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SpaceX Vehicles and Missions => SpaceX Mega Thread Archive Section => Topic started by: Chris Bergin on 08/07/2014 11:01 am

Title: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Chris Bergin on 08/07/2014 11:01 am
Big thread 1, so time for thread 2:

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

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/


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 - Now in its own dedicated all-vehicle section:
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 2)
Post by: TrevorMonty on 08/07/2014 01:02 pm
If the plan is to use FHR for > 3.5t GTO payloads and F9R for < 3.5t. SpaceX needs to make the FHR cheaper than F9E otherwise there is no incentive for customer to use FHR over F9E for the 3.5-4.8t payloads.  FHR will need to be < $63m which will also force a price reduction in F9R flights.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jet Black on 08/07/2014 03:40 pm
Is there a likely orbit that they will use for the first Heavy launch to demonstrate its capability? Similarly are they likely to give it a payload, or simply show that it behaves as expected?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: symbios on 08/07/2014 03:41 pm
Since single digit (millions) has been mentioned as a possibility for the F9R I would think that it would not be that hard to price the FH below the F9 expendable...  :P

I would have priced it a lot higher because I think the market could take it. But Musk wants to change the market and open it up for new possibilities. So he will lower it as far as he can to make that happens. The question is under what time frame he will lower the prices...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: JasonAW3 on 08/07/2014 06:05 pm
Since single digit (millions) has been mentioned as a possibility for the F9R I would think that it would not be that hard to price the FH below the F9 expendable...  :P

I would have priced it a lot higher because I think the market could take it. But Musk wants to change the market and open it up for new possibilities. So he will lower it as far as he can to make that happens. The question is under what time frame he will lower the prices...

I'm not sure that the launch cost for the F9R will start out in the single digit millions, as SpaceX will want to recoop their manufacturing costs on that rocket as quickly as possible.  Of course, after the F9R has a proven track record of relaunches, I have little doubt that they should be able to bring the cost down to about where you stated.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ey on 08/07/2014 06:18 pm
Getting F9R to single-digit millions will require a reusable second stage, which is a ways off right now. FHR could see a bigger cost reduction, percentagewise, since it has three boosters and only one second stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 08/07/2014 06:44 pm
Best to limit discussions to 1st stage recovery only, 2nd recovery is still an unknown for now.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 08/07/2014 07:21 pm
Since single digit (millions) has been mentioned as a possibility for the F9R I would think that it would not be that hard to price the FH below the F9 expendable...  :P

I would have priced it a lot higher because I think the market could take it. But Musk wants to change the market and open it up for new possibilities. So he will lower it as far as he can to make that happens. The question is under what time frame he will lower the prices...

I'm not sure that the launch cost for the F9R will start out in the single digit millions, as SpaceX will want to recoop their manufacturing costs on that rocket as quickly as possible.  Of course, after the F9R has a proven track record of relaunches, I have little doubt that they should be able to bring the cost down to about where you stated.

If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 

If a competitor improves and gets cheaper than lower your price but not until you have too.

I think SpaceX's currently low  pricing has 2 purposes, it shows that you are backing up your claims that your dramatically cheaper and it entice customers to a new company and vehicle.  They recently raised their prices and I think they could raise their prices more once F9 is proven if they are still cheap enough to be awarded launches.  Early F9R launches will likely be a reduced price because of uncertainty with previously flown vehicles.  But that eventually it may not be much different than F9 prices.

Key to further pricing reduction will be 2nd stage recovery which the F9R will enable.  That's going to be fun to see develop.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Elmar Moelzer on 08/07/2014 07:41 pm
If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 
I think that they will try to keep the cost of launches just low enough that they can keep their development and production going at current rates. In order for RLVs to make sense, they need a high launch rate. In order to get a high launch rate, they need more customers. In order to get more customers, they need to lower prices, dramatically.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: groundbound on 08/07/2014 09:08 pm

If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 

If a competitor improves and gets cheaper than lower your price but not until you have too.
<snipped>

Perhaps even smarter is at some point to start a special program offering deeply discounted launches to a few customers that are in some sort of startup mode. That way you help accelerate new business models while harvesting as much revenue from existing business.

Make this public and smaller/risky businesses might try to form their businesses around it. All SpaceX has to do is sell a few launches at cost for the lottery ticket of maybe eventually getting a new customer sector (who would eventually pay full freight.)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: CuddlyRocket on 08/08/2014 06:43 am

If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 

If a competitor improves and gets cheaper than lower your price but not until you have too.
<snipped>

Perhaps even smarter is at some point to start a special program offering deeply discounted launches to a few customers that are in some sort of startup mode. That way you help accelerate new business models while harvesting as much revenue from existing business.

Make this public and smaller/risky businesses might try to form their businesses around it. All SpaceX has to do is sell a few launches at cost for the lottery ticket of maybe eventually getting a new customer sector (who would eventually pay full freight.)

Alternatively, provide a lower cost launch in return for some shares or other economic interest in the new venture. If it fails, SpaceX covered its costs and if it succeeds it gains another source of income.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Mader Levap on 08/08/2014 11:50 am
They recently raised their prices and I think they could raise their prices more once F9 is proven if they are still cheap enough to be awarded launches.  Early F9R launches will likely be a reduced price because of uncertainty with previously flown vehicles.  But that eventually it may not be much different than F9 prices.
If that (reusable for almost same price as expendable) happens, Musk failed according to his very own criteria.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: newpylong on 08/08/2014 12:44 pm
Single digits is a pipe dream. They won't be able to pay the employees let alone keep the lights on.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nomadd on 08/08/2014 01:11 pm
 A lot of people sound like Henry Ford's bankers. Musk doesn't believe the way to success is to maximize profit for every launch. He's trying to create a whole new market, many times the size of the present one with lower prices. Comsats, for instance, are hugely expensive and long lived largely because of launch prices. If it cost $10 million to replace one instead of $100 million, the whole game would change. Same for DOD payloads, despite the insistence of some that nothing can ever be any different than it's always been. Cheap, fast response launches would create an entirely new market for on demand assets. Repositioning one of those $1 billion monsters to get some photos is rarely practical.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 08/08/2014 07:48 pm

If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 

If a competitor improves and gets cheaper than lower your price but not until you have too.
<snipped>

Perhaps even smarter is at some point to start a special program offering deeply discounted launches to a few customers that are in some sort of startup mode. That way you help accelerate new business models while harvesting as much revenue from existing business.

Make this public and smaller/risky businesses might try to form their businesses around it. All SpaceX has to do is sell a few launches at cost for the lottery ticket of maybe eventually getting a new customer sector (who would eventually pay full freight.)
Might be simpler to offer deep discounts to customers that buy a large number of flights - EG multiple flights per year to a Bigelow station.

Once it looks like they have solid increased demand out to their planning horizon, they might re-base their standard prices.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 08/08/2014 10:30 pm
For the existing satellite market,  slightly lower prices eg $50m than their current prices would give them lion share and still make a good profit.
In case of Bigelow dropping seat prices from the current $26m to $10-15m should significantly. expand the market.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: jamesh9000 on 08/09/2014 07:13 pm
Hi. First time poster, long time lurker. I've done a search for my query but can't seem to find anything, so forgive me if this has already been speculated on, (because I'm sure it has), but what do you think of the idea that the first FH demonstration flight will be in the reusable configuration? That might account for its continued slippage to 2015 with no actual booked flight in sight.

Just imagine: they get the barge landing down and relaunch a falcon 9 core early 2015, and then, a few months later they fly an FHR then refly it again just to show they can. In one go America gets their heaviest lift vehicle since Saturn V and, oh yeah, its reusable. And suddenly ULA is pretty much obsolete. Its just the sort of big, press-making opportunity Musk loves. What do you think?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 08/09/2014 08:00 pm
I think FH is on track. The F9v1.1 had to work first and that's been less than a year.

Additionally I suspect they were waiting to get 39A under there control and built first.

It's a different vehicle than the F9. Just because it looks like 3 F9's squished together doesn't mean it's as easy as building 3 F9's.

These things take time.  Re-using the boosters, even if it's just the outside 2 may depend more on an FAA permission to land  and landing pads than the ability to do so. I'd be surprised if they wait for that.  They have certification for the Feds and paying customers that want to see it work before they hand over the dough.

I see barge landings as a demonstration not direct reuse.  That's going to be a tricky feat to get it down and back to port.  Maybe not impossible but certianly a few very interesting pieces of equipment and procedures and people in very close proximity to an active rocket.  Which is usually not recommended.

SpaceX, when the FH launches, regardless of re-useability is going to make the cost and schedule of SLS (built from existing parts) look horrid.

I want the FH to succeed wildly and be fully reusable.  Maybe we'll know in a years time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: billh on 08/09/2014 09:56 pm
Hi. First time poster, long time lurker. I've done a search for my query but can't seem to find anything, so forgive me if this has already been speculated on, (because I'm sure it has), but what do you think of the idea that the first FH demonstration flight will be in the reusable configuration? That might account for its continued slippage to 2015 with no actual booked flight in sight.

Just imagine: they get the barge landing down and relaunch a falcon 9 core early 2015, and then, a few months later they fly an FHR then refly it again just to show they can. In one go America gets their heaviest lift vehicle since Saturn V and, oh yeah, its reusable. And suddenly ULA is pretty much obsolete. Its just the sort of big, press-making opportunity Musk loves. What do you think?

Well, I doubt that accounts for the delay, but it's an interesting question. I don't see a strong reason why the first FH flight would not attempt at least a soft splashdown on all three cores. Maybe the software wouldn't be ready. Maybe they wouldn't want the distraction. But it seems they could certainly outfit the cores with legs and fins for the first flight if they wanted to.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 08/09/2014 10:49 pm
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time. Thus, it should not be un expected that all three cores might be recovered.
Now, first they have to convince Range that flying three 50m towers at the same time is perfectly safe and there's no chance of collisions. So, unless they do a dance of F9R-Dev1/2/3 in NM, it will be a tough ssale.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: newpylong on 08/09/2014 11:01 pm
I think FH is on track. The F9v1.1 had to work first and that's been less than a year.

Additionally I suspect they were waiting to get 39A under there control and built first.

It's a different vehicle than the F9. Just because it looks like 3 F9's squished together doesn't mean it's as easy as building 3 F9's.

These things take time.  Re-using the boosters, even if it's just the outside 2 may depend more on an FAA permission to land  and landing pads than the ability to do so. I'd be surprised if they wait for that.  They have certification for the Feds and paying customers that want to see it work before they hand over the dough.

I see barge landings as a demonstration not direct reuse.  That's going to be a tricky feat to get it down and back to port.  Maybe not impossible but certianly a few very interesting pieces of equipment and procedures and people in very close proximity to an active rocket.  Which is usually not recommended.

SpaceX, when the FH launches, regardless of re-useability is going to make the cost and schedule of SLS (built from existing parts) look horrid.

I want the FH to succeed wildly and be fully reusable.  Maybe we'll know in a years time.

 ::)
This is not on topic but SLS does not use "existing parts" save for 4 flights of RS-25.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: GregA on 08/11/2014 02:42 am
If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 

If a competitor improves and gets cheaper than lower your price but not until you have too.

Yes they have to fund their Mars projects :) The combination of showing they CAN do cheap spaceflight plus they can make a healthy profit will interest some. Still it's no wonder Musk doesn't want to float SpaceX until all the pieces are well and truly in place!

On another note, SpaceX might be in the interesting position of setting their price as 30% cheaper (or whatever) than any competitor. If the competitor tries to match their price they know SpaceX will reduce another 30% because they can and have said they will, so the competitor will not reduce until they know their own costs are sustainable.

In any case, customers are going to pay more for "first use" rockets (for now, as the competitors will spin that as being less risk), and pay more for expendable ("last use") rockets for their extra launch mass. The "regular use" launches will be the cheapest.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: GregA on 08/11/2014 02:43 am
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time.
Is it official that the first FH won't have cross feeding?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Llian Rhydderch on 08/11/2014 04:08 am

In any case, customers are going to pay more for "first use" rockets (for now, as the competitors will spin that as being less risk), and pay more for expendable ("last use") rockets for their extra launch mass. The "regular use" launches will be the cheapest.

I don't know that this is the way its going to work out...

...but I like your theory; and I think you've advanced the discussion here by advancing it.

The mid-term market for space launch does look like it might birfurcate (trifurcate?) into the sort of product offering distinctions you've articulated here.  And if the terms catch on, we will all know GregA @ NSF said it first:  the "first use"/"last use"/ "regular use" pricing model of space launch in the late 2010s.   ;D
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: douglas100 on 08/11/2014 10:28 am
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

Quote
Now, first they have to convince Range that flying three 50m towers at the same time is perfectly safe and there's no chance of collisions.

Agree with that. It would be a sight to behold.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cambrianera on 08/11/2014 11:55 am
The discussion on Jon Goff's MAC on Reusable Second Stage Configuration thread http://forum.nasaspaceflight.com/index.php?topic=32180.msg1232404#msg1232404 made me think that such a system could also be applied to center stage of heavy.
Eliminating 2000-3000 m/s of DV from the core before starting the boostback burn could be an advantage in term of payload.
The MAC system should be lighter than the propellant needed for the braking part of the burn (about 20-25 ton).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 08/11/2014 12:16 pm
The discussion on Jon Goff's MAC on Reusable Second Stage Configuration thread http://forum.nasaspaceflight.com/index.php?topic=32180.msg1232404#msg1232404 made me think that such a system could also be applied to center stage of heavy.
Eliminating 2000-3000 m/s of DV from the core before starting the boostback burn could be an advantage in term of payload.
The MAC system should be lighter than the propellant needed for the braking part of the burn (about 20-25 ton).

I don't know how useful it would be for boostback. It will travel forward during deceleration. But it should help a lot for downrange recovery. It could reduce the payload penalty for the core to the MAC, the landing legs and landing fuel, which would be quite small.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 08/11/2014 12:57 pm

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage. I've calculated a 10% extra propellant. When I did the numbers for typical MaxQ and throttling at 70%, hey burned about the same time. Elon might have said that 60% was possible, which might give the core more time, though.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 08/11/2014 01:43 pm

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage. I've calculated a 10% extra propellant. When I did the numbers for typical MaxQ and throttling at 70%, hey burned about the same time. Elon might have said that 60% was possible, which might give the core more time, though.

FH carries a bigger payload than F9 - call it (53-13)/2 = 20t per booster (eventually). The core & u/s may also have some additional dry mass over F9 to cope with the greater payload.

9x M1D on F9 core also lifts interstage, 200klb u/s prop, u/s burnout mass, payload adapter, up to 13t of payload, and PLF.

Other than the 20t+ for extra payload & dry mass, all of that extra mass needs to be replaced by prop to keep liftoff T:W the same.

ISTM 80t+ per booster, which is more like 20%?



But, there is also an argument that there must be some prop remaining at booster MECO (BECO?), at least when operating in expendable mode.

F9 has to throttle to keep G-levels OK (call it 5G - doesn't matter if that's a bit out).

If all 27 engines remain burning until some combined MECO event, I don't see how G-levels could stay anywhere near 5G.

Of course, if you're recovering the boosters, then they will BECO with some prop mass remaining, which would help keep the G levels in check. So, this is more an argument for how it couldn't work (27 engine cut-out) in expendable mode.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: douglas100 on 08/11/2014 03:50 pm

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage...

Oops! Forgot that! You're correct.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Elmar Moelzer on 08/11/2014 05:25 pm
But isn't the interstage where the cold gas thrusters and some of the other equipment (avionics, etc) are located? If they fill the entire interstage with tanks, where do these things go?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: corrodedNut on 08/11/2014 07:00 pm
But isn't the interstage where the cold gas thrusters and some of the other equipment (avionics, etc) are located? If they fill the entire interstage with tanks, where do these things go?
The boosters will have nosecones that serve the same purpose.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lobo on 08/11/2014 10:57 pm
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time. Thus, it should not be un expected that all three cores might be recovered.
Now, first they have to convince Range that flying three 50m towers at the same time is perfectly safe and there's no chance of collisions. So, unless they do a dance of F9R-Dev1/2/3 in NM, it will be a tough ssale.

I'd expect an attempted RTLS recovery of the outboard boosters if they've already successfully demonstrated that with F9R.  And then either an expended central core, or a water landing somewhere downrange to test the effects of reentry from that altitude and speed on it.

I think going from RTLS one core to 3 might be a big jump all at once.  Try two, and then on the next flight try all three.  Meanwhile they have telemetry on what the central core does which will be useful for them later if they want to try to recover the central core downrange somehow.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 08/12/2014 06:07 pm
I have a question for our community.

If the FH is going to fly from KSC in 2015, when do you think we will see it on a test stand in McGregor and what would you expect the testing there to be?

I think probably 6 months before scheduled launch
Tests starting with simple static fire for a few seconds gradually building to longer burns that include the core throttling down and simulated separation of the side boosters. 

A full duration burn would be reasonable but can they support a full FH burn on the stand with regards to their permits and deluge system?

Edit: Spelling
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: CraigLieb on 08/12/2014 06:32 pm
I have a question for our community.

If the FH is going to fly from KSC in 2015, when do you think we will see it on a test stand in McGregor and what would you expect the testing there to be?
...

Adjunct questions:
  - Has anyone outside of SpX seen FH Stage 1 cores in production? 
  - Would two of the S1 cores be identifiable as FH due to their increased length?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Moe Grills on 08/14/2014 07:16 pm
Is there a likely orbit that they will use for the first Heavy launch to demonstrate its capability? Similarly are they likely to give it a payload, or simply show that it behaves as expected?

How about a parabolic/extreme elliptical orbit that would take a mockup or a 'boilerplate' version of the Dragon on a cislunar flyby? Of course it is not going to happen; Elon Musk does not like carrying out stunts for stunt's sake. And besides, does Elon care what anybody says here on this forum?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Karloss12 on 08/14/2014 08:15 pm
Does anyone want to bet that the FH initial flight will be delayed until the cores can be recovered?

Or would that delay be to long?

Or will there be no need for a delay as cores will recovered by early 2015?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: AJW on 08/14/2014 09:54 pm
I believe that the first priority was to prove the ability to meet existing demand and clear some of the F9 backlog.  This has required both clearing technical launch hurdles and removals of bottlenecks in the production line.  Given a choice between clearing three paying commercial launches, or launching one FH test flight seems straight forward when the first paid FH launch isn't planned until late 2015 or even 2016.  Having recoverable cores dovetails nicely with the current timeline and I would think that if production is truly ramped up, if launch issues are resolved, if core recovery is proven in the next few launches, then at least two of the FH cores should be recoverable.  That is still a lot of "if's"
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Mader Levap on 08/15/2014 12:22 am
Does anyone want to bet that the FH initial flight will be delayed until the cores can be recovered?
I doubt that they would slip FH over it, if they could not reliably recover stages by then for some reason.

Or will there be no need for a delay as cores will recovered by early 2015?
If they are lucky (read: successful stage recovery relatively soon, first FH launch relatively late), indeed they could try to recover at least two out of three first stages of FH on first flight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 08/15/2014 01:54 am

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage. I've calculated a 10% extra propellant. When I did the numbers for typical MaxQ and throttling at 70%, hey burned about the same time. Elon might have said that 60% was possible, which might give the core more time, though.

FH carries a bigger payload than F9 - call it (53-13)/2 = 20t per booster (eventually). The core & u/s may also have some additional dry mass over F9 to cope with the greater payload.

9x M1D on F9 core also lifts interstage, 200klb u/s prop, u/s burnout mass, payload adapter, up to 13t of payload, and PLF.

Other than the 20t+ for extra payload & dry mass, all of that extra mass needs to be replaced by prop to keep liftoff T:W the same.

ISTM 80t+ per booster, which is more like 20%?



But, there is also an argument that there must be some prop remaining at booster MECO (BECO?), at least when operating in expendable mode.

F9 has to throttle to keep G-levels OK (call it 5G - doesn't matter if that's a bit out).

If all 27 engines remain burning until some combined MECO event, I don't see how G-levels could stay anywhere near 5G.

Of course, if you're recovering the boosters, then they will BECO with some prop mass remaining, which would help keep the G levels in check. So, this is more an argument for how it couldn't work (27 engine cut-out) in expendable mode.

cheers, Martin
Youre calculating wrong. If you use the 52t figure for FH, Falcon 9 v1.1 should be given the 16t to LEO figure in the NLS II contract. Those two figures were released at the same time, so it seems likely to me they have the same assumptions behind them.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 08/15/2014 08:54 am
OK, but that just increases the prop load on each booster by another 1.5t, when I was suggesting a bigger booster prop load, anyway.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: UberNobody on 08/24/2014 11:12 pm
Has anyone compiled a list of payload capability for Falcon Heavy?
Crossfeed vs no crossfeed, reusable vs expendable, LEO vs GTO etc?

Would be nice to have it all down in one place, what we know and what we don't know (and what we can guess).

Thanks in advance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 08/25/2014 02:33 am
Has anyone compiled a list of payload capability for Falcon Heavy?
Crossfeed vs no crossfeed, reusable vs expendable, LEO vs GTO etc?

Would be nice to have it all down in one place, what we know and what we don't know (and what we can guess).

Thanks in advance.

I don't have the numbers to produce a chart.  But I suggested a while ago that a plot be plotted, for a given inclination,  of payload mass versus altitude for he F9R, F9E, FHR, FHE, FHCF (or whatever all the possible FH combinations are, seems like many, if you get into crossfeed, partially reuseable, RTLS, Downrange recovery etc.)

Something like 4 or 5 different colors lines on an excel chart.  That could help a lot, but perhaps just lead to more debate.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 08/25/2014 03:05 am
Most of this information is in the thread if go back a few weeks. Alternatively try Wikipedia.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Crews on 08/26/2014 05:38 pm
Began following this discussion about midway through first thread-- with Boca Chica launch site, and followed since.

My question/thoughts...

Do we have any idea of the range of Falcon's (and Heavy) s1 boost?

For reusable, returning Falcon shot from Texas Coast, I am supposing that a near equivalent for first stage boost is the Saturn V, S1-- for about 400 miles/650 km, horizontal, from launch to splash.

That would place the boost phase plus momentum to surface of S1 almost due south of New Orleans-- the nearest land, and which is connected to Gulf Intracoastal Waterway back to Brownsville. 

Would not that be more efficient than a flying the return to Boca Chica (and more feasible than any attempt to reach Cape Canaveral-- as some had suggested)?

Otherwise, a floating platform would seem most cost effective for a landing site.

Then again, the Saturn comparison may not be close-- huge payload.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 08/26/2014 09:05 pm
...
Do we have any idea of the range of Falcon's (and Heavy) s1 boost?

For reusable, returning Falcon shot from Texas Coast, I am supposing that a near equivalent for first stage boost is the Saturn V, S1-- for about 400 miles/650 km, horizontal, from launch to splash.

That would place the boost phase plus momentum to surface of S1 almost due south of New Orleans-- the nearest land, and which is connected to Gulf Intracoastal Waterway back to Brownsville. 

Would not that be more efficient than a flying the return to Boca Chica (and more feasible than any attempt to reach Cape Canaveral-- as some had suggested)?
...
Not going to happen. To many populated areas along the flight path and around landing zone.

The authorities will have a very dim view of any large ballistic reentry objects near a metropolitan area like New Orleans.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Crews on 08/27/2014 12:16 am
Not going to happen. To many populated areas along the flight path and around landing zone.

The authorities will have a very dim view of any large ballistic reentry objects near a metropolitan area like New Orleans.

Right.  Let me try again.

Brownsville is to Boca Chica as New Orleans is to [blank].  Lots of unused coastal, but channel accessible, land.  You need a landing pad/area, a crane, a tug and barge; and preferable, I would think, to a mid-Gulf platform as has been suggested.

What I am trying to discern is what are the abilities and likely geographic resources for the reusable Falcons flown out of Boca Chica.  It may be that all the way back to Boca Chica is what is intended.

Besides range of the S1, I'm also interested in launch declinations.  Think maybe I should take these questions to the Boca Chica thread-- but, in essence, they really are Falcon Heavy specific as the answers must be built on it's first stage abilities, both in boost and in return ranges.

And those, I have not read or seen discussed.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dglow on 08/27/2014 01:48 am
Not going to happen. To many populated areas along the flight path and around landing zone.

The authorities will have a very dim view of any large ballistic reentry objects near a metropolitan area like New Orleans.

Right.  Let me try again.

Brownsville is to Boca Chica as New Orleans is to [blank].  Lots of unused coastal, but channel accessible, land.  You need a landing pad/area, a crane, a tug and barge; and preferable, I would think, to a mid-Gulf platform as has been suggested.

What I am trying to discern is what are the abilities and likely geographic resources for the reusable Falcons flown out of Boca Chica.  It may be that all the way back to Boca Chica is what is intended.

Besides range of the S1, I'm also interested in launch declinations.  Think maybe I should take these questions to the Boca Chica thread-- but, in essence, they really are Falcon Heavy specific as the answers must be built on it's first stage abilities, both in boost and in return ranges.

And those, I have not read or seen discussed.

Crews, I think I see where you're going/what you're asking, and I'm fairly certain it has been discussed. There is so much great discussion around here, it is difficult to follow all being said and nigh-impossible to come up-to-speed on that already said. The archives are deep, so no harm no foul.

Aside: if someone ever invents a magic piece of machine learning which generates summary-conclusions of online discussion... a 'here's the latest we know and how we got here, as well as the the most current-and-well-supported speculation' machine... well, NSF would be the place to beta-test it.

To your question: AFAIK, the only potential non-RTLS (non-Boca Chica) landing site for Boca Chica launches which has been realistically considered is the Florida Keys  and even then, only in the context of much larger, largely-theoretical rockets that SpaceX may build in the future. For F9 and FH launches, the Keys are too distant.

Launches from Boca Chica cannot cross over land and therefore must route between Florida and the Caribbean islands  what's called a dogleg maneuver. As such, New Orleans does not seem a likely landing site. More recently, some have speculated about the use of mobile landing platforms, e.g. barges, oil rigs, etc.

(All: please add to and/or correct this summary as best seen fit.)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Darkseraph on 08/27/2014 02:29 am
I'm by no means an expert and I'm pulling this opnion out of the quantum vacuum fluctuations.....but I'll say it here. I don't think Falcon Heavy will be used for very many missions in the long run, esp if large methane engines are developed and first stage re-usability is proven doable and cost effective.


My haphazard reasoning goes that, nearly every Falcon launch so far has had problems. This vehicle has about three times as many potential problems thanks to its design. Landing a single core back on land is an impressive feat, but having that many stage separation and 3 core landings with 27 engines running perfectly sounds like a bridge too far and that a good few of them will fail.

In my mind, if they could prove reusability for the F9R and can successfully develop a large SC Methane engine, it might be better just to design a 5 meter core, 2 stage methane launcher with far fewer engines than 27 that can lift the largest plausible military and commercial commsats that will be needed in the next 15 years. Whatever there multiplanetary life plans are, those kinda of missions are going to be their bread and butter and it might be worth making a simpler reusable vehicle scaled for them that tests MCT technology before committing to things bigger than Saturn V. Such a vehicle doesn't even need to lift a ridiculous number to LEO like 53 tons or 20 odds ones to GTO, but could get more volume for mass than FH, making several possible lunar and neo missions a lot less hard to design. Given the current Raptor stats, such a vehicle might only need between 2 and 4 engines, or perhaps 9 if it was a smaller derivative of that technology.

That Golden Spike lander looks horrendous for the astronauts and basically not sustainable past the first few missions.

Anyway, I'm sure there are people here that are better with the numbers than me and could give specs for a more optimal vehicle.

EDIT: Okay, essentially what I'm advocating is something similar to the Falcon X that was proposes with a roughly similar diameter and engine count. That could put a good 38 tons into LEO with a 6 metre diameter, without being reusable or the higher ISP of methane. I suspect a similar vehicle, but with reusable with methane, given the payload hit would still be able to launch just about any Satellite of the near future and land back at the site with both stages.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 08/27/2014 08:30 am


Began following this discussion about midway through first thread-- with Boca Chica launch site, and followed since.

My question/thoughts...

Do we have any idea of the range of Falcon's (and Heavy) s1 boost?

For reusable, returning Falcon shot from Texas Coast, I am supposing that a near equivalent for first stage boost is the Saturn V, S1-- for about 400 miles/650 km, horizontal, from launch to splash.

That would place the boost phase plus momentum to surface of S1 almost due south of New Orleans-- the nearest land, and which is connected to Gulf Intracoastal Waterway back to Brownsville. 

Would not that be more efficient than a flying the return to Boca Chica (and more feasible than any attempt to reach Cape Canaveral-- as some had suggested)?

Otherwise, a floating platform would seem most cost effective for a landing site.

Then again, the Saturn comparison may not be close-- huge payload.

Elon has said that FH's core will overshoot Florida. (Not sure if that's only for the crossfeed version.)

Assuming that, most efficient mission design should be a braking burn shortly after MECO (in place of the boostback burn for F9 / FH boosters).

The advantage of this is that any speed reduction here will reduce size of the reentry burn.

ISTM the question is whether to land on East, South or West coasts of Florida. South is probably the lowest dV penalty, and easiest to avoid the IIP crossing Florida during the post-MECO burn.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: llanitedave on 08/28/2014 03:32 pm
I was pretty sure that it was agreed that the core would undershoot Florida.  My memory might be faulty, though.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 08/28/2014 05:07 pm
I was pretty sure that it was agreed that the core would undershoot Florida.  My memory might be faulty, though.

Same with me on both parts. Undershoot the keys, that is. Overshooting would be good, though. They would have to do a brake/reentry burn and can chose the final touchdown point in a wide range with almost the same amount of fuel.

BTW Garrett Reisman seemed to know very little about Falcon Heavy in his presentation but he stated clearly, that FH would not be manrated, at least initially.

IMO it should not be too hard to add that capability, when required.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 08/28/2014 06:49 pm
I was pretty sure that it was agreed that the core would undershoot Florida.  My memory might be faulty, though.

Quote from: https://twitter.com/yatpay/statuses/330394578442133504
Is it possible to launch from Texas and land in Florida?

Quote from: https://twitter.com/elonmusk/statuses/330395232564826112
Side boosters fall short & center core goes too far + Florida is heavily populated. Landing permission tricky :)

Edit: if they can afford the sideways divert (and keep the IIP off land during the divert burn), they will have permission to land cores at CCAFS.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars_J on 08/28/2014 06:55 pm
Quote from: https://twitter.com/elonmusk/statuses/330395232564826112
Side boosters fall short & center core goes too far + Florida is heavily populated. Landing permission tricky :)

Edit: if they can afford the sideways divert (and keep the IIP off land during the divert burn), they will have permission to land cores at CCAFS.

That would be a *massive* sideways divert, that would take the IIP across many shipping lanes and flight corridors. (Can you imagine closing all that down?) That's not going to happen unless they can prove an exceptional safety record.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 08/28/2014 07:12 pm
Quote from: https://twitter.com/elonmusk/statuses/330395232564826112
Side boosters fall short & center core goes too far + Florida is heavily populated. Landing permission tricky :)

Edit: if they can afford the sideways divert (and keep the IIP off land during the divert burn), they will have permission to land cores at CCAFS.

That would be a *massive* sideways divert, that would take the IIP across many shipping lanes and flight corridors. (Can you imagine closing all that down?) That's not going to happen unless they can prove an exceptional safety record.

Had only thought about avoiding land, but sounds reasonable.

Will they have to clear shipping out of the "thread the needle" South of Florida?

Would it then be a relatively small extra imposition to transition across to a landing on the Southern tip of Florida?

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: watermod on 08/28/2014 07:54 pm
From the fiso mp3 it is obvious that the plumbing is different on the side boosters compared to the central core booster.
The central core was stated to be a standard F9.1 stack in every way.

This begs the question how many F9H vs F9 missions?

I suspect quite a few more F9s.

My cost reduction strategy would be to reuse "a many times used" F9 for the central core as an expendable on the F9H and just recover the side rockets. 

In the same discussion it was mentioned the Boca Chica is not intended for human flight.    That means you don't need to worry about abort landing sites for the Dragons.



Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 08/28/2014 08:34 pm
From the fiso mp3 it is obvious that the plumbing is different on the side boosters compared to the central core booster.
The central core was stated to be a standard F9.1 stack in every way.


The fiso mp3 showed clearly that Reissman knows very little about Falcon Heavy. He stated that the sidecores are the same as the central core and that is clearly not true. I don't see any reason why the plumbing of the side cores would be different as long as there is no crossfeed. And when there is crossfeed the plumbing of the central core needs to change too.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mvpel on 08/28/2014 09:13 pm
E-gad. If the FAA had been around in the early 1900's, airliners wouldn't be allowed to fly over cities at 37,000 feet, I suspect.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Coastal Ron on 08/28/2014 09:37 pm
From the fiso mp3 it is obvious that the plumbing is different on the side boosters compared to the central core booster.
The central core was stated to be a standard F9.1 stack in every way.


