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SpaceX Vehicles and Missions => SpaceX Mega Thread Archive Section => Topic started by: Chris Bergin on 02/16/2015 12:18 PM

Title: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Chris Bergin on 02/16/2015 12:18 PM
New thread for FH!

Thread 1:
http://forum.nasaspaceflight.com/index.php?topic=32528.0

Thread 2:
http://forum.nasaspaceflight.com/index.php?topic=35365.0

Main FH Articles:
http://www.nasaspaceflight.com/2011/04/spacex-falcon-heavy-tag-team-share-20-launches-year/

http://www.nasaspaceflight.com/2013/05/from-atlas-v-falcon-xx-commercial-suitors-wanted-pad-39a/

http://www.nasaspaceflight.com/2014/07/spacex-roadmap-rocket-business-revolution/

http://www.nasaspaceflight.com/2014/11/pad-39a-spacex-groundwork-falcon-heavy-debut/


SpaceX news articles on this site:
Old: http://forum.nasaspaceflight.com/index.php?topic=21862.0 (links)

Then recent news articles, not linked above, as we moved to a tag group system:
All recent: http://www.nasaspaceflight.com/tag/spacex/


L2 SpaceX - Dedicated all-vehicle section - including a mass of new amazing renderings we've created.
http://forum.nasaspaceflight.com/index.php?board=60.0


NOTE: Posts that are uncivil (which is very rare for this forum), off topic (not so rare) or just pointless will be deleted without notice.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim_LAX on 02/16/2015 01:57 PM
I think we WILL see an FH on the pad in its transporter/erector before the end of this year, at least for purposes of fit and function tests similar to the first F9.  As to weather it lifts off from that pad I give it a 50:50 chance (this year).  As an optimist, yes I would love to see it fly.  SpaceX would certainly earn serious points for quality of design/construction if the first FH flight launched a payload worthy of its published performance specs!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: symbios on 02/16/2015 02:25 PM
I know there are a lot of different issues that is causing the delay in FH launch.

I wonder how big an issue recovery is for SpaceX, if their project plans is to have the launch right after they feel recovery is plausible. It would save a lot of cost...?

FH is no use to them if they can not recover. They can not start AF licensing until they have the flight ready version etc., etc.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Bynaus on 02/16/2015 02:50 PM
I think we will see a FH debut only after SpaceX has landed a F9 booster at the Cape (RTLS). They will attempt to recover all three boosters of the FH Demo flight. There is simply no good reason to speed up the FH Demo flight (except us waiting for it... :) ) if they can wait just a little bit longer and save a lot of money doing so - even gain additional experience in core recovery and the possibility to inspect the Heavy cores after flight.

And I think Elon's MCT announcement will only be made once FH Demo has flown without flaws.

Is there any chance (available DV-wise) we might see a lunar free return flight of a used Dragon in the FH Demo? Perhaps to be unveiled only once the Dragon is safely on its way to the Moon? I see this as a real possibility because it would be quite an inspiring symbol: America is back in business sending human-capable spacecraft beyond LEO!

EDIT: clarification that I meant a lunar free return flight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Billium on 02/16/2015 03:32 PM
In a perfect world Spacex might want to wait for the FH demo until they could demo everything with it at the same time, ie. improved Merlin thrust, dense fuel, cross feed, landing all 3 cores, reusing a core. The cost of the demonstration will be very high, so might as well get as much bang for your buck.

On the other hand, Spacex has sold FH flights which were already shown in the manifest as 2015. I think they don’t really have the option of waiting much longer past Q4, 2015 and need to fly their demo as soon as they are ready for it, even if they can only recover 1 core. Also, if they want to get military certification for FH by the end of the block buy they need to get moving.

As to Dragon on a lunar free return, Gwynne Shotwell answered my question on the Space Show by saying that FH had the deltaV for this, but that Dragon would need improved communications. I don’t know if she meant FH would need cross feed, improved Merlin thrust or fuel densification.

I think Spacex has likely been holding off doing anything that is seen as competing with SLS/Orion until they got past commercial crew selection. Sending Dragon around the moon Q4, 2015, would be 3 years before Orion does the same thing, so definitely that is a challenge. But by Q4, 2015 commercial crew should be far enough along that even a challenge to SLS/Orion is unlikely to cause commercial crew cancelation, so maybe this would be a good PR move for Spacex. Elon did announce that they would hopefully unveil their Mars architecture by the end of 2015 so perhaps this is not impossible.

Also, if Spacex refurbishes a used Dragon, it would be a great opportunity to test the heat shield for a higher energy return. Spacex have stated the heat shield is good for Mars return, it would be nice to demonstrate it. If they are paying for 3 cores anyways, might as well use it for something else at the same time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/16/2015 04:09 PM
I think we will see a FH debut only after SpaceX has landed a F9 booster at the Cape (RTLS). They will attempt to recover all three boosters of the FH Demo flight. There is simply no good reason to speed up the FH Demo flight (except us waiting for it... :) ) ...
That's not true. There's a big portion of the launch market, the part with the most revenue in it (or at least comparable to F9's market), that can't be addressed until Falcon Heavy has flown.

The sooner they fly Falcon Heavies, the sooner they can compete for all the defense payloads. F9 can only serve about half of those, and the revenue on that lighter half is significantly less than the heavier half.

There are also a lot of commercial payloads which they can't compete for without Falcon Heavy, the highest revenue commercial payloads.


...lots of very good reasons to speed up the Falcon Heavy Demo (although even more crucial will be ensuring it launches without major failure). They may still do the FH flight after the first RTLS F9s, but that's a different issue. (I personally think FH probably won't launch until 2016.)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Bynaus on 02/16/2015 04:49 PM
I think we will see a FH debut only after SpaceX has landed a F9 booster at the Cape (RTLS). They will attempt to recover all three boosters of the FH Demo flight. There is simply no good reason to speed up the FH Demo flight (except us waiting for it... :) ) ...
That's not true. There's a big portion of the launch market, the part with the most revenue in it (or at least comparable to F9's market), that can't be addressed until Falcon Heavy has flown.

The sooner they fly Falcon Heavies, the sooner they can compete for all the defense payloads. F9 can only serve about half of those, and the revenue on that lighter half is significantly less than the heavier half.

There are also a lot of commercial payloads which they can't compete for without Falcon Heavy, the highest revenue commercial payloads.


...lots of very good reasons to speed up the Falcon Heavy Demo (although even more crucial will be ensuring it launches without major failure). They may still do the FH flight after the first RTLS F9s, but that's a different issue. (I personally think FH probably won't launch until 2016.)

Yes, these are good points. But then, competing for defense payloads means going for certification, and this means you need to have a near-final version of the vehicle you want to certify ready, otherwise the clock is reset every time you re-introduce a new feature (e.g., cross-feed, fuel densification, uprated Merlins, RTLS etc.). From this point of view, it might be better to have all that ready for FH Demo, which will take time. On the other hand, if a "basic" version of FH will do for defense payloads (and I assume it will, given the payload mass of even the most basic FH exceeds the Delta IV Heavy), it might pay to go forward quickly with an initial version and certify the "full" FH later.

But I agree that we might have to wait until next year to see it fly. Which, I think, also means no MCT announcement this year. Because this is the way things have always been with SpaceX and Elon Musk: they always achieve a big milestone before they announce the next big thing.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 02/16/2015 06:00 PM
I think we will see a FH debut only after SpaceX has landed a F9 booster at the Cape (RTLS). They will attempt to recover all three boosters of the FH Demo flight. There is simply no good reason to speed up the FH Demo flight (except us waiting for it... :) ) ...
That's not true. There's a big portion of the launch market, the part with the most revenue in it (or at least comparable to F9's market), that can't be addressed until Falcon Heavy has flown.

The sooner they fly Falcon Heavies, the sooner they can compete for all the defense payloads. F9 can only serve about half of those, and the revenue on that lighter half is significantly less than the heavier half.

There are also a lot of commercial payloads which they can't compete for without Falcon Heavy, the highest revenue commercial payloads.


...lots of very good reasons to speed up the Falcon Heavy Demo (although even more crucial will be ensuring it launches without major failure). They may still do the FH flight after the first RTLS F9s, but that's a different issue. (I personally think FH probably won't launch until 2016.)

This.

They have lots of reasons to want to get FH flying as soon as they can.  Their full Falcon business model can't go into effect until that happens.  This summer may be too optimistic but we'll see.  They won't rush it and unnecessarily risk a launch failure, but I think they are busting arse as much as they can to get it flying.  Untill it's flying, Elon can only hammer on ULA so much, because he doens't have comparable capability.  ULA is still the only US launch provider than can launch the heavier defense payloads.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Zed_Noir on 02/16/2015 06:06 PM
@Blackstar posted some interesting tidbits about the Falcon Heavy in the "Proposed Europa Missions" thread.

Quote
...
Falcon Heavy is not using cross-feed. They're not developing it. I was at SpaceX several months ago and asked about cross-feed and was told by one of the people working on the rocket that they are not developing it.
...
link (http://forum.nasaspaceflight.com/index.php?topic=27871.msg1332228#msg1332228)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/16/2015 06:12 PM
@Blackstar posted some interesting tidbits about the Falcon Heavy in the "Proposed Europa Missions" thread.

Quote
...
Falcon Heavy is not using cross-feed. They're not developing it. I was at SpaceX several months ago and asked about cross-feed and was told by one of the people working on the rocket that they are not developing it.
...
link (http://forum.nasaspaceflight.com/index.php?topic=27871.msg1332228#msg1332228)

Interesting indeed. We should know by the end of this year whether or not it was accurate or a misunderstanding.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 02/16/2015 06:14 PM
Hopefully this is the right thread for this question.

Has SpaceX said anything for sure about if they plan to upgrade LC-40 to handle FH?

I'd assume they would, perhaps after 39A is up and fully functional becuase an upgrade to LC-40 like that will mean it'll be out of commission for awhile, and their manifest is packed right now.

But I don't recall anything for sure about it, other than an old comment by Elon saying they might build a FH HIB at a 90 degree angle to the F9 HIB.  I think that was before 39A was in the mix, so they could keep flying F9 while upgrading to FH.  With 39A operational, I think they can just fly from there and tear down the F9 HIB and build the FH HIB there

Or will they just leave LC-40 launching F9 only?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deltaV on 02/16/2015 06:18 PM
From the Europa science thread Blackstar posted some juicy Falcon Heavy info:

Back in October I had lunch sitting next to a guy from Aerojet who was working on an upper stage for (I think) Falcon Heavy to enable SpaceX to compete for the Solar Probe Plus mission. Dunno if that's gone public anywhere, but it may be mentioned elsewhere on this site. Anyway, they're locked out of a number of missions unless they upgrade their hardware.

I wonder what sort of fuel that upper stage would use. Aerojet Rocketdyne has a suitable hydrogen engine (RL-10), various hypergolic engines (e.g. Shuttle OMS) and solids experience (e.g. Orion FTS jettison motor) so there are a lot of plausible options.

If that guy's project is official it sounds like Aerojet Rocketdyne is trying to build a future for itself that doesn't rely on ULA. I was going to write that this was surprising back-stabbing of its close business partner ULA but then I remembered that ULA has already cheated on that marriage with their funding of XCOR's RL-10 competitor.

Quote
One other thing: Falcon Heavy is not using cross-feed. They're not developing it. I was at SpaceX several months ago and asked about cross-feed and was told by one of the people working on the rocket that they are not developing it. It's a potential upgrade if somebody pays for it, but they're not doing the development. So you shouldn't use it in your calculations.

Without cross feed Falcon Heavy can send 45 tonnes to LEO according to http://www.spacex.com/falcon-heavy. I suppose that's the best estimate of Falcon Heavy performance to LEO we have currently?

SpaceX's plans for the heaviest payloads involve the BFR so it makes sense that they don't see a need to optimize FH's capacity.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/16/2015 06:19 PM
Hopefully this is the right thread for this question.

Has SpaceX said anything for sure about if they plan to upgrade LC-40 to handle FH?

I'd assume they would, perhaps after 39A is up and fully functional becuase an upgrade to LC-40 like that will mean it'll be out of commission for awhile, and their manifest is packed right now.

But I don't recall anything for sure about it, other than an old comment by Elon saying they might build a FH HIB at a 90 degree angle to the F9 HIB.  I think that was before 39A was in the mix, so they could keep flying F9 while upgrading to FH.  With 39A operational, I think they can just fly from there and tear down the F9 HIB and build the FH HIB there

Or will they just leave LC-40 launching F9 only?

They have mentioned doing it, but plans change, and most of those comments were pre-39A acquisition. Now that they have 39A I don't see them being in a hurry do it. Perhaps never. But it also depends on two additional factors:
 - What will be the ratio of F9 to FH launches going forward?
 - How quickly will the Texas launch pad come online (presumably built to support FH from the beginning)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: LastStarFighter on 02/16/2015 06:25 PM
Hopefully this is the right thread for this question.

Has SpaceX said anything for sure about if they plan to upgrade LC-40 to handle FH?

I'd assume they would, perhaps after 39A is up and fully functional becuase an upgrade to LC-40 like that will mean it'll be out of commission for awhile, and their manifest is packed right now.

But I don't recall anything for sure about it, other than an old comment by Elon saying they might build a FH HIB at a 90 degree angle to the F9 HIB.  I think that was before 39A was in the mix, so they could keep flying F9 while upgrading to FH.  With 39A operational, I think they can just fly from there and tear down the F9 HIB and build the FH HIB there

Or will they just leave LC-40 launching F9 only?

They did originally have a plan for it like you said... My guess is that once they got LC39A that plan got put on hold for now. The question becomes will the have a need for two heavy launch pads in Florida? If they do I'm sure they can have some down time on LC40 since they'd have LC39A to take up the slack.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deltaV on 02/16/2015 07:04 PM
I wonder if the Aerojet guy that Blackstar ate lunch next to was working on the NASA project to build a common upper stage discussed in this thread: http://forum.nasaspaceflight.com/index.php?topic=35144 . Or maybe this Falcon Heavy upper stage project evolved out of that NASA-funded project?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/16/2015 07:23 PM
I think we will see a FH debut only after SpaceX has landed a F9 booster at the Cape (RTLS). They will attempt to recover all three boosters of the FH Demo flight. There is simply no good reason to speed up the FH Demo flight (except us waiting for it... :) ) ...
That's not true. There's a big portion of the launch market, the part with the most revenue in it (or at least comparable to F9's market), that can't be addressed until Falcon Heavy has flown.

The sooner they fly Falcon Heavies, the sooner they can compete for all the defense payloads. F9 can only serve about half of those, and the revenue on that lighter half is significantly less than the heavier half.

There are also a lot of commercial payloads which they can't compete for without Falcon Heavy, the highest revenue commercial payloads.


...lots of very good reasons to speed up the Falcon Heavy Demo (although even more crucial will be ensuring it launches without major failure). They may still do the FH flight after the first RTLS F9s, but that's a different issue. (I personally think FH probably won't launch until 2016.)

Yes, these are good points. But then, competing for defense payloads means going for certification, and this means you need to have a near-final version of the vehicle you want to certify ready, otherwise the clock is reset every time you re-introduce a new feature (e.g., cross-feed, fuel densification, uprated Merlins, RTLS etc.). From this point of view, it might be better to have all that ready for FH Demo, which will take time.  ...
You know, people keep saying that, neglecting the fact that both Atlas V and Delta IV have flown MANY variants:

First, there are many different numbers of SRBs that are flown (and with Delta IV Heavy, two more cores!). Each one has slightly different flight characteristics, aero-acoustic loads, etc. Then, there are the several different fairing types that are flown, on Atlas V one that covers the upper stage and another that doesn't and is much bigger. On Delta IV, you even have two different upper stages! Not to mention the new, upgraded R-68A.

I just don't buy that SpaceX somehow has a lot more vehicle variants than ULA does. Adding fins and legs is a much smaller change for the main mission's flight characteristics than, say, adding a few SRBs.

So unless someone can point to me where ULA has had to recertify when they make a change (which is a possibility, though I'm not aware of it), then I don't buy that SpaceX has to start from scratch if they upgrade Merlin 1D or add some propellant densification. And certainly, RTLS happens AFTER the main mission is over for the boosters, so it wouldn't affect certification (particularly if they fly with legs/fins regardless, which seems reasonably likely).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 02/16/2015 07:45 PM
If that guy's project is official it sounds like Aerojet Rocketdyne is trying to build a future for itself that doesn't rely on ULA. I was going to write that this was surprising back-stabbing of its close business partner ULA but then I remembered that ULA has already cheated on that marriage with their funding of XCOR's RL-10 competitor.

Not only the RL-10 competitor, but ULA partnered with Blue Origin for the RD-180 replacement instead of going with Aerojet.

No exclusivity between Aerojet and ULA...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrevorMonty on 02/16/2015 08:45 PM
From the Europa science thread Blackstar posted some juicy Falcon Heavy info:

Back in October I had lunch sitting next to a guy from Aerojet who was working on an upper stage for (I think) Falcon Heavy to enable SpaceX to compete for the Solar Probe Plus mission. Dunno if that's gone public anywhere, but it may be mentioned elsewhere on this site. Anyway, they're locked out of a number of missions unless they upgrade their hardware.

I wonder what sort of fuel that upper stage would use. Aerojet Rocketdyne has a suitable hydrogen engine (RL-10), various hypergolic engines (e.g. Shuttle OMS) and solids experience (e.g. Orion FTS jettison motor) so there are a lot of plausible options.

If that guy's project is official it sounds like Aerojet Rocketdyne is trying to build a future for itself that doesn't rely on ULA. I was going to write that this was surprising back-stabbing of its close business partner ULA but then I remembered that ULA has already cheated on that marriage with their funding of XCOR's RL-10 competitor.

Quote
One other thing: Falcon Heavy is not using cross-feed. They're not developing it. I was at SpaceX several months ago and asked about cross-feed and was told by one of the people working on the rocket that they are not developing it. It's a potential upgrade if somebody pays for it, but they're not doing the development. So you shouldn't use it in your calculations.

Without cross feed Falcon Heavy can send 45 tonnes to LEO according to http://www.spacex.com/falcon-heavy. I suppose that's the best estimate of Falcon Heavy performance to LEO we have currently?

SpaceX's plans for the heaviest payloads involve the BFR so it makes sense that they don't see a need to optimize FH's capacity.
A RL10 upper stage would make all the difference on BLEO missions. It is not just RL10 that makes Centuar expensive but also the design. SpaceX should be able to make a considerable cheaper  equivalent and maybe IVF in the process. At of the technology would be directly applicable to a methane stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/16/2015 08:55 PM
I wrote this in the other thread, but an RL-10 doesn't make sense. In all reality, they probably were just talking about a solid kick stage.

Falcon Heavy even without cross-feed has a LOT of performance. It surely beats both Delta IV Heavy and Atlas 551 to GTO and LEO. But Solar Probe Plus is a VERY high delta-v mission, like C3 = 150+ (km/s)^2. Only New Horizons I think has higher delta-v. So I don't think the idea that SpaceX might want a kick stage for a super-high-delta-v mission necessarily means Falcon Heavy is incapable of any more than one or two missions a decade by itself, and those being NASA missions, not DoD.

And actually, a small kick-stage may be cheaper than expending three cores, so it's even possible they were looking at the kick stage as a way of allowing them to recover the boosters.

So yeah, I'd take Blackstar's rumor with a grain of salt.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/16/2015 08:58 PM
Note that Solar Probe Plus has a launch mass of just 610kg. I believe that's less than the dry mass of the Falcon Heavy upper stage, so it's a good candidate for a small solid kick stage.

It's not about lifting capability, it's about the extremely high energy of the trajectory.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Herb Schaltegger on 02/16/2015 09:03 PM
Bear in mind, too, that in Aerospace-eese, "working on" something can mean anything from one guy running some Excel spreadsheet numbers and ginning up some PowerPoints, to a whole team of designers and mission planners working up a full RFP submittal, to a trucking the finished product out to meet a delivery date.

So I'm sure Blackstar's source told him right, just didn't tell him much at all. ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 02/16/2015 09:07 PM
I wonder if the Aerojet guy that Blackstar ate lunch next to was working on the NASA project to build a common upper stage discussed in this thread: http://forum.nasaspaceflight.com/index.php?topic=35144 . Or maybe this Falcon Heavy upper stage project evolved out of that NASA-funded project?

Bingo, i would put money on that. It is for a kick stage and not a replacement for the existing second stage or an additional liquid stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/16/2015 09:08 PM
An RL-10 upper stage would go completely against SpaceX's demonstrated philosophy of engine and stage commonality.  It would blow launch costs out of the water and create a lot of technical and contractual entanglements that they seem very eager to avoid.

Doesn't mean they won't do it if they have to; just low-probability.  YMMV.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrevorMonty on 02/16/2015 11:08 PM
The engine would be DOD certified if not the stage, one plus going for.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 02/17/2015 12:01 AM
The engine would be DOD certified if not the stage, one plus going for.

That is meaningless.  Components are not certified, only vehicles.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deltaV on 02/17/2015 01:58 AM
Here are some sketchy performance comparisons between no-cross-feed Falcon Heavy (FH) and Delta IV Heavy (DIVH) and Atlas V 551 (AV) for interplanetary trajectories. I'm getting numbers for ULA's launchers from the chart at http://www.nap.edu/openbook.php?record_id=12554&page=109. I'm getting numbers for FH from my rocket equation spreadsheet (a revised version of the one posted at http://forum.nasaspaceflight.com/index.php?topic=33897), which involves lots of numbers pulled out of thin air but is calibrated to match SpaceX's reported 45 tonnes to LEO.

Comparing DIVH to FH it seems FH does better below around C3 = 60 km^2/s^2 (= above 3.5 tonnes payload) and DIVH does better above. Comparing AV to FH it seems FH does better below around C3 = 98 km^2/s^2 (= above 0.8 tonnes payload) and AV does better above. If you give FH a Star 48B kick stage (0.13 tonnes dry, 2.14 tonnes wet, 292.1 s ISP) it outperforms both DIVH and AV to all orbits. Consequently for any possible combination of kick stages for DIVH you can beat it with FH if you add an additional Star 48B to the kick stage collection. Note that FH plus kick stage is probably cheaper than DIVH without a kick stage so giving FH an extra kick stage is not necessarily unfair.

If you give all three launchers a Star 48 then the performance comparison comes down to whether or not the payload plus kick state combined exceed the critical values above, i.e. DIVH does better than FH when payload is less than about 3.5 - 2.14 = 1.36 tonnes, which both launchers can send to around C3 = 131 km^2 / s^2.

Conclusion: even without cross-feed FH does better than DIVH and AV for almost all missions, including LEO, GTO, GEO, Moon and Mars. For the highest delta-vee missions the winner depends on the kick stages used. With no kick stages DIVH beats FH for high C3 missions. With optimal kick stages for each vehicle FH can always throw more, but for the same performance FH may require more complicated kick stage(s) than DIVH.

Concretely:
-Solar Probe Plus is 0.685 tonnes and C3 = 154 km^2/s^2 (http://forum.nasaspaceflight.com/index.php?topic=26605.msg1188790#msg1188790), which is within the capabilities of Star 48B plus either FH or DIVH. The DIVH has slightly better performance here but FH can meet requirements too.
-NASA is considering a Europa mission involving SLS sending about 5 tonnes to C3 = 86 km^2/s^2. As I described elsewhere (http://forum.nasaspaceflight.com/index.php?topic=27871.msg1331978#msg1331978) that's out of reach of FH, DIVH and AV, even with hypergolic or solid kick stages. In theory it's within reach of FH plus a hydrogen kick stage such as Centaur or DCSS, but that's unlikely to be worth the trouble compared to the alternatives of using SLS or a lower energy mission plan with a Venus flyby.

P.S. To sanity-check the above I asked Schillings (http://www.silverbirdastronautics.com/LVperform.html) for FH performance to C3=98 km^2/s^2 and got 2.46 tonnes, substantially more than the 0.8 tonnes I had found. Schillings presumably uses cross-feed; if I turn cross feed on my model increases performance to 1.8 tonnes, a lot closer. My point is this difference between 1.8 tonnes and 2.46 tonnes gives a hint at the magnitude of the error in my figures.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: IainMcClatchie on 02/17/2015 04:03 AM
Hope this is the right thread to post in.

I think I have a scheme which gets the Falcon Heavy most of the benefit of crossfeed with only a small portion of the risk.

At liftoff, five of the core engines slurp the core tanks, and two of the core engines run off each of the booster tanks.  The five core engines throttle down as necessary to limit max Q and max acceleration.  So far, standard crossfeed.

If the center five engines can get down to 50% throttle, the boosters run out of propellant (certainly in the reuse case) before we hit maximum acceleration.  So, the booster engines run at 100% for their whole trip.  When the booster engine cutoff is signaled around +162 seconds, all 22 engines fed by booster tanks cut off.

The four dead engines on the core stage are never restarted.  There is no crossfeed valve.  This is the extent of the idea.  The five remaining engines ramp back up to 100%, and stay at 100% until core engine cutoff at around 310 seconds into flight.

The new hardware needed are new propellant plenums for the core and booster stages, and unions between the adjacent fuel and oxidizer manifolds that can be isolated, drained, and disconnected in flight.

This scheme is not as good as full-blown crossfeed.  It dumps the empty booster weight almost as early as possible.  Perfect crossfeed (100% full core at booster engine cutoff) would dump them 15 seconds earlier, gaining perhaps 60-70 m/s more delta-V.  Perfect crossfeed would also have all nine core engines running after booster separation, which would make the core engine cutoff about 50 seconds earlier, which would reduce gravity losses.  I'm not sure how much delta-V that is worth, perhaps 100 m/s, perhaps more.

This scheme is better than no crossfeed.  Without crossfeed, the booster engine cutoff happens around 200 seconds (assuming reuse).  The extra momentum carried away by the separated boosters costs 160-180 m/s delta-V compared to my scheme.  Also, either the boosters will have to be throttled, or core engines will have to be shut down to avoid overacceleration before booster separation.  The first gets the boosters going even faster when they separate, and the second requires either a midflight restart (with the payload still attached) or delaying core engine cutoff, either of which has penalties.

There is a lot I do not understand on the Falcon Heavy SpaceX page.  It says the core engines throttle down shortly after liftoff (presumably to limit max Q), and throttle up after booster separation.  This implies they stay throttled down between those two events.  It seems to me that once past max Q, I'd want those engines right back up to 100% again to reduce gravity losses.  Maybe they just don't mention those two more throttle moves.

The diagram also shows the boosters about 15% larger than the core stage, the upper stage identical in propellant mass to the F9, and the total liftoff mass 54,702 kg shy of 3x the Falcon 9.  First, why would the FH need a faster liftoff acceleration than the F9?  By loading more propellant, you could get more payload.  Second, I'd expect the booster propellant load to be approximately the same as the F9's first and second stage propellant loads combined, but the increase is only 2/3 of that.  There is plenty of room to stretch those tanks further.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/17/2015 04:13 AM
There is a lot I do not understand on the Falcon Heavy SpaceX page.  It says the core engines throttle down shortly after liftoff (presumably to limit max Q), and throttle up after booster separation.  This implies they stay throttled down between those two events.  It seems to me that once past max Q, I'd want those engines right back up to 100% again to reduce gravity losses.  Maybe they just don't mention those two more throttle moves.

The core is throttled down until separation to leave as much propellant as possible in the core at separation. This improves performance. This is what all 100% liquid heavies do - including Delta IV Heavy and Angara A5.

In the case of FH, it also allows the boosters to stage earlier, so they have an easier time to get back to the launch site.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: IainMcClatchie on 02/17/2015 06:17 AM
The core is throttled down until separation to leave as much propellant as possible in the core at separation. This improves performance.

Right, that's the part I don't understand.

I don't have access to a simulator anymore, but when I used to run simulations, it was always better to burn as much propellant as soon as possible, subject to the limitations of the airframe, and the staging effect.  MaxQ is the first limitation, most rockets have to throttle down a bit to avoid getting too fast in the lower atmosphere.  I know that the Space Shuttle, at least, throttled all the way back up after maxQ.  Typically aero loads have an early maximum just after mach 1, less than 1/3 of the way through the first stage burn, and then trend down from there, as air density drops off faster than velocity^2 increases.  The second limitation is maximum acceleration.  I know the Saturn V and the Falcon 9 both have to throttle down their first stages shortly before engine cutoff to avoid too much acceleration.  But that limitation comes in fairly late in the first stage burn, in the last 20-30 seconds.  Finally, staging helps by eliminating the weight of empty tankage and engines that have had to be turned off.

The longer you wait around to burn off your propellant, the more gravity loss you suffer, especially early in the flight.  This is a strong effect.  There must be some really strong reason to throttle down the core stage on an F9 or D4H launch, to overcome the gravity loss effect.  What is it?

I thought maybe the stress loads on the vehicle would be smaller with less thrust, but upon further thought I think stress loads on the interconnect between the boosters and core are minimized by minimizing the difference between core thrust and booster thrust.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: RonM on 02/17/2015 06:43 AM
The core is throttled down until separation to leave as much propellant as possible in the core at separation. This improves performance.

Right, that's the part I don't understand.

I don't have access to a simulator anymore, but when I used to run simulations, it was always better to burn as much propellant as soon as possible, subject to the limitations of the airframe, and the staging effect.  MaxQ is the first limitation, most rockets have to throttle down a bit to avoid getting too fast in the lower atmosphere.  I know that the Space Shuttle, at least, throttled all the way back up after maxQ.  Typically aero loads have an early maximum just after mach 1, less than 1/3 of the way through the first stage burn, and then trend down from there, as air density drops off faster than velocity^2 increases.  The second limitation is maximum acceleration.  I know the Saturn V and the Falcon 9 both have to throttle down their first stages shortly before engine cutoff to avoid too much acceleration.  But that limitation comes in fairly late in the first stage burn, in the last 20-30 seconds.  Finally, staging helps by eliminating the weight of empty tankage and engines that have had to be turned off.

The longer you wait around to burn off your propellant, the more gravity loss you suffer, especially early in the flight.  This is a strong effect.  There must be some really strong reason to throttle down the core stage on an F9 or D4H launch, to overcome the gravity loss effect.  What is it?

I thought maybe the stress loads on the vehicle would be smaller with less thrust, but upon further thought I think stress loads on the interconnect between the boosters and core are minimized by minimizing the difference between core thrust and booster thrust.

If you go full throttle on the core and the two boosters you are hauling the mass of all three until you run out of propellant. If you throttle back on the core it still has propellant after you dump the mass of the boosters.

You can think of the boosters as the first stage and the core as the second stage. Of course, you have to run the core and the boosters at full throttle to get the thing off the ground.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 02/17/2015 06:45 AM


Schillings presumably uses cross-feed;

Only if you configure the prop load for stages 0 and 1 for "booster and a bit of core prop" and "rest of the core prop", respectively.

Configure differently, and you'll have the non-crossfeed config.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 02/17/2015 08:49 AM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations). Given that limitation and given that I think that Messrs Musk and Bezos would prefer to gouge out their own eyes than work together, the only hydrolox engine likely to be used on Falcon Heavy, IMHO at least (for a certain percentage of 'likely' anyway) is MB-60.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: modemeagle on 02/17/2015 10:41 AM
Hope this is the right thread to post in.

I think I have a scheme which gets the Falcon Heavy most of the benefit of crossfeed with only a small portion of the risk.

At liftoff, five of the core engines slurp the core tanks, and two of the core engines run off each of the booster tanks.  The five core engines throttle down as necessary to limit max Q and max acceleration.  So far, standard crossfeed.

If the center five engines can get down to 50% throttle, the boosters run out of propellant (certainly in the reuse case) before we hit maximum acceleration.  So, the booster engines run at 100% for their whole trip.  When the booster engine cutoff is signaled around +162 seconds, all 22 engines fed by booster tanks cut off.

The four dead engines on the core stage are never restarted.  There is no crossfeed valve.  This is the extent of the idea.  The five remaining engines ramp back up to 100%, and stay at 100% until core engine cutoff at around 310 seconds into flight.

The new hardware needed are new propellant plenums for the core and booster stages, and unions between the adjacent fuel and oxidizer manifolds that can be isolated, drained, and disconnected in flight.

This scheme is not as good as full-blown crossfeed.  It dumps the empty booster weight almost as early as possible.  Perfect crossfeed (100% full core at booster engine cutoff) would dump them 15 seconds earlier, gaining perhaps 60-70 m/s more delta-V.  Perfect crossfeed would also have all nine core engines running after booster separation, which would make the core engine cutoff about 50 seconds earlier, which would reduce gravity losses.  I'm not sure how much delta-V that is worth, perhaps 100 m/s, perhaps more.

This scheme is better than no crossfeed.  Without crossfeed, the booster engine cutoff happens around 200 seconds (assuming reuse).  The extra momentum carried away by the separated boosters costs 160-180 m/s delta-V compared to my scheme.  Also, either the boosters will have to be throttled, or core engines will have to be shut down to avoid overacceleration before booster separation.  The first gets the boosters going even faster when they separate, and the second requires either a midflight restart (with the payload still attached) or delaying core engine cutoff, either of which has penalties.

There is a lot I do not understand on the Falcon Heavy SpaceX page.  It says the core engines throttle down shortly after liftoff (presumably to limit max Q), and throttle up after booster separation.  This implies they stay throttled down between those two events.  It seems to me that once past max Q, I'd want those engines right back up to 100% again to reduce gravity losses.  Maybe they just don't mention those two more throttle moves.

The diagram also shows the boosters about 15% larger than the core stage, the upper stage identical in propellant mass to the F9, and the total liftoff mass 54,702 kg shy of 3x the Falcon 9.  First, why would the FH need a faster liftoff acceleration than the F9?  By loading more propellant, you could get more payload.  Second, I'd expect the booster propellant load to be approximately the same as the F9's first and second stage propellant loads combined, but the increase is only 2/3 of that.  There is plenty of room to stretch those tanks further.

All of my simulations of FH show the maximum payload to orbit was only cross feeding 4 of the 9 engines.  This was simulating the lower performance Merlin 1C before Merlin 1D was created.  The numbers may change now, but I was showing 4 was the best match.  I published a bunch of my simulation runs on earlier Falcon Heavy threads including boost back of the three cores to launch site.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: jak Kennedy on 02/17/2015 11:32 AM
From the Europa science thread Blackstar posted some juicy Falcon Heavy info:

I wonder what sort of fuel that upper stage would use. Aerojet Rocketdyne has a suitable hydrogen engine (RL-10), various hypergolic engines (e.g. Shuttle OMS) and solids experience (e.g. Orion FTS jettison motor) so there are a lot of plausible options.

If that guy's project is official it sounds like Aerojet Rocketdyne is trying to build a future for itself that doesn't rely on ULA. I was going to write that this was surprising back-stabbing of its close business partner ULA but then I remembered that ULA has already cheated on that marriage with their funding of XCOR's RL-10 competitor.
about cross-feed and was told by one of the people working on the rocket that they are not developing it. It's a potential upgrade if somebody pays for it, but they're not doing the development. So you shouldn't use it in your calculations.

If hypergolic's are suitable would/could SpaceX use a kick stage with super dracos?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 02/17/2015 11:41 AM
If hypergolic's are suitable would/could SpaceX use a kick stage with super dracos?

As is, the Super Draco is unsuited for upper atmosphere/vacuum firing. The engine would need an expansion nozzle and maybe some other tweaks. Whilst it might be suitable, it is more likely that, should a payload need a kick stage, SpaceX would require the customer to provide them. Orbital-ATK and AJR make lots of suitable products for that purpose.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: gospacex on 02/17/2015 02:58 PM
Hope this is the right thread to post in.

I think I have a scheme which gets the Falcon Heavy most of the benefit of crossfeed with only a small portion of the risk.

At liftoff, five of the core engines slurp the core tanks, and two of the core engines run off each of the booster tanks.  The five core engines throttle down as necessary to limit max Q and max acceleration.  So far, standard crossfeed.

If the center five engines can get down to 50% throttle, the boosters run out of propellant (certainly in the reuse case) before we hit maximum acceleration.  So, the booster engines run at 100% for their whole trip.  When the booster engine cutoff is signaled around +162 seconds, all 22 engines fed by booster tanks cut off.

The four dead engines on the core stage are never restarted.  There is no crossfeed valve.  This is the extent of the idea.  The five remaining engines ramp back up to 100%, and stay at 100% until core engine cutoff at around 310 seconds into flight.

The new hardware needed are new propellant plenums for the core and booster stages, and unions between the adjacent fuel and oxidizer manifolds that can be isolated, drained, and disconnected in flight.

It looks like you can bite the bullet and just mount those two engines on the boosters instead of the core. Then at booster separation you do not need any disconnects and you are not carrying dead weight on the core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: abaddon on 02/17/2015 03:04 PM
It looks like you can bite the bullet and just mount those two engines on the boosters instead of the core. Then at booster separation you do not need any disconnects and you are not carrying dead weight on the core.

Er... what?  Where exactly are you planning on putting these extra engines?  Even if you could the boosters would then be radically different from the core.  This is a non-starter.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 02/17/2015 04:13 PM
Disconnect can be with quick disconnect type couplings.  The Soyuz rocket uses cross feed and has since the 1950's.  They just send a signal and they disconnect.  Very few failures if any.  I'm surprised Delta IV heavy hasn't used cross feed to get another 5-10 tons or so to orbit.  I think the original Falcon Heavy 53 tons to LEO was with cross feed.  I think it is 45 or so without.  Someone can chime in here with exacts.  Cross feed doesn't have to go straight to the engines, it can go to the fuel and oxidizer tanks on the boosters to the core.  That way there is only 4 connections to disconnect.   
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/17/2015 04:14 PM
The Soyuz rocket uses cross feed and has since the 1950's.  They just send a signal and they disconnect.

Huh? Since when?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 02/17/2015 04:23 PM
I read somewhere that the 4 strap ons burn with the core and transfer fuel to the core at the same time.  Then they drop off and the core continues.  Maybe they don't since they are smaller.  However I read that years ago. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/17/2015 04:27 PM
I read somewhere that the 4 strap ons burn with the core and transfer fuel to the core at the same time.  Then they drop off and the core continues.  Maybe they don't since they are smaller.  However I read that years ago.

That is incorrect. There is no propellant transfer. The boosters just jettison when they are empty, and the core (called stage 2) just burns longer because it has larger tanks.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrueBlueWitt on 02/17/2015 04:29 PM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations). Given that limitation and given that I think that Messrs Musk and Bezos would prefer to gouge out their own eyes than work together, the only hydrolox engine likely to be used on Falcon Heavy, IMHO at least (for a certain percentage of 'likely' anyway) is MB-60.

They have a long fairing.. Would s  Centaur fit in the fairing with s high C3 Sat? RL-10 powered S3 would have plenty of thrust. S2 did the heavy lifting in earth's gravity.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Nate_Trost on 02/17/2015 04:29 PM
There is a simple question and simple answer in regards to Falcon Heavy cross-feed development.

Q: Why would SpaceX develop cross-feed for Falcon Heavy?
A: Because it is necessary to meet sufficient demand for customer payload requirements.

It isn't going to happen just because. It would happen because it was necessary for enough paying customers that would justify the development cost, or a customer needed it badly enough to pay for it. And it isn't really clear that that is something that is going to happen in the next 15 years. SpaceX themselves won't need it: their long-term Mars plans revolve around BFR. Any reusable SpaceX BFR in 10-15 years would make a cross-feed FH obsolete.

So who is the customer? And don't say Bigelow. At this point, it seems a rather long shot that he ever pulls together several hundred million dollars to develop, build and fly even one of the smaller modules, much less a larger one. And, again, if you're the *only* customer for a cross-feed Falcon Heavy, guess who gets to foot the tab for development?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 02/17/2015 05:09 PM
Hopefully this is the right thread for this question.

Has SpaceX said anything for sure about if they plan to upgrade LC-40 to handle FH?

I'd assume they would, perhaps after 39A is up and fully functional becuase an upgrade to LC-40 like that will mean it'll be out of commission for awhile, and their manifest is packed right now.

But I don't recall anything for sure about it, other than an old comment by Elon saying they might build a FH HIB at a 90 degree angle to the F9 HIB.  I think that was before 39A was in the mix, so they could keep flying F9 while upgrading to FH.  With 39A operational, I think they can just fly from there and tear down the F9 HIB and build the FH HIB there

Or will they just leave LC-40 launching F9 only?

They have mentioned doing it, but plans change, and most of those comments were pre-39A acquisition. Now that they have 39A I don't see them being in a hurry do it. Perhaps never. But it also depends on two additional factors:
 - What will be the ratio of F9 to FH launches going forward?
 - How quickly will the Texas launch pad come online (presumably built to support FH from the beginning)

Agreed, I was just wondering if there was any more recent information out there about their plans.

Myself, I'd think they will upgrade it, for the added flexibility of having the ability to launch FH from there.  But it'd probably wait until after a Boca Chica pad were operational and they had the launch capacity to take LC-40 off line for awhile. 

One question, -could- they rebuild the existing HIB to accomodate FH?  Given the location of the flame duct?  It's located to the side of the pad, rather than in "front" like SLC-4E, LC-39A, and Boca Chica's concept art.  That means the far side booster's exhaust would have to cut accross the central and duct-side booster.  Would that be an issue?  Looks like Titan was arranged at 90 degrees to how FH would be, with each booster discharging directly out the "front" so there's no crossing of exhaust.  Looks like LC-41 with Titan was like that too in the pic below, as well as SLC-4E.  The Titan MSS's on all of those retracted to the side.  SpaceX used the  Titan MSS rails to transport F9 on LC-40 so it came from the side, rather than from the "back" like SLC-4E.  Ok for a single core LV, but for a tri-core?   I figured it would be so there'd be shorter inturruption to pad operations, but that might be the way FH would have to sit on the pad.  It'll probably mean the existing HIB is torn down as I don't know if they can make a pad accessable from two directions.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MTURN91750 on 02/17/2015 06:02 PM
There is a simple question and simple answer in regards to Falcon Heavy cross-feed development.

Q: Why would SpaceX develop cross-feed for Falcon Heavy?
A: Because it is necessary to meet sufficient demand for customer payload requirements.

It isn't going to happen just because. It would happen because it was necessary for enough paying customers that would justify the development cost, or a customer needed it badly enough to pay for it. And it isn't really clear that that is something that is going to happen in the next 15 years. SpaceX themselves won't need it: their long-term Mars plans revolve around BFR. Any reusable SpaceX BFR in 10-15 years would make a cross-feed FH obsolete.

So who is the customer? And don't say Bigelow. At this point, it seems a rather long shot that he ever pulls together several hundred million dollars to develop, build and fly even one of the smaller modules, much less a larger one. And, again, if you're the *only* customer for a cross-feed Falcon Heavy, guess who gets to foot the tab for development?

I think with any other launch vehicle company you're right, but SpaceX's goals are different. Even on SpaceX's website they mention using the Falcon Heavy to take crews to Mars so getting as much performance out of FH seems logical. Bigelow might be a good way to pay for some the development. That extra performance also might help in development with the MCT. I always thought that the MCT and BFR were going to be developed in parallel so I could see how a better performing Falcon Heavy might be useful to test MCT technology before the BFR is ready. Just saying it won't be developed because today's customers don't have a need for it seems like a very simplistic view of SpaceX's goals and business model.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/17/2015 06:06 PM
The multi-core BFR posts are out of date. Musk has made fairly clear recently (in the MIT talk, I believe?) that the BFR will be single-core (though they were looking at multi-core before), I think due to operational reasons.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco on 02/17/2015 06:53 PM
1 - Could the M1D thrust upgrade and prop densification fully compensate no cross feed ?
2 - Just because SpaceX mentioned a few times flying people to Mars on Falcon Heavy doesn't mean it's still in the cards. SpaceX has shown multiple times the ability to evolve its plans. Don't get hung up on words from many years ago if they don't get reinforced (with more words or actions).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/17/2015 07:00 PM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations). Given that limitation and given that I think that Messrs Musk and Bezos would prefer to gouge out their own eyes than work together, the only hydrolox engine likely to be used on Falcon Heavy, IMHO at least (for a certain percentage of 'likely' anyway) is MB-60.

Are there any known plans to install (or use existing) LH2 infrastructure at SLC-4E or 39A?  I just don't see SpaceX dealing with LH2 at all.  LH2 is extremely high cost, high maintenance technology that limits materials, design and processes not just on the rocket but on the pad.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 02/17/2015 07:01 PM
Seems like throttling down the core while throttling up the boosters works ok. 

However, they could have cross feed with the kerosene only, by having the core built with a small kerosene tank and larger oxygen tank while the boosters could have smaller oxygen tanks and larger kerosene tanks.  That way only the kerosene is cross fed using easier more traditional equipment to disconnect. 

They could also stretch the core while shortening the boosters so they drop off earlier.  Seems like no matter what they do, the most cost effective will be there option.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MTURN91750 on 02/17/2015 07:26 PM
1 - Could the M1D thrust upgrade and prop densification fully compensate no cross feed ?
2 - Just because SpaceX mentioned a few times flying people to Mars on Falcon Heavy doesn't mean it's still in the cards. SpaceX has shown multiple times the ability to evolve its plans. Don't get hung up on words from many years ago if they don't get reinforced (with more words or actions).

You can go to SpaceX's website right now and find this exact quote under Falcon Heavy:

Quote
http://www.spacex.com/falcon-heavy: Falcon Heavy was designed from the outset to carry humans into space and restores the possibility of flying missions with crew to the Moon or Mars.

I'm not getting hung up on anything. I'm just pointing out something that's on SpaceX's website TODAY mentions using the Falcon Heavy for Mars.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AncientU on 02/17/2015 07:32 PM
There is a simple question and simple answer in regards to Falcon Heavy cross-feed development.

Q: Why would SpaceX develop cross-feed for Falcon Heavy?
A: Because it is necessary to meet sufficient demand for customer payload requirements.

It isn't going to happen just because. It would happen because it was necessary for enough paying customers that would justify the development cost, or a customer needed it badly enough to pay for it. And it isn't really clear that that is something that is going to happen in the next 15 years. SpaceX themselves won't need it: their long-term Mars plans revolve around BFR. Any reusable SpaceX BFR in 10-15 years would make a cross-feed FH obsolete.

