even looking at the numbers I'm betting they announce a Merlin-1D "959" configuration, still claiming "single engine out" capability right from the pad.
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Offline Ben the Space Brit

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Re: SpaceX: Falcon Heavy Thread
« Reply #57 on: 04/04/2011 07:17 AM »
A lot waits on tomorrow's big unveil.  I'm wondering if the core will be longer than the outriggers.  That way, it burns longer without needing to work out how to make Merlin-1d throttle.
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Offline MP99

Re: SpaceX: Falcon Heavy Thread
« Reply #58 on: 04/04/2011 07:52 AM »
A lot waits on tomorrow's big unveil.  I'm wondering if the core will be longer than the outriggers.  That way, it burns longer without needing to work out how to make Merlin-1d throttle.

Referring to this this dicussion, right?

I've been wondering about this, too. F9 kills two engines at the end of it's first stage burn. (NB this isn't engine-out, just "throttling" the core down to 7/9ths of full thrust). I presume it would need to kill multiple engines in the Heavy config to keep T/W down.

Is it possible this config only kills core engines, presumably in pairs, as the vehicle repeatedly reaches it's T/W limit? In this way, the outriggers would need a greater prop load to burn out at the same time.

There has been talk that Merlin 1D is optimised with a core stretch. Could we be looking at a Block-I-standard central core (with 1D's, so greater T/W), with stretched outriggers?

At lift-off, the central core is carrying extra payload in place of extra prop. Meanwhile the extra prop in the outriggers gives similar T/W on all three cores, minimising stresses at liftoff.

Obviously, "throttling" (kill engines) would happen much earlier in the flight than happens with standard F9. Once this happens, the lower prop consumption rate would then increase the force being transferred from the outriggers to the central core.

cheers, Martin



Offline MikeAtkinson

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Re: SpaceX: Falcon Heavy Thread
« Reply #59 on: 04/04/2011 09:07 AM »
The strategies are as I see it:

1. Use three cores with minimal changes from F9 block II, throttle each down at the same time by shutting down two engines. All cores burn out at the same time, there is one separation event.

2. Use three cores with minimal changes from F9 block II, throttle down  only the middle core by shutting down 2, then 4 then 6 engines engines. The strap-ons burn out first, separate and the centre core continues on for a time on 3 engines.

3. Use three cores with minimal changes from F9 block II, throttle down  the middle core by shutting down 4 engines engines, and each strap-on by a single engine. The strap-ons burn out first, separate and the centre core continues on for a time on 5 engines.

4. lengthen the middle core and shorten the strap-ons, do not shut down any engines. Separate the strap-ons when they burn out and the centre core continues on for a time on all 9 engines.

5. Put only 5 engines on the middle core, all cores have the same propellant load so the strap-ons burn out first and separate.

6.  Put only 5 engines on the middle core, adjust the propellant load so all cores burn out at the same time.

7. Put only 5 engines on the middle core, adjust the propellant load so the strap-ons burn out first (earlier than in 5) and separate.

8. Cross-feed propellant so that when the strap-ons burn out and separate the centre tanks are full (or nearly so).

As F9 block II has 10.5 tonne to LEO, you would expect strategy 1 to be able to launch just over 3x that (assuming an optimised upper stage), due to some efficiencies in a triple core vehicle (single avionics suite, single payload adapter, etc.). This would give ~32 tonne to LEO.

I would expect strategies 2, 3 and 4 to give progressively more payload with strategy 4 having maybe 20% more (again assuming optimised upper stage).

I would expect strategy 5 to have less than 32 tonne payload, with strategy 7 up to approximately 32 tonne again. Using less engines may reduce the cost (and hence decrease $/kg over strategy 1).

Strategy 8 would give the best payload by a considerable margin. It does however involve significant changes to the cores.

Given that they are advertising 32 tonne payload capability I think they will be using strategy 1, with potential growth path to strategy 4 and then 8.

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