The fiso mp3 showed clearly that Reissman knows very little about Falcon Heavy.

Since your knowledge (and all of ours) lacks any real facts to determine whether what Reissman said is true or not, it would be premature to make that assessment.

Plus, he may have been generalizing for the audience.  For instance, the boosters have the same engines as the core, and the boosters have the same design and use the same tooling as the core.  So from a design standpoint they may in fact be 99% common from a functional standpoint, with the main difference being the attachment points.

Quote
He stated that the sidecores are the same as the central core and that is clearly not true.

Where do you get your facts from? Artist concepts?  But again, he could be generalizing.

Quote
I don't see any reason why the plumbing of the side cores would be different as long as there is no crossfeed. And when there is crossfeed the plumbing of the central core needs to change too.

Even with cross-feed they could run the plumbing through an insert at the bottom of the core where the plumbing already terminates at the engines.  That would simplify their plumbing off the LOX and RP-1 tanks.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 08/28/2014 09:44 pm

He stated that the sidecores are the same as the central core and that is clearly not true.

Where do you get your facts from? Artist concepts?  But again, he could be generalizing.


They are longer than the core
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sdsds on 08/28/2014 09:46 pm
That would be a *massive* sideways divert, that would take the IIP across many shipping lanes and flight corridors.

Do you have calculations for the size of the propulsion required? Is the sideways portion larger than the retrograde portion? As regards what's under the IIP trace, that's certainly related to calculating expected casualties, but the criteria for that is the same and a nearly empty all-liquid propellant stage at altitude doesn't seem to present an insurmountable safety risk to people aboard ships below....
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 08/28/2014 10:18 pm

He stated that the sidecores are the same as the central core and that is clearly not true.

Where do you get your facts from? Artist concepts?  But again, he could be generalizing.

They are longer than the core
Jim, would the FH main core be substantially different from the F9 core? In other words, not interchangeable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Coastal Ron on 08/28/2014 10:43 pm

He stated that the sidecores are the same as the central core and that is clearly not true.

Where do you get your facts from? Artist concepts?  But again, he could be generalizing.


They are longer than the core

Which is not really the point - if that were true (and you presented no more proof than guckyfan), does that mean that Reisman was generalizing or ignorant of the facts?

I think he was generalizing...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 08/29/2014 12:17 am

Which is not really the point - if that were true (and you presented no more proof than guckyfan).

It been shown/proven many times on this site.  And it is plainly obvious in the Spacex diagrams.

http://www.spacex.com/falcon-heavy
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dglow on 08/29/2014 01:04 am
Which is not really the point - if that were true (and you presented no more proof than guckyfan), does that mean that Reisman was generalizing or ignorant of the facts?

I think he was generalizing...

Reisman was bombarded with FH questions, yet attempted to field them as best he could, sometimes drifting into (educated) speculation. Every time he politely pointed out that others would know better, and the he could only authoritatively answer questions re: Commercial Crew and Dragon.

Did you listen to it yourself? If not, give guckyfan the benefit of the doubt.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mvpel on 08/29/2014 01:41 am

Which is not really the point - if that were true (and you presented no more proof than guckyfan).

It been shown/proven many times on this site.  And it is plainly obvious in the Spacex diagrams.

http://www.spacex.com/falcon-heavy

On what basis do you conclude that the "added length" shown in that diagram is not simply the same hollow interstage in which the bell of the upper stage Merlin nestles on the central core, as opposed to being an entirely different structure with different tanks?

Here's a little something I found from nearly two years ago:

That certainly is one difference to the reusable F9. I distinctly remember Musk saying that the interstage will be part of the first stage in the reusable version.

There's a gob of photos at that quote's link. There's also this photo, with the second stage at the left and the interstage on the right.

(http://www.spacex.com/files/assets/img/121408-2ndstageinterstage.jpg)

Repeat after me: the side cores are the same as the central core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 08/29/2014 01:49 am

On what basis do you conclude that the "added length" shown in that diagram is not simply the same hollow interstage in which the bell of the upper stage Merlin nestles on the central core, as opposed to being an entirely different structure with different tanks?


Because it is obvious it isn't.  The core stage and interstage is shorter than the extended booster and nose cone and the nose cone interface is at a point that is shorter than the core stage and interstage

edited



Repeat after me: the side cores are the same as the central core.

Wrong, quite the opposite, like I said,.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dglow on 08/29/2014 02:00 am

On what basis do you conclude that the "added length" shown in that diagram is not simply the same hollow interstage in which the bell of the upper stage Merlin nestles on the central core, as opposed to being an entirely different structure with different tanks?


Because it is obvious it isn't.  The core stage and interstage is longer than the extended booster and nose cone



Repeat after me: the side cores are the same as the central core.

Wrong, quite the opposite, like I said,.

I second Jim.

This isn't authoritative, but here are two casual references to stretched booster tanks: one earlier in this very thread (http://forum.nasaspaceflight.com/index.php?topic=32528.msg1136577#msg1136577), and another in Historical Spaceflight (http://forum.nasaspaceflight.com/index.php?topic=26667.msg1036516#msg1036516).

(my kingdom for a better search)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mvpel on 08/29/2014 02:10 am
Wrong, quite the opposite, like I said,.

And if I could bring myself to believe it, it would be utterly astounding to me that they would abandon what seem to me to be considerable benefits of identicality. Looking forward to the first FH launch, regardless.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Vultur on 08/29/2014 02:30 am
E-gad. If the FAA had been around in the early 1900's, airliners wouldn't be allowed to fly over cities at 37,000 feet, I suspect.

It is a problem for industries getting started today, yeah.

It always struck me as pretty implausible that a rocket accident would hit a ship or boat given how small they are.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dglow on 08/29/2014 02:37 am
Wrong, quite the opposite, like I said,.

And if I could bring myself to believe it, it would be utterly astounding to me that they would abandon what seem to me to be considerable benefits of identicality. Looking forward to the first FH launch, regardless.

1. Commonality isn't a binary thing. There are still benefits.
2. Increased performance, from larger tanks, is a benefit too.
3. Consider crossfeed: the boosters and core can't be identical.   
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars_J on 08/29/2014 03:29 am
Jim is right... Multiple images from SpaceX shows that the boosters are taller than the core. This is needed to get the full 53mT-to-LEO performance with cross-feed.

Image 1: Diagram of FH at the VAFB pad. Note that the diagram shows the RP1/LOX tank divide.

Image 2: The SpaceX website FH image. Note again the shifted RP1/LOX tank divide.

Image 3: Part of a NASA mural at the KSC vistor center. Again look carefully at the relative tank locations. Even here the RP1/LOX tank divide is indicated on the image.

Three separate renderings, all from SpaceX. All showing the same thing. Could SpaceX change their mind? Anything is possible. But the weight of evidence is substantial.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: QuantumG on 08/29/2014 03:32 am
Crazy idea.. perhaps SpaceX intends to fly an intermediate configuration first?

They did say they initially wouldn't have crossfeed, right?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: RonM on 08/29/2014 03:59 am
With crossfeed, the boosters will be longer than the core. Obviously, they are different from the core.

In FHs without crossfeed, even if the boosters have the same size tanks as the core, they will be different. The core has an interstage connecting to the second stage and two sets of mounts to attach two boosters. Each booster will have a nosecone and only one set of mounts to attach to the core.

The boosters will be similar to the core, but they will not be interchangeable. Nor will any FH core or booster be interchangeable with a F9.

That said, the vast majority of the parts for these stages will same.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 08/29/2014 04:02 am
Crazy idea.. perhaps SpaceX intends to fly an intermediate configuration first?

They did say they initially wouldn't have crossfeed, right?
That's plausible to me, though I still doubt it.

But anyway, the 53mT definitely needs stretched tanks. Another thing: we know the side boosters aren't identical since Elon said they get record mass fraction (but didn't say the same for the F9 core). That fits perfectly with stretched tanks (since stretched tanks would have proportionally less dry mass from the 9 M1Ds, etc). Everyone who does a naive simulation balks at the 50+mT estimate, usually because they don't include the stretched side boosters (among other things).

Another hint is that without stretching the side boosters, FH would have a much greater T/W ratio than Falcon 9 unless the second stage was stretched 3 times it's current length (which it won't). It'd be much more optimal to stretch the tanks and take advantage of the extra thrust.

And some people have even seen the FH hardware.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: LouScheffer on 08/29/2014 02:11 pm

It always struck me as pretty implausible that a rocket accident would hit a ship or boat given how small they are.
Yeah, but remember that submarine that was doing an emergency surface to show off for a guest, and whacked a fishing boat?  Given the size of the ocean, and small number of submarines, and how seldom they surface rapidly, I'd have given zillion to one odds against that.  (Unless, of course, the captain said "Watch this!  We'll scare the **** out of that boat up there!".  But no such comment was in the accident report...)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: AJW on 08/30/2014 05:34 am
Crazy idea.. perhaps SpaceX intends to fly an intermediate configuration first?

They did say they initially wouldn't have crossfeed, right?

My gut feel is that there will be no need to rush out an intermediate ship.  AF won't want one configuration for the demo next year and a different config for STP-2 or future flights.  The lesson from F9 to V1.1 is that if the final goal is certification, launching intermediate ships won't count.  Heavies will require 3 times the manufacturing time, so until the F9 cadence is up, a single FH test launch would cost SpaceX 3 F9 paying launches.   The cost savings of reusability for a FH launch is also 2-3 times greater, so I expect no rush until reusability is working.    SpaceX currently has customers for every V1.1 coming off the line, so until they are ahead of that curve, or they are up against the planned FH demo flight, no FH or variations.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: SpunkyEnigma on 08/30/2014 06:58 am
I've seen the mass numbers to GTO, but what kind of mass could a FH or FH-R get to EML2?  Assume 2nd stage is discarded after TLaI (Trans Lagrangian Injection, is there a better term??).  Payload would handle course correction and fine maneuvering to place into EML2 halo orbit.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: meekGee on 08/30/2014 04:16 pm

It always struck me as pretty implausible that a rocket accident would hit a ship or boat given how small they are.
Yeah, but remember that submarine that was doing an emergency surface to show off for a guest, and whacked a fishing boat?  Given the size of the ocean, and small number of submarines, and how seldom they surface rapidly, I'd have given zillion to one odds against that.  (Unless, of course, the captain said "Watch this!  We'll scare the **** out of that boat up there!".  But no such comment was in the accident report...)

The odds are mathematical.
Whether they were trying to scare them is a matter for speculation.

But the nice things about odds is that they remain the same irrespective of the history of actual occurrences.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sdsds on 08/30/2014 04:23 pm
what kind of mass could a FH or FH-R get to EML2?

My guesses: if a potential customer approached SpaceX with a need to send 17 t through TLI, SpaceX would try to sell that customer a flight on FH; if the customer needed 20 t through TLI, SpaceX wouldn't attempt the sale. That said, a wise customer wouldn't develop a TLI payload for FH greater than 15 t. ;)

(The difference between delta-v required for TLI and injection into an EML2-bound trajectory is small enough to ignore.)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 08/31/2014 06:50 am
For my understanding of Falcon 9 and Falcon Heavy.

The side cores of the FH are different in length so definitely not interchangeable with the central core or Falcon 9.

The central core of FH and Falcon 9 first stage are the same size but differ in attachment points, probably some wiring and capacity of load bearing. FH core needs to bear a higher payload weight. So they are also not interchangeable.

But a FH central core should be able to fly as a standalone Falcon 9. The idea being that the core flies first as a Falcon 9  and can then be used as an expendable FH core. Is that an option or am I off with the thought? Of course, if there will be plenty of FH flights with three reusable cores this may not be necessary.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sugmullun on 09/01/2014 02:47 am
I would be very interested in knowing instead of speculating, so if anyone...
I wouldn't think the boosters and central cores of FH would be all that similar aside from "framework".
I also would speculate that you take two random F9s after leaving the factory, that odds are one couldn't
interchange different booked payloads, even apart from those systems within a few feet of the payload.
With knowing the specs of a satellite(s) ahead of time and the performance effects of small changes I'd
think the F9s coming off the line would like Clydesdales and Thoroughbreds, same specie but not interchangable.
To get the most per dollar until SpaceX has a stable of different vehicles and reusable, I'd think that they'd be
making whatever practical change necessary to get the most from the core. Be it loft, value, mult-tasking...
I've never really got my head around "integration" but this would seem one definition?

Edit: this is over simplifying even for me, but no one would want to read me trying to be concise and detailed.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lar on 09/01/2014 03:17 am
I don't buy that. It is in SpaceX's best interest to have as few different core types as possible. Either 3 (single stick, booster and central) or just 2. I'm rather taken with the notion that a single stick and a center might be the same for manufacturing/operational efficiency reasons. Guckyfan might be on to something.

It seems obvious that you would want to make the interfaces such that there weren't two different side core types. I would see some sort of androgynous/symmetric arrangement of all the connectors so there wasn't a handedness.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sugmullun on 09/01/2014 04:06 am
I agree totally with you, that's the goal, but in the mean time SpaceX wants to sell launches with expendable and reliable rockets, that will do multiple missions sometimes.
Musk has in the past insisted on specs, which would not be needed for years, that drove his engineers to distraction
(according to what I've read). That supports your point.
But I'm asking if in the short term for the sake of business success, that they're not building the finished product yetgetting different needs and that there can be and need to be differences.
Edit to clarify: While up to some point (95% completed) all cores are identical, then because they know that they can make a change to improve some performance point...a change, which can't just be swapped out if they change their minds.
All speculation, as I said above...I'd like to know what the facts are.

Edit: grasping at a straw...
The F9R DEV 1 was different, beyond just fewer motors for the sake (maybe) of saving cost?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lar on 09/01/2014 04:22 am
Well since they have not yet flown have the central core with the cross feed and attachment points, clearly the single stick (no attachment points) has to live on for a while... to your point, it has to be a fair few launches from now.

And it will be a new rocket for AF certification reasons so they may well never. They don't want to have to certify F9R again.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/01/2014 01:25 pm

I also would speculate that you take two random F9s after leaving the factory, that odds are one couldn't
interchange different booked payloads,

There isn't any unique aspects that would prevent that.    Atlas uses the same booster configuration for all missions. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jcc on 09/01/2014 02:05 pm

I also would speculate that you take two random F9s after leaving the factory, that odds are one couldn't
interchange different booked payloads,

There isn't any unique aspects that would prevent that.    Atlas uses the same booster configuration for all missions.

My guess is the biggest reason not to interchange boosters is because most of the commercial payloads they are launching in the near term are delayed to the point of causing economic impact to the customer, so if a customer was promised a certain booster, they would not take lightly the idea of having their booster go to another customer, resulting in more delay to their flight.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/01/2014 02:14 pm

My guess is the biggest reason not to interchange boosters is because most of the commercial payloads they are launching in the near term are delayed to the point of causing economic impact to the customer, so if a customer was promised a certain booster, they would not take lightly the idea of having their booster go to another customer, resulting in more delay to their flight.

My point is that there is no difference in which vehicle they get. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 09/01/2014 04:26 pm

My guess is the biggest reason not to interchange boosters is because most of the commercial payloads they are launching in the near term are delayed to the point of causing economic impact to the customer, so if a customer was promised a certain booster, they would not take lightly the idea of having their booster go to another customer, resulting in more delay to their flight.

My point is that there is no difference in which vehicle they get.
But for Crew or nuclear cargo is there extra paper trail/process required?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mvpel on 09/02/2014 03:19 am
It seems obvious that you would want to make the interfaces such that there weren't two different side core types. I would see some sort of androgynous/symmetric arrangement of all the connectors so there wasn't a handedness.

You could make it so that all three cores were the same, with each one having both a crossfeed inlet and a crossfeed outlet on both sides, and the role of each core - left, right, or center - could be governed by valves and software.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lar on 09/02/2014 03:25 am
It seems obvious that you would want to make the interfaces such that there weren't two different side core types. I would see some sort of androgynous/symmetric arrangement of all the connectors so there wasn't a handedness.

You could make it so that all three cores were the same, with each one having both a crossfeed inlet and a crossfeed outlet on both sides, and the role of each core - left, right, or center - could be governed by valves and software.

Except I think we seem to be fairly firm about the side cores being a different height.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: beancounter on 09/02/2014 04:00 am
It seems obvious that you would want to make the interfaces such that there weren't two different side core types. I would see some sort of androgynous/symmetric arrangement of all the connectors so there wasn't a handedness.

You could make it so that all three cores were the same, with each one having both a crossfeed inlet and a crossfeed outlet on both sides, and the role of each core - left, right, or center - could be governed by valves and software.

Except I think we seem to be fairly firm about the side cores being a different height.
Well according to Garrett Reisman in his recent presentation, all 3 cores on the FH are identical except for some plumbing in order to take advantage of manufacturing simplicity and using the same bits and pieces on the cores.  He did qualify that a bit by saying that he wasn't fully across FH however he came across as fairly certain.  Same upper stage as well.
After all the speculation, go figure.
Cheers.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Misha Vargas on 09/02/2014 07:23 am
Except I think we seem to be fairly firm about the side cores being a different height.
Well according to Garrett Reisman in his recent presentation, all 3 cores on the FH are identical except for some plumbing in order to take advantage of manufacturing simplicity and using the same bits and pieces on the cores.  He did qualify that a bit by saying that he wasn't fully across FH however he came across as fairly certain.  Same upper stage as well.
After all the speculation, go figure.
Cheers.

I didn't hear that. I heard him say that they were going to make them with as much commonality as possible, which is not the same. Notice neither of us quotes him. I'll do it now!

Quote from: FISO Teleconference
Marshall Space Flight Center Dude: "Is the central core element there the same as the first stage on the Falcon 9?"

Garrett Reisman: "Yes."

MSFCD: "Same diameter?"

GR: "Same diameter, same propellent loads, same engines, yeah in fact, you know, when we build a core, there's no difference when it goes down the assembly line if it's destined to be a Falcon 9 or a Falcon Heavy."

MSFCD: "Ok, great how about the two outboard booster, are they the same as the central core?"

GR: "Yes the plumbing is slightly different, but . . . at least, it was in the original version of our design, I have to be honest with you, I haven't been keeping up with it, so I'm not sure if that's changed or not."

MSFCD: "But the plan [is] to have the propellent load and the same nine engines on the outboard boosters as the central core?"

GR: "Yeah, I think its yeah, same 9 engines, same structures so I think it's fair to say that our intention is to produce a single core and whether it's a outboard, or a central core, or a single stick for a Falcon 9, that it's as close as possible to being exactly the same configuration."

So he thinks it's their intention to make it as close as possible to identical. How close it can possibly be made is the question.

Besides that section, he stresses over and over that he doesn't work on heavy and hasn't been checking in on it since quite a while ago.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 09/02/2014 07:34 am
@Misha Vargas

Thanks for the transcript. It makes abundantly clear that he is not well informed on Falcon Heavy. Remember that everything about FH was not part of his presentation but part of the Q&A. Add the pictures on SpaceX homepage and all the calculations that don't show the performance claimed unless the booster tanks are stretched. IMO there can be no doubt that there are differences, just no difference in tooling required which is pretty much most of the needed communality between the different versions.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: QuantumG on 09/02/2014 07:59 am
The difference between a stretched tank on a side booster and the regular tank on a F9 or a central core of a FH, or for that matter, the second stage, is probably just the number of sections welded together. I guess that's what he meant.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mvpel on 09/05/2014 12:31 am
Having read Dmitry's writings on occasion I suppose it just surprises me that it could possibly be that simple.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Kabloona on 09/05/2014 02:26 am
Having read Dmitry's writings on occasion I suppose it just surprises me that it could possibly be that simple.

Common core for both F9 and FH, with stretched cores as FH boosters.

It's as simple as possible, but not simpler.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/11/2014 04:42 am
Key to further pricing reduction will be 2nd stage recovery which the F9R will enable.  That's going to be fun to see develop.
If they got 2nd stage recovery working, I wonder if it would make sense to go to a Falcon Doubly-Heavy.  Three reusable booster cores, three reusable upper stages.  The booster cores would all separate together, and come back from the same height sand speed.  The upper stages would all go to orbit, but only the middle one would go all the way to GTO.

They could probably still do 7+ tons to GTO that way, without expending any hardware, without a barge landing, and without using anything too novel, like a propellant depot or refuelable LEO/GEO shuttle.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: hkultala on 09/11/2014 05:24 am
Key to further pricing reduction will be 2nd stage recovery which the F9R will enable.  That's going to be fun to see develop.
If they got 2nd stage recovery working, I wonder if it would make sense to go to a Falcon Doubly-Heavy.  Three reusable booster cores, three reusable upper stages.  The booster cores would all separate together, and come back from the same height sand speed.  The upper stages would all go to orbit, but only the middle one would go all the way to GTO.

No, this would not make any sense at all.
The staging would be terribly difficult, and would make everything much riskier, with very little bonus.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: aero on 09/11/2014 05:39 am
Key to further pricing reduction will be 2nd stage recovery which the F9R will enable.  That's going to be fun to see develop.
If they got 2nd stage recovery working, I wonder if it would make sense to go to a Falcon Doubly-Heavy.  Three reusable booster cores, three reusable upper stages.  The booster cores would all separate together, and come back from the same height sand speed.  The upper stages would all go to orbit, but only the middle one would go all the way to GTO.

No, this would not make any sense at all.
The staging would be terribly difficult, and would make everything much riskier, with very little bonus.


I thought we had agreed that the boosters carry more prop to make up for the lack of the S2 mass. You can't add the S2 and the extra prop mass both and without the extra prop in the boosters, each with a second stage, all you get is an F9. Three F9's strapped together gives you 3 separate F9 payloads. No benefit at all, IMO.

Now, a more energetic S2 on the FH, that could help a lot since you're redesigning the FH anyway. Maybe SpaceX could buy a high energy stage 2 to avoid the development costs?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/11/2014 06:32 am
The staging would be terribly difficult, and would make everything much riskier, with very little bonus.
Are you thinking that I meant they'd still separate the side boosters first?

I meant that the upper-stage trio separates together from the booster-trio.  It would be the same as staging a Falcon 9, aside from having to trigger the staging hardware simultaneously.  It might take a little work, but I don't think this would be especially challenging.

The bonus is that you can still do roughly a Falcon Heavy size payload without sending the central core higher and farther downrange than a regular Falcon 9 booster, which means you don't have to expend it or do ocean recovery.

Without reusability, there is no point.  With flyback boosters, you're spending two additional expendable upper stages to save the central booster, which is a dubious bargain.  But if both upper and lower stages are reusable, this could be a straightforward way to satisfy the commercial market with full reusability.

I thought we had agreed that the boosters carry more prop to make up for the lack of the S2 mass. You can't add the S2 and the extra prop mass both and without the extra prop in the boosters, each with a second stage, all you get is an F9. Three F9's strapped together gives you 3 separate F9 payloads. No benefit at all, IMO.
First of all, getting triple the F9 payload would be nothing to sneeze at.  They probably can't do that with the Falcon Heavy without expending the central booster.  Notice on SpaceX's pricing page, they limit the Falcon Heavy payload to only ~40% more than the Falcon 9 payload.  They claim they can do 4 times as much as an F9, but they don't advertise a price for that.  40% more is probably about as much as they can do with the Heavy, if they want to do a conventional flyback of the central core.

But you would get additional payload compared to three Falcon 9s by throttling/shutting off the central upper core on the way to LEO, or by doing propellant transfer from the sides to the center after they reach LEO (might be easier than crossfeeding while the rockets are burning), before the GTO insertion or earth departure burn.

It's the same way the Falcon Heavy works on the lower stage: when the side boosters separate, the central core still has fuel (either from crossfeed or because they throttle it down and let the side-boosters do the work), so it's similar to a three-stage rocket.  You're saving energy for the payload by pushing less vehicle mass.

Do the same on the upper stage, and you get similar benefits.  Three separate Falcon 9 launches would take 2 more empty upper stages, an additional ~9 non-payload tons all the way to GTO (more, if they're reusable uppers).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: CuddlyRocket on 09/11/2014 08:57 am
Key to further pricing reduction will be 2nd stage recovery which the F9R will enable.  That's going to be fun to see develop.
If they got 2nd stage recovery working, I wonder if it would make sense to go to a Falcon Doubly-Heavy.  Three reusable booster cores, three reusable upper stages.  The booster cores would all separate together, and come back from the same height sand speed.  The upper stages would all go to orbit, but only the middle one would go all the way to GTO.

They could probably still do 7+ tons to GTO that way, without expending any hardware, without a barge landing, and without using anything too novel, like a propellant depot or refuelable LEO/GEO shuttle.

I suspect a single-core reusable BFR would actually be cheaper.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/11/2014 03:41 pm
I suspect a single-core reusable BFR would actually be cheaper.
I wouldn't be surprised.  I think the BFR is meant to have a very low marginal cost per flight.  But they might end up having reusable F9 upper stages (and flyback boosters) for five or ten years before the BFR.  The reusable upper stage might appear pretty quickly, once the flyback booster and Dragon 2 propulsive landing are working.

Assuming a 50% performance penalty for upper stage reuse, on top of Falcon Heavy only doing 40% more than the Falcon 9 with conventional flyback of the center core, a fully-reusable Falcon Heavy would only do 70% of a Falcon 9 with an expendable upper stage.  That doesn't put servicing the comsat market with fully reusable launch vehicles within their reach, despite the monstrous capacity of the Falcon Heavy as an ELV.

Maybe the downrange landing of the center core is the right answer.  But downrange landing is the theoretically easy answer to all of the problems with flyback boosters, yet they're still aiming for return to launch site.

It seems like they have to do something to get a bigger upper stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Space Ghost 1962 on 09/11/2014 05:28 pm
It seems like they have to do something to get a bigger upper stage.
Why?

If its a LEO destination, they get max capacity already to orbit with what they have.

If its beyond LEO, they first orbit a long life in space stage based on the second stage into a parking orbit. Then the 50T payload, rendezvous with the 50T in space stage. Since both launches rely on reusable launch systems that are reliable, the costs are quite low.

Have not idea if they could bring such off as feasible.

The point I am making is this is how you think of reusable launch systems in an economic footprint. You might stretch stages, you might tweak  vacuum iSP and other minor things. But otherwise 98% more of the same stuff.

So you never build a custom, high energy stage for FH/F9 - works against your architecture.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 09/11/2014 06:06 pm
It seems like they have to do something to get a bigger upper stage.
Why?

If its a LEO destination, they get max capacity already to orbit with what they have.

If its beyond LEO, they first orbit a long life in space stage based on the second stage into a parking orbit. Then the 50T payload, rendezvous with the 50T in space stage. Since both launches rely on reusable launch systems that are reliable, the costs are quite low.

Have not idea if they could bring such off as feasible.

The point I am making is this is how you think of reusable launch systems in an economic footprint. You might stretch stages, you might tweak  vacuum iSP and other minor things. But otherwise 98% more of the same stuff.

So you never build a custom, high energy stage for FH/F9 - works against your architecture.

If ever a F9, FH or BFR or mini BFR 2nd stage is reusable what you suggest Space Ghost makes perfect sense, alternately, you could make a stretch 2nd stage for the FH (they stretched the 1st and 2nd stages a little in the F9 1.1).

The drawbacks of the "space stage" is that it needs a new engine that saves weight against the Merlin 1D Vacuum (you just don't need that much thrust) and still has the 340+ Isp => an initial TWR of .25 or less would be acceptable but still 5 times what the old Kestrel did and the Kestrel didn't have the ISP that the Merlin 1D Vac has. Still saving weight would make a major difference on this stage and it's usefulness. I am convinced that SpaceX has the technology to handle orbital rendezvous and mating though.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Space Ghost 1962 on 09/11/2014 06:44 pm
It seems like they have to do something to get a bigger upper stage.
Why?

If its a LEO destination, they get max capacity already to orbit with what they have.

If its beyond LEO, they first orbit a long life in space stage based on the second stage into a parking orbit. Then the 50T payload, rendezvous with the 50T in space stage. Since both launches rely on reusable launch systems that are reliable, the costs are quite low.

Have not idea if they could bring such off as feasible.

The point I am making is this is how you think of reusable launch systems in an economic footprint. You might stretch stages, you might tweak  vacuum iSP and other minor things. But otherwise 98% more of the same stuff.

So you never build a custom, high energy stage for FH/F9 - works against your architecture.
The drawbacks of the "space stage" is that it needs a new engine that saves weight against the Merlin 1D Vacuum (you just don't need that much thrust) and still has the 340+ Isp => an initial TWR of .25 or less would be acceptable but still 5 times what the old Kestrel did and the Kestrel didn't have the ISP that the Merlin 1D Vac has. Still saving weight would make a major difference on this stage and it's usefulness. I am convinced that SpaceX has the technology to handle orbital rendezvous and mating though.
US iSP is the key concern. What I meant by "tweaking"

What would not surprise me:
  * Larger expansion nozzle (how?) with longer interstage (carbon composite?)
  * Altered injector :)
  * Different flow rate / thermal model allowing longer burns at lower thrust (milling / programming changes in engine controller)
  * Different MLI usage
  * Different power source (like with trunk)
  * Altered thrust structure
  * Scope of changes that fit within the envelope of existing qualification/GSE/flight test/flight operations

You can do more with a kerolox US for an in space stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/11/2014 07:29 pm
It seems like they have to do something to get a bigger upper stage.
Why?
The basic design of the Falcon Heavy depends on driving the center core farther and higher than the side boosters.  This means no return to launch site, unless they sacrifice most of the performance for it.  To combine high performance with flyback, they need to use the extra thrust and impulse to push a bigger upper stage, rather than to push the center core to a higher speed before staging.

It seems to be a design that's fundamentally unsuited to flyback of all three cores, without an increase in upper stage mass.

Quote
If its a LEO destination, they get max capacity already to orbit with what they have.
With return to launch site, they only get a modest increase of capacity over the single-core Falcon 9.  It would be unsatisfactory for a reusable upper stage to further reduce payload.

They only give a price for GTO launches, up to 6.4 tons.  Their claimed capacities above that, including the LEO payload figures, are almost certainly based on both using crossfeed and expending the center core (or using downrange recovery).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Space Ghost 1962 on 09/11/2014 08:53 pm
It seems like they have to do something to get a bigger upper stage.
Why?
The basic design of the Falcon Heavy depends on driving the center core farther and higher than the side boosters.
Nope.

Falcon 9/H fly lofted trajectories to keep the first stage/"zero stage" at a low enough speed to stage, to accommodate the economics of RTLS reuse.

Falcon H uses zero stage boosters which are stretched oversize F9 boosters to loft a mostly full core stage to significant altitude, whose reuse is still undefined but likely to be quite different, and more like a US reuse and not a F9 reuse.

We don't know the economics yet to make any judgements. It appears that on "non-legged" F9 launches since, they have been experimenting with lower cost reuse strategies, likely attempting to determine how little is necessary to get the stage down to sea level. With FH boosters, they likely will stage at a lower velocity as well, and have less penalties.

To me, with the discussion of landing on barges, this argues for a refinement of landing/braking economics. Some think that this indicates that they are having trouble already with acceptable economics. Others wonder if they have found a new "sweet spot" in the cost/performance curve, and they are attempting to stretch to capture a even better economic position. Such refinements would make sense in the early history of this kind of novel launch system capability - how much can you get out of it?

This means no return to launch site, unless they sacrifice most of the performance for it.
You may be presuming too much.

My guess is that they are using atmospheric drag/controls to reduce braking / steering props. As well as other means.

I think that the core will have a downrange landing. I know they talk of RTLS for the core now. So they'll change their mind - so what.


To combine high performance with flyback, they need to use the extra thrust and impulse to push a bigger upper stage, rather than to push the center core to a higher speed before staging.

No. Lofted trajectory for boosters, core flies a flatter trajectory, way beyond boost back economics. Second stage on LEO 50t finishes with insertion, and the overage from the core allows margin for second stage recovery.

It seems to be a design that's fundamentally unsuited to flyback of all three cores, without an increase in upper stage mass.
Yes. No.


Quote
If its a LEO destination, they get max capacity already to orbit with what they have.
With return to launch site, they only get a modest increase of capacity over the single-core Falcon 9.  It would be unsatisfactory for a reusable upper stage to further reduce payload.
That's why they won't do that for large (>8T) payloads.


They only give a price for GTO launches, up to 6.4 tons. 
Now you're confusing capability with business strategy.

First, tell me about the market for >6T sats. I'll clue you in - A: no market at this time. Why? Lack of advertised capacity.