So who is the customer? And don't say Bigelow. At this point, it seems a rather long shot that he ever pulls together several hundred million dollars to develop, build and fly even one of the smaller modules, much less a larger one. And, again, if you're the *only* customer for a cross-feed Falcon Heavy, guess who gets to foot the tab for development?
When will people stop thinking/stating with certainty that anything is CLEAR in the future, especially 10-15 years hence?  In the year 2000, would you or anyone have been certain that we'd be where we are in space launch business in 2015? 

Stop, please. (You don't have a clue. None of us has a clue.)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MTURN91750 on 02/17/2015 07:43 PM
The multi-core BFR posts are out of date. Musk has made fairly clear recently (in the MIT talk, I believe?) that the BFR will be single-core (though they were looking at multi-core before), I think due to operational reasons.

Point taken. I'll modify my post.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dror on 02/17/2015 08:14 PM
The multi-core BFR posts are out of date. Musk has made fairly clear recently (in the MIT talk, I believe?) that the BFR will be single-core (though they were looking at multi-core before), I think due to operational reasons.


It was at the reddit AMA :

Quote from: https://www.reddit.com/r/IAmA/comments/2rgsan/i_am_elon_musk_ceocto_of_a_rocket_company_ama/cnfpn7r
[–]FoxhoundBat 12 points 20 minutes ago
In order to use the full MCT design (100 passengers), will BFR be one core or 3 cores?

[–]ElonMuskOfficial 6 points a minute ago
At first, I was thinking we would just scale up Falcon Heavy, but it looks like it probably makes more sense just to have a single monster boost stage.

" but it looks like it probably makes more sense "
Hardly conclusive. I wouldnt dissmiss the tri core concept altogether based on a triple disclaimed sentence.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: mfck on 02/17/2015 08:46 PM
The multi-core BFR posts are out of date. Musk has made fairly clear recently (in the MIT talk, I believe?) that the BFR will be single-core (though they were looking at multi-core before), I think due to operational reasons.


It was at the reddit AMA :

Quote from: https://www.reddit.com/r/IAmA/comments/2rgsan/i_am_elon_musk_ceocto_of_a_rocket_company_ama/cnfpn7r
[–]FoxhoundBat 12 points 20 minutes ago
In order to use the full MCT design (100 passengers), will BFR be one core or 3 cores?

[–]ElonMuskOfficial 6 points a minute ago
At first, I was thinking we would just scale up Falcon Heavy, but it looks like it probably makes more sense just to have a single monster boost stage.

" but it looks like it probably makes more sense "
Hardly conclusive. I wouldnt dissmiss the tri core concept altogether based on a triple disclaimed sentence.
Well, it's a 3-sigma statement...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 02/17/2015 08:47 PM
I could see some use in Falcon heavy for Mars, but as a ferry to an L1 or L2 assembly area using Dragon as a taxi to ferry astronauts or colonists.  Also to ferry some smaller items, supplies, or even some fuel, but a big rocket would still be needed for the larger items needed. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/17/2015 10:46 PM
When will people stop thinking/stating with certainty that anything is CLEAR in the future, especially 10-15 years hence?  In the year 2000, would you or anyone have been certain that we'd be where we are in space launch business in 2015? 

Stop, please. (You don't have a clue. None of us has a clue.)

Interesting you should say that.  I'm re-reading "To Reach the High Frontier: A History of U.S. Launch Vehicles" edited by Roger Launius, published in 2002 but with material no later than 2001 at the latest.  There is no mention of SpaceX at all.  Atlas 5 and Delta 4 were still in the works.  A very different time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MTURN91750 on 02/17/2015 11:00 PM
Has anybody seen any recent information on whether or not SpaceX will develop a larger fairing for FH? This to me seems like another item that would only be paid for if a customer wants it, but it also seems like a much cheaper upgrade than cross-feeding.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AncientU on 02/18/2015 12:05 AM
Has anybody seen any recent information on whether or not SpaceX will develop a larger fairing for FH? This to me seems like another item that would only be paid for if a customer wants it, but it also seems like a much cheaper upgrade than cross-feeding.
I requested just that information from SpaceX a while back... for a project I'm working.
No answer received.  Must be time to ask again.

There is certainly room to go longer, to 18m range mentioned up thread, and/or wider to around 6m.
At 45-50 mT to LEO/20ish to GTO, they will be severely volume limited with present fairing.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: IainMcClatchie on 02/18/2015 12:08 AM
If you go full throttle on the core and the two boosters you are hauling the mass of all three until you run out of propellant. If you throttle back on the core it still has propellant after you dump the mass of the boosters.

Thank you.  Dumping the boosters at lower speed would have a large effect.  That's what I was looking for.

I thought of perhaps another way to do full cross-feed without affecting the bottom of the rocket at all.  The boosters are taller than the core stage.  You could arrange for each booster to have two LOX tanks and two kerosene tanks, one set half the size of the other.  The smaller kerosene tank sits above the main kerosene tank, and significantly, the bottom of the smaller booster kerosene tank sits above the top of the core kerosene tank.  It drains into the core kerosene tank by gravity feed.  Similarly, the bottom of the smaller booster LOX tank sits above the top of the core LOX tank, and drains by gravity feed as well.  Note that gravity feed is fairly powerful, as the accelerations before booster burnout are over 3G.

This scheme is perfect cross-feed, but with the added weight of two more tank bulkheads and the cross piping and unions.  No special lines are needed to blow the cross piping clear of propellant before closing the valves and disconnecting.  The pressurization system of the booster propellant tank can positively drain all the fluid into the core tanks before separation.

Given that at separation you'd have nearly full core tanks, the propellant burn before separation is always the same and any throttling down just postpones the booster separation and increases gravity losses.  Once past max Q you'd ramp all the engines to 100% and leave them there through booster ECO at around 155 seconds.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 02/18/2015 12:27 AM

I thought of perhaps another way to do full cross-feed without affecting the bottom of the rocket at all.  The boosters are taller than the core stage.  You could arrange for each booster to have two LOX tanks and two kerosene tanks, one set half the size of the other.  The smaller kerosene tank sits above the main kerosene tank, and significantly, the bottom of the smaller booster kerosene tank sits above the top of the core kerosene tank.  It drains into the core kerosene tank by gravity feed.  Similarly, the bottom of the smaller booster LOX tank sits above the top of the core LOX tank, and drains by gravity feed as well.  Note that gravity feed is fairly powerful, as the accelerations before booster burnout are over 3G.

This scheme is perfect cross-feed, but with the added weight of two more tank bulkheads and the cross piping and unions.  No special lines are needed to blow the cross piping clear of propellant before closing the valves and disconnecting.  The pressurization system of the booster propellant tank can positively drain all the fluid into the core tanks before separation.

Given that at separation you'd have nearly full core tanks, the propellant burn before separation is always the same and any throttling down just postpones the booster separation and increases gravity losses.  Once past max Q you'd ramp all the engines to 100% and leave them there through booster ECO at around 155 seconds.

that doesn't make any sense.  The few feet of head pressure is not going to matter and it is a waste to have separate tanks

also, there is no need to blow the lines clear before closing valves.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 02/18/2015 12:33 AM

The longer you wait around to burn off your propellant, the more gravity loss you suffer, especially early in the flight.  This is a strong effect.  There must be some really strong reason to throttle down the core stage on an F9 or D4H launch, to overcome the gravity loss effect.  What is it?

I thought maybe the stress loads on the vehicle would be smaller with less thrust, but upon further thought I think stress loads on the interconnect between the boosters and core are minimized by minimizing the difference between core thrust and booster thrust.

Because it makes the core a second stage. It does no good to have triple the thrust and propellant on the first stage and still have the same upper stage.  The throttle down of the core and its ability to burn longer make the Heavy have essentially 3 stages.

The stress loads on the interconnects don't need to be minimized.  The boosters are lifting the core much like the SRMs on Titan III and IV.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deltaV on 02/18/2015 04:35 AM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations).

If someone wanted to replace Falcon Heavy's upper stage with a hydrogen stage it would be reasonable to use a cluster of several RL-10s to get enough thrust (similar to DIRECT and ACES plans) so you can't rule out RL-10 for thrust reasons. Also IMHO a more likely (but still unlikely) use of hydrogen with Falcon Heavy would be use of an existing ULA RL-10-based stage (i.e. DCSS or Centaur) as an in-space kick stage on top of the existing Falcon upper stage (not a replacement), a task for which a single RL-10 is the right size.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 02/18/2015 05:19 AM



I thought of perhaps another way to do full cross-feed without affecting the bottom of the rocket at all.  The boosters are taller than the core stage.  You could arrange for each booster to have two LOX tanks and two kerosene tanks, one set half the size of the other.  The smaller kerosene tank sits above the main kerosene tank, and significantly, the bottom of the smaller booster kerosene tank sits above the top of the core kerosene tank.  It drains into the core kerosene tank by gravity feed.  Similarly, the bottom of the smaller booster LOX tank sits above the top of the core LOX tank, and drains by gravity feed as well.  Note that gravity feed is fairly powerful, as the accelerations before booster burnout are over 3G.

This scheme is perfect cross-feed, but with the added weight of two more tank bulkheads and the cross piping and unions.  No special lines are needed to blow the cross piping clear of propellant before closing the valves and disconnecting.  The pressurization system of the booster propellant tank can positively drain all the fluid into the core tanks before separation.

Given that at separation you'd have nearly full core tanks, the propellant burn before separation is always the same and any throttling down just postpones the booster separation and increases gravity losses.  Once past max Q you'd ramp all the engines to 100% and leave them there through booster ECO at around 155 seconds.

that doesn't make any sense.  The few feet of head pressure is not going to matter and it is a waste to have separate tanks

also, there is no need to blow the lines clear before closing valves.

I think you're missing that this is proposing to drain into the top of the core tanks, and "positive drain" is re no residuals in those tanks at separation.

"Head pressure" assumes connection at the stage base, I believe? This is the plan, of course.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: ChrisWilson68 on 02/18/2015 06:06 AM
There is a simple question and simple answer in regards to Falcon Heavy cross-feed development.

Q: Why would SpaceX develop cross-feed for Falcon Heavy?
A: Because it is necessary to meet sufficient demand for customer payload requirements.

It isn't going to happen just because. It would happen because it was necessary for enough paying customers that would justify the development cost, or a customer needed it badly enough to pay for it. And it isn't really clear that that is something that is going to happen in the next 15 years. SpaceX themselves won't need it: their long-term Mars plans revolve around BFR. Any reusable SpaceX BFR in 10-15 years would make a cross-feed FH obsolete.

So who is the customer? And don't say Bigelow. At this point, it seems a rather long shot that he ever pulls together several hundred million dollars to develop, build and fly even one of the smaller modules, much less a larger one. And, again, if you're the *only* customer for a cross-feed Falcon Heavy, guess who gets to foot the tab for development?
When will people stop thinking/stating with certainty that anything is CLEAR in the future, especially 10-15 years hence?  In the year 2000, would you or anyone have been certain that we'd be where we are in space launch business in 2015? 

Stop, please. (You don't have a clue. None of us has a clue.)

Why are you picking on Nate_Trost's post for this?  It doesn't claim anything is clear -- on the contrary, it says "it isn't really clear".
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: hkultala on 02/18/2015 06:29 AM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations).

If someone wanted to replace Falcon Heavy's upper stage with a hydrogen stage it would be reasonable to use a cluster of several RL-10s to get enough thrust (similar to DIRECT and ACES plans) so you can't rule out RL-10 for thrust reasons. Also IMHO a more likely (but still unlikely) use of hydrogen with Falcon Heavy would be use of an existing ULA RL-10-based stage (i.e. DCSS or Centaur) as an in-space kick stage on top of the existing Falcon upper stage (not a replacement), a task for which a single RL-10 is the right size.

You cannot fit enough RL-10's inside the diameter of a falcon stage. Propably 2 is the maximum number that would fit, and even those would have to be old A-series models. And that 2 engines would mean upper stage thrust of about 1/3 of the current upper stage thrust, which would very propably mean worse performance than with current merlin engine.

2 MB-60's might give enough thrust to give increase in payload, but how wide are those?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 02/18/2015 10:43 AM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations). Given that limitation and given that I think that Messrs Musk and Bezos would prefer to gouge out their own eyes than work together, the only hydrolox engine likely to be used on Falcon Heavy, IMHO at least (for a certain percentage of 'likely' anyway) is MB-60.

Are there any known plans to install (or use existing) LH2 infrastructure at SLC-4E or 39A?  I just don't see SpaceX dealing with LH2 at all.  LH2 is extremely high cost, high maintenance technology that limits materials, design and processes not just on the rocket but on the pad.

Just to clarify, I don't see SpaceX working towards a high-energy chemical upper stage any time soon. Methalox is fine for their next-gen propulsion development, which will be okay up to cis-lunar. Further than that, I suspect that MCT will be solar-electric or something else even more exotic that Dr Evil Elon is hiding up his sleeve. All I was saying is that, with BE-3 ruled out for personality clash reasons, MB-60 is the only hydrolox engine suitably sized for an alternate high-energy upper stage for Falcon Heavy, IMHO at least. An RL-10C cluster would probably be slightly outside what could be fit into the interstage
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AncientU on 02/18/2015 12:30 PM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations). Given that limitation and given that I think that Messrs Musk and Bezos would prefer to gouge out their own eyes than work together, the only hydrolox engine likely to be used on Falcon Heavy, IMHO at least (for a certain percentage of 'likely' anyway) is MB-60.

Are there any known plans to install (or use existing) LH2 infrastructure at SLC-4E or 39A?  I just don't see SpaceX dealing with LH2 at all.  LH2 is extremely high cost, high maintenance technology that limits materials, design and processes not just on the rocket but on the pad.

Just to clarify, I don't see SpaceX working towards a high-energy chemical upper stage any time soon. Methalox is fine for their next-gen propulsion development, which will be okay up to cis-lunar. Further than that, I suspect that MCT will be solar-electric or something else even more exotic that Dr Evil Elon is hiding up his sleeve. All I was saying is that, with BE-3 ruled out for personality clash reasons, MB-60 is the only hydrolox engine suitably sized for an alternate high-energy upper stage for Falcon Heavy, IMHO at least. An RL-10C cluster would probably be slightly outside what could be fit into the interstage

There are no laws of physics violated by using methlox to travel beyond cis-lunar. Hydrolox has advantages and disadvantages, especially for long duration flights that need to carry fuel for propulsive EDL. SpaceX is on record favoring(possibly to the exclusion of other fuels) methlox and are building engines for that fuel. The RL-10 is an expensive engine and not proven for reuse as far as I know. Cannot see any reason for FH upgrade with external supplied engine or use of fuel that has been specifically passed over in favor of methlox.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: inventodoc on 02/18/2015 01:25 PM
Regarding the possibility of an RL-10 based upper stage..... I think an RL10 engine is in the price range or above the price of an entire F9 upper stage.  Delta IV economics won't fly on a SpaceX rocket.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrueBlueWitt on 02/18/2015 01:52 PM
Regarding the possibility of an RL-10 based upper stage..... I think an RL10 engine is in the price range or above the price of an entire F9 upper stage.  Delta IV economics won't fly on a SpaceX rocket.

A low thrust Rl-10 or otherwise high ISP kick stage should fit in F9 fairing with a BEO payload. This could be a good combination for europa mission with better performance than DIVH still at far lower price.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: ArbitraryConstant on 02/18/2015 02:13 PM
I wrote this in the other thread, but an RL-10 doesn't make sense. In all reality, they probably were just talking about a solid kick stage.
++

Only New Horizons I think has higher delta-v.
I believe this mission also used a solid motor kick stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/18/2015 02:56 PM
Regarding the possibility of an RL-10 based upper stage..... I think an RL10 engine is in the price range or above the price of an entire F9 upper stage.  Delta IV economics won't fly on a SpaceX rocket.

A low thrust Rl-10 or otherwise high ISP kick stage should fit in F9 fairing with a BEO payload. This could be a good combination for europa mission with better performance than DIVH still at far lower price.
Doesn't need to be a particularly high Isp kick stage if the probe is small. Just a typical small solid rocket motor with a vacuum-optimized nozzle.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: notsorandom on 02/18/2015 03:31 PM
As others have already pointed out, the info Blackstar related is most likely referring to a solid kick stage. Just like the Star 48 used with the New Horizons mission. Solar Probe Plus certainly doesn't have the budget to design, certify, and build a new high energy liquid kick stage. Solar Probe Plus is only one mission. The number of payloads which need such a high C3 are few and far between. New Horizons was the last one which was in that escape velocity range. It dosn't make sense for SpaceX to redesign their rocket to accommodate an LH2 stage just to potentially launch one payload a decade. They already will have plenty of performance in the Falcon Heavy to cover the market.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/18/2015 03:58 PM
Maybe we should stop trying to pack all the energy for any given mission into a single launch. 

1. Assuming SpaceX can recover and reuse all three cores several times, the cost of each flight should come way, way down.  IMHO this is the BIG factor that opens up multiple-launch missions.

2. SpaceX, with NASA, is already extremely competent in LEO rendezvous and multi-spacecraft operations.  Berthing is done, docking will be accomplished within a year or two.

3. There will soon be multiple FH pads for eastward trajectories.  Meaning very small delays between, say, two FH launches intended to hook up rapidly in orbit.

So, SpaceX may see absolutely no need to hog-tie itself with its own, or worse, someone else's high-energy upper stage.  They could, for example, fly the primary payload with the usual upper stage depleted to the usual residuals.  They could then fly a second upper stage with much greater residuals because the only payload would be its half of a docking system.  Together, two stages provide the services of escape and kick.

Another example: the second flight installs ion propulsion on the first stack.  The original US does escape, and the ion engine does the rest.

Just ideas.  Sorry if I've pegged someone's nonsense meter!   ;D

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 02/18/2015 04:54 PM
Punder the main issue with that is not the docking but expecting the Lox not to evaporate too quickly in whatever upper stage(s) it is in. This means both US need at least very efficient passive cooling including attitude control to keep the craft oriented so it radiates heat away from any radiative heat source and has radiative shielding  that stays in between it and the major radiative heat sources (Earth, Sun, Moon). This may be a little complex considering they will be docking/birthing nose to nose.

A much smaller side issue is that you will need to dock the two craft top to top which introduces complexity to the final payload needing a frame around it with a docking port, the eventual ejection of that frame and being able to sustain negative g's in the case of the dual KeroLox US propulsion. 

Given that we are using the existing US, we have to also be concerned of the stresses on the docking connection. For the dual KeroLox version I suggest the least troublesome arrangement would be a bolting connection like the birthing adaptor AND that release from the  payload and it's original US by the 2nd upper stage take place from the frame that distributes the pressure from the 2nd upper stages thrusting so that you are left after the 2nd upper stage separates with just the original upper stage, the final craft and whatever adapting connector you have between them.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: docmordrid on 02/18/2015 05:22 PM
As others have already pointed out, the info Blackstar related is most likely referring to a solid kick stage. Just like the Star 48 used with the New Horizons mission. Solar Probe Plus certainly doesn't have the budget to design, certify, and build a new high energy liquid kick stage.
>

OTOH, could this tie into the NASA common upper stage discussed at the link, which apparently (according to SN) used F9 as a reference vehicle?

Link.... (http://spacenews.com/37757nasa-mulls-common-upper-stage-for-launch-services-catalog/)

Quote
>
......, Aerojet and Orbital were asked to design a reference mission for NASA that shows how quickly the companies’ chosen upper stages — whatever those may be — could propel a payload beyond Earth assuming launch by a rocket approximately as powerful as Space Exploration Technologies Corp.’s (SpaceX) Falcon 9 v1.1.
>
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/18/2015 06:01 PM
Punder the main issue with that is not the docking but expecting the Lox not to evaporate too quickly in whatever upper stage(s) it is in. This means both US need at least very efficient passive cooling including attitude control to keep the craft oriented so it radiates heat away from any radiative heat source and has radiative shielding  that stays in between it and the major radiative heat sources (Earth, Sun, Moon). This may be a little complex considering they will be docking/birthing nose to nose.

A much smaller side issue is that you will need to dock the two craft top to top which introduces complexity to the final payload needing a frame around it with a docking port, the eventual ejection of that frame and being able to sustain negative g's in the case of the dual KeroLox US propulsion. 

Given that we are using the existing US, we have to also be concerned of the stresses on the docking connection. For the dual KeroLox version I suggest the least troublesome arrangement would be a bolting connection like the birthing adaptor AND that release from the  payload and it's original US by the 2nd upper stage take place from the frame that distributes the pressure from the 2nd upper stages thrusting so that you are left after the 2nd upper stage separates with just the original upper stage, the final craft and whatever adapting connector you have between them.

Cryo boiloff is why I suggested launches in quick succession, as close to one orbit as possible.  First flight from Texas, second from Florida or vice versa.  SIIC and SIVB survived this sort of timeframe, as does the Centaur as far as I know.

(In fact, now that I think about it... launch from Texas first.  Launch from Florida as Tex goes blasting by.  The flights would be many miles apart at first, but with trajectories designed to converge with minimal deltaV at some point later on.)

Just a thought to avoid nose-to-nose docking.  Use the 1st flight US engine bell as the drogue in a probe-and-drogue system.  The probe is a lightweight, perhaps inflatable device that may or may not impart some of the loads into the engine bell from the 2nd flight US thrust.  The main thrust structure is two mating rings around the periphery of the 1st flight US bottom and the 2nd flight US top.  (Envision the bridge lattice structure between the Soyuz center core and 2nd stage.)  The usual capture screw arrangement and an electrical umbilical connection.

Look, I'm not a mechanical engineer, and I perfectly realize there are many factors here of which I'm ignorant.  There will have to be precise RCS, detection circuitry, orbital analysis, boiloff reserves, and on and on.  I personally just can't think of any showstopper, or really any vastly difficult/expensive problem, that blows this idea away.  In fact virtually all of it has been done before, other than the engine bell probe-and-drogue.  And on that subject... Isn't the engine bell of a rocket the PERFECT place to direct some force?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/18/2015 06:13 PM
Look, I'm not a mechanical engineer, and I perfectly realize there are many factors here of which I'm ignorant.  There will have to be precise RCS, detection circuitry, orbital analysis, boiloff reserves, and on and on.  I personally just can't think of any showstopper, or really any vastly difficult/expensive problem, that blows this idea away.  In fact virtually all of it has been done before, other than the engine bell probe-and-drogue.  And on that subject... Isn't the engine bell of a rocket the PERFECT place to direct some force?

NO. :) The nozzle edges are usually very thin and fragile. At least for upper stage engines with nozzle extensions.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/18/2015 06:38 PM
Look, I'm not a mechanical engineer, and I perfectly realize there are many factors here of which I'm ignorant.  There will have to be precise RCS, detection circuitry, orbital analysis, boiloff reserves, and on and on.  I personally just can't think of any showstopper, or really any vastly difficult/expensive problem, that blows this idea away.  In fact virtually all of it has been done before, other than the engine bell probe-and-drogue.  And on that subject... Isn't the engine bell of a rocket the PERFECT place to direct some force?

NO. :) The nozzle edges are usually very thin and fragile. At least for upper stage engines with nozzle extensions.

Okay, so forget that part.  (And I do appreciate the smiley.)  Use the ring trusses as the sole thrust structure and align/dock the stages some other way.  Anything else in the "big concept" that's utterly nonsensical?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 02/18/2015 06:40 PM
Purely FWIW, I think that RL-10C's thrust is too low for use on Falcon Heavy, even if you use cross-feed on the core and boosters. Staging is just too low and slow (because of RTLS performance limitations). Given that limitation and given that I think that Messrs Musk and Bezos would prefer to gouge out their own eyes than work together, the only hydrolox engine likely to be used on Falcon Heavy, IMHO at least (for a certain percentage of 'likely' anyway) is MB-60.

Are there any known plans to install (or use existing) LH2 infrastructure at SLC-4E or 39A?  I just don't see SpaceX dealing with LH2 at all.  LH2 is extremely high cost, high maintenance technology that limits materials, design and processes not just on the rocket but on the pad.

Just to clarify, I don't see SpaceX working towards a high-energy chemical upper stage any time soon. Methalox is fine for their next-gen propulsion development, which will be okay up to cis-lunar. Further than that, I suspect that MCT will be solar-electric or something else even more exotic that Dr Evil Elon is hiding up his sleeve. All I was saying is that, with BE-3 ruled out for personality clash reasons, MB-60 is the only hydrolox engine suitably sized for an alternate high-energy upper stage for Falcon Heavy, IMHO at least. An RL-10C cluster would probably be slightly outside what could be fit into the interstage

Yup.  Probably just a low cost solid kick stage to make up a performance gap for some payloads, expanding what Falcon can do overall.  After taking a look at hydrolox for the original "Raptor", it seems they've ran screaming away from it given it's problematic nature. 
FH has a ton of lifting performance, so while putting a heavy solid kick stage on isn't the most efficient, it has lifting capacity to spare to do it and it would likely cost a whole lot less than a hydrolox stage in both development and infrastructure upgrades.
Aerojet is one of the two solid motor manufacturers in the US so it makes a lot of sense for a guy from Aerojet to be working on a solid kick stage. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 02/18/2015 07:07 PM


Okay, so forget that part.  (And I do appreciate the smiley.)  Use the ring trusses as the sole thrust structure and align/dock the stages some other way.  Anything else in the "big concept" that's utterly nonsensical?

Back to the boil off issue, if you are only looking for a single impulse from the two stages then, as long as you dock them and get that impulse in the first orbit you should not have lost too much. However, if one of the reasons you wanted all this extra capacity for a probe included a high energy orbit change later on then you still need to solve the boil off (and operation power issues since the main solar panels won't be deployed until after the last high energy burn). 

I am not seeing how this gets you a solution that is cheaper than 3'rd stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/18/2015 07:25 PM


Okay, so forget that part.  (And I do appreciate the smiley.)  Use the ring trusses as the sole thrust structure and align/dock the stages some other way.  Anything else in the "big concept" that's utterly nonsensical?

Back to the boil off issue, if you are only looking for a single impulse from the two stages then, as long as you dock them and get that impulse in the first orbit you should not have lost too much. However, if one of the reasons you wanted all this extra capacity for a probe included a high energy orbit change later on then you still need to solve the boil off (and operation power issues since the main solar panels won't be deployed until after the last high energy burn). 

I am not seeing how this gets you a solution that is cheaper than 3'rd stage.

There may not be a solution.  This is what you guys call "hand-waving" after all!  But:

1.  The 2nd flight US has a bunch of propellant.  It had no payload, after all, other than the weight of the docking mechanism and any rendezvous sensors/computers.  Maybe it only had a small expendable nosecone rather than a big heavy payload shroud.  Seems like that would make for much larger payload than a 3rd stage added to a single launch.

2.  Common stages, common engines, common propellants, common software, common power, common procedures, common personnel.  All from within SpaceX.  No additional companies, personnel, procedures, safety concerns, or pad mods for a non-common stage.  Each interaction between dissimilar items eats money and poops paper + lost time.

3.  The state of the art wrt cryo boiloff may improve.  People have been working on depot tech for awhile now.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/18/2015 07:30 PM
Maybe we should stop trying to pack all the energy for any given mission into a single launch.  ...
For anything like this, multiple launches don't make any sense.

I'm not sure of the exact figures, but I'm pretty sure a small solid rocket kick motor is in the (perhaps low) single-digits millions of dollars range. Another launch (even fully reusable!) would be more than that.

EDIT: A Star-48 is around $6 million, roughly: http://forum.nasaspaceflight.com/index.php?topic=33084.msg1109467#msg1109467
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 02/18/2015 07:45 PM


Okay, so forget that part.  (And I do appreciate the smiley.)  Use the ring trusses as the sole thrust structure and align/dock the stages some other way.  Anything else in the "big concept" that's utterly nonsensical?

Back to the boil off issue, if you are only looking for a single impulse from the two stages then, as long as you dock them and get that impulse in the first orbit you should not have lost too much. However, if one of the reasons you wanted all this extra capacity for a probe included a high energy orbit change later on then you still need to solve the boil off (and operation power issues since the main solar panels won't be deployed until after the last high energy burn). 

I am not seeing how this gets you a solution that is cheaper than 3'rd stage.

There may not be a solution.  This is what you guys call "hand-waving" after all!  But:

1.  The 2nd flight US has a bunch of propellant.  It had no payload, after all, other than the weight of the docking mechanism and any rendezvous sensors/computers.  Maybe it only had a small expendable nosecone rather than a big heavy payload shroud.  Seems like that would make for much larger payload than a 3rd stage added to a single launch.

2.  Common stages, common engines, common propellants, common software, common power, common procedures, common personnel.  All from within SpaceX.  No additional companies, personnel, procedures, safety concerns, or pad mods for a non-common stage.  Each interaction between dissimilar items eats money and poops paper + lost time.

3.  The state of the art wrt cryo boiloff may improve.  People have been working on depot tech for awhile now.

But it is going to slightly more than double the launch cost, giving you a maximum price tag for a 3rd stage that offers the same performance to compete against. If your 2nd launch cost $45M for example that would pay for a substantial 3rd stage.

Another solution would be docking not with a bunch of mechanisms and maneuvers that add risk but with an honest to goodness propellant depot. One that did the hard work of docking and connected to both the propellant inlets and vents and insured a full fuel load or as much as was needed for the mission. It could wait to quite close to launch then let go and back off (and side step too).  We are now talking about an orbit inclined about 26degrees  for efficient servicing from the cape or Boca Chica, and of course launch windows would be instantaneous, but we are now only coordinating a single launch, and if we boiled off a little extra, well that is just a little extra that the depot had to supply. Also our craft doesn't need the anti boil off technology (unless it needs subsequent high energy impulses) only the depot does. This craft would benefit from a far better fuel to empty weight ratio than the docked upper stages as well.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 02/18/2015 07:51 PM
The Falcon 9 - Falcon Heavy upper stage would need a major upgrade to enable it for refuelling. A very much longer loiter time would be one of those. I also would worry more about RP-1 freezing than about some LOX boiloff.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: IainMcClatchie on 02/18/2015 08:39 PM
The trouble I see with Punder's scheme is that, for anything like a geostationary orbit (3910 m/s) or Mars transfer (4270 m/s), most of what you need in low earth orbit is fuel.  So the way to think about it is, the FH boosts an upper stage which is mostly fuel to LEO.  You then have a choice: either replace ~10,000 kg of that fuel with a payload, or boost a slightly larger payload, like that of an F9, and mate it up.

Let me posit a scheme like Punder's, perhaps simpler, to demonstrate the problem.

F9 releases a 13,000 kg object into LEO.  The payload adaptor is different to allow in-space mating.

A FH has an upper stage with no payload but extended tanks.  The shroud is reduced to a little nosecone that gets blown off during ascent.  Once in LEO this US has something like 53,000 kg of propellant left.  It rendezvous and mates with the payload, using the same arrangement that the F9 mated with that payload.

The resulting vehicle has an empty mass of ~18,000 kg, full mass of 71,000 kg, and has available delta-V of 4572 m/s, sufficient to get to geosynchronous orbit (needs 3910 m/s) or Mars intercept (4270 m/s).  Sounds good?

Using the same simple math, a 58,000 kg FH upper stage in LEO can deliver 13,000 kg with 3910 m/s delta-V, or 11,200 kg with 4270 m/s delta-V.  So the extra mating step from the F9 doesn't get you much.  If you want to move more stuff to Mars than FH, you'll need to transfer propellants between FH upper stages, or use, as Punder suggested, one FH upper stage as a booster for a second FH upper stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: abaddon on 02/18/2015 08:49 PM
Maybe we should stop trying to pack all the energy for any given mission into a single launch.  ...
For anything like this, multiple launches don't make any sense.

I'm not sure of the exact figures, but I'm pretty sure a small solid rocket kick motor is in the (perhaps low) single-digits millions of dollars range. Another launch (even fully reusable!) would be more than that.

EDIT: A Star-48 is around $6 million, roughly: http://forum.nasaspaceflight.com/index.php?topic=33084.msg1109467#msg1109467

But a Star-48 wouldn't accomplish the overriding goal of two launches and LEO rendezvous and ...

Wait, that's not the goal?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 02/18/2015 08:55 PM
F1US and it's Kestrel engine flew several times. It could provide the basis for a kick stage, though I believe it's only ~4t. Extra mass would be no problem as gravity losses are not an issue for a kick stage.

But, I wonder about a methalox Kestrel. Assumption is that the engineering that coped with LOX could be co-opted to deal with LCH4.

Big downside - such a large diversion from flight history would basically be a new stage, with no opportunities to demonstrate it before it gets used for something critical. (Unless it could fly as a secondary on F9R-Dev2 flights from NM?)

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 02/18/2015 09:09 PM
The Falcon 9 - Falcon Heavy upper stage would need a major upgrade to enable it for refuelling. A very much longer loiter time would be one of those. I also would worry more about RP-1 freezing than about some LOX boiloff.

Why major, why couldn't the the fuel depot attach to all the existing umbilical points? giving it the ability to circulate propellants (thereby controlling temps) and to provide power to the US and payload to keep it fresh?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 02/18/2015 09:20 PM
The Falcon 9 - Falcon Heavy upper stage would need a major upgrade to enable it for refuelling. A very much longer loiter time would be one of those. I also would worry more about RP-1 freezing than about some LOX boiloff.

Why major, why couldn't the the fuel depot attach to all the existing umbilical points? giving it the ability to circulate propellants (thereby controlling temps) and to provide power to the US and payload to keep it fresh?

At the very least the stage must remain alive and active until docking is achieved.

Also connections to the stage made in the HIF are not the same as needed for automated docking to a fuel depot. It needs a redesign.

I have the very strong opinion it won't be done for a Falcon upper stage. It will need to be done for the BFR upper stage. But that would be designed from the beginning with this in mind.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AncientU on 02/18/2015 10:37 PM
The Falcon 9 - Falcon Heavy upper stage would need a major upgrade to enable it for refuelling. A very much longer loiter time would be one of those. I also would worry more about RP-1 freezing than about some LOX boiloff.

Why major, why couldn't the the fuel depot attach to all the existing umbilical points? giving it the ability to circulate propellants (thereby controlling temps) and to provide power to the US and payload to keep it fresh?

At the very least the stage must remain alive and active until docking is achieved.

Also connections to the stage made in the HIF are not the same as needed for automated docking to a fuel depot. It needs a redesign.

I have the very strong opinion it won't be done for a Falcon upper stage. It will need to be done for the BFR upper stage. But that would be designed from the beginning with this in mind.

Agree that it won't be done for the existing F9 upper stage, but could easily design a new upper for FH with refueling and loiter capability from the beginning.  GS stated that 'lots' of FH launches could head for Mars... Seems that no one would use this launcher for planetary missions with existing configuration.  Refueling is also on the SpaceX docket -- FH is the perfect proving ground before BFR arrives on the scene.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 02/19/2015 01:30 PM
F1US and it's Kestrel engine flew several times. It could provide the basis for a kick stage, though I believe it's only ~4t. Extra mass would be no problem as gravity losses are not an issue for a kick stage.

IMHO, a version of the Kestrel, possibly using F-1e U/S tanking, would be ideal for a lot of in-space applications. Especially if it's modified to use LCH4 rather than RP1, thus removing the 'coking' issue.

That said, I maintain my position that, in the event of the payload needing a kick stage, I think that it is more likely that SpaceX will require the customer to provide it (although they will probably still do the booster/payload integration).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/19/2015 02:31 PM
Maybe we should stop trying to pack all the energy for any given mission into a single launch.  ...
For anything like this, multiple launches don't make any sense.

I'm not sure of the exact figures, but I'm pretty sure a small solid rocket kick motor is in the (perhaps low) single-digits millions of dollars range. Another launch (even fully reusable!) would be more than that.

EDIT: A Star-48 is around $6 million, roughly: http://forum.nasaspaceflight.com/index.php?topic=33084.msg1109467#msg1109467

But a Star-48 wouldn't accomplish the overriding goal of two launches and LEO rendezvous and ...

Wait, that's not the goal?

Of course it's not the goal, but the snark was funny!   ;D

I'm just thinking about how booster recovery throws a monkey wrench into assumptions that have held since the 1950s.  Three complete boosters, 27 Merlins, that aren't "sunk cost".  (Rimshot) 

That's my main concern.  Concepts long discarded may become feasible with that kind of cost savings.  Maybe not this particular concept from some nobody on the Internet, but you see my point.

Anyway... The 2nd flight US is big.  Extra fuel mass that would otherwise be payload.  It's a super-US.  the partially depleted 1st flight US is now the "kick stage" for what is effectively a bigger rocket.  And because of booster reuse, all youve expended is a second US, NOT a second Falcon Heavy.

You might say that stretching the US tanks for this application is a major cost, and running two FH launches near-simultaneously is difficult and dangerous, or developing and proving the docking scheme is a huge project.  Maybe.  What are they compared to developing and implementing orbital depot infrastructure?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/19/2015 03:25 PM
That's my main concern.  Concepts long discarded may become feasible with that kind of cost savings.  Maybe not this particular concept from some nobody on the Internet, but you see my point.

This!!!

Bring out those retired visionaries from both sides of the Atlantic and dust off those old bindered studies from when cost was no object (until someone actually tried to spend the money). 

We've spend a lot of breath on the economic of reusability, and a good deal of it was conceptualizing missions to take advantage of it....

Thank you!

I guess another idea would be to break up your payload (if possible) and eliminate kick stages altogether.  This would have the added advantage that in case of launch failure, you lose only half your stuff.  For example, a planetary probe with a lander, like Cassini/Huegens.  Send the orbiter on one flight, the lander on another.  Reusable stages lower the overall launch cost, and you are now dividing your eggs between two baskets.  Both payloads can be built with more capability because they no longer have to attach and interface with each other, and trajectories can be optimized for each.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: abaddon on 02/19/2015 03:50 PM
This is like talking about moving the house across the street to this side of the street so you don't have to cross the street to get to it.

A Star-48 is proven, relatively cheap, with only minor well-understood integration considerations.  It is a no-brainer way for SpaceX to be able to provide high-energy escape trajectories for the small number of payloads that require it.  Successful booster recovery and reuse doesn't throw any "wrench" into anything.  It makes any mission cheaper.  It doesn't mean it makes it sensible to throw multiple launches and all of the complexity that would entail at something that a $6 million kick stage solves.

There are other concepts that could greatly benefit from something like the proposed architecture, but this isn't one of them.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: punder on 02/19/2015 04:05 PM
This is like talking about moving the house across the street to this side of the street so you don't have to cross the street to get to it.

A Star-48 is proven, relatively cheap, with only minor well-understood integration considerations.  It is a no-brainer way for SpaceX to be able to provide high-energy escape trajectories for the small number of payloads that require it.  Successful booster recovery and reuse doesn't throw any "wrench" into anything.  It makes any mission cheaper.  It doesn't mean it makes it sensible to throw multiple launches and all of the complexity that would entail at something that a $6 million kick stage solves.

There are other concepts that could greatly benefit from something like the proposed architecture, but this isn't one of them.

You are right, I went off on a tangent.  Sorry.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dror on 02/20/2015 06:50 AM
If WE are thinking about FH upper stage,  the next probabal step is a single raptor.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 02/20/2015 10:42 AM
If WE are thinking about FH upper stage,  the next probabal step is a single raptor.

I've long wondered if any performance advantage can be gained from a methane-fuelled Merlin upper stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/20/2015 03:34 PM
If WE are thinking about FH upper stage,  the next probabal step is a single raptor.

I've long wondered if any performance advantage can be gained from a methane-fuelled Merlin upper stage.

But they have all but ruled it out. It would lose commonality with F9, and FH is already providing more capability than there is demand for.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/23/2015 04:47 PM
My first stab at a real Falcon Heavy page, after holding out for a while. 
www.spacelaunchreport.com/falconH.html (http://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
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AJW on 02/23/2015 06:04 PM
You should archive this current page since it will be interesting to see the changes as new details emerge.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate 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 (http://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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 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
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco on 02/23/2015 10:34 PM
How would prop densification and thrust increase improve FH GEO payload with RTLS ?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: PahTo 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?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kabloona 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
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: PahTo 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...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 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
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: S.Paulissen on 02/25/2015 12:57 AM
Out of curiosity, what have you included as variables in your simulations?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrueBlueWitt 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 [email protected]% at 200klb that would offset Grav losses for S2 even with the extra prop.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 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
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 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
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott 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?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Owlon 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.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH 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?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/25/2015 11:07 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

Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrueBlueWitt on 02/26/2015 01:11 AM
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

Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

My guess is that side cores will run at 100%(vs today's 85%) and the center core will still be able to throttle down as far as current 85% M1D can.. so that allows you to conserve a lot of core prop, and stage lower for the boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deruch on 02/26/2015 01:19 AM
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

Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

With the planned higher thrust operation (M1D+), assuming that there aren't changes to the M1D which would raise the lower limit, the throttle range will increase even more.  ~10% lower throttle limit (e.g. from 70% to 60%).

edit: pipped at the post by truebluewitt
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 02/26/2015 02:49 AM
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

Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

You surely have not read carefully. Go back and re-read please!!! (sigh)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/26/2015 04:06 AM

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

Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

You surely have not read carefully. Go back and re-read please!!! (sigh)

Perhaps you should re-read what I wrote (bold text).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 02/26/2015 04:26 AM
Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

From what I've heard, the boosters have already been stretched to the maximum extent possible.  Any longer and they would not be road transportable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/26/2015 04:35 AM
Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

From what I've heard, the boosters have already been stretched to the maximum extent possible.  Any longer and they would not be road transportable.
Regardless, the boosters on the Falcon Heavy are stretched, end of story. But in your defense, I guess the Falcon Heavy boosters (I believe?) did have a slight run-in with an overpass or something on their way to Texas. :D
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 02/26/2015 12:56 PM
From what I've heard, the boosters have already been stretched to the maximum extent possible.  Any longer and they would not be road transportable.
The *Falcon 9* has been stretched as far as possible (as far as we know).  It's not road-transport which is the issue (that's the constraint on the *diameter* of the stage), it's the bending modes. A wobbly thin rocket is tricky to push from the bottom. (See Fineness ratio (http://en.m.wikipedia.org/wiki/Fineness_ratio) on the wiki.). But when you take the second stage and payload off the boosters, you apparently gain the ability to do some extra stretch on them.  Which makes sense, right? Naively you'd think you could extend the boosters to at least the size of S1+S2 on the core, and the amount of stretch depicted is much more modest (roughly the size of the interstage).

Note that the SpaceX illustration on its website (http://www.spacex.com/falcon-heavy) shows stretched boosters, but the recently-released Falcon Heavy rendered video on YouTube site apparently does not.  This is a matter of heated debate (http://forum.nasaspaceflight.com/index.php?topic=36660.0), which I don't want to rehash.  Perhaps the crossfeed decision is involved.  We'll just say that everything's a bit up-for-grabs until we see some pictures of actual flight hardware.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/26/2015 01:32 PM
Regardless, the boosters on the Falcon Heavy are stretched, end of story. But in your defense, I guess the Falcon Heavy boosters (I believe?) did have a slight run-in with an overpass or something on their way to Texas. :D
Unfortunately, it isn't the end of the story.  The big diagrams of Falcon Heavy on the SpaceX web site show what might be stretched boosters, but the recent video release showed boosters that looked the same length as the core with the extra space above the tanks used to support grid fins, etc.  Also, I seem to remember SpaceX officials stating that the core and boosters would be identical, or nearly so.

As always with SpaceX, we won't know for sure until someone posts a photo of the actual rocket.

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/26/2015 02:01 PM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: foltster on 02/26/2015 03:27 PM
I look at it this way.

The interstage is basically part of the first stage.  Since there is no need for the interstage on the side boosters they might as well extend the tanks that far.


Or....do they need something akin to the interstage for the side booster grid fins and avionics?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 02/26/2015 03:59 PM
I look at it this way.

The interstage is basically part of the first stage.  Since there is no need for the interstage on the side boosters they might as well extend the tanks that far.

I think the interstage is attached at the launch site (or at CCAFS), but I could be wrong.


Or....do they need something akin to the interstage for the side booster grid fins and avionics?

Yes, the nose cone needs to contain the thrusters (+propellant) and the grid fins. I suspect a much shorter trunk section is added before the nose cone.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: StuffOfInterest on 02/26/2015 04:16 PM
I would support the idea that the tank stretch will take up the same (or most of the same) space as the current interstage as most of that length is for the MVac nozzle.  However, if they do reach a point where they need a longer vehicle than current road transport allows there is an alternative.  Ship it in two sections, one for the RP and one for the LOX tank.  Weight wise it costs you one additional bulkhead since you wouldn't have a common bulkhead anymore but you can join the two sections similar to how you would join stage one and stage two.  Probably a few more bolts so everything stays together for landing.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 02/26/2015 04:30 PM
Ship it in two sections, one for the RP and one for the LOX tank.  Weight wise it costs you one additional bulkhead since you wouldn't have a common bulkhead anymore but you can join the two sections similar to how you would join stage one and stage two.  Probably a few more bolts so everything stays together for landing.

Non starter. 
1.There is a difference in the mating. 
2.  There is more than just the mechanical mate.  There is the propellant feed line of the upper tank.  There are other fluid lines, there are power and data harnesses. 
3.  There is the extra time needed at the launch site to perform the operation that will limit throughput
4.  there is the extra GSE needed. (minimum two more support stands)
5.  So how is the hot fire in TX performed?  Is the stage assembled for hot fire and then disassemble.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/26/2015 05:29 PM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.
Who?

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/26/2015 05:32 PM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.
Who?

 - Ed Kyle
SpaceX multiple times and Jim.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/26/2015 05:46 PM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.
Who?

 - Ed Kyle
SpaceX multiple times and Jim.
Maybe all three are stretched from v1.1. That would make sense.  Boosters carrying more propellant than core makes no sense unless crossfeed is used, which is apparently not going to be the case.  There is no performance advantage.  If anything, there is a performance penalty. 

Meanwhile, we have these images to ponder.

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: LouScheffer on 02/26/2015 06:46 PM
From what I've heard, the boosters have already been stretched to the maximum extent possible.  Any longer and they would not be road transportable.
The *Falcon 9* has been stretched as far as possible (as far as we know).  It's not road-transport which is the issue (that's the constraint on the *diameter* of the stage), it's the bending modes. A wobbly thin rocket is tricky to push from the bottom.
If you were sufficiently brave (or perhaps foolhardy) you could use active control of bending modes.   The Falcon should be in a particularly good position to do this, if it's willing to use the grid fins on the way up.

The engines, on the end of the rocket) are in a good place to help control first order bending modes.  But you could only control these first-order modes, since you've only got two degrees of control (thrust angle in 2D) and two first order modes (x & y, if the rocket's length is z).

But the Falcon family has another possible weapon in the fight against bending modes - the grid-fins.  If they were deployed on the way up they could actively damp second-order modes in addition.  Fortunately, they are not on the end of the rocket, which gives them a different influence on the various modes, compared to the engines.  They could also help control torsional modes.

I seriously doubt they would try this, but it would be really cool from an engineering point of view.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarekCyzio on 02/26/2015 06:55 PM
Boosters carrying more propellant than core makes no sense unless crossfeed is used, which is apparently not going to be the case.  There is no performance advantage.  If anything, there is a performance penalty. 

I am not an expert, so could you elaborate more on why this would not provide any performance advantage? Center core will be throttled down = it feels like the more propelant you have in boosters, the higher delta V you can give to the center core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 02/26/2015 08:20 PM
Boosters carrying more propellant than core makes no sense unless crossfeed is used, which is apparently not going to be the case.  There is no performance advantage.  If anything, there is a performance penalty. 

I am not an expert, so could you elaborate more on why this would not provide any performance advantage? Center core will be throttled down = it feels like the more propelant you have in boosters, the higher delta V you can give to the center core.

The core has to "outlast" the boosters for a given upper stage, otherwise you are just wasting most of their effort
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/26/2015 09:03 PM
Boosters carrying more propellant than core makes no sense unless crossfeed is used, which is apparently not going to be the case.  There is no performance advantage.  If anything, there is a performance penalty. 

I am not an expert, so could you elaborate more on why this would not provide any performance advantage? Center core will be throttled down = it feels like the more propelant you have in boosters, the higher delta V you can give to the center core.
The comparison I made is for a given GLOW, assumes no crossfeed, and assumes full recovery of boosters and core.  The choice is between all three cores being identical and having the boosters carry, say, 10% more propellant than the core.  In my modeling, I find that the identical cores example provides slightly more LEO payload than the bigger boosters example, partly because there is less propellant left in the core at staging for the latter.  The goal isn't just to boost the core to some velocity, it is also to stage it with as much propellant still on board as possible.  The longer-burning boosters would cause the core to burn more propellant before staging.

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarekCyzio on 02/26/2015 09:13 PM
The longer-burning boosters would cause the core to burn more propellant before staging.

Can't the core be throttled even more? Or some core engines may even be shut down to save fuel? But I think I see your point - adding more fuel to boosters makes them carry their own weight for a longer period and the goal is to get rid of the boosters as soon as possible.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/26/2015 09:16 PM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.
Who?

 - Ed Kyle
SpaceX multiple times and Jim.
Maybe all three are stretched from v1.1. That would make sense.  Boosters carrying more propellant than core makes no sense unless crossfeed is used, which is apparently not going to be the case.  There is no performance advantage.  If anything, there is a performance penalty. 

Meanwhile, we have these images to ponder.

 - Ed Kyle
The interstage, man.

Also, there IS a performance advantage. Merlin 1D can throttle widely (and can relight). That provides much the performance advantage that cross-feed does.

EDIT:Okay, I would still take the bet that they're stretched, but you've made a good enough case that I wouldn't offer you 20:1 odds.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/26/2015 09:29 PM
The longer-burning boosters would cause the core to burn more propellant before staging.
Can't the core be throttled even more? Or some core engines may even be shut down to save fuel? But I think I see your point - adding more fuel to boosters makes them carry their own weight for a longer period and the goal is to get rid of the boosters as soon as possible.
The longer-burning boosters would cause the core to burn more propellant before staging.

Can't the core be throttled even more? Or some core engines may even be shut down to save fuel? But I think I see your point - adding more fuel to boosters makes them carry their own weight for a longer period and the goal is to get rid of the boosters as soon as possible.
The core can be throttled to the minimum for both cases, but will still have less propellant left for the longer-burning booster example.  The only advantage of a longer booster would be if it transferred propellant to the core while still attached, but crossfeed seems unlikely to appear for awhile if ever.

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 02/26/2015 09:47 PM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.

I'll take the bet.  20:1 odds are pretty good!

I think unstretched boosters makes sense given SpaceX's incremental development philosophy, plus the fact that FH is already rather late.

FHv1: unstretched boosters, no crossfeed, identical tanks, interstage & grid fins for all cores, "just" stage interconnects, core throttling, and everything else which is "essential" for FH.  Get 'er flying ASAP!
FHv1.1: stretched boosters, new interstage for boosters, grid fin relocation, etc.  Probably all in development, just not on the critical path for first flight anymore.  Low-hanging fruit.
FHv1.2: crossfeed.  Developed only if/when a customer has need, may be bypassed by current events.
...
FHv2: S2 reusability? (A man can dream!)

That seems like a nice incremental development path, assuming that all three of FHv1, FHv1.1, FHv1.2 offer monotonic performance improvements over F9R.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Semmel on 02/27/2015 11:19 AM
Do we have any knowledge what payload the first FH will have and where it would be going? I am looking for actual information here, not speculation.

I couldnt really find info on that question. From Shit Elon Sais from a talk in 2011 which is quite outdated. (Thx QuantumG !!!)  link (http://shitelonsays.com/transcript/spacex-next-falcon-heavy-press-conference-2011-04-05)
Quote
The first mission is really a demonstration flight. It's there to prove that Falcon Heavy will work. That it will deliver the payload that we say it can, and we don't have a primary customer for it, but we are likely to have several smaller secondary satellites on-board that will do a variety of things, and if we get lucky, maybe there will be a big satellite at the last minute that wants to buy the flight at a reduced price.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco on 02/28/2015 12:52 AM
I would give you 20:1 odds and still take the bet. The boosters are stretched, we have it from multiple sources.

I'll take the bet.  20:1 odds are pretty good!

I think unstretched boosters makes sense given SpaceX's incremental development philosophy, plus the fact that FH is already rather late.

FHv1: unstretched boosters, no crossfeed, identical tanks, interstage & grid fins for all cores, "just" stage interconnects, core throttling, and everything else which is "essential" for FH.  Get 'er flying ASAP!
FHv1.1: stretched boosters, new interstage for boosters, grid fin relocation, etc.  Probably all in development, just not on the critical path for first flight anymore.  Low-hanging fruit.
FHv1.2: crossfeed.  Developed only if/when a customer has need, may be bypassed by current events.
...
FHv2: S2 reusability? (A man can dream!)

That seems like a nice incremental development path, assuming that all three of FHv1, FHv1.1, FHv1.2 offer monotonic performance improvements over F9R.
The snag is USAF/NASA certification, unless they could upgrade with a single launch to confirm everything is ok, SpaceX has a big incentive for doing all much as possible on V1.0.
Besides, what does SpaceX has to learn from FH, compared to everything they got through already ? Yes, there are variables, but it seems from F9R to FH v1.0 its less of a leap than from F9 to F9R. So go to what you consider FHv1.1 directly instead.
FH might be 50% DoD missions long run. That tends to prevent SpaceX from doing major incrementalism.
Finally, most missions conceived (and all booked) for FH don't need anything beyond FHv1.1. Leave something for BFR.

The one way to enable incrementalism is recovery of all 3 stages, which would enable upgrading lots of F9R launches to FH at minimal cost, while giving them lots of flight data to certificate from. However I would think USAF wouldn't be too fond of 3 certifications.

Also, with Dragon2 and FH mostly done frees up resources to focus on BFR designs. I would hope the simpler upscaled F9R using Raptor engines could see major design work start 2016.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Space Ghost 1962 on 02/28/2015 01:39 AM
Keep in mind payloads and who you sell capacity to.

FH commercial payloads (GSO) that launch on Ariane V only are a prime candidate.

AV 551 and DIVH govt payloads are other prime candidates. Keep also in mind likely orbital insertion requirements.

For now that's all you'd need to certify under a single configuration called FH.

There are only two much bigger payload sources - theoretically NASA and, of course, someone else who has ambitions for Mars. For these two, likely a "special case" arrangement might be in order. Also still called FH.

You don't really need more, do you?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cuddihy on 02/28/2015 04:14 AM
Ok, I'm aware this sound insane from a risk standpoint. But what if you not only throttled down the core engines but actually shut down the center engine as well? They've had a lot of experience now re-lighting it, just not while the other ones are running. So you throttle the core mains to say 80% and shut down the center engine while the boosters keep burning at 115%. Now you'd have almost half the fuel left in the core when you stage. That's significant.  If the stage can survive this thrust differential at Max Q, and the additional gravity losses...hmm, needs more work...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/28/2015 04:15 AM
They relight 3 engines, not just the center one.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cuddihy on 02/28/2015 04:34 AM
Yes, but shutting those down 30s into flight, that would be missing another 220,000 lbf of first stage thrust you need to get to orbit. There are limits...you'd get close to overall vehicle thrust < weight. Bad for gravity losses.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Nilof on 02/28/2015 10:55 AM
Question: how much will the increased thrust of the Merlin 1D+ affect the benefits of crossfeed? If the side boosters have more thrust, you can throttle down the center core more without being eaten up alive by gravity drag, and the benefits of crossfeed should be smaller.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/28/2015 01:14 PM
Question: how much will the increased thrust of the Merlin 1D+ affect the benefits of crossfeed? If the side boosters have more thrust, you can throttle down the center core more without being eaten up alive by gravity drag, and the benefits of crossfeed should be smaller.
Precisely.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 02/28/2015 02:05 PM
Ok, I'm aware this sound insane from a risk standpoint. But what if you not only throttled down the core engines but actually shut down the center engine as well? They've had a lot of experience now re-lighting it, just not while the other ones are running. So you throttle the core mains to say 80% and shut down the center engine while the boosters keep burning at 115%. Now you'd have almost half the fuel left in the core when you stage. That's significant.  If the stage can survive this thrust differential at Max Q, and the additional gravity losses...hmm, needs more work...
If engines aren't needed, why have them at all?  Thrust costs money.

It seems more likely that the rocket is designed to use, and need, the thrust.

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 02/28/2015 02:46 PM
Re: certification --- it may well be that FHv1.1 is the version they get certified.   And the gap between v1 and v1.1 needn't be long. This is exactly how F9 development worked. F9v1.0 flew for only a few flights, F9v1.1 is the variant that got certified.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/28/2015 02:55 PM
Ok, I'm aware this sound insane from a risk standpoint. But what if you not only throttled down the core engines but actually shut down the center engine as well? They've had a lot of experience now re-lighting it, just not while the other ones are running. So you throttle the core mains to say 80% and shut down the center engine while the boosters keep burning at 115%. Now you'd have almost half the fuel left in the core when you stage. That's significant.  If the stage can survive this thrust differential at Max Q, and the additional gravity losses...hmm, needs more work...
If engines aren't needed, why have them at all?  Thrust costs money.

It seems more likely that the rocket is designed to use, and need, the thrust.

 - Ed Kyle
Huh? Where'd you get that from? You'd still want full thrust right at lift-off but throttle down the core (perhaps shut down an engine or two) soon after then throttle the core to full right after the boosters stage off.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 02/28/2015 04:36 PM
Ok, I'm aware this sound insane from a risk standpoint. But what if you not only throttled down the core engines but actually shut down the center engine as well? They've had a lot of experience now re-lighting it, just not while the other ones are running. So you throttle the core mains to say 80% and shut down the center engine while the boosters keep burning at 115%. Now you'd have almost half the fuel left in the core when you stage. That's significant.  If the stage can survive this thrust differential at Max Q, and the additional gravity losses...hmm, needs more work...
If engines aren't needed, why have them at all?  Thrust costs money.

It seems more likely that the rocket is designed to use, and need, the thrust.

 - Ed Kyle

The reader is supposed to draw an inference that said engine(s) run when needed-at liftoff and after booster separation. In essence they're throttling down-all the way down to 0% before throttling back up after boosters are gone.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: sanman on 02/28/2015 08:15 PM
I'm curious - does Falcon Heavy automatically fall under the Reusable Rockets category?

Is there any mission type where none of it gets retrieved or re-used?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/28/2015 08:18 PM
I'm curious - does Falcon Heavy automatically fall under the Reusable Rockets category?

Is there any mission type where none of it gets retrieved or re-used?
Yeah, anything which needs its full performance. None really exist, yet, except maybe some high energy missions like New Horizons.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: sanman on 02/28/2015 08:27 PM
Yeah, anything which needs its full performance. None really exist, yet, except maybe some high energy missions like New Horizons.

But not even the side-boosters get recovered in that case?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 02/28/2015 08:39 PM
Yeah, anything which needs its full performance. None really exist, yet, except maybe some high energy missions like New Horizons.

But not even the side-boosters get recovered in that case?
Not if you really, really need the performance (although for high energy, a small kick stage may be cheaper than throwing away 2 boosters).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Space Ghost 1962 on 02/28/2015 09:19 PM
I'm curious - does Falcon Heavy automatically fall under the Reusable Rockets category?
Suggest you look at "reusable" as a mode or part of a evolving CONOPs at a longer scale.

In essence, all F9/FH are in a sense "reusable". They get a full initial burn on a test stand as a "first flight", and then move on to CCAFS/VBG. Possibly a static fire, then launch.

If they get recovered, if convenient to the mission and successful recovery, they get a chance at yet another mission, given enough lifetime in the asset remaining. Perhaps ASDS is more a means of stretching this, trading off turn around time for reduced resource consumption.

Other than that, so called F9/FH/F9R/FHR are convenient components for missions to use them.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco on 03/01/2015 03:37 AM
Yeah, anything which needs its full performance. None really exist, yet, except maybe some high energy missions like New Horizons.
Ok, but there are no unawarded new horizons type missions, right ?
Doesn't it make more sense to leave those type missions for Raptor rockets instead ?
Pick the battles you can win, and those you might not win, but some other spoils can come from.
SpaceX has its plate full.
I don't think SpaceX will end up doing any fully expendable FH missions.
At a minimum recovery of the side boosters.
With recovery of the side boosters, F9R + FHR can do what, 95% of all missions up to date ?
Anyhow, what payload class is new horizons ? Is it the same type as JWST ?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/01/2015 06:22 AM
I don't think SpaceX will end up doing any fully expendable FH missions.
At a minimum recovery of the side boosters.
With recovery of the side boosters, F9R + FHR can do what, 95% of all missions up to date ?

I wondered about Red Dragon missions. Those may stretch the limits of what FH can do with booster recovery.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 03/01/2015 06:26 AM


Yeah, anything which needs its full performance. None really exist, yet, except maybe some high energy missions like New Horizons.
Ok, but there are no unawarded new horizons type missions, right ?
Doesn't it make more sense to leave those type missions for Raptor rockets instead ?
Pick the battles you can win, and those you might not win, but some other spoils can come from.
SpaceX has its plate full.
I don't think SpaceX will end up doing any fully expendable FH missions.
At a minimum recovery of the side boosters.
With recovery of the side boosters, F9R + FHR can do what, 95% of all missions up to date ?
Anyhow, what payload class is new horizons ? Is it the same type as JWST ?

SpaceX want to expand the market. Specifically, they want to be able to send big payloads to Mars.

Asking about current payloads has its place (what can / will fly medium term), but doesn't illuminate how SpaceX may decide to evolve FH. (Or, it might, depending on how long they think it will be before any changes to the market.)

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 03/01/2015 02:00 PM
Soar probe plus has yet to be awarded
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JamesH on 03/01/2015 04:30 PM
Ok, I'm aware this sound insane from a risk standpoint. But what if you not only throttled down the core engines but actually shut down the center engine as well? They've had a lot of experience now re-lighting it, just not while the other ones are running. So you throttle the core mains to say 80% and shut down the center engine while the boosters keep burning at 115%. Now you'd have almost half the fuel left in the core when you stage. That's significant.  If the stage can survive this thrust differential at Max Q, and the additional gravity losses...hmm, needs more work...
If engines aren't needed, why have them at all?  Thrust costs money.

It seems more likely that the rocket is designed to use, and need, the thrust.

 - Ed Kyle
Huh? Where'd you get that from? You'd still want full thrust right at lift-off but throttle down the core (perhaps shut down an engine or two) soon after then throttle the core to full right after the boosters stage off.

If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket. After all the second stage isn't lit until later in flight. Or does the maths simply not work out?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: S.Paulissen on 03/01/2015 05:35 PM
If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket. After all the second stage isn't lit until later in flight. Or does the maths simply not work out?

If you do not light center core engines until booster cores' separation, that is the canonical definition of a three stage rocket.  If you do light the center core engines before separation it's a 'hybrid' 2.5 stage rocket, for lack of a better term. 

EDIT: Really the idea of a 'stage' is a conceptual construct we use to describe a rocket that is much more nuanced and flexible in reality.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JamesH on 03/02/2015 08:59 AM
If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket. After all the second stage isn't lit until later in flight. Or does the maths simply not work out?

If you do not light center core engines until booster cores' separation, that is the canonical definition of a three stage rocket.  If you do light the center core engines before separation it's a 'hybrid' 2.5 stage rocket, for lack of a better term. 

EDIT: Really the idea of a 'stage' is a conceptual construct we use to describe a rocket that is much more nuanced and flexible in reality.

I was really thinking of a stack rather than side by side, but your point is clearly correct!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/02/2015 09:55 AM
Why is that problematic? It is the intent to run the core at reduced thrust until booster staging. (it throttles down just after liftoff) Delta IV Heavy operates the same way. M1D has enough of a throttle range to still make that possible with slightly stretched boosters.

From what I've heard, the boosters have already been stretched to the maximum extent possible.  Any longer and they would not be road transportable.
Regardless, the boosters on the Falcon Heavy are stretched, end of story. But in your defense, I guess the Falcon Heavy boosters (I believe?) did have a slight run-in with an overpass or something on their way to Texas. :D

The center core has the interstage permanently attached, and I believe its transported that way.  So from a road transport point of view, the FH boosters may be about the same length as the center core.  In fact, if they leave off the domes for transport, the boosters would actually be a little shorter.

My point is that the all 3 of the first stage cores are already stretched as far as they can go.  Any longer and they would no longer be road transportable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 03/02/2015 07:14 PM

If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket. After all the second stage isn't lit until later in flight. Or does the maths simply not work out?

I think you'd need the central core burning to get FH off the pad.  But they probably could be shut down shortly into ascent.  Since the Merlin can be relit after shutdown, it could stay off until booster sep, and then relight.  Gravity losses may be a little more in this ascent profile, but the benefit would be the stack is going pretty low and slow at booster sep so they should be pretty easy to recover at LC-13 without the central core helping very much prior to that point.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: hrissan on 03/02/2015 08:23 PM

If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket. After all the second stage isn't lit until later in flight. Or does the maths simply not work out?

I think you'd need the central core burning to get FH off the pad.  But they probably could be shut down shortly into ascent.  Since the Merlin can be relit after shutdown, it could stay off until booster sep, and then relight.  Gravity losses may be a little more in this ascent profile, but the benefit would be the stack is going pretty low and slow at booster sep so they should be pretty easy to recover at LC-13 without the central core helping very much prior to that point.
SpaceX may have an increased confidence in restarting engines now... May be shutting down engines on the center core and then starting them again does not sound that dangerous any more (after so many successfull restarts for reentry and landing).

And BTW some missions rely on perfect MVac restart, so working out any bugs in restart process is of paramount importance anyway.

If 1/9 or maybe even 2/9 engines on the center core will fail to restart, well that counts as an engine-out, would complete mission anyway.

How many engines could be shut off IMHO depends on the loads in the thrust structure resulting from thrust difference, do not have any idea, but if 6 engines could be shut off, the core could be more than 50% full at the separation, which is marvelous.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/02/2015 08:26 PM
Sigh. That's not gonna happen. M1D can throttle to 50% - perhaps even lower - and this is more than enough to leave propellant in the core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JamesH on 03/03/2015 09:39 AM
Sigh. That's not gonna happen. M1D can throttle to 50% - perhaps even lower - and this is more than enough to leave propellant in the core.

Sigh. Thanks for the information.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: S.Paulissen on 03/03/2015 12:38 PM
Sigh. That's not gonna happen. M1D can throttle to 50% - perhaps even lower - and this is more than enough to leave propellant in the core.

I'm curious, do you have a source for this 50% throttle capability?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/03/2015 04:04 PM
Sigh. That's not gonna happen. M1D can throttle to 50% - perhaps even lower - and this is more than enough to leave propellant in the core.

I'm curious, do you have a source for this 50% throttle capability?

This twitter post: https://twitter.com/elonmusk/status/462104679116050432

Yes, some think he means a 40% throttle range, but I don't. Because I do recall a NASA presentation of the F9v1.1 clearly indicating a 50% M1DVac throttle capability, and I would expect the M1D to have a similar range, so the range should be at lest 50% - probably the 60% that Elon hints at.

It is also possible that this new thrust upgrade of the M1D increases that range by merely increasing the top rated thrust level.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 03/03/2015 07:44 PM
If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket.

I thought second stage meant core until I read this:

I was really thinking of a stack rather than side by side

Second stage engines cannot be used at launch. They cannot be used until the first stage is jettisoned, therefore you would not shut them down, because you cannot light them while the first stage is running. Think about it, if you light the second stage while the first stage is still firing, the T/W on stage 1 is higher than stage 2; stage 2 cannot pull away from stage 1; the flame from stage 2 would likely ignite any prop still in stage 1. (I know, there are rare exceptions.) Stage 1 has MECO (main engine cut off). Stage 1 jettisons. Interstage adaptor jettisons (on most rockets, but not this one). Stage 2 ignites. This is very basic..
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/03/2015 08:38 PM
Maybe all three are stretched from v1.1.

From the SpaceX website:

http://www.spacex.com/falcon9
Height 68.4 m 224.4 ft

http://www.spacex.com/falcon-heavy
Height 68.4 m 224.4 ft
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JamesH on 03/04/2015 09:53 AM
If you shut down all the engines on the second stage (or didn't use them at all for launch) is that the same a making it a three stage rocket.

I thought second stage meant core until I read this:

I was really thinking of a stack rather than side by side

Second stage engines cannot be used at launch. They cannot be used until the first stage is jettisoned, therefore you would not shut them down, because you cannot light them while the first stage is running. Think about it, if you light the second stage while the first stage is still firing, the T/W on stage 1 is higher than stage 2; stage 2 cannot pull away from stage 1; the flame from stage 2 would likely ignite any prop still in stage 1. (I know, there are rare exceptions.) Stage 1 has MECO (main engine cut off). Stage 1 jettisons. Interstage adaptor jettisons (on most rockets, but not this one). Stage 2 ignites. This is very basic..

Sorry, I did mean core, not second stage, and my comparison was against a stack, i.e. a two stage three cored first stage rocket where the centre core was not lit at launch (or turned off soon after), compared with a three stage stack. Are they equivalent, or are there benefits/disadvantages. Which I suspect has been answered in the posts above.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/04/2015 12:01 PM
It's not road-transport which is the issue (that's the constraint on the *diameter* of the stage), it's the bending modes.
Road transport constraints involve both core diameter and core length.

The boosters are stretched, we have it from multiple sources.
I agree.  But again, if you include the interstage as an integral part the center core, the length of all 3 cores is pretty close.  In fact, if you remove the domes, the booster cores would be shorter.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 03/04/2015 03:15 PM
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks. So, a larger core tank would seem to make sense.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: fthomassy on 03/04/2015 04:24 PM
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks. So, a larger core tank would seem to make sense.
The one diagram I recall showed cross feed between distribution nodes that feed all engines on a particular core.  So the center core has a node that is fed by three tanks and distributing to all nine engines.  That diagram was very cartoonish but it also seems more intuitive.  Either way I don't see the relationship to tank size.  Same size core and boosters or not ... cross feed or not ... lots of choices to spend money (or not) for performance options.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cdleonard on 03/04/2015 05:05 PM
I agree.  But again, if you include the interstage as an integral part the center core, the length of all 3 cores is pretty close.  In fact, if you remove the domes, the booster cores would be shorter.
The interstage protects the upper-stage engine. The core tank ends below it.

I think it's likely that the domes of the side boosters are part of the tank structure and filled with propellant. For example the space shuttle external tank's nose was filled with LOX.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/04/2015 05:07 PM
I agree.  But again, if you include the interstage as an integral part the center core, the length of all 3 cores is pretty close.  In fact, if you remove the domes, the booster cores would be shorter.
The interstage protects the upper-stage engine. The core tank ends below it.

I think it's likely that the domes of the side boosters are part of the tank structure and filled with propellant. For example the space shuttle external tank's nose was filled with LOX.

No, they won't be - because nose still needs to contain the grid fins + hydraulics, plus the RCS thrusters and propellant.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/04/2015 05:43 PM
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks.
I thought it was 3 for each booster and 3 for the center core, but I'm not sure.  Anyone have a reference?

So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/04/2015 05:49 PM
So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.

3 from each booster was the speculation for Falcon 9 1.0 because 3 were accessible from each side.

With the new arrangement the speculation for 4 engines each came up. But as far as I know it was never more than speculation.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 03/04/2015 06:01 PM
If they can throttle the new upgraded engines, cross feed might not be necessary.  Throttle down the core and throttle up the boosters.  The second stage engine has/is being upgraded also, and it seems to be a much more powerful upgrade. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 03/04/2015 07:08 PM
Still, if you use cross-feed and run all engines @ WOT, you have less gravity losses. The question then becomes whether the LV and the payload can take the G-load.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/04/2015 08:54 PM
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks.
I thought it was 3 for each booster and 3 for the center core, but I'm not sure.  Anyone have a reference?

So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.


I've seen wind generator towers transported on two-lane roads as one unit.  They are typically 212 feet in length. 
https://www.wind-watch.org/faq-size.php (https://www.wind-watch.org/faq-size.php)


The extended side booster of the Falcon Heavy doesn't look like it's much longer than 150 feet, so the length concerns posted here are simply not realistic.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 03/05/2015 12:37 AM


Maybe all three are stretched from v1.1.

From the SpaceX website:

http://www.spacex.com/falcon9
Height 68.4 m 224.4 ft

http://www.spacex.com/falcon-heavy
Height 68.4 m 224.4 ft

If you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MATTBLAK on 03/05/2015 12:44 AM
If they can throttle the new upgraded engines, cross feed might not be necessary.  Throttle down the core and throttle up the boosters.  The second stage engine has/is being upgraded also, and it seems to be a much more powerful upgrade. 

Does anyone know any details about upper stage engine upgrades?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 03/05/2015 01:11 AM
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks.
I thought it was 3 for each booster and 3 for the center core, but I'm not sure.  Anyone have a reference?

So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.


I've seen wind generator towers transported on two-lane roads as one unit.  They are typically 212 feet in length. 
https://www.wind-watch.org/faq-size.php (https://www.wind-watch.org/faq-size.php)


The extended side booster of the Falcon Heavy doesn't look like it's much longer than 150 feet, so the length concerns posted here are simply not realistic.
Nobody said that 120' was an absolute limit for road transport.  Just that the number of possible routes drops off a cliff once you pass 120'.  It doesn't matter whether you can transport 220' towers *somewhere*.  The issues is the maximum load length possible on coast-to-coast routes between Hawthorne, McGregor, and the Cape.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/05/2015 01:14 AM
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate on 03/05/2015 01:22 AM
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.
Turns are probably less of a big deal than height problems.  Slap a 300' cargo a lot of different places in the interstate system (we call them 'hills') and your wheels will be off the ground while the center of the cargo see-saws.  Raise this cargo high up enough that it can survive a gentle hill, and you start to scrape overhead bridges.  Put in dynamic shocks so you can raise or lower it, and even then you can't deal with a deliberate depression under a bridge.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Herb Schaltegger on 03/05/2015 01:43 AM
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.

On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: darkenfast on 03/05/2015 02:06 AM
Something to remember is that there are different levels of oversized.  There is oversized with a permit that can travel night and day and does not require escort vehicles.  Then there is the kind that DOES require escort and can only travel certain hours.  I don't know the details, but there must be a huge difference in cost and time involved.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/05/2015 02:13 AM
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.

On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.
How often would that be necessary?

Anyway, this is all a good argument for Return to Launch Site.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/05/2015 02:19 AM
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled.  Unless there are major obstacles right outside the front gates of either Hawthorne, McGregor (which is a pretty wide open space, so not likely there) or Cape Canaveral, I doubt there will be any on the interstate route in between.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BobHk on 03/05/2015 04:14 AM
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled.  Unless there are major obstacles right outside the front gates of either Hawthorne, McGregor (which is a pretty wide open space, so not likely there) or Cape Canaveral, I doubt there will be any on the interstate route in between.

They look kinda like this:

https://i.imgur.com/3YZfnNg.jpg (https://i.imgur.com/3YZfnNg.jpg)

And this:

http://www.spacex.com/files/assets/img/122908-oversized.jpg (http://www.spacex.com/files/assets/img/122908-oversized.jpg)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 03/05/2015 07:19 AM


Something to remember is that there are different levels of oversized.  There is oversized with a permit that can travel night and day and does not require escort vehicles.  Then there is the kind that DOES require escort and can only travel certain hours.  I don't know the details, but there must be a huge difference in cost and time involved.

F9 v1.0 was sized at the maximum to be transported with minimum fuss. By implication, the constraints on v1.1 transport must be greater.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/05/2015 10:27 AM
If you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies.

Is a second stage stretch confirmed?

Some have speculated that the added 10% volume can be done without a stretch.

For example:
http://forum.nasaspaceflight.com/index.php?topic=36815.msg1340204#msg1340204
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/05/2015 10:30 AM
It doesn't matter whether you can transport 220' towers *somewhere*.  The issues is the maximum load length possible on coast-to-coast routes between Hawthorne, McGregor, and the Cape.
and to the new Boca Chica launch site.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/05/2015 11:19 AM
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled... 

From the link you provided earlier:
https://www.wind-watch.org/faq-size.php

Quote
How are the wind turbine components transported?

Transport of such large items and the cranes needed to assemble them often presents problems in the remote areas where they are typically built. Roads must be widened, curves straightened, and in wild areas new roads built altogether.

So it appears that, while there's no fixed limit, longer stages would tend to present more issues with road transport.

In any case, an informative discussion.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deruch on 03/05/2015 11:23 AM
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled.  Unless there are major obstacles right outside the front gates of either Hawthorne, McGregor (which is a pretty wide open space, so not likely there) or Cape Canaveral, I doubt there will be any on the interstate route in between.

And what is the diameter of the long towers?  Can they be transported off the ground enough that they aren't going to get high centered?  or pinch when spanning dips?  ISTM that it isn't just one dimension in isolation, it may be  the combination that causes the problems.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Herb Schaltegger on 03/05/2015 11:56 AM
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.

On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.
How often would that be necessary?

Anyway, this is all a good argument for Return to Launch Site.

Beats the bejesus out of me. I'm just pointing out that very few interchanges on the U.S. interstate highway system exist where the transitions from surface streets to the highway consist of long, flowing curves and straight stretches. The vast majority have inconvenient right-angle interchanges with stop lights and such at the top/bottom of the ramps. Pull up your favorite mapping website or good old fashioned Rand-McNally and check the routes yourself.

Furthermore, once you're on those surface streets between the nearest interstate and the launch processing site, you still have the same intersection problem. There's a reason why the interstate trucking industry has a pretty much standardizws set of trailer lengths.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/05/2015 12:45 PM
If you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies.

Is a second stage stretch confirmed?

Some have speculated that the added 10% volume can be done without a stretch.

For example:
http://forum.nasaspaceflight.com/index.php?topic=36815.msg1340204#msg1340204
All I see in that post is a clear indication of a stage becoming longer with time.
+10% vol means stretched, period.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/05/2015 01:06 PM
If you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies.

Is a second stage stretch confirmed?

Some have speculated that the added 10% volume can be done without a stretch.

For example:
http://forum.nasaspaceflight.com/index.php?topic=36815.msg1340204#msg1340204
All I see in that post is a clear indication of a stage becoming longer with time.
+10% vol means stretched, period.

Did you read the post?  I'll quote it here:

Quote
Actually, upper stage tank volume +10% does not necessarily mean the outer structure needs to be stretched. A good example is the good old Ariane 4 - its LH2 third stage was modified twice in history (first flight 1988, first modification in 1992 and the second in 1994) to allow for slight increases in the fuel capacity with just internal tank stretches of inches. Each stretch brought about 100-150 kg increase in GTO payload capacity.

(bold mine)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kabloona on 03/05/2015 01:13 PM
Yes, but the graphic shows that the first two stretches did, in fact, grow the overall length of the stage.

Only the final stretch maintained the same stage length, by tweaking the tanks and skirt lengths by a few centimeters.

The scale of the tank growth anticipated on F9 is more consistent with the first two stretches shown in the diagram, both of which increased stage length.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/05/2015 01:26 PM
Yes, but the graphic shows that the first two stretches did, in fact, grow the overall length of the stage.

Only the final stretch maintained the same stage length, by tweaking the tanks and skirt lengths by a few centimeters.

The scale of the tank growth anticipated on F9 is more consistent with the first two stretches shown in the diagram, both of which increased stage length.

To be clear, I'm not trying to argue that the second stage won't be stretched, I'm just trying to figure out if we've confirmed this definitively, or if this is speculation based on certain assumptions.

Who knows what tricks SpaceX has up their sleeve?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kabloona on 03/05/2015 01:46 PM
No confirmation that I've seen.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/05/2015 01:49 PM
No confirmation that I've seen.

You mean confirmation besides Elon Musk saying it in a Twitter?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kabloona on 03/05/2015 01:58 PM
No confirmation that I've seen.

You mean confirmation besides Elon Musk saying it in a Twitter?

Sigh. Yes, we know Elon has tweeted that tank volume  will increase by 10%. That's why we're having this discussion.

The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it might not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/05/2015 02:04 PM
Everything can be imagined or speculated: bulges, external auxiliary tanks, modified pressurization with removal of He COPV tanks etc...
But a one meter stretch of the stage is so simple that "+10% vol" can't mean anything different.

@Dave G
yes I read the post and I saw the figure, showing (as Kabloona said) an ever increasing stage.
Moreover for Falcon 9 there are no "internal tank stretches", the tank is the external structure, therefore tank stretch -> stage stretch.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/05/2015 02:10 PM
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled... 

From the link you provided earlier:
https://www.wind-watch.org/faq-size.php (https://www.wind-watch.org/faq-size.php)

Quote
How are the wind turbine components transported?

Transport of such large items and the cranes needed to assemble them often presents problems in the remote areas where they are typically built. Roads must be widened, curves straightened, and in wild areas new roads built altogether.

So it appears that, while there's no fixed limit, longer stages would tend to present more issues with road transport.

In any case, an informative discussion.


I believe they're talking more about locations such as this:


http://homework.uoregon.edu/pub/class/es202/wind7.jpg (http://homework.uoregon.edu/pub/class/es202/wind7.jpg)


But yeah, there's no doubt that longer stages complicates transport to a certain extent.  However, we're just talking about a fairly minimal stretch for the first stage boosters that's still much less than the maximum that can travel on at least a fair number of public highways.  I think it's less of a problem than some people here are making it out to be.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/05/2015 02:11 PM
Sigh. Yes, we know Elon has tweeted that tank volume  will increase by 10%. That's why we're having this discussion.

The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it will not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.

Sigh indeed. We have a few items we can assume fixed. They will not invent new tooling for the upper stage. They will not reinvent the Merlin vac engine by doing fancy things like a retractable nozzle vac extension.

What is left as a reasonable assumption is a small stretch. Everything else is just fancy imagining, which is nothing new on SpaceX threads. IMO of course.

How long are the second stage tanks, without engine, just the tanks? That gives how much in cm a 10% stretch is.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/05/2015 02:20 PM
How long are the second stage tanks, without engine, just the tanks? That gives how much in cm a 10% stretch is.
About 9 meters, consistently with 90 t propellant load.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deruch on 03/05/2015 02:55 PM
Everything can be imagined or speculated: bulges, external auxiliary tanks, modified pressurization with removal of He COPV tanks etc...
But a one meter stretch of the stage is so simple that "+10% vol" can't mean anything different.
A different meaning that could, hypothetically, be possible:
Chilled LOX gets more "densification gains" than chilled RP-1 (~9% vs. ~5%, respectively), thereby altering the balance of prop:LOX to excess LOX when tanks are full.  Additionally, increased thrust M1d may also have optimum performance with an altered fuel mixture (slightly less LOX). -----> Between higher density and lower fuel mix, less LOX volume is needed.  Current tank sizes are no longer optimized and moving the bulkhead to increase RP-1 tank volume (at the expense of LOX tank volume) re-establishes optimum.  +10% vol (in RP-1 tank) without stage stretch. 

The problem is that Elon announced this all via twitter which really doesn't allow much flexibility for complex/nuanced explanations.  Personally, I think that there is a small stretch, but the above hypothesis could also fit with the currently available public information.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/05/2015 03:46 PM
How long are the second stage tanks, without engine, just the tanks? That gives how much in cm a 10% stretch is.
About 9 meters, consistently with 90 t propellant load.

Thanks. That would translate into 90cm stretch max.  With LOX in the upper tank it would mean the inlet for tanking would need to move by few cm only. That can be done without any modification to the TEL.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/05/2015 04:12 PM
A different meaning that could, hypothetically, be possible:
Chilled LOX gets more "densification gains" than chilled RP-1 (~9% vs. ~5%, respectively), thereby altering the balance of prop:LOX to excess LOX when tanks are full.  Additionally, increased thrust M1d may also have optimum performance with an altered fuel mixture (slightly less LOX). -----> Between higher density and lower fuel mix, less LOX volume is needed.  Current tank sizes are no longer optimized and moving the bulkhead to increase RP-1 tank volume (at the expense of LOX tank volume) re-establishes optimum.  +10% vol (in RP-1 tank) without stage stretch.

The scenario you outline above is quite interesting.  Could be more optimal than a stage stretch.  All things being equal, every pound of additional second stage mass is a pound less max payload.

Yes, a simple stage stretch may be the right answer, but it's interesting to consider other possibilities...


Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 03/05/2015 04:17 PM
Sigh. Yes, we know Elon has tweeted that tank volume  will increase by 10%. That's why we're having this discussion.

The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it might not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.
It has to increase the length.  The stage uses a common bulkhead and is cylindrical.  I doubt there is any room in the interstage for a 10% volume increase.  More thrust needs more propellant to achieve best results, so this stretch seems in line with the up-thrusted engines and with the needs of Falcon Heavy.

 - Ed Kyle 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/05/2015 04:40 PM


Something to remember is that there are different levels of oversized.  There is oversized with a permit that can travel night and day and does not require escort vehicles.  Then there is the kind that DOES require escort and can only travel certain hours.  I don't know the details, but there must be a huge difference in cost and time involved.

F9 v1.0 was sized at the maximum to be transported with minimum fuss. By implication, the constraints on v1.1 transport must be greater.

Cheers, Martin
v1.0 was constrained by width, not length. Or at least there was no indication length was a concern, only width.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/05/2015 05:27 PM


Something to remember is that there are different levels of oversized.  There is oversized with a permit that can travel night and day and does not require escort vehicles.  Then there is the kind that DOES require escort and can only travel certain hours.  I don't know the details, but there must be a huge difference in cost and time involved.

F9 v1.0 was sized at the maximum to be transported with minimum fuss. By implication, the constraints on v1.1 transport must be greater.

Cheers, Martin
v1.0 was constrained by width, not length. Or at least there was no indication length was a concern, only width.


And nowhere other than speculation here have I heard that 1.1 or the FH boosters are any different.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/05/2015 05:54 PM
Sigh. Yes, we know Elon has tweeted that tank volume  will increase by 10%. That's why we're having this discussion.

The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it might not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.
It has to increase the length.  The stage uses a common bulkhead and is cylindrical.  I doubt there is any room in the interstage for a 10% volume increase.  More thrust needs more propellant to achieve best results, so this stretch seems in line with the up-thrusted engines and with the needs of Falcon Heavy.

 - Ed Kyle

hammerhead? the second stage is much smaller and easier to transport, so a small width increase might not cause too many problems.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 03/05/2015 05:58 PM
More thrust needs more propellant to achieve best results...

No it doesn't. You can burn the same volume of prop. at a faster rate and thus have a lesser metric of time x gravity losses. You may have some issues @ MaxQ and MaxDrag, but at other parts of the profile you endure higher G forces in order to induce lower gravity losses. Heck, the MX Peacekeeper missile burns for what, between 1 and 2 minutes before burning out @ almost orbital velocity. Burning the prop in such a short time at very high G means that far more impulse goes into true delta V and much less gravity losses.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/05/2015 06:03 PM
hammerhead? the second stage is much smaller and easier to transport, so a small width increase might not cause too many problems.

And need new tooling for the upper stage. No way this is going to happen. Certainly not for 10% more volume. To be worth it the increase of the upper stage would need to be much bigger.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate on 03/05/2015 06:14 PM
Sigh. Yes, we know Elon has tweeted that tank volume  will increase by 10%. That's why we're having this discussion.

The question is whether that will result in a length increase in the overall stage. I believe it will. Others believe it might not. But no one from SpaceX has confirmed what the actual effect on overall stage length, if any, will be.
It has to increase the length.  The stage uses a common bulkhead and is cylindrical.  I doubt there is any room in the interstage for a 10% volume increase.  More thrust needs more propellant to achieve best results, so this stretch seems in line with the up-thrusted engines and with the needs of Falcon Heavy.

 - Ed Kyle

hammerhead? the second stage is much smaller and easier to transport, so a small width increase might not cause too many problems.
A hammerhead pressure vessel, while not impossible, is relatively novel and incompatible with present production methods - it represents a greater technical risk and greater amount of development than SpaceX has taken with nearly any aspect of their business.  A silly double-F9 upper, with two welded cylinders each holding independent pressure vessels side by side, is more likely than a hammerhead tank, but without an extra orbital stage doubling the dry mass removes most of the benefit.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/05/2015 06:23 PM
SpaceX has a very big Friction Stir Welding machine optimized for a given diameter.
This FSW machine can likely assemble cylindrical sections of any lenght up to the maximum sheet lenght available.
Seems to me that KISS goes for stretching.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BobHk on 03/05/2015 06:32 PM
SpaceX has a very big Friction Stir Welding machine optimized for a given diameter.
This FSW machine can likely assemble cylindrical sections of any lenght up to the maximum sheet lenght available.
Seems to me that KISS goes for stretching.

That would be this guy:
(http://www.spacex.com/files/assets/img/20090922_firststage.jpg)

(http://www.spacex.com/files/assets/img/121208_2ndstgassembly.jpg)

Considering the SpaceX wording of this:
http://www.spacex.com/news/2013/02/12/dragonfalcon-9-update (http://www.spacex.com/news/2013/02/12/dragonfalcon-9-update)
Quote
Note that the first and second stages use a common architecture such as the same 3.7 meter (12 foot) diameter aluminum-lithium barrels and domes, and we manufacture them utilizing the same systems and tooling. This approach greatly reduces overhead, inventory and production costs, and simultaneously contributes to increased reliability. These are essential aspects of how SpaceX improves reliability and lowers the cost of access to space.

A hammerhead seems a lot less likely than a simple stretch of the barrel.  Musk mentioned this machine and its capabilities as a competitive advantage of SpaceX... why make a hammerhead if it makes things more complex when a simple stretch of maybe 90cm will do?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/05/2015 06:48 PM
A hammerhead seems a lot less likely than a simple stretch of the barrel.  Musk mentioned this machine and its capabilities as a competitive advantage of SpaceX... why make a hammerhead if it makes things more complex when a simple stretch of maybe 90cm will do?

Yep...
I must nevertheless point out that pictures you posted are of their old circumferential FSW.
Now SpaceX has a longitudinal FSW that can be seen in the circled area.
Joining of barrels is likely done by electric arc welding in the so called "Paint Booth".
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BobHk on 03/05/2015 07:09 PM
A hammerhead seems a lot less likely than a simple stretch of the barrel.  Musk mentioned this machine and its capabilities as a competitive advantage of SpaceX... why make a hammerhead if it makes things more complex when a simple stretch of maybe 90cm will do?

Yep...
I must nevertheless point out that pictures you posted are of their old circumferential FSW.
Now SpaceX has a longitudinal FSW that can be seen in the circled area.
Joining of barrels is likely done by electric arc welding in the so called "Paint Booth".

I've never seen a arc welding system in a paint booth...

RelyonUsa (http://relyonusa.com/media.php#prettyPhoto)
Quote
SpaceX used a Garmat USA spray booth that was designed, manufactured, and installed through RelyOn Technologies. This spray booth system was design to finish the outer aesthetics and protective layers of their Falcon 9 v1.1 Rocket, which is also known as the Grasshopper. After receiving an initial concept of what the rocket scientists at SpaceX needed, RelyOn was able design a paint booth that was specific to their needs. These types of rockets require external coatings that are equipped for harsh atmospheres.

And if they can do horizontal and circumferential FSW why would they bother to join barrels with arc welding where they don't have to?  Minor welds, fine, but the major join points?  makes no sense.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/05/2015 07:30 PM
In a cylindrical tank, longitudinal stress is half than circumferential.
Therefore best welding system is left to produce long barrels.
Advantage of arc welding is minimal machinery and great flexibility.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 03/05/2015 08:03 PM
v1.0 was constrained by width, not length. Or at least there was no indication length was a concern, only width.
And nowhere other than speculation here have I heard that 1.1 or the FH boosters are any different.
From http://shitelonsays.com/transcript/spacex-dragon-2-unveil-qa-2014-05-29, talking about F9 v1.1:
Quote
It's a nice shot, it's a tall rocket. It's as skinny as I thought we could possibly make it. We stretched to it as long as .. [is that for road transport?] Yeah. It's twelve feet in diameter and when you add little bits and pieces, it gets out to almost 14 feet, and then we have to tuck the little bits and pieces in the corners because the key thing is that the total height above the road has got to be less than 14.5 feet. [Question about bigger rockets.] Need a boat. Or they've got to fly themselves. Not going to fit on the roads, that's for sure.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/06/2015 01:16 AM
v1.0 was constrained by width, not length. Or at least there was no indication length was a concern, only width.
And nowhere other than speculation here have I heard that 1.1 or the FH boosters are any different.
From http://shitelonsays.com/transcript/spacex-dragon-2-unveil-qa-2014-05-29 (http://shitelonsays.com/transcript/spacex-dragon-2-unveil-qa-2014-05-29), talking about F9 v1.1:
Quote
It's a nice shot, it's a tall rocket. It's as skinny as I thought we could possibly make it. We stretched to it as long as .. [is that for road transport?] Yeah. It's twelve feet in diameter and when you add little bits and pieces, it gets out to almost 14 feet, and then we have to tuck the little bits and pieces in the corners because the key thing is that the total height above the road has got to be less than 14.5 feet. [Question about bigger rockets.] Need a boat. Or they've got to fly themselves. Not going to fit on the roads, that's for sure.