When will this change? A: FH launches 6T sat. Then a new capacity from multiple providers will appear, and a few years later they'll be something that uses it. The market will be very different then in many ways.

Makes no sense to do otherwise.

Their claimed capacities above that, including the LEO payload figures, are almost certainly based on both using crossfeed and expending the center core (or using downrange recovery).
We have no idea their product/services strategy right now. Too presumptive to guess - perhaps they do cross feed from the start and under report.

My guess is that the point of the FH program is to first target 6T sats and get competitive on becoming a full services commercial provider. Then, to do national security launches that Delta IVH currently does, and on the third successful flight Delta IV is cancelled.

Some circus acts involving reusability as well. Actual, operational reusable operation will come on last, because it will need to be a comprehensive solution we have yet to see.

I think that everyone is fooled at the moment. They think its a F9 with legs and little else. I think the scope is much larger, and anyone that tries to catch up by shooting at what you see right now, will undershoot by a great deal.

This may be a much longer term program than it seems. It wouldn't surprise me if any rivals attempt it, they will encounter abrupt changes unexpected. Large capital overruns. If they were to try, I'd suggest a very agile launch vehicle design that could be altered to follow such surprises. Not one bit of "secret sauce" per se, but lots of them along a path. Scares the heck out of traditional aerospace engineers, who tend to be very conservative.

Fun to watch.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Wetmelon on 09/12/2014 01:35 am
Waz_Met_Jou did some detailed analysis and came up with these numbers for Falcon Heavy, which is very close to what Elon said - with crossfeed and core reuse, they get about 7 tonnes to GTO.  Note that the second and 4th rows are BOOSTER reuse, not center core.

http://i.imgur.com/gbBJcoV.png
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 09/12/2014 02:49 am
Waz_Met_Jou did some detailed analysis and came up with these numbers for Falcon Heavy, which is very close to what Elon said - with crossfeed and core reuse, they get about 7 tonnes to GTO.  Note that the second and 4th rows are BOOSTER reuse, not center core.

http://i.imgur.com/gbBJcoV.png

Great work. Row 4 is definitely an eye opener. 41t to LEO for basically an expendable F9.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: docmordrid on 09/12/2014 03:20 am
Waz_Met_Jou did some detailed analysis and came up with these numbers for Falcon Heavy, which is very close to what Elon said - with crossfeed and core reuse, they get about 7 tonnes to GTO.  Note that the second and 4th rows are BOOSTER reuse, not center core.

http://i.imgur.com/gbBJcoV.png

Great work. Row 4 is definitely an eye opener. 41t to LEO for basically an expendable F9.

Makes one wonder if that's to be the fate of at least some near-EOL re-used F9 cores,
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 09/12/2014 06:22 am
Re no advertised capacity for GTO of sats >6t.

Surely Ariane could offer this today, in place of dual manifesting?

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: SwissCheese on 09/12/2014 10:21 am
Waz_Met_Jou did some detailed analysis and came up with these numbers for Falcon Heavy, which is very close to what Elon said - with crossfeed and core reuse, they get about 7 tonnes to GTO.  Note that the second and 4th rows are BOOSTER reuse, not center core.

http://i.imgur.com/gbBJcoV.png

Is the last row with RTLS of the center core or with downrange landing? (I suspect RTLS)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 09/12/2014 12:12 pm
Very interesting calcuations. However what about the TMI figures? The SpaceX website gives 13 t to TMI. Ihat sheet gives only 10.1 tons.


So hopefully the 8.1 t with booster reuse are also on the low side. That would mean a Red Dragon can be sent to Mars with significant payload to the surface with booster reuse, basically loosing only a Falcon 9.


Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Space Ghost 1962 on 09/12/2014 03:33 pm
Re no advertised capacity for GTO of sats >6t.

Surely Ariane could offer this today, in place of dual manifesting?

Cheers, Martin
No one would fly such with one/few/limited provider. If the provider proved to be in some way the only one, and they go away for a few years, there's no ride.

Only when the capacity is larger across the board, such that you have a plan "B" / fallback / multiple choice/enough experience, are sat vendor / customers tempted.

Things you could do with 6+2T:
 +  Larger / greater antenna complex
 +  More elaborate beam forming / channelization
 +  Higher power
 +  Longer life
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: newpylong on 09/12/2014 11:31 pm
No, there simply is no requirement for that. Ariane 5 does nearly 10 tons to GTO and D-IVH does 13. There is existing capability if someone wanted to build that big.

Satellites are getting smaller with the onset of SEP, not larger.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 09/13/2014 09:15 am
Re no advertised capacity for GTO of sats >6t.

Surely Ariane could offer this today, in place of dual manifesting?

Cheers, Martin
No one would fly such with one/few/limited provider. If the provider proved to be in some way the only one, and they go away for a few years, there's no ride.

Only when the capacity is larger across the board, such that you have a plan "B" / fallback / multiple choice/enough experience, are sat vendor / customers tempted.

Things you could do with 6+2T:
 +  Larger / greater antenna complex
 +  More elaborate beam forming / channelization
 +  Higher power
 +  Longer life
Yeah, but your following sentence said that another provider would need to come onstream *after* FH in the higher payload class before anyone would use it.

Given that FH will provide the (reasonably priced) backup to Ariane, A6 is planning to reduce their capacity, rather than assuming someone will come along and want it. (Yes, I know A5ME will increase payload in the meantime.)

Cheers, Martin

PS I did try to quote your text in my original response, but Tapatalk didn't bring it across.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Space Ghost 1962 on 09/13/2014 11:07 pm
Re no advertised capacity for GTO of sats >6t. Surely Ariane could offer this today, in place of dual manifesting?
No one would fly such with one/few/limited provider. If the provider proved to be in some way the only one, and they go away for a few years, there's no ride.
Yeah, but your following sentence said that another provider would need to come onstream *after* FH in the higher payload class before anyone would use it.
The problems with saying too much in too little a format.

Ok, it's really complicated how growth occurs in commercial sats, both historically and at the moment with market thrash. And, it would seem that this is happening to institutional missions, as yesterday I heard back from the institutional side who complained that they couldn't get the provider(s) attention, which is weird because of the competitive race now to inflate manifests with new contracts. So when I mean changing, right now its ask me every week.

Newpylong is correct, there are no requirements for >6T. But back in the spinner days, there wasn't much >3T, until 4, 4.5T ones started getting mooted. And then Direct Broadcast Sats, and larger coverage one got us into the 6T range. So it goes.

By the way, SEP is as much a growth hold-off as well as an insurance policy of US fizzle (sub performance or "issue" on injection), as it is also in some cases a life extender.

You don't market what no one has a requirement for. However, to show leadership, you build in "headroom" in the form of additional capabilities / capacities / services. The additional capacities can be rationalized in various ways such as multiple launch or various kinds of secondary payloads. This is the case with Ariane 5 ECA. In a different way with EELV, aimed at a different customer.

There is an indeterminate wait before the market may exploit such. Years to decades. But in general you look for repeated capacity, like (as you point out) Ariane 5 has already lifted. You might say that the first likely 8T bird would likely fly on Ariane 5 for this reason, once Falcon/Delta IV/other proved it was routine on another launcher. This assumes that such launches (including all services) are competed for given on orbit expectations - they're not. Yet. This would be premium priced. Note that the commercial risk for such is much higher, and the insurance costs also aren't linearly scaled, among others. Hard to explain.

One of the hardest things to explain is the way by which capacity growth actually occurs. Clearly its been possible to increase capacity for a while with options, not ideal. Clearly risks overwhelm advantages. But with current market changes, this may change. Certainly FH will justify itself as a full up competition including 6T.

I gave prior post some teasers for what such vendors would likely desire to go for such. In a nutshell, more of everything with less risk, such that they don't need as many to do as much/more.  Concentrate on the "less risk". When is 8T less risk than 6T?  Well, it might start when they are about the same? When does this occur? When somebody gets away with it and scores an advantage ... like in the past.

Given that FH will provide the (reasonably priced) backup to Ariane, A6 is planning to reduce their capacity, rather than assuming someone will come along and want it. (Yes, I know A5ME will increase payload in the meantime.)
A6 planning is out of phase with the market IMHO. But, what IS the market at the moment? Is it an inflection? Is it chaos? Lots here.

I think you can't presume much here. No one will "forward price" commercial launch service capacity increase.

I think that dual 4/4.5T launch will happen first with FH, then 6T. Then with gradual erosion at the top end to A5 payloads and manifest switches, that's when capacity teases will start.

Long before a commercial 8T launches on either, FH will do a > 8T launch. That's when requirements may shift.

Attempting to answer your question.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 09/14/2014 02:16 pm
Attempting to answer your question.

Another great answer. It's very much appreciated.

Many thanks, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sdsds on 09/14/2014 08:12 pm
Trying to think out of the "box." Does the disruption in the marketplace caused by FH also extend to satellite manufacturers? Just as an example, could Orbital Sciences slap two GEOStar buses together and create a 6.5 t offering? It might not be maximally mass efficient, but if FH drives down launch costs for that payload mass low enough does that enable that kind of mass inefficiency by the satellite manufacturers?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: hypermecanix on 09/15/2014 04:37 pm
Terrestar-1 was a commercial payload (7 mT) single launched on A5 in 2009.
There is also the Alphabus platform, designed up to 8 mT.
Capacity exists but doesn't seem to attract operators. Whether it's because of the cost, or the lack of backup launch provider is the right question.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: pogo661 on 09/15/2014 05:27 pm
Do we know what the Crossfeed plumbing will look like?  I assumed that the center core would have the 3 starboard engines sucking fuel and oxider from the starboard booster.  Ditto for port.  And the center 3 engines were the only ones that could pull from the center core tanks.

Also that fuel and oxidizer hookups to the side boosters would be fairly big, high flow pipes,  without separate valves (beyond the individual engine valves) so that cross feed cores and boosters couldn't be easily repurposed for non-crossfeed service.

Are there other proposals out there?  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: oldAtlas_Eguy on 09/15/2014 06:02 pm
Do we know what the Crossfeed plumbing will look like?  I assumed that the center core would have the 3 starboard engines sucking fuel and oxider from the starboard booster.  Ditto for port.  And the center 3 engines were the only ones that could pull from the center core tanks.

Also that fuel and oxidizer hookups to the side boosters would be fairly big, high flow pipes,  without separate valves (beyond the individual engine valves) so that cross feed cores and boosters couldn't be easily repurposed for non-crossfeed service.

Are there other proposals out there?  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

A seperate pump would requires something like a larger size GG and turbo pump to pump the amounts we are talking about on each side.  So I do not think that is is a viable solution.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/15/2014 07:57 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is just additional feed lines and valves.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: IslandPlaya on 09/15/2014 08:56 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is just additional feed lines and valves.
The existing pumps need more flow-rate than they do in normal operation though.
Are all Merlin turbopumps designed with this extra capacity?
I would think not, but I don't know enough to say for sure.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: DanielW on 09/15/2014 09:01 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is "just" additional feed lines and valves.
The existing pumps need more flow-rate than they do in normal operation though.
Are all Merlin turbopumps designed with this extra capacity?
I would think not, but I don't know enough to say for sure.

I don't think this is correct. The pumps in question are on the center core. They don't know that they are pulling from the side tanks. As Jim said it is just more plumbing and valves. (the word just implying no changes to the turbopumps not a triviality of execution)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Herb Schaltegger on 09/15/2014 09:06 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is just additional feed lines and valves.
The existing pumps need more flow-rate than they do in normal operation though.
Are all Merlin turbopumps designed with this extra capacity?
I would think not, but I don't know enough to say for sure.

I don't think this is correct. The pumps in question are on the center core. They don't know that they are pulling from the side tanks. As Jim said it is just more plumbing and valves. (the word just implying no changes to the turbopumps not a triviality of execution)

What they "know" is that there is working fluid with certain characteristics (specifically inlet temperature and pressure) that fall within an expected range. The question is whether pumping that fluid through additional plumbing and fixtures from the boosters into the central core results in significantly-different than expected conditions as compared to pumbing that fluid from tanks in the central core itself. Or to put it another way, will the turbopumps have to be modified or not. This is still an open question as far as I know.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 09/15/2014 09:16 pm
Crossfeed seems simple until you start getting into the details. I hadn't thought about the fuel pump requirements.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/15/2014 09:18 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is just additional feed lines and valves.
The existing pumps need more flow-rate than they do in normal operation though.
Are all Merlin turbopumps designed with this extra capacity?
I would think not, but I don't know enough to say for sure.
I think you've got a misconception here.

There are essentially two stages of propellant feed, we could call them the push step and the pull step.  The push step is pressure/gravity feeding.  The tanks are pressurized with helium, and there is additional pressure because you're drawing from the bottom of each tank with all the weight of fuel or oxygen above, so if you simply hooked up a hose from the tank to the open air, it would spray out quite forcefully.  The pull step is the turbopump, which is part of each individual engine.  The main function of the turbopump is to provide high pressure for the combustion chamber.

With crossfeed, you basically have more outlets from the side booster tanks to some of the center core's engines.  The turbopumps don't have to work harder, but you do have to put helium into the side booster tanks faster, since they're emptying faster, so the pressurization system needs to be able to do that.  They could add another pump in the middle but it's an unnecessary complication, so they're probably not doing that.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Karloss12 on 09/15/2014 09:25 pm
With the F9 v1.0 tick-tack-toe arrangement, Elon indicated the centre core would fuel the 3 centre engines and the side cores would fuel 3 engines each (3-3-3).

Going to the Octaweb configuration would a 4-1-4 configuration be more optimum or would the side cores run out of fuel to early?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: 411rocket on 09/15/2014 09:53 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is "just" additional feed lines and valves.
The existing pumps need more flow-rate than they do in normal operation though.
Are all Merlin turbopumps designed with this extra capacity?
I would think not, but I don't know enough to say for sure.

I don't think this is correct. The pumps in question are on the center core. They don't know that they are pulling from the side tanks. As Jim said it is just more plumbing and valves. (the word just implying no changes to the turbopumps not a triviality of execution)

It is my understanding, that the turbopumps are part of each engine. The side boosters may require, larger piping for feeding the center core engines, as well as their own engines. This would be in addition, to valves & quick disconnects, interconnecting the side boosters & core similar to the launch pad connections for fuel & oxidizer.

Of course I could be wrong, but I'm thinking of it, as a remote fuel & oxidizer source, instead of initially using the internal tanks.

My analogy for it, would be running a Military AC power generator off a 45 Gallon drum of fuel Vs the built in fuel tank (which can be a pain to refill, if trailer mounted). Fuel source, is controlled by valve selection, remote drum or built in tank.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/15/2014 09:54 pm
With the F9 v1.0 tick-tack-toe arrangement, Elon indicated the centre core would fuel the 3 centre engines and the side cores would fuel 3 engines each (3-3-3).

Going to the Octaweb configuration would a 4-1-4 configuration be more optimum or would the side cores run out of fuel to early?
Setting aside the complex question of the best time to accept a reduction of thrust in order to reduce vehicle mass and drag, I suspect that the cross-fed engines will shut down during separation, leaving only the non-crossfed engines to provide control authority, and at least two are needed for strong roll-control.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: IslandPlaya on 09/15/2014 09:57 pm
  Could crossed be tank to tank with a separate pump,  so that the engine plumbing for crossfeed was the same as non crossfeed?

There are no additional pumps involved with cross feed, it is just additional feed lines and valves.
The existing pumps need more flow-rate than they do in normal operation though.
Are all Merlin turbopumps designed with this extra capacity?
I would think not, but I don't know enough to say for sure.
I think you've got a misconception here.

There are essentially two stages of propellant feed, we could call them the push step and the pull step.  The push step is pressure/gravity feeding.  The tanks are pressurized with helium, and there is additional pressure because you're drawing from the bottom of each tank with all the weight of fuel or oxygen above, so if you simply hooked up a hose from the tank to the open air, it would spray out quite forcefully.  The pull step is the turbopump, which is part of each individual engine.  The main function of the turbopump is to provide high pressure for the combustion chamber.

With crossfeed, you basically have more outlets from the side booster tanks to some of the center core's engines.  The turbopumps don't have to work harder, but you do have to put helium into the side booster tanks faster, since they're emptying faster, so the pressurization system needs to be able to do that.  They could add another pump in the middle but it's an unnecessary complication, so they're probably not doing that.
Thanks. I think I understand more clearly now.
It's not at all trivial though and that's why x-feed will come later than the FH debut, I guess.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Space Ghost 1962 on 09/15/2014 10:39 pm
Terrestar-1 was a commercial payload (7 mT) single launched on A5 in 2009.
Business failure. An example of "what not to do". And of not "getting away with" a big sat as a win.

There is also the Alphabus platform, designed up to 8 mT.
Capacity exists but doesn't seem to attract operators. Whether it's because of the cost, or the lack of backup launch provider is the right question.
It's not the bus that is the big deal, it's the solar and antenna array(s).

The temptation is to have one big sat to do 2-3 smaller sat's service footprint.

One bus. Multiple antenna cluster, feeds, and transponders. Large area solar that supplies enough even after 15 years in space degradation.

Ironically, the primary point of a big sat is to reduce, among other things, launch cost and launch risk. If launch risk stays the same (or worse), better to not have the big guys, because you risk less capacity loss. If your launch risk drops with increased launch cost, then go with big sat. If both launch costs and launch risks both go down, its life cycle costs of the entire constellation that matter, so you look for the "right size" by modelling factors - like small/large/dispersed geo coverage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/15/2014 11:56 pm

The existing pumps need more flow-rate than they do in normal operation though.


No, they don't, they are just drawing propellant from a different tank.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nomadd on 09/16/2014 12:16 am
Terrestar-1 was a commercial payload (7 mT) single launched on A5 in 2009.
Business failure. An example of "what not to do". And of not "getting away with" a big sat as a win.

Skyterra 1 was of similar size and also a huge failure. It has a 70' antenna with 500 spot beams and as far as I know, it's not doing much besides replacing an old MSAT bird. And it seems like SpaceX making launch prices even cheaper might ironically make the case for giant comms sats even weaker since it would make more frequent replacement with newer technology birds more attractive and hurt the case for satellites that cost $200 million to build and take 20 year lifespans to justify.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: S.Paulissen on 09/16/2014 03:45 am
Terrestar-1 was a commercial payload (7 mT) single launched on A5 in 2009.
Business failure. An example of "what not to do". And of not "getting away with" a big sat as a win.

Skyterra 1 was of similar size and also a huge failure. It has a 70' antenna with 500 spot beams and as far as I know, it's not doing much besides replacing an old MSAT bird. And it seems like SpaceX making launch prices even cheaper might ironically make the case for giant comms sats even weaker since it would make more frequent replacement with newer technology birds more attractive and hurt the case for satellites that cost $200 million to build and take 20 year lifespans to justify.

I don't think lifespan of satellite will be highly effected by launch prices.  I believe that's largely a function of the economics of delayed return on investment (takes longer to turn a true profit) coupled with technology advancement (new technology may make your bird obsolete before ROI has been achieved).   Add in the risk of loss with a single bigsat versus three sats and it becomes risk management to avoid a single launch.
 
Think of the risk statistics three dice rolls versus one.

Further, if launch costs are lowered by SpaceX as planned the cost for big payloads will be decreasing as well in the long run (potentially even more than regular sats if payloads are sufficiently high enough up the cost curve elbow).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: macpacheco on 09/16/2014 04:29 am
I don't think lifespan of satellite will be highly effected by launch prices.  I believe that's largely a function of the economics of delayed return on investment (takes longer to turn a true profit) coupled with technology advancement (new technology may make your bird obsolete before ROI has been achieved).   Add in the risk of loss with a single bigsat versus three sats and it becomes risk management to avoid a single launch.
 
Think of the risk statistics three dice rolls versus one.

Further, if launch costs are lowered by SpaceX as planned the cost for big payloads will be decreasing as well in the long run (potentially even more than regular sats if payloads are sufficiently high enough up the cost curve elbow).
The best investment a satellite operator can do today to reduce total cost of ownership for a given GEO mission is going full electric. Allows launching a 8ton bird with F9R class launcher, while still leaving an extra decade worth of station keeping xenon. The main drawback is having another decade to use the satellite might not make much sense, birds launched today will be utterly obsolete 30+ years from now.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 09/16/2014 08:24 am
With the F9 v1.0 tick-tack-toe arrangement, Elon indicated the centre core would fuel the 3 centre engines and the side cores would fuel 3 engines each (3-3-3).

Going to the Octaweb configuration would a 4-1-4 configuration be more optimum or would the side cores run out of fuel to early?
Setting aside the complex question of the best time to accept a reduction of thrust in order to reduce vehicle mass and drag, I suspect that the cross-fed engines will shut down during separation, leaving only the non-crossfed engines to provide control authority, and at least two are needed for strong roll-control.
No, it seems clear that the core will fly on nine engines after booster separation. Otherwise, gravity losses would be too high.

(I know this is past the point of major gravity losses, but this is essentially still a full F9 + F9US + payload, and 3x engines would cut T:W from "something over 1.2" to "something over 0.4".)

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 09/16/2014 09:30 am
Setting aside the complex question of the best time to accept a reduction of thrust in order to reduce vehicle mass and drag, I suspect that the cross-fed engines will shut down during separation, leaving only the non-crossfed engines to provide control authority, and at least two are needed for strong roll-control.
No, it seems clear that the core will fly on nine engines after booster separation. Otherwise, gravity losses would be too high.

(I know this is past the point of major gravity losses, but this is essentially still a full F9 + F9US + payload, and 3x engines would cut T:W from "something over 1.2" to "something over 0.4".)

Cheers, Martin

I think the question was for the moment of separation. Would the crossfeed engines shut down for separation and then restart? At least this was my understanding.

I agree with you that the engines will not shot down even temporarily. It would be easier and safer to keep them running IMO.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: gospacex on 09/16/2014 10:15 am
Sometime ago I thought that x-feed is to be implemented by pumping fuel/oxidizer from *tank to tank*, not *from tank to engines*, IOW: with additional pipes, and possibly with additional pumps.

This way, the complex piping at the bottom needs absolutely no changes compared to F9.

Why do you assume it won't be done this way?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 09/16/2014 11:34 am
Setting aside the complex question of the best time to accept a reduction of thrust in order to reduce vehicle mass and drag, I suspect that the cross-fed engines will shut down during separation, leaving only the non-crossfed engines to provide control authority, and at least two are needed for strong roll-control.
No, it seems clear that the core will fly on nine engines after booster separation. Otherwise, gravity losses would be too high.

(I know this is past the point of major gravity losses, but this is essentially still a full F9 + F9US + payload, and 3x engines would cut T:W from "something over 1.2" to "something over 0.4".)

Cheers, Martin

I think the question was for the moment of separation. Would the crossfeed engines shut down for separation and then restart? At least this was my understanding.

I agree with you that the engines will not shot down even temporarily. It would be easier and safer to keep them running IMO.

If I may speculate on the switchover mechanism.

This seems a tricky problem if the cutover from crossfeed to core feed has to be carefully co-ordinated. But what is the consequence if the core feed is slowly opened up until fully open, stable engine operation is confirmed, then the crossfeed is slowly closed down?

Booster will be nearly empty, while core has a nearly full prop load. Static pressure from the core feed will be higher, so the engine will see its inlet pressure rise. I'd think you'd want the core feed valve to open slowly, in order that this transition not be too severe. (I suspect you'd also want to coordinate switchover of RP-1 & lox to ease the job of the Merlins in maintaining mixture ratio.)

The crossfeed will now see a higher pressure from the core end than the booster end, so presumably there will be some reverse-direction flow during the changeover period. While this is not ideal, it's also not the end of the world, as long as the reverse flow doesn't screw up operation of the booster engines. The prop can still be burnt by the booster, either before BECO, or during recovery.

Perhaps the simplest mode of switchover would be to have a one-way valve in the crossfeed pipe, which will naturally shut the flow down as soon as it reverses direction. However, I suspect that an active valve that closes (slowly, to avoid waterhammer) at onset of backflow is the better solution. Note that this valve is mission critical. If it leaks after booster sep, then you're basically dumping prop overboard, so unlikely to reach the target orbit.

tl;dr the transition from crossfeed to core feed may not be quite so tricky to achieve as you'd otherwise think.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 09/16/2014 11:39 am
Sometime ago I thought that x-feed is to be implemented by pumping fuel/oxidizer from *tank to tank*, not *from tank to engines*, IOW: with additional pipes, and possibly with additional pumps.

This way, the complex piping at the bottom needs absolutely no changes compared to F9.

Why do you assume it won't be done this way?

Because prop is fed into the tanks from the bottom.

At BECO, with 27 engines firing and relatively high G's, the crossfeed would have to be pumped to a pretty high pressure to combat the static pressure of the full tank that you're pumping into.

Tanks are designed to abstract from the bottom, and feed into the engines. Tank-to-engine is just a bit-more complicated version of the mature systems that already achieve this on F9.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/16/2014 03:20 pm
Perhaps the simplest mode of switchover would be to have a one-way valve in the crossfeed pipe, which will naturally shut the flow down as soon as it reverses direction. However, I suspect that an active valve that closes (slowly, to avoid waterhammer) at onset of backflow is the better solution. Note that this valve is mission critical. If it leaks after booster sep, then you're basically dumping prop overboard, so unlikely to reach the target orbit.
The simplest mode of switchover is to shut off all of the engines fed from the side booster tanks, separate, and then restart the ones on the core (before restarting some on the side boosters for flyback).  It's not like these engines don't have restart capability, and (assuming a little performance margin for mission assurance) this gives you a few seconds to retry sticking valves before they cause a mission failure.

Opening a connection between the side booster tanks and the center core tank is opening a can of worms.

I wouldn't say they're definitely not doing it, but I don't see why they would.  The reduction in thrust for a few seconds during side-booster separation and engine restart is minor.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/16/2014 03:45 pm
there is no need to shutdown engine nor would they want to. 

That is the worst possible way of doing it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Roy_H on 09/16/2014 03:49 pm
Just to be clear. it makes no sense to pump from tank to tank. These fuel pumps are big and expensive, only 1 per engine. An additional pump to go from tank to tank would be a major waste of resources. The inlet to each of the 8 pumps for outboard engines must have two pairs of valves, one from main core, the other from side booster closest to that engine.

Edit "pairs of valves" as one for LOX and the other for RP1.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 09/16/2014 04:30 pm
Just to be clear. it makes no sense to pump from tank to tank. These fuel pumps are big and expensive, only 1 per engine. An additional pump to go from tank to tank would be a major waste of resources.
If they did put a fuel pump in for crossfeed, it wouldn't be a Merlin turbopump, but a much less powerful pump, with much lower output pressure.  The requirements of such a pump would be too different from the requirements of a pump for directly feeding the combustion chamber.

They could use one between the side booster and the engines it's crossfeeding as an alternative to one of the valves between the center tank and one side's crossfed engines, to keep the pressure higher from the booster feed line than the center tank feed.  I don't think they'd do it this way, though.

Quote
The inlet to each of the 8 pumps for outboard engines must have two pairs of valves, one from main core, the other from side booster closest to that engine.
There is not necessarily a set of valves for each engine.  There could just be a set of valves for each side-booster.

For each line between a side-booster and the center core, you need one valve on each side and a detachable coupling.  They might also have a system for purging the line in an orderly fashion before decoupling, or they might just let the contents spill when they open it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: oldAtlas_Eguy on 09/16/2014 04:34 pm
A little bit of history.  The old Atlas design 1957-1990 used a booster package that separated almost immediately after engine shutdown.  They actually just fell off sliding away on rails because the center engine was still going.  The shutdown valve was on the booster not the engine package.  So no prop was lost.

So a valve on the boosters shut down causing flow to stop from the booster to the engine.  Because flow stops (or reduces) the prop starts flowing from another valve hydraulically activated when the pressure in the feed from the booster goes below a certain amount.  No commands, no tricky computer software, just good mechanical engineering which will be more reliable.

Valves needed to accomplish:
1) Cutoff valve on booster
2) Hydraulically activated valve on center stage
3) Backflow valve on center stage
4) Engine cutoff valves on center stage (same as for no crossfeed)
5) Protection secondary cutoff valve on booster stage
6) Protection valve on center stage (secondary to backflow)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 09/16/2014 05:17 pm
A little bit of history.  The old Atlas design 1957-1990 used a booster package that separated almost immediately after engine shutdown.  They actually just fell off sliding away on rails because the center engine was still going.  The shutdown valve was on the booster not the engine package.  So no prop was lost.

So a valve on the boosters shut down causing flow to stop from the booster to the engine.  Because flow stops (or reduces) the prop starts flowing from another valve hydraulically activated when the pressure in the feed from the booster goes below a certain amount.  No commands, no tricky computer software, just good mechanical engineering which will be more reliable.

Valves needed to accomplish:
1) Cutoff valve on booster
2) Hydraulically activated valve on center stage
3) Backflow valve on center stage
4) Engine cutoff valves on center stage (same as for no crossfeed)
5) Protection secondary cutoff valve on booster stage
6) Protection valve on center stage (secondary to backflow)

Thanks for this post, good information.

I'm so interested in the crossfeed system and how it works that I'd work for free to do the testing and development. (If I could afford to do so).

The testing mockups, valves, flow tests, hot fires, separation, controls.  It's all very fascinating from a mechanical and integration perspective.  I consider it engineering bliss!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: RanulfC on 09/16/2014 09:09 pm
The simplest mode of switchover is to shut off all of the engines fed from the side booster tanks, separate, and then restart the ones on the core (before restarting some on the side boosters for flyback).  It's not like these engines don't have restart capability, and (assuming a little performance margin for mission assurance) this gives you a few seconds to retry sticking valves before they cause a mission failure.

"Restarts" in this case require loading "shots" of the highly toxic chemical they use to start the engines in the first place. Besides you NEVER want to shut down an engine in flight during a boost phase and then "hope" it restarts in flight. Once you start it you do NOT shut it off unless you have too. (Upper stages are NOT boosters and this doesn't apply to them)

Randy
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 09/17/2014 01:30 am
Perhaps the simplest mode of switchover would be to have a one-way valve in the crossfeed pipe, which will naturally shut the flow down as soon as it reverses direction. However, I suspect that an active valve that closes (slowly, to avoid waterhammer) at onset of backflow is the better solution. Note that this valve is mission critical. If it leaks after booster sep, then you're basically dumping prop overboard, so unlikely to reach the target orbit.
The simplest mode of switchover is to shut off all of the engines fed from the side booster tanks, separate, and then restart the ones on the core (before restarting some on the side boosters for flyback).  It's not like these engines don't have restart capability, and (assuming a little performance margin for mission assurance) this gives you a few seconds to retry sticking valves before they cause a mission failure.

Opening a connection between the side booster tanks and the center core tank is opening a can of worms.

I wouldn't say they're definitely not doing it, but I don't see why they would.  The reduction in thrust for a few seconds during side-booster separation and engine restart is minor.

A slow measured transition from:
0% core - 100% side booster to 100% core -0% booster with all three cores firing
Once cross feed flow is isolated then prep for separation
Then separate like a normal FH.

The sequence, timing and profile of the transition is the testing I refered to above.  It would be very exciting to see the system response and develop the sequence of operations and timing needed. 

But if you tested the system fully you can create that sequence and timing.

I think you can build a test rig that doesn't actually fire the engines but tests the plumbing with real flows. Just flow the LOx and RP1 as long as they have the same flow and pressure requirements.  Then you could do multiple runs a day and test the plop out of it for a relatively small sum. 

Then hit the test stand at McGregor.

Finally: I'm getting very excite to see the FH fly.  But first seeing it on the stand in Texas is going to be exciting.

Can't wait!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Moe Grills on 09/24/2014 05:16 pm
  While SpaceX does have an initial test flight of an FH for its 2015 manifest, and the chances appear good that they will try a launch attempt sometime next year, as far as I can tell they don't plan to announce any public rollout in advance of a complete booster. But I wonder if some employee will take a risk and use a concealed cellphone/tablet/iphone camera to give us an inside photo of its assembly.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 09/24/2014 06:42 pm
  While SpaceX does have an initial test flight of an FH for its 2015 manifest, and the chances appear good that they will try a launch attempt sometime next year, as far as I can tell they don't plan to announce any public rollout in advance of a complete booster. But I wonder if some employee will take a risk and use a concealed cellphone/tablet/iphone camera to give us an inside photo of its assembly.

Big no-no. Perhaps instead of potentially getting someone fired, we could ask the good Chris B to inquire as to the status of the first FH next time he gets to talk to SpaceX?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cuddihy on 09/24/2014 08:17 pm
Is the FH pad even going to be complete before the end of 2015? Comments from the Spx Cml Launch Fcility ground breaking seem to indicate that may be at risk.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 09/24/2014 08:26 pm
Is the FH pad even going to be complete before the end of 2015? Comments from the Spx Cml Launch Fcility ground breaking seem to indicate that may be at risk.