Looks to me like he's talking about width as the hard and fast limit.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 03/06/2015 01:28 AM
More thrust needs more propellant to achieve best results...

No it doesn't. You can burn the same volume of prop. at a faster rate and thus have a lesser metric of time x gravity losses. You may have some issues @ MaxQ and MaxDrag, but at other parts of the profile you endure higher G forces in order to induce lower gravity losses. Heck, the MX Peacekeeper missile burns for what, between 1 and 2 minutes before burning out @ almost orbital velocity. Burning the prop in such a short time at very high G means that far more impulse goes into true delta V and much less gravity losses.
But Falcon 9 can't burn its propellant at very high G.  It is already G-limited on purpose to give the payload a soft ride, requiring those fancy Merlins to throttle down after the early phases of flight.  Thrust costs money, and usually adds weight, so it is wasted on a rocket like this unless it allows more propellant to be carried, which allows more payload (or frees up more propellant for recovery burns).

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/06/2015 01:30 AM
The earliest portions of flight have the highest gravity losses. Even if you're acceleration limited, it makes a LOT of sense to get more powerful engines. It also allows better engine-out capability.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Mariusuiram on 03/06/2015 04:20 AM
So much disagreement in all the discussion topics today.

Can we all agree that Elon's "10% increase in 2nd stage vol" will involve a stretch of the 2nd stage between 0 and 10%, so 0 to 90 cm? Some agreement could be therapeutic!  ;D
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/06/2015 11:39 AM
Looks to me like he's talking about width as the hard and fast limit.

No.  Width can be much more.  Up to 33 feet with special permits.

Height is the hard limit.  14.5 feet is the max to get under bridges, power lines, etc.

Length is also limiting, but that's not a hard limit.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Nomadd on 03/06/2015 11:56 AM
Looks to me like he's talking about width as the hard and fast limit.

No.  Width can be much more.  Up to 33 feet with special permits.

Height is the hard limit.  14.5 feet is the max to get under bridges, power lines, etc.

Length is also limiting, but that's not a hard limit.
Anything above about 13.5' greatly reduces the routes you can take. We tried for weeks to plot a route for a 14' 3" trailer from Edison, New Jersey to Portland, Maine and never did find a way. Interstate bridges don't always meet interstate standards.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/06/2015 12:00 PM
Some agreement could be therapeutic!

I see it just the opposite.  Exploring different possibilities often adds information to the discussion.

Yes, a simple stage stretch is quite possible, but if they could somehow add propellant without a stretch, as suggested in Post #217 (http://forum.nasaspaceflight.com/index.php?topic=36806.msg1342024#msg1342024), that would save a lot of mass, increasing the max payload.

Question: On the current Falcon second stage, what is the shape of the bulkhead between the RP-1 and LOX tanks?  Is it a single dome, or a double dome?  Is there any unused space in that area?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cambrianera on 03/06/2015 12:16 PM
Common bulkhead, no unused space.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: ggr on 03/06/2015 02:39 PM
Looks to me like he's talking about width as the hard and fast limit.

No.  Width can be much more.  Up to 33 feet with special permits.

Height is the hard limit.  14.5 feet is the max to get under bridges, power lines, etc.

Length is also limiting, but that's not a hard limit.

Elliptical cross section? Probably not, internal pressure would cause it to deform towards circular anyway, but maybe just for trucking.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 03/06/2015 03:43 PM
Elliptical cross section?.....maybe just for trucking.

No, not possible.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Confusador on 03/06/2015 05:21 PM
Looks to me like he's talking about width as the hard and fast limit.

No.  Width can be much more.  Up to 33 feet with special permits.

Height is the hard limit.  14.5 feet is the max to get under bridges, power lines, etc.

Length is also limiting, but that's not a hard limit.

I think you're saying the same thing... the vehicle *width* was chosen so that when turned sideways for transport it would not exceed the *height* limit.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/06/2015 08:55 PM
It's a round cross section.  Height and width will be the same, not counting trailer elevation, of course.  I should have said "diameter" in the first place.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 03/07/2015 06:03 AM


Everything can be imagined or speculated: bulges, external auxiliary tanks, modified pressurization with removal of He COPV tanks etc...
But a one meter stretch of the stage is so simple that "+10% vol" can't mean anything different.
A different meaning that could, hypothetically, be possible:
Chilled LOX gets more "densification gains" than chilled RP-1 (~9% vs. ~5%, respectively), thereby altering the balance of prop:LOX to excess LOX when tanks are full.  Additionally, increased thrust M1d may also have optimum performance with an altered fuel mixture (slightly less LOX). -----> Between higher density and lower fuel mix, less LOX volume is needed.  Current tank sizes are no longer optimized and moving the bulkhead to increase RP-1 tank volume (at the expense of LOX tank volume) re-establishes optimum.  +10% vol (in RP-1 tank) without stage stretch. 

The problem is that Elon announced this all via twitter which really doesn't allow much flexibility for complex/nuanced explanations.  Personally, I think that there is a small stretch, but the above hypothesis could also fit with the currently available public information.

Speaking of which, Elon did not actually mention RP1 cooling in his tweet, even though it was much shorter than 140 chars :-

Elon Musk (elonmusk):
Upgrades in the works to allow landing for geo missions: thrust +15%, deep cryo oxygen, upper stage tank vol +10%

http://twitter.com/elonmusk/status/572257004938403840

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oldAtlas_Eguy on 03/08/2015 02:34 PM
For FH the increased thrust M1D+ and 10% tank stretch for US implies the following FH payload capabilities increase is possible based on maintaining a constant PMF (propellant mass fraction) for the US by increasing the payload weight and increase the US dry weight for the tank stretch:

FH Trajectory   M1D and current US: Max Payload   M1D+ and 10%> US: Max Payload
LEO   53   58.4
TMI   13.2   14.62
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/08/2015 02:38 PM
Nah, F9 can do >15t to ISS (52deg, 400km) according to the NASA tool: http://elvperf.ksc.nasa.gov/Pages/Query.aspx

As Shotwell has said, for the figures on SpaceX's website, some performance is being withheld for reuse.

Edit: Nevermind, I thought your tmi figures were referring to f9!

But I will say that SpaceX may have been including some of these performance increases already for the 53t figure.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: edkyle99 on 03/08/2015 03:11 PM
For FH the increased thrust M1D+ and 10% tank stretch for US implies the following FH payload capabilities increase is possible based on maintaining a constant PMF (propellant mass fraction) for the US by increasing the payload weight and increase the US dry weight for the tank stretch:

FH Trajectory   M1D and current US: Max Payload   M1D+ and 10%> US: Max Payload
LEO   53   58.4
TMI   13.2   14.62

This assumes that the long-stated 53 tonne goal was achievable using the current length stage.  That is something I've always doubted.  It could be that the stretch is needed to achieve, or approach, that goal.

 - Ed Kyle
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 03/08/2015 07:47 PM
Do you guys think they might add two more boosters for a 4 booster super heavy like the new Russian rocket?  If they did would this get about 75 tons to LEO?  Probably two small a diameter for a good payload. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/08/2015 07:51 PM
If I took a sip of beer every time that has been suggested, I'd be dead of alcohol poisoning.

No, Falcon Heavy is it. No more cores than 3. Even BFR is now back down to a single core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: woods170 on 03/08/2015 07:51 PM
For FH the increased thrust M1D+ and 10% tank stretch for US implies the following FH payload capabilities increase is possible based on maintaining a constant PMF (propellant mass fraction) for the US by increasing the payload weight and increase the US dry weight for the tank stretch:

FH Trajectory   M1D and current US: Max Payload   M1D+ and 10%> US: Max Payload
LEO   53   58.4
TMI   13.2   14.62

This assumes that the long-stated 53 tonne goal was achievable using the current length stage.  That is something I've always doubted.  It could be that the stretch is needed to achieve, or approach, that goal.

 - Ed Kyle
The stretch is in order to come near the performance goal, without the need to develop cross-feed. Cross-feed adds complexity and actually is considered by SpaceX engineers to be an obstacle to rapid first stage reusability.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 03/08/2015 08:01 PM
This assumes that the long-stated 53 tonne goal was achievable using the current length stage.  That is something I've always doubted.  It could be that the stretch is needed to achieve, or approach, that goal.

We don't always agree, but in this case I was thinking the same thing.

And there is precedence for this with the Falcon 9, where SpaceX was selling the V1.1 capability far in advance of fielding the V1.1.  We in the public could only see the V1.0 at the time, but the customer SpaceX was talking with could see the future roadmap.

So for the Falcon Heavy it could be that the 53mT to LEO advertised capability was assuming future upgrades, and we're just now seeing what those upgrades are (or at least part of them).

And there would nothing nefarious about SpaceX not revealing every single detail about their product roadmap, and if they did then we wouldn't have the need to visit NSF and debate anything...   ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Roy_H on 03/08/2015 09:01 PM
The stretch is in order to come near the performance goal, without the need to develop cross-feed. Cross-feed adds complexity and actually is considered by SpaceX engineers to be an obstacle to rapid first stage reusability.

Really? Source? Cross-feed means the side boosters are used up early, and require less fuel to return to launch site. Center core will then most likely land down-range on barge or island (if launched from Texas) and again require less fuel than all three staging close to one another (I know non-crossfeed saves fuel by throttling down center core but still how much fuel does that save?).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wannamoonbase on 03/08/2015 09:12 PM
I'm a big fan of the upgrade, especially on the US. 

I hope that means we eventually see attempts to recover the US on the FH.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 03/17/2015 05:22 PM
https://twitter.com/jeff_foust/status/577878260949864448

Quote
Shotwell: Falcon Heavy side booster will be the same as the enhanced F9 v1.1 to be introduced later this year.

So Gwynne Shotwell confirmed what was read out of the animation video. The side boosters are not longer than the central core any more.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 03/17/2015 05:31 PM
https://twitter.com/jeff_foust/status/577878260949864448

Quote
Shotwell: Falcon Heavy side booster will be the same as the enhanced F9 v1.1 to be introduced later this year.

So Gwynne Shotwell confirmed what was read out of the animation video. The side boosters are not longer than the central core any more.

I agree with you, but in the interests of suppressing a tedious rehashing of this contentious topic, let's note that 140 characters is not *quite* enough to unambiguously confirm your interpretation.  They could be "the same as the enhanced F9"... except for a tank stretch.

Let's all hold off on debating this to death and wait until we see pictures of the hardware.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Semmel on 03/17/2015 06:48 PM
Yeah, lets wait and see. Other question: I see lots of tweets and articles citing Shotwell in the last days. Where is all the info coming from? Was there an event I missed?

Edit:
Awww balls... "Satshow" does not mean "Thats how" in some odd twisted way but "Sat show".. darn.. all right. If there is an interview, I would love to see the transcript..
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 03/17/2015 07:22 PM
https://twitter.com/jeff_foust/status/577878260949864448

Quote
Shotwell: Falcon Heavy side booster will be the same as the enhanced F9 v1.1 to be introduced later this year.

So Gwynne Shotwell confirmed what was read out of the animation video. The side boosters are not longer than the central core any more.

I agree with you, but in the interests of suppressing a tedious rehashing of this contentious topic, let's note that 140 characters is not *quite* enough to unambiguously confirm your interpretation.  They could be "the same as the enhanced F9"... except for a tank stretch.

Let's all hold off on debating this to death and wait until we see pictures of the hardware.
But then we know they'll have uprated Merlin, densified propellant and 10% bigger upper stage, right?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GreenShrike on 03/17/2015 08:31 PM
I agree with you, but in the interests of suppressing a tedious rehashing of this contentious topic, let's note that 140 characters is not *quite* enough to unambiguously confirm your interpretation.  They could be "the same as the enhanced F9"... except for a tank stretch.
But then we know they'll have uprated Merlin, densified propellant and 10% bigger upper stage, right?

I think there's also the question of what they're doing with the oxidizer/fuel ratio.

Densified LOX gets around 10% more mass, but densified RP-1 is more like 5% -- and that's assuming they're chilling the RP-1 as well. As such, to maintain their current O/F ratio they'll need more RP-1, but how?

Are they moving the common bulkhead to shrink the LOX volume and expand the RP-1 tank? Perhaps adjusting the O/F ratio to put more LOX through the engines? Possibly just running the LOX tank a bit empty?

Or maybe they're stretching S1 a smidgen to get more RP-1 volume?

The Falcon 9 already has a very high fineness ratio, but it was designed prior to SpaceX launching 10+ missions, thereby gaining a good deal of  experience flying a high fineness ratio rocket and gathering a lot of data about its in-flight performance and stresses.

If they're stretching S2, with the inherent TEL modifications that entails, perhaps SpaceX feels confident enough to stretch S1 slightly while they're at it.

Perhaps it's not so much a case of the FH's side boosters shrinking to the central core/F9 S1's size, but the "enhanced F9 v1.1" growing to match the FH booster size.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Brovane on 03/17/2015 11:20 PM
Looks to me like he's talking about width as the hard and fast limit.

No.  Width can be much more.  Up to 33 feet with special permits.

Height is the hard limit.  14.5 feet is the max to get under bridges, power lines, etc.

Length is also limiting, but that's not a hard limit.
Anything above about 13.5' greatly reduces the routes you can take. We tried for weeks to plot a route for a 14' 3" trailer from Edison, New Jersey to Portland, Maine and never did find a way. Interstate bridges don't always meet interstate standards.

SpaceX could have very easily plotted the route from Hawthorne to Vanderberg, McGregor and Cape Canaveral and then decided based on limits what the core size is.  I bet they even drove the planned routes to measure exactly what the bridge heights were.  It isn't like they have a wide range of destinations for these cores and have to plan routes all across the nation. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/17/2015 11:29 PM
And there is precedence for this with the Falcon 9, where SpaceX was selling the V1.1 capability far in advance of fielding the V1.1.

Yeah, that's called lying.  Or false advertising.  The problem is they were stating it as Falcon 9 performance, not future-enhancement-version performance (v1.1).  It was widely believed that that was the performance of the original Falcon 9.
Either it's lying, or really awful systems analysis.  Maybe this has been one of the problems with certification.....
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/17/2015 11:32 PM
And there is precedence for this with the Falcon 9, where SpaceX was selling the V1.1 capability far in advance of fielding the V1.1.

Yeah, that's called lying.  Or false advertising.  The problem is they were stating it as Falcon 9 performance, not future-enhancement-version performance (v1.1).  It was widely believed that that was the performance of the original Falcon 9.
Either it's lying, or really awful systems analysis.  Maybe this has been one of the problems with certification.....

No, those numbers were always for a "Block II" F9, it was common knowledge. The Block II morphed into the v1.1. Future capabilities are frequently advertised, because the lead up from order to launch of most payloads is measured in YEARS.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/17/2015 11:37 PM
No, those numbers were always for a "Block II" F9, it was common knowledge. The Block II morphed into the v1.1. Future capabilities are frequently advertised, because the lead up from order to launch of most payloads is measured in YEARS.
Nice try.
I have the original pamphlet they were handing out at the 1st Space Symposium they attended.  It has Falcon 9 performance numbers on it.  No mention of any Block II.  The numbers are off by 30 to 40%.
So where was the actual Falcon 9 1.0 performance ever quoted???
Wouldn't the original pictures of the Falcon Heavy reflect the longer booster(s)?  If they knew that was never going to fly they would have showed the enhanced version with longer cores and upper stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Brovane on 03/17/2015 11:54 PM
No, those numbers were always for a "Block II" F9, it was common knowledge. The Block II morphed into the v1.1. Future capabilities are frequently advertised, because the lead up from order to launch of most payloads is measured in YEARS.
Nice try.
I have the original pamphlet they were handing out at the 1st Space Symposium they attended.  It has Falcon 9 performance numbers on it.  No mention of any Block II.  The numbers are off by 30 to 40%.
So where was the actual Falcon 9 1.0 performance ever quoted???
Wouldn't the original pictures of the Falcon Heavy reflect the longer booster(s)?  If they knew that was never going to fly they would have showed the enhanced version with longer cores and upper stage.

Did you ever sit down and try to buy Falcon 9 launch services?  No?  Then you don't know what numbers were actually disclosed during the negotiations with actual customers before contracts were signed.  Based on SpaceX  lack of flight experience early in the companies history, I have no doubt some early performance numbers were off that had been made public.  What is important is what SpaceX and the customers of it's launch services agreed to in regards to performance that was in the contract not what was printed in some pamphlet. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/17/2015 11:55 PM
No, those numbers were always for a "Block II" F9, it was common knowledge. The Block II morphed into the v1.1. Future capabilities are frequently advertised, because the lead up from order to launch of most payloads is measured in YEARS.
Nice try.
I have the original pamphlet they were handing out at the 1st Space Symposium they attended.  It has Falcon 9 performance numbers on it.  No mention of any Block II.  The numbers are off by 30 to 40%.
So where was the actual Falcon 9 1.0 performance ever quoted???
Wouldn't the original pictures of the Falcon Heavy reflect the longer booster(s)?  If they knew that was never going to fly they would have showed the enhanced version with longer cores and upper stage.

I'm not trying anything, Just stating the obvious.  :D Or do you think that you just uncover a grand conspiracy that I'm trying to hush up?   :o  The original F9 did not end up reaching the performance they targeted. So they improved it.

As for the pamphlet, it's called marketing.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 12:14 AM
The original F9 did not end up reaching the performance they targeted.


But that's my "issue".  Did they not reach the performance because of poor analysis?  Weight came in much heavier? 

It clearly shows a short Falcon 9, the 3x3 engine configuration, thrust and ISP for the propulsion (1C).
And then the performance numbers are for another rocket that will be flying 5 years later??   I just don't buy it. But that's my opinion.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 03/18/2015 12:53 AM
The original F9 did not end up reaching the performance they targeted.


But that's my "issue".  Did they not reach the performance because of poor analysis?  Weight came in much heavier? 

It clearly shows a short Falcon 9, the 3x3 engine configuration, thrust and ISP for the propulsion (1C).
And then the performance numbers are for another rocket that will be flying 5 years later??   I just don't buy it. But that's my opinion.


Which is worth how much?  Are you threatening to sue SpaceX?  Are you trying to drum up popular opposition?  Are you trying to be a whistleblower?


The business relationships, and whatever agreements are reached, between SpaceX and its clients are exactly between them -- not us.  Indignation serves you no purpose.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: watermod on 03/18/2015 12:57 AM
If you watched the Air Force side of the House hearing today they were lamenting that SpaceX was not having earlier test launches of the Heavy.  They are looking at a 2 year gap because they the gov. will not start designing a payload for a heavy until after it is certified.   They doubted they could get it certified until 2019-20 which meant no launches until 2022.
ULA is playing hardball with their Delta IV Heavy saying they can't afford to launch it for less than a billion $ if they have to shut down their Atlas line waiting for a new engine.   Also they plan on shutting down the regular Delta 4medium as it can't compete against the Falcon 9.   

It's an interesting game of holding breath until somebody turns blue or calls out uncle.   Lots of talk about SpaceX being a monopoly government launcher in the gap period.   That's kind of choice as the block buy and current non-certified F-9 means SpaceX is currently not an Air Force EELV supplier just desires to be one so calling them the future monopoly looks like fear mongering.

No willingness on the Air Force side to do concurrent design of pieces.   Why can't one design the payloads without the launcher and just have an adapter standard for the launchers that will be the same for all Air Force heavy payloads?  Then you really wouldn't care if it was a Delta 4, a Falcon Heavy or anything else that built to the interface.   It just seems nuts to wait until certification to design the payload, but then I have never done large government engineering projects, just large commercial non-rocket ones with multiple risky points (some with 3 or more may the best man win alternatives for the risk points).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 01:10 AM

Which is worth how much?  Are you threatening to sue SpaceX?  Are you trying to drum up popular opposition?  Are you trying to be a whistleblower?

The business relationships, and whatever agreements are reached, between SpaceX and its clients are exactly between them -- not us.  Indignation serves you no purpose.

Don't understand the 1st question.
No.  Sue for what?  Lying?
No.  Trying to understand why they wouldn't be honest.  If the "real" performance is kept behind closed doors, then why advertise anything?  Why have a website?  Why boast about capability in public? Why tweet?
I never claimed anything illegal.  Not sure what whistleblowing would do or even who to inform of what.

I also never claimed their agreements or contracts should be public.   I never asked for any information from SpaceX.  Everything I have is from their own advertising and their website.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 03/18/2015 01:19 AM
And there is precedence for this with the Falcon 9, where SpaceX was selling the V1.1 capability far in advance of fielding the V1.1.

Yeah, that's called lying.  Or false advertising.  The problem is they were stating it as Falcon 9 performance, not future-enhancement-version performance (v1.1).  It was widely believed that that was the performance of the original Falcon 9.
Either it's lying, or really awful systems analysis.  Maybe this has been one of the problems with certification.....

Yeah, that's called "They didn't tell me".

So far, it's been clear that REAL customers were privy to the performance and upgrade information well in advance of the general public and you.  All payloads have ended up in their prescribed orbits, so I guess performance never fell short of promises.

What's giving you acid is that public information wasn't detailed enough.  First show me a launch company that lists performance and pricing in a neat little table on their public web site, then we can talk about certification.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/18/2015 01:22 AM
So... SpaceX deliberately misled the public by publicizing a slightly better version of F9 v1.0 but INSTEAD giving us a rocket with nearly twice v1.0's performance. I know, I know, it's HORRIBLE, but true!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 01:30 AM

All payloads have ended up in their prescribed orbits, so I guess performance never fell short of promises.

What's giving you acid is that public information wasn't detailed enough.  First show me a launch company that lists performance and pricing in a neat little table on their public web site, then we can talk about certification.

You mean like the Orbcom-OG2 payload?  Why bother upgrade to 1.1 if performance never fell short?
I don't want more detail.   Doesn't ULA have a mission planner's guide that lists performance?   I also never requested ANYTHING about pricing.  All prices are negotiable to some extent.   I really don't want to talk to you about certification.

After browsing through the forum topics, I'm starting to realize this is a SpaceX forum.  It seems like 80 to 90% of all posts are "SpaceX will/can do everything topics"  Even the launch coverage has about a 20 to 1 ratio.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 01:34 AM
So... SpaceX deliberately misled the public by publicizing a slightly better version of F9 v1.0 but INSTEAD giving us a rocket with nearly twice v1.0's performance. I know, I know, it's HORRIBLE, but true!

If it has twice the performance, then initial estimates were off 100%.  So what was v1.0 performance capability?
I never claimed v1.1 didn't live up to it's estimates.  Just that v1.0 didn't come close. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 03/18/2015 01:46 AM

All payloads have ended up in their prescribed orbits, so I guess performance never fell short of promises.

What's giving you acid is that public information wasn't detailed enough.  First show me a launch company that lists performance and pricing in a neat little table on their public web site, then we can talk about certification.

You mean like the Orbcom-OG2 payload?  Why bother upgrade to 1.1 if performance never fell short?
I don't want more detail.   Doesn't ULA have a mission planner's guide that lists performance?   I also never requested ANYTHING about pricing.  All prices are negotiable to some extent.   I really don't want to talk to you about certification.

After browsing through the forum topics, I'm starting to realize this is a SpaceX forum.  It seems like 80 to 90% of all posts are "SpaceX will/can do everything topics"  Even the launch coverage has about a 20 to 1 ratio.

It's cute, because I could see the Orbcom red herring coming even as I was typing my post...  But figured I might as well give you the benefit of the doubt.

So for kicks - what does Orbcomm have to do with anything?  That was an engine-out event, combined with HSF flight safety rules, and absolutely nothing to do with published or actual performance. 

Or is it that they also lied because they didn't write on the website that anomalies happen and the chance for success is <100%
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 01:51 AM
It's cute, because I could see the Orbcom red herring coming even as I was typing my post...  But figured I might as well give you the benefit of the doubt.

So for kicks - what does Orbcomm have to do with anything?  That was an engine-out event, combined with HSF flight safety rules, and absolutely nothing to do with published or actual performance. 

Or is it that they also lied because they didn't write on the website that anomalies happen and the chance for success is <100%

Benefit of what doubt?   I don't understand your question about what they have to do with anything.  If an engine goes out, isn't that losing performance?  (See AV-009)  You're the one who brought up perfect performance and 100% satisfaction.  Everybody has anomalies.  So does ULA.  Why are you so sensitive? 

If you're only using 50% of your capability, you can correct for a lot of performance-related anomalies.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/18/2015 01:58 AM
So... SpaceX deliberately misled the public by publicizing a slightly better version of F9 v1.0 but INSTEAD giving us a rocket with nearly twice v1.0's performance. I know, I know, it's HORRIBLE, but true!

If it has twice the performance, then initial estimates were off 100%.  So what was v1.0 performance capability?
I never claimed v1.1 didn't live up to it's estimates.  Just that v1.0 didn't come close.
Almost all the published figures for v1.0's performance were for block II's performance. They were to do a few block I flights before transitioning to the better block II.

Apparently, they said "hell with it" and just did v1.1, which kept all the promises they made before plus a whole lot more. But just because you weren't careful enough to listen to them telling you that they were (in virtually every case) talking about block II performance (and not block I) doesn't mean that they "lied" about F9's performance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 02:00 AM
Almost all the published figures for v1.0's performance were for block II's performance. They were to do a few block I flights before transitioning to the better block II.

Apparently, they said "hell with it" and just did v1.1, which kept all the promises they made before plus a whole lot more. But just because you weren't careful enough to listen to them telling you that they were (in virtually every case) talking about block II performance (and not block I) doesn't mean that they "lied" about F9's performance.

Thanks for your answer.  So was the capability of  v1.0 ever published then?  Anywhere or anytime?

Falcon 9 first flew in June of 2010.   When did the first information about v1.1's (Block II) come into public.  Was it not until 2012?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/18/2015 02:02 AM
By the time they had detailed specs on their website, they had already filled those first few Falcon 9 block I flights. Anyone who asked for a flight would be given the higher performing version (except perhaps by very special request). Are you suggesting that SpaceX was "lying" just because they decided to give their customers an even more capable rocket?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/18/2015 02:04 AM
Almost all the published figures for v1.0's performance were for block II's performance. They were to do a few block I flights before transitioning to the better block II.

Apparently, they said "hell with it" and just did v1.1, which kept all the promises they made before plus a whole lot more. But just because you weren't careful enough to listen to them telling you that they were (in virtually every case) talking about block II performance (and not block I) doesn't mean that they "lied" about F9's performance.

Thanks for your answer.  So was the capability of  v1.0 ever published then?  Anywhere or anytime?
Yeah, at one point you could see the performance here (just has the newer version now... although actually it might be the upgrade-to-v1.1, but regardless): http://elvperf.ksc.nasa.gov
NASA clearly knew what they were getting.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/18/2015 02:06 AM
Almost all the published figures for v1.0's performance were for block II's performance. They were to do a few block I flights before transitioning to the better block II.

Apparently, they said "hell with it" and just did v1.1, which kept all the promises they made before plus a whole lot more. But just because you weren't careful enough to listen to them telling you that they were (in virtually every case) talking about block II performance (and not block I) doesn't mean that they "lied" about F9's performance.

Thanks for your answer.  So was the capability of  v1.0 ever published then?  Anywhere or anytime?

Falcon 9 first flew in June of 2010.   When did the first information about v1.1's (Block II) come into public.  Was it not until 2012?
v1.1 isn't "block II," actually.

If you look at F9 v1.0's user's guide (the latest version is 2009), it only gives figures for Block II performance, figures that were far exceeded by v1.1.

If you're confused, don't worry, you're not the only one! :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: QuantumG on 03/18/2015 02:07 AM
Couldn't you lot start a splinter thread if you want to talk about all this non-FH stuff?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Newton_V on 03/18/2015 02:07 AM
Are you suggesting that SpaceX was "lying" just because they decided to give their customers an even more capable rocket?

I'm just wondering how they knew the performance of v1.1 in July of 2010, when they were showing performance data for the v1.0.  They must have know it would be a stretched booster and upper stage. 

Anyways, I guess I'm done here.  Thanks for your answers.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Galactic Penguin SST on 03/18/2015 02:10 AM
Hmm....I thought this was more of a PR problem than anything else? If you check the 2008 user manual (their last one) it has both a block I and block II F9 listed.

The problem is that there has been no update since then - I think they are the only major LSP right now that doesn't even have a user manual available (several LSP requires limited access to it, but I don't think SpaceX even has that). Maybe v1.1 has so many frequent changes as much as the Spitfire did that they aren't bothered to make one?

Anyway I think this should be discussed in a new thread - lemme open it right now....  ;)

Edit: New thread is at http://forum.nasaspaceflight.com/index.php?topic=37058.0.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: gongora on 03/18/2015 02:34 AM
If you watched the Air Force side of the House hearing today they were lamenting that SpaceX was not having earlier test launches of the Heavy. ...

I thought the second panel at the hearing was quite complimentary of SpaceX today.  They're just trying to be realistic in figuring out a schedule of launch vehicle availability for the next 7-8 years.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ford Mustang on 03/18/2015 03:33 AM
Couldn't you lot start a splinter thread if you want to talk about all this non-FH stuff?



I'll second that.  Let's jump back on topic, if you'd like to talk about non-Falcon Heavy stuff, feel free to make another thread.  Thanks!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/18/2015 05:46 AM

If you watched the Air Force side of the House hearing today they were lamenting that SpaceX was not having earlier test launches of the Heavy. ...

I thought the second panel at the hearing was quite complimentary of SpaceX today.  They're just trying to be realistic in figuring out a schedule of launch vehicle availability for the next 7-8 years.

I thought so too, they (the AF people) had schedule concerns but also expressed a lot of faith in SpaceX's ability to execute.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: newpylong on 03/18/2015 01:30 PM
Who believes we will see the demo flight this year? I don't think we will.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 03/18/2015 01:37 PM
The Falcon heavy should be shortly after they finish work a the cape.  Once the launch pad and facilities are ready, it should be shortly (1-2 months) probably after that.  I think that is a bigger hold up than the rocket itself. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: newpylong on 03/18/2015 01:43 PM
The Falcon heavy should be shortly after they finish work a the cape.  Once the launch pad and facilities are ready, it should be shortly (1-2 months) probably after that.  I think that is a bigger hold up than the rocket itself.

If the rocket was ready they would just do it from Vandenberg, but it's not. The qualification articles still need to be sent to McGregor. A new vehicle, albeit built on existing cores, is not going to just roll onto the pad for launch.

Not that I see LC-39A being completed this year either.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JamesH on 03/18/2015 01:56 PM
The Falcon heavy should be shortly after they finish work a the cape.  Once the launch pad and facilities are ready, it should be shortly (1-2 months) probably after that.  I think that is a bigger hold up than the rocket itself.

If the rocket was ready they would just do it from Vandenberg, but it's not. The qualification articles still need to be sent to McGregor. A new vehicle, albeit built on existing cores, is not going to just roll onto the pad for launch.

Not that I see LC-39A being completed this year either.

Is it really that simple? Can they just up and move a launch of something like this to Vandenburg, just because the rocket is ready to go? I suspect not.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: abaddon on 03/18/2015 02:40 PM
The rocket must be fully qualified at McGregor before anything can happen.  That hasn't happened yet.  We'll know when it happens.  If 39A isn't ready at that point, we have no idea if Vandenberg would be, and I would guess it probably wouldn't be.  Why would they work to make their VAFB pad FH ready when they could be working on 39A instead?  We know it has some elements of an FH architecture but that doesn't mean it's FH-ready yet.

I am still hoping for the rocket to complete qualification and be shipped to the Cape before end of the calendar year, but I think hoping for it to actually launch on the demo mission by then is unrealistic at this point.  There's still going to be a lot of work on-site to get the thing launched on a new pad, once it does arrive.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 03/18/2015 03:08 PM
Some of the qualification articles have been sent to MacGregor, I believe.  We had reports of at least one core leaving the factory at Hawthorne.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: WindnWar on 03/18/2015 03:59 PM
During the hearing yesterday it was mentioned that in order for the Falcon Heavy to be certified to handle all the payloads the Delta IV Heavy currently handles it would need to direct inject 14,500 kilos of payload into GEO, and then endure a coast phase of 3 hours followed by another burn. Gen. Mitchell stated that the stage to do this doesn't currently exist.

If that is the case, what sort of upgrades would be needed to the second stage to be able to do this or is Gen. Mitchell mistaken? The other question would be how many payloads need this capability? What is the longest coast so far they have done? Would gelling of the RP1 and stage power be the issues?

As pointed out below I mistook pounds for kilos, so it is 14,500 pounds to direct inject. The length of the coast phase is still curious though.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GalacticIntruder on 03/18/2015 04:11 PM
During the hearing yesterday it was mentioned that in order for the Falcon Heavy to be certified to handle all the payloads the Delta IV Heavy currently handles it would need to direct inject 14,500 kilos of payload into GEO, and then endure a coast phase of 3 hours followed by another burn. Gen. Mitchell stated that the stage to do this doesn't currently exist.

If that is the case, what sort of upgrades would be needed to the second stage to be able to do this or is Gen. Mitchell mistaken? The other question would be how many payloads need this capability? What is the longest coast so far they have done? Would gelling of the RP1 and stage power be the issues?

I heard that as well, but think the General is confused. The D4H cannot even do 14mT direct GEO, but can do that to GTO. Can do half of that to GEO, though. The NRO requirements are direct GEO capability. ULA can do it, but SpaceX has not done it, and never even mentions it. Direct GEO is tough and extremely rare, and FH should be capable of that, but has to prove it. SpaceX U/S is not really set up for direct GEO, or high dV missions. Hence the concern of the AF.

Unless there have been classified payloads, almost all payloads are less than 7000kg and go to GTO. But during wartime, they might need a payload operational ASAP, so the NRO says they need to have that option.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: rcoppola on 03/18/2015 04:29 PM
So if this enhanced F9 debuting this summer increases the current cores performance by %30 and that updated core is used for the boosters as has been reported (but there still seems to be a bit of confusion about the center core config) and the second stage is stretched with M1Dvac improvements as well, now what are the true capabilities of the FH?  Are we now talking about 56t to Leo without cross-feed?

What would this beast be able to do completely expendable? I know there's a ton of calcs on this throughout this and other threads but this updated configuration info, albeit incomplete is just now coming in.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: gongora on 03/18/2015 09:14 PM
During the hearing yesterday it was mentioned that in order for the Falcon Heavy to be certified to handle all the payloads the Delta IV Heavy currently handles it would need to direct inject 14,500 kilos of payload into GEO, and then endure a coast phase of 3 hours followed by another burn. Gen. Mitchell stated that the stage to do this doesn't currently exist.

If that is the case, what sort of upgrades would be needed to the second stage to be able to do this or is Gen. Mitchell mistaken? The other question would be how many payloads need this capability? What is the longest coast so far they have done? Would gelling of the RP1 and stage power be the issues?

I heard that as well, but think the General is confused. The D4H cannot even do 14mT direct GEO, but can do that to GTO. Can do half of that to GEO, though. The NRO requirements are direct GEO capability. ULA can do it, but SpaceX has not done it, and never even mentions it. Direct GEO is tough and extremely rare, and FH should be capable of that, but has to prove it. SpaceX U/S is not really set up for direct GEO, or high dV missions. Hence the concern of the AF.

Unless there have been classified payloads, almost all payloads are less than 7000kg and go to GTO. But during wartime, they might need a payload operational ASAP, so the NRO says they need to have that option.

He said 14500 pounds, not kilos.  6.5 metric tons. (remark is at 2:14:10 in hearing video on youtube)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BobHk on 03/18/2015 09:46 PM
During the hearing yesterday it was mentioned that in order for the Falcon Heavy to be certified to handle all the payloads the Delta IV Heavy currently handles it would need to direct inject 14,500 kilos of payload into GEO, and then endure a coast phase of 3 hours followed by another burn. Gen. Mitchell stated that the stage to do this doesn't currently exist.

If that is the case, what sort of upgrades would be needed to the second stage to be able to do this or is Gen. Mitchell mistaken? The other question would be how many payloads need this capability? What is the longest coast so far they have done? Would gelling of the RP1 and stage power be the issues?

I heard that as well, but think the General is confused. The D4H cannot even do 14mT direct GEO, but can do that to GTO. Can do half of that to GEO, though. The NRO requirements are direct GEO capability. ULA can do it, but SpaceX has not done it, and never even mentions it. Direct GEO is tough and extremely rare, and FH should be capable of that, but has to prove it. SpaceX U/S is not really set up for direct GEO, or high dV missions. Hence the concern of the AF.

Unless there have been classified payloads, almost all payloads are less than 7000kg and go to GTO. But during wartime, they might need a payload operational ASAP, so the NRO says they need to have that option.

I have a feeling more birds like NROL-32 (13mT 328foot antenna ELINT) would be up there if they could get more rockets to push them up there...if the cost is lessened by SpaceX FH....

(http://upload.wikimedia.org/wikipedia/commons/9/9e/NROL32_patch.jpg)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/19/2015 11:15 AM
Nah, even at $400 million per launch, the satellite is still a lot more expensive than the rocket.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: fthomassy on 03/19/2015 02:19 PM
I have a feeling more birds like NROL-32 (13mT 328foot antenna ELINT) would be up there if they could get more rockets to push them up there...if the cost is lessened by SpaceX FH....
Is that the real mission patch?  At first I thought it was a joke about the symbolism of expensive rockets burning money. :o
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 03/19/2015 02:33 PM
I have a feeling more birds like NROL-32 (13mT 328foot antenna ELINT) would be up there if they could get more rockets to push them up there...if the cost is lessened by SpaceX FH....
Is that the real mission patch?  At first I thought it was a joke about the symbolism of expensive rockets burning money. :o
The "all-seeing eye" is often used for intelligence sats.  The real question is how it got onto our money. ;)

EDIT: yes, I know how it got onto our money.  I'm just pointing out that it's a more natural fit on the mission patch.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dave G on 03/19/2015 05:09 PM
The "all-seeing eye" is often used for intelligence sats.  The real question is how it got onto our money. ;)
The free masons were mostly religious.  The eye at the top of the pyramid represents god.  The idea is that god can see all 4 sides of the pyramid at once, while humans, from our vantage point, can only see 1 or 2.

Not trying to promote religion or anything, just explain what their thinking was behind the eye on our money.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 03/19/2015 06:42 PM
The "all-seeing eye" is often used for intelligence sats.  The real question is how it got onto our money. ;)
The free masons were mostly religious.  The eye at the top of the pyramid represents god.  The idea is that god can see all 4 sides of the pyramid at once, while humans, from our vantage point, can only see 1 or 2.

Not trying to promote religion or anything, just explain what their thinking was behind the eye on our money.
I always thought there was a pyramid stuck in His eye, because He's just so big. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 03/20/2015 10:14 AM
Just a question: Over on the Falcon 9 v.1.2 thread, it was stated that the projected performance figures for that upgrade were above the published Falcon 9 Block-II figures. If this is the case, will this push Falcon Heavy's performance about 53t IMLEO? Additionally, will the improved Merlin-1d performance in any way affect Merlin-1d-VAC's vacuum ISP?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 03/20/2015 12:49 PM
Just a question: Over on the Falcon 9 v.1.2 thread, it was stated that the projected performance figures for that upgrade were above the published Falcon 9 Block-II figures. If this is the case, will this push Falcon Heavy's performance about 53t IMLEO? Additionally, will the improved Merlin-1d performance in any way affect Merlin-1d-VAC's vacuum ISP?
Falcon Heavy's 53t performance assumed Falcon v1.1 and cross feeding. As I understand it, all this improvements are done to allow Falcon Heavy's performance targets without cross feeding. BTW, I believe the target would be 6tonnes to GSO (expendable) and 6.5tonnes to GTO with full boosters and core reusability. But that's my estimation. It was generally accepted that v1.1 FH without cross-feeding would be about 45tonnes to LEO or so. Thus, all this improvements might allow for closer to 50tonnes OR around 35 tonnes to LEO with the three cores RTLS. And that's where it gets really interesting. Think about it for a potential LEO station, like Bigelow, you can launch 35tonnes to LEO for about (may be even less) than a Falcon 9 expendable flight. Unproven, but if achieved, it would allow for really cheap stations and supply runs. Something like an LM's Jupiter/Exoliner but with a mass of 35 tonnes could probably take 15tonnes per trip, which is all that's currently required for the ISS USOS  :D.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/20/2015 07:52 PM
this was posted to twitter by spacex, then removed within minutes?

associated text was something about "F9H wind tunnel model now decorates the factory".

image URL is: https://pbs.twimg.com/media/CAkSO7OUUAA4-ty.jpg
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: The_Ronin on 03/20/2015 07:56 PM
Tweet and FB post have now been deleted.  I can't tell for sure but it looks like a larger fairing and 2nd stage.  Also confirms that the boosters and core are the same size after all, too.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 03/20/2015 07:56 PM
this was posted to twitter by spacex, then removed within minutes?

associated text was something about "F9H wind tunnel model now decorates the factory".

Look how long the "neck" is on that model!  Is it my imagination, or is the 2nd stage stretched?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Chris Bergin on 03/20/2015 07:59 PM
Shows up in my timeline! Very sexy!!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/20/2015 08:02 PM
larger version..

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: somepitch on 03/20/2015 08:11 PM
I had the same thing with it disappearing... What a gorgeous model though!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/20/2015 08:12 PM
Shows up in my timeline! Very sexy!!

don't close it.. see if you can view the full image for the 'tail shot'...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: jabe on 03/20/2015 08:12 PM
do legs look the same as current ones? thought they would look different ..isn't there a new leg being developed?
jb
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/20/2015 08:13 PM
What probably happened: "Oh, snap, what about ITAR? Has legal seen this yet?"
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: docmordrid on 03/20/2015 08:14 PM
Jeezes....allowing for foreshortening due to the angle, it almost looks like a 5.2x20m long fairing.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/20/2015 08:15 PM
Tweet and FB post have now been deleted.  I can't tell for sure but it looks like a larger fairing and 2nd stage.  Also confirms that the boosters and core are the same size after all, too.

You can't judge try upper stage or fairing length from a picture with this wide angle perspective.


Jeezes....allowing for foreshortening due to the angle, it almost looks like a 5.2x20m long fairing.

Unless you can show your math - don't. Just don't.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: gongora on 03/20/2015 08:17 PM
the other shot
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/20/2015 08:20 PM
larger version of the 'tail shot'
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/20/2015 08:21 PM
the other shot

And anticipating some people now speculating that FH will have 8 engines per core in 3....2...1... Sigh, it is inevitable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: gongora on 03/20/2015 08:23 PM
the other shot

And anticipating some people now speculating that FH will have 8 engines per core in 3....2...1... Sigh, it is inevitable.

and those center core nozzles...  ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/20/2015 08:23 PM
the other shot

And anticipating some people now speculating that FH will have 8 engines per core in 3....2...1... Sigh, it is inevitable.

the center core's eight engines are sliced in half in an odd way, too.. would have thought those changes would make wind tunnel testing a bit off.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: PahTo on 03/20/2015 08:27 PM
the other shot

And anticipating some people now speculating that FH will have 8 engines per core in 3....2...1... Sigh, it is inevitable.

and those center core nozzles...  ;)

Silly, that's the debut of the Raptor!
:)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: J-V on 03/20/2015 08:28 PM
Have the horizontal supports been in the bottom of the stages in previous images? I don't rember seeing them.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Tonioroffo on 03/20/2015 08:34 PM
Man, they should launch it like that, chrome rocket.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Sesquipedalian on 03/20/2015 08:44 PM
Reposted from the General Falcon discussion thread:

I notice that model shows what appeared to be LOX feedlines running down the outside of the stage.  I was wondering why this was the case, as it had been previously established that the LOX feed runs down the center of the kerosene tank, with the tank making a torus shape around it.

But then I realized that by moving the LOX feed to the outside of the rocket, they gain a significant amount of volume on the inside.  This could be a way to accomplish their stated goals of increasing tank capacity without requiring a tank stretch and the cascade of changes that would entail.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco on 03/20/2015 08:50 PM
During the hearing yesterday it was mentioned that in order for the Falcon Heavy to be certified to handle all the payloads the Delta IV Heavy currently handles it would need to direct inject 14,500 kilos of payload into GEO, and then endure a coast phase of 3 hours followed by another burn. Gen. Mitchell stated that the stage to do this doesn't currently exist.

If that is the case, what sort of upgrades would be needed to the second stage to be able to do this or is Gen. Mitchell mistaken? The other question would be how many payloads need this capability? What is the longest coast so far they have done? Would gelling of the RP1 and stage power be the issues?

As pointed out below I mistook pounds for kilos, so it is 14,500 pounds to direct inject. The length of the coast phase is still curious though.
Look here: http://forum.nasaspaceflight.com/index.php?topic=30544.15
STP2 mission discussion.
STP2 mission includes a lot of restarts and coasts. Including a 3-5 hour coast.
So it sounds like a successful STP2 mission would prove the raw components of a direct GEO insertion, although the orbits involved are not GTO/GEO.
I recall Jim stating FH demo launch will execute the STP2 mission. That first FH launch scheduled for 2015 (with a possible slip to 2016).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 03/20/2015 08:53 PM
Reposted from the General Falcon discussion thread:

I notice that model shows what appeared to be LOX feedlines running down the outside of the stage.  I was wondering why this was the case, as it had been previously established that the LOX feed runs down the center of the kerosene tank, with the tank making a torus shape around it.

But then I realized that by moving the LOX feed to the outside of the rocket, they gain a significant amount of volume on the inside.  This could be a way to accomplish their stated goals of increasing tank capacity without requiring a tank stretch and the cascade of changes that would entail.

Is that a LOX feedline?  It looks like it runs the full length of the upper stage.  If a LOX feed line wouldn't it only run from the bottom of the LOX tank down the outside?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Chris Bergin on 03/20/2015 09:10 PM
Oh yeah, gone from my timeline now. Wonder what's going on there? Accidental delete of the tweet? I've done that before! :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jdeshetler on 03/20/2015 09:18 PM
Corrected with Adobe's Perspective Warp.