FH will launch initially from 39A at Cape Canaveral, or from Vandenburg if that isn't ready in time. Q2 2015 is the most recent timeframe I've heard, and I think that was over the summer sometime.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: oiorionsbelt on 09/24/2014 09:11 pm
Is Vandenberg ready to launch FH today if it were available?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 09/24/2014 09:21 pm
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: docmordrid on 09/24/2014 09:23 pm
Not sure about today, but IIRC they were working on the pad shortly after CASSIOPE.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 09/24/2014 10:19 pm
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.

The basic T/E structure at VFB is already wide enough to handle it, but the most significant mods are going to have to be done to the hold-down system. Right now 4 hold-downs are holding the rocket, but two of them are where FH boosters will attach, so it will need to be redesigned or changed somehow.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dglow on 09/25/2014 04:53 am
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.

The basic T/E structure at VFB is already wide enough to handle it, but the most significant mods are going to have to be done to the hold-down system. Right now 4 hold-downs are holding the rocket, but two of them are where FH boosters will attach, so it will need to be redesigned or changed somehow.

What about prop and lox tankage, water deluge, etc.... did SpaceX already build for 3x F9?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 09/25/2014 05:41 am
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.

The basic T/E structure at VFB is already wide enough to handle it, but the most significant mods are going to have to be done to the hold-down system. Right now 4 hold-downs are holding the rocket, but two of them are where FH boosters will attach, so it will need to be redesigned or changed somehow.

What about prop and lox tankage, water deluge, etc.... did SpaceX already build for 3x F9?

Yes, at least the water deluge. If you look at Cassiope launch footage, you can see the water deluge covering where the boosters would be. I don't think the lox/prop plumbing is a big deal to add to all cores - some of that was likely there from the start.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jcc on 09/25/2014 12:33 pm
I wonder if they plan to use separate RP-1 and LOX fill and drain pipes for each core. That would allow the FH to tank and detank in about the same time as F9. Otherwise, it would take 3 times as long to do that with implications on vehicle processing. Or, they could use pipes that are 3 times bigger, which seems unlikely to me.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Helodriver on 09/25/2014 01:23 pm
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.

The basic T/E structure at VFB is already wide enough to handle it, but the most significant mods are going to have to be done to the hold-down system. Right now 4 hold-downs are holding the rocket, but two of them are where FH boosters will attach, so it will need to be redesigned or changed somehow.

What about prop and lox tankage, water deluge, etc.... did SpaceX already build for 3x F9?

Yes, at least the water deluge. If you look at Cassiope launch footage, you can see the water deluge covering where the boosters would be. I don't think the lox/prop plumbing is a big deal to add to all cores - some of that was likely there from the start.

The answer is more complicated than that.

While the hangar, deluge and TE were sized for Heavy, the full outfitting of the launch mount was never completed. Hold downs and servicing masts were only included for Falcon 9 v 1.1. Launch deck openings for the Heavy boosters were not installed. Work was begun after the CASSIOPE launch to upgrade the launch mount for the Heavy demo flight, but after the announcement of the move of that mission to LC-39A that work has stalled.
So the short answer is, while Heavy looks like it will come to Vandenberg, that pad is not close to ready for it without many months of work yet to do.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: JasonAW3 on 09/25/2014 01:29 pm
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.

The basic T/E structure at VFB is already wide enough to handle it, but the most significant mods are going to have to be done to the hold-down system. Right now 4 hold-downs are holding the rocket, but two of them are where FH boosters will attach, so it will need to be redesigned or changed somehow.

My guess is they'll rotate the whole ring of all four hold downs by about 45 degrees around the hole  Might have to build the center hold downs into paired rigs holding both the core and the inner part of each of the two strap-ons.  It would be normal hold downs for the outer parts of the strap-ons.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jcc on 09/25/2014 04:33 pm
Is Vandenberg ready to launch FH today if it were available?

More or less. The T/E at Vandenburg is already sized for FH. As far as I know, that's the most significant piece of ground equipment that they'd need to redo at SLC40 at the Cape. You'll have to ask someone more qualified than me to get a more detailed answer.

The basic T/E structure at VFB is already wide enough to handle it, but the most significant mods are going to have to be done to the hold-down system. Right now 4 hold-downs are holding the rocket, but two of them are where FH boosters will attach, so it will need to be redesigned or changed somehow.

My guess is they'll rotate the whole ring of all four hold downs by about 45 degrees around the hole  Might have to build the center hold downs into paired rigs holding both the core and the inner part of each of the two strap-ons.  It would be normal hold downs for the outer parts of the strap-ons.

However they do it, it should be compatible with both FH and F9. Or else easy to switch between the two.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/25/2014 04:41 pm

My guess is they'll rotate the whole ring of all four hold downs by about 45 degrees around the hole  Might have to build the center hold downs into paired rigs holding both the core and the inner part of each of the two strap-ons.  It would be normal hold downs for the outer parts of the strap-ons.

Can't, that would rotate the vehicle and the upper stage and fairing umbilicals.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: fthomassy on 09/25/2014 04:50 pm
My guess is they'll rotate the whole ring of all four hold downs by about 45 degrees around the hole  Might have to build the center hold downs into paired rigs holding both the core and the inner part of each of the two strap-ons.  It would be normal hold downs for the outer parts of the strap-ons.
Can't, that would rotate the vehicle and the upper stage and fairing umbilicals.
I would guess that four on v1.1 is more for stability than thrust load.  So remove 2 for the FH center and add 2 each (maybe 3) for FH sides.

Edit: Looking closer at the pics it could be that there will be an entirely new mounting table for FH.  Perhaps they will swap F9 one hole table and FH three hole as needed.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 09/25/2014 05:04 pm

My guess is they'll rotate the whole ring of all four hold downs by about 45 degrees around the hole  Might have to build the center hold downs into paired rigs holding both the core and the inner part of each of the two strap-ons.  It would be normal hold downs for the outer parts of the strap-ons.

Can't, that would rotate the vehicle and the upper stage and fairing umbilicals.

Yes, you absolutely can. There are ways to do it without rotating the entire vehicle by 45 degress. The simplest may be to rotate the octaweb thrust structure 45 degrees before attaching to the first stage tank.

Or even simpler, go back to the CASSIOPE thrust structure, that had 4 extra hold down points, at 45 degrees to the current 4. (see pictures)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/25/2014 05:24 pm

Yes, you absolutely can. There are ways to do it without rotating the entire vehicle by 45 degress. The simplest may be to rotate the octaweb thrust structure 45 degrees before attaching to the first stage tank.


That is not simple or simplest.  there are cabling and tubing that would be affected.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 09/25/2014 05:32 pm

Yes, you absolutely can. There are ways to do it without rotating the entire vehicle by 45 degress. The simplest may be to rotate the octaweb thrust structure 45 degrees before attaching to the first stage tank.


That is not simple or simplest.  there are cabling and tubing that would be affected.

Then the even simpler solution - move (or add back) the CASSIOPE extra hold down points. Most clearly showing in this image:
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: JasonAW3 on 09/25/2014 05:59 pm

My guess is they'll rotate the whole ring of all four hold downs by about 45 degrees around the hole  Might have to build the center hold downs into paired rigs holding both the core and the inner part of each of the two strap-ons.  It would be normal hold downs for the outer parts of the strap-ons.

Can't, that would rotate the vehicle and the upper stage and fairing umbilicals.

If need be, the hold down points on the stage itself could be moved by 45 degrees as well.  If I understand the way that they've put that rocket together, this shouldn't require major structural changes nor wiring and plumbing.  It looks as though each of the outer engines has their wairing and plumbing pre run as a module for fast swap out if needed.  This would avoid extended down time especially for a reusable system.

Fore clarification, I was talking about moving only the attachement hold downs on teh platform AND the attachment points on the first stage. Not rotate the whole stage by 45 degrees.  Sorry I didn't make that clearer.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: PahTo on 09/25/2014 06:12 pm

I think fthomassy has it right (either way).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: somepitch on 09/25/2014 06:40 pm

Yes, you absolutely can. There are ways to do it without rotating the entire vehicle by 45 degress. The simplest may be to rotate the octaweb thrust structure 45 degrees before attaching to the first stage tank.


That is not simple or simplest.  there are cabling and tubing that would be affected.


Then the even simpler solution - move (or add back) the CASSIOPE extra hold down points. Most clearly showing in this image:

Aren't those leg attachment points?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/25/2014 07:01 pm

Then the even simpler solution - move (or add back) the CASSIOPE extra hold down points. Most clearly showing in this image:

Aren't those leg attachment points?

yes, so that isn't a solution.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/25/2014 07:05 pm

Fore clarification, I was talking about moving only the attachement hold downs on teh platform AND the attachment points on the first stage. Not rotate the whole stage by 45 degrees.  Sorry I didn't make that clearer.

There are umbilicals associated with the launcher hold downs.  again, it isn't as simple as moving some attach points.

Anyways, Spacex has already thought this out.  There isn't going to be a new version of the core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: fthomassy on 09/25/2014 07:20 pm
Aren't those leg attachment points?
yes, so that isn't a solution.
Take a closer look.  The 8 symmetric tabs Lars_J pointed out are not leg attachment points.  They are oriented radially.  Pairs of leg pivots are located 90deg apart and one set can be seen in the closeup of the left mount but not at the unused tab in between. 

Edit: But I do agree with Jim's larger point.  Neither the rocket nor the mounts are getting rotated.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 09/25/2014 07:48 pm

Then the even simpler solution - move (or add back) the CASSIOPE extra hold down points. Most clearly showing in this image:

Aren't those leg attachment points?

yes, so that isn't a solution.

Fore clarification, I was talking about moving only the attachement hold downs on teh platform AND the attachment points on the first stage. Not rotate the whole stage by 45 degrees.  Sorry I didn't make that clearer.

There are umbilicals associated with the launcher hold downs.  again, it isn't as simple as moving some attach points.

Sigh... Is it that hard to admit you are wrong, Jim? Do I have to spell this out?
 - The leg attachment points are ABOVE the hold downs.
 - The umbilical port is NOT PART of the hold down or the leg attachment points

Here is an image... I just don't know how I can make myself any clearer.
(image #1, an annotated view of the CRS3 F9 base, with legs)
(image #2, a close up of the CASSIOPE F9 base, showing the umbilical connection mechanism, and how there is ADDITIONAL hold down points)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/25/2014 09:34 pm

Sigh... Is it that hard to admit you are wrong, Jim? Do I have to spell this out?
1.   - The leg attachment points are ABOVE the hold downs.
2.   - The umbilical port is NOT PART of the hold down or the leg attachment points


Only when I am wrong.  So do I have walk you through it?

1.  You don't know that they are hold down points.   There is no documentation that states they can support a loaded vehicle during launch.  For all we know, they are only for the handling rings.

2.  I never said it was.  The vehicle umbilical port is clocked so it interfaces with the launcher hold downs (the ground portion).  Move the vehicle attachments and the umbilicals have to move when them. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 09/25/2014 11:10 pm

Sigh... Is it that hard to admit you are wrong, Jim? Do I have to spell this out?
1.   - The leg attachment points are ABOVE the hold downs.
2.   - The umbilical port is NOT PART of the hold down or the leg attachment points


Only when I am wrong.  So do I have walk you through it?

1.  You don't know that they are hold down points.   There is no documentation that states they can support a loaded vehicle during launch.  For all we know, they are only for the handling rings.

2.  I never said it was.  The vehicle umbilical port is clocked so it interfaces with the launcher hold downs (the ground portion).  Move the vehicle attachments and the umbilicals have to move when them.

1. So this is your way of are admitting that you actually don't know? Take a look at the hold down mechanism, post launch. (Image #1 attached to this point) What else could it hold on to? It certainly isn't supporting anything underneath between the M1Ds.

2. You still don't seem to understand. The umbilical mechanism is independent of the hold down mechanism. Want to rotate the hold-downs 45 degrees? Just move the hold-down near the umbilical connection to the other side of it. The Umbilical connection doesn't need to move. (See image #2 where I color-coded the different mechanisms/interfaces)

I'm not sure why I do this, because you'll still come back and say that moving the hold-downs 45 degrees - "Can't be done". I've shown plenty of evidence that it CAN be done (not that it WILL be done), how about you show some to the opposite effect if you still disagree?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/25/2014 11:27 pm

1.What else could it hold on to?

2. You still don't seem to understand. The umbilical mechanism is independent of the hold down mechanism. Want to rotate the hold-downs 45 degrees? Just move the hold-down near the umbilical connection to the other side of it. The Umbilical connection doesn't need to move. (See image #2 where I color-coded the different mechanisms/interfaces)

3.   I've shown plenty of evidence that it CAN be done (not that it WILL be done), how about you show some to the opposite effect if you still disagree?

1. The support rings for when the vehicle is horizontal.

2.   No that doesn't work. The umbilicals are as close possible to the hold downs that are next and away from the erector.   If the erector is at 12 o'clock, there is a hold down at 12 o'clock and 6 o'clock and the umbilicals are at 1 o'clock and 7 o'clock.

3.  No, you have only played with some photos.  You have not shown that it "can" be done.

For a heavy, I would say there will be only 8 hold downs on the  pad.    The center core will have only two and the side boosters 3 each.  The "unused" ones on the vehicle will be used to connect the core and side boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nomadd on 09/26/2014 02:15 am
 Seems like 10 would be better to keep forces on the cores vertical during ignition and hotfires. I'm trying to wrap my head around the effects of not having hold downs on the core/booster attach points.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: PahTo on 09/26/2014 03:32 am
fthomassy should be happy right about now--I know I am.
The loads imparted on the center core by the boosters (dynamic) are far greater than any experienced on the ground.
Thus, fewer hold downs on the core is no big deal.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lar on 09/26/2014 03:21 pm
How about we all admit that we don't know the exact details, and we have our opinions of how it might be done, and we will find out eventually? If it's really really important to know? Dunno what to tell you. Maybe someone with some contacts could ask some questions but of course SpaceX may not want to answer.

I always respect Jim's input and views... he has forgotten more than most of us ever knew about many space related topics.

I think Lars-J did some useful, no, excellent, analysis as well, and I am convinced it's one possible way things could play out.

But we just don't know.  Remember, be excellent to each other. Thank you.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 09/27/2014 12:39 pm
How about we all admit that we don't know the exact details,


[edited by Lar to soften, and per offline communication...] That may not be true for all of us, some of us might in fact know but possibly can't say. [end edited]
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: parham55 on 09/30/2014 02:44 pm
I seem to remember we were discussing this approximately a year ago. http://forum.nasaspaceflight.com/index.php?topic=32528.msg1097411#msg1097411
I suspect they'll have some sort of launch table swap between 1.1 and FH launches with the FH table having 8 hold downs.
Thanks,
Rob
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: tobi453 on 09/30/2014 10:21 pm
Does anybody know what the payload is on the FH maiden launch ?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 09/30/2014 11:45 pm
Does anybody know what the payload is on the FH maiden launch ?

Last I heard they didn't have one, and will fly without a real payload if they can't find a customer in time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 10/01/2014 12:22 am
Does anybody know what the payload is on the FH maiden launch ?

Last I heard they didn't have one, and will fly without a real payload if they can't find a customer in time.
All they need to do is declare that the not-a-real payload will be ten tons of ball bearings to retrograde GEO, and they'll have a real payload in no time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: woods170 on 10/01/2014 08:57 am
Does anybody know what the payload is on the FH maiden launch ?

Last I heard they didn't have one, and will fly without a real payload if they can't find a customer in time.
All they need to do is declare that the not-a-real payload will be ten tons of ball bearings to retrograde GEO, and they'll have a real payload in no time.
You forgot the sarcasm smiley.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Dudely on 10/01/2014 02:46 pm
My guess is they have the payload but are not willing to discuss it.

My reasoning is that the payload is "exciting" and they want to announce for maximum impact, and they don't want people to know yet in case they change their mind (again!).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 10/01/2014 03:37 pm
My guess is they have the payload but are not willing to discuss it.

My reasoning is that the payload is "exciting" and they want to announce for maximum impact, and they don't want people to know yet in case they change their mind (again!).
I doubt it would be anything too exciting, since they need it to go off without a hitch, but it sure would be cool to see them throw one of their used Dragons on a moon flyby.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 10/01/2014 04:43 pm
My guess is they have the payload but are not willing to discuss it.

My reasoning is that the payload is "exciting" and they want to announce for maximum impact, and they don't want people to know yet in case they change their mind (again!).
I doubt it would be anything too exciting, since they need it to go off without a hitch, but it sure would be cool to see them throw one of their used Dragons on a moon flyby.

Is there any reason to think that Jim's previous response on this is now incorrect? It was penned less than four months ago.


Jim's post is a good point to come back on topic: STP-2 and not FH demo flight.   ;)

They will be one and the same

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 10/01/2014 05:49 pm
Is there any reason to think that Jim's previous response on this is now incorrect? It was penned less than four months ago.
The reasons to think it was incorrect were posted in that same topic.

Jim apparently misunderstood what people were talking about, or was being snide about SpaceX calling a test flight a "demo".  I believe he means to say that STP-2 is a demo flight, for the USAF.  They're sticking a pile of non-critical payloads in an EELV payload carrier, and having SpaceX prove that the Heavy can perform a working launch the way the USAF wants.

The "Falcon Heavy Demo" is in SpaceX's manifest as a separate launch from STP-2.  I'm sure they would call this a development flight, rather than a working flight for the vehicle, and expect any failure not to be held too strongly against them.  If there's someone's payload on it, it will no doubt be steeply discounted.

If there's a problem with the Falcon Heavy Demo, they'll probably do another development flight before STP-2.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: raketa on 10/01/2014 06:00 pm
My guess is they will use refurbish Dragon and will do flyby moon return trajectory. They will show capability deliver spacecraft to Moon , very similar to Mars from delta point of view and  also proof of heat shield returning from moon, will be similar to returning from Mars.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Razvan on 10/01/2014 06:51 pm
Having in mind that each Merlin engine is controlled by three voting computers, each of which has two physical processors that constantly check each other, on one hand and on the other hand, the T-3 secs start engine ignition sequence, I am wondering if the same will apply to the 27 Merlins, accordingly...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 10/01/2014 06:54 pm

Jim apparently misunderstood what people were talking about, or was being snide about SpaceX calling a test flight a "demo".  I believe he means to say that STP-2 is a demo flight, for the USAF.  They're sticking a pile of non-critical payloads in an EELV payload carrier, and having SpaceX prove that the Heavy can perform a working launch the way the USAF wants.

The "Falcon Heavy Demo" is in SpaceX's manifest as a separate launch from STP-2.  I'm sure they would call this a development flight, rather than a working flight for the vehicle, and expect any failure not to be held too strongly against them.  If there's someone's payload on it, it will no doubt be steeply discounted.

If there's a problem with the Falcon Heavy Demo, they'll probably do another development flight before STP-2.

No, I was posting that the payload for the Demo is likely STP-2, regardless what the manifest shows.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 10/01/2014 07:05 pm
My guess is they will use refurbish Dragon and will do flyby moon return trajectory. They will show capability deliver spacecraft to Moon , very similar to Mars from delta point of view and  also proof of heat shield returning from moon, will be similar to returning from Mars.
They maybe able to do this while recovering side boosters.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nindalf on 10/01/2014 07:17 pm
No, I was posting that the payload for the Demo is likely STP-2, regardless what the manifest shows.
Thanks for clearing that up.

But how bad do you think it would be for SpaceX if something goes wrong with STP-2?  If their future with the USAF is riding on it, I'd think they'd want to do at least one test run first, with lower stakes.

USAF might be okay with losing the STP-2 payloads, but SpaceX can't be okay with losing the USAF as a customer.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sghill on 10/01/2014 07:36 pm
No, I was posting that the payload for the Demo is likely STP-2, regardless what the manifest shows.
Thanks for clearing that up.

But how bad do you think it would be for SpaceX if something goes wrong with STP-2?  If their future with the USAF is riding on it, I'd think they'd want to do at least one test run first, with lower stakes.

USAF might be okay with losing the STP-2 payloads, but SpaceX can't be okay with losing the USAF as a customer.

I suppose that depends on the offered launch price and the Air Force's willingness to risk the payload for a free or nearly-free ride uphill.  As long as both parties enter the agreement with their eyes open to the risk, there's no issue in losing the customer- Same goes for Orbcomm and the early Falcon flights.  Looks terrible in the press though!  Even if it doesn't make it off the pad, there's a lot of operational and integration experience working with each other both sides will gain in preparing the innaugural flight that will benefit critical payload launches later on, IMHO.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 10/02/2014 08:11 am

Jim apparently misunderstood what people were talking about, or was being snide about SpaceX calling a test flight a "demo".  I believe he means to say that STP-2 is a demo flight, for the USAF.  They're sticking a pile of non-critical payloads in an EELV payload carrier, and having SpaceX prove that the Heavy can perform a working launch the way the USAF wants.

The "Falcon Heavy Demo" is in SpaceX's manifest as a separate launch from STP-2.  I'm sure they would call this a development flight, rather than a working flight for the vehicle, and expect any failure not to be held too strongly against them.  If there's someone's payload on it, it will no doubt be steeply discounted.

If there's a problem with the Falcon Heavy Demo, they'll probably do another development flight before STP-2.

No, I was posting that the payload for the Demo is likely STP-2, regardless what the manifest shows.
Thanks for updating / confirming.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 10/02/2014 10:51 am
No, I was posting that the payload for the Demo is likely STP-2, regardless what the manifest shows.
Thanks for updating / confirming.

Cheers, Martin

I used the word "likely", I have an out.

Edit/CR - fixed quote
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 10/02/2014 11:29 am
No, I was posting that the payload for the Demo is likely STP-2, regardless what the manifest shows.

Thanks for updating / confirming.

I used the word "likely", I have an out.

Thanks, and noted.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TrevorMonty on 11/05/2014 02:58 am
With recent announcement of 100th Merlin1D, I've just released there will not be any complete FH cores for a while.

Engine 90 will be on CRS5. 100th on what ever follows. Given the number of F9 launches next year it will be while before they have 28 engines to spare for a FH.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Coastal Ron on 11/05/2014 03:44 am
With recent announcement of 100th Merlin1D, I've just released there will not be any complete FH cores for a while.

Engine 90 will be on CRS5. 100th on what ever follows. Given the number of F9 launches next year it will be while before they have 28 engines to spare for a FH.

You can't look at past production rates to predict the future.

SpaceX was supposed to have the capacity to build up to 400 engines per year by the end of this year - which doesn't mean they have to be building that many, just that they have the capability to build and test that many.  So far they seem to be essentially "building to order" and not building ahead, so it's not surprising that we are not seeing an excess of engines coming through.  I'm sure their production schedule is well defined and they will build what they need when they need it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 11/05/2014 03:50 am
I don't think they're leaning their engine production. They have need for lots of engines and are building them as fast as they can.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: macpacheco on 11/05/2014 05:10 am
Thanks for clearing that up.

But how bad do you think it would be for SpaceX if something goes wrong with STP-2?  If their future with the USAF is riding on it, I'd think they'd want to do at least one test run first, with lower stakes.

USAF might be okay with losing the STP-2 payloads, but SpaceX can't be okay with losing the USAF as a customer.

I suppose that depends on the offered launch price and the Air Force's willingness to risk the payload for a free or nearly-free ride uphill.  As long as both parties enter the agreement with their eyes open to the risk, there's no issue in losing the customer- Same goes for Orbcomm and the early Falcon flights.  Looks terrible in the press though!  Even if it doesn't make it off the pad, there's a lot of operational and integration experience working with each other both sides will gain in preparing the innaugural flight that will benefit critical payload launches later on, IMHO.
Are you sure ? SpaceX can't run the risk of loosing a DoD payload even if it's not that critical. USAF generals might be ok with it, but congress will use it to give SpaceX huge grief.
When dealing with DoD, it's heavily political.
But the risk of FH launch failures are lowering with each F9R picture perfect launch. SpaceX might be that confident it their rocket. Just because elon says its 50/50, that might just be a strategy to minimize the impact if the launch actually fails.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jet Black on 11/05/2014 12:08 pm
Thanks for clearing that up.

But how bad do you think it would be for SpaceX if something goes wrong with STP-2?  If their future with the USAF is riding on it, I'd think they'd want to do at least one test run first, with lower stakes.

USAF might be okay with losing the STP-2 payloads, but SpaceX can't be okay with losing the USAF as a customer.

I suppose that depends on the offered launch price and the Air Force's willingness to risk the payload for a free or nearly-free ride uphill.  As long as both parties enter the agreement with their eyes open to the risk, there's no issue in losing the customer- Same goes for Orbcomm and the early Falcon flights.  Looks terrible in the press though!  Even if it doesn't make it off the pad, there's a lot of operational and integration experience working with each other both sides will gain in preparing the innaugural flight that will benefit critical payload launches later on, IMHO.
Are you sure ? SpaceX can't run the risk of loosing a DoD payload even if it's not that critical. USAF generals might be ok with it, but congress will use it to give SpaceX huge grief.
When dealing with DoD, it's heavily political.
But the risk of FH launch failures are lowering with each F9R picture perfect launch. SpaceX might be that confident it their rocket. Just because elon says its 50/50, that might just be a strategy to minimize the impact if the launch actually fails.

50/50 is whether they manage to land the next F9R. I don't think any launch customers are viewing this with anything other than a level of academic interest at the moment. If it fails to land but the launch is perfect, it will not impact on whether people trust their launcher at all (all other rockets have failed at landing* and people still launch on those)

*because they have not even tried!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MattMason on 11/05/2014 02:07 pm
I've not a day available yet to browse the archived threads, so my apologies if I'm asking an already-answered question.

With Pad 39A under SpaceX's care, do they also benefit from the use of the VAB to store/build Heavy stacks? Seems logical that they would since stack assembly on the pad is less practical than using the VAB and the mobile transporter crawler as with STS and Apollo.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 11/05/2014 02:13 pm
I've not a day available yet to browse the archived threads, so my apologies if I'm asking an already-answered question.

With Pad 39A under SpaceX's care, do they also benefit from the use of the VAB to store/build Heavy stacks? Seems logical that they would since stack assembly on the pad is less practical than using the VAB and the mobile transporter crawler as with STS and Apollo.

Certainly not. SpaceX integrates horizontally and transports their rockets horizontally to the pad using a transporter/erector.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sghill on 11/05/2014 03:04 pm
Thanks for clearing that up.

But how bad do you think it would be for SpaceX if something goes wrong with STP-2?  If their future with the USAF is riding on it, I'd think they'd want to do at least one test run first, with lower stakes.

USAF might be okay with losing the STP-2 payloads, but SpaceX can't be okay with losing the USAF as a customer.

I suppose that depends on the offered launch price and the Air Force's willingness to risk the payload for a free or nearly-free ride uphill.  As long as both parties enter the agreement with their eyes open to the risk, there's no issue in losing the customer- Same goes for Orbcomm and the early Falcon flights.  Looks terrible in the press though!  Even if it doesn't make it off the pad, there's a lot of operational and integration experience working with each other both sides will gain in preparing the innaugural flight that will benefit critical payload launches later on, IMHO.
Are you sure ? SpaceX can't run the risk of loosing a DoD payload even if it's not that critical. USAF generals might be ok with it, but congress will use it to give SpaceX huge grief.
When dealing with DoD, it's heavily political.

SpaceX has already blown up 3 DOD payloads.  http://en.wikipedia.org/wiki/Falcon_1

I reiterate.  It's a eyes-wide-open scenario for DOD, they've been willing to launch low-cost non-mission critical payloads on new vehicles for DOD projects that wouldn't have received enough launch funding otherwise, and not just with SpaceX.  The trade-off for low-cost is the risk that the rocket fails.


I've not a day available yet to browse the archived threads, so my apologies if I'm asking an already-answered question.

With Pad 39A under SpaceX's care, do they also benefit from the use of the VAB to store/build Heavy stacks? Seems logical that they would since stack assembly on the pad is less practical than using the VAB and the mobile transporter crawler as with STS and Apollo.

SpaceX is building an HIB at the base of pad 39A to handle this function.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 11/05/2014 03:27 pm

SpaceX has already blown up 3 DOD payloads.  http://en.wikipedia.org/wiki/Falcon_1


Not the "real" DOD when it comes to spacecraft
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MTom on 11/05/2014 07:36 pm
I don't think they're leaning their engine production. They have need for lots of engines and are building them as fast as they can.

I disagree with you.
400 Engines per year means 8 engines per week in average.
There is no reason to build them too early.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dorkmo on 11/06/2014 12:22 am
I don't think they're leaning their engine production. They have need for lots of engines and are building them as fast as they can.

I disagree with you.
400 Engines per year means 8 engines per week in average.
There is no reason to build them too early.

unless you're planning on making some incremental improvements
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jcc on 11/06/2014 01:59 am
I don't think they're leaning their engine production. They have need for lots of engines and are building them as fast as they can.

I disagree with you.
400 Engines per year means 8 engines per week in average.
There is no reason to build them too early.

unless you're planning on making some incremental improvements

If you are planning to make incremental improvements is a good reason not to build them too early.

Still, I have tended to believe that they are producing them as fast as they can, but they need to make a lot of engines to keep up, 10 per F9, 28 per FH, and we heard at the beginning of the year that the engines were limiting stage production. They delayed producing the first FH because they couldn't produce boosters fast enough. Maybe they are holding back engines a bit now that they are ending the year with only 7 launches instead of 10 announced earlier, but they are proposing to double the launches for next year, so they can't slow down too much.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dorkmo on 11/06/2014 03:13 am
though i guess there is danger in spending too much on building up production capacity if theyre planning for reuse.

all of a sudden theyd be making ten times more than they need.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 11/06/2014 10:14 pm
though i guess there is danger in spending too much on building up production capacity if theyre planning for reuse.

all of a sudden theyd be making ten times more than they need.
Except they'd still have some missions that reuse won't work with. If they reuse a rocket stage 10 times, that means each F9 launch uses 2 engines and each Falcon Heavy needs 4 engines. 10 of each a year would be 60 engines (plus, say, 2 expendable Falcon Heavies), which is still 116 engines a year so they may go back down to a couple shifts on engine production (instead of 4), but they wouldn't need to stop production altogether. Currently, they're at about 100 engines per year, right? So 22 launches per year (vast majority of which are partially reusable), which isn't totally unreasonable (about the same as Soyuz and Proton combined) wouldn't need to cut back versus today (though they do seem to want to double that production). Plus they'll need to transition some of their production capacity to working on Raptor which will start entering much more intense development well before they get to 22 launches per year.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Avron on 11/07/2014 10:05 pm
though i guess there is danger in spending too much on building up production capacity if theyre planning for reuse.

all of a sudden theyd be making ten times more than they need.
Except they'd still have some missions that reuse won't work with. If they reuse a rocket stage 10 times, that means each F9 launch uses 2 engines and each Falcon Heavy needs 4 engines. 10 of each a year would be 60 engines (plus, say, 2 expendable Falcon Heavies), which is still 116 engines a year so they may go back down to a couple shifts on engine production (instead of 4), but they wouldn't need to stop production altogether. Currently, they're at about 100 engines per year, right? So 22 launches per year (vast majority of which are partially reusable), which isn't totally unreasonable (about the same as Soyuz and Proton combined) wouldn't need to cut back versus today (though they do seem to want to double that production). Plus they'll need to transition some of their production capacity to working on Raptor which will start entering much more intense development well before they get to 22 launches per year.

so question ,, with reuse around the corner and innovation .. via incremental changes why 10 times the need.. Raptor is really early .. 700 broadband stats ???
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 11/08/2014 12:19 am
though i guess there is danger in spending too much on building up production capacity if theyre planning for reuse.

all of a sudden theyd be making ten times more than they need.
Except they'd still have some missions that reuse won't work with. If they reuse a rocket stage 10 times, that means each F9 launch uses 2 engines and each Falcon Heavy needs 4 engines. 10 of each a year would be 60 engines (plus, say, 2 expendable Falcon Heavies), which is still 116 engines a year so they may go back down to a couple shifts on engine production (instead of 4), but they wouldn't need to stop production altogether. Currently, they're at about 100 engines per year, right? So 22 launches per year (vast majority of which are partially reusable), which isn't totally unreasonable (about the same as Soyuz and Proton combined) wouldn't need to cut back versus today (though they do seem to want to double that production). Plus they'll need to transition some of their production capacity to working on Raptor which will start entering much more intense development well before they get to 22 launches per year.

so question ,, with reuse around the corner and innovation .. via incremental changes why 10 times the need.. Raptor is really early .. 700 broadband stats ???
Could you rephrase that in the form of a clear question?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dorkmo on 11/08/2014 02:03 am
though i guess there is danger in spending too much on building up production capacity if theyre planning for reuse.

all of a sudden theyd be making ten times more than they need.
Except they'd still have some missions that reuse won't work with. If they reuse a rocket stage 10 times, that means each F9 launch uses 2 engines and each Falcon Heavy needs 4 engines. 10 of each a year would be 60 engines (plus, say, 2 expendable Falcon Heavies), which is still 116 engines a year so they may go back down to a couple shifts on engine production (instead of 4), but they wouldn't need to stop production altogether. Currently, they're at about 100 engines per year, right? So 22 launches per year (vast majority of which are partially reusable), which isn't totally unreasonable (about the same as Soyuz and Proton combined) wouldn't need to cut back versus today (though they do seem to want to double that production). Plus they'll need to transition some of their production capacity to working on Raptor which will start entering much more intense development well before they get to 22 launches per year.

so question ,, with reuse around the corner and innovation .. via incremental changes why 10 times the need.. Raptor is really early .. 700 broadband stats ???
Could you rephrase that in the form of a clear question?

i think he's asking why i claimed they'd be making 10 fold the needed engines. the answer would be because for every reusable launch they would no longer need to make the 9 engines for the first stage and only need to make 1 engine for the second.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 11/08/2014 02:12 am
Yeah, I thought it was pretty clear. For every 9 or 10 launches, you'd need a new first stage or booster (guess), and every launch needs a new Merlin 1D Vac, plus you may have occasional fully expendable launches. Together, at a total rate of 10 F9Rs, 10 FH (part reuse), and 2 expendable FHs, you need over 100 engines per year.