This revised photo of FH's payload fairing now looks standard to me.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: starsilk on 03/20/2015 09:31 PM
Oh yeah, gone from my timeline now. Wonder what's going on there? Accidental delete of the tweet? I've done that before! :)

disappeared from facebook too.. probably realized they'd run their wind tunnel tests with three engines missing and needed the model back to do it again..  ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: rcoppola on 03/20/2015 09:45 PM
Reposted from the General Falcon discussion thread:

I notice that model shows what appeared to be LOX feedlines running down the outside of the stage.  I was wondering why this was the case, as it had been previously established that the LOX feed runs down the center of the kerosene tank, with the tank making a torus shape around it.

But then I realized that by moving the LOX feed to the outside of the rocket, they gain a significant amount of volume on the inside.  This could be a way to accomplish their stated goals of increasing tank capacity without requiring a tank stretch and the cascade of changes that would entail.

Is that a LOX feedline?  It looks like it runs the full length of the upper stage.  If a LOX feed line wouldn't it only run from the bottom of the LOX tank down the outside?
Hmmm, saw that to and thought 3 things in addition to it being a feedline:

-Part of a new pressurization system
-Part of a new GSE system
-Needed for new chill system
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: newpylong on 03/20/2015 09:59 PM
Beautiful!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: StuffOfInterest on 03/20/2015 10:39 PM
the other shot

And anticipating some people now speculating that FH will have 8 engines per core in 3....2...1... Sigh, it is inevitable.

the center core's eight engines are sliced in half in an odd way, too.. would have thought those changes would make wind tunnel testing a bit off.

Isn't that where the support rod will be inserted? You wouldn't "hang" the model in the wind tunnel or the ropes would throw off the simulation.  You need to support it from directly behind the wind stream to have a minimal impact.

One thing I wonder about is if the rocket plume has any effect on the wind tunnel modeling.  Does the plume act like a solid surface or does it just absorb any flow?  Considering the video showing flame re-circulation from the last night launch I'd home they have a way of modeling how the flow behaves.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MechE31 on 03/21/2015 12:56 AM
Reposted from the General Falcon discussion thread:

I notice that model shows what appeared to be LOX feedlines running down the outside of the stage.  I was wondering why this was the case, as it had been previously established that the LOX feed runs down the center of the kerosene tank, with the tank making a torus shape around it.

But then I realized that by moving the LOX feed to the outside of the rocket, they gain a significant amount of volume on the inside.  This could be a way to accomplish their stated goals of increasing tank capacity without requiring a tank stretch and the cascade of changes that would entail.

Is that a LOX feedline?  It looks like it runs the full length of the upper stage.  If a LOX feed line wouldn't it only run from the bottom of the LOX tank down the outside?
Hmmm, saw that to and thought 3 things in addition to it being a feedline:

-Part of a new pressurization system
-Part of a new GSE system
-Needed for new chill system

Looks pretty much like the existing primary raceway to me...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: gongora on 03/21/2015 01:21 AM
SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 03/21/2015 02:17 AM
Is this the 147,000 lb thrust engine or is it greater than that?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate on 03/21/2015 02:42 AM
SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
The article *also* says:
Quote
In March 16 and 17 appearances at the Satellite 2015 conference here, Shotwell said the new-version Falcon 9, which has yet to be named, will be about 30 percent more powerful than the rocket’s current version.

30%?  Where did 30% come from?

We were told that the M1D engines were certified to 85% design spec before.  A 17.6% increase in existing thrust would bring it to 100% design spec.

Are they going *further* than that?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GalacticIntruder on 03/21/2015 02:43 AM
Is this the 147,000 lb thrust engine or is it greater than that?

You mean this?

Quote
“Falcon Heavy is two different cores — the inner core and the two side sticks,” Shotwell said. “The new Falcon 9 will basically be a Falcon Heavy side booster. So we’re building [only two different] cores to make sure we don’t have a bunch of configurations around the factory so we can streamline operations and hit a launch cadence of one or two a month from every launch site we have.” - See more at: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/#sthash.Kk4wUTpC.dpuf
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GalacticIntruder on 03/21/2015 02:59 AM
SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
The article *also* says:
Quote
In March 16 and 17 appearances at the Satellite 2015 conference here, Shotwell said the new-version Falcon 9, which has yet to be named, will be about 30 percent more powerful than the rocket’s current version.

30%?  Where did 30% come from?

We were told that the M1D engines were certified to 85% design spec before.  A 17.6% increase in existing thrust would bring it to 100% design spec.

Are they going *further* than that?

SpaceX has a fishing story. It gets bigger each time someone speaks.

In reality, there a lot a variables.

All we do know is they  are working on improving the F9 and they have a 5300kg payload to GTO.

I assume they have acceptable margin for that payload.

They can't get too much larger, otherwise there is no point for the FH, except for potential RTLS missions and BEO. Even if they could throw around 6300kg to GTO with a F9, they could cover practically all satellites. (ViaSat2 is 6750kg)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 03/21/2015 03:24 AM
SpaceX seems to think a RTLS Falcon Heavy would be cheaper than an expendable Falcon 9.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: go4mars on 03/21/2015 03:34 AM
And anticipating some people now speculating that FH will have 8 engines per core in 3....2...1... Sigh, it is inevitable.


I notice that model shows what appeared to be LOX feedlines running down the outside of the stage.  I was wondering why this was the case, as it had been previously established that the LOX feed runs down the center of the kerosene tank, with the tank making a torus shape around it.

But then I realized that by moving the LOX feed to the outside of the rocket, they gain a significant amount of volume on the inside.  This could be a way to accomplish their stated goals of increasing tank capacity without requiring a tank stretch and the cascade of changes that would entail.
I thought it had to do with crossfeed.  But probably not.       ..?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: S.Paulissen on 03/21/2015 04:02 AM
Pre-existing.


Credit: SpaceX.

Found on:
http://space.skyrocket.de/doc_lau_det/falcon-9_v1-1.htm
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 03/21/2015 04:06 AM
do legs look the same as current ones? thought they would look different ..isn't there a new leg being developed?
jb

That model is probably in the wind tunnel now.  The cafeteria gets all the old stuff.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 03/21/2015 04:08 AM
Reposted from the General Falcon discussion thread:

I notice that model shows what appeared to be LOX feedlines running down the outside of the stage.  I was wondering why this was the case, as it had been previously established that the LOX feed runs down the center of the kerosene tank, with the tank making a torus shape around it.

But then I realized that by moving the LOX feed to the outside of the rocket, they gain a significant amount of volume on the inside.  This could be a way to accomplish their stated goals of increasing tank capacity without requiring a tank stretch and the cascade of changes that would entail.

Shouldn't such feedlines start at the bottom of the LOX tank?    But yeah, what else can they be?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/21/2015 06:37 AM
Pre-existing.


Credit: SpaceX.

Found on:
http://space.skyrocket.de/doc_lau_det/falcon-9_v1-1.htm

Yep. Not a LOX line - this is where power and communications is routed from the top to the bottom of each stage. It is not visible in most shots (always faces the T/E at launch), that one picture does highlight it nicely, though.

Again... This is not a new F9 core feature. Relax.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 03/21/2015 06:44 AM
SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
The article *also* says:
Quote
In March 16 and 17 appearances at the Satellite 2015 conference here, Shotwell said the new-version Falcon 9, which has yet to be named, will be about 30 percent more powerful than the rocket’s current version.

30%?  Where did 30% come from?

We were told that the M1D engines were certified to 85% design spec before.  A 17.6% increase in existing thrust would bring it to 100% design spec.

Are they going *further* than that?

Careful, don't jump to conclusions. The 30% may simply be how much payload performance is improved. (To LEO or GTO) Not M1D Performance by itself.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Owlon on 03/21/2015 07:26 AM
SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
The article *also* says:
Quote
In March 16 and 17 appearances at the Satellite 2015 conference here, Shotwell said the new-version Falcon 9, which has yet to be named, will be about 30 percent more powerful than the rocket’s current version.

30%?  Where did 30% come from?

We were told that the M1D engines were certified to 85% design spec before.  A 17.6% increase in existing thrust would bring it to 100% design spec.

Are they going *further* than that?

Careful, don't jump to conclusions. The 30% may simply be how much payload performance is improved. (To LEO or GTO) Not M1D Performance by itself.

That's exactly what it sounds like to me. 15% thrust upgrade + LOX subcooling + upper stage 10% stretch = 30% payload increase.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 03/21/2015 08:59 AM


SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
The article *also* says:
Quote
In March 16 and 17 appearances at the Satellite 2015 conference here, Shotwell said the new-version Falcon 9, which has yet to be named, will be about 30 percent more powerful than the rocket’s current version.

30%?  Where did 30% come from?

We were told that the M1D engines were certified to 85% design spec before.  A 17.6% increase in existing thrust would bring it to 100% design spec.

Are they going *further* than that?

Careful, don't jump to conclusions. The 30% may simply be how much payload performance is improved. (To LEO or GTO) Not M1D Performance by itself.

That's exactly what it sounds like to me. 15% thrust upgrade + LOX subcooling + upper stage 10% stretch = 30% payload increase.

Yup, me three - same thought. I also wondered if there might be a small Isp change, especially in light of the change to mixture ratio.

Don't forget also mild chilling of RP-1:-

AvWeek Paris (AvWeekParis):
Shotwell on Falcon 9 Merlin engine upgrade: We're doing slightly chilled RP, mostly chilled oxidizer. "Hey, if Russia can do it..." #satshow
http://twitter.com/AvWeekParis/status/577534249420468224

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate on 03/21/2015 11:06 PM


SpaceNews article has more quotes from Gwynne this week: http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/ (http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/)

Quote
On the Falcon Heavy rocket’s inaugural flight:  “Later this year. The pad will be ready for it by September or October of this year. We’ll get it launched as quickly as we can."
The article *also* says:
Quote
In March 16 and 17 appearances at the Satellite 2015 conference here, Shotwell said the new-version Falcon 9, which has yet to be named, will be about 30 percent more powerful than the rocket’s current version.

30%?  Where did 30% come from?

We were told that the M1D engines were certified to 85% design spec before.  A 17.6% increase in existing thrust would bring it to 100% design spec.

Are they going *further* than that?

Careful, don't jump to conclusions. The 30% may simply be how much payload performance is improved. (To LEO or GTO) Not M1D Performance by itself.

That's exactly what it sounds like to me. 15% thrust upgrade + LOX subcooling + upper stage 10% stretch = 30% payload increase.

Yup, me three - same thought. I also wondered if there might be a small Isp change, especially in light of the change to mixture ratio.

Don't forget also mild chilling of RP-1:-

AvWeek Paris (AvWeekParis):
Shotwell on Falcon 9 Merlin engine upgrade: We're doing slightly chilled RP, mostly chilled oxidizer. "Hey, if Russia can do it..." #satshow
http://twitter.com/AvWeekParis/status/577534249420468224

Cheers, Martin

Ahh, I think I may have it.  30% seemed unrealistically high for any parameter, but I wasn't accounting for everything.

A 30% payload increase to GTO brings GTO payload from 4850kg to 6305kg... *but*, that's not all the mass that reaches GTO.  Dry mass of the upper stage is said to be on the order of 4900kg.

Dry mass to a given orbit should approach scaling with launchpad propellant mass and some power law of specific impulse, but that includes both the payload and the empty upper stage.

Increase total dry mass to GTO by ~15%, and you increase payload to GTO by ~30%.  A combination of prop densification, more propellant volume from a stretch, lower gravity losses, and importantly, moderately higher Isp, might be able to get you to 15% better dry mass to GTO.

PS: The thrust upgrade does not do much, in itself, to increase payload - it only reduces gravity losses very slightly because most of the time the engines are throttled back.  The main benefit of more thrust is you can lift more propellant off the pad.  More thrust probably implies higher chamber pressure and higher Isp (http://forum.nasaspaceflight.com/index.php?topic=32983.msg1326509#msg1326509) though.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: adrianwyard on 04/03/2015 05:58 PM
After some searching I can't find anything definitive on the payload and/or mission planned for the Falcon Heavy Demo flight. Anyone know what the plan is?

Some say it could launch the US Air Force STP-2 mission - others say that's on a subsequent FH flight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 04/06/2015 10:44 PM
Anyone else notice that SpaceX recently raised the list price for Falcon Heavy from $85M to $90M?  Happened sometime in March.

No other change in specs that I can see.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: docmordrid on 04/07/2015 01:43 AM
That's about 5.88%. The CPI went up about 1.7% last year, but that's an imperfect inflation indicator.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/07/2015 01:48 AM
That's about 5.88%. The CPI went up about 1.7% last year, but that's an imperfect inflation indicator.
CPI is just about as good as anything else (although in the near-term, I'd probably exclude gas and food as they fluctuate a lot... you'll end up just looking at the variation in gas and food).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 04/07/2015 06:12 AM
That's about 5.88%. The CPI went up about 1.7% last year, but that's an imperfect inflation indicator.

Or, the introductory pricing period has expired because they received enough initial orders for Falcon Heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Mader Levap on 04/07/2015 09:44 AM
I expect it will be like with F9. Biggest jump in price will happen after paper rocket changes into actual rocket that launched successfully.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 04/07/2015 12:21 PM
I expect it will be like with F9. Biggest jump in price will happen after paper rocket changes into actual rocket that launched successfully.

Nothing like this happened to F9. The price was only adjusted to inflation after it was fixed for a long time.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 04/07/2015 12:30 PM
In the ULA thread reaching GEO was discussed. So Falcon upper stage will need the ability to restart after app. 12h coast. That's quite long. Is it a very large stretch to go from there to 3 days? 3 days would mean it could do LOI.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 04/07/2015 03:15 PM
In the ULA thread reaching GEO was discussed. So Falcon upper stage will need the ability to restart after app. 12h coast. That's quite long. Is it a very large stretch to go from there to 3 days? 3 days would mean it could do LOI.
I believe it's more like 8hs. It's a quarter of an orbit, and a GEO that would mean 6hrs, a GTO must be less.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: groundbound on 04/07/2015 03:40 PM
In the ULA thread reaching GEO was discussed. So Falcon upper stage will need the ability to restart after app. 12h coast. That's quite long. Is it a very large stretch to go from there to 3 days? 3 days would mean it could do LOI.
I believe it's more like 8hs. It's a quarter of an orbit, and a GEO that would mean 6hrs, a GTO must be less.

I especially like how you used the most advanced orbital mechanics simulation to conclude this.  :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 04/07/2015 05:16 PM
In the ULA thread reaching GEO was discussed. So Falcon upper stage will need the ability to restart after app. 12h coast. That's quite long. Is it a very large stretch to go from there to 3 days? 3 days would mean it could do LOI.
I believe it's more like 8hs. It's a quarter of an orbit, and a GEO that would mean 6hrs, a GTO must be less.

I especially like how you used the most advanced orbital mechanics simulation to conclude this.  :)
I'm lazy, so sue me  :P It does require the knowledge that you increase your apogee at perigee, and then circularize and do the plane change simultaneously at apogee. This is for a stock GTO, if they were doing super-syncronous that would be a different profile and might well take 12hs or even more for bi-elliptic transfer. But that also require an extra restart and more coast time. I don't believe they'll want the added risk if they can spare the performance (which a Falcon Heavy should have plenty).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: obi-wan on 04/07/2015 06:59 PM
In the ULA thread reaching GEO was discussed. So Falcon upper stage will need the ability to restart after app. 12h coast. That's quite long. Is it a very large stretch to go from there to 3 days? 3 days would mean it could do LOI.
I believe it's more like 8hs. It's a quarter of an orbit, and a GEO that would mean 6hrs, a GTO must be less.

I especially like how you used the most advanced orbital mechanics simulation to conclude this.  :)
I'm lazy, so sue me  :P It does require the knowledge that you increase your apogee at perigee, and then circularize and do the plane change simultaneously at apogee. This is for a stock GTO, if they were doing super-syncronous that would be a different profile and might well take 12hs or even more for bi-elliptic transfer. But that also require an extra restart and more coast time. I don't believe they'll want the added risk if they can spare the performance (which a Falcon Heavy should have plenty).

5h17m, assuming a Hohmann transfer from 300 km parking orbit to GEO.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: ChrisWilson68 on 04/09/2015 06:33 AM
If the new engine pushes the Falcon heavy towards 60 tonnes to LEO, won't this make the $1 billion Per launch 70 tonne SLS look DOA. $150 mill for 60 tonnes.$1000 mill for 70 tonnes ummm

Does anyone know the figures for falcon heavy with updated engines to LEO
Since cross feeding is no longer being used on the Falcon Heavy I suspect that the upgrades will be used to get it to its advertised lift capacity. SLS is not a good comparison to make. SLS will be capable of almost 90 tonnes from the start. The lift capacity is under reported. The program wanted room for mass growth should it happen, but it hasn't.

The better metric to use instead of payload to low orbit is payload to L2, TLI, TMI. Those are the likely destinations based on the current mission architecture concepts. The only official figures I could find for the Falcon Heavy were to LEO, GTO, or Mars. So the comparison will have to use Mars instead of the more likely L2 or TLI. The Falcon Heavy is capable of 13.2 tonnes to Mars. SLS will initially be able to do 20.2 to Mars, and 31.7 tonnes with the EUS which could be as soon as the 2nd or 3rd launch. SLS will have almost 2.5 times the lift capacity to BEO destinations. It will be able to send more on a Mars trajectory than any currently flying rocket can to LEO.

Which means that the job of SLS can be done with an Earth Departure Stage lifted by a second Falcon Heavy to rendezvous in orbit with the payload.  Two Falcon Heavy's plus an EDS are bound to be a lot cheaper than SLS.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: notsorandom on 04/09/2015 09:00 PM
If the new engine pushes the Falcon heavy towards 60 tonnes to LEO, won't this make the $1 billion Per launch 70 tonne SLS look DOA. $150 mill for 60 tonnes.$1000 mill for 70 tonnes ummm

Does anyone know the figures for falcon heavy with updated engines to LEO
Since cross feeding is no longer being used on the Falcon Heavy I suspect that the upgrades will be used to get it to its advertised lift capacity. SLS is not a good comparison to make. SLS will be capable of almost 90 tonnes from the start. The lift capacity is under reported. The program wanted room for mass growth should it happen, but it hasn't.

The better metric to use instead of payload to low orbit is payload to L2, TLI, TMI. Those are the likely destinations based on the current mission architecture concepts. The only official figures I could find for the Falcon Heavy were to LEO, GTO, or Mars. So the comparison will have to use Mars instead of the more likely L2 or TLI. The Falcon Heavy is capable of 13.2 tonnes to Mars. SLS will initially be able to do 20.2 to Mars, and 31.7 tonnes with the EUS which could be as soon as the 2nd or 3rd launch. SLS will have almost 2.5 times the lift capacity to BEO destinations. It will be able to send more on a Mars trajectory than any currently flying rocket can to LEO.

Which means that the job of SLS can be done with an Earth Departure Stage lifted by a second Falcon Heavy to rendezvous in orbit with the payload.  Two Falcon Heavy's plus an EDS are bound to be a lot cheaper than SLS.
No it can't the math doesn't work out. Two Falcon Heavies can't throw as much through TMI. Its not just 13.2 + 13.2. You have to subtract the mass of the extra hardware needed to preform the docking, loiter in LEO, and control the stages. Even if one could just add those two numbers it wouldn't equal what an SLS can do once it gets the EUS which will be very soon in the program.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/10/2015 04:37 PM
Will it get it sooner than BFR flies?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: RonM on 04/10/2015 05:04 PM
Will it get it sooner than BFR flies?

A good point, but one based on the occasional SpaceX statement and not an actual plan. While I have confidence in SpaceX, I'd feel better about their BFR once SpaceX announces the design. At this point, at least from our point of view, it's not even a PowerPoint rocket.

Until SpaceX can show progress and test fly their BFR, NASA needs to continue with SLS. Congress may want them to continue SLS even after SpaceX has an operational BFR. It's more of a political decision than technical.

Getting back to FH, if it can become reusable, taking three or four flights to match the capacity of a single SLS might make FH cheaper.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/10/2015 05:32 PM
"Actual plans" by NASA ten years in the future aren't worth anything more.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: libs0n on 04/10/2015 06:15 PM

No it can't the math doesn't work out. Two Falcon Heavies can't throw as much through TMI. Its not just 13.2 + 13.2. You have to subtract the mass of the extra hardware needed to preform the docking, loiter in LEO, and control the stages. Even if one could just add those two numbers it wouldn't equal what an SLS can do once it gets the EUS which will be very soon in the program.

-Use 3 or more launches.

-Use a hydrogen EDS

-Use a SEP EDS

-Not all missions may stretch top specs or perhaps can be configurable to lesser spec’ed layouts.  For instance, if Orion flies with a module, then perhaps that module can be launched separately from the crew in the Falcon Heavy based approach.  Not all Orion flights may carry along such modules and stretch the top specs of the system, as an example.

-You can use Falcon Heavy now and commission a SLS exact matching or exceeding LV later.

-You can investigate upgrades to Falcon Heavy like a hydrogen upper stage.

-Accept a lesser matching Falcon Heavy solution for the benefits a Falcon Heavy based approach brings to the table than top spec obsession.

Falcon Heavy has its own positive qualities like low cost mass delivery to orbit and greater budget space allocation to payload/technology/mission development with less ongoing parasitic LV cost and architectures can be tailored to harness those strengths rather than fit a SLS tailored plan to it, or hypothetical ones.  A comparative basket that each approach could deliver for us I think would see the Falcon Heavy approach be more compelling even if they were not identical.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: notsorandom on 04/10/2015 06:18 PM
Will it get it sooner than BFR flies?
I would wager on it but my attention span doesn't allow me to make bets that far into the future. We know what the Block 1B SLS will look like. We know when they are planning to fly it. The factory to build it exists. The launch pad to launch it exists. We know what the engines to power it will look like. The engines are being qualified right now. The RL-10 is flying now. The RS-25s and SRB casings have already been built for the first EUS flight. SLS want to fly the EUS soon in the program with the second of third launch putting its inaugural flight in the 2021/2022 time frame.

Those things cannot be said about the BFR. Raptor is undergoing very initial testing at Stennis. This type of engine take many years to become operational. A rocket that big is going to take infrastructure like none we have ever seen. I'd say those are the pacing items. The BFR and MCT have a lot of unknowns and ifs right now. Until SpaceX starts talking about them we can only speculate based on scant few details.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: notsorandom on 04/10/2015 07:13 PM

No it can't the math doesn't work out. Two Falcon Heavies can't throw as much through TMI. Its not just 13.2 + 13.2. You have to subtract the mass of the extra hardware needed to preform the docking, loiter in LEO, and control the stages. Even if one could just add those two numbers it wouldn't equal what an SLS can do once it gets the EUS which will be very soon in the program.

-Use 3 or more launches.

-Use a hydrogen EDS

-Use a SEP EDS

-Not all missions may stretch top specs or perhaps can be configurable to lesser spec’ed layouts.  For instance, if Orion flies with a module, then perhaps that module can be launched separately from the crew in the Falcon Heavy based approach.  Not all Orion flights may carry along such modules and stretch the top specs of the system, as an example.

-You can use Falcon Heavy now and commission a SLS exact matching or exceeding LV later.

-You can investigate upgrades to Falcon Heavy like a hydrogen upper stage.

-Accept a lesser matching Falcon Heavy solution for the benefits a Falcon Heavy based approach brings to the table than top spec obsession.

Falcon Heavy has its own positive qualities like low cost mass delivery to orbit and greater budget space allocation to payload/technology/mission development with less ongoing parasitic LV cost and architectures can be tailored to harness those strengths rather than fit a SLS tailored plan to it, or hypothetical ones.  A comparative basket that each approach could deliver for us I think would see the Falcon Heavy approach be more compelling even if they were not identical.
I don't have time to give a detailed response to all these points. Also this is starting to become an SLS vs SpaceX thread so I will limit myself to just the SpaceX aspect of this. Falcon Heavy will not bet getting an LH2 upper stage. That goes against everything Elon has said about that fuel. Besides the gain in payload capacity with an LH2 upper stage would only push the payload LEO capacity into the low 60mt area. The LH2 upper stage would certainly be more expensive and only used by one customer on a very small number of flights. SpaceX's other customers don't have a need for cross-feeding let alone capacity beyond what that would provide. Not worth the extra cost for the improved performance. 

Supplying LH2 to an EDS on top of the rocket would require some pretty extensive launch pad work and down time even if the upper stage were left the same. SpaceX's bottle necks right now are factory production and number of launch pads. Once again this would only be for one customer and for a few missions.

I think SEP is the way we are going to get to Mars. However SpaceX isn't working on it right now. Also spiraling out from LEO will take a very long time. The payload and/or crew will have plenty of time to get a good soak in the Van Allen belts.

The Falcon Heavy will play an important part of any exploration architecture. So will SLS. They are not mutually exclusive and complement each other's capabilities. If it makes sense to fly something on the Falcon than do it and free up an SLS launch for something which can only fly on it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 04/10/2015 09:27 PM
Also this is starting to become an SLS vs SpaceX thread so I will limit myself to just the SpaceX aspect of this.

My concern is that unless we commoditize moving mass off of Earth, we won't be able to afford to go anywhere.

The SLS represents a "closed system", in that hardware built to maximize the capabilities of the SLS would not be able to be launched on anything but the SLS.  That could limit international participation, and it makes the SLS a Single-Point-Of-Failure system.  Plus the SLS will not be close to the lowest $/kg way to space.

Building hardware that can only be launched on the Falcon Heavy would have the same effect, so I wouldn't want to advocate for that approach either.

So to me at least, when thinking about a future exploration architecture, I think the best use of the Falcon Heavy won't be in lifting more than any other launcher, but by lowering the cost of moving commodity mass to space - payloads that other commercial launchers could also move to space, but that Falcon Heavy can do for a far lower price.

The goal would be to average down the cost by still using other existing launchers, but within an exploration system the overall cost would go down because of Falcon Heavy.

And I'm completely ignoring any efforts SpaceX may have to go it alone to Mars, so this is just about NASA-only or international exploration efforts.

My $0.02
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: llanitedave on 04/10/2015 11:27 PM
Even though it's not MCT, the Falcon Heavy will be able to launch bigger payloads to Mars and to elsewhere in the solar system than any rocket to date.  I'm hoping there are institutions beyond SpaceX alone that will be able to take advantage of this capability.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: clongton on 04/11/2015 01:02 PM
Also this is starting to become an SLS vs SpaceX thread so I will limit myself to just the SpaceX aspect of this.

Thank you. Mods please keep an eye on this. Thanks
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 04/11/2015 06:53 PM
Does anyone think they will make a metholox Merlin engine?  If so, what kind of capacity would the Falcon heavy have converting all to metholox?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 04/11/2015 07:04 PM
Even though it's not MCT, the Falcon Heavy will be able to launch bigger payloads to Mars and to elsewhere in the solar system than any rocket to date.  I'm hoping there are institutions beyond SpaceX alone that will be able to take advantage of this capability.

Shotwell said at some point the FH will send lots of payload to Mars.  That's good enough for me.  I will bet that SpaceX will be sending more payloads to Mars than any government agency.

A 3-barrel rocket is really a very good staging system (when compared to a three-stage rocket) since you get both first and second staged working simultaneously at launch.  It has a disadvantage with reusability since it leaves the second stage (the center core) far down range.

Or rather, it HAD a disadvantage, until they decided to commit to the ASDS.  That issue is now gone, and I expect them to use it to its full advantage to squeeze everything they can out of the FH.

A higher-ISP second stage would be great of course, but we're talking about a brand new engine, and that kind of effort seems to be channeled strictly towards MCT right now.  If FH, as is, plus barge, is good enough for their early Mars plans, than that's all they need.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/11/2015 07:23 PM
Well, if they do decide that BFR/MCT is just a step too far right now, they could indeed get a huge boost to Falcon Heavy performance (especially to high energy orbits) by going with a Raptor-powered upper stage. But yeah, not really anything solid anywhere (although some guy says that some guy he kind of knows heard during some meeting that they might be considering a Raptor upper stage for Falcon Heavy... but I wouldn't give that much credence right now).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 04/11/2015 07:39 PM
If Raptor is 500k lb thrust and Merlin vacuum is 200k lb thrust, that is a lot more thrust.  Would the upper be widened to hold more fuel, or stretched?  Unless the Raptor vacuum can be throttled down. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/11/2015 07:41 PM
If Raptor is 500k lb thrust and Merlin vacuum is 200k lb thrust, that is a lot more thrust.  Would the upper be widened to hold more fuel, or stretched?  Unless the Raptor vacuum can be throttled down.
No doubt it'd be widened and/or stretched, but yeah, it can be throttled down (or at least they could certainly design it that way since they'll need to be able to throttle the first stage Raptors anyway).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dror on 04/11/2015 08:05 PM
Does anyone think they will make a metholox Merlin engine?  If so, what kind of capacity would the Falcon heavy have converting all to metholox?

My bold

What I would like to know is the expected isp of a gas generator methalox engine compared to a kerolox gg engine, and that would be a good beginning to answer your question.

If the difference is not substantial , I would stick to the speculation (adopted from the mini BFR thread)  that with\without crossfeed, the next step is a reusable single raptor upper stage for FH, followed by replacing both F9R and FH cores with a 9 raptor reusable booster.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TaurusLittrow on 04/11/2015 08:39 PM
Photo of HIF posted on SpaceX web site April 6
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/11/2015 09:03 PM
Does anyone think they will make a metholox Merlin engine?  If so, what kind of capacity would the Falcon heavy have converting all to metholox?

My bold

What I would like to know is the expected isp of a gas generator methalox engine compared to a kerolox gg engine, and that would be a good beginning to answer your question.

If the difference is not substantial , I would stick to the speculation (adopted from the mini BFR thread)  that with\without crossfeed, the next step is a reusable single raptor upper stage for FH, followed by replacing both F9R and FH cores with a 9 raptor reusable booster.

In a practical way you don't obtain substantial improvement with methane over querosene, the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%). Falcon 9 is designed for road transport, if you switch to methane you have to increase the size of the tanks and you lose this capability, so it doesn't make sense.

Methane improves the reutilization of the engines through a cleaner combustion with les maintenance. The second good point of methane over querosene is the capacity of ISRU production in Mars.

What it would work would be a querosene closed cycle Merlin Engine to improve the ISP, with methane you would end up with a too long stick.

Methane has never been used for rockets because querosene and hydrogen work better. This might change with reutilization once you don't care about road transportation (BFR).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deruch on 04/11/2015 09:25 PM
Does anyone think they will make a metholox Merlin engine?  If so, what kind of capacity would the Falcon heavy have converting all to metholox?

My bold

What I would like to know is the expected isp of a gas generator methalox engine compared to a kerolox gg engine, and that would be a good beginning to answer your question.

If the difference is not substantial , I would stick to the speculation (adopted from the mini BFR thread)  that with\without crossfeed, the next step is a reusable single raptor upper stage for FH, followed by replacing both F9R and FH cores with a 9 raptor reusable booster.
In a practical way you don't obtain substantial improvement with methane over querosene, the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%). Falcon 9 is designed for road transport, if you switch to methane you have to increase the size of the tanks and you lose this capability, so it doesn't make sense.

This might not be quite as big of an issue as is normally argued if they can launch from VAFB.  It might be possible to transport a wider diameter stage from Hawthorne to VAFB by boat/barge.  Though, they might lose the ability to test it in TX first.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: hkultala on 04/11/2015 09:40 PM
This might not be quite as big of an issue as is normally argued if they can launch from VAFB.  It might be possible to transport a wider diameter stage from Hawthorne to VAFB by boat/barge.  Though, they might lose the ability to test it in TX first.

VAFB only works for polar trajectories. No GTO launches from VAFB, and considerable payload hit for VAFB launches to earth escape trajectories.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/11/2015 09:43 PM
In a practical way you don't obtain substantial improvement with methane over querosene, the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%). Falcon 9 is designed for road transport, if you switch to methane you have to increase the size of the tanks and you lose this capability, so it doesn't make sense.

This might not be quite as big of an issue as is normally argued if they can launch from VAFB.  It might be possible to transport a wider diameter stage from Hawthorne to VAFB by boat/barge.  Though, they might lose the ability to test it in TX first.

What is the advantage? Kerosene is already great, very dense and easy to storage. If you don't need to collect from Mars is better than methane.

Falcon 9 is the workhorse of SpaceX and will be for the next years, it's great advantage is it's practicality in all the ways.
 
The improvement would be a closed cycle Merline engine (Keroesene mini Raptor). This would improve the performance and keep it's practicalities. But this new Merlin should be cheap to produce and easy to maintain between launches to improve the current rocket.

I don't see any practical advantage on switchin F9/FH to methane.

FMPOV a good strategy would be to develop raptor with multiple combustion chambers like RD-170 family. Start with 2 chambers 500mlb symilar to RD-180 and later you can go to 1 chamber and have something better in (250mlb vs 200mlb) thrust and ISP than with Merlin. This smaller raptor I would adapt it for Kerosene and if it is cheap enough then use it for Falcon family in the same 9 + 1 configuration. Then you get a F9 with 16T to LEO and FH with 60T to LEO.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/11/2015 10:02 PM
SpaceX isn't going to make a methane Merlin, end of story.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ronsmytheiii on 04/11/2015 10:13 PM
What is the advantage? Kerosene is already great, very dense and easy to storage. If you don't need to collect from Mars is better than methane.


Methane would significantly improve performance for the upper-stage, while not really helping at all for the booster stage. If SpaceX switched to a methane upper-stage, performance to GTO would improve significantly (which is a big money maker). They could lift large GTO payloads on a single core Falcon 9, or two large payloads on a Heavy.

It is too bad SpaceX isn't going to use their Raptor work for a Methane based upper-stage engine, would help them to pay for further development.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dror on 04/11/2015 10:16 PM
Does anyone think they will make a metholox Merlin engine?  If so, what kind of capacity would the Falcon heavy have converting all to metholox?

My bold

What I would like to know is the expected isp of a gas generator methalox engine compared to a kerolox gg engine, and that would be a good beginning to answer your question.

If the difference is not substantial , I would stick to the speculation (adopted from the mini BFR thread)  that with\without crossfeed, the next step is a reusable single raptor upper stage for FH, followed by replacing both F9R and FH cores with a 9 raptor reusable booster.

In a practical way you don't obtain substantial improvement with methane over querosene, the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%). Falcon 9 is designed for road transport, if you switch to methane you have to increase the size of the tanks and you lose this capability, so it doesn't make sense.

Methane improves the reutilization of the engines through a cleaner combustion with les maintenance. The second good point of methane over querosene is the capacity of ISRU production in Mars.

What it would work would be a querosene closed cycle Merlin Engine to improve the ISP, with methane you would end up with a too long stick.

Methane has never been used for rockets because querosene and hydrogen work better. This might change with reutilization once you don't care about road transportation (BFR).

Well, the question was about a methalox Merlin (gas generator) , not about a kerolox mini Raptor (staged combustion) .
I reckon that was assuming the first option is easier to develop.

Thanks for your answer -
"the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%)."

As I get it, since the rocket equation is exponential for isp, the 3,6% isp increase can't compare with the 22% volume reduction. Some math has to be made in order to know if the payload increases or decreases with these changes and the same total volume of the F9.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/11/2015 10:38 PM
Well, the question was about a methalox Merlin (gas generator) , not about a kerolox mini Raptor (staged combustion) .
I reckon that was assuming the first option is easier to develop.

Thanks for your answer -
"the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%)."

As I get it, since the rocket equation is exponential for isp, the 3,6% isp increase can't compare with the 22% volume reduction. Some math has to be made in order to know if the payload increases or decreases with these changes and the same total volume of the F9.

If you keep the same tanks you have 22% less fuel, no way it compensates throught ISP. Otherwise Musk would have gone for methane from the beginning.

In case you make bigger tanks (22%) then you increase the tank weight in small percentage and is here where you loose the small advantage in ISP.

Same engine for Kerosene, Methane, Hydrogen give ISP of: 355,368,456s. For Hydrogen you always need bigger tanks with isolation, so for same weight of fuel you have much more weight, but the ISP (+24%) here is making big big difference. In kerosene VS methane the difference is really small and you probably end up in something symilar. But in the particular case of Falcon rockets there is no discussion as the tank size is the big constraint that can not grow. But even if it could grow I don't see any advantage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dglow on 04/11/2015 11:39 PM
Falcon 9 is designed for road transport, if you switch to methane you have to increase the size of the tanks and you lose this capability, so it doesn't make sense.

But in the particular case of Falcon rockets there is no discussion as the tank size is the big constraint that can not grow.

The F9 second stage could grow in length and remain road-transportable. The diameter is the constraint.

Your argument that the corresponding increase in dry mass might outweigh the benefits of switching to methalox stands. But don't argue that stage size/transport would prohibit such a move.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: groundbound on 04/11/2015 11:41 PM
But in the particular case of Falcon rockets there is no discussion as the tank size is the big constraint that can not grow. But even if it could grow I don't see any advantage.

Tank diameter is not an absolute constraint. It is a constraint that SpaceX has placed upon itself to reduce costs, if it ever truly gets in the way of an important goal it will be discarded. A true need to get FH a much higher energy upper stage might be enough reason if that market opportunity ever materializes.

But that would be years down the road, and SpaceX will likely never encounter the business need.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 04/12/2015 12:36 AM
Well, the question was about a methalox Merlin (gas generator) , not about a kerolox mini Raptor (staged combustion) .
I reckon that was assuming the first option is easier to develop.

Thanks for your answer -
"the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%)."

As I get it, since the rocket equation is exponential for isp, the 3,6% isp increase can't compare with the 22% volume reduction. Some math has to be made in order to know if the payload increases or decreases with these changes and the same total volume of the F9.

If you keep the same tanks you have 22% less fuel, no way it compensates throught ISP. Otherwise Musk would have gone for methane from the beginning.

In case you make bigger tanks (22%) then you increase the tank weight in small percentage and is here where you loose the small advantage in ISP.

Same engine for Kerosene, Methane, Hydrogen give ISP of: 355,368,456s. For Hydrogen you always need bigger tanks with isolation, so for same weight of fuel you have much more weight, but the ISP (+24%) here is making big big difference. In kerosene VS methane the difference is really small and you probably end up in something symilar. But in the particular case of Falcon rockets there is no discussion as the tank size is the big constraint that can not grow. But even if it could grow I don't see any advantage.
But this is no case for SpaceX. They are going from RP-1 Gas Generator to Methane Full Flow. Big difference. And actual RSC Energyia engineer has calculated that a methane Falcon 9 with the same dimensions as v1.1, but engine performance as Raptor, would get 25tonnes to LEO and 8tonnes to GTO. That covers 100% of current market. And that's without the 10% tank lengething and propellant densification that SpaceX is implementing on the enhanced Falcon 9, nor 2050 aluminum tanks and other "cheap" enhancements. Probably could hit 30/10 with that.
If they do a mini Raptor upper stage, they'll probably move the cores later. They'll have the performance margin for upper stage reuse and validate everything for MCT for a lot less money than a whole new development.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: HIP2BSQRE on 04/12/2015 12:48 AM
Well, the question was about a methalox Merlin (gas generator) , not about a kerolox mini Raptor (staged combustion) .
I reckon that was assuming the first option is easier to develop.

Thanks for your answer -
"the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%)."

As I get it, since the rocket equation is exponential for isp, the 3,6% isp increase can't compare with the 22% volume reduction. Some math has to be made in order to know if the payload increases or decreases with these changes and the same total volume of the F9.


If you keep the same tanks you have 22% less fuel, no way it compensates throught ISP. Otherwise Musk would have gone for methane from the beginning.

In case you make bigger tanks (22%) then you increase the tank weight in small percentage and is here where you loose the small advantage in ISP.

Same engine for Kerosene, Methane, Hydrogen give ISP of: 355,368,456s. For Hydrogen you always need bigger tanks with isolation, so for same weight of fuel you have much more weight, but the ISP (+24%) here is making big big difference. In kerosene VS methane the difference is really small and you probably end up in something symilar. But in the particular case of Falcon rockets there is no discussion as the tank size is the big constraint that can not grow. But even if it could grow I don't see any advantage.
But this is no case for SpaceX. They are going from RP-1 Gas Generator to Methane Full Flow. Big difference. And actual RSC Energyia engineer has calculated that a methane Falcon 9 with the same dimensions as v1.1, but engine performance as Raptor, would get 25tonnes to LEO and 8tonnes to GTO. That covers 100% of current market. And that's without the 10% tank lengething and propellant densification that SpaceX is implementing on the enhanced Falcon 9, nor 2050 aluminum tanks and other "cheap" enhancements. Probably could hit 30/10 with that.
If they do a mini Raptor upper stage, they'll probably move the cores later. They'll have the performance margin for upper stage reuse and validate everything for MCT for a lot less money than a whole new development.

baldusi,

Is that what you think Spacex will do?  How long do you think that this development would take?  Do you think Spacex will do a min-raptor upper stage or just use the BO engine to replace the current upper stage?  How much would estimate this would cost?  How would this affect Spacex prices?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/12/2015 02:28 AM
But this is no case for SpaceX. They are going from RP-1 Gas Generator to Methane Full Flow. Big difference. And actual RSC Energyia engineer has calculated that a methane Falcon 9 with the same dimensions as v1.1, but engine performance as Raptor, would get 25tonnes to LEO and 8tonnes to GTO. That covers 100% of current market. And that's without the 10% tank lengething and propellant densification that SpaceX is implementing on the enhanced Falcon 9, nor 2050 aluminum tanks and other "cheap" enhancements. Probably could hit 30/10 with that.
If they do a mini Raptor upper stage, they'll probably move the cores later. They'll have the performance margin for upper stage reuse and validate everything for MCT for a lot less money than a whole new development.

Humm I cannot argue because I have no data but 25 tones losing 22% fuel mass is hard to believe. I would expect something similar to what you have now (13-14t to LEO). Zenit rocket with slightly less mass than F9 V1.1 and best full flow kerosene engine works 13500kg to LEO. Maybe could be slightly better, but 25 tones... anyway, time will tell.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 04/12/2015 08:02 AM
If Raptor is 500k lb thrust and Merlin vacuum is 200k lb thrust, that is a lot more thrust.  Would the upper be widened to hold more fuel, or stretched?  Unless the Raptor vacuum can be throttled down.

If you assume 550 klbf for the vac version (~250 tf), that would need a minimum ~20t payload for 6g burnout @ 50% throttle.

Fine for LEO with FHR, but not for GTO / escape unless they go with FHE (maybe recover the boosters?)

Good for a prop tanker for MCT, though.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GORDAP on 04/12/2015 11:50 AM
Well, the question was about a methalox Merlin (gas generator) , not about a kerolox mini Raptor (staged combustion) .
I reckon that was assuming the first option is easier to develop.

Thanks for your answer -
"the slight improvement on ISP (3,8%) is more than lost in the higher volume (22%)."

As I get it, since the rocket equation is exponential for isp, the 3,6% isp increase can't compare with the 22% volume reduction. Some math has to be made in order to know if the payload increases or decreases with these changes and the same total volume of the F9.

If you keep the same tanks you have 22% less fuel, no way it compensates throught ISP. Otherwise Musk would have gone for methane from the beginning.

In case you make bigger tanks (22%) then you increase the tank weight in small percentage and is here where you loose the small advantage in ISP.

Same engine for Kerosene, Methane, Hydrogen give ISP of: 355,368,456s. For Hydrogen you always need bigger tanks with isolation, so for same weight of fuel you have much more weight, but the ISP (+24%) here is making big big difference. In kerosene VS methane the difference is really small and you probably end up in something symilar. But in the particular case of Falcon rockets there is no discussion as the tank size is the big constraint that can not grow. But even if it could grow I don't see any advantage.

I think some of your figures might be a little off.  The estimate I've seen several times for the ISP of a vacuum Raptor is 380, and the best estimate I've seen for the ISP of the present upper stage Falcon is 345.  So this would be more like a 10% ISP improvement rather than 3.8%.  And with the exponential nature of the rocket equation, this is quite significant.

If SpaceX goes this route, I don't think they'd stick to the present volume and diameter for the 2nd stage.  They'd probably go with a larger diameter (hmm, maybe about the diameter of the hammerhead shroud?) and probably a little heavier overall.  Yes, they'd lose road transport, but I think that's much less important if the stage becomes reusable, which would be the whole point of this exercise.  In the Reddit AMA Musk said they couldn't (or wouldn't) pursue reusability for the second stage due to the difficulty of doing it with a relatively low ISP stage.  I've got to think that admission sticks in his craw just a little bit, given how he's repeatedly stressed 'rapid and essentially complete reusability' for a good while now.

With a heavier US and payload they'd have to stiffen the center core a little more, but they're already doing this, so it would just be a bit more of the same.  Also, staging would occur earlier in the flight, but this helps the cause of reusability, since it may be the difference between RTLS for the center core versus barge landing for many flights.

I think a beefier, more energetic upper stage really makes sense for the Falcon Heavy, but probably not for the Falcon 9.  If they go down this route, I'd think it signals that they view the FH as their workhorse for the next 5-8 years (versus the F9), which may make sense given their plans for a constellation, and maybe some other big ventures we're not aware of yet.  And if they do the new Raptor based US, I'd bet the next evolutionary step would be to replace the 3 stick heavy with a single stick Raptor based 1st stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: clongton on 04/12/2015 12:23 PM
Do you think Spacex will do a min-raptor upper stage or just use the BO engine to replace the current upper stage?

SpaceX is not going to use a non-SpaceX engine in any of its launch vehicles - period. Whatever they use will be built in-house.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kabloona on 04/12/2015 02:07 PM
Do you think Spacex will do a min-raptor upper stage or just use the BO engine to replace the current upper stage?

SpaceX is not going to use a non-SpaceX engine in any of its launch vehicles - period. Whatever they use will be built in-house.

Unicorns would have to dance in flame ducts before Musk would use an engine from Jeff Bezos.  ;)

http://spacenews.com/37389musk-calls-out-blue-origin-ula-for-phony-blocking-tactic-on-shuttle-pad/
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/12/2015 02:14 PM
If Raptor is 500k lb thrust and Merlin vacuum is 200k lb thrust, that is a lot more thrust.  Would the upper be widened to hold more fuel, or stretched?  Unless the Raptor vacuum can be throttled down.

If you assume 550 klbf for the vac version (~250 tf), that would need a minimum ~20t payload for 6g burnout @ 50% throttle.

Fine for LEO with FHR, but not for GTO / escape unless they go with FHE (maybe recover the boosters?)

Good for a prop tanker for MCT, though.

Cheers, Martin
Should be able to throttle lower than that.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GORDAP on 04/12/2015 03:41 PM
If Raptor is 500k lb thrust and Merlin vacuum is 200k lb thrust, that is a lot more thrust.  Would the upper be widened to hold more fuel, or stretched?  Unless the Raptor vacuum can be throttled down.

If you assume 550 klbf for the vac version (~250 tf), that would need a minimum ~20t payload for 6g burnout @ 50% throttle.

Fine for LEO with FHR, but not for GTO / escape unless they go with FHE (maybe recover the boosters?)

Good for a prop tanker for MCT, though.

Cheers, Martin

Wouldn't this be 6g only if the upper stage itself was massless?  I think the present one is about 4 mt empty.  Switching from Merlin to Raptor probably will add 1 mt.  If it's to be reusable, then you also would be looking at adding TPS, legs, grid fins + hydrolics, etc., not to mention the landing fuel.  I can easily see this approaching 10 mt total.  So at 50% throttle and a 20 mt payload, you'd only be looking at about 4 g at burnout.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 04/12/2015 04:41 PM
If there was to be a higher(er) energy FH upper stage with an in-house engine, I'd expect it to be something like this> 5.2m barrel size (the same diameter as the PLF) and the same length as the kerosene-fuelled U/S. Whilst a 'Merlin-M' has not evidently in development, I'd certainly consider having it in a 'paper only' development phase to minimise delays if extra beyond-LEO performance is needed and Raptor is further off than a Methane conversion of the Merlin-VAC.

There is a lot of 'ifs' in that and I doubt it would happen unless Musk were certain of a customer or two who needed the performance. That said, a 360-380s U/S would be an interesting addition to the vehicle.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/12/2015 04:48 PM
I think some of your figures might be a little off.  The estimate I've seen several times for the ISP of a vacuum Raptor is 380, and the best estimate I've seen for the ISP of the present upper stage Falcon is 345.  So this would be more like a 10% ISP improvement rather than 3.8%.  And with the exponential nature of the rocket equation, this is quite significant.

This ISP are between different fuels for same X engine. The big increase in ISP between merlin and raptor is mainly because of the full flow engine not because of the fuel. I think it would make a lot of sense to have a full flow engine for the upper stage and improve the ISP.
What I don't see is the switch to methane. A mini raptor methane upper stage would fit and maybe in 5 years we will see it in case they have a mini-raptor, but FMPOV a kerosene mini raptor would fit better. The switch between kerosene and methane "is not a big deal", so I don't see that crazy that once they have a mini raptor they adapt it to kerosene. But thats lot of speculation.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 04/12/2015 04:59 PM
I think some of your figures might be a little off.  The estimate I've seen several times for the ISP of a vacuum Raptor is 380, and the best estimate I've seen for the ISP of the present upper stage Falcon is 345.  So this would be more like a 10% ISP improvement rather than 3.8%.  And with the exponential nature of the rocket equation, this is quite significant.

This ISP are between different fuels for same X engine. The big increase in ISP between merlin and raptor is mainly because of the full flow engine not because of the fuel. I think it would make a lot of sense to have a full flow engine for the upper stage and improve the ISP.
What I don't see is the switch to methane. A mini raptor methane upper stage would fit and maybe in 5 years we will see it in case they have a mini-raptor, but FMPOV a kerosene mini raptor would fit better. The switch between kerosene and methane "is not a big deal", so I don't see that crazy that once they have a mini raptor they adapt it to kerosene. But thats lot of speculation.
You're missing the fact that part of the reason Raptor's engine cycle is feasible is because it's using methane instead of kerosene. So methane enables higher Isp by enabling a better engine cycle.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: groundbound on 04/12/2015 05:17 PM
I think some of your figures might be a little off.  The estimate I've seen several times for the ISP of a vacuum Raptor is 380, and the best estimate I've seen for the ISP of the present upper stage Falcon is 345.  So this would be more like a 10% ISP improvement rather than 3.8%.  And with the exponential nature of the rocket equation, this is quite significant.

This ISP are between different fuels for same X engine. The big increase in ISP between merlin and raptor is mainly because of the full flow engine not because of the fuel. I think it would make a lot of sense to have a full flow engine for the upper stage and improve the ISP.
What I don't see is the switch to methane. A mini raptor methane upper stage would fit and maybe in 5 years we will see it in case they have a mini-raptor, but FMPOV a kerosene mini raptor would fit better. The switch between kerosene and methane "is not a big deal", so I don't see that crazy that once they have a mini raptor they adapt it to kerosene. But thats lot of speculation.
You're missing the fact that part of the reason Raptor's engine cycle is feasible is because it's using methane instead of kerosene. So methane enables higher Isp by enabling a better engine cycle.

Yup, my head hurts when even trying to think about full flow with gaseous kerosene.  ;D
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 04/12/2015 05:18 PM
If there was to be a higher(er) energy FH upper stage with an in-house engine, I'd expect it to be something like this> 5.2m barrel size (the same diameter as the PLF) and the same length as the kerosene-fuelled U/S. Whilst a 'Merlin-M' has not evidently in development, I'd certainly consider having it in a 'paper only' development phase to minimise delays if extra beyond-LEO performance is needed and Raptor is further off than a Methane conversion of the Merlin-VAC.

There is a lot of 'ifs' in that and I doubt it would happen unless Musk were certain of a customer or two who needed the performance. That said, a 360-380s U/S would be an interesting addition to the vehicle.

The one thing I can see is that besides needing customers for the capabilities of such an upper stage (which I envisage at around the 200,000 to 225,000 kg of methalox propellant load), is that it really needs to be reusable to be worth the effort. My BOE treatment says you would get at most 8,000 - 10,000 kg for TPS/re-entry recovery stuff before the LEO capability dropped below 50,000kg. The other side of that coin is that the upper stage expendable capability tops out at 60,000 to LEO. Expendable new US makes no sense since it will cost more than twice the current US.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 04/12/2015 06:21 PM
But this is no case for SpaceX. They are going from RP-1 Gas Generator to Methane Full Flow. Big difference. And actual RSC Energyia engineer has calculated that a methane Falcon 9 with the same dimensions as v1.1, but engine performance as Raptor, would get 25tonnes to LEO and 8tonnes to GTO. That covers 100% of current market. And that's without the 10% tank lengething and propellant densification that SpaceX is implementing on the enhanced Falcon 9, nor 2050 aluminum tanks and other "cheap" enhancements. Probably could hit 30/10 with that.
If they do a mini Raptor upper stage, they'll probably move the cores later. They'll have the performance margin for upper stage reuse and validate everything for MCT for a lot less money than a whole new development.

Humm I cannot argue because I have no data but 25 tones losing 22% fuel mass is hard to believe. I would expect something similar to what you have now (13-14t to LEO). Zenit rocket with slightly less mass than F9 V1.1 and best full flow kerosene engine works 13500kg to LEO. Maybe could be slightly better, but 25 tones... anyway, time will tell.
For starters, F9 v1.1 actually does about 16.5/17tonnes to LEO. Second, the Zenit-2 has a smaller upper stage in relationship. And third, the F9 v1.1 is around 95% of pmf in both first and second, while the Zenit-2 is 92% and 90%, respectively. Zenit-2 was a compromise with the Energyia boosters and has too much T/W and is just too heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/12/2015 06:23 PM
You're missing the fact that part of the reason Raptor's engine cycle is feasible is because it's using methane instead of kerosene. So methane enables higher Isp by enabling a better engine cycle.

You mean that the production of a methane stage combustion engine is easier because methane produce less corrossion in plumbing and combustion chamber than the dirty kerosene?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Owlon on 04/12/2015 06:36 PM
You're missing the fact that part of the reason Raptor's engine cycle is feasible is because it's using methane instead of kerosene. So methane enables higher Isp by enabling a better engine cycle.

You mean that the production of a methane stage combustion engine is easier because methane produce less corrossion in plumbing and combustion chamber than the dirty kerosene?

More or less. The Raptor engine will be full flow staged combustion, so it will have both an oxygen-rich and methane-rich preburner. Kerosene-rich preburners just aren't done because they cause horrible coking problems in the turbine. There may be more to it to that, but that's my basic understanding of the issue.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/12/2015 06:38 PM
For starters, F9 v1.1 actually does about 16.5/17tonnes to LEO. Second, the Zenit-2 has a smaller upper stage in relationship. And third, the F9 v1.1 is around 95% of pmf in both first and second, while the Zenit-2 is 92% and 90%, respectively. Zenit-2 was a compromise with the Energyia boosters and has too much T/W and is just too heavy.
Yep, let me re-read the SpaceX methalox forum I forgot that the data from Dimitry gave that high numbers.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jimmy Murdok on 04/12/2015 06:43 PM
More or less. The Raptor engine will be full flow staged combustion, so it will have both an oxygen-rich and methane-rich preburner. Kerosene-rich preburners just aren't done because they cause horrible coking problems in the turbine. There may be more to it to that, but that's my basic understanding of the issue.

That makes sense. So RD-engine family derivatives to methane are "easy", but Raptor to kerosene would be way too complicated. That's big advantage on methane. Thanks.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: tp1024 on 04/12/2015 07:03 PM
You're missing the fact that part of the reason Raptor's engine cycle is feasible is because it's using methane instead of kerosene. So methane enables higher Isp by enabling a better engine cycle.

You mean that the production of a methane stage combustion engine is easier because methane produce less corrossion in plumbing and combustion chamber than the dirty kerosene?

More or less. The Raptor engine will be full flow staged combustion, so it will have both an oxygen-rich and methane-rich preburner. Kerosene-rich preburners just aren't done because they cause horrible coking problems in the turbine. There may be more to it to that, but that's my basic understanding of the issue.

Well I can imagine that. But in this case I don't understand how the normal gas generator cycle can work.

The gas generator is also kerosene rich and the gas gets pushed through the turbine just fine, before being dumped as one big black sooty stream of evil. So maybe the coking problem is with the injectors into the burning chamber instead? Those are fairly small orifices and should be much more vulnerable to coking.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 04/12/2015 07:25 PM
If Raptor is 500k lb thrust and Merlin vacuum is 200k lb thrust, that is a lot more thrust.  Would the upper be widened to hold more fuel, or stretched?  Unless the Raptor vacuum can be throttled down.

If you assume 550 klbf for the vac version (~250 tf), that would need a minimum ~20t payload for 6g burnout @ 50% throttle.

Fine for LEO with FHR, but not for GTO / escape unless they go with FHE (maybe recover the boosters?)

Good for a prop tanker for MCT, though.

Cheers, Martin

Wouldn't this be 6g only if the upper stage itself was massless?  I think the present one is about 4 mt empty.  Switching from Merlin to Raptor probably will add 1 mt.  If it's to be reusable, then you also would be looking at adding TPS, legs, grid fins + hydrolics, etc., not to mention the landing fuel.  I can easily see this approaching 10 mt total.  So at 50% throttle and a 20 mt payload, you'd only be looking at about 4 g at burnout.

 :-[

Urk, yes. You're right.

If the stage (+ etc) is 5T, then a payload would need to be 15t. Assuming min throttle of 50%, as disupted by robotbeat.

With the current 4t stage and 6T+ GTO payload in RTLS form, that would still need a doubling of the dry mass delivered to GTO (10t+ to ~20t), regardless of how much is stage, and how much payload.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Space Ghost 1962 on 04/12/2015 07:37 PM
You're missing the fact that part of the reason Raptor's engine cycle is feasible is because it's using methane instead of kerosene. So methane enables higher Isp by enabling a better engine cycle.

You mean that the production of a methane stage combustion engine is easier because methane produce less corrossion in plumbing and combustion chamber than the dirty kerosene?

More or less. The Raptor engine will be full flow staged combustion, so it will have both an oxygen-rich and methane-rich preburner. Kerosene-rich preburners just aren't done because they cause horrible coking problems in the turbine. There may be more to it to that, but that's my basic understanding of the issue.

Well I can imagine that. But in this case I don't understand how the normal gas generator cycle can work.

The gas generator is also kerosene rich and the gas gets pushed through the turbine just fine, before being dumped as one big black sooty stream of evil. So maybe the coking problem is with the injectors into the burning chamber instead? Those are fairly small orifices and should be much more vulnerable to coking.

Stop going OT for this thread - take it to Q/A or Merlin or Raptor thread. Simple answer: GG combustion temps too low - "underburn", CC combustion temps "overburn" thus coking/etc, FFSC attempts ideal combustion of an almost ideal hydrocarbon. No Merlin/F9 methane. End of dumb OT.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: notsorandom on 04/13/2015 06:50 PM
If there was to be a higher(er) energy FH upper stage with an in-house engine, I'd expect it to be something like this> 5.2m barrel size (the same diameter as the PLF) and the same length as the kerosene-fuelled U/S. Whilst a 'Merlin-M' has not evidently in development, I'd certainly consider having it in a 'paper only' development phase to minimise delays if extra beyond-LEO performance is needed and Raptor is further off than a Methane conversion of the Merlin-VAC.

There is a lot of 'ifs' in that and I doubt it would happen unless Musk were certain of a customer or two who needed the performance. That said, a 360-380s U/S would be an interesting addition to the vehicle.
A few days ago in another thread I worked out some very crude numbers for a Methane powered Falcon Heavy upper stage. Well not really, I used a fuel with methane's ISP and RP-1's density for a best case, unrealistic, yet super easy to calculate figure. Even if one could just up the ISP to 370s the payload goes up only by 3-4 mt. Falcon Heavy would not see even that much improvement to its LEO payload since the tanks would get bigger and heavier. One might be able to make the upper stage deliver a bigger portion of the total Delta V of the rocket by changing the stage sizes and do other tricks. However methane is not likely to to increase the payload to the point where replacing the upper stage and its engine is worth the headache.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 04/13/2015 07:17 PM
A cryogenic upper stage's purpose wouldn't be anything to do with LEO performance - that's already high enough with kerosene. It's point would be to increase BLEO performance. More of the 55-ish tonnes to LEO being sent through TOI.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Rebel44 on 04/15/2015 09:40 PM
SpaceX Sends Air Force an Outline for Falcon Heavy Certification - See more at: http://spacenews.com/spacex-sends-air-force-an-outline-for-falcon-heavy-certification/#sthash.0Wzwy5m7.dpuf

Quote
COLORADO SPRINGS, Colo. — SpaceX says it sent the U.S. Air Force an updated letter of intent April 14 outlining a certification process for its Falcon Heavy rocket to launch national security satellites.

SpaceX hopes to have its Falcon Heavy rocket certified by 2017, Gwynne Shotwell, the company’s president and chief operating officer, told SpaceNews in an April 14 interview.
- See more at: http://spacenews.com/spacex-sends-air-force-an-outline-for-falcon-heavy-certification/#sthash.0Wzwy5m7.dpuf
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: rcoppola on 04/15/2015 10:56 PM
SpaceX Sends Air Force an Outline for Falcon Heavy Certification - See more at: http://spacenews.com/spacex-sends-air-force-an-outline-for-falcon-heavy-certification/#sthash.0Wzwy5m7.dpuf

Quote
COLORADO SPRINGS, Colo. — SpaceX says it sent the U.S. Air Force an updated letter of intent April 14 outlining a certification process for its Falcon Heavy rocket to launch national security satellites.

SpaceX hopes to have its Falcon Heavy rocket certified by 2017, Gwynne Shotwell, the company’s president and chief operating officer, told SpaceNews in an April 14 interview.
- See more at: http://spacenews.com/spacex-sends-air-force-an-outline-for-falcon-heavy-certification/#sthash.0Wzwy5m7.dpuf
Interesting. It is after all exactly what the last Assured Access Congressional Hearing was requesting. I believe it was something to the effect of, "Please have that FH ready as soon as possible." A 2017 certification, IMO, puts real pressure on ULA in that it makes needing to extend the RD-180 past 2019 a mute point. (Except for the VI issue) This is going to get very interesting. Not that it isn't already.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 04/16/2015 06:28 AM
Interesting. It is after all exactly what the last Assured Access Congressional Hearing was requesting. I believe it was something to the effect of, "Please have that FH ready as soon as possible." A 2017 certification, IMO, puts real pressure on ULA in that it makes needing to extend the RD-180 past 2019 a mute point. (Except for the VI issue) This is going to get very interesting. Not that it isn't already.

Right, it is the signal to Congress and the Airforce. We will be ready by 2017, will you delay us? At the congressional hearing I recall Gwynne Shotwell talking about 2018 and when the Airforce General was asked if that is realistic he said something like "It is optimistic but I won't bet against SpaceX".

Vertical Integration is not an issue IMO. When the demand is there they will have it ready by end of 2016. They have the plans ready to execute at LC-39A and no doubt can do the same in Vandenberg.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dglow on 04/16/2015 07:26 AM
Surprising...

Quote from: Gwynne Shotwell
Shotwell said she expects the Falcon Heavy rocket to fly once this year, three times in 2016 and three to five times in 2017.
“The market is huge,” she said. “The market is bigger in the commercial marketplace than it is for the single stick Falcon 9.”
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 04/16/2015 10:50 AM
Surprising...

Quote from: Gwynne Shotwell
Shotwell said she expects the Falcon Heavy rocket to fly once this year, three times in 2016 and three to five times in 2017.
“The market is huge,” she said. “The market is bigger in the commercial marketplace than it is for the single stick Falcon 9.”

Very. I'm not saying that she's misstating but I do wonder who the potential customers in the 50t IMLEO/17t GTO market might be.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 04/16/2015 11:59 AM
I looked on the launchs coming up.  Can't find it now to link it.  However, one Falcon Heavy in 2016 0r 2017 was going to launch 17 satelites at one time. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: e of pi on 04/16/2015 12:11 PM
Surprising...Very. I'm not saying that she's misstating but I do wonder who the potential customers in the 50t IMLEO/17t GTO market might be.
I think the better way of thinking about it is the number of customers in the >6t to GTO market at a price of roughly $100m. That's about half Ariane, and competitive with Proton without the issues of working with Russians. Even without employing the ful capacity, Falcon Heavy can be the cheaper $/kg option. The customer doesn't have to be using the full capacity to choose FH, they just have to be looking for (1) more than F9R can lift and (2) not seeing a competing launcher in the class that can match that price.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 04/16/2015 12:18 PM
competitive with Proton without the issues of working with Russians.

Working with the USA is a PITA as well. As it is ESA finds it easier to keep buying Soyus even at inflated prices and flying them from Kourou than sending satellites to the USA for launch.

But yes Falcon Heavy with reusable boosters and central core will be very competetive if cost will be as anticipated by SpaceX.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 04/16/2015 01:53 PM
Do you guys think they will develop a methane Merlin?  If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: jzjzjzj on 04/16/2015 01:59 PM
Do you guys think they will develop a methane Merlin?

n1
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 04/16/2015 04:11 PM
I thought they were working on a methane Merlin at one time. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 04/16/2015 04:46 PM
I thought they were working on a methane Merlin at one time.

There was speculation about a methane Merlin on this forum. Otherwise I don't think so.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: FutureSpaceTourist on 04/17/2015 08:34 AM
A blog post about a recent SpaceX visit (http://www.slate.com/blogs/bad_astronomy/2015/04/16/elon_musk_and_mars_spacex_ceo_and_our_multi_planet_species.html?wpsrc=sh_all_dt_tw_top (http://www.slate.com/blogs/bad_astronomy/2015/04/16/elon_musk_and_mars_spacex_ceo_and_our_multi_planet_species.html?wpsrc=sh_all_dt_tw_top)) mentions some Falcon Heavy construction:

Quote
From the café on the mezzanine I can see twin enormous nose cones sitting in the next room, waiting to be used on the demo flight of the Falcon Heavy [...]

Quote
During the tour I also saw dozens of people working on the various components of the Falcons 9 and Heavy.

So hopefully SpaceX are still on track for a launch this year.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Rebel44 on 04/20/2015 05:17 AM
Any info about planned performance of FH to Sun Earth L2 point?

thx

(I tried to search for it, but didnt find it)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 04/20/2015 05:56 AM
Any info about planned performance of FH to Sun Earth L2 point?

thx

(I tried to search for it, but didnt find it)

The big unknowns.

Some calculations had been done by some great contributors of this forum. But that was still with the assumption of crossfeed and stretched side cores. They mostly confirmed the values given for LEO and TMI given on the spaceX website.

Now there will be no stretched side cores and there will very likely be no crossfeed, certainly not soon. However there will be increased Merlin thrust, subcooling and stretching of the second stage. As payload numbers have not changed on their website we may be optimistic enough to assume the new improvements are equivalent to the cancelled old ones.

I personally would love to know wether a Falcon Heavy with side core RTLS and expended central core will be able to deliver a Red Dragon to TMI. My uneducated guess is: probably yes.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: sdsds on 04/20/2015 06:16 AM
Any info about planned performance of FH to Sun Earth L2 point?

SpaceX apparently publishes performance to GTO and to "Mars." The value you want lies somewhere between (essentially it is Earth-escape performance). You could calculate characteristic energies for the two published trajectories, and then interpolate....
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AncientU on 04/29/2015 03:41 PM
Another payload slated for FH:

Quote
Arabsat said it will sign a contract with SpaceX to launch the Arabsat 6A satellite. Arabsat 6A is sized to launch on SpaceX’s Falcon Heavy rocket, according to industry officials.

The company did not identify a launch site for Arabsat 6A, which Lockheed Martin officials said would be ready to fly in 2018, when SpaceX plans to have launch pads ready at Kennedy Space Center in Florida and near Brownsville, Texas, to support Falcon Heavy launches.

The Falcon Heavy’s inaugural test flight is scheduled later this year.
http://spaceflightnow.com/2015/04/29/arabsat-contracts-go-to-lockheed-martin-arianespace-and-spacex/
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: watermod on 04/29/2015 04:04 PM
With the Progress tumble and the explosion at the Virginia pad I can't help thinking that some large dispenser bus launched on a Falcon Heavy would be useful.   Have it park (grappled) to one of the trusses.   The objects dispensed would each have a "docking" device on them.  The robot arms could just reach out and grab a unit and attach to one of the nodes.   Remove the goods, fill with trash and put back on the dispenser bus.   When the bus is just trash, un-grapple and de-orbit.

It would be sort of like a giant vending machine.   A soft version with giant baggies and adapters would be an analogue of a box of trash bags.

That would be 53 tons of bus and non-perishables.  Sounds reasonable to this taxpayer.
 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: S.Paulissen on 04/29/2015 06:57 PM
It sounds good until you see the billions of dollars of R&D factored in, to save a little money on launch costs and increased exposure to loss on a single launch failure.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dror on 05/10/2015 07:36 PM
Do you guys think they will develop a methane Merlin?  If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?
I have read about it here several times.
In general there's methan Merlin (gas generator) and there's mini Raptor (staged combustion) and neither seems favored here.
Try reading :
http://forum.nasaspaceflight.com/index.php?topic=36508.0
http://forum.nasaspaceflight.com/index.php?topic=36621.0

And the best one -
http://forum.nasaspaceflight.com/index.php?topic=35533.0

This place is endless.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Hyperion5 on 05/10/2015 08:39 PM
Do you guys think they will develop a methane Merlin?  If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?

They might, though if you're going to go "all-methalox", you generally want a big increase in performance to compensate for the rocket's increased dry mass and production costs.  That's why I would suggest something like the following:

Detailed figures on both Falcon 9-M & Falcon Heavy-M below:
RocketFalcon 9-MFalcon Heavy-M (cross-feed)
Payload to LEO24.93 mt78.16 mt
Gross Mass446 mt1262.99 mt
Diameter3.66 m3.66 m x 3
SI Gross Mass358.47 mt763.77 mt
SI Propellant Mass 335.06 mt716.94 mt
SI Engines9xMini-Raptor27xMini-Raptor
SI SL Thrust576 tf1728 tf
SI Vac Thrust651.4 tf1954.2 tf
SI Engine Isp321/363321/363
SII Gross Mass60.90 mt358.47 mt
SII Propellant Mass56.80 mt335.06 mt
SII SL  ThrustN/A576 tf
SII Vac Thrust70 tf651.4 tf
SII Engine Isp380321/363
SIII Gross MassN/A60.90 mt
SIII Propellant MassN/A56.80 mt
SIII Vac ThrustN/A70 tf
SIII IspN/A380
PLF Mass1.70 mt1.70 mt
PLF separation time (sec.)220220
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Roy_H on 05/11/2015 12:54 AM
I know this has been extensively discussed before, but I couldn't be bothered to go through hundreds of pages to find it. Does anybody know (from SpaceX) what the proposed crossover architecture is? Was a consensus arrived at?

I have drawn a crude sketch of what I think it would be, all sharp corners would of course be smooth radii in actual design. I chose the single spool valve arrangement because it is the only one that results in a single tube without converging manifold for smooth propellant flow. The valve can be designed to be closing one port as it opens the other (I believe desirable in this situation, as opposed to closing one before opening the other).  This drawing depicts the valve and manifolding arrangement in the core booster for one fluid, it would be duplicated for RP1 and LOX and the side boosters would have their own shut-off valves. At launch the valves would be as shown, and just before side booster separation, they would move out so the fluid comes from the core tank. Valve action should be fast, a fraction of a second.

This arrangement allows the turbo pumps to pull the RP1 and LOX from the appropriate source with a minimum of extra bends or joints. As shown, one booster is connected to the 4 engines on the core closest to that side and the center engine is only fed from the core tank. This results in only 4 2-way valves in the core and a minimum of external connections with the side boosters. When throttling down, before staging, the center engine would throttle down first to conserve as much fuel in the center tank as possible. This arrangement provides for balanced fuel consumption from each side.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 05/11/2015 01:52 AM
Please review this pictures of the Angara-3 cross-feed preliminary design. Regrattably I don't speak Russian. It is different because this system is proposed at the tank level, while FH would be at the manifold level. I would also suggest that you look at the Booster Engine separation details, which is a bit more similar.
One issue you have is that you interrupt the flow of propellant with the spool valve. You need a a system that give priority to the propellant from the boosters, but won't interrupt the flow on separation, and then you need a one-way valve to avoid losing the propellant at separation. You'd also need a one way valve on the incoming pipes from the the core tank, since the boosters would probably need to supply a higher head pressure and thus you need to avoid a retro flow.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BobHk on 05/11/2015 03:45 AM
Please review this pictures of the Angara-3 cross-feed preliminary design. Regrattably I don't speak Russian. It is different because this system is proposed at the tank level, while FH would be at the manifold level. I would also suggest that you look at the Booster Engine separation details, which is a bit more similar.
One issue you have is that you interrupt the flow of propellant with the spool valve. You need a a system that give priority to the propellant from the boosters, but won't interrupt the flow on separation, and then you need a one-way valve to avoid losing the propellant at separation. You'd also need a one way valve on the incoming pipes from the the core tank, since the boosters would probably need to supply a higher head pressure and thus you need to avoid a retro flow.

If no one can find a translated copy i'll ask my neighbor if she can translate.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Roy_H on 05/11/2015 04:38 AM
Please review this pictures of the Angara-3 cross-feed preliminary design.

Well I disagree with your comments about shortcomings with my design, I am glad you posted the Angara pictures. Without understanding Russian, it is clear that tank-to-tank cross flow is viable (which I didn't think it was). Clearly by pressurizing the outboard booster tanks and not the central ones, sufficient fuel will flow from the outboard tanks to the central ones to power the central engine. The diagram shows the central tanks remaining completely full.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 05/11/2015 09:54 AM
Do you guys think they will develop a methane Merlin?  If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?

They might, though if you're going to go "all-methalox", you generally want a big increase in performance to compensate for the rocket's increased dry mass and production costs.  That's why I would suggest something like the following:

FWIW, I've long favoured a Falcon Hybrid, with a kerolox core (because RP1 performs better as an atmospheric fuel) and LCH4 in the upper stage (to get better ISP for BLEO insertion burns).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 05/12/2015 12:58 AM
Do you guys think they will develop a methane Merlin?  If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?

They might, though if you're going to go "all-methalox", you generally want a big increase in performance to compensate for the rocket's increased dry mass and production costs.  That's why I would suggest something like the following:

FWIW, I've long favoured a Falcon Hybrid, with a kerolox core (because RP1 performs better as an atmospheric fuel) and LCH4 in the upper stage (to get better ISP for BLEO insertion burns).
The only reason you'd prefer RP1 is bulk density, but CH4/O2 is pretty nearly the same bulk density, actually. ~830kg/m^3 vs 1030 for kerolox and 360 for hydrolox.

The benefit of higher Isp overwhelms the benefit in bulk density, and heck CH4 is actually cheaper. Once you have a high performance methane/LOx engine you might as well go for it. A hybrid wouldn't get you better performance but would net you higher operational costs.

...I admit it makes a little sense to push up Falcon Heavy performance in the interim before BFR/MCT, but starting from a clean-sheet for both, methane/LOx makes more sense than a hybrid would.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 05/12/2015 02:15 PM
IF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 05/12/2015 02:47 PM
IF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?

Please see Hyperion5's post here (http://forum.nasaspaceflight.com/index.php?topic=36806.msg1372522#msg1372522).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 05/12/2015 06:18 PM
Wow.  That is a fairly large increase.  24.9 tons on Falcon 9 and 78.1 on Falcon H (with crossfeed).  Without crossfeed would probably be about 65 tons to LEO.  Seems to me they should do that.  The MCT could benefit from the lower powered engines for landing on Mars with only 40% of earths gravity.  They could also benefit by being able to launch satelites to higher orbits.  Most of the same tooling for making Falcon 9 and Falcon H can be used.  The only change I see is a longer methane tank and a shorter oxygen tank than the kerolox version.  The other would be a turbopump issue for the methane vs kerosene.  Plumbing might be little different diameter.  Also, methane is only a few degrees different in liquid form than lox, so equipment would be almost identical to handle both, not like the super cold hydrogen. 

Sorry I missed that the first time. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Owlon on 05/12/2015 06:19 PM
IF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?

Please see Hyperion5's post here (http://forum.nasaspaceflight.com/index.php?topic=36806.msg1372522#msg1372522).

That assumes replacing the gas generator Merlin with a "mini Raptor" methane staged combustion engine that has equal thrust to Merlin. Replacing the current Merlin with an equivalent gas generator methane engine would probably give you a small decrease in performance, since methane's ~20% lower bulk density will have a slightly larger impact than the ~4% increase in ISP you get. There are some advantages to switching to methane, but you really need an entirely new high performance engine to make a big difference.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 05/12/2015 08:33 PM
Please review this pictures of the Angara-3 cross-feed preliminary design.

Well I disagree with your comments about shortcomings with my design, I am glad you posted the Angara pictures. Without understanding Russian, it is clear that tank-to-tank cross flow is viable (which I didn't think it was). Clearly by pressurizing the outboard booster tanks and not the central ones, sufficient fuel will flow from the outboard tanks to the central ones to power the central engine. The diagram shows the central tanks remaining completely full.
Instead of a spool 3-way valve, you should use two on/off valves (one for in-core tank, one for booster incoming flow), a one way valve after the booster incoming flow valve to close the circuit after separation. And another one-way valve before the in core flow valve to avoid back flow. And somehow design the piping in such a way that it leaves no bubbles (or ad a heavy gas trap). Also, you should make sure that the process of opening one valve and close the other can comply with two requirements: no head pressure drop below the minimum engine specified AND generates no turbulence that may end up in cavitation.
I don't know what's your experience with cryo liquids, but it's not that easy (but totally doable). Just not possible with a 3-way valve (which are specially heavy for big diameter piping.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 05/12/2015 11:15 PM
IF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?

Please see Hyperion5's post here (http://forum.nasaspaceflight.com/index.php?topic=36806.msg1372522#msg1372522).

That assumes replacing the gas generator Merlin with a "mini Raptor" methane staged combustion engine that has equal thrust to Merlin. Replacing the current Merlin with an equivalent gas generator methane engine would probably give you a small decrease in performance, since methane's ~20% lower bulk density will have a slightly larger impact than the ~4% increase in ISP you get. There are some advantages to switching to methane, but you really need an entirely new high performance engine to make a big difference.

Agreed.  They -could- do it, but I don't know that they will.  I think these latest "v1.2" Falcon upgrades will make F9 and FH pretty much cover the commercial and goverment sat market with full reusability.  (Maybe an expended FH core for a rare big DoD bird).

All their pads will be set up for only kerolox, and they've invested a lot into the F9 cores as they will now be, as well as the latest itteration of Merlin.  If they every do entertain a methalox version of Merlin, or a "mini-raptor", I can't see it being for quite some time.  It's not needed performance wise because they will already be hitting their market goals, RP-1 isn't really significantly more expensive than LCH4 I don't think, I think the F9 core is already at the limit for what can be transported on the roadways...methalox would likely need to be a little longer or wider, and their R&D budgets are better spent on MCT and associated developments.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: groundbound on 05/13/2015 05:16 AM
Note that a lot of those conclusions are partly because of the severe US  size restraints. Though this goes against what we know of SpaceX' plans, there is a confluence of changes that they might undertake some years down the road.

Larger "hammerhead" FH upper stage + methalox  US + early start of BFR factory + methane infrastructure at future BFR pad. 

This would let them spread out some of the capital intensive activities eventually required for BFR and yield a little extra revenue during final BFR/MCT development.  Shipping a single engine and other subassemblies from Hawthorne for final US assembly is not a dealbreaker. And a few years down the road, an FH variant with a very high energy upper stage that is limited to just one of their pads might give them some additional capability without being too much of a diversion of capital and focus.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 05/13/2015 05:51 AM
I don't think they will do a methalox version of Falcon. If and when it looks like competition (Blue Origin) comes up with a competetive fully reusable launch archictecture they may built a new intermediate archictecture. Something like a 9 (or 7) Raptor first stage with a single Raptor upper stage. That would cover the whole range of payloads the Falcon family can now fly. Bigger diameter and not road transportable won't matter much with a fully reusable system.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: baldusi on 05/13/2015 12:43 PM
Do you guys think they will develop a methane Merlin?  If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?

They might, though if you're going to go "all-methalox", you generally want a big increase in performance to compensate for the rocket's increased dry mass and production costs.  That's why I would suggest something like the following:

Detailed figures on both Falcon 9-M & Falcon Heavy-M below:
RocketFalcon 9-MFalcon Heavy-M (cross-feed)
Payload to LEO24.93 mt78.16 mt
Gross Mass446 mt1262.99 mt
Diameter3.66 m3.66 m x 3
SI Gross Mass358.47 mt763.77 mt
SI Propellant Mass 335.06 mt716.94 mt
SI Engines9xMini-Raptor27xMini-Raptor
SI SL Thrust576 tf1728 tf
SI Vac Thrust651.4 tf1954.2 tf
SI Engine Isp321/363321/363
SII Gross Mass60.90 mt358.47 mt
SII Propellant Mass56.80 mt335.06 mt
SII SL  ThrustN/A576 tf
SII Vac Thrust70 tf651.4 tf
SII Engine Isp380321/363
SIII Gross MassN/A60.90 mt
SIII Propellant MassN/A56.80 mt
SIII Vac ThrustN/A70 tf
SIII IspN/A380
PLF Mass1.70 mt1.70 mt
PLF separation time (sec.)220220
Have Dimitry done any simulation an an Falcon 9 v1.2 M? I suspect it might cover Delta IV Heavy payloads in expendable mode.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Graham on 05/13/2015 08:21 PM
In this video from the Planetary Society:  https://www.youtube.com/watch?v=kDBzRa9RzfM 
Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Roy_H on 05/13/2015 08:56 PM
Please review this pictures of the Angara-3 cross-feed preliminary design.

Well I disagree with your comments about shortcomings with my design, I am glad you posted the Angara pictures. Without understanding Russian, it is clear that tank-to-tank cross flow is viable (which I didn't think it was). Clearly by pressurizing the outboard booster tanks and not the central ones, sufficient fuel will flow from the outboard tanks to the central ones to power the central engine. The diagram shows the central tanks remaining completely full.
Instead of a spool 3-way valve, you should use two on/off valves (one for in-core tank, one for booster incoming flow), a one way valve after the booster incoming flow valve to close the circuit after separation. And another one-way valve before the in core flow valve to avoid back flow. And somehow design the piping in such a way that it leaves no bubbles (or ad a heavy gas trap). Also, you should make sure that the process of opening one valve and close the other can comply with two requirements: no head pressure drop below the minimum engine specified AND generates no turbulence that may end up in cavitation.
I don't know what's your experience with cryo liquids, but it's not that easy (but totally doable). Just not possible with a 3-way valve (which are specially heavy for big diameter piping.

Well, I didn't want to get into a spitting match with you, but here goes. If you use separate valves as you propose then you will have to have manifolding where the two pipes from the valves to the turbo pumps join, thus creating an edge that will cause turbulence and a dead-end tube. You specifically said "somehow" this must be avoided. Using one spool valve is the answer to this problem. The spool valve allows the flow from tank to turbo pumps to be continuous and free of sharp bends (of the type common in one-way valves). Why are you concerned about back flow from outer tanks to central tank? First this is extremely unlikely and could only happen during the less than 1 second transition time of valve actuation. second if some were to get from the external to the core, that would be a good thing wouldn't it? At time of transition,  I would expect all engines to be throttled down for booster separation so maximum flow is not required, but as one path is being closed, from the external tanks the other path to the central tank is opening, so at no time are the turbo tanks pumps starved. During this transition time there will be significant flow from the external tanks with high inertia, I think concerns of the flow starting up from the central tank being strong enough to overcome the turbo pump requirements and then push against the high inertia momentum is near impossible. Adding a check valve is just needless complication as the path will be closed by the spool valve, and as I said before it is difficult to design a check valve that does not increase turbulence. Even if the impossible happened, how much fuel would be lost in that fraction of a second?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: rst on 05/13/2015 09:21 PM
In this video from the Planetary Society ...
Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?

FWIW, references to FH start at about the 3:30 mark, and include CG video.  More details on the mission are at the kickstarter page:

https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft

which mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.

One presumes that these are secondary payloads; nothing here says much specific about the primary, though.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Graham on 05/13/2015 11:07 PM
In this video from the Planetary Society ...
Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?

FWIW, references to FH start at about the 3:30 mark, and include CG video.  More details on the mission are at the kickstarter page:

https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft

which mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.

One presumes that these are secondary payloads; nothing here says much specific about the primary, though.
During the Light Sail reveal event last year it was stated that PROX- 1 would be a secondary payload. I was under the impression that SpaceX was still aiming to fly the demo mission by the end of 2015, but Mr. Nye states that Light Sail will fly on the first flight of the FH in 2016. I'm just wondering if anyone here has heard if the demo mission has shifted to the right or if Mr. Nye mispoke.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: eriblo on 05/13/2015 11:27 PM
In this video from the Planetary Society ...
Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?

FWIW, references to FH start at about the 3:30 mark, and include CG video.  More details on the mission are at the kickstarter page:

https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft

which mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.

One presumes that these are secondary payloads; nothing here says much specific about the primary, though.
During the Light Sail reveal event last year it was stated that PROX- 1 would be a secondary payload. I was under the impression that SpaceX was still aiming to fly the demo mission by the end of 2015, but Mr. Nye states that Light Sail will fly on the first flight of the FH in 2016. I'm just wondering if anyone here has heard if the demo mission has shifted to the right or if Mr. Nye mispoke.
He didn't misspeak, he just left out "operational" (as stated in the Kickstarter campaign description and likely elsewhere).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 05/13/2015 11:31 PM
Love Bill Nye, but I don't hang on every word he says when it's about something very technical.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Graham on 05/13/2015 11:38 PM
In this video from the Planetary Society ...
Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?

FWIW, references to FH start at about the 3:30 mark, and include CG video.  More details on the mission are at the kickstarter page:

https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraft

which mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.

One presumes that these are secondary payloads; nothing here says much specific about the primary, though.
During the Light Sail reveal event last year it was stated that PROX- 1 would be a secondary payload. I was under the impression that SpaceX was still aiming to fly the demo mission by the end of 2015, but Mr. Nye states that Light Sail will fly on the first flight of the FH in 2016. I'm just wondering if anyone here has heard if the demo mission has shifted to the right or if Mr. Nye mispoke.
He didn't misspeak, he just left out "operational" (as stated in the Kickstarter campaign description and likely elsewhere).
Thanks, I must have missed that in the Kickstarter description. I figured that that was what he meant, but I wasn't sure.

Love Bill Nye, but I don't hang on every word he says when it's about something very technical.
I would agree with that, but I do love his enthusiasm
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: DanseMacabre on 05/20/2015 06:04 PM
http://spacenews.com/viasat-sees-falcon-heavy-as-pacing-item-in-growth-plans/ (http://spacenews.com/viasat-sees-falcon-heavy-as-pacing-item-in-growth-plans/)

Seems to also indicate a FH first flight in 2016. Additionally that's a blimmin' aspirational manifest! Launching a commercial payload so soon following the inaugural flight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: paulcpaulc on 05/31/2015 10:21 PM
The recent F9H video showed black legs and leg nacelles...
https://www.youtube.com/watch?v=4Ca6x4QbpoM

Is this extra thermal protection than we have had to date?

Does anyone know when we might see this leg configuration for the first time? Perhaps on a "regular" F9 launch soon?

Thanks,
Paul.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 06/01/2015 04:53 AM
The SpaceX illustrations of their rockets always have black trim---look at interstage of the F9 on spacex.com for example---but the flying versions have been all-white.  Dunno why, it's a (very minor) mystery.

I'd expect the actual FH to be all white as well.  Note that the legs of the illustration at http://www.spacex.com/falcon-heavy are all-white---but with the same odd never-actually-seen-on-a-real-rocket black interstage as they illustrate on the F9.

I think they are using black to indicate "composite construction", not implying that the actual rocket would be painted black in that way.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deruch on 06/01/2015 05:23 AM
The recent F9H video showed black legs and leg nacelles...
Is this extra thermal protection than we have had to date?
Does anyone know when we might see this leg configuration for the first time? Perhaps on a "regular" F9 launch soon?

Thanks,
Paul.

I always assumed that SpaceX intentionally used this "irregular" coloring scheme to easily differentiate between actual pictures and renderings/models.  Though I like cscott's notion that it might represent composites, too.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kabloona on 06/01/2015 05:02 PM
The recent F9H video showed black legs and leg nacelles...
Is this extra thermal protection than we have had to date?
Does anyone know when we might see this leg configuration for the first time? Perhaps on a "regular" F9 launch soon?

Thanks,
Paul.

I always assumed that SpaceX intentionally used this "irregular" coloring scheme to easily differentiate between actual pictures and renderings/models.  Though I like cscott's notion that it might represent composites, too.

Changing to a black color scheme for the legs and aft end of the stage might make sense once re-use becomes standard procedure. We've seen how the aft end gets sooted/scorched during retro burn, and black paint might cover scorch marks up for reuse better than white paint.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Roy_H on 06/01/2015 09:26 PM
This is pure speculation on my part, but I was wondering if SpaceX might take advantage of the demo launch of Falcon Heavy to launch a Dragon 2 (mostly complete but without support for humans) to try a propulsive landing at Vandenberg?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: 411rocket on 06/02/2015 12:04 AM
This is pure speculation on my part, but I was wondering if SpaceX might take advantage of the demo launch of Falcon Heavy to launch a Dragon 2 (mostly complete but without support for humans) to try a propulsive landing at Vandenberg?

A retro fitted, previously flown Dragon 1, would make more sense, than a Dragon 2. This is assuming, the Dragonfly tests, have progressed far enough, to give it a try.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Zed_Noir on 06/02/2015 02:52 AM
This is pure speculation on my part, but I was wondering if SpaceX might take advantage of the demo launch of Falcon Heavy to launch a Dragon 2 (mostly complete but without support for humans) to try a propulsive landing at Vandenberg?

A retro fitted, previously flown Dragon 1, would make more sense, than a Dragon 2. This is assuming, the Dragonfly tests, have progressed far enough, to give it a try.

Hmm, the Dragon 1 don't have Super-Dracos or do propulsive landings.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Coastal Ron on 06/02/2015 03:02 AM
This is pure speculation on my part, but I was wondering if SpaceX might take advantage of the demo launch of Falcon Heavy to launch a Dragon 2 (mostly complete but without support for humans) to try a propulsive landing at Vandenberg?

I'm sure they've thought of it.  Could re-fly one of their once-used Cargo Dragons, maybe around the Moon?  That would inspire a lot of conversations...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: 411rocket on 06/02/2015 03:26 AM

A retro fitted, previously flown Dragon 1, would make more sense, than a Dragon 2. This is assuming, the Dragonfly tests, have progressed far enough, to give it a try.

Hmm, the Dragon 1 don't have Super-Dracos or do propulsive landings.

The pad abort test vehicle, was a modified Dragon 1, so it can be done. Check the interior pics, of the pad abort dragon interior pressure hull & the interior of the Dragon 2 unveiling for visual on differences.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: CraigLieb on 06/04/2015 05:35 PM
...
Changing to a black color scheme for the legs and aft end of the stage might make sense once re-use becomes standard procedure. We've seen how the aft end gets sooted/scorched during retro burn, and black paint might cover scorch marks up for reuse better than white paint.

Changing to a black color scheme has the possible benefit not painting the composite legs which could be carbon fiber, saving production time and weight. Does this increase performance and the payload to orbit?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: matthewkantar on 06/04/2015 06:44 PM
I am not sure about modern carbon composites, but as recently as 15 years ago dark colors were not allowed on composite structures to keep them from over heating in the harshest solar heating situations. Since some current carbon fiber is baked, maybe this isn't an issue. Any know if I can paint my 787 flat black?