They also would have the breathing room to enable Raptor development and initial production (same timeframe as a 22-per-year launch rate).

Bottom line: Their current rate of production of about 100 engines per year (which they hope to double) would be fine without having to downsize or mothball their production facility (at most cut back on the night shift).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dorkmo on 11/08/2014 02:30 am
i just read where the 700 number came from

"In talks with industry executives, Messrs. Musk and Wyler have discussed launching around 700 satellites, each weighing less than 250 pounds"
http://arstechnica.com/information-technology/2014/11/elon-musk-considers-building-smaller-cheaper-internet-satellites/



Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Avron on 11/08/2014 08:15 pm
i just read where the 700 number came from

"In talks with industry executives, Messrs. Musk and Wyler have discussed launching around 700 satellites, each weighing less than 250 pounds"
http://arstechnica.com/information-technology/2014/11/elon-musk-considers-building-smaller-cheaper-internet-satellites/





And thus the need for so many engines.. If the concept is incremental change, then you would make the engines as needed, if you are close to reuse then you need a lot less, unless you where going to use the engines soon.  FH will use a lot of engines quickly, and we know now that it may be a little longer until the core stage of the FH is recovered. So even with reuse of the outer cores, a lot of engines will be used. The question would be why so many engines produced, if they where not going to be used really soon.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: aero on 11/09/2014 04:26 am
Depends a lot on the orbit altitude. At 250 kg/satellite, that is 4 satellites/tonne. For the FH, with 50 tonnes to LEO, ie. 185 km altitude, 700 satellites is like 4 H launches. With booster recovery, core and US expended, that is 40 engines expended and 72 engines recovered but heavily used.

I expect the satellite's orbits will be somewhat higher than 185 km though. The higher the orbit the more energy required so fewer satellites per FH launch. So the number of Merlin 1D's expended to launch 700 satellites depends on the satellite orbit altitude.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 11/09/2014 07:34 am
Depends a lot on the orbit altitude. At 250 kg/satellite, that is 4 satellites/tonne. For the FH, with 50 tonnes to LEO, ie. 185 km altitude, 700 satellites is like 4 H launches. With booster recovery, core and US expended, that is 40 engines expended and 72 engines recovered but heavily used.

I expect the satellite's orbits will be somewhat higher than 185 km though. The higher the orbit the more energy required so fewer satellites per FH launch. So the number of Merlin 1D's expended to launch 700 satellites depends on the satellite orbit altitude.
Upperstage recovery is made incredibly difficult by having to come back from GTO.

If SpaceX had a large number of LEO flights, then it might make sense for them to reconsider their decision not to pursue u/s recovery with Falcon.

Especially in light of my supposition (someone check me), that Falcon PLF would be heavily volume limited. A LEO CommSat constellation is going to rely on large antennae. (Much better than the handsets needing large antennae.)

Lots of mass margin to build in recovery experiments.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 11/09/2014 08:52 am
Upperstage recovery is made incredibly difficult by having to come back from GTO.

No, GTO is elliptical and deorbit requires very little fuel. It is the payload penalty that bugs the economy. We have to assume that the heatshield can handle the speed. After all they will want to enter Mars with MCT at high speed as well as entering earth atmosphere at return. RTLS may be more difficult. It would take time until the trajectory passes over the launch site again.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 11/09/2014 01:38 pm
just an idea, that popped up in my mind:

let's work with the assumpion of robotbeat with 10 F9R, 10 FH (part or fully reusable) and 2 FH expendable launches per year:

a F9R or FH(R) launch, and they get the full first stage of F9R back, and at least the 2 boosters from a FH-launch.

the expendable launches (FH at full capacity, or FH central stage) could be done with reused systems after 8-9 or so launches). since there are customers who demand fresh and unused equipment (as far as I know NASA, who also pays for that fresh stage), they could use the recovered stages from NASA-flights for other flights, and at the end of the lifetime, they use it as expendable launch vehicles.

one other thing, that I wonder about: I think, producing one raptor engine is easier than producing 9 merlin engines, yet it is stronger (as far as the last released values show). would a FH work, which contains the 2 boosters with 2x9 merlins, one central stage with 1 raptor (which either needs to be modified for kerosene, or otherwise fuel crossfeed isn't available), and an upper stage with one merlin 1Vac. the drawback would be the slightly reduced security, a failure of 1 merlin engine is irrelevant (unless it's the one of the upper stage), but loosing the raptor engine would end that flight.

this would reqire spaceX to produce 22 merlin 1 vac engines, at least 27 merlin 1 engines and up to 10 raptor engines (maybe less, if the central core of FH can be recovered aswell, thus needing a stage with 9 merlins), maybe more merlins if some of the 10 F9R flights are done for NASA and their requirement of fresh equipment.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Eerie on 11/09/2014 03:21 pm
just an idea, that popped up in my mind:

Assuming that BFR with Raptor will succeed at being fully reusable (both stages), it is likely that the entire Falcon/Merlin line will be closed.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 11/09/2014 03:55 pm
just an idea, that popped up in my mind:

Assuming that BFR with Raptor will succeed at being fully reusable (both stages), it is likely that the entire Falcon/Merlin line will be closed.

After a couple years of overlap.  The BFR will have to have to well proven before a by then proven and paid for system is sidelined.  Having redundancy is awfully nice.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Vultur on 11/09/2014 04:05 pm
just an idea, that popped up in my mind:

Assuming that BFR with Raptor will succeed at being fully reusable (both stages), it is likely that the entire Falcon/Merlin line will be closed.

BFR is awfully big for small payloads. FH disappearing, sure, but I'm not so sure about F9.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 11/09/2014 04:24 pm
just an idea, that popped up in my mind:

Assuming that BFR with Raptor will succeed at being fully reusable (both stages), it is likely that the entire Falcon/Merlin line will be closed.

BFR is awfully big for small payloads. FH disappearing, sure, but I'm not so sure about F9.

I can see a future (say, 15 years from now) where a fully reusable BFR is able to apply lessons learned from F9 so well that it is actually cheaper per flight than F9 with an expendable upper stage. In that scenario, I would expect a sort of F9 2.0 eventually (another 5+ years later) that would be even cheaper and be fully reusable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Eerie on 11/09/2014 05:15 pm
I can see a future (say, 15 years from now) where a fully reusable BFR is able to apply lessons learned from F9 so well that it is actually cheaper per flight than F9 with an expendable upper stage. In that scenario, I would expect a sort of F9 2.0 eventually (another 5+ years later) that would be even cheaper and be fully reusable.

Or maybe people will switch to heavier satellites. If launch price is low enough, it will make sense to optimize the satellite by cost instead of by mass. Stuff like less efficient but cheaper solar panels, for example. If mass is not an issue, why not just put more solar panels? Why not use steel as a structural element? Put a bigger fuel tank to ensure de-orbiting. Et cetera...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 11/09/2014 07:30 pm
for satellites up to 7 tons, FH fully reuseable will be the LV to go. that's a whole lot more than a todays communication or TV sat weighs. and then let's see how often the refurbished stages will work. maybe the first launch costs most, and the 2nd-5th launch costs less, the 6-10th launch is again cheaper, and from the 11th on, it's cheap and they just launch stuff to space stations (I expect more than one in a few years). to minimize the loss of material (and therefore money), those launches could just send an container up, which then gets captured by a dragon capsule, and then delivered to the station. minimizing the amount of flight-hardware (and therefore valueable goods) launched by the rocket.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 11/10/2014 09:45 am


for satellites up to 7 tons, FH fully reuseable will be the LV to go.

Just to clarify - it's all three cores reused, but u/s expended.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 11/10/2014 09:48 am


Upperstage recovery is made incredibly difficult by having to come back from GTO.

No, GTO is elliptical and deorbit requires very little fuel. It is the payload penalty that bugs the economy. We have to assume that the heatshield can handle the speed. After all they will want to enter Mars with MCT at high speed as well as entering earth atmosphere at return. RTLS may be more difficult. It would take time until the trajectory passes over the launch site again.

Thanks for the correction. Agree it is the penalty of carrying the recovery hardware & prop to GTO.

But the argument I was making is unaffected by the distinction.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 11/10/2014 10:34 am
thanks for pointing it out.

I meant the system with expendable upper stage. I used the term fully reusable to distinguish it from partial reusable, where just the 2 booster-cores land, and the central core is expendable.

maybe a reusable upper stage would work for falcon heavy, as (as far as I know) the reusable upper stage would be to heavy for a normal F9, FH could be strong enough to do so. and if such a completely reusable FH delivers as much mass as a normal F9R, then it's just an economic question... which system is cheaper.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Burninate on 11/10/2014 11:26 am
just an idea, that popped up in my mind:

Assuming that BFR with Raptor will succeed at being fully reusable (both stages), it is likely that the entire Falcon/Merlin line will be closed.

BFR is awfully big for small payloads. FH disappearing, sure, but I'm not so sure about F9.

I can see a future (say, 15 years from now) where a fully reusable BFR is able to apply lessons learned from F9 so well that it is actually cheaper per flight than F9 with an expendable upper stage. In that scenario, I would expect a sort of F9 2.0 eventually (another 5+ years later) that would be even cheaper and be fully reusable.

I look at it from the other direction.  F9 is a launch vehicle optimized largely to take advantage of the US road transportation network - it's as big as it can practically be and still fit on the highway.  SpaceX is presently working on a barge-based supplychain, which is not constrained to 3.7m diameter.  They're also working on methane engines.  BFR is way too large for everyday commercial launch.

I think it's pretty likely that >3.7m diameter, methane, and reusable upper stage get combined at some point in a medium-sized LV, though I suspect this isn't really a near-term goal.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 11/10/2014 12:07 pm
....They're also working on methane engines.  BFR is way too large for everyday commercial launch.

I think it's pretty likely that >3.7m diameter, methane, and reusable upper stage get combined at some point in a medium-sized LV, though I suspect this isn't really a near-term goal.

Oh no, now you're going to reap the whirlwind.  Each time I've suggested something similar, that the BFR is too big and that a smaller Raptor powered vehicle makes sense I've been lit up.

However, I agree with you that as people envision the BFR, with 9 engines is massive.  I think a 4 or 5 Raptor engine rocket is sufficiently large enough to be considered a Big Freakin' Rocket.  (6.5-8 million pounds of thrust!)

A single Raptor engine core, and a FH like 3 core model (5 million pounds thrust) would provide all that is needed for anything in the commercial realm for the foreseeable future.  However, that leaves an opening for a methane upper stage engine that has not been mentioned.  They could keep using the Merlin 1D Vac.



Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 11/10/2014 12:12 pm
Not reusable, then.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 11/10/2014 01:01 pm
Not reusable, then.

Right and therefore massively expensive.

For an economic medium sized launcher I would love to see a 7 engine vehicle. Perfect spacing of the engines, cheaper than 9 engines and hopefully with sufficient throttle capacity it can land on the central engine. And certainly with a capacity that makes a heavy unnecessary. Everything beyond would go on a single stick BFR.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: pagheca on 11/10/2014 01:46 pm
Not reusable, then.

Right and therefore massively expensive.

For an economic medium sized launcher I would love to see a 7 engine vehicle. Perfect spacing of the engines, cheaper than 9 engines and hopefully with sufficient throttle capacity it can land on the central engine. And certainly with a capacity that makes a heavy unnecessary. Everything beyond would go on a single stick BFR.

I have been wondering too why this "natural" configuration is so rare (actually, I cannot cite a stage with seven engines...).

Does someone have an hint? Maybe the benefit of the equally spaced is irrelevant because the central one would be subject to some sort of resonances and/or heating?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cuddihy on 11/10/2014 04:32 pm
I can see a future (say, 15 years from now) where a fully reusable BFR is able to apply lessons learned from F9 so well that it is actually cheaper per flight than F9 with an expendable upper stage. In that scenario, I would expect a sort of F9 2.0 eventually (another 5+ years later) that would be even cheaper and be fully reusable.

Or maybe people will switch to heavier satellites. If launch price is low enough, it will make sense to optimize the satellite by cost instead of by mass. Stuff like less efficient but cheaper solar panels, for example. If mass is not an issue, why not just put more solar panels? Why not use steel as a structural element? Put a bigger fuel tank to ensure de-orbiting. Et cetera...

This is backwards IMO. Satellite costs are dominated by Integration, testing, & engineering costs. Component costs are far down the list. So lots of little satellites and common buses would do more to reduce costs than more mass available. Cf Iridium, Orbcomm.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 11/10/2014 04:41 pm


thanks for pointing it out.

I meant the system with expendable upper stage. I used the term fully reusable to distinguish it from partial reusable, where just the 2 booster-cores land, and the central core is expendable.

maybe a reusable upper stage would work for falcon heavy, as (as far as I know) the reusable upper stage would be to heavy for a normal F9, FH could be strong enough to do so. and if such a completely reusable FH delivers as much mass as a normal F9R, then it's just an economic question... which system is cheaper.

I think we need better terminology for the various classes of reuse (boosters / core / boosters + core / combinations with upperstage / combinations with RTLS / combinations with sea landing). Something like FH-NRRE (no crossfeed, boosters RTLS, core RTLS, US expended) or FH-CRFE (crossfeed, boosters RTLS, core FTSL [barge landing], US expended)

U/s recovery - agreed. I'm holding my breath that Jon Goff's work on Magnetoshell Aero Capture will bring down the mass penalty of recovery.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 11/10/2014 05:10 pm
I can see a future (say, 15 years from now) where a fully reusable BFR is able to apply lessons learned from F9 so well that it is actually cheaper per flight than F9 with an expendable upper stage. In that scenario, I would expect a sort of F9 2.0 eventually (another 5+ years later) that would be even cheaper and be fully reusable.

Or maybe people will switch to heavier satellites. If launch price is low enough, it will make sense to optimize the satellite by cost instead of by mass. Stuff like less efficient but cheaper solar panels, for example. If mass is not an issue, why not just put more solar panels? Why not use steel as a structural element? Put a bigger fuel tank to ensure de-orbiting. Et cetera...

This is backwards IMO. Satellite costs are dominated by Integration, testing, & engineering costs. Component costs are far down the list. So lots of little satellites and common buses would do more to reduce costs than more mass available. Cf Iridium, Orbcomm.
The argument is that using greater margins in structure, power, thermal areas plus modular (as opposed to integrated) interfaces may make testing and development plus integration requirements a lot easier and faster. If you can throw in a factor of safety of 4, you don't need to track down the third digit of certainty in your design, the logic goes. Aerospace engineering becomes more like building houses, where generous margins and factors of safety allow you to truncate analysis earlier without reducing safety.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 11/10/2014 05:31 pm
Not reusable, then.

Are you saying the Merlin 1D Vac not reuseable?  The engine itself should be, the stage around it would have to be made reuseable.  If a reuseable FH US is developed then it exists and is sitting there ready for use.

Regarding the magical engine configuration requiring a center engine and deep throttling, it seems to me that Super Dracos placed at the intertank or top of stage would do a lovely job of setting a stage on the ground.  Retroburns could be managed with 2 outboard engines.

It's convenient that the size of the Merlin 1 has worked with the ability to land with the main engine.  But I don't think we should all get stuck on the idea of all re-useable rockets needing to work that way in the future.  Especially with cryogenic fueled upper stages.  Those are going to need store-able propellants.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Razvan on 11/14/2014 10:23 pm
Falcon Heavy is going to carry the ViaSat2
ViaSat-2 Launch Contract Goes to SpaceX as Arianespace Sits out Competition (Space News)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: AncientU on 11/15/2014 01:42 am
Here's the link:
http://www.spacenews.com/article/launch-report/42557viasat-2-launch-contract-goes-to-spacex-as-arianespace-sits-out
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: catdlr on 11/19/2014 11:00 pm
U.S. Air Force 'pretty optimistic' about SpaceX certification

Quote
A top U.S. Air Force official on Wednesday said she is "pretty optimistic" that privately held Space Exploration Technologies will eventually be certified to launch U.S. military satellites into orbit but declined comment on the timing of such an action.

http://news.yahoo.com/u-air-force-pretty-optimistic-spacex-certification-184329209.html
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: a_langwich on 11/20/2014 12:10 am
Has there already been speculation about which island SpaceX might choose to aim booster cores at, in the event RTLS isn't possible?

Anybody looking at Dogleg or the other real estate ventures to see if they've bought some island?   :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: a_langwich on 11/20/2014 12:57 am
If they do the same for heavy flights from the Cape (land at a distance for flights with too little deltaV for RTLS), maybe they can buy the island next to Branson's little Caribbean getaway (Necker Island).  That way, Elon can say to Branson like he said to Bezos "you should get into the space business, it's a lot of fun."

Actually, Necker Island looks pretty close to Puerto Rico, so perhaps SpaceX has already looked at a nearby piece of land.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nimbostratus on 11/20/2014 02:38 am
Has there already been speculation about which island SpaceX might choose to aim booster cores at, in the event RTLS isn't possible?

Anybody looking at Dogleg or the other real estate ventures to see if they've bought some island?   :)

How about Falcon Heavy taking off at Boca Chica and recovering the core in Florida, while the 2 boosters to RTLS?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: JBF on 11/20/2014 11:09 am
Has there already been speculation about which island SpaceX might choose to aim booster cores at, in the event RTLS isn't possible?

Anybody looking at Dogleg or the other real estate ventures to see if they've bought some island?   :)

How about Falcon Heavy taking off at Boca Chica and recovering the core in Florida, while the 2 boosters to RTLS?

Elon has talked about this scenario, and stated the distance is too far.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 11/20/2014 11:23 am


Has there already been speculation about which island SpaceX might choose to aim booster cores at, in the event RTLS isn't possible?

Anybody looking at Dogleg or the other real estate ventures to see if they've bought some island?   :)

How about Falcon Heavy taking off at Boca Chica and recovering the core in Florida, while the 2 boosters to RTLS?

Elon has talked about this scenario, and stated the distance is too far.

No, he said the core would overshoot Florida, which seems to imply it could land there with a much smaller braking / boostback burn than RTLS.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 11/20/2014 05:08 pm
Has there already been speculation about which island SpaceX might choose to aim booster cores at, in the event RTLS isn't possible?

There was a specific west coast island mentioned in L2 (http://forum.nasaspaceflight.com/index.php?topic=34549.msg1187899#msg1187899) but  other options are being considered (http://forum.nasaspaceflight.com/index.php?topic=34549.msg1236272#msg1236272).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Roy_H on 11/20/2014 07:09 pm

How about Falcon Heavy taking off at Boca Chica and recovering the core in Florida, while the 2 boosters to RTLS?

Elon has talked about this scenario, and stated the distance is too far.

No, he said the core would overshoot Florida, which seems to imply it could land there with a much smaller braking / boostback burn than RTLS.

Cheers, Martin
[/quote]

I think there is considerable confusion about this. The west coast of Florida, near south tip would seem to be about right according to some calculations done (can't remember by who) and overshooting Florida would apply to the expendable version.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 11/20/2014 10:40 pm
Please remember that since the boosters have more propellent load, if the core throttles after MaxQ then boosters and cores would deplete at about the same time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 11/20/2014 10:41 pm
JP Burke (yatpay):
@elonmusk Is it possible to launch from Texas and land in Florida?
http://twitter.com/yatpay/status/330394578442133504


Elon Musk (elonmusk):
@yatpay Side boosters fall short & center core goes too far + Florida is heavily populated. Landing permission tricky :)
http://twitter.com/elonmusk/status/330395232564826112
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: catdlr on 11/27/2014 12:16 am
SpaceX may upset firm's monopoly in launching Air Force satellites

http://www.latimes.com/business/la-fi-spacex-satellites-20141126-story.html#page=1

Quote
Etrepreneur Elon Musk and his upstart company SpaceX are on the verge of upsetting a cozy and pricey military deal that for years has given two aerospace giants the exclusive right to launch the Air Force's most crucial satellites into orbit.

Quote
Air Force officials are in the final stages of a years-long, detailed review of the rocket company's launches and operations. A decision on whether to certify SpaceX for the launches, they said, is expected next month.

Photo Cred: Ron Lin / SpaceX
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cuddihy on 11/30/2014 04:55 am
Wow. LA Times article from today could have been written five years ago. Kind of silly to still refer to SpaceX as upstart.

* let me rephrase -- headline and subhead could be from five years ago
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Chris Bergin on 12/02/2014 03:09 am
Try not to lick the screen when you see this, but we've released one of the renderings out of L2 - by Nathan Koga - showing SLS on 39B and Falcon Heavy on 39A:

http://forum.nasaspaceflight.com/index.php?topic=36205.0
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: b ramsey on 12/02/2014 03:59 am
Very nice realistic looking rendering, but very much a fantasy, and you know which vehicle I am referring too.       
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: darkenfast on 12/02/2014 04:49 am
Very nice artwork, though!
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: JWarner on 12/02/2014 01:42 pm
Very nice art work!

One small nit, by the time SLS is supposed to be there the rotating service structure will be gone.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: newpylong on 12/02/2014 03:18 pm
Very nice realistic looking rendering, but very much a fantasy, and you know which vehicle I am referring too.       

Always has to be one.

This rendering with utmost certainty will become reality. Like or not.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 12/02/2014 10:07 pm
Very nice realistic looking rendering, but very much a fantasy, and you know which vehicle I am referring too.       

Always has to be one.

This rendering with utmost certainty will become reality. Like or not.
It is my semi-fantasy after the current supply of RS-25 get used up, pad 39B will be re-config to the upcoming pad 39A design. So we can have the spectacular of up to   6    7  fly back cores to the the Cape.  :)

Again it is a fantasy vision.

edit: Forgot about the possibility of additional F9R launch from pad 40. Disregarding the remote possibility that pad 40 will be upgraded for the FH.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mr. mark on 12/03/2014 02:10 am
Interesting future image that I saw online. Source: nbcnews.com
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: e of pi on 12/03/2014 02:12 am
Interesting future image that I saw online. Source: nbcnews.com

Might want to check NBC's source. ;)

Try not to lick the screen when you see this, but we've released one of the renderings out of L2 - by Nathan Koga - showing SLS on 39B and Falcon Heavy on 39A:

http://forum.nasaspaceflight.com/index.php?topic=36205.0

EDIT: I just found the article on their site (http://www.nbcnews.com/science/space/testing-nasa-how-space-exploration-will-work-orion-era-n259306), and I see they did credit the original source there. Nice piece, actually, and I retract the critique I'd originally had about not crediting content.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mr. mark on 12/03/2014 02:16 am
Oops, didn't see Chris' post. I'll leave it up here just because It's Falcon Heavy related.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sdsds on 12/03/2014 04:07 am
6 fly back cores to the the Cape.

Nice vision! I would love to see one pad at LC-39 outfitted for a crewed payload, and the other for a payload consisting of a loiter-capable Earth-orbit departure stage. That enables a two launch mission, with Earth-orbit rendezvous.

Hmm. Where have we seen that vision before? ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Mader Levap on 12/07/2014 09:47 pm
Very nice realistic looking rendering, but very much a fantasy, and you know which vehicle I am referring too.
Always has to be one. This rendering with utmost certainty will become reality. Like or not.
Okay, then. Quoted and saved link. See you in 2018.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 12/08/2014 01:04 am
As FH is slated to fly from LC-39A, I thought this article/video from CBSnews.com might be of interest:

http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: woods170 on 12/08/2014 07:12 am
As FH is slated to fly from LC-39A, I thought this article/video from CBSnews.com might be of interest:

http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads (http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads)

I don't see the problem. The US has an army corps of engineers. They should rebuild the sea-wall (restore the dunes and the beach). (http://www1.inecol.edu.mx/repara/download/III_1_BeachandDuneRestoration1.pdf) And if that is out of their league, they can always call the Dutch. We have ample experience protecting vital structures against the sea. :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 12/08/2014 07:23 am
As FH is slated to fly from LC-39A, I thought this article/video from CBSnews.com might be of interest:

http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads (http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads)

I don't see the problem. The US has an army corps of engineers. They should rebuild the sea-wall (restore the dunes and the beach). (http://www1.inecol.edu.mx/repara/download/III_1_BeachandDuneRestoration1.pdf) And if that is out of their league, they can always call the Dutch. We have ample experience protecting vital structures against the sea. :)

The CBS-report states that NASA is doing that right now.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: woods170 on 12/08/2014 08:19 am
As FH is slated to fly from LC-39A, I thought this article/video from CBSnews.com might be of interest:

http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads (http://www.cbsnews.com/news/climate-change-threatens-vital-nasa-launch-pads)

I don't see the problem. The US has an army corps of engineers. They should rebuild the sea-wall (restore the dunes and the beach). (http://www1.inecol.edu.mx/repara/download/III_1_BeachandDuneRestoration1.pdf) And if that is out of their league, they can always call the Dutch. We have ample experience protecting vital structures against the sea. :)

The CBS-report states that NASA is doing that right now.
Well, not NASA itself. Space engineers make for lousy sea wall constructors. The work is done by contractors under supervision of some folks (http://www.usace.army.mil/Home.aspx) who are much better at this stuff.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Roy_H on 12/09/2014 12:04 am
I know SpaceX has stated that they intend to build both cross-feed and non-cross-feed versions of the Falcon Heavy, but I think the initial versions will all be cross-feed. To be certified for the DoD, SpaceX needs 3 flights. And I would think they would require a separate certification for the cross-feed if they only certified the non-cross-feed first. But if SpaceX certifies the cross-feed version first, they might not have to re-certify the simpler version. All this brings me to the conclusion that the first 4 flights will be all cross-feed, whether they need that performance or not. What do you guys think?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 12/09/2014 02:19 am
I think it partly depends on how much money SpaceX wants to spend and how long they want to take to get a paying vehicle launching payloads.  But more importantly, is there a defense payload in the next 5 or so years that SpaceX needs cross feed capability to put it in orbit.  Then there is no need to certify the cross feed version.

Also, imagine how long and slow getting crossfeed through the certification process will be,.
 since no one has done it before.

The development of cross feed, I think, will be a slow tedious process.  Lots of ground testing in Texas, and eventually partial and conservative operation in flight to build confidence before realizing the full potential, if it is even possible.


Tying a few reuseable ideas together, I think a medium term goal for a SpaceX is to use a FH with cross feed that improves FH performance enough to enable RTLS of the outboard boosters, recovery down range and a reuseable US.

I think SpaceX is building the pieces slowly to make a fully reuseable FH possible in the 3-4 year time range.  Giving SpaceX pricing power and a flight rate to capture most of the worlds commercial market.

Edit:
Clearing up my late night ramblings and...

I think it's reasonable to expect SpaceX to design the structure, engine area, parts of the piping configuration to accommodate the crossfeed piping so that there are minimal changes in the shop for the manufacture of each one.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/09/2014 02:21 am
I believe that it will also depend on DoD required performance. If FH can achieve it without cross feed, DoD will probably rather save the risk. So it might be in SpaceX own best interest not to fly cross feed until DoD gets their certification package.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Eerie on 12/09/2014 11:07 am
Is there any indication that cross-feed is actually planned in the short term? Judging by the lack of comments from SpaceX, I'm under an impression cross-feed is somewhere in the future...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 12/09/2014 11:49 am
I recall earlier statements that the first flight(s) will not have crossfeed. But things change. With the outer cores crossfeeding they are depleted early and RTLS can be done with smaller payload penalty. Recovering the central core becomes more difficult though. So who knows all the trades considered and made, especially with regard to reuse of all cores?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Eerie on 12/09/2014 12:51 pm
I recall earlier statements that the first flight(s) will not have crossfeed. But things change. With the outer cores crossfeeding they are depleted early and RTLS can be done with smaller payload penalty. Recovering the central core becomes more difficult though. So who knows all the trades considered and made, especially with regard to reuse of all cores?

Without cross-feed, F9H boosters should go as high as F9 first stage, right? So if F9 first stage can be saved as is, there is no need for cross-feed to save F9H boosters, it just adds failure modes.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 12/09/2014 12:55 pm
Without cross-feed, F9H boosters should go as high as F9 first stage, right?

Strap-on cores will be depleted early, with or without crossfeed. The center core would throttle down shortly after liftoff to conserve propellant la Delta IV Heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Sohl on 12/09/2014 01:09 pm
Strap-on cores will be depleted early, with or without crossfeed. The center core would throttle down shortly after liftoff to conserve propellant la Delta IV Heavy.

Note that the Delta IV Heavy is used for the biggest current DoD launches, so chances are that mission planners would be only considering payloads within the Delta IV Heavy capability for the time being.  So if no-crossfeed and throttle down of central core is good enough for all current large DoD payloads, SpaceX may not feel much demand to jump into crossfeed soon, as cool as it would be to see as a rocket fan.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 12/09/2014 01:29 pm
So if no-crossfeed and throttle down of central core is good enough for all current large DoD payloads, SpaceX may not feel much demand to jump into crossfeed soon, as cool as it would be to see as a rocket fan.

Perhaps. The difference in complexity would be obvious, but it seems to me F9 cores are less suited to non-crossfeed operation than D-IV cores because of their shorter burn time (roughly 1/2 as long). You have to throttle down the center core at some point shortly after liftoff to balance gravity losses vs. propellant conservation, but since a F9 1st stage provides less total delta-V to a launch than a D-IV first stage, the staggered staging will also provide less of a benefit than it does with a Delta IV Heavy.

Simply speaking, throttling down at say 30 sec will leave less propellant in core of FH than DIVH after strap-on burnout. I think. I don't know how differences in lowest throttle setting (they seem roughly similar) and lower Isp on F9 making T/W increase faster play into this.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 12/09/2014 01:36 pm
SpaceX will likely use Falcon Heavy for Mars precursor missions. Like sending rovers on Red Dragon. Crossfeed may well make the difference between three expended cores and recovering the outer cores for that purpose.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/09/2014 03:07 pm
Without cross-feed, F9H boosters should go as high as F9 first stage, right?

Strap-on cores will be depleted early, with or without crossfeed. The center core would throttle down shortly after liftoff to conserve propellant la Delta IV Heavy.
FH boosters have more propellant than the core. Doing some back of the envelop calculations, I got that throttling center down to 70% at maxq would mean that boosters and core deplete at the same time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 12/09/2014 03:22 pm
FH boosters have more propellant than the core.

I've seen the rendering.

Quote
Doing some back of the envelop calculations, I got that throttling center down to 70% at maxq would mean that boosters and core deplete at the same time.

Yes, but what's special about max Q? You want to make the best trade between lowest gravity losses and highest amount of prop remaining in the core. From an energy management standpoint, it's just not optimal to drag all three cores to the same burnout velocity.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 12/09/2014 03:31 pm
...as cool as it would be to see as a rocket fan.

It would be so very cool. 

Regarding non cross feed performance, even 5, 10 or 20 seconds after separation at maximum thrust would help since the G's are higher at that part of the flight.  5 seconds at the end of first stage is worth more than 5 seconds at the start.

Also, every meter per second helps make up for the less than optimized RP1 upper stage.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: groundbound on 12/09/2014 05:10 pm
I would argue that one of the key pieces of input data for all of this is not in yet: schedule information.

FH is getting a late start, FH is also  believed by many to be a stopgap solution. If FH pushes out more and Raptor development goes better than expected, at some point you have to say the effort of doing a lot of extra development on FH is just not worth the return. IMO this is likely to be the fate of all plans for FH high energy upper stage redesign, but it also might apply to crossfeed.

Note the "we don't know yet" argument could cut both ways. If Raptor hits a bunch of roadblocks, FH might not only see crossfeed developed, but there might be work on a higher energy second stage. More revenue from Falcon family in this decade might be critical path to getting BFR ever.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 12/09/2014 06:25 pm
regarding this "we don't know yet": so far we know, that elon musk has a very ambitious plan regarding mars. and I sometimes think: what needs to be done, if something is a showstopper in the raptor-development. as far as we know, building such large rocket engines and rockets (like BFR) is quite something difficult.

so assuming, they can't do BFR (would be a sad thing), and assuming that musk wouldn't stop at such a point, is it possible to evolve falcon heavy the same way ULA wanted to do with the delta IV or the russians plan wit angara, and add more booster-stages. a falcon very heavy with the central core and 4 boosters, and a falcon ultra heavy with the central core and 6 boosters. would the structure be capable of holding that together? and I assume that managing 45 or even 63 engines is everything but trivial.

and such an amount of boosters requires a newly designed upper stage, the same one as they use in a normal falcon 9 would be way too small. I don't know anything about the capabilities of such a rocket, I assume 100t LEO should be easily achievable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 12/09/2014 08:19 pm
regarding this "we don't know yet": so far we know, that elon musk has a very ambitious plan regarding mars. and I sometimes think: what needs to be done, if something is a showstopper in the raptor-development. as far as we know, building such large rocket engines and rockets (like BFR) is quite something difficult.

so assuming, they can't do BFR (would be a sad thing), and assuming that musk wouldn't stop at such a point, is it possible to evolve falcon heavy the same way ULA wanted to do with the delta IV or the russians plan wit angara, and add more booster-stages. a falcon very heavy with the central core and 4 boosters, and a falcon ultra heavy with the central core and 6 boosters. would the structure be capable of holding that together? and I assume that managing 45 or even 63 engines is everything but trivial.

and such an amount of boosters requires a newly designed upper stage, the same one as they use in a normal falcon 9 would be way too small. I don't know anything about the capabilities of such a rocket, I assume 100t LEO should be easily achievable.

checkout @modemeagle's performance simulation of FH with 6 booster cores with various cross-feeding schemes minus upper stage.
link (http://forum.nasaspaceflight.com/index.php?topic=29214.msg967267#msg967267)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MATTBLAK on 12/09/2014 08:29 pm
A five core version with a LOX/CH4 upper stage should give the same performance as Block 1 SLS for lower cost. A fully cryogenic upper stage, even more so.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: groundbound on 12/09/2014 09:11 pm
regarding this "we don't know yet": so far we know, that elon musk has a very ambitious plan regarding mars. and I sometimes think: what needs to be done, if something is a showstopper in the raptor-development. as far as we know, building such large rocket engines and rockets (like BFR) is quite something difficult.

so assuming, they can't do BFR (would be a sad thing),


IMO if it is not BFR it is still likely to be a much larger step than F9 -> F9 1.1 -> FH -> FH+crossfeed. A large part of the smallness of those incremental steps is driven by a desire to divert most design resources towards BFR.

My point of "we don't know yet" aligns with the frequent speculation here that FH may simply not have that many flights over its lifetime. I agree with the speculation that as BFR comes online it may obsolete FH long before anyone talks about retiring F9. So if the window between FH first flight and BFR shrinks, that really dooms any desire to work on FH. Alternatively, if that time window grows, then other things than crossfeed might also look worthwhile.

But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 12/09/2014 10:04 pm
Without cross-feed, F9H boosters should go as high as F9 first stage, right?

Strap-on cores will be depleted early, with or without crossfeed. The center core would throttle down shortly after liftoff to conserve propellant la Delta IV Heavy.
FH boosters have more propellant than the core. Doing some back of the envelop calculations, I got that throttling center down to 70% at maxq would mean that boosters and core deplete at the same time.
SpaceX could throttle the core much more than that. They have 9 engines on there, so they can shut some of them down like they used to for v1.0. And heck, they could shut nearly all of them down and restart them (if they felt lucky). Shutting down engines then restarting them gives you a higher Isp than throttling all the engines (because throttling reduces the chamber pressure), but there are reasons why you wouldn't necessarily want to do it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 12/10/2014 02:04 am
regarding this "we don't know yet": so far we know, that elon musk has a very ambitious plan regarding mars. and I sometimes think: what needs to be done, if something is a showstopper in the raptor-development. as far as we know, building such large rocket engines and rockets (like BFR) is quite something difficult.

so assuming, they can't do BFR (would be a sad thing),


IMO if it is not BFR it is still likely to be a much larger step than F9 -> F9 1.1 -> FH -> FH+crossfeed. A large part of the smallness of those incremental steps is driven by a desire to divert most design resources towards BFR.

My point of "we don't know yet" aligns with the frequent speculation here that FH may simply not have that many flights over its lifetime. I agree with the speculation that as BFR comes online it may obsolete FH long before anyone talks about retiring F9. So if the window between FH first flight and BFR shrinks, that really dooms any desire to work on FH. Alternatively, if that time window grows, then other things than crossfeed might also look worthwhile.

But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.


I'm not sure what you mean by desire to divert design resources to BFR.  I doubt there is a single engineer assigned to work just on BFR.  BFR is likely water cooler conversation and what if discussions at this point. It is a long way off.

I'm not sure where you are picking up on the idea of not many FH flights either.  If anything it seems that a reuseable FH gets more flights to avoid expendable F9's. 

Not to be hard on anyone's dreams, the BFR is a cool idea, but if SpaceX can't get something as easy as a 3 core, 27 engine Reuseable FH to work, then going to Mars is not going to happen.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 12/10/2014 02:30 am
regarding this "we don't know yet": so far we know, that elon musk has a very ambitious plan regarding mars. and I sometimes think: what needs to be done, if something is a showstopper in the raptor-development. as far as we know, building such large rocket engines and rockets (like BFR) is quite something difficult.

so assuming, they can't do BFR (would be a sad thing),


IMO if it is not BFR it is still likely to be a much larger step than F9 -> F9 1.1 -> FH -> FH+crossfeed. A large part of the smallness of those incremental steps is driven by a desire to divert most design resources towards BFR.

My point of "we don't know yet" aligns with the frequent speculation here that FH may simply not have that many flights over its lifetime. I agree with the speculation that as BFR comes online it may obsolete FH long before anyone talks about retiring F9. So if the window between FH first flight and BFR shrinks, that really dooms any desire to work on FH. Alternatively, if that time window grows, then other things than crossfeed might also look worthwhile.

But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.


I'm not sure what you mean by desire to divert design resources to BFR.  I doubt there is a single engineer assigned to work just on BFR.  BFR is likely water cooler conversation and what if discussions at this point. It is a long way off.

I'm not sure where you are picking up on the idea of not many FH flights either.  If anything it seems that a reuseable FH gets more flights to avoid expendable F9's. 

Not to be hard on anyone's dreams, the BFR is a cool idea, but if SpaceX can't get something as easy as a 3 core, 27 engine Reuseable FH to work, then going to Mars is not going to happen.

If they can launch 8 F9v1.1s flawlessly*, its a pretty safe bet they can launch a FH.

There may be nobody working exclusively on BFR specifically at the moment, but there is absolutely work going on designing and testing the Raptor engine, which is the long pole in BFR development.

FH is almost (in rocket timescales) ready to launch at this point with multiple flights sold, so there's no sense doubting it. I'm sure SpaceX plans on selling many (dozens, perhaps) flights of the FH for 5+ ton GEO satellites in the years before the BFR is operational. They almost certainly won't need anything with higher performance than crossfeed offers, even with the side boosters doing RTLS.


*the launch campaigns may not have been literally perfect, but the payloads were all delivered successfully with no customer complaints.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 12/10/2014 03:38 am

I'm not sure what you mean by desire to divert design resources to BFR.  I doubt there is a single engineer assigned to work just on BFR.  BFR is likely water cooler conversation and what if discussions at this point. It is a long way off.

I totally doubt that, there must be several working on various aspects of the Raptor at this instance, and if there are, there must be a few concerned with how it connects to the rest of the BFR
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: robert_d on 12/10/2014 04:01 am

...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 12/10/2014 04:59 am

...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?

Well if pad LC-39B become available in the future. It could easily be reconfigured to the new pad LC-39A design. Then you can do a dual FH launch from Kennedy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 12/10/2014 05:18 am

...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?

Well if pad LC-39B become available in the future. It could easily be reconfigured to the new pad LC-39A design. Then you can do a dual FH launch from Kennedy.

And recover 6 separate cores that close together? I think that would put a serious strain on capabilities for the next couple of years
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MATTBLAK on 12/10/2014 05:59 am

...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?

Well if pad LC-39B become available in the future. It could easily be reconfigured to the new pad LC-39A design. Then you can do a dual FH launch from Kennedy.

Dual Falcon Heavy launches plus 1x Delta IV-H (or new ULA booster) with on-orbit assembly would get enough mass up there for a decent lunar mission. For a Phobos/Deimos mission: add the Texas FH launch site for a salvo-launch of the same, but then rinse-pads-and-repeat... ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 12/10/2014 07:55 am
FH is almost (in rocket timescales) ready to launch at this point with multiple flights sold, so there's no sense doubting it. I'm sure SpaceX plans on selling many (dozens, perhaps) flights of the FH for 5+ ton GEO satellites in the years before the BFR is operational. They almost certainly won't need anything with higher performance than crossfeed offers, even with the side boosters doing RTLS.

F9-R is limited to 3.5 tons, and even that size will need FH-R if the operator wants 1500 m/s instead of 1800 m/s to GEO.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 12/10/2014 12:06 pm
If they can launch 8 F9v1.1s flawlessly*, its a pretty safe bet they can launch a FH.

There may be nobody working exclusively on BFR specifically at the moment, but there is absolutely work going on designing and testing the Raptor engine, which is the long pole in BFR development.

FH is almost (in rocket timescales) ready to launch at this point with multiple flights sold, so there's no sense doubting it. I'm sure SpaceX plans on selling many (dozens, perhaps) flights of the FH for 5+ ton GEO satellites in the years before the BFR is operational. They almost certainly won't need anything with higher performance than crossfeed offers, even with the side boosters doing RTLS.


*the launch campaigns may not have been literally perfect, but the payloads were all delivered successfully with no customer complaints.

FH is a big step from F9.    It's December 2014 and we haven't seen hardware leave the factory or get tested in Texas.  SpaceX has a long way to go and if you asked people working on the hardware I'm sure they wouldn't say it's almost done.  The thousands of details when you get closer to the end of a project become more active.

I appreciate your enthusiasm but nothing in rockets can be taken for granted or seen as 'almost ready to fly' until it actually flies.

Also, Raptor is not BFR.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 12/10/2014 02:03 pm

I'm not sure what you mean by desire to divert design resources to BFR.  I doubt there is a single engineer assigned to work just on BFR.  BFR is likely water cooler conversation and what if discussions at this point. It is a long way off.

I totally doubt that, there must be several working on various aspects of the Raptor at this instance, and if there are, there must be a few concerned with how it connects to the rest of the BFR

This was what I wrote, you attributed what Owlon wrote to me. Raptor has no use before BFR so any engineering devoted to connecting it to tanks and structure are per se work on BFR.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/10/2014 02:52 pm

...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?
Unless the Cape launched FH does a dogleg, or range allows for a Florida overflight, Boca Chica can only launch to a 26.5 inclination while Cape can do 28.5-55. Since LEO doglegs are expensive, I don't see it quite possible. If there was the requirement, probably the cheapest solution would be to do an LC-40B pad for the FH. Probably a 35M investment without the Integration Tower.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/10/2014 03:00 pm
Without cross-feed, F9H boosters should go as high as F9 first stage, right?

Strap-on cores will be depleted early, with or without crossfeed. The center core would throttle down shortly after liftoff to conserve propellant la Delta IV Heavy.
FH boosters have more propellant than the core. Doing some back of the envelop calculations, I got that throttling center down to 70% at maxq would mean that boosters and core deplete at the same time.
SpaceX could throttle the core much more than that. They have 9 engines on there, so they can shut some of them down like they used to for v1.0. And heck, they could shut nearly all of them down and restart them (if they felt lucky). Shutting down engines then restarting them gives you a higher Isp than throttling all the engines (because throttling reduces the chamber pressure), but there are reasons why you wouldn't necessarily want to do it.
I don't believe that if we are discussing not using cross feed to reduce risks, shutting down and relighting engines on the core would be quite an option. After all, the idea of throttling down is to conserve propellant and limit booster burnout acceleration. But you probably want to go as fast of possible after staging.
That said, Elon did stated something that could be interpreted as an actual 60% throttle for the Merlin 1D. I think he actually stated it could throttle down 40% on twitter. Doing 50% was an EELV requirement, so both RD-180 and RS-68 can do it. And I believe RD-191 can do 30%. So doing 60% on the Merlin 1D seems quite doable. But 40% seems more like a stretch. In fact, 60% seems right the the lowest point of when Tom Muller stated during development that Merlin 1D would be able to do 70%, but the thrust was later increased. So 60% could very well be right that same original design point.
In other words, disregarding the isp, the core could probably do 60% without shutting anything down and then have a slightly longer burn time than the boosters.
But from a mission assurance point of view, I'd rather shutdown everything, stage second stage, and only then separate the boosters and initiate the RTLS maneuver. If you don't need the marginal extra performance, which is probably under 5% (without cross feeding), I'd rather put all the risk on the recovering of the stages and not on the success of the mission.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: wannamoonbase on 12/10/2014 04:05 pm

I'm not sure what you mean by desire to divert design resources to BFR.  I doubt there is a single engineer assigned to work just on BFR.  BFR is likely water cooler conversation and what if discussions at this point. It is a long way off.

I totally doubt that, there must be several working on various aspects of the Raptor at this instance, and if there are, there must be a few concerned with how it connects to the rest of the BFR

This was what I wrote, you attributed what Owlon wrote to me. Raptor has no use before BFR so any engineering devoted to connecting it to tanks and structure are per se work on BFR.

My apologies on attributing incorrectly.

I still disagree with assigning Raptor to BFR, but we can agree to disagree.  I think a F9 and FH replacement is a likely first step.  It would generate revenue from commercial customers and provide flight history.   Also, if Raptor achieves 1.7 million pounds thrust it will have improved performance over F9, FH.

The 3 core configuration of FH and crossfeed can benefit any future vehicle that SpaceX decides to develop.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 12/10/2014 05:44 pm
that would be a nice and interesting rocket.

by replacing 9 merlin 1d engines with 1 raptor (and of course the tank with a methalox-capable system), they could produce an interesting heavy-hybrid-rocket.

for example a falcon raptor 1, roughly the same size as the F9, but with one raptor engine. no rescue-capability, if the engine dies, the mission fails, and no reusability.

a falcon raptor heavy with 2 raptor booster stages + the central raptor stage. again, no rescue-capabilty and no reusability.

more or less they are the falcon X and falcon X heavy versions which already float around, but with raptors instead of the proposed merlin 2 engines.

a hybrid with falcon heavy boosters and a central raptor stage. okay, crossfeed is gone, the raptor can't use kerosene. but it could act as an inflight-testbed for raptor flights. it might be a bit stronger than a falcon heavy with crossfeed. booster stages can encounter engine failures without losing the mission, the central stage has to survive. the booster stages can be recovered.

I could be wrong, but an advantage is (in my eyes) that one engine is cheaper than 9 engines. maybe it's 2-4x more expensive than a merlin, but it works like 10 merlins.

regarding recovery a question: does the falcon 9 first stage need all 3 engines to land, or is it capable of landing with 2 engines. if so, the central raptor stage could carry additional 2 stages with additional kerosene with it, so it can land propulsively. I know, that adds a lot of complexity, having 2 different types of fuel on board, but it could save that stage. I know that it is hardly likely that they will produce such a rocket. I'm just thinking out of the box.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 12/10/2014 06:15 pm
If they can launch 8 F9v1.1s flawlessly*, its a pretty safe bet they can launch a FH.

There may be nobody working exclusively on BFR specifically at the moment, but there is absolutely work going on designing and testing the Raptor engine, which is the long pole in BFR development.

FH is almost (in rocket timescales) ready to launch at this point with multiple flights sold, so there's no sense doubting it. I'm sure SpaceX plans on selling many (dozens, perhaps) flights of the FH for 5+ ton GEO satellites in the years before the BFR is operational. They almost certainly won't need anything with higher performance than crossfeed offers, even with the side boosters doing RTLS.


*the launch campaigns may not have been literally perfect, but the payloads were all delivered successfully with no customer complaints.

FH is a big step from F9.    It's December 2014 and we haven't seen hardware leave the factory or get tested in Texas.  SpaceX has a long way to go and if you asked people working on the hardware I'm sure they wouldn't say it's almost done.  The thousands of details when you get closer to the end of a project become more active.

I appreciate your enthusiasm but nothing in rockets can be taken for granted or seen as 'almost ready to fly' until it actually flies.

Also, Raptor is not BFR.

I don't mean to hand wave away the extensive engineering work that FH involves, I just mean to say that a current launch goal of mid to late-2015 means most of that must be already done. Just because we haven't seen hardware doesn't mean it doesn't exist. It seems very realistic to me that FH will fly in 2015, which I would describe as "almost ready." I don't deny that there may be substantial delays, but it seems to me that most of those have probably already happened; I guess we'll know in another 6-12 months.

Raptor is not BFR, but Raptor is being designed explicitly and probably exclusively for use on the BFR, ergo for all intents and purposes Raptor work is BFR work.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 12/10/2014 06:23 pm

I'm not sure what you mean by desire to divert design resources to BFR.  I doubt there is a single engineer assigned to work just on BFR.  BFR is likely water cooler conversation and what if discussions at this point. It is a long way off.

I totally doubt that, there must be several working on various aspects of the Raptor at this instance, and if there are, there must be a few concerned with how it connects to the rest of the BFR

This was what I wrote, you attributed what Owlon wrote to me. Raptor has no use before BFR so any engineering devoted to connecting it to tanks and structure are per se work on BFR.

My apologies on attributing incorrectly.

I still disagree with assigning Raptor to BFR, but we can agree to disagree.  I think a F9 and FH replacement is a likely first step.  It would generate revenue from commercial customers and provide flight history.   Also, if Raptor achieves 1.7 million pounds thrust it will have improved performance over F9, FH.

The 3 core configuration of FH and crossfeed can benefit any future vehicle that SpaceX decides to develop.

Sorry, but I am under the impression that what we used to refer to as the Falcon X is now the BFR and the XX is the MCT.  Using the raptor and currently suggested thrust is in the Falcon X class for a single engine single core. Fitting a Raptor to an F9 seems to me to be either overkill and potentially reduction in performance based on wasted engine weight, to scale the F9 core up to the weight that makes sense using a Raptor with, the core needs to be of larger diameter because if you just add length you are going more than 50% more given the lower total propellant density. I don't think the F9 core can be stretched another 50%.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 12/10/2014 06:32 pm
I could be wrong, but an advantage is (in my eyes) that one engine is cheaper than 9 engines. maybe it's 2-4x more expensive than a merlin, but it works like 10 merlins.

I think you are definitely wrong. Do you really think that an engine that is 10x is powerful will only cost 2-4x? Keep in mind that the smaller engines benefit from an order of magnitude increased mass production.

But that is just for expendable mode - If factor in that you cannot re-use the stage (and the 10 engines), then you are going to throw away the Raptor instead of getting extra uses from the Merlins, which will lower their effective cost even further.

No, that sounds a lot more like wishful thinking than reality.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: robert_d on 12/10/2014 11:23 pm

...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?
Unless the Cape launched FH does a dogleg, or range allows for a Florida overflight, Boca Chica can only launch to a 26.5 inclination while Cape can do 28.5-55. Since LEO doglegs are expensive, I don't see it quite possible. If there was the requirement, probably the cheapest solution would be to do an LC-40B pad for the FH. Probably a 35M investment without the Integration Tower.

Thanks for that. I don't quite remember from the Texas launch site thread was there a problem with 28 degrees south? Does it over fly Yucatan?
 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 12/10/2014 11:42 pm
Yes it is a very narrow path they can launch along, however, a 2 degree plane change at LEO is roughly 280m/s
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/10/2014 11:45 pm


...But try to integrate lots of boosters? Call me skeptical. High energy upper stage and/or orbital refueling would seem far more worth a long term payoff.

Would it be possible to same-day-launch 2 Falcon heavies into the same orbital plane, one from Florida and then one from Texas at the proper time for alignment?
Unless the Cape launched FH does a dogleg, or range allows for a Florida overflight, Boca Chica can only launch to a 26.5 inclination while Cape can do 28.5-55. Since LEO doglegs are expensive, I don't see it quite possible. If there was the requirement, probably the cheapest solution would be to do an LC-40B pad for the FH. Probably a 35M investment without the Integration Tower.

Thanks for that. I don't quite remember from the Texas launch site thread was there a problem with 28 degrees south? Does it over fly Yucatan?
Yucatan was for southward 51.7 (ISS), but then you have Colombia, Venezuela, Guyana, Cayenne, French Guiana and Brazil to worry about, plus a lot of Caribbean island, specially counting Cuba. Think about drop zones and failure risk.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 12/10/2014 11:50 pm
If Texas is limited to 26.5 and the Cape to 28.5 (for direct flight), then split the difference and fly to 27.5. Doesn't take THAT much delta-v to do a 1 degree change.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/11/2014 12:07 am
If Texas is limited to 26.5 and the Cape to 28.5 (for direct flight), then split the difference and fly to 27.5. Doesn't take THAT much delta-v to do a 1 degree change.
Boca Chica limitation is so late that the vehicle will almost be orbital. It would probably require a dogleg of 2deg from the Cape. I wonder how much performance would it lose. Pure circular plane change of circular LEO is about 275m/s. That's the different between LEO and what?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: nadreck on 12/11/2014 01:30 am
If Texas is limited to 26.5 and the Cape to 28.5 (for direct flight), then split the difference and fly to 27.5. Doesn't take THAT much delta-v to do a 1 degree change.
Boca Chica limitation is so late that the vehicle will almost be orbital. It would probably require a dogleg of 2deg from the Cape. I wonder how much performance would it lose. Pure circular plane change of circular LEO is about 530m/s. That's the different between LEO and what?

My plane change ROT for LEO is 140m/s per degree you seem to be near double that
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/11/2014 02:14 pm
If Texas is limited to 26.5 and the Cape to 28.5 (for direct flight), then split the difference and fly to 27.5. Doesn't take THAT much delta-v to do a 1 degree change.
Boca Chica limitation is so late that the vehicle will almost be orbital. It would probably require a dogleg of 2deg from the Cape. I wonder how much performance would it lose. Pure circular plane change of circular LEO is about 530m/s. That's the different between LEO and what?

My plane change ROT for LEO is 140m/s per degree you seem to be near double that
It's not the first nor last time I make mistakes ;-) I've corrected my post.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/11/2014 03:02 pm
Doing a silly approximation (namely, calculating a LEO at 686km which has 272m/s extra than 200km circular), I get a 10% loss for a Falcon 9 v1.1 from the Cape. At least according to NASA's NLS II site.
So, if the non cross feed Falcon Heavy had something like 45tonnes to LEO, then you could have a 45 tonnes launch from Boca Chica and a 40 tonnes launch from the Cape. For a very respectable 85 tonnes net launch withing a few hours. I believe it could enable some serious mission profiles. And if you added an LC-40B launch pad, you could have 125tonnes also in short order. If you assume 53 you could get 145tonnes with those three launches. Regrettably, doing RV and docking is complicated and the launch schedule reliability of 86 engines is something to think about.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 12/11/2014 05:37 pm
If Texas is limited to 26.5 and the Cape to 28.5 (for direct flight), then split the difference and fly to 27.5. Doesn't take THAT much delta-v to do a 1 degree change.

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 12/11/2014 05:50 pm

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.

28.5 is the lowest you can get from the Cape.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 12/11/2014 06:09 pm

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.

28.5 is the lowest you can get from the Cape.

Do'h, of course. For some reason I thought Boca Chica would launch more southwards (inclination higher than 28.5), but I guess they will launch pretty much straight eastward.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: robert_d on 12/11/2014 06:12 pm

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.

28.5 is the lowest you can get from the Cape.

This is absolutely TRUE - it is why the Russians must fly the high inclinations out of Baikonur. But for Jim or anyone is there a good short explanation somewhere as to why? I always picture in my head that the spacecraft has to complete a great circle around the globe to be in orbit - so any lower inclination than your latitude will mean you are actually boosting away from earth's center. But this is a certainly an incomplete and likely confused assumption.   
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: baldusi on 12/11/2014 07:22 pm

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.

28.5 is the lowest you can get from the Cape.

This is absolutely TRUE - it is why the Russians must fly the high inclinations out of Baikonur. But for Jim or anyone is there a good short explanation somewhere as to why? I always picture in my head that the spacecraft has to complete a great circle around the globe to be in orbit - so any lower inclination than your latitude will mean you are actually boosting away from earth's center. But this is a certainly an incomplete and likely confused assumption.
if you can picture the projection of an orbit on a map, you can clearly see that if you launch exactly with an Eastward (or Westward for retrograde) the orbit will then pass the thought the equator and thus you'll be launching from its maximum latitude, hence the inclination. On the other hand, if you launch with any inclination, you will have some part of the race track above your latitude, and thus the orbit will be more inclined.
If you want to think it otherwise, think of an equatorial orbit. Its a line over the equator. If you can't get there from anywhere not on the equator without some maneuver. On the other hand think of a polar orbit. You just have to wait for the Earth to rotate and that's it.
What the Cape cant do, is lower than 28.5 deg without a dogleg maneuver. You can probably get to the 26.5 orbit, but you will lose performance since the rocket needs to go south and then turn estward. As I said above, I guessed somewhere between 10% and 15% payload loss for a 200km LEO.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: robert_d on 12/11/2014 10:54 pm


Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.

28.5 is the lowest you can get from the Cape.

This is absolutely TRUE - it is why the Russians must fly the high inclinations out of Baikonur. But for Jim or anyone is there a good short explanation somewhere as to why? I always picture in my head that the spacecraft has to complete a great circle around the globe to be in orbit - so any lower inclination than your latitude will mean you are actually boosting away from earth's center. But this is a certainly an incomplete and likely confused assumption.
if you can picture the projection of an orbit on a map, you can clearly see that if you launch exactly with an Eastward (or Westward for retrograde) the orbit will then pass the thought the equator and thus you'll be launching from its maximum latitude, hence the inclination. On the other hand, if you launch with any inclination, you will have some part of the race track above your latitude, and thus the orbit will be more inclined.
If you want to think it otherwise, think of an equatorial orbit. Its a line over the equator. If you can't get there from anywhere not on the equator without some maneuver. On the other hand think of a polar orbit. You just have to wait for the Earth to rotate and that's it.
What the Cape cant do, is lower than 28.5 deg without a dogleg maneuver. You can probably get to the 26.5 orbit, but you will lose performance since the rocket needs to go south and then turn westward. As I said above, I guessed somewhere between 10% and 15% payload loss for a 200km LEO.
Thanks for trying, but in order to not to derail this thread, I will move to the Q&A threads to try to get additional responses, as to WHY the geometry limits inclination.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 12/12/2014 03:20 am

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.

28.5 is the lowest you can get from the Cape.
...directly. Can always do a plane change later in the trajectory, it's just expensive. But a degree or two isn't too bad.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 12/26/2014 02:10 am
A five core version with a LOX/CH4 upper stage should give the same performance as Block 1 SLS for lower cost. A fully cryogenic upper stage, even more so.

I like the idea of a five core Falcon Very Heavy, Angara style... The three core version can do 53 mt to LEO.
But there might a few problems like infrastructure and testing. Wonder how much it could put in LEO or to the Moon.
I would keep the same upper stage for cost and simplicity.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Owlon on 12/26/2014 04:13 am
A five core version with a LOX/CH4 upper stage should give the same performance as Block 1 SLS for lower cost. A fully cryogenic upper stage, even more so.

I like the idea of a five core Falcon Very Heavy, Angara style... The three core version can do 53 mt to LEO.
But there might a few problems like infrastructure and testing. Wonder how much it could put in LEO or to the Moon.
I would keep the same upper stage for cost and simplicity.

A stretched upper stage could improve FH performance a lot and would probably be a much simpler option than adding another two cores--also much cheaper per launch.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: TomH on 12/26/2014 04:31 am
You can probably get to the 26.5 orbit, but you will lose performance since the rocket needs to go south and then turn westward.

Eastward. Turn westward and you're really going to lose performance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sghill on 12/26/2014 12:00 pm

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.
E
28.5 is the lowest you can get from the Cape.

Because of the Bahamas?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: fast on 12/26/2014 12:29 pm
A five core version with a LOX/CH4 upper stage should give the same performance as Block 1 SLS for lower cost. A fully cryogenic upper stage, even more so.

I like the idea of a five core Falcon Very Heavy, Angara style... The three core version can do 53 mt to LEO.
But there might a few problems like infrastructure and testing. Wonder how much it could put in LEO or to the Moon.
I would keep the same upper stage for cost and simplicity.

A stretched upper stage could improve FH performance a lot and would probably be a much simpler option than adding another two cores--also much cheaper per launch.

True, following mass distribution between first and second stage of F9, FH should have from 2 to 3 times more fuel in second stage than in F9 second stage. Because it virtually have 3 first stages in parallel.
They still can keep only one merlin on second stage, FH have so much excess thrust in core stage that it will throw second stage so high that little altitude drop during second stage burn will not harm performance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: douglas100 on 12/26/2014 01:11 pm

Am I missing something here? Why not just fly to 26.5 from the Cape as well? Texas has the launch azimuth limitation, the Cape doesn't.
E
28.5 is the lowest you can get from the Cape.

Because of the Bahamas?


No, because of latitude. The lowest inclination you can get from any launch site (without dog legging) is equal to its latitude. The launch azimuth for this is always due east.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 12/26/2014 02:33 pm
A five core version with a LOX/CH4 upper stage should give the same performance as Block 1 SLS for lower cost. A fully cryogenic upper stage, even more so.

I like the idea of a five core Falcon Very Heavy, Angara style... The three core version can do 53 mt to LEO.
But there might a few problems like infrastructure and testing. Wonder how much it could put in LEO or to the Moon.
I would keep the same upper stage for cost and simplicity.

A stretched upper stage could improve FH performance a lot and would probably be a much simpler option than adding another two cores--also much cheaper per launch.

True, following mass distribution between first and second stage of F9, FH should have from 2 to 3 times more fuel in second stage than in F9 second stage. Because it virtually have 3 first stages in parallel.
They still can keep only one merlin on second stage, FH have so much excess thrust in core stage that it will throw second stage so high that little altitude drop during second stage burn will not harm performance.

I thought that the F9 upper stage was already designed with the Falcon Heavy in mind and that it for the F9 is not fully tanked. (i read that somewhere but i do not recall where and i might be wrong)
To stretch the upper stage is a good idea for a 5 core configuration....
It might get close to SLS performance for a fraction of the price
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lar on 12/26/2014 02:44 pm
Stretching the upper stage will require changes to ground support equipment so there's speculation that there has been reluctance to do this.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 12/26/2014 03:53 pm

Not to mention the thermal energy of 45 Merlin's blasting of that poor launchpad...  ;)

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 12/26/2014 11:30 pm

Not to mention the thermal energy of 45 Merlin's blasting of that poor launchpad...  ;)

Bah. So what about the output from the 9 Raptors on the bottom of the BFR (as envisage from the latest rumors)?  :P

The output from from 45 Merlin engines is about 29.4 mN. As compare to 9 Raptor engines at about 62.1 mN.  :o

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: whitelancer64 on 12/27/2014 12:09 am

I thought that the F9 upper stage was already designed with the Falcon Heavy in mind and that it for the F9 is not fully tanked. (i read that somewhere but i do not recall where and i might be wrong)
To stretch the upper stage is a good idea for a 5 core configuration....
It might get close to SLS performance for a fraction of the price

Stretching the upper stage will require changes to ground support equipment so there's speculation that there has been reluctance to do this.

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 12/27/2014 08:26 am
Quote
I thought that the F9 upper stage was already designed with the Falcon Heavy in mind and that it for the F9 is not fully tanked. (i read that somewhere but i do not recall where and i might be wrong)
To stretch the upper stage is a good idea for a 5 core configuration....
It might get close to SLS performance for a fraction of the price
I had thought that at one point.