Matthew
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: e of pi on 06/04/2015 08:42 PM
Changing to a black color scheme has the possible benefit not painting the composite legs which could be carbon fiber, saving production time and weight. Does this increase performance and the payload to orbit?
In theory, any weight savings increases maximum performance, but not necesarily meaningfully. If there's 100 kg of paint on the legs (and we know they only mass about 2000 kg total, so it's probably far less), then the improvement in maximum payload would be about a tenth of that--the rule of thumb is something like ten kg off the first stage for one extra kg of payload. Thus, even in this crazy "hundred kg of paint" case, you're only gaining 10kg of maximum payload out of tons, when many of F9 v1.1's launches so far have left significant room on the table below the maximum payload.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: CraigLieb on 06/05/2015 03:11 PM
Changing to a black color scheme has the possible benefit not painting the composite legs which could be carbon fiber, saving production time and weight. Does this increase performance and the payload to orbit?
In theory, any weight savings increases maximum performance, but not necesarily meaningfully. If there's 100 kg of paint on the legs (and we know they only mass about 2000 kg total, so it's probably far less), then the improvement in maximum payload would be about a tenth of that--the rule of thumb is something like ten kg off the first stage for one extra kg of payload. Thus, even in this crazy "hundred kg of paint" case, you're only gaining 10kg of maximum payload out of tons, when many of F9 v1.1's launches so far have left significant room on the table below the maximum payload.
Then the cost factor of not having to paint the legs, inspecting the paint, repair scratches, rework,  clean or re-paint the legs on reuse, etc may be the biggest benefit if they choose to 'go commando'.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wxmeddler on 06/05/2015 04:38 PM
This is pure speculation on my part, but I was wondering if SpaceX might take advantage of the demo launch of Falcon Heavy to launch a Dragon 2 (mostly complete but without support for humans) to try a propulsive landing at Vandenberg?

I'm sure they've thought of it.  Could re-fly one of their once-used Cargo Dragons, maybe around the Moon?  That would inspire a lot of conversations...
They could use the opportunity to show off the capabilities of the Science Dragon initiative they've been pushing. I don't know if they have a spare Dragonv2 laying around that they could throw on top but I would assume that you could easily load one with cameras, radiation sensors, etc. and make a trip around the moon without much issue and make SpaceX a household name for a week.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Sohl on 06/05/2015 05:46 PM
I am not sure about modern carbon composites, but as recently as 15 years ago dark colors were not allowed on composite structures to keep them from over heating in the harshest solar heating situations.

Matthew

An F9R booster should not be in space very long!  And it should enjoy a nice cooling breeze fairly soon on the way down.  ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: CJ on 06/27/2015 11:12 AM

I noticed something in Jeffry Thornburg's testimony in Congress that I thought might be relevant for this thread;
Quote
With the Falcon Heavy, which we plan to launch later this year, fly three times next year and certify soon thereafter, SpaceX will be able to launch 100 percent of the DOD's manifest.

Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.

The full testimony is here;
http://spaceref.com/news/viewsr.html?pid=47400
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: AncientU on 06/27/2015 12:24 PM
Four scheduled launches of the world's soon-to-be largest rocket in first year (or two)... that will be something to watch!  Did I mention reusable?  Three landing attempts each launch!

Delta IV Heavy (half the payload, three times the price) has only launched eight times in its eleven year lifetime. 

Mr. Thornburg confirmed that they would self-fund the first launch. 
We still don't know the payload/destination, do we?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Mader Levap on 06/27/2015 05:26 PM
Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.
As Dilbert's boss said (http://dilbert.com/strip/2001-11-19), optimism is not crime.

I will believe about FH launch in 2015 when I will see it, not picosecond earlier.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wannamoonbase on 06/27/2015 11:50 PM
Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.
As Dilbert's boss said (http://dilbert.com/strip/2001-11-19), optimism is not crime.

I will believe about FH launch in 2015 when I will see it, not picosecond earlier.

Agreed, if it's even vertical in Texas or Florida this year I'll be happy.

Given the F9 flight rate are we even sure they can build cores quick enough?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: obi-wan on 06/28/2015 12:36 AM
Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.
As Dilbert's boss said (http://dilbert.com/strip/2001-11-19), optimism is not crime.

I will believe about FH launch in 2015 when I will see it, not picosecond earlier.

Agreed, if it's even vertical in Texas or Florida this year I'll be happy.

Given the F9 flight rate are we even sure they can build cores quick enough?

From a SpaceX talk by upper-level management I was at last week, they said their current capacity is 18 cores/year, but they're ramping up for 40/year.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oldAtlas_Eguy on 06/28/2015 01:10 AM
Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.
As Dilbert's boss said (http://dilbert.com/strip/2001-11-19), optimism is not crime.

I will believe about FH launch in 2015 when I will see it, not picosecond earlier.

Agreed, if it's even vertical in Texas or Florida this year I'll be happy.

Given the F9 flight rate are we even sure they can build cores quick enough?

From a SpaceX talk by upper-level management I was at last week, they said their current capacity is 18 cores/year, but they're ramping up for 40/year.

Since the max usage for this year looks to be 14 cores (11 F9 and 1 FH) If they build at the max current rate for 2 years at 18 each year that means that there would be 22 cores at least available for next year or 3 FH and 13 F9 launches. Now add in eventual F9 reuse and launch rate could be higher.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 06/28/2015 01:17 AM
Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.
As Dilbert's boss said (http://dilbert.com/strip/2001-11-19), optimism is not crime.

I will believe about FH launch in 2015 when I will see it, not picosecond earlier.

Agreed, if it's even vertical in Texas or Florida this year I'll be happy.

Given the F9 flight rate are we even sure they can build cores quick enough?

From a SpaceX talk by upper-level management I was at last week, they said their current capacity is 18 cores/year, but they're ramping up for 40/year.

Since the max usage for this year looks to be 14 cores (11 F9 and 1 FH) If they build at the max current rate for 2 years at 18 each year that means that there would be 22 cores at least available for next year or 3 FH and 13 F9 launches. Now add in eventual F9 reuse and launch rate could be higher.

I took that very differently, I am presuming 18 cores trailing 12 months and somewhere between 18 and 40 for the next 12 months (also presuming 13 this year including the first FH).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wannamoonbase on 06/28/2015 02:17 AM
Obi-wan, thanks for the info.  18 cores is impressive.

nareck, if they can do 40 doesn't mean they are going to blindly produce cores.  At some point they will have to match production to sales.

I do get giddy at the idea of 360 Merlin 1D's per year.  Amazing.

Edit: The change to the v1.2 configuration has to have had some interruption.  But there shouldn't be too much more to tweak after the v1.2 changes, the vehicle evolution seems to be almost complete.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: fthomassy on 06/28/2015 02:42 AM
I do get giddy at the idea of 360 Merlin 1D's per year.  Amazing.
400 if you think stage two counts ... and it should.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: newpylong on 07/01/2015 07:14 PM
Four scheduled launches of the world's soon-to-be largest rocket in first year (or two)... that will be something to watch!  Did I mention reusable?  Three landing attempts each launch!

Delta IV Heavy (half the payload, three times the price) has only launched eight times in its eleven year lifetime. 

Mr. Thornburg confirmed that they would self-fund the first launch. 
We still don't know the payload/destination, do we?

And launched 11 years before Falcon Heavy (and counting.) What's your point?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jim on 07/01/2015 07:38 PM

 Three landing attempts each launch!

Delta IV Heavy (half the payload, three times the price) has only launched eight times in its eleven year lifetime. 


A. the payload is greater to GSO which is was designed for and not LEO
b.  That should be a hint at the small market for it
c.  Three times the cores to blow up
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: LastStarFighter on 07/01/2015 07:53 PM

 Three landing attempts each launch!

Delta IV Heavy (half the payload, three times the price) has only launched eight times in its eleven year lifetime. 


A. the payload is greater to GSO which is was designed for and not LEO
b.  That should be a hint at the small market for it
c.  Three times the cores to blow up

They also have to launch that many FH's to cover the performance spectrum. ULA has enough versatility in their single sticks that they don't require the triple core as often as SpaceX.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JH on 07/01/2015 07:57 PM
Sounds to me as if they are still on track for a FH flight this year. It might slop, of course, but IMHO they wouldn't have said this year if they knew it was false.

For what it's worth, while I was talking to some SpaceX employees a few days ago, they mentioned that the Falcon Heavy demo flight would be in Q1 or Q2 of 2016. In light of Sunday's events, who knows if this still holds true.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ronsmytheiii on 07/20/2015 08:40 PM
NET Spring 2016

FH Spring next year.

http://forum.nasaspaceflight.com/index.php?topic=37739.340
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: yg1968 on 07/20/2015 09:47 PM
NET Spring 2016

FH Spring next year.

http://forum.nasaspaceflight.com/index.php?topic=37739.340

He said Spring and then added maybe April 2016.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lumina on 07/21/2015 07:11 PM
NET Spring 2016

FH Spring next year.

http://forum.nasaspaceflight.com/index.php?topic=37739.340

He said Spring and then added maybe April 2016.

Re: CRS-7 - it's mind boggling to think that the arrival of the first humans on Mars was likely pushed back further by 6 more months because a few billion atoms of iron, carbon, chromium and whatnot were in the wrong place at the wrong time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BusterSky on 07/21/2015 08:37 PM
My 0.02$ : Space X is keeping a low profile because it would seem too audacious to announce FH after the CRS 7 kaboom.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oldAtlas_Eguy on 07/21/2015 09:16 PM
Actually I think it is a minor item of core rework. Both 1st and US use the same struts. Existing cores must be reworked before launch. Paying flights have priority. A 6 month burp in the production schedule of cores until the build rate is back up and capable of producing more than what is used creating a surplus of cores going into storage for use at a later higher launch rate during the last 3Qs of 2016 and into 2017. Scheduled for 2016 are 4 CRS, ~6 GEO, 3-4 FH, 4-5 Iridium, and couple other odds and ends LEO (DV2 DM-1 is one) for total number of cores possibly needed in 2016 of up to 29 cores.

Maybe reusability will work out and the FH cores will be reused so only one set is needed of 3 cores instead of the 12 to do 4 FH flights.

Another item is maybe they want the landing to be proven so the FH Demo can RTLS its cores. Since the next opportunity for a landing test is NET late Sept that 6 month slip may just barely be enough time to be able to have them do RTLS.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: solartear on 07/21/2015 10:41 PM
Re: CRS-7 - it's mind boggling to think that the arrival of the first humans on Mars was likely pushed back further by 6 more months because a few billion atoms of iron, carbon, chromium and whatnot were in the wrong place at the wrong time.

Nobody is going to Mars on Falcon Heavy, and there is a 2 year transit window, so 0 or 2 years. In could have a small impact on Bigelow's efforts, or a lunar station, if one were in progress.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wannamoonbase on 07/22/2015 12:59 AM
My 0.02$ : Space X is keeping a low profile because it would seem too audacious to announce FH after the CRS 7 kaboom.

My two cents, it's a very large complex vehicle and they need more time to develop, build and test it and the new launch pad.  They have many tons of work to do before that bird flys.

9 months (or so) seems like a long time to us, but those working on it will undoubtedly feel time pressure.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 07/22/2015 04:35 AM
Up to now they did not have pressure to get FH flying. However now that they are in direct competition for DOD flights I am sure they want to get FH flying ASAP. But return to flight and getting their manifest done is an even more pressing need at the moment.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 07/22/2015 03:10 PM
From the teleconference (http://shitelonsays.com/transcript/elon-musk-talks-failed-crs-7-dragon-mission-2015-07-20):
Quote
42:15 Stephen Clark: And the Falcon Heavy?

42:22 Elon Musk: Given our focus on Falcon 9, we've deprioritized the Falcon Heavy to probably launch in the spring next year. So maybe April or so.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Billium on 07/22/2015 11:03 PM
This blog http://www.planetary.org/blogs/jason-davis/2015/20150720-broken-bottle-strut-falcon.html from the planetary society suggests their lightsail sat had been scheduled to launch on the 1st operational FH flight in fall 2016. Given the delay of the FH test flight from Q4 2015 to NET April 2016, I would assume the first FH operational flight will also slip, maybe Q4 2016? I think they had 3 FH operational flights in the plan for 2016, I don't see how they can make that happen.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wannamoonbase on 07/23/2015 03:18 AM
Guckyfan, there has been pressure on the FH for years now.  It has slid lots and there are paying clients that want their payloads scheduled.  Not to mention the SpaceX sales staff who will have better luck selling a vehicle once it's flying.

Cscott, Elon's statement could be true.  But it's also something that could have been guessed.  It's almost August and there isn't a FH in Texas and LC39A isn't ready.  They need the time and should Probably include a reference to F9 v1.2 as far as we know that baby isn't confirmed ready for prime time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/02/2015 11:56 PM
SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: GalacticIntruder on 09/03/2015 12:55 AM
Strange they still offer Cross-feed for over 45mT. I thought they abandoned the complexity of cross-feed and V1.2 would replace it for performance. If that is not true, then they are still maxed out at 45mT not 53mT. Seems disingenuous for me if a buyer needed it, and it won't be available.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cscott on 09/03/2015 01:14 AM
They never said "abandoned", they said "deferred".  The difference is only significant after a customer steps up.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: yg1968 on 09/03/2015 02:37 AM
Here is an article on the FH:
http://spacenews.com/first-falcon-heavy-launch-scheduled-for-spring/
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 09/03/2015 06:27 AM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nimbostratus on 09/03/2015 10:10 AM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin

What I see is uniform boosters/core compared to original booster/cores with different length.
I do not see any difference in the interstage or the upper stage.
Can anyone verify?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Bargemanos on 09/03/2015 10:58 AM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin

It indeed does looks a bit longer.
Also, the leg's seem shorter and the center engine alignment is different. This could be just the rendering ofcourse.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/03/2015 03:32 PM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin

I think the difference is small enough to be explained by the old image having less accurate proportions and details. I don't think the interstage has grown in size, but I could be wrong. Here is an image with the interstages highlighted in red:


Also, the leg's seem shorter and the center engine alignment is different. This could be just the rendering ofcourse.

I think most of that might just be due to more details and better accuracy in the new version. I remember trying to overlay the old F9 images over pictures of the actual v1.1, and finding that the proportions were slightly off.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dorkmo on 09/03/2015 04:19 PM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin

It indeed does looks a bit longer.
Also, the leg's seem shorter and the center engine alignment is different. This could be just the rendering ofcourse.

it looks to me like the previous render was displayed in parallel projection, while the new one is displayed in perspective from a long viewing distance. i think thats whats making the center engine look different.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oldAtlas_Eguy on 09/03/2015 05:46 PM
No C/F                                                  With C/F         
FHRv1.1   FHv1.1   FHRv1.2   FHv1.2   FHRv1.1   FHv1.1   FHRv1.2   FHv1.2
36           44.3        41           50.5        43           53           49           60.5


These values although very rough estimate numbers shows the relationships between the original FHv1.1 versions capabilities and the newer FHv1.2 versions capabilities. [Versions are [R][C/F:woC/F], four in all for each v.

The R versions assume the same landing of booster RTLS and center core ASDS landing downrange.

The conclusion is that unless you need something with a capability of > 49mt then a reusable configuration would work just fine. Even woC/F you get about 41mt reusable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/03/2015 06:24 PM
No C/F                                                  With C/F         
FHRv1.1   FHv1.1   FHRv1.2   FHv1.2   FHRv1.1   FHv1.1   FHRv1.2   FHv1.2
36           44.3        41           50.5        43           53           49           60.5


These values although very rough estimate numbers shows the relationships between the original FHv1.1 versions capabilities and the newer FHv1.2 versions capabilities. [Versions are [R][C/F:woC/F], four in all for each v.

The R versions assume the same landing of booster RTLS and center core ASDS landing downrange.

The conclusion is that unless you need something with a capability of > 49mt then a reusable configuration would work just fine. Even woC/F you get about 41mt reusable.

Did you run your centre core expendable but not crossfed models with something like the following centre core firing engine profile (note time in seconds):

L-2 to L+13 9 centre core engines firing at 100% thrust (uses 8% of centre core fuel - 92% remaining)
L+13 to L+30 7 centre core engines firing at 100% thrust (uses 8% of centre core fuel - 83% remaining)
L+30 to L+60 4 centre core engines firing at 100% thrust (uses 7% of centre core fuel - 76% remaining)
L+60 to L+154 4 centre core engines firing at 70% thrust (uses 23% of centre core fuel - 53% remaining)
L+154 side boosters seperate with 20% fuel remaining in each
L+154 to 262 4 centre core engines firing at 100% thrust
L+262 to 479 2 centre core engines firing at 100% thrust
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oldAtlas_Eguy on 09/03/2015 06:49 PM
No C/F                                                  With C/F         
FHRv1.1   FHv1.1   FHRv1.2   FHv1.2   FHRv1.1   FHv1.1   FHRv1.2   FHv1.2
36           44.3        41           50.5        43           53           49           60.5


These values although very rough estimate numbers shows the relationships between the original FHv1.1 versions capabilities and the newer FHv1.2 versions capabilities. [Versions are [R][C/F:woC/F], four in all for each v.

The R versions assume the same landing of booster RTLS and center core ASDS landing downrange.

The conclusion is that unless you need something with a capability of > 49mt then a reusable configuration would work just fine. Even woC/F you get about 41mt reusable.

Did you run your centre core expendable but not crossfed models with something like the following centre core firing engine profile (note time in seconds):

L-2 to L+13 9 centre core engines firing at 100% thrust (uses 8% of centre core fuel - 92% remaining)
L+13 to L+30 7 centre core engines firing at 100% thrust (uses 8% of centre core fuel - 83% remaining)
L+30 to L+60 4 centre core engines firing at 100% thrust (uses 7% of centre core fuel - 76% remaining)
L+60 to L+154 4 centre core engines firing at 70% thrust (uses 23% of centre core fuel - 53% remaining)
L+154 side boosters seperate with 20% fuel remaining in each
L+154 to 262 4 centre core engines firing at 100% thrust
L+262 to 479 2 centre core engines firing at 100% thrust

As you point out optimizing the burn profile can change the payload amounts for the expendable FH.  My numbers are nothing more than a set of estimates showing the relationships of payloads capabilities between all of configurations. The values can be +-a few mt. So configurations within about 5% (~+-2.5mt) values are considered equal.

The new choices for payloads related to the configurations required in the FHv1.2 would be
<40 FHRv1.2woC/F
<50 FHRv1.2C/F
<60 FHv1.2

What I am trying to point out is that the goals for FH of 50mt can be done with a FHRv1.2C/F lowering the costs of that payload size class by $75M making flying with C/F almost the same cost as woC/F (each C/F booster costs $10M more to make) such that a FHRv1.2woC/F could be priced at as low as $50M and a FHRv1.2C/F as low as $60M.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/03/2015 06:59 PM
No C/F                                                  With C/F         
FHRv1.1   FHv1.1   FHRv1.2   FHv1.2   FHRv1.1   FHv1.1   FHRv1.2   FHv1.2
36           44.3        41           50.5        43           53           49           60.5


These values although very rough estimate numbers shows the relationships between the original FHv1.1 versions capabilities and the newer FHv1.2 versions capabilities. [Versions are [R][C/F:woC/F], four in all for each v.

The R versions assume the same landing of booster RTLS and center core ASDS landing downrange.

The conclusion is that unless you need something with a capability of > 49mt then a reusable configuration would work just fine. Even woC/F you get about 41mt reusable.

Did you run your centre core expendable but not crossfed models with something like the following centre core firing engine profile (note time in seconds):

L-2 to L+13 9 centre core engines firing at 100% thrust (uses 8% of centre core fuel - 92% remaining)
L+13 to L+30 7 centre core engines firing at 100% thrust (uses 8% of centre core fuel - 83% remaining)
L+30 to L+60 4 centre core engines firing at 100% thrust (uses 7% of centre core fuel - 76% remaining)
L+60 to L+154 4 centre core engines firing at 70% thrust (uses 23% of centre core fuel - 53% remaining)
L+154 side boosters seperate with 20% fuel remaining in each
L+154 to 262 4 centre core engines firing at 100% thrust
L+262 to 479 2 centre core engines firing at 100% thrust

As you point out optimizing the burn profile can change the payload amounts for the expendable FH.  My numbers are nothing more than a set of estimates showing the relationships of payloads capabilities between all of configurations. The values can be +-a few mt. So configurations within about 5% (~+-2.5mt) values are considered equal.

The new choices for payloads related to the configurations required in the FHv1.2 would be
<40 FHRv1.2woC/F
<50 FHRv1.2C/F
<60 FHv1.2

What I am trying to point out is that the goals for FH of 50mt can be done with a FHRv1.2C/F lowering the costs of that payload size class by $75M making flying with C/F almost the same cost as woC/F (each C/F booster costs $10M more to make) such that a FHRv1.2woC/F could be priced at as low as $50M and a FHRv1.2C/F as low as $60M.

Ok, but I don't think that C/F gives as much benefit as  you are conferring even with these numbers. Also I don't see using C/F with a recoverable centre core (you need to reserve enough propellant on the centre core to bring it back to re-entry speed) so the performance gain is minimal the big jump comes from disposing of the centre core at 6 to 7km/s (which you can approach without C/F).

My point is that I just don't think C/F will be implemented because of the minimal advantages it gives.

In the dollars per kg to LEO, I think FH3R (no C/F) wins. FH2R (centre core expendable no C/F) definitely wins in the dollars per kg to GTO, GSO, TLI, TMI.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Comga on 09/03/2015 07:23 PM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin

And modified, shorter legs
Core and boosters are now the same length
Changed booster front attach mechanism
No more visible horizontal seams on first stages
More detail on the fairings and exterior wiring and cameras
And...?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oldAtlas_Eguy on 09/03/2015 07:27 PM
nadreck
You are probably correct in that there may never be a plain FHC/F. If or when they get RTLS working FH is unlikely to ever fly a non -reusable configuration after that even if only the boosters are recovered. A C/F where the center core is expended would cost $25M more or a price as low as $85M. Those values of $90M in the NASA Moon return study for FH usage and costs starts to look like they may be closer to correct than we think. Maybe they got some probable pricing data from SpaceX for the FH2Rv1.2C/F configuration that could do what they specified for TLI.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TrevorMonty on 09/03/2015 08:39 PM
No C/F                                                  With C/F
FHRv1.1FHv1.1FHRv1.2FHv1.2FHRv1.1FHv1.1FHRv1.2FHv1.2
36           44.3        41           50.5        43           53           49           60.5


These values although very rough estimate numbers shows the relationships between the original FHv1.1 versions capabilities and the newer FHv1.2 versions capabilities. [Versions are [R][C/F:woC/F], four in all for each v.

The R versions assume the same landing of booster RTLS and center core ASDS landing downrange.

The conclusion is that unless you need something with a capability of > 49mt then a reusable configuration would work just fine. Even woC/F you get about 41mt reusable.
Good work OldAtlas.
If your reusable values are correct then <$2000/kg to LEO should be possible, maybe even <$1500/kg.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/03/2015 09:01 PM
nadreck
You are probably correct in that there may never be a plain FHC/F. If or when they get RTLS working FH is unlikely to ever fly a non -reusable configuration after that even if only the boosters are recovered. A C/F where the center core is expended would cost $25M more or a price as low as $85M. Those values of $90M in the NASA Moon return study for FH usage and costs starts to look like they may be closer to correct than we think. Maybe they got some probable pricing data from SpaceX for the FH2Rv1.2C/F configuration that could do what they specified for TLI.

Why would they expend the center core, ever?  Barge landings, if they're done without boost-back, cost very little propellant and have to be cheaper than $25M...   Or am I reading your logic wrong?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/03/2015 09:11 PM
nadreck
You are probably correct in that there may never be a plain FHC/F. If or when they get RTLS working FH is unlikely to ever fly a non -reusable configuration after that even if only the boosters are recovered. A C/F where the center core is expended would cost $25M more or a price as low as $85M. Those values of $90M in the NASA Moon return study for FH usage and costs starts to look like they may be closer to correct than we think. Maybe they got some probable pricing data from SpaceX for the FH2Rv1.2C/F configuration that could do what they specified for TLI.

Why would they expend the center core, ever?  Barge landings, if they're done without boost-back, cost very little propellant and have to be cheaper than $25M...   Or am I reading your logic wrong?

From my perspective I don't think they will ever find a reason to do C/F at a $25M price tag. Throwing away the centre core without C/F represents at most a $40M cost (more likely $10 to $30M based on it being a used core), and it more than doubles GSO and higher energy payloads, and more than a 50% increase to GTO over a FH3R (downrange recovery of centre core). If C/F costs $25M more per flight than non C/F but you try to use it on a centre core that is recovered down range, you are limited to a centre core flight profile that has enough fuel to boost the centre core back from >6km/s to re-enter and land on a very down range ASDS to have as much performance to GTO, GSO and beyond as a disposable centre core NON C/F flight profile and at best it saves you $15M.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/03/2015 09:25 PM
Interesting calculations. I keep wondering how much FH non cf with disposable central core could send to Mars. That might be something SpaceX wants to do and I would like to know if a Red Dragon can be sent to Mars expending only the central core. Red Dragon might be 10t.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/03/2015 09:32 PM
Interesting calculations. I keep wondering how much FH non cf with disposable central core could send to Mars. That might be something SpaceX wants to do and I would like to know if a Red Dragon can be sent to Mars expending only the central core. Red Dragon might be 10t.

From their website 13,200kg
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/03/2015 09:55 PM
nadreck
You are probably correct in that there may never be a plain FHC/F. If or when they get RTLS working FH is unlikely to ever fly a non -reusable configuration after that even if only the boosters are recovered. A C/F where the center core is expended would cost $25M more or a price as low as $85M. Those values of $90M in the NASA Moon return study for FH usage and costs starts to look like they may be closer to correct than we think. Maybe they got some probable pricing data from SpaceX for the FH2Rv1.2C/F configuration that could do what they specified for TLI.

Why would they expend the center core, ever?  Barge landings, if they're done without boost-back, cost very little propellant and have to be cheaper than $25M...   Or am I reading your logic wrong?

From my perspective I don't think they will ever find a reason to do C/F at a $25M price tag. Throwing away the centre core without C/F represents at most a $40M cost (more likely $10 to $30M based on it being a used core), and it more than doubles GSO and higher energy payloads, and more than a 50% increase to GTO over a FH3R (downrange recovery of centre core). If C/F costs $25M more per flight than non C/F but you try to use it on a centre core that is recovered down range, you are limited to a centre core flight profile that has enough fuel to boost the centre core back from >6km/s to re-enter and land on a very down range ASDS to have as much performance to GTO, GSO and beyond as a disposable centre core NON C/F flight profile and at best it saves you $15M.

I'm not following you - I might have missed some logic upthread.

Where is the $25M coming from?  I assumed it is the write-off cost of the center core if you expend it.

If you recover down-range, you save the $25M, and your costs are the barge ops and the re-entry propellant, which might be a few km/s dV, but on an otherwise empty stage.

They might not have a customer now, but if they'll use FH for refueling MCTs, it'll make sense to get as much performance out of them as possible.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: francesco nicoli on 09/03/2015 10:09 PM
the logic is that if you don't recover the cetral core you get more payload to GEO; in fact 50% more, so 50% payload more to GEO is well worthy 20M.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/03/2015 10:28 PM
the logic is that if you don't recover the cetral core you get more payload to GEO; in fact 50% more, so 50% payload more to GEO is well worthy 20M.

For that to be true, you need to show that recovering the center core downrange costs 33% of the payload.

I thought that was the number when considering RTLS, and even that was deemed acceptable.

You need to look at cost, since that's the ultimate driver.

If the other two cores are reused, an expendable center core becomes the most expensive component in the stack, and so you're highly motivated to reuse it too - it's much more than "one core out of three".  Luckily, they have down-range recovery capabilities, which has a lower payload penalty than RTLS, so I can't see why they'd refrain from using it.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/03/2015 10:55 PM
the logic is that if you don't recover the cetral core you get more payload to GEO; in fact 50% more, so 50% payload more to GEO is well worthy 20M.

For that to be true, you need to show that recovering the center core downrange costs 33% of the payload.

I thought that was the number when considering RTLS, and even that was deemed acceptable.

You need to look at cost, since that's the ultimate driver.

If the other two cores are reused, an expendable center core becomes the most expensive component in the stack, and so you're highly motivated to reuse it too - it's much more than "one core out of three".  Luckily, they have down-range recovery capabilities, which has a lower payload penalty than RTLS, so I can't see why they'd refrain from using it.

No it costs more like 50% of the payload beyond GTO, it costs much less against the LEO payload figures.  If people have time to wait, I will put up a break down of based on the assumptions I was using to calculate from either tomorrow or sometime over the weekend.

nadreck
You are probably correct in that there may never be a plain FHC/F. If or when they get RTLS working FH is unlikely to ever fly a non -reusable configuration after that even if only the boosters are recovered. A C/F where the center core is expended would cost $25M more or a price as low as $85M. Those values of $90M in the NASA Moon return study for FH usage and costs starts to look like they may be closer to correct than we think. Maybe they got some probable pricing data from SpaceX for the FH2Rv1.2C/F configuration that could do what they specified for TLI.

Why would they expend the center core, ever?  Barge landings, if they're done without boost-back, cost very little propellant and have to be cheaper than $25M...   Or am I reading your logic wrong?

From my perspective I don't think they will ever find a reason to do C/F at a $25M price tag. Throwing away the centre core without C/F represents at most a $40M cost (more likely $10 to $30M based on it being a used core), and it more than doubles GSO and higher energy payloads, and more than a 50% increase to GTO over a FH3R (downrange recovery of centre core). If C/F costs $25M more per flight than non C/F but you try to use it on a centre core that is recovered down range, you are limited to a centre core flight profile that has enough fuel to boost the centre core back from >6km/s to re-enter and land on a very down range ASDS to have as much performance to GTO, GSO and beyond as a disposable centre core NON C/F flight profile and at best it saves you $15M.

I'm not following you - I might have missed some logic upthread.

Where is the $25M coming from?  I assumed it is the write-off cost of the center core if you expend it.

If you recover down-range, you save the $25M, and your costs are the barge ops and the re-entry propellant, which might be a few km/s dV, but on an otherwise empty stage.

They might not have a customer now, but if they'll use FH for refueling MCTs, it'll make sense to get as much performance out of them as possible.


I was taking the $25M OldAtlasGuy quoted for making C/F happen on a per flight basis. I consider that a throwaway of a centre core costs at the high end the cost of a centre core new at the high end less the cost of refurbishing and relaunching a used centre core (so about $30-$40M at the top end) but if it was a near end of life core maybe it is only a $10M cost.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/04/2015 01:24 AM
the logic is that if you don't recover the cetral core you get more payload to GEO; in fact 50% more, so 50% payload more to GEO is well worthy 20M.

For that to be true, you need to show that recovering the center core downrange costs 33% of the payload.

I thought that was the number when considering RTLS, and even that was deemed acceptable.

You need to look at cost, since that's the ultimate driver.

If the other two cores are reused, an expendable center core becomes the most expensive component in the stack, and so you're highly motivated to reuse it too - it's much more than "one core out of three".  Luckily, they have down-range recovery capabilities, which has a lower payload penalty than RTLS, so I can't see why they'd refrain from using it.

No it costs more like 50% of the payload beyond GTO, it costs much less against the LEO payload figures.  If people have time to wait, I will put up a break down of based on the assumptions I was using to calculate from either tomorrow or sometime over the weekend.

nadreck
You are probably correct in that there may never be a plain FHC/F. If or when they get RTLS working FH is unlikely to ever fly a non -reusable configuration after that even if only the boosters are recovered. A C/F where the center core is expended would cost $25M more or a price as low as $85M. Those values of $90M in the NASA Moon return study for FH usage and costs starts to look like they may be closer to correct than we think. Maybe they got some probable pricing data from SpaceX for the FH2Rv1.2C/F configuration that could do what they specified for TLI.

Why would they expend the center core, ever?  Barge landings, if they're done without boost-back, cost very little propellant and have to be cheaper than $25M...   Or am I reading your logic wrong?

From my perspective I don't think they will ever find a reason to do C/F at a $25M price tag. Throwing away the centre core without C/F represents at most a $40M cost (more likely $10 to $30M based on it being a used core), and it more than doubles GSO and higher energy payloads, and more than a 50% increase to GTO over a FH3R (downrange recovery of centre core). If C/F costs $25M more per flight than non C/F but you try to use it on a centre core that is recovered down range, you are limited to a centre core flight profile that has enough fuel to boost the centre core back from >6km/s to re-enter and land on a very down range ASDS to have as much performance to GTO, GSO and beyond as a disposable centre core NON C/F flight profile and at best it saves you $15M.

I'm not following you - I might have missed some logic upthread.

Where is the $25M coming from?  I assumed it is the write-off cost of the center core if you expend it.

If you recover down-range, you save the $25M, and your costs are the barge ops and the re-entry propellant, which might be a few km/s dV, but on an otherwise empty stage.

They might not have a customer now, but if they'll use FH for refueling MCTs, it'll make sense to get as much performance out of them as possible.


I was taking the $25M OldAtlasGuy quoted for making C/F happen on a per flight basis. I consider that a throwaway of a centre core costs at the high end the cost of a centre core new at the high end less the cost of refurbishing and relaunching a used centre core (so about $30-$40M at the top end) but if it was a near end of life core maybe it is only a $10M cost.

50% is a tall claim, I'd be happy to see a rocket equation spreadsheet showing that. 

And the $25M to make C/F happen?  that's a lot of money.    After the design work is done, you're talking about a finite set of valves and piping.   No extra pumps, no extra engines, no extra tanks.   The hardware is not expensive. Certainly not $25M - that's like an entirely new stage almost.

SpaceX will have two choices, much as it has with F9H.

A) expend the center core and get a certain amount more performance.
B) perform reentry and recover the stage way downrange with a barge, and eliminate the biggest cost component in the rocket.

If core reusability works, then I can't see it being anything but option B.

The places where it gets interesting is whether to fly C/F and be able to RTLS, or fly simple FH and recover on a barge.  That's a viable trade-off.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/04/2015 06:02 AM
Interesting calculations. I keep wondering how much FH non cf with disposable central core could send to Mars. That might be something SpaceX wants to do and I would like to know if a Red Dragon can be sent to Mars expending only the central core. Red Dragon might be 10t.

From their website 13,200kg

That's the performance of a fully expendable FH. It would be a lot cheaper if TMI for a Red Dragon can be done with reusable side boosters. That was my question, if anybody can calculate the TMI performance with booster RTLS.

Edit: Just watched the latest Red Dragon video again. For a full payload of 2 ton landed on Mars the weight of Red Dragon incl. trunk would be ~11t. Very likely too much for recovering the side boosters. Maybe if the payload is reduced to 1t, the Dragon weight would be slightly below 10t. That weight might be possible with recovery of the side boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: SpaceXfan on 09/04/2015 11:22 AM
It's going to be some production rate, with catching up post RTF and FH coming online!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dorkmo on 09/04/2015 10:00 PM


SpaceX has updated the renderings on their F9/FH pages with the "v1.2" renderings, which are more detailed, and presumably accurate. It does seem to indicate a ~6ft stretch as well in the upper stage.

Here is the old (left) FH rendering compared to the new one (right), but it is difficult to match them exactly:

Changes:
 - stretched upper stage
 - more detail on booster attachment
 - grid fins

And a larger interstage.

Cheers, Martin

It indeed does looks a bit longer.
Also, the leg's seem shorter and the center engine alignment is different. This could be just the rendering ofcourse.

it looks to me like the previous render was displayed in parallel projection, while the new one is displayed in perspective from a long viewing distance. i think thats whats making the center engine look different.

i just thought about this again and perhaps they cut and pasted the engines from one render onto a different render. the stages are too perfectly straight to be perspective. if it was parallel at an angle the horizontal lines between stages would be curved.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/04/2015 11:01 PM
the logic is that if you don't recover the cetral core you get more payload to GEO; in fact 50% more, so 50% payload more to GEO is well worthy 20M.

For that to be true, you need to show that recovering the center core downrange costs 33% of the payload.

I thought that was the number when considering RTLS, and even that was deemed acceptable.

You need to look at cost, since that's the ultimate driver.

If the other two cores are reused, an expendable center core becomes the most expensive component in the stack, and so you're highly motivated to reuse it too - it's much more than "one core out of three".  Luckily, they have down-range recovery capabilities, which has a lower payload penalty than RTLS, so I can't see why they'd refrain from using it.

No it costs more like 50% of the payload beyond GTO, it costs much less against the LEO payload figures.  If people have time to wait, I will put up a break down of based on the assumptions I was using to calculate from either tomorrow or sometime over the weekend.

Ok so I had a chance to work on that and put a spread sheet together (and it also answers Guckyfan's question more or less).

For a detailed explanation of the spreadsheets followed by the steps of how I used them to come up with the following scenarios see bellow, but for the tl;dr crowd who just want the results without any intermediate steps:

So if we presume that we are presuming a 200 KM LEO orbit and that GTO is a 2450m/s impulse past that then here are the following capabilities of an FH either with side boosters RTLS and centre core recovered down range:

25t to LEO with centre core landing down range and side cores RTLS
40t to LEO with centre core expended and side cores landing down range
8t to GTO with centre core landing down range and side cores RTLS
17t to GTO with centre core expended and side cores landing down range

For Guckyfan's question on TMI presuming that TMI is accomplished with an impulse of 1.3km/s more than GTO:

3t to TMI with centre core landing down range and side cores RTLS
9t to TMI with centre core expended and side cores landing down range


So I put together a spreadsheet with four worksheets. The first worksheet {Upper Stage} is where I started and it characterizes the performance of the upper stage with different payloads. I have done this exercise before and I did here (and throughout) use V1.1 specs not Full Thrust specs. The assumptions for dry weight propellant load ISP and thrust are: 5 metric tons, 93 metric tons, 340 seconds and 934kN respectively. There is a table there with the resulting ΔV and maximum acceleration given different payloads from 1t to 20t in 1t increments and to 55t from there in 5t increments.

The next worksheet {Boost Back Recovery performance} calculates a table of required remaining propellant for a recoverable Falcon first stage for various ΔV values mostly in 500m/s increments but with the first one being 400m/s which is what I presume the landing maneuver requires and it is calculated based on sea level Isp. All the remaining steps have the total required propellant calculated based on the difference from 400m/s to that lines speed based on the M1D 100% thrust engine at its vacuum ISP since the retropulsion maneuver is carried out around 25 to 35 km for the side cores and much higher for the centre core. I presume that the retropulsion requirement for a landing down range is to reduce the velocity to roughly 1km/s for re-entry. For RTLS I take a more liberal interpretation since it starts at a higher altitude but presume that RTLS from a core travelling about 1500m/s can be accomplished with a total ΔV of 3500m/s.

The next worksheet {Centre core performance} details the performance of the centre core after the side boosters seperate under a few different assumptions. One set of assumptions was based around landing down range and includes the 2.5t of dry weight for that plus requires about 15% fuel load to retropulse and land from the speed somewhere between 3000 and 3500m/s that I had roughed out before my final table was created as the speed it would achieve. The other set of assumptions presumed it was expendable and did not maintain any reserve of fuel and had a dry weight that did not reflect legs and other recovery oriented hardware.  Each of the two tables presented ΔV calculated for different payload weights AND with different starting propellant loads (ie how much would be left over when the side boosters dropped off) note that this presumed some sort of reduction of centre core engines firing and reducing thrust to 70% on the remaining engines up to side core separation.

The last worksheet {Booster performance} was a second by second model of the flight of the 3 booster phase to calculate remaining propellant, altitude and horizontal velocity and allow for gravity loss. Three of the columns in that table of calculations I varied based on what I thought the rate of turn would approximate to and how many centre core engines were optimal to be firing at each step along the way.

So how I use the worksheets to come up with the numbers I had above:

I decide whether the side boosters are going to be recovered down range, RTLS or thrown away and I look at the {Boost back recovery performance} and see that I probably need somewhere between 15 and 20% of my side booster propellant remaining. 

I go to {Booster performance} and I take what I expect the final payload to be and put it in cell C5 (you can go back and refine this later if you are off by any amount but note that it will only make a few meters per second difference to the performance of the boost stage).

Then I go down the table until the remaining booster propellant roughly matches what I need and check that the velocity I expected isn't much higher or lower than what I expected for the boost back maneuver (look near 153 seconds). I take the horizontal velocity from there and note it and then the % of centre core propellant remaining.

Then go to {Centre core performance} and if I plan on recovering the centre core I use the second table, if not I use the first. From the appropriate table I note the ΔV for the approximate weight I am anticipating (round up) and in the column closest to the percentage of propellant remaining. That added to the velocity that I noted in the first step is how much I have towards my mission requirements so far.

Lastly I work out what remaining velocity I need and look that up on the table on {Upper Stage} and if the weight is wildly off from what I expected I start over with the weight that I got from this exercise as the approximate for the other steps that required a guess at the final payload weight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/04/2015 11:26 PM
i just thought about this again and perhaps they cut and pasted the engines from one render onto a different render. the stages are too perfectly straight to be perspective. if it was parallel at an angle the horizontal lines between stages would be curved.

No look closer on the full size render. lines at the very top (where the fairing meets the upper stage) and bottom are not completely straight. It is a perspective render, but an extreme one that is almost orthogonal.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/05/2015 04:49 AM

So if we presume that we are presuming a 200 KM LEO orbit and that GTO is a 2450m/s impulse past that then here are the following capabilities of an FH either with side boosters RTLS and centre core recovered down range:

25t to LEO with centre core landing down range and side cores RTLS
40t to LEO with centre core expended and side cores landing down range
8t to GTO with centre core landing down range and side cores RTLS
17t to GTO with centre core expended and side cores landing down range


So first, you're double presuming up there, and I don't know if that's legal.

Less importantly, this is not an apples to apples comparison.  You're evaluating the two center core options (expend it or recover downrange) under two different scenarios (side core RTLS and side core down-range recovery)

The question was, suppose we RTLS the side cores, what is the payload hit for recovering the center core deep downrange as opposed to expending it.

You will need to make some assumptions on the amount of slow-down necessary before re-entry, and we don't quite know what that is.

My understanding is that they were able to get by with a rather minimal braking burn on a regular F9 launch, and so I would guestimate that they need to slow down from center-core speed (which we don't quite know either) to just under single-core speed. (which we should have a better guess at)

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/05/2015 05:57 AM

So if we presume that we are presuming a 200 KM LEO orbit and that GTO is a 2450m/s impulse past that then here are the following capabilities of an FH either with side boosters RTLS and centre core recovered down range:

25t to LEO with centre core landing down range and side cores RTLS
40t to LEO with centre core expended and side cores landing down range
8t to GTO with centre core landing down range and side cores RTLS
17t to GTO with centre core expended and side cores landing down range


So first, you're double presuming up there, and I don't know if that's legal.

Less importantly, this is not an apples to apples comparison.  You're evaluating the two center core options (expend it or recover downrange) under two different scenarios (side core RTLS and side core down-range recovery)

The question was, suppose we RTLS the side cores, what is the payload hit for recovering the center core deep downrange as opposed to expending it.

You will need to make some assumptions on the amount of slow-down necessary before re-entry, and we don't quite know what that is.

My understanding is that they were able to get by with a rather minimal braking burn on a regular F9 launch, and so I would guestimate that they need to slow down from center-core speed (which we don't quite know either) to just under single-core speed. (which we should have a better guess at)

I assumed slowing down to 900m/s and using 400m/s of delta V to land that is all in my spread sheets, if you don't read my spreadsheets and assumptions then you are simply left with taking my conclusions with out any reasoning behind it and can't criticize it.

My first worksheet details the performance of the Falcon upper stage that is not vague or wishy washy, the data in there is quite reliable and that is how you find out what the speed the centre core has to reach to reach for a given payload to get to a given mission.

The rest of the assumptions are based on what we know about the V1.1 centre core. We do know they need to slow down, 900m/s was the number that seemed indicated by the flights where they attempted boost back or down range landing.

RTLS but expending the centre core obviously results in a value between RTLS and center core recovery down range and sidebooster recovery down range and centre core expended, my spreadsheet can easily give you that if you follow the steps to use it. I just don't know what the point is RTLS isn't of particular high value over downrange recovery and we know 3 stages can't RTLS, as well we assume from current data that there will be 2 ASDS's not 3.  So it makes sense to consider RTLS side boosters/centre core recovery as the 3R option and side booster ASDS recovery and centre core expended as the alternative higher payload.  The savings of RTLS over ASDS on the side boosters is  minimal in comparison to the cost of expending the core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/05/2015 06:05 AM
For Guckyfan's question on TMI presuming that TMI is accomplished with an impulse of 1.3km/s more than GTO:

3t to TMI with centre core landing down range and side cores RTLS
9t to TMI with centre core expended and side cores landing down range

Thanks a lot. Sadly this seems to indicate that Red Dragon needs a fully expended FH which is still quite reasonable for a NASA mission but expensive for a mission self funded by SpaceX.

Note: side cores downrange, is that even an option? It would need two ASDS or possibly a new landing site in Florida assuming launch from Texas.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/05/2015 06:22 AM
For Guckyfan's question on TMI presuming that TMI is accomplished with an impulse of 1.3km/s more than GTO:

3t to TMI with centre core landing down range and side cores RTLS
9t to TMI with centre core expended and side cores landing down range

Thanks a lot. Sadly this seems to indicate that Red Dragon needs a fully expended FH which is still quite reasonable for a NASA mission but expensive for a mission self funded by SpaceX.

Note: side cores downrange, is that even an option? It would need two ASDS or possibly a new landing site in Florida assuming launch from Texas.

Side cores won't have gone all that far, and given that there seem to be more than 2 ASDS's in the Atlanatic (at least as far as I recall from the very long winded ASDS thread) I think they could be recovered handily. Also expending the side cores would add between 400 and 500m/s which doesn't sound like much but would push the TMI number up past 11, however Full Thrust and densification might do as much, put the two together maybe you get 13. Remember I used vanilla V1.1 stats to build these tables yet after Jason-3 there will be no more vanilla V1.1.



Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/05/2015 06:40 AM
That ASDS thread was really long winded. :)

For a short time it was thought there would be 3 ASDS. But we know now that Marmac 300 was decomissioned as an ASDS so there are two, one Atlantic, one Pacific. They would have to build a new one for sidebooster recovery.

I missed, that the numbers were 1.1. So payload to Mars with booster recovery is still possible. According to the Red Dragon video it would require ~11t to TMI for a full 2t payload to the surface. Which is not a bad payload fraction. It is similar to the payload fraction of Curiosity.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Mangala on 09/05/2015 12:52 PM
For Guckyfan's question on TMI presuming that TMI is accomplished with an impulse of 1.3km/s more than GTO:

3t to TMI with centre core landing down range and side cores RTLS
9t to TMI with centre core expended and side cores landing down range

Thanks a lot. Sadly this seems to indicate that Red Dragon needs a fully expended FH which is still quite reasonable for a NASA mission but expensive for a mission self funded by SpaceX.

Note: side cores downrange, is that even an option? It would need two ASDS or possibly a new landing site in Florida assuming launch from Texas.

Side cores won't have gone all that far, and given that there seem to be more than 2 ASDS's in the Atlanatic (at least as far as I recall from the very long winded ASDS thread) I think they could be recovered handily. Also expending the side cores would add between 400 and 500m/s which doesn't sound like much but would push the TMI number up past 11, however Full Thrust and densification might do as much, put the two together maybe you get 13. Remember I used vanilla V1.1 stats to build these tables yet after Jason-3 there will be no more vanilla V1.1.
Have you made some calculations for a payload to the moon? I'm asking this because I was thinking about something I read  a wile ago about the possibility of SpaceX launching a Dragon capsule (like CRS-5 one) for a free ride around the moon and then to retrieve it in the Pacific Ocean on the inaugural launch of the Falcon Heavy next spring.
Moderation: Feel free to change this comment for a most appropriate thread.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/05/2015 04:32 PM


The question was, suppose we RTLS the side cores, what is the payload hit for recovering the center core deep downrange as opposed to expending it.

Using my original tables I get 15t expending the centre core and RTLSing the side cores so a 2t hit over sending the side cores out to sea for recovery. So we go from side core RTLS + centre stage ASDS at 8t to side core RTLS + centre stage disposal at 15t.

Note I am updating the spread sheet to work with cross feed scenarios as well, will post later today or tonight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/05/2015 04:57 PM

So if we presume that we are presuming a 200 KM LEO orbit and that GTO is a 2450m/s impulse past that then here are the following capabilities of an FH either with side boosters RTLS and centre core recovered down range:

25t to LEO with centre core landing down range and side cores RTLS
40t to LEO with centre core expended and side cores landing down range
8t to GTO with centre core landing down range and side cores RTLS
17t to GTO with centre core expended and side cores landing down range


So first, you're double presuming up there, and I don't know if that's legal.

Less importantly, this is not an apples to apples comparison.  You're evaluating the two center core options (expend it or recover downrange) under two different scenarios (side core RTLS and side core down-range recovery)

The question was, suppose we RTLS the side cores, what is the payload hit for recovering the center core deep downrange as opposed to expending it.

You will need to make some assumptions on the amount of slow-down necessary before re-entry, and we don't quite know what that is.

My understanding is that they were able to get by with a rather minimal braking burn on a regular F9 launch, and so I would guestimate that they need to slow down from center-core speed (which we don't quite know either) to just under single-core speed. (which we should have a better guess at)

I assumed slowing down to 900m/s and using 400m/s of delta V to land that is all in my spread sheets, if you don't read my spreadsheets and assumptions then you are simply left with taking my conclusions with out any reasoning behind it and can't criticize it.


Yeah, I saw later, it takes a second to get into someone else's spreadsheet.  We can talk about these numbers later, but I was criticizing the comparison, not the spreadsheet.

You're supposed to compare expend/recover of center core under identical assumptions.

Instead, you compared:
- recover-center-core with side-core-RTLS, to
- expend-center-core with side-core-downrange

Which inflates the difference in payload to orbit (any orbit) - the "expend" version benefits from not having to RTLS the side cores.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/05/2015 05:31 PM

You're supposed to compare expend/recover of center core under identical assumptions.

Instead, you compared:
- recover-center-core with side-core-RTLS, to
- expend-center-core with side-core-downrange

Which inflates the difference in payload to orbit (any orbit) - the "expend" version benefits from not having to RTLS the side cores.

I didn't have any reason to make the comparison that you were suggesting, to me it was what was the maximum payload with 3 cores recovered (which implied RTLS on the sides from discussions here saying we would never see 3 cores recovered by ASDS but might see two) against what was the maximum with 2 cores recovered and maximum for that presumes the cores go down range not RTLS.

However notice that the big hit, as I stated all along is recovering the centre core because of the massive penalty that boost back makes when the centre core is moving faster than 4km/s when it separates from the upper stage.   For the TMI number on the SpaceX web site (13,200 kg) it implies (with a V1.1 legacy upper stage) that the 2nd stage was moving at least 5.6km/s at 2nd stage ignition
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/06/2015 03:38 AM
So here is the updated spreadsheet.

I added a 2nd column on the tables in the {Centre core performance} worksheet for 100% remaining propellant for the cross feed case, and I added another table allowing for 20% propellant reserve for recovering the centre core in that case. I also added another worksheet for the 3 booster boost phase in the cross feed scenario.

So with the cross feed and side boosters RTLS'ing and centre core recovery down range

The payload to GTO would be 12t

with cross feed and side boosters RTLS'ing and centre core expending the payload to GTO is 20t

GTO performance with side cores recovered down range and centre core expended is 25t


TMI under those same 3 cases is, respectively, 5t, 12t and 14t


REMEMBER this is V1.1 legacy specs not the new full thrust.

ALSO note that my spreadsheet does not calculated several factors, that while some cancel others, it is still only an approximation and a better indication of relative performance rather than absolute. On the underestimating side it presumes sea level ISP for the 3 core boost phase, also when coming up with my delta V budgets for the scenarios I ignored the benefit of launching east from the cape. On the other side of the ledger I didn't allow for air resistance  and while I accounted for gravity loss in the 3 core boost phase I ignored it after that and while it is minimal after that it is not zero.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: meekGee on 09/06/2015 05:07 AM
So here is the updated spreadsheet.

I added a 2nd column on the tables in the {Centre core performance} worksheet for 100% remaining propellant for the cross feed case, and I added another table allowing for 20% propellant reserve for recovering the centre core in that case. I also added another worksheet for the 3 booster boost phase in the cross feed scenario.

So with the cross feed and side boosters RTLS'ing and centre core recovery down range

The payload to GTO would be 12t

with cross feed and side boosters RTLS'ing and centre core expending the payload to GTO is 20t

GTO performance with side cores recovered down range and centre core expended is 25t


TMI under those same 3 cases is, respectively, 5t, 12t and 14t


REMEMBER this is V1.1 legacy specs not the new full thrust.

ALSO note that my spreadsheet does not calculated several factors, that while some cancel others, it is still only an approximation and a better indication of relative performance rather than absolute. On the underestimating side it presumes sea level ISP for the 3 core boost phase, also when coming up with my delta V budgets for the scenarios I ignored the benefit of launching east from the cape. On the other side of the ledger I didn't allow for air resistance  and while I accounted for gravity loss in the 3 core boost phase I ignored it after that and while it is minimal after that it is not zero.

K, thanks.  Hope to have time to dive into this tomorrow.  That's what the holiday is for, innit?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: JoerTex on 09/09/2015 03:08 PM
Aviation Week has a new item on Falcon Heavy.  Lists launch customers.  First launch is SpaceX funded test.

http://aviationweek.com/space/spacex-introduce-falcon-heavy-early-2016-0?NL=AW-19&Issue=AW-19_20150909_AW-19_329&sfvc4enews=42&cl=article_4&utm_rid=CPEN1000000903672&utm_campaign=3734&utm_medium=email&elq2=0bc134d29fc64b68921dade1f49f5f80
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: symbios on 09/09/2015 03:44 PM
Aviation Week has a new item on Falcon Heavy.  Lists launch customers.  First launch is SpaceX funded test.

http://aviationweek.com/space/spacex-introduce-falcon-heavy-early-2016-0?NL=AW-19&Issue=AW-19_20150909_AW-19_329&sfvc4enews=42&cl=article_4&utm_rid=CPEN1000000903672&utm_campaign=3734&utm_medium=email&elq2=0bc134d29fc64b68921dade1f49f5f80

Behind a paywall  :-\
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Roy_H on 09/09/2015 05:10 PM
Aviation Week has a new item on Falcon Heavy.  Lists launch customers.  First launch is SpaceX funded test.

http://aviationweek.com/space/spacex-introduce-falcon-heavy-early-2016-0?NL=AW-19&Issue=AW-19_20150909_AW-19_329&sfvc4enews=42&cl=article_4&utm_rid=CPEN1000000903672&utm_campaign=3734&utm_medium=email&elq2=0bc134d29fc64b68921dade1f49f5f80

Haven't read the full article, but I'm willing to bet all the info is on this web site, and probably came from here. Anybody know if there is actually anything new?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wxmeddler on 09/09/2015 05:35 PM
I suppose this is the news?
Quote
Peter B. de Selding @pbdes
ViaSat: Our ViaSat-2 sat to launch on Falcon Heavy in Q4 2016, after 1st Falcon Heavy ~ May. Plan B, an Ariane 5, would cost time & money.
https://twitter.com/pbdes/status/641654264918634496
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Burninate on 09/09/2015 05:44 PM
That ASDS thread was really long winded. :)

For a short time it was thought there would be 3 ASDS. But we know now that Marmac 300 was decomissioned as an ASDS so there are two, one Atlantic, one Pacific. They would have to build a new one for sidebooster recovery.

I missed, that the numbers were 1.1. So payload to Mars with booster recovery is still possible. According to the Red Dragon video it would require ~11t to TMI for a full 2t payload to the surface. Which is not a bad payload fraction. It is similar to the payload fraction of Curiosity.

For Guckyfan's question on TMI presuming that TMI is accomplished with an impulse of 1.3km/s more than GTO:

3t to TMI with centre core landing down range and side cores RTLS
9t to TMI with centre core expended and side cores landing down range

Thanks a lot. Sadly this seems to indicate that Red Dragon needs a fully expended FH which is still quite reasonable for a NASA mission but expensive for a mission self funded by SpaceX.

Note: side cores downrange, is that even an option? It would need two ASDS or possibly a new landing site in Florida assuming launch from Texas.

Side cores won't have gone all that far, and given that there seem to be more than 2 ASDS's in the Atlanatic (at least as far as I recall from the very long winded ASDS thread) I think they could be recovered handily. Also expending the side cores would add between 400 and 500m/s which doesn't sound like much but would push the TMI number up past 11, however Full Thrust and densification might do as much, put the two together maybe you get 13. Remember I used vanilla V1.1 stats to build these tables yet after Jason-3 there will be no more vanilla V1.1.

Side cores are designed in such a way that it's easy for them to land back at or near the launch site, there's only minimal boostback in achieving that.  However, it may still be advantageous to land them on barges, not because it would be a large performance benefit (nonzero, but not large), but because of landing site liability & PR.  If the fully-risked-out cost of landing at a pad is more than the cost of another ASDS, they'll go with the ASDS.  The center core will likely always land at an ASDS - it's a technically prohibitive payload penalty for them to boost that back to the launchsite.

On Falcon 9, boostback is much more intense than a side core, but may be technically achievable for smaller payloads; it's unclear whether they'll ever land without an ASDS.

It's looking like they're trying to secure the two pads on the Cape for landing;  I don't think we'll know whether it's passed all the people who can veto that landing until they actually do it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: BrianNH on 09/09/2015 05:59 PM
Article says 4 launches of FH in 2016: Demo (April or May), STP-2 in Sept., ViaSat and InmarSat.

Also says that they plan to manufacture equal numbers of F9 and FH.

Lots of other info, but just repeating what was already said at recent conferences, which we already know.

Still expect Pad 39A to be operational in November.  LOTS of changes for the F9 upgrade - some may have been for FH, wording was a bit unclear.  Updated grid fins, landing legs, "core stage structure". 

An interesting one that I had not heard before is a change in the octaweb configuration.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 09/16/2015 03:15 PM
I saw an interesting discussion elsewhere on the internet and I'd like to ask you guys a few things.

I'll start off with this premise: In the future, SpaceX is replacing the Falcon Heavy. What do you think is most likely, and why?

1. Falcon Heavy with improved Merlins, even methalox Merlins of some design
2. Falcon Heavy with Raptor engines
3. Single core stick in between whatever Falcon 9 they are using at the time and the BFR in size

Which is the most economical to use? Which is the easiest to build? Which is the best performer?

(This image is not real or official).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: RonM on 09/16/2015 03:34 PM
1. SpaceX will probably continue to improve the Merlin engine. Switching fuel to standardize the fleet has benefits, but it might be too difficult or expensive to make a methane Merlin.
2. Three Raptor engines on a F9 core might not be able to throttle down enough for landing the core.
3. We don't know enough about the BFR. Seems to me a third class of rocket between F9 and BFR would not be cost effective.

My guess is SpaceX will continue to incrementally improve the F9, but stick with kerosene Merlin engines.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: docmordrid on 09/16/2015 03:53 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 09/16/2015 04:11 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

Where does that leave the loads of progressively smaller satellites they would need to launch to make money?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/16/2015 04:53 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

Where does that leave the loads of progressively smaller satellites they would need to launch to make money?

You launch in bulk. To use an Earth based delivery metaphor: Does it make more sense to ship a lot of small packages in a single truck, or using individual deliveries with motorcycles?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 09/16/2015 04:59 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

Where does that leave the loads of progressively smaller satellites they would need to launch to make money?

You launch in bulk. To use an Earth based delivery metaphor: Does it make more sense to ship a lot of small packages in a single truck, or using individual deliveries with motorcycles?

I suppose this begs the question, what about scheduling conflicts? However, we can probably assume that there will be more satellites needing to be launched each year and that won't be a problem.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: cro-magnon gramps on 09/16/2015 05:05 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

I used to think the same, an intermediate sized LV between the FHR and the BFR. The only problem from my perspective, is the delays and costs involved. How Quickly does SpaceX want to get moving on it's Mars Project? Some early launches of an upgraded FH around 2018-20 is possible for cargo and exploration satellites and practice at launching to Mars; but then there is the cash flow to follow on with the BFR lite or BFR full. How soon can Musk get his Internet Constellation paying for itself? What are the trade offs and the benefits in the short term launch goals for 2020-25? Seems to me we are missing a few pieces of the puzzle.

Would anyone suggest a Raptor powered FHR Shell and replace Dracos/Super Dracos on the Dragon with suitably sized mini-raptors. Simply as a proof of concept test vehicle. Seems crazy just thinking about it.  The real question is, how crazy are Musk and the engineers at SpaceX.  What are they working on behind those curtains?

YES I know (Jim) that LV/SC are not Lego Blocks. So don't disrupt the electrons with a retort ;-)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: bstrong on 09/16/2015 10:27 PM
Where does that leave the loads of progressively smaller satellites they would need to launch to make money?

One way to look at their constellation plans is that SpaceX foresees a model where instead of primarily launching payloads for other customers, they sell a combination of bandwidth and slots for hosted payloads on their own satellites (kind of like datacenter colocation facilities that provide bandwidth, power, cooling, and rack space to their customers).

This puts them in control of launch timing (making ride-sharing easier) and leads to either an increase in satellite size over time as the number of hosted payloads increases or an increase in the number of satellites. Either way, you need bigger rockets.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kansan52 on 09/16/2015 10:54 PM
Feel stupid asking this on an image about guessing about future rockets, but has SX stated plans for a Super Falcon (quad core) and calling all BFRs Eagles?

A quad core will mean new or massively changed assembly buildings, strong backs, and launch sites.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 09/16/2015 11:52 PM
Feel stupid asking this on an image about guessing about future rockets, but has SX stated plans for a Super Falcon (quad core) and calling all BFRs Eagles?

A quad core will mean new or massively changed assembly buildings, strong backs, and launch sites.

No, that image I posted is total fiction. Quad core has diminishing returns and would require a lot of new infrastructure.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Kansan52 on 09/16/2015 11:54 PM
Thanks!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: docmordrid on 09/17/2015 12:18 AM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

I used to think the same, an intermediate sized LV between the FHR and the BFR. The only problem from my perspective, is the delays and costs involved. How Quickly does SpaceX want to get moving on it's Mars Project? Some early launches of an upgraded FH around 2018-20 is possible for cargo and exploration satellites and practice at launching to Mars; but then there is the cash flow to follow on with the BFR lite or BFR full. How soon can Musk get his Internet Constellation paying for itself? What are the trade offs and the benefits in the short term launch goals for 2020-25? Seems to me we are missing a few pieces of the puzzle.

Would anyone suggest a Raptor powered FHR Shell and replace Dracos/Super Dracos on the Dragon with suitably sized mini-raptors. Simply as a proof of concept test vehicle. Seems crazy just thinking about it.  The real question is, how crazy are Musk and the engineers at SpaceX.  What are they working on behind those curtains?

YES I know (Jim) that LV/SC are not Lego Blocks. So don't disrupt the electrons with a retort ;-)

I see it as reducing complexity: fewer lower end vehicle core types (2 with the existing F9 FT & FH cores), 2 vehicles to certify & maintain (mini & full BFR) vs 3, only methane vs methane and RP-1, etc.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: mvpel on 09/17/2015 01:50 AM
No, that image I posted is total fiction.
Probably shouldn't put the SpaceX logo on it, then, lest some hapless journalist mistakes it for a SpaceX publication.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: ZachS09 on 09/17/2015 02:18 AM
I saw an interesting discussion elsewhere on the internet and I'd like to ask you guys a few things.

I'll start off with this premise: In the future, SpaceX is replacing the Falcon Heavy. What do you think is most likely, and why?

1. Falcon Heavy with improved Merlins, even methalox Merlins of some design
2. Falcon Heavy with Raptor engines
3. Single core stick in between whatever Falcon 9 they are using at the time and the BFR in size

Which is the most economical to use? Which is the easiest to build? Which is the best performer?

Was it SpaceX's idea to call their biggest rocket "Eagle"?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 09/17/2015 02:52 AM
No, that image I posted is total fiction.
Probably shouldn't put the SpaceX logo on it, then, lest some hapless journalist mistakes it for a SpaceX publication.

It's already on google images, where I found it. It's by no means mine. It's a year old or so even.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 09/20/2015 02:23 AM
You launch in bulk. To use an Earth based delivery metaphor: Does it make more sense to ship a lot of small packages in a single truck, or using individual deliveries with motorcycles?

Well, Bezos wants to deliver via small flying drones.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/20/2015 06:49 PM
You launch in bulk. To use an Earth based delivery metaphor: Does it make more sense to ship a lot of small packages in a single truck, or using individual deliveries with motorcycles?

Well, Bezos wants to deliver via small flying drones.

The final distance, yes, but not straight from the factory.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: hkultala on 09/20/2015 08:21 PM

Would anyone suggest a Raptor powered FHR Shell and replace Dracos/Super Dracos on the Dragon with suitably sized mini-raptors. Simply as a proof of concept test vehicle. Seems crazy just thinking about it.  The real question is, how crazy are Musk and the engineers at SpaceX.  What are they working on behind those curtains?

YES I know (Jim) that LV/SC are not Lego Blocks. So don't disrupt the electrons with a retort ;-)

No, methane-fueled engine with turbopump won't work as a thruster engine.

Thruster need to have very fast thrust response and ability to start instantly, _very many_ times.

Very fast thrust response mean pressure-fed, no turbopump.

An you need a special ignition system with some another type of fuel to start the methane engine. You cannot restart that hundreds of times without huge amount of the starting fuel. And then you don't need the methane anymore/does not make sense to have the complexity to also to be able to burn also methane.
Title: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/20/2015 10:12 PM
An you need a special ignition system with some another type of fuel to start the methane engine. You cannot restart that hundreds of times without huge amount of the starting fuel. And then you don't need the methane anymore/does not make sense to have the complexity to also to be able to burn also methane.

While tricky, I think you are VASTLY overstating the combustion problem. It is in fact possible to ignite hydrocarbon fuels hundreds, thousands, or more times without special ignition fuel. Doesn't your car do it every time you start it?

Reliable microgravity start is of course very difficult, but not an unsolvable problem.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 09/21/2015 12:54 AM
Methane is natural gas.  50% of homes in America have it for heating, cooking, water heating, and cloths drying.  It is lit and relit 100's if not thousands of time to preform these functions.  Just because it is under pressure going into a combustion chamber doesn't mean it cant be lit or relit.  It doesn't clog up fuel lines and such like kerosene might over time.  It doesn't coke, or very, very little.  It is abundant, and is liquefied all over the country for storage during the summer to be released in winter when it is used most.  It is stored in what looks like giant ground level water tanks or oil tanks.  They are built like a vacuum bottle with walls about 3' or 1m apart.  The space in between is vacuumed out to keep from having heat cause boil off.  The giant tanks are about 200-300' in diameter. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/21/2015 03:37 AM
The Morpheus Moon Lander does have a methane/LOX RCS.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dante80 on 09/21/2015 10:42 AM
Methane is natural gas.  50% of homes in America have it for heating, cooking, water heating, and cloths drying.  It is lit and relit 100's if not thousands of time to preform these functions.  Just because it is under pressure going into a combustion chamber doesn't mean it cant be lit or relit.  It doesn't clog up fuel lines and such like kerosene might over time.  It doesn't coke, or very, very little.  It is abundant, and is liquefied all over the country for storage during the summer to be released in winter when it is used most.  It is stored in what looks like giant ground level water tanks or oil tanks.  They are built like a vacuum bottle with walls about 3' or 1m apart.  The space in between is vacuumed out to keep from having heat cause boil off.  The giant tanks are about 200-300' in diameter.

A question. Will SpaceX use straight LNG for propellant, or will they first enrich it to 100% CH4? Also, any idea on what BO will do for the same application? I remember a hearing where the BO representative firmly said that the BE-4 is not a methane but an LNG engine.

I know that LNG is mostly (up to 98%) methane.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/21/2015 11:05 AM
At one time, quite early, Elon Musk said "mostly methane" and that caused some discussion about possible add ons but most likely he was referring to LNG that way. Selected for high methane content most likely.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 09/21/2015 11:54 AM
1% is odor put in to identify leaks because pure methane is odorless, another 1 or 2 percent is various other flammable gasses like butane and ethane.  It would be very hard and expensive to get it pure, with centrifuges.  Probably not worth the effort.  Making it liquid will probably filter out a lot of the butane and ethane.

Even K1 is probably not 100% K1, it is a refined fuel.  At some point cost to make fuel completely pure outweigh 98%
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 09/21/2015 05:22 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

I tend to disagree.  At least not any time soon.

SpaceX has 4 Falcon pads in operation or in the works.  And only one of those -could- launch anything larger than FH.  That's quite a substantial investment of infrastructure for an LV you are already planning to replace.

So I think the plan is for Falcon to be around for quite some time.

And at the end of the day, even if you have an affordable reusable HLV you -could- launch commercial sats with, you are still launching an F9 or A5-401 class payload (or smaller) with an LV larger than a Saturn V.  That just seems...implausible to me.

Personally, I think it will break down like this 15 years from now.

Falcon is still the workhorse launcher for unmanned sats.
Everything that can launch on F9R will. 
Payloads that would need an F9E will be moved up to FH with 3 reusable RTLS boosters.
Payloads that need more than that will expend the core, or recover it down range on the barge, and the outboard boosters will RTLS.
Playing that would require all 3 FH cores expended will be moved up to BFR-R. 
BFR will have a pretty fully manifest already, and won't have a lot of openings for unmanned sats.  But the occasional large birds that would otherwise need a D4H or FH-E will be fit in.
If BFR is working with a reusable upper stage and/or spacecraft that can carry humans or is working towards that, I think NASA will partner with SpaceX in a big way, and we'll see lunar and Mars missions in the works.  Maybe some NEO missions.  That plus their own designs will keep a single BFR launch complex pretty busy. 

The four Falcon pads will keep launching Falcons for commercial and government comsats.  (3 pads if LC-39A is converted to BFR/MCT).
There could be some further upgrades to Falcon, but the infrastructure for it will be in place and won't be for BFR, which will be much more limited on -where- it can launch do to it's power, and physical size of transportation.  Where Falcon can go by road.

Could the Falcon booster be converted to methane? possibly.  RP-1's pretty cheap too though.  There might be a case for it for purposes of easier reuse (no coking), but it's certainly no imperative I don't think.  A higher ISP upper stage would probably yield the largest improvement in performance...but then commonality is lost with the booster. 

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lobo on 09/21/2015 05:24 PM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

Where does that leave the loads of progressively smaller satellites they would need to launch to make money?

You launch in bulk. To use an Earth based delivery metaphor: Does it make more sense to ship a lot of small packages in a single truck, or using individual deliveries with motorcycles?

Depends if they are all going to the same place or not.

Ariane 5 is being replaced by Ariane 6 because dual payloads going to the same orbit is becoming difficult, as I understand.  So they are downsizing from the truck to the motorcycle.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/21/2015 05:41 PM
1% is odor put in to identify leaks because pure methane is odorless, another 1 or 2 percent is various other flammable gasses like butane and ethane.  It would be very hard and expensive to get it pure, with centrifuges.  Probably not worth the effort.  Making it liquid will probably filter out a lot of the butane and ethane.

Even K1 is probably not 100% K1, it is a refined fuel.  At some point cost to make fuel completely pure outweigh 98%

The odorant concentration is far less than 1% on the order of 1 to 10 parts per million in the natural gas (some are detectable at .1 parts per billion by the human nose). Rules are that natural gas and propane has to be able to be detected by the nose to 1 part per thousand.

Ethane, propane and butane might all be present in natural gas as pipelined to commercial and residential customers the only rules are to keep the specific heat per volume down below a specific level.  Gas plant operators separate out most of the butane, but depending on the relative pricing of propane and ethane they may leave several percent of each in. Ethane rarely has enough value to expend a lot of effort separating it out but some natural gas plans do separate out over 90% of what is there naturally. However, typically about half the propane in the gas from the well head and over 90% of the butane is separated out by cooling the gas stream down. Plants do exist that can cool the gas stream down to get all but a small percentage of the ethane and propane out. However nitrogen(as much as 15%), carbon dioxide(>1%), argon(>1%), neon(between .1 and 1%) and helium(.05 to .8%) are all likely to be present at the well head and nitrogen particularly is an issue to remove however you can't put natural gas in a natural gas pipeline without bringing it down to 4% or so nitrogen. Cryogenic separation is possible but there are cheaper solutions:  - note that just like we have specs for jet grade and rocket grade distillates (kerosene) the same will probably be true for methane for rockets and while it will put the cost up somewhat it will be less than doubling it. (http://www.mtrinc.com/nitrogen_removal.html[/url)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 09/21/2015 06:49 PM
I was an engineer with a natural gas utility for 39 years.  We maintained a .9-1.2% odor concentration, not parts per million.  Sorry 1% is required by the Department of Transportation, Office of Pipeline Safety rules in parts 192 and parts 193 that we maintain .9-1/2% odorant in distribution natural gas.

It is just not economically feasible to get everything out.  We maintained 1000 btu's per 1 cubic foot as much as possible at 6" water column pressure.  Some was less, some more, but not by much.  Adjustments were made in billing to compensate.  Most fracked natural gas, natural gas in wells without oil and in coal seams is not so hard to separate.  When it all boils down, most natural gas nationwide is about 96-97% pure methane. 

Another thing, methane is liquid -161 C, while nitrogen is -196 C, so when making liquid methane from natural gas, the nitrogen will be released that was in the natural gas.  I think people are splitting hairs trying to get from 97 or 98 percent methane any further.  They will liquefy the gas straight from the nearest pipeline at the Launchpad.  It will not be trucked in, or a liquification tanker ship if the BFR Launchpad is at or near a seacoast. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 09/21/2015 07:08 PM
I was an engineer with a natural gas utility for 39 years.  We maintained a .9-1.2% odor concentration, not parts per million.  Sorry 1% is required by the Department of Transportation, Office of Pipeline Safety rules in parts 192 and parts 193 that we maintain .9-1/2% odorant in distribution natural gas.

It is just not economically feasible to get everything out.  We maintained 1000 btu's per 1 cubic foot as much as possible at 6" water column pressure.  Some was less, some more, but not by much.  Adjustments were made in billing to compensate.  Most fracked natural gas, natural gas in wells without oil and in coal seams is not so hard to separate.  When it all boils down, most natural gas nationwide is about 96-97% pure methane. 

Another thing, methane is liquid -161 C, while nitrogen is -196 C, so when making liquid methane from natural gas, the nitrogen will be released that was in the natural gas.  I think people are splitting hairs trying to get from 97 or 98 percent methane any further.  They will liquefy the gas straight from the nearest pipeline at the Launchpad.  It will not be trucked in, or a liquification tanker ship if the BFR Launchpad is at or near a seacoast.

that 1% odor concentration refers to the fact that a 1% concentration of gas has to have a noticeable odor, NOT that the odorant concetration has to be 1%, the regulations now state that a 0.1% concentration of gas has to have a noticeable odor.

see http://aai.solutions/documents/AA_AN011_Measuring-Odorants-in-Natural-Gas-Pipelines.pdf (http://aai.solutions/documents/AA_AN011_Measuring-Odorants-in-Natural-Gas-Pipelines.pdf)  1 - 10 parts per million
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Stan-1967 on 09/21/2015 07:38 PM
It would be opportunistic of SpaceX and all others interested in CH4 for ISRU considerations, to source part of the methane from providers who can demonstrate technical and economic competence at using the Sabatier reaction to produce pure methane.   

The utility of a methane rocket technology will be enhanced for SpaceX & BO/ULA if they can use the opportunity to spur innovation in producing the fuel here on earth.   The effort can be structured to focus on technology paths that can be replicated with raw material not from earth.  The point would be to build supply chain expertise that can at some later day, leave earth and operate at other destinations in the solar system.

It may not be desirable at first to source all methane from these small providers but it would provide a business case for startups if SpaceX or BO/ULA would commit to some mix of sabatier produced methane.   As the tech gets better and cheaper, they can increase the mix without affecting launch price too much.  Fuel is supposedly a small part of overall price anyways.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 09/21/2015 08:04 PM
The odorant we injected may have been diluted since it came in liquid form as it was/is an oil based product.  So it may have read 1% since we injected 1% liquid into the pipeline. 

I still think all are grasping at straws, since natural gas is so cheap and abundant right now with about a 200 year supply, it can be used as is in a rocket.  So it doesn't get a full 100% power but only 98%.  Is that going to kill the rocket engine.  On earth, making natural gas out of water and air could be very expensive in comparison.  That can be left for Mars equipment.  Like I said 98% natural gas, and K1 kerosene might not be 100% either.  There might be some other hydrocarbons in it as well as a trace of water, nothing is 100% pure on earth. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Okie_Steve on 09/21/2015 08:21 PM
The very process of making cryogenic liquid tends to purify them because of fractional liquification and freezing.

We used to buy argon for shielding costly DNA synthesis reactions which were *extremely* sensitive to water degradation. The driest (and most expensive) bottled argon was an order of magnitude "wetter" then run-of-the-mill econo-liquid-argon. When we switched cost went down and yields went up dramatically.

So, the contents of the pipeline are not nearly as important as what comes out at the far end of the liquification process. Water, CO2 and a plethora of other hydrocarbons will be essentially non-existent in the output. CO and N2 migiht be more problematic.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: wannamoonbase on 09/22/2015 04:28 AM
It would be opportunistic of SpaceX and all others interested in CH4 for ISRU considerations, to source part of the methane from providers who can demonstrate technical and economic competence at using the Sabatier reaction to produce pure methane.   

It would be a very Elon thing to do to build a CH4 synthesizing plant near the launch pad, powered by Solar City PV and Tesla power packs. 

The Sabatier reactors and associated processing and storage equipment need to be developed and tested for Mars  Why not next to a test stand and launch pad. 

Electrolisize water, liquefy and store the O2, which is needed anyway.  Use the H2 and find a source of CO2.

It would be a fun exercise to go through the process and energy flow diagrams for such a design. 

I realize it would probably be cheaper to just buy O2 and liquify existing natural gas.  But where is the fun and coolness in that?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: sdsds on 09/22/2015 05:59 AM
I realize it would probably be cheaper to just buy O2 and liquify existing natural gas.  But where is the fun and coolness in that?

If on the day SpX closed the deal on LC-39A (14 April 2014) they had installed a half million dollar photovoltaic Sabatier reactor, and ran it non stop at full speed, would they have enough propellant for a BFR launch in 2020?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: hkultala on 09/22/2015 07:48 AM
An you need a special ignition system with some another type of fuel to start the methane engine. You cannot restart that hundreds of times without huge amount of the starting fuel. And then you don't need the methane anymore/does not make sense to have the complexity to also to be able to burn also methane.

While tricky, I think you are VASTLY overstating the combustion problem. It is in fact possible to ignite hydrocarbon fuels hundreds, thousands, or more times without special ignition fuel. Doesn't your car do it every time you start it?

Reliable microgravity start is of course very difficult, but not an unsolvable problem.

My car takes about on second to start, and coupl of seconds more until I get full thrust or precise thrust control  from it.

That's unacceptable for thruster or emergency exit engine that either is only used for ~0.1 second at a time for precise manouvering(like docking to a space station), or one that has to reach full thrust instantly to escape exploding rocket.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/22/2015 07:55 AM
If on the day SpX closed the deal on LC-39A (14 April 2014) they had installed a half million dollar photovoltaic Sabatier reactor, and ran it non stop at full speed, would they have enough propellant for a BFR launch in 2020?

Fortunately a BFR is not needed on Mars. MCT is big but miniscule compared to BFR so fuel requirement is miniscule too.

Producing methane at the pad feels like a stunt to me. Only the sabatier reactor and electrolysis for hydrogen would be similar. Solar panels, water production and CO2 production are the critical technologies and those would be very different on Mars.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 09/22/2015 07:59 AM
While tricky, I think you are VASTLY overstating the combustion problem. It is in fact possible to ignite hydrocarbon fuels hundreds, thousands, or more times without special ignition fuel. Doesn't your car do it every time you start it?

Reliable microgravity start is of course very difficult, but not an unsolvable problem.

My car takes about on second to start, and coupl of seconds more until I get full thrust or precise thrust control  from it.

That's unacceptable for thruster or emergency exit engine that either is only used for ~0.1 second at a time for precise manouvering(like docking to a space station), or one that has to reach full thrust instantly to escape exploding rocket.

Revving up a ICE is very different and much more complex and time consuming than firing a thruster. The technology of methane thrusters is mature. Just look at any Morpheus video.

But this discussion belongs to another thread.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: philw1776 on 09/22/2015 02:19 PM
If on the day SpX closed the deal on LC-39A (14 April 2014) they had installed a half million dollar photovoltaic Sabatier reactor, and ran it non stop at full speed, would they have enough propellant for a BFR launch in 2020?

Fortunately a BFR is not needed on Mars. MCT is big but miniscule compared to BFR so fuel requirement is miniscule too.

Producing methane at the pad feels like a stunt to me. Only the sabatier reactor and electrolysis for hydrogen would be similar. Solar panels, water production and CO2 production are the critical technologies and those would be very different on Mars.

Yes, MCT will be big.  Maybe up to almost one third the mass of the 1st stage of the BFR.  MCT needs to get lots of Km/sec delta V to function as a SSTO and beyond to escape velocity from Mars' surface even though carrying only a fraction of the "cargo" mass back to the Green Hills of Earth.

/return to topic
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Herb Schaltegger on 09/22/2015 03:11 PM
It would be a fun exercise to go through the process and energy flow diagrams for such a design. 

My colleagues and I did just such analyses 25 years ago for the Space Station Freedom closed-loop ECLSS systems. The necessary info is just basic standard normalized metabolic rates from experimental data combined with chemistry and engineering. How hard could it be? ;)

And if you read the ISS Status Reports in L2 you know I'm being facetious. The engineering is fiendishly tricky to keep going.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Dante80 on 09/22/2015 06:28 PM
A question. After the latest known info about the merlin engine upgrades, has one tried to calculate what would the FH payload capability be for LEO? The site still lists the older numbers.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 09/22/2015 06:36 PM
A question. After the latest known info about the merlin engine upgrades, has one tried to calculate what would the FH payload capability be for LEO? The site still lists the older numbers.

It may not have changed. A lot of the early performance numbers for FH were with v1.1 and FT upgrades in mind.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: deltaV on 09/26/2015 04:11 PM
AFAIK SpaceX has shown no interest in converting Falcon Heavy to use methane. Until that changes methane refining is off-topic in this thread.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 10/01/2015 10:02 PM
Is there anywhere on NSF or elsewhere that outlines what a Mars mission might look like using FHs to assemble something in orbit/send supplies?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: spacenut on 10/01/2015 10:10 PM
I think the talk was for a potentially new metholox upper stage for Falcon Heavy only, say 5m in diameter with higher ISP with say one Raptor vacuum engine or such to get a larger payload to GTO or TMI or the moon.  Boosters would remain the same.  Maybe that should go was on the Raptor, or Mini-BFR thread.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: nadreck on 10/01/2015 10:14 PM
Is there anywhere on NSF or elsewhere that outlines what a Mars mission might look like using FHs to assemble something in orbit/send supplies?

Start here: http://forum.nasaspaceflight.com/index.php?topic=38506.0 (http://forum.nasaspaceflight.com/index.php?topic=38506.0)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MarcAlain on 10/01/2015 10:31 PM
Is there anywhere on NSF or elsewhere that outlines what a Mars mission might look like using FHs to assemble something in orbit/send supplies?

Start here: http://forum.nasaspaceflight.com/index.php?topic=38506.0 (http://forum.nasaspaceflight.com/index.php?topic=38506.0)

I wasn't expecting that much of a discussion, that is fantastic! Thanks!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: oiorionsbelt on 10/13/2015 03:15 PM
Does anyone know if the FH Boosters will be interchangeable or are they right and left.
 Same goes for the center core is it always going to be a center core and can any FH cores be used on an F9?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jarnis on 10/13/2015 03:19 PM
Does anyone know if the FH Boosters will be interchangeable or are they right and left.
 Same goes for the center core is it always going to be a center core and can any FH cores be used on an F9?

AFAIK Center Cores are unique specific to heavy (extra structural reinforcement to handle all that oomph, I guess) while side boosters are effectively standard F9s with a pretty nose cap.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: eriblo on 10/13/2015 03:35 PM
Does anyone know if the FH Boosters will be interchangeable or are they right and left.
 Same goes for the center core is it always going to be a center core and can any FH cores be used on an F9?
Note that that engine layout schematic is inconsistent with the model they use for their renders and video where the right booster is rotated 180 degrees so that all attachment points  are in the same locations (and presumably identical) for both boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 10/13/2015 04:18 PM
AFAIK Center Cores are unique specific to heavy (extra structural reinforcement to handle all that oomph, I guess) while side boosters are effectively standard F9s with a pretty nose cap.

I encountered someone on reddit about this. He claims side boosters and standard F9 are not the same. Confronted with what Gwynne Shotwell said he gets quite agressive and says he knows better, he is building the thrust structures on the factory floor.

My guess is they are both right. They are basically the same but some modification on the thrust structure for the Heavy side booster attachment points. So probably not interchangeabale.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: dror on 10/13/2015 04:27 PM
Does anyone know if the FH Boosters will be interchangeable or are they right and left.
 Same goes for the center core is it always going to be a center core and can any FH cores be used on an F9?

AFAIK Center Cores are unique specific to heavy (extra structural reinforcement to handle all that oomph, I guess) while side boosters are effectively standard F9s with a pretty nose cap.

That's what she said:

 "Falcon Heavy is two different cores — the inner core and the two side sticks,” Shotwell said. “The new Falcon 9 will basically be a Falcon Heavy side booster. So we’re building [only two different] cores to make sure we don’t have a bunch of configurations around the factory so we can streamline operations and hit a launch cadence of one or two a month from every launch site we have.”

 http://spacenews.com/spacex-aims-to-debut-new-version-of-falcon-9-this-summer/

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: MP99 on 10/13/2015 04:40 PM
If booster = core + thrust structure, then they can both be right without being inconsistent with each other.

Though, TBH, I don't think this is actually SpaceX's usage.

The "basically" in Gwynne's statement is sufficient for this anyway, ISTM.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: randomly on 10/13/2015 05:31 PM
If the FH boosters are not mirror imaged, how do they handle umbilicals and fueling?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 10/13/2015 05:38 PM
If the FH boosters are not mirror imaged, how do they handle umbilicals and fueling?

They are mirrored.

EDIT: What I meant to say is that they are identical (not mirrored), just clocked/rotated 180 degrees.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: randomly on 10/13/2015 05:48 PM
so they are NOT the same cores... just similar.
It would be interesting to find out what Shotwell  actually meant...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Doesitfloat on 10/13/2015 06:00 PM
The graphic on the SpaceX website shows boosters that are anything but mirrored.
If they were mirrored we would see identical exterior features on each booster. 
Since they are different-- all we can say is they are not mirrored. They may be identical but we don't know.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 10/13/2015 06:03 PM
The graphic on the SpaceX website shows boosters that are anything but mirrored.
If they were mirrored we would see identical exterior features on each booster. 
Since they are different-- all we can say is they are not mirrored. They may be identical but we don't know.

D'oh. I said mirrored but I meant identical. The left one is the same as the right one, but rotated 180 degrees. Sorry for the confusion.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: TomH on 10/13/2015 06:32 PM
Is there anywhere on NSF or elsewhere that outlines what a Mars mission might look like using FHs to assemble something in orbit/send supplies?

Start here: http://forum.nasaspaceflight.com/index.php?topic=38506.0 (http://forum.nasaspaceflight.com/index.php?topic=38506.0)

I wasn't expecting that much of a discussion, that is fantastic! Thanks!

Also:

http://forum.nasaspaceflight.com/index.php?topic=35529.0

http://forum.nasaspaceflight.com/index.php?topic=23970.0

http://forum.nasaspaceflight.com/index.php?topic=14537.0

http://forum.nasaspaceflight.com/index.php?topic=24842.0

Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: enzo on 12/30/2015 02:49 AM
Want to bring this thread back for the new year, perhaps the year of FH.

Let's say there are a handful of landed stages by the time FH is ready to fly (likely), and at least one has been reflown successfully (maybe). Do you think recovered first stages can undergo whatever modifications necessary for use as side boosters (minor, as claimed)? If so, will FH demo flight use reflown boosters for cost savings?

One argument against is that part of developing FH is building at least one, including side boosters, from scratch. But that's irrelevant if they're nearly identical to first stages. Another is that perhaps reflight will have been shown, but not enough times to prove reliable for the high-profile FH demo.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Robotbeat on 12/30/2015 02:51 AM
No. You'll save money by just using the recovered stages unaltered for more F9 flights. They've already started building the Falcon Heavy, and at this point they frankly can't afford a potential new problem to show up on this already-complicated vehicle.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Lars-J on 12/30/2015 04:00 AM
Want to bring this thread back for the new year, perhaps the year of FH.

Let's say there are a handful of landed stages by the time FH is ready to fly (likely), and at least one has been reflown successfully (maybe). Do you think recovered first stages can undergo whatever modifications necessary for use as side boosters (minor, as claimed)? If so, will FH demo flight use reflown boosters for cost savings?

One argument against is that part of developing FH is building at least one, including side boosters, from scratch. But that's irrelevant if they're nearly identical to first stages. Another is that perhaps reflight will have been shown, but not enough times to prove reliable for the high-profile FH demo.

It depends... According to a SpaceX'er on Reddit (seems legit), the octaweb for an FH side booster is slightly different from the current F9 octaweb. But what is not clear is if the F9's going forward after FH first flight will have that same octaweb configuration. So... Current F9's cannot be used as FH side boosters. But future F9's *may* be interchangeable with FH side boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: sdsds on 12/30/2015 04:12 AM
Want to bring this thread back for the new year, perhaps the year of FH.

Whole-hearted agreement here! This should be they year of the Falcon Heavy!

[1] You'll save money by just using the recovered stages unaltered for more F9 flights.

[2] they frankly can't afford a potential new problem to show up on this already-complicated vehicle.

Again whole-hearted agreement on [2]: it sure seems like for the first few FH flights the rule to follow should be "keep it as simple as possible."

As for [1], I agree that if they can save money by reusing recovered and refurbished F9FT stages, they should definitely do so! But even if due to structural issues they can "only" reuse the Merlin engines, wouldn't that alone provide justification for the RTLS powered landing approach? (After all, that's essentially what ULA is claiming re: Vulcan....)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: macpacheco on 12/30/2015 06:16 AM
Methinks a new, fully reusable, methane fueled launcher powered by Raptors or Raptor variants will replace both F9 and FH. Larger payloads migrate to BFR.

Where does that leave the loads of progressively smaller satellites they would need to launch to make money?

Not a problem as long as Raptor based rockets are able to achieve full reuse in the order of 100x.
As long as expendables on the Eagle lite cost a few million, with 100 launches, even if Eagle lite costs 10x as a F9R, that would still be much cheaper than a F9R FT wasting the 2nd stage.
Doing bulk launches doesn't mean a fully loaded rocket is required. Customers would pay based on how much of a hurry they are in. As low as sub US$ 10 million if they could wait 6 months, or half the current F9R FT launch prices if they want to launch in a hurry. This would also incentive customers to build multiple birds and launch them together.
With a full reuse rocket, integrating the fairing and an upgraded dispenser ring might make sense.

The bread and butter of the launch market is still GTO and ISS destinations. GTO launches can be aggregated easily, can't them ? Plus perhaps hurried launches to GTO could be delivered directly to GEO or near GEO ? How much would that be worth in extra launch value ?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: guckyfan on 12/30/2015 07:27 AM
The bread and butter of the launch market is still GTO and ISS destinations. GTO launches can be aggregated easily, can't them ? Plus perhaps hurried launches to GTO could be delivered directly to GEO or near GEO ? How much would that be worth in extra launch value ?

True for GTO as bread and butter. Going directly to GEO not so much. Doing it with Falcon Heavy leaves the upper stage stranded there, another big piece of space junk. Doing it with BFR would require a fully LEO refuelled vehicle for even a few com sats, so 4 or 5 launches including tankers. The delta-v for going to GEO and back with a heavy upper stage/MCT is huge, more than going to Mars and landing there.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Ben the Space Brit on 12/30/2015 11:31 AM
Something I've been puzzling over: Are there any differences, structurally, between the F9 v.1.2 core and the FH outboards? I'm wondering if one of the markets for reused cores might be to reduce FH production costs.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Jcc on 12/30/2015 11:39 AM
Something I've been puzzling over: Are there any differences, structurally, between the F9 v.1.2 core and the FH outboards? I'm wondering if one of the markets for reused cores might be to reduce FH production costs.

Yes, the center core is structurally reinforced to bear more loading.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 3)
Post by: Chris Bergin on 12/30/2015 11:56 AM
On to thread 4!
http://forum.nasaspaceflight.com/index.php?topic=39181.0