Commentary during several launch broadcasts proved that to be wrong.

Cheers, Martin

Edit: fixed quotes.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Coastal Ron on 12/27/2014 03:25 pm
I thought that the F9 upper stage was already designed with the Falcon Heavy in mind and that it for the F9 is not fully tanked. (i read that somewhere but i do not recall where and i might be wrong)
To stretch the upper stage is a good idea for a 5 core configuration....
It might get close to SLS performance for a fraction of the price

SpaceX doesn't need a 5-core Falcon Heavy since they are building their BFR.  And I would suspect that they would have to redesign quite a lot of the Falcon core sections in order to make it possible to attach four cores to one central core, not to mention the major changes that would be needed for the assembly building, Transporter Erector and launch pad configuration.  That's a lot of work for a configuration that would still be too small for their ultimate needs (i.e. lifting hardware bound for Mars).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 12/27/2014 10:43 pm

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: HMXHMX on 12/29/2014 04:42 am

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?

It's "fineness," as in "fineness ratio."  Von Braun once told a friend of mine who was a vehicle designer at JSC that one should never build a rocket with a fineness ratio greater than 10:1.  My friend related this story to me five years ago as a commentary on Ares 1.

To the question, however the principal advantage of a long slender configuration will be reduced drag, and secondarily increased head pressure for the pump inlet to forestall start-up cavitation.  In my view these features are offset by the structural and control uncertainties, especially in the face of winds aloft.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: whitelancer64 on 12/29/2014 05:37 am

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?

i'm sorry, yes, it is "fineness" ... "fitness" was a typo on my part. there's not much out there on "fineness ratio" for rockets, it's a specific part of rocket design related to the friction drag coefficients. i'm not sure where i heard that the ideal ratio for a rocket is about 14-15 to 1 (now that i've had a minute to think about it, i think it was something i heard ages ago, on the rockets episode of Scrapheap Challenge), but it's something that's stuck in my head.

there's a short version (a thesis paper on the aerodynamic properties of model rockets in flight simulations) here: http://openrocket.sourceforge.net/techdoc.pdf (http://openrocket.sourceforge.net/techdoc.pdf)

and a more complicated version (a really neat declassified document from 1947) here: http://www.governmentattic.org/RAND/RA-15022.pdf (http://www.governmentattic.org/RAND/RA-15022.pdf)

however, my point is that while high fineness ratios are great for reducing drag, the longer and skinnier something is, the easier it is to bend it. as a good example (that's also seasonally relevant), think of a long, skinny wrapping paper tube - really easy to bend, and that's not such a good thing for a 224 foot tall rocket. airplanes (and other long, skinny things like ships and skyscrapers) can get away with very high fineness ratios because they have a lot more internal structural reinforcement than rockets do.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lars-J on 12/30/2014 01:42 am

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?

It's "fineness," as in "fineness ratio."  Von Braun once told a friend of mine who was a vehicle designer at JSC that one should never build a rocket with a fineness ratio greater than 10:1.  My friend related this story to me five years ago as a commentary on Ares 1.

Yes, but I was hoping for something more authoritative than "Von Braun [once said] that one should never build a rocket with a fineness ratio greater than 10:1". Why? What was his reasoning? What tests had been done?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: BobHk on 12/30/2014 03:21 am

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?

It's "fineness," as in "fineness ratio."  Von Braun once told a friend of mine who was a vehicle designer at JSC that one should never build a rocket with a fineness ratio greater than 10:1.  My friend related this story to me five years ago as a commentary on Ares 1.

To the question, however the principal advantage of a long slender configuration will be reduced drag, and secondarily increased head pressure for the pump inlet to forestall start-up cavitation.  In my view these features are offset by the structural and control uncertainties, especially in the face of winds aloft.

Aren't the Falcons also built this size to allow them to be driven around on highways?  Its a logistical advantage versus wider rockets.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 12/30/2014 04:20 am

Aren't the Falcons also built this size to allow them to be driven around on highways?  Its a logistical advantage versus wider rockets.

Yes, there were statements to that effect. The diameter was chosen to make the stage road transportable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Comga on 12/30/2014 05:16 am

Aren't the Falcons also built this size to allow them to be driven around on highways?  Its a logistical advantage versus wider rockets.

Yes, there were statements to that effect. The diameter was chosen to make the stage road transportable.

Which brings us back, dum-ta-ta-dum, to the Falcon Heavy.
Because the combination of the diameter limit for making the Falcon road-transportable, and the limit on fineness, the length to diameter ratio, puts an overall size limit on the Falcon 9. 
The way to get beyond this is....
to stack them side-by-side!
Hence the Falcon Heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: HMXHMX on 12/30/2014 03:41 pm

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?

It's "fineness," as in "fineness ratio."  Von Braun once told a friend of mine who was a vehicle designer at JSC that one should never build a rocket with a fineness ratio greater than 10:1.  My friend related this story to me five years ago as a commentary on Ares 1.

To the question, however the principal advantage of a long slender configuration will be reduced drag, and secondarily increased head pressure for the pump inlet to forestall start-up cavitation.  In my view these features are offset by the structural and control uncertainties, especially in the face of winds aloft.

Aren't the Falcons also built this size to allow them to be driven around on highways?  Its a logistical advantage versus wider rockets.

A minor one, in my view.  SpaceX grew it's current vehicle infrastructure by a process of accretion of existing surplus facilities.  Co-location of manufacturing, test and launch is obviously preferable and is probably what we are likely to see with future "BFR" launch vehicles from SpaceX.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: HMXHMX on 12/30/2014 03:45 pm

a bigger problem is structural weakness. the Falcon 9 v1.1 is a very long and skinny rocket as it is. the ideal fitness ratio (length / diameter) for a rocket is about 14-15 to 1 and the Falcon 9 has a fitness ratio of about 18 to 1. there's not a lot of margin before it becomes very easy to bend the rocket.

What is the source for the ideal rocket "fitness"? Can you point to a paper weighing the pros and cons?

It's "fineness," as in "fineness ratio."  Von Braun once told a friend of mine who was a vehicle designer at JSC that one should never build a rocket with a fineness ratio greater than 10:1.  My friend related this story to me five years ago as a commentary on Ares 1.

Yes, but I was hoping for something more authoritative than "Von Braun [once said] that one should never build a rocket with a fineness ratio greater than 10:1". Why? What was his reasoning? What tests had been done?

Sorry.  Don't know.  But there is such a thing as "engineering intuition" and von Braun had it, even though I argued with him over his intuition once (actually related to commercial vs. gov't launch programs...in 1972).  There have been many, many trades done over the years and I guess you just have to look at where most LV designers start their designs to get a feeling for how those trades played out.

Edit: spelling

Clarification: I was referring to not knowing what prompted von Braun's comment, not not knowing why one would wish to avoid long thin rockets…that has been already discussed.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Kabloona on 12/30/2014 05:18 pm
On the subject of fineness ratio...the original Taurus rocket was so "bendy" as a result of stacking a Pegasus rocket atop a Peacekeeper that the designers had to incorporate active control of the first bending moment into the guidance algorithm for the Stage 0 TVC.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 12/30/2014 10:25 pm
Since the FH booster cores got stretch propellant tanks. Could anyone hazard a guess to the performance of a FH booster core with a upper stage in the mono-core LV role?

Leaving aside that you will need a new TEL or modified the current TELs..
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 12/31/2014 04:06 am
Since the FH booster cores got stretch propellant tanks. Could anyone hazard a guess to the performance of a FH booster core with a upper stage in the mono-core LV role?


Yes. A beautiful fireball around maxQ. That booster is not built to withstand that load with payload on.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 12/31/2014 11:54 am


Since the FH booster cores got stretch propellant tanks. Could anyone hazard a guess to the performance of a FH booster core with a upper stage in the mono-core LV role?

Yes. A beautiful fireball around maxQ. That booster is not built to withstand that load with payload on.

Agreed, that's how it achieves its mass ratio.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 01/01/2015 01:08 am
On the subject of fineness ratio...the original Taurus rocket was so "bendy" as a result of stacking a Pegasus rocket atop a Peacekeeper that the designers had to incorporate active control of the first bending moment into the guidance algorithm for the Stage 0 TVC.
Makes you wonder if Falcon might not be doing active control of bending moments as well. The SpaceX guidance guys seem top-notch, and a few more terms in a control equation are not a problem for modern computers (which is to say: the formidable difficulties lie in simulation, validation, tuning, etc, not in flying the equations).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 01/01/2015 02:32 am
I thought that the F9 upper stage was already designed with the Falcon Heavy in mind and that it for the F9 is not fully tanked. (i read that somewhere but i do not recall where and i might be wrong)
To stretch the upper stage is a good idea for a 5 core configuration....
It might get close to SLS performance for a fraction of the price

SpaceX doesn't need a 5-core Falcon Heavy since they are building their BFR.  And I would suspect that they would have to redesign quite a lot of the Falcon core sections in order to make it possible to attach four cores to one central core, not to mention the major changes that would be needed for the assembly building, Transporter Erector and launch pad configuration.  That's a lot of work for a configuration that would still be too small for their ultimate needs (i.e. lifting hardware bound for Mars).

The booster cores are already redesigned to have a high massratio. Maybe the centercore too, to make it stronger. That assembly building looks big enough, the transporter erector needs a bit of work. so it might be possible. I agree with you that they don't need and it is too small for their ultimate needs (people and hardware for Mars). For that you need a 5 core BFR   ;)

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Zed_Noir on 01/01/2015 05:55 am

...

I agree with you that they don't need and it is too small for their ultimate needs (people and hardware for Mars). For that you need a 5 core BFR   ;)

quint-core BFR == 45xRaptor == 310.5 mN (69.8 million lbf)  :o
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 01/01/2015 10:48 am

...

I agree with you that they don't need and it is too small for their ultimate needs (people and hardware for Mars). For that you need a 5 core BFR   ;)

quint-core BFR == 45xRaptor == 310.5 mN (69.8 million lbf)  :o

Yes, then you have a beast of a rocket that would really dwarf Saturn 5  ::)
This year they can launch FH, next year the FVH  ;) and use the expierence for the BFR....

I hear that they want to manrate the FH as soon as possibele, why i do not know.
F9 is good enough for ISS.




 


 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: The Amazing Catstronaut on 01/01/2015 10:51 am

...

I agree with you that they don't need and it is too small for their ultimate needs (people and hardware for Mars). For that you need a 5 core BFR   ;)

quint-core BFR == 45xRaptor == 310.5 mN (69.8 million lbf)  :o

Gadzooks! It's bigger than Sea Dragon.  :o
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 01/01/2015 11:07 am

I hear that they want to manrate the FH as soon as possibele, why i do not know.


Where did you hear that? Garret Reisman, head of the manned SpaceX program stated very recently that there are no plans presently to manrate Falcon Heavy.

They would need to do it though if they wanted manned moon missions. Given that the similarity to Falcon 9 it should not be too hard. Maybe they just want someone to pay for it when they want it.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: go4mars on 01/01/2015 12:38 pm

...

I agree with you that they don't need and it is too small for their ultimate needs (people and hardware for Mars). For that you need a 5 core BFR   ;)

quint-core BFR == 45xRaptor == 310.5 mN (69.8 million lbf)  :o

Gadzooks! It's bigger than Sea Dragon.  :o
For payload perhaps.  But Sea Dragon assumed one 1st stage engine of 80 million pounds of thrust.  Need to uprate the raptors to perhaps 2 million pounds thrust each.  ;)

But we're getting beyond the scope of this thread.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 01/01/2015 02:17 pm

I hear that they want to manrate the FH as soon as possibele, why i do not know.


Where did you hear that? Garret Reisman, head of the manned SpaceX program stated very recently that there are no plans presently to manrate Falcon Heavy.

They would need to do it though if they wanted manned moon missions. Given that the similarity to Falcon 9 it should not be too hard. Maybe they just want someone to pay for it when they want it.

Well i read it here,  www.tencate.com/txtures/039-Spring-2014/Protecting-people-in-space.aspx
In the Dutch version they write it even a bit better/stronger
They also write that the implementation of composites and certification on F9 and FH is an ongoing proces.
This is no surprise because of the iterative way SpaceX innovates.
To make the FH boosters as light as possible the use of composites (glare) is a must.
Glare is also used in the Airbus superjumbo. It is developed in the Technical University Delft together with Ten Cate. Now they are developing a new composite that can also be used in BFR.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 01/01/2015 03:17 pm

To make the FH boosters as light as possible the use of composites (glare) is a must.


Wrong, the FH boosters are the same as the core except for longer tanks
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: RonM on 01/01/2015 03:32 pm

To make the FH boosters as light as possible the use of composites (glare) is a must.


Wrong, the FH boosters are the same as the core except for longer tanks

Jim is right again. The FH is a three core version of the F9, not something totally new. That keeps costs down and profits up. The FH boosters have to be longer for performance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cambrianera on 01/01/2015 03:43 pm
Composite will be likely used for the nose cone of the boosters, taking part of the space now occupied by interstage (also composite construction).
Tanks will be Al-Li same construction as F9.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 01/01/2015 04:26 pm
http://www.tencate.com/txtures/039-Spring-2014/Protecting-people-in-space.aspx

That article does indeed mention manned missions with Falcon Heavy. I still go with Garrett Reisman who said more recently that there are no current plans to manrate Falcon Heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/01/2015 04:41 pm
http://www.tencate.com/txtures/039-Spring-2014/Protecting-people-in-space.aspx

That article does indeed mention manned missions with Falcon Heavy. I still go with Garrett Reisman who said more recently that there are no current plans to manrate Falcon Heavy.
He didn't say that definitively; he said he didn't know.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 01/01/2015 06:31 pm
http://www.tencate.com/txtures/039-Spring-2014/Protecting-people-in-space.aspx

That article does indeed mention manned missions with Falcon Heavy. I still go with Garrett Reisman who said more recently that there are no current plans to manrate Falcon Heavy.
He didn't say that definitively; he said he didn't know.

He was unsure about many things regarding Falcon Heavy. He was quite clear and confident on this point.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 01/01/2015 08:35 pm

To make the FH boosters as light as possible the use of composites (glare) is a must.


Wrong, the FH boosters are the same as the core except for longer tanks

Jim is right again. The FH is a three core version of the F9, not something totally new. That keeps costs down and profits up. The FH boosters have to be longer for performance.

Sorry but you both are wrong. Core and boosters are not the same.
FH booster cannot like the core segment support the second stage with payload.
The boosters are a lot longer than the center core.
The article clearly states that more and more advanced textiles are being used in F9 \ FH ( they do the same with 3d printed parts )
Yes they are produced on the same production line with the same tooling and tanks of Al - Li

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/01/2015 08:41 pm

To make the FH boosters as light as possible the use of composites (glare) is a must.


Wrong, the FH boosters are the same as the core except for longer tanks

Jim is right again. The FH is a three core version of the F9, not something totally new. That keeps costs down and profits up. The FH boosters have to be longer for performance.

Sorry but you both are wrong. Core and boosters are not the same.
FH booster cannot like the core segment support the second stage with payload.
The boosters are a lot longer than the center core.
The article clearly states that more and more advanced textiles are being used in F9 \ FH ( they do the same with 3d printed parts )
Yes they are produced on the same production line with the same tooling and tanks of Al - Li
What article?

The boosters are essentially the same other than the length. The reason they have better mass fraction is that the engine and thrust structure and plumbing mass is the same but the tanks (and thus propellant load) is greater. And sure the boosters can't withstand a 2nd stage with payload, but they do withstand roughly the same mass in extra propellant.


Least favorite thing about the Internet: people who find ways to misconstrue someone's statement (or insert their own overly-specific interpretation of a general piece of knowledge), then claim they're "wrong."
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 01/01/2015 08:43 pm

Sorry but you both are wrong.


Quite wrong.  That is not an "article", it is a supplier marketing website and not a valid source.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Comga on 01/01/2015 08:53 pm

Sorry but you both are wrong.

Quite wrong.  That is not an "article", it is a marketing website and not a valid source.

A Robotbeat said, this is the unpleasant side of the internet.  It is not a contest about who can post "You are wrong" last, even if someone, someone, is so economical with words they omit the "You are" part.  ;)

The point was whether the FH boosters would use composite tanks.  While that might improve payload fraction, it won't happen.  They will, as said, use the same Li-Al tank structure of the F9 and FH core.  There is significant evidence that they will be longer than the core.   The F9 interstage is composite, so it is a reasonable conclusion that the FH interstage will be too.  SpaceX has shown a strong preference for commonality over maximizing performance, like having one fairing that is larger than optimal for the F9 and smaller than optimal for the FH.  It is also likely that other structures, like the FH booster nose-cones may use composites. 


Anyone want to tell me that I am wrong? :P
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/01/2015 10:53 pm
Composites aren't always superior to a good high performance alloy like Al-Li, anyway. Carbon fiber isn't "black aluminum," the saying goes (taken slightly out of context).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 01/02/2015 08:44 am

Ok, next time i will write  "you might not be entirely right" or i have a different opinion.... etc...

@ Jim So websites of suppliers are not a valid source ??? Hmm SpaceX supplies launchservices to other companies...so is not a valid source as well ???

Quote
"Existing materials in a number of structures have been replaced by thermoset materials from TenCate. The value proposition of TenCate for SpaceX is our responsiveness, technical innovation, willingness to customize a solution to fit their needs, and cost leadership. We have a dedicated on-site technical engineer working hand in hand with the SpaceX team, which speeds up the learning and innovation cycle.

@ Comga, I think you are quite right...
@ Robotbeat, Glare is not Carbon Fiber but more like Aluminium Fiber...





Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cambrianera on 01/02/2015 09:42 am
Glare is glass fiber, alternated layers of aluminium and glass fiber composite.
Material cost is low and fatigue resistance much higher than aluminium.
No big advantages for short term resistance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 01/02/2015 11:26 am
Glare is glass fiber, alternated layers of aluminium and glass fiber composite.
Material cost is low and fatigue resistance much higher than aluminium.
No big advantages for short term resistance.

Yep, GLass REinforced aluminium (used for the fuselage of the A380 but also for the legs of F9)
Before they used Arimide fibers to make it stronger (Arall)
Now they are working on a new material together with the TU Delft.
They got a nice incentive from the Dutch Gouverment.
This new material could be used in BFR. I said COULD BE
The demands of SpaceX pushed their limits and they are taking pride to answer to this challenge.
In two years there will be more. Now ITAR
Anybody who took the efford to actually read their website will notice that they have also Armour materials and their involvement in F35 and other Aerospace companies.

What do you mean with no big advantages for short term resistance ?

Anything more info about manrating FH ??? There seems to be conflicting info about this.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cambrianera on 01/02/2015 11:42 am
Fatigue involves normally more cycles than envisaged in a reusable rocket.

Glass fiber has marginal advantage over metal, other than fatigue.
Glass fiber has higher mass, lower strenght and lower stiffness than carbon fiber, but it's far cheaper.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 01/02/2015 01:09 pm

Ok, next time i will write  "you might not be entirely right" or i have a different opinion.... etc...

@ Jim So websites of suppliers are not a valid source ??? Hmm SpaceX supplies launchservices to other companies...so is not a valid source as well ???


Opinion can be wrong and yours were in this case.
websites of suppliers are just PR and are not accurate.   I would not go to a Spacex website for information about a spacecraft that they are flying.

The point is that other than longer tanks, the FH boosters are the same construction as the core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 01/02/2015 01:32 pm
The point is that other than longer tanks, the FH boosters are the same construction as the core.

I don't think that the mass fraction of 1/30 that Elon Musk has mentioned is achieved only by stretching the cores. They must do something else like reducing the number of reenforcements welded in. But otherwise I agree. There is zero chance the boosters are composite.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Nomadd on 01/02/2015 03:06 pm
 Can't say I know anything specific about the FH, but it seems like the loads at that attach points being in the opposite direction for the center core and the boosters would make a difference by themselves in optimal designs. And, as ImUtrecht pointed out, why would they waste mass building the upper half of boosters strong enough to lift a 2nd stage?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/02/2015 03:14 pm
The point is that other than longer tanks, the FH boosters are the same construction as the core.

I don't think that the mass fraction of 1/30 that Elon Musk has mentioned is achieved only by stretching the cores. They must do something else like reducing the number of reenforcements welded in. But otherwise I agree. There is zero chance the boosters are composite.
Sure it can. The tanks themselves are already very lightweight, it's the engines and plumbing which have perhaps the most dry mass, and they stay the same. The core has very good mass fraction as well.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cambrianera on 01/02/2015 06:14 pm
The point is that other than longer tanks, the FH boosters are the same construction as the core.

I don't think that the mass fraction of 1/30 that Elon Musk has mentioned is achieved only by stretching the cores. They must do something else like reducing the number of reenforcements welded in. But otherwise I agree. There is zero chance the boosters are composite.

This was my take on boosters mass fraction:
http://forum.nasaspaceflight.com/index.php?topic=31514.msg1034328#msg1034328
according to my detailed evaluation of F9 v1.1 mass
http://forum.nasaspaceflight.com/index.php?topic=31514.msg1034291#msg1034291
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mme on 01/02/2015 07:41 pm
Can't say I know anything specific about the FH, but it seems like the loads at that attach points being in the opposite direction for the center core and the boosters would make a difference by themselves in optimal designs. And, as ImUtrecht pointed out, why would they waste mass building the upper half of boosters strong enough to lift a 2nd stage?
The only differences Elon Musk has ever mentioned are length and cross feed and he keeps stressing the value of commonality.  They intend to reuse the boosters so being a bit overbuilt is a good thing, not a bad thing. And the stage will still have all the interesting forces of controlled reentry on a longer "lever."  Given SpaceX's history of incremental development and improvement it just seems like they'd change the fewest variables possible and then tweak it until they are happy.

None of that is evidence they won't change how they construct the stage, but I'd be shocked.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: hrissan on 01/02/2015 09:04 pm
Can't say I know anything specific about the FH, but it seems like the loads at that attach points being in the opposite direction for the center core and the boosters would make a difference by themselves in optimal designs. And, as ImUtrecht pointed out, why would they waste mass building the upper half of boosters strong enough to lift a 2nd stage?
During the flight, the pressure inside just center core tanks is more than enough to support 2nd stage and payload (100 tonnes per 1 atmosphere difference, so if 3 atm inside, it can support 100 tonnes @ 3g!).

But the core should also support lots of weight without pressurization (vertical at pad before pressurization), it has some stiffeners inside..

Now the question is how this weight is distributed between 3 F9H cores at pad.

Either the weight is applied to just center core, or it is applied to all 3 cores via sturdy interconnects at the top of the cores.

In the first case F9H center core should support 3x weight, the side cores almost no, so central core should have more stiffeners, the side cores none.

In the second case each core supports 1/3 of F9H payload and 1/3 of second stage dry mass, and this number is also supprisingly close to F9 payload with full second stage dry mass, so all cores have the same stiffeners inside.

If you look at flight loads, applying the force of accelerating side cores at the top of the cores has the same benefits as well.

So mechanically think about this analogy: you put a platform on the 3 cores from above. The second stage rests on this platform which transfers load to 3 cores under it. During the flight this platform is pushed by all 3 cores from the bottom transferring loads to the second stage.

  2.
-----
S c S
S c S
S c S

P.S. It seems Angara A5 cores mechanically work this way...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: llanitedave on 01/02/2015 11:35 pm
Once the boosters drop off, the center core has to support everything at increased G's, so you aren't gaining anything by having the side cores support the center loads early on.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: hrissan on 01/03/2015 11:44 am
Once the boosters drop off, the center core has to support everything at increased G's, so you aren't gaining anything by having the side cores support the center loads early on.
In flight the cores support nothing, the pressure inside tanks supports everything. Vertical compression loads acting on the tank change to tension as soon as tank pressurizes (like baloon is inflated).

3 atm overpressure acting on the area of the top of the center core tank can support 100 tons at 3g.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cambrianera on 01/03/2015 12:50 pm
Once the boosters drop off, the center core has to support everything at increased G's, so you aren't gaining anything by having the side cores support the center loads early on.

You have clearly lost the first part of hrissan post (bold mine).
During the flight, the pressure inside just center core tanks is more than enough to support 2nd stage and payload (100 tonnes per 1 atmosphere difference, so if 3 atm inside, it can support 100 tonnes @ 3g!).

But the core should also support lots of weight without pressurization (vertical at pad before pressurization), it has some stiffeners inside..

Now the question is how this weight is distributed between 3 F9H cores at pad.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Herb Schaltegger on 01/03/2015 12:51 pm
Once the boosters drop off, the center core has to support everything at increased G's, so you aren't gaining anything by having the side cores support the center loads early on.
In flight the cores support nothing, the pressure inside tanks supports everything. Vertical compression loads acting on the tank change to tension as soon as tank pressurizes (like baloon is inflated).

3 atm overpressure acting on the area of the top of the center core tank can support 100 tons at 3g.

Draw a free-body diagram, then realize what forces are acting on the bottom of the core in the way of 9 Merlin engines ...
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 01/03/2015 04:31 pm
Can't say I know anything specific about the FH, but it seems like the loads at that attach points being in the opposite direction for the center core and the boosters would make a difference by themselves in optimal designs. And, as ImUtrecht pointed out, why would they waste mass building the upper half of boosters strong enough to lift a 2nd stage?

Because Spacex doesn't design for performance they design for cost.  And keeping the boosters that same as the core is one indication of this.

The forward attach points are only for side loads.  The side boosters lift from the bottom.  That is the standard practice, the shuttle was an exception.  The core and boosters are connected at the thrust sections.  Structures that are already designed for large loads. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: hrissan on 01/05/2015 01:06 pm
Can't say I know anything specific about the FH, but it seems like the loads at that attach points being in the opposite direction for the center core and the boosters would make a difference by themselves in optimal designs. And, as ImUtrecht pointed out, why would they waste mass building the upper half of boosters strong enough to lift a 2nd stage?

Because Spacex doesn't design for performance they design for cost.  And keeping the boosters that same as the core is one indication of this.

The forward attach points are only for side loads.  The side boosters lift from the bottom.  That is the standard practice, the shuttle was an exception.  The core and boosters are connected at the thrust sections.  Structures that are already designed for large loads.
Ok, clear. But then as the side cores bear less load at the pad, they just might have some internal structure not installed, making them lighter.

Otherwise, the mass factor of 1:30 is impossible to achieve. Core is 1:20, boosters are just 10% longer, not 50%.

Regarding cost optimization, boosters are already different (longer), so no big deal if some internal structure is a bit different as well, they would qualify them on the mechanical test stand anyway, so cost will stay the same if they are a bit different inside.

We should ask Elon on reddit tomorrow! :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Tomness on 01/05/2015 01:54 pm
Ok, clear. But then as the side cores bear less load at the pad, they just might have some internal structure not installed, making them lighter.

Otherwise, the mass factor of 1:30 is impossible to achieve. Core is 1:20, boosters are just 10% longer, not 50%.

Regarding cost optimization, boosters are already different (longer), so no big deal if some internal structure is a bit different as well, they would qualify them on the mechanical test stand anyway, so cost will stay the same if they are a bit different inside.

We should ask Elon on reddit tomorrow! :)
As Gwyne & Elon have said its cause they have Low-balled the numbers for F9 & you add that extra preformence coupled w/ tri-core & fabled cross-feed you get the numbers. AFAIK I am Computer-Technician not rocket enginer nor work in the Aero-space industry. Jim says what it is. Its what it is.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dglow on 01/06/2015 01:48 am
Speaking of Reddit, Elon just dropped this little gem (http://"https://www.reddit.com/r/IAmA/comments/2rgsan/i_am_elon_musk_ceocto_of_a_rocket_company_ama/cnfqcy5") WRT second stage reuse and FH:

Quote
MarsColony_in10years
In your recent MIT talk, you mentioned that you didn't think 2nd stage recovery was possible for the Falcon 9. This is due to low fuel efficiency of kerosene fuel, and the high velocities needed for many payloads (high orbits like Geostationary orbit). However, you also said that full reusability would be possible for the Mars Colonial Transporter launch vehicle.

What have you learned from flights of Falcon 9 that taught you
a) that reuse of its second stage won't be possible and
b) what you'll need to do differently with MCT to reuse its second stage.


ElonMuskOfficial
Actually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system.

MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mr. mark on 01/09/2015 06:55 pm
Interesting article about cost savings. http://spacenews.com/viasat-cites-savings-in-picking-falcon-heavy-for-2016-launch/
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MarekCyzio on 01/09/2015 06:59 pm
Is SpaceX planning Falcon SuperHeavy?

http://www.patrick.af.mil/shared/media/document/AFD-141107-004.pdf

If you look at the plans of transforming LC-13, you will notice they are building FIVE landing pads. Five not three.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: RocketmanUS on 01/09/2015 07:13 pm
Is SpaceX planning Falcon SuperHeavy?

http://www.patrick.af.mil/shared/media/document/AFD-141107-004.pdf

If you look at the plans of transforming LC-13, you will notice they are building FIVE landing pads. Five not three.
Slide 15 of that PDF
Only one land at LC-13

Slide 23
Contingency pads
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 01/09/2015 07:13 pm
No, read the document and the threads on the document.  The 5 pads aren't even for the heavy, they are for a single booster.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: RocketmanUS on 01/09/2015 07:20 pm
No, read the document and the threads on the document.  The 5 pads aren't even for the heavy, they are for a single booster.
Slide 15 also states FH.
But that would still be just one core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MarekCyzio on 01/09/2015 07:31 pm
Slide 15 of that PDF
Only one land at LC-13

Slide 23
Contingency pads

But why to build 4 contingency pads? One extra would be sufficient for 1 booster landings, for 3 booster landings you may need 4 of them. Why the fifth pad?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MTom on 01/09/2015 07:36 pm
Slide 15 of that PDF
Only one land at LC-13

Slide 23
Contingency pads

But why to build 4 contingency pads? One extra would be sufficient for 1 booster landings, for 3 booster landings you may need 4 of them. Why the fifth pad?

This has been discussed in this thread:

http://forum.nasaspaceflight.com/index.php?topic=36513.0
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Sohl on 01/09/2015 09:04 pm
Is SpaceX planning Falcon SuperHeavy?

http://www.patrick.af.mil/shared/media/document/AFD-141107-004.pdf

If you look at the plans of transforming LC-13, you will notice they are building FIVE landing pads. Five not three.

 ???

Don't know if I'd jump all the way to that conclusion.  As the others have jumped in to say, might just be for redundancy, in case there is some type of issue that ties up a landing pad or two.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 01/10/2015 08:49 am
I wouldn't rule a falcon super heavy out.

the central stage will have to use the barge (because it will be seperated far away in flight, and returning it to the launch site is pointless). the other two boosters, which fuel the central stage (with crossfeed) can return to the site. so those 2 boosters have to chose from 5 landing pads (assuming those don't just serve for launches with falcon 9 from this pad, but also launches of FH from 39A. since LC13 isn't used at all, there is no problem.

if they are really going to use a falcon superheavy with 5 cores, somebody pointed me at a nice calculation of which flight profile gives most launch capacity (he did it for a 7 core configuration aswell). and I think, it was a sequencial profile, much like an asparagus rocket in ksp that provided the highest capacity.

(in kerbal space program, asparagus rockets are rather ridiculous constructions with >16 cores, and those rockets dump the outermost stages first, in reality, those rockets would be too complex to do)

http://wiki.kerbalspaceprogram.com/wiki/Asparagus_staging
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: whvholst on 01/11/2015 04:18 pm
The text says:

"The main pad would be constructed on previously disturbed land, and it would be surrounded by an approximately 750 foot diameter compressed soil and gravel, flat pervious surface. Four additional, 150 foot diameter concrete contingency pads would also be constructed. The contingency pads would only be utilized in order to enable the safe landing of a single vehicle should last-second navigation and la nding diversion be required. There are no plans to utilize the contingency pads in order to enable landing multiple stages at LC-13 during a single landing event."

So in short: maybe, but this document does not give evidence of that.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Moe Grills on 01/11/2015 05:58 pm
Is SpaceX planning Falcon SuperHeavy?

http://www.patrick.af.mil/shared/media/document/AFD-141107-004.pdf

If you look at the plans of transforming LC-13, you will notice they are building FIVE landing pads. Five not three.

Quite logical deduction I say. It also makes sense in that Elon Musk has made no secret of his Mars ambitions
and it's clear the FH's are simply not powerful enough to support a manned Mars mission other than by a complex Earth-orbit rendezvous technique involving upto 1/2 dozen launches with its inherent difficulties or POTENTIAL failures. All it would take is one "scrub" or rendezvous failure to ruin any prospect for a TMI from LEO during a given TMI window. That expensive failure could easily bankrupt Mr. Musk.
A Falcon SuperHeavy makes sense for that ambitious prospect. 6.5 million Ibs of thrust? It could loft 100 metric tonnes into LEO. Only 2 FSH would be needed for an EOR assembly to prepare a spaceship with crew for a mission to Mars.

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/11/2015 07:30 pm
Manned missions to Mars could most certainly be done with Falcon Heavy. Half a dozen launches is nothing, we do a dozen each year to ISS. And of course you would simply plan it with enough schedule margin that a missed launch or two would be completely fine (I don't know why this idea is so hard to grasp, but it's brought up almost every time!).

The big issue is there's no reason for SpaceX to do them until they've got ISRU infrastructure set up, and by that time, Raptor and BFR/MCT will be available according to SpaceX's current plans (a month or so ago they said first BFR flight 5-6 years, although obviously that could slip--and most likely will). And a manned mission needs some way to get down to the surface and back up. The only thing that can do the latter that SpaceX has mentioned is MCT, which will use the same overall architecture as BFR.

MCT is over-sized for that, but the plus side of being over-sized is that it can be used as the transit vehicle and surface hab with plenty of room to spare (including ability to send surface equipment along with). There's definitely a possibility of launching MCT on Falcon Heavy, but given the modifications needed to the ground infrastructure to support MCT, it may easily make more sense to wait on BFR.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 01/11/2015 08:48 pm
MCT is over-sized for that, but the plus side of being over-sized is that it can be used as the transit vehicle and surface hab with plenty of room to spare (including ability to send surface equipment along with). There's definitely a possibility of launching MCT on Falcon Heavy, but given the modifications needed to the ground infrastructure to support MCT, it may easily make more sense to wait on BFR.

Yes, if they use Falcon Heavy for Mars it will be placing com sats in Orbit and/or sending rovers to the surface to verify existence of water ice. Also for placing beacons that allow MCT precision landing at the selected spot. That is really important enough and can be done with at least reuse of the side cores.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Vultur on 01/11/2015 09:05 pm
If MCT can carry 100 people for months, I'd expect it to be too heavy for Falcon Heavy to launch even empty.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/11/2015 09:26 pm
If MCT can carry 100 people for months, I'd expect it to be too heavy for Falcon Heavy to launch even empty.
Modern airliners (which are pressurized about as much as the Apollo LM was) like the stretch 737s can get down to just 200kg per seat total dry mass (and that can be improved). Also, I believe 100 passengers was the upper end of the range of MCT's capability (lower end was 50, I believe). Not more than 5-10m^3 per passenger internal volume, too. Additionally, MCT will have substantial propulsive capability and could assist the final ascent to orbit (with better Isp than Merlin). MCT's final configuration no doubt is still under substantial flux at SpaceX.

It's not obvious that falcon heavy would be incapable of launching MCT, especially with orbital insertion augmented by MCT.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/11/2015 09:37 pm
In fact, MCT on Falcon heavy would be better off with no upper stage at all. Just a funky payload adapter. Could be totally reusable. If MCT has big payload bay instead of seats, it'd be a good replacement for Shuttle's capability.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Burninate on 01/11/2015 10:32 pm
If MCT can carry 100 people for months, I'd expect it to be too heavy for Falcon Heavy to launch even empty.
Modern airliners (which are pressurized about as much as the Apollo LM was) like the stretch 737s can get down to just 200kg per seat total dry mass (and that can be improved). Also, I believe 100 passengers was the upper end of the range of MCT's capability (lower end was 50, I believe). Not more than 5-10m^3 per passenger internal volume, too. Additionally, MCT will have substantial propulsive capability and could assist the final ascent to orbit (with better Isp than Merlin). MCT's final configuration no doubt is still under substantial flux at SpaceX.

It's not obvious that falcon heavy would be incapable of launching MCT, especially with orbital insertion augmented by MCT.
A 737 doesn't have to hold a person for between 300 and 1000 days, nor deal with a closed resource loop.  I believe Musk's estimate (100 people) of ~5-10m^3 of volume ("One SUV") per passenger, and ~1 ton dry mass per passenger (100 tons), is hopeless, compatible with neither exploratory nor commercial passenger spaceflight.  Even so, ~1 ton dry mass per passenger * 100 passengers plus empty tankage (an extra ~40T) for ~600 tons fuel (6km/s is necessary to come back from the Mars surface) would make such a vehicle incompatible with Falcon Heavy.

Even vehicles adapted from Falcon Heavy have trouble.   Take a 7-core: At a 2.6% payload mass fraction (same as F9) to LEO, and a minimum ~1.15G pad acceleration (Falcon does 1.186G), 7*9 merlin 1D's at 147,000 lbf can carry up to 94.5 tons to LEO.

There just isn't enough thrust in the Merlins.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/11/2015 11:19 pm
Where does the 1 ton per passenger come from? That isn't from Musk.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 01/11/2015 11:23 pm
It's either 5-10m^3 per passenger or you don't get to go. No doubt many will choose to stay.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: tp1024 on 02/01/2015 10:12 pm
It occured to me that with the recent upgrades to the Merlin 1D engines, Falcon Heavy could have a lift-off mass of about ~1600t instead of ~1400t. With the many delays to Falcon Heavy, could it be that its construction had to be changed yet again to accomodate more fuel?

It would certainly make sense to improve the GTO payload while keeping the booster and core stages fully reusable, and perhaps avoid a barge landing of the core. I think the most likely change would be to have a larger upper stage.

Does anybody have an idea how much burden the core stage can bear? It certainly is slim already and making it even longer isn't going to help things along at all. Or could it be possible to change the diameter of the tanks by a few centimeters without having to completely retool the tank production and thus allow for more stability?

Edit: It occured to me, that the diameter was fixed because of railroad transport. Well, thicker sidewalls then? So, that would be trading additional empty mass disproportionally with additional fuel.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dante2308 on 02/01/2015 10:29 pm
There is a Falcon Heavy thread. Also M1D improvements, like crossfeed, are improvements that were long planned but have never flown. Chances are it will take quite some time for the FH to reach its advertised potential.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Damon Hill on 02/01/2015 10:39 pm
Falcon 9 cores are presently transported by highway.  Bridge/tunnel/whatever clearances certainly seem to play a part in dimensions, as does investment in production tooling--increasing core/booster diameter isn't an option without lots of other changes.  Length has already been considerably increased, perhaps more for reusability maneuvers than additional payload.   Beefing up the core will eat into payload and add some cost.

Progress on the methane Raptor engine family may determine whether a methane upper stage appears to support heavier/high energy payloads.  I think methane is where incremental performance improvements will come from.

BFR is presumably the goal for significantly larger/heavier payloads.  These apparently will much larger in diameter and may be built locally (Brownsville, TX?) and barged to east Florida/Vandenberg as is the case with Delta IV and was done with the Shuttle ET and Saturn V stages.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: tp1024 on 02/01/2015 11:20 pm
There is a Falcon Heavy thread. Also M1D improvements, like crossfeed, are improvements that were long planned but have never flown. Chances are it will take quite some time for the FH to reach its advertised potential.

Sorry, but this question was about increasing lift-off weight from 1400t (as advertised) to 1600t, which hasn't been discussed at all. So far all numbers about FH that I've seen were based on M1C (before F9 v1.1) and later M1D @ 85% thrust (along with F9 v1.1). So, the expectation is that with F9 v1.2 there will be another upgrade of FH along with it, especially since SpaceX has been working on improving M1D thrust for quite some time.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/01/2015 11:42 pm
So, the expectation is that with F9 v1.2 there will be another upgrade of FH along with it, especially since SpaceX has been working on improving M1D thrust for quite some time.

There is no V1.2 nor are they going to change the FH configuration
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ChrisWilson68 on 02/02/2015 12:06 am
There is a Falcon Heavy thread. Also M1D improvements, like crossfeed, are improvements that were long planned but have never flown. Chances are it will take quite some time for the FH to reach its advertised potential.

Sorry, but this question was about increasing lift-off weight from 1400t (as advertised) to 1600t, which hasn't been discussed at all. So far all numbers about FH that I've seen were based on M1C (before F9 v1.1) and later M1D @ 85% thrust (along with F9 v1.1). So, the expectation is that with F9 v1.2 there will be another upgrade of FH along with it, especially since SpaceX has been working on improving M1D thrust for quite some time.

I think Dante's point is that this new thrust upgrade for Merlin 1D is among the things that were already on the roadmap when SpaceX chose the current F9 v1.1 and Falcon Heavy designs.  Most people think they are already designed for the higher thrust and prop densification that are coming soon.  So there's no need for a v1.2.  It's like the legs -- the first v1.1 flew without legs, but no v1.2 was needed when legs were added because v1.2 was planned from the start to have legs.

It's public information that a flight in a few months will have the upgraded thrust, and there's no indication of a v1.2.  So v1.1 will fly with the new, higher thrust.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 02/02/2015 12:39 pm
There is a Falcon Heavy thread. Also M1D improvements, like crossfeed, are improvements that were long planned but have never flown. Chances are it will take quite some time for the FH to reach its advertised potential.

Sadly, that thread is closed.

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

So no chance to discuss this matter in the thread over there.

I can only guess, that changing the octaweb-structure to support the new engines aren't that big, and that stretching the tanks to accomodate 200t additional tons of fuel (spread over 3 cores) isn't a big thing too. So far SpaceX was very capable of designing modular systems which allow replacement or upgrades of parts.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/02/2015 12:46 pm

I can only guess, that changing the octaweb-structure to support the new engines aren't that big, and that stretching the tanks to accomodate 200t additional tons of fuel (spread over 3 cores) isn't a big thing too. So far SpaceX was very capable of designing modular systems which allow replacement or upgrades of parts.

Quite wrong, it is a big deal.  Both are nonstarters.
Octaweb is basically fixed.  Would need to change pads and test sites if there is any change in it.
Can't stretch stages, would need new erectors, new hangars, new cross country transport, new off line facilities.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dante2308 on 02/02/2015 02:51 pm
Sadly, that thread is closed.

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

So no chance to discuss this matter in the thread over there.

For the record, the linked thread is not closed.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/02/2015 08:25 pm
Sadly, that thread is closed.

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

So no chance to discuss this matter in the thread over there.

For the record, the linked thread is not closed.
It was reopened.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 02/03/2015 02:16 am
Can't stretch stages, would need new erectors, new hangars, new cross country transport, new off line facilities.

What about just a second stage stretch (length only)?  A relatively small one.  The engines are now capable of higher thrust.  Instead of using the consequently higher T/W to minimize gravity losses, they could stretch the second stage, thus raising the GLOW and returning the T/W to the original number.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Coastal Ron on 02/03/2015 02:31 am
Can't stretch stages, would need new erectors, new hangars, new cross country transport, new off line facilities.

What about just a second stage stretch (length only)?  A relatively small one.  The engines are now capable of higher thrust.  Instead of using the consequently higher T/W to minimize gravity losses, they could stretch the second stage, thus raising the GLOW and returning the T/W to the original number.

IIRC, Musk has stated that the current 1st stage is as long as can be made so that they can be landed without being too unstable/tippy.  But I know Musk and Shotwell have talked about a stretched trunk to accommodate more unpressurized cargo, so I would imagine a stretched 2nd stage would doable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Hotblack Desiato on 02/03/2015 10:38 am
Stretching the second stage is a good idea. 200t of extra fuel (or even more?) could do a lot over there.

And regarding the thread, now that the FH-speculation thread is reopened (why was it closed) how about merging the threads?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Chris Bergin on 02/03/2015 10:49 am
Merge. Yeah, sorry about the locked thread. Was an accident I guess, and it is easy to hit the lock tab as a mod! ;D

Anyhoo, FH Thread 2 reopened - as noted above - and the new thread merged.

We'll have a Thread 3 at some point - when this gets over 100,000 views.....have another article in the works too :)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Berkut on 02/03/2015 12:47 pm
We'll have a Thread 3 at some point - when this gets over 100,000 views.....have another article in the works too :)

A bit off topic but a quick question if you don't mind; How about the Raptor article you mentioned a while back?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/03/2015 12:53 pm

IIRC, Musk has stated that the current 1st stage is as long as can be made so that they can be landed without being too unstable/tippy.  But I know Musk and Shotwell have talked about a stretched trunk to accommodate more unpressurized cargo, so I would imagine a stretched 2nd stage would doable.

Trunk stretch is unrelated to a second stage stretch. A trunk stretch does not affect pad or hangar GSE, unlike a second stage stretch.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lobo on 02/03/2015 06:13 pm
Can't stretch stages, would need new erectors, new hangars, new cross country transport, new off line facilities.

What about just a second stage stretch (length only)?  A relatively small one.  The engines are now capable of higher thrust.  Instead of using the consequently higher T/W to minimize gravity losses, they could stretch the second stage, thus raising the GLOW and returning the T/W to the original number.

An issue with that might be the extra mass on the central core exceeding it's maximum bending load limits.  And is there a need for it?

If FH with all 3 cores RTLS really can get upwards of 7mt to GTO , what commercial comsats will need more than that?  (As some on the forums have estimated)

If recovering the central core down range, or expending it completely gets upwards of D4H capacity as it probably should if we assume a fully expendable FH can get 21mt to GTOm, then it could handle the big DoD/USAF birds.  Those are very expensive and expending a central core or the expense of having the barge well down range is easily absorbed.  So again, where is the stretched upper stage capacity really needed?

Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: The Amazing Catstronaut on 02/03/2015 08:55 pm
if we assume a fully expendable FH can get 21mt to GTOm, then it could handle the big DoD/USAF birds.  Those are very expensive and expending a central core or the expense of having the barge well down range is easily absorbed.  So again, where is the stretched upper stage capacity really needed?

I'm not saying that you weren't already making this point, but Fal Heavy seems to be designed to be able to take the big loads even in partially reusable config. And just because the cash wad they'd get for it would be easily enough to merit using an expendable, there's no reason not to re-use regardless and save some core manufacturing costs.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dante2308 on 02/03/2015 09:00 pm
Can't stretch stages, would need new erectors, new hangars, new cross country transport, new off line facilities.

What about just a second stage stretch (length only)?  A relatively small one.  The engines are now capable of higher thrust.  Instead of using the consequently higher T/W to minimize gravity losses, they could stretch the second stage, thus raising the GLOW and returning the T/W to the original number.

An issue with that might be the extra mass on the central core exceeding it's maximum bending load limits.  And is there a need for it?

If FH with all 3 cores RTLS really can get upwards of 7mt to GTO , what commercial comsats will need more than that?  (As some on the forums have estimated)

If recovering the central core down range, or expending it completely gets upwards of D4H capacity as it probably should if we assume a fully expendable FH can get 21mt to GTOm, then it could handle the big DoD/USAF birds.  Those are very expensive and expending a central core or the expense of having the barge well down range is easily absorbed.  So again, where is the stretched upper stage capacity really needed?

Contrary to every other launch provider apparently, Elon's goal is to reduce the cost of launches. They are trying to do this with reusable launch vehicles so your suggestion that they forgo reusing the center stage because they can simply charge a lot runs counter to the objectives of the company.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/03/2015 09:51 pm
Can't stretch stages, would need new erectors, new hangars, new cross country transport, new off line facilities.

What about just a second stage stretch (length only)?  A relatively small one.  The engines are now capable of higher thrust.  Instead of using the consequently higher T/W to minimize gravity losses, they could stretch the second stage, thus raising the GLOW and returning the T/W to the original number.

An issue with that might be the extra mass on the central core exceeding it's maximum bending load limits.  And is there a need for it?

If FH with all 3 cores RTLS really can get upwards of 7mt to GTO , what commercial comsats will need more than that?

Another 300 m/s closer to GTO?

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 02/04/2015 12:20 am
In thinking a bit more about the idea of a 2nd stage stretch, I'm now of the opinion that it isn't as good an idea as I originally thought.  When I was first considering it, it was actually in the context of the F9 (this convo. was merged into the FH thread).  And while the additional capacity it could give them on that platform might be nice, after more consideration I've come to the conclusion that SpaceX is more likely to use the increased performance to bolster their recovery attempts.  i.e. Instead of increasing payload capacity, my interpretation of SpaceX's "cost-lowering philosophy" suggests they would rather use that capacity to raise the limit for which missions they can recover a 1st stage.

This saves them the need/cost to retrofit all the ground structures and facilities that Jim points out would be necessitated by a 2nd stage stretch.  It also shrinks the gap between payloads that can be launched to GTO with F9 recovery and payloads that need a FH (RTLS ok) to reach the right orbit.  And as Lobo pointed out there just aren't that many payloads for which increased capacity on the Falcon Heavy is needed (of course that depends a bit on how the numbers for FH actually turn out IRL as opposed to on paper). 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: BobHk on 02/04/2015 05:06 am
And when your sat fleet operators insist on electric drive sats to drop their weight enough to be carried on a F9:

http://spacenews.com/41048heavyweight-ses-leans-on-europe-to-meet-spacex-launch-prices/ (http://spacenews.com/41048heavyweight-ses-leans-on-europe-to-meet-spacex-launch-prices/)

Perhaps FH doesn't need to be made to carry more weight.  SES is insisting on a lighter SAT via electric drive to be able to take advantage of SpaceX's rockets.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Galactic Penguin SST on 02/04/2015 04:28 pm
FYI, some posts about European reactions to SpaceX has been moved to this dedicated thread: http://forum.nasaspaceflight.com/index.php?topic=36707.0 (http://forum.nasaspaceflight.com/index.php?topic=36707.0)  ;)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/04/2015 04:50 pm
In thinking a bit more about the idea of a 2nd stage stretch, I'm now of the opinion that it isn't as good an idea as I originally thought.  When I was first considering it, it was actually in the context of the F9 (this convo. was merged into the FH thread).  And while the additional capacity it could give them on that platform might be nice, after more consideration I've come to the conclusion that SpaceX is more likely to use the increased performance to bolster their recovery attempts.  i.e. Instead of increasing payload capacity, my interpretation of SpaceX's "cost-lowering philosophy" suggests they would rather use that capacity to raise the limit for which missions they can recover a 1st stage.

ISTM that a 2nd stage stretch (plus maybe a bigger payload) makes it easier to recover the core. A disproportionate increase in mass of the u/s will decrease the dV from the first stage, which will make it easier to recover.



This saves them the need/cost to retrofit all the ground structures and facilities that Jim points out would be necessitated by a 2nd stage stretch.  It also shrinks the gap between payloads that can be launched to GTO with F9 recovery and payloads that need a FH (RTLS ok) to reach the right orbit.

ISTM always better to fly on F9 if that is possible, regardless whether it steals FH payloads.

What infrastructure would need to be upgraded for a u/s stretch?

The TEL would need to have a stretch between u/s Merlin / RP1 umbilicals and u/s lox umbilicals, and between there and the gripper / payload umbilicals. This would be a hassle, but perhaps not a major show-stopper if subsequent flights were all expected to be sub-cooled. I could even imagine those two sections of the TEL being adjustable (give the crew half a day to bolt in extension pieces).

If it made the rocket too long for the hangar, that would seem to be a much more serious issue.

As for whether it's likely to happen... Jim has said that a u/s stretch is the best way to increase Falcon's performance (since M1Dvac has huge thrust), but SpaceX are aiming for cost, not performance. OTOH, it would increase the number of F9 payloads that can RTLS, and that can fly on F9 instead of FH, both of which are cost winners.

cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ZachS09 on 02/04/2015 05:47 pm
If the Falcon Heavy uses cross-fed propellant, how long will the port and starboard boosters burn for? What I looked at was that the booster burn-time was unknown.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: oldAtlas_Eguy on 02/04/2015 05:50 pm
super cooling prop increases prop 2%. Using the M1D+ engines with a possible 2-5 point ISP increase possibly increases the Leo and gto payloads by ~15%.  ~60mt Leo expendable and ~24mt gto expendable. ~42mt reusable Leo and ~15mt reusable gto.

So the goal is to almost get the expendable capability for the reusable version with easy changes: engine upgrade and prop super cooling.

Edit: It is prop 2% not payload in first sentence. Corrected
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Lobo on 02/04/2015 06:11 pm
Contrary to every other launch provider apparently, Elon's goal is to reduce the cost of launches. They are trying to do this with reusable launch vehicles so your suggestion that they forgo reusing the center stage because they can simply charge a lot runs counter to the objectives of the company.

Agreed.  But the sorts of payloads that would require an FH that would need to have the core expended rather than recovered down range, are likely to be pretty few and far between.  Large USAF/DoD birds (if SpaceX can wrest some of those away from ULA) likely, that are very expensive and even a fully expendable FH would be a minor part of the overall cost...if Elon's projected costs are to be believed.   A minor part of the overall cost even for a fully expendable FH.

Almost all payloads less than that should be able to allow the central core to be recovered at the launch site or not a downrange barge.  So is it worth an upper stage core stretch?
Maybe down the road if needed, but I don't know about in the near term.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 02/04/2015 11:26 pm
super cooling prop increases prop 2%. Using the M1D+ engines with a possible 2-5 point ISP increase possibly increases the Leo and gto payloads by ~15%.  ~60mt Leo expendable and ~24mt gto expendable. ~42mt reusable Leo and ~15mt reusable gto.

So the goal is to almost get the expendable capability for the reusable version with easy changes: engine upgrade and prop super cooling.

Edit: It is prop 2% not payload in first sentence. Corrected
Honestly, I find it fairly likely that they assumed some performance increase on M1D when they were designing FH and came up with the 53t figure.

BTW, a big enough thrust increase (and perhaps a little reinforcement) would obviate the need for cross-feed. If, for example, they could get Merlin 1D to 150% it's thrust level and just started the core right before jettisoning the boosters, it'd be the same performance (or better, due to better Isp and lower gravity losses after booster sep) as cross-feed, although the load paths would be a little different.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/04/2015 11:36 pm


super cooling prop increases prop 2%.

NASA got 8%+ when sub-cooling lox, IIRC.

Is that 2% just for RP-1?

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/05/2015 08:36 am
Yup, here we are - actually 8.9%:-
http://www.grc.nasa.gov/WWW/RT/RT2001/5000/5870tomsik.html

Edit: sorry, dead link. Try:-
http://ntrs.nasa.gov/search.jsp?R=20050203875

"Test operational and performance goals with the 30 lbm/sec LO2 densifier were successfully demonstrated during the course of the program. With the STA tank volume at around 20,000 gal, the initial loaded mass of normal boiling point LO2 inside of the STA at the onset of the densification process was approximately 180,200 lb. Following completion of the 20 to 30 lbm/sec densification flow testing, experimental results indicated that by the end of the process and based on an average bulk measured temperature of 123 R, the final loaded mass of LO2 was approximately 196,300 lb. This additional loaded mass of 16,100 lb represented on average an 8.9-percent increase in onboard LO2 propellant. Test results also confirmed the presence of thermally stratified oxygen layers inside the tank. These layers varied in the vertical direction from 122 R for the colder, denser fluid at the bottom to 166 R for the warmer, less dense LO2 near the top outlet of the STA tank."

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: dorkmo on 02/05/2015 08:57 am
if the lox and rp1 densify at different percentages, would the divider within the first and second stages have to be shifted to make the lox smaller? or would you just try to densify both 2% and forgo the ~6% more the lox could go? just to keep it simple?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 02/05/2015 09:12 am
When i saw the new FH demo movie on the SpaceX site i had the impression that the Upper Stage looked longer than on the illustration on the right side of the page.
So i measured them to compare.
The diameter of the Upper Stage in the illustration is 5 mm, the length is 8 mm and the fairing has a lenght of 16 mm. In the big illustration below the fairing is also almost twice as tall as the Upper Stage. (measured from the top of the boosters).
When i look at the FH demo at time 0:33, the diameter of the us is 4 mm with a lenght of 10 mm, the payload fairing is around 12 mm long. When you look at 1:12 the fairing looks almost as tall as the Upper Stage.

So looking at the FH demo it appears that they stretched the Upper Stage a bit.
As far a i know SpaceX is still working on LC39 so they can implement all infrastructure changes they need for a longer us.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Semmel on 02/05/2015 10:49 am
In the Demo, the booster cores were as long as the central core. When I saw that for the first time, I thought that must be wrong because we know since quite a while that the side booster cores are longer than the central core. Now, is there a possibility that the video is correct on that?

Think of what happens when there is no cross-feed. If cross-feed is not used, and all engines run at the same power, the central core would run out of fuel before the side cores. This is clearly undesirable.

So there is the option to use less engines on the central core, but then there is the danger that something goes wrong as soon as all of them are lit after side engines separate. The other option is, to run the central core engines throttled down like the Delta IV Heavy. But with the extended side cores, the central core MECO would still be quite close the side cores separation.

The last solution to the problem, have shorter side boosters. So without cross-feed, is it possible that the video is correct and the side boosters are not longer than the core until cross-feed is used for the Falcon Heavy? I cant really conclude one way or the other, so can someone more knowledgeable please share some thoughts on this?

Cheers,
Semmel
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: symbios on 02/05/2015 12:44 pm
Is it really the tanks and not only that they have made room for the grid-fins in a kind of inter-stage like structure before the nose cone?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Mongo62 on 02/05/2015 02:12 pm
"These layers varied in the vertical direction from 122 R for the colder, denser fluid at the bottom to 166 R for the warmer, less dense LO2 near the top outlet of the STA tank."

They are using degrees Rankine? I've never seen it actually used outside textbook mentions.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: bstrong on 02/05/2015 02:25 pm
I grabbed a few frames from the new video and compared width/length ratios to the render on the SpaceX website. It's hard to do this with any real precision, but I keep coming to the conclusion that the ratio of the boosters is unchanged in the animation, but the core + interstage is stretched. Has anyone else attempted this comparison?

It seems incredibly unlikely that the core length is changing, but slightly more plausible that they are stretching the interstage? Could the length of the vacuum nozzle change with densification?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ImUtrecht on 02/05/2015 02:48 pm
@ Semmel

I measured the boosters 44 mm long in FH demo film, fairing 12 mm. So booster roughly 3.66 longer than fairing.
In the illustration the booster is 54 mm long, fairing 16 mm. So booster around 3.37 longer than fairing.

I agree with you that the boosters look as long as the central core in the FH video.
So i do not understand why in the FH demo the boosters appear even longer than in the illustration.
But this is marginal.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 02/05/2015 03:59 pm
In the Demo, the booster cores were as long as the central core. When I saw that for the first time, I thought that must be wrong because we know since quite a while that the side booster cores are longer than the central core. Now, is there a possibility that the video is correct on that?

Think of what happens when there is no cross-feed. If cross-feed is not used, and all engines run at the same power, the central core would run out of fuel before the side cores. This is clearly undesirable.

So there is the option to use less engines on the central core, but then there is the danger that something goes wrong as soon as all of them are lit after side engines separate. The other option is, to run the central core engines throttled down like the Delta IV Heavy. But with the extended side cores, the central core MECO would still be quite close the side cores separation.

The last solution to the problem, have shorter side boosters. So without cross-feed, is it possible that the video is correct and the side boosters are not longer than the core until cross-feed is used for the Falcon Heavy? I cant really conclude one way or the other, so can someone more knowledgeable please share some thoughts on this?

I don't believe that this will be one of the details on which the video is correct.  However, if the boosters were the same length as the core, there's a way to use them so that you can still stage them first.  Run the boosters at full thrust and keep the core throttled down as much as possible.  Alternatively, or additionally, they could fly without having all the center core's engines ignited (like they used to shut some engines down on the old F9v1.0), though I think it's very long odds that they would do that.  If they were dealing with this issue, I would expect the center to just be throttled down as far as possible.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: neoforce on 02/05/2015 04:09 pm
In the Demo, the booster cores were as long as the central core. When I saw that for the first time, I thought that must be wrong because we know since quite a while that the side booster cores are longer than the central core. Now, is there a possibility that the video is correct on that?

Think of what happens when there is no cross-feed. If cross-feed is not used, and all engines run at the same power, the central core would run out of fuel before the side cores. This is clearly undesirable.

So there is the option to use less engines on the central core, but then there is the danger that something goes wrong as soon as all of them are lit after side engines separate. The other option is, to run the central core engines throttled down like the Delta IV Heavy. But with the extended side cores, the central core MECO would still be quite close the side cores separation.

The last solution to the problem, have shorter side boosters. So without cross-feed, is it possible that the video is correct and the side boosters are not longer than the core until cross-feed is used for the Falcon Heavy? I cant really conclude one way or the other, so can someone more knowledgeable please share some thoughts on this?

I don't believe that this will be one of the details on which the video is correct.  However, if the boosters were the same length as the core, there's a way to use them so that you can still stage them first.  Run the boosters at full thrust and keep the core throttled down as much as possible.  Alternatively, or additionally, they could fly without having all the center core's engines ignited (like they used to shut some engines down on the old F9v1.0), though I think it's very long odds that they would do that.  If they were dealing with this issue, I would expect the center to just be throttled down as far as possible.

Indeed, it even says that on the spacex website at http://www.spacex.com/falcon-heavy as follows:

Quote
At liftoff, the boosters and the center core all operate at full thrust. Shortly after liftoff, the center core engines are throttled down. After the side cores separate, the center core engines throttle back up.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/05/2015 08:36 pm
"These layers varied in the vertical direction from 122 R for the colder, denser fluid at the bottom to 166 R for the warmer, less dense LO2 near the top outlet of the STA tank."

They are using degrees Rankine? I've never seen it actually used outside textbook mentions.

Follow the link to the original document, and there's a comment:-

"densifier performance testing was completed in December 2000."

The NTRS entry has a date in 2002.

I guess the industry did things differently a decade+ ago.

Cheers, Martin

Edit: whoops on the time gap.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: acsawdey on 02/05/2015 09:05 pm
Looks like NASA didn't decide to go fully metric until 2007:

http://www.space.com/3332-nasa-finally-metric.html (http://www.space.com/3332-nasa-finally-metric.html)
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Herb Schaltegger on 02/07/2015 01:27 am
"These layers varied in the vertical direction from 122 R for the colder, denser fluid at the bottom to 166 R for the warmer, less dense LO2 near the top outlet of the STA tank."

They are using degrees Rankine? I've never seen it actually used outside textbook mentions.

Most real-world thermodynamic problems require absolute temperature (e.g., Rankine or Kelvin) to solve. Even if the results are presented in some kind of relative temperature scale (C or F), the calculations themselves need to use an absolute scale.

I did plenty of homework and exam problems in Rankine as an undergrad.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 02/07/2015 02:10 am
Looks like NASA didn't decide to go fully metric until 2007:

http://www.space.com/3332-nasa-finally-metric.html (http://www.space.com/3332-nasa-finally-metric.html)
How I wish that we're true. Orion still uses imperial units.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: mvpel on 02/07/2015 03:47 am

In the Demo, the booster cores were as long as the central core. When I saw that for the first time, I thought that must be wrong because we know since quite a while that the side booster cores are longer than the central core. Now, is there a possibility that the video is correct on that?

I don't believe that this will be one of the details on which the video is correct.

I do, and always have believed that, on the other hand. I recall musing last year about what the design attributes and tradeoff a would be to make all three cores completely interchangeable. It will be interesting to see which it turns out to be.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: WmThomas on 02/07/2015 12:15 pm
Are the cores now to all be the same length? We don't know.

However, I've always doubted that having cores of different lengths would work well in SpaceX's plans for reusability. Having cores of different lengths would imply keeping separate stables of Falcon Heavy cores and Falcon 9 (and Falcon Heavy central) cores.

In terms of ground handling and fleet management, it would be better if the first-stage cores were all interchangeable. Any available core could then go into the processing flow for the next flight, be it a Falcon 9 or a Falcon Heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: rockets4life97 on 02/07/2015 12:34 pm
In terms of ground handling and fleet management, it would be better if the first-stage cores were all interchangeable.

I'd be surprised if the F9 and FH cores were all interchangeable. I think there is likely slight modifications to the center core of the FH and the side cores. So, you have 3 sets of reusable cores: F9, FH Center, FH Side.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 02/07/2015 12:36 pm
The boosters are a longer than the core, tank-wise.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: guckyfan on 02/07/2015 01:26 pm
The boosters are a longer than the core, tank-wise.

That has been the state of knowledge before that new video appeared. It is argued that it shows tanks of equal length.

I still think the side cores will be longer. I also believe that SpaceX does not regard making cores with a few differences as a difficult engineering task as long as production methods, tank diameter and bulkheads remain the same.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/07/2015 03:01 pm

I'd be surprised if the F9 and FH cores were all interchangeable. I think there is likely slight modifications to the center core of the FH and the side cores. So, you have 3 sets of reusable cores: F9, FH Center, FH Side.

Huh?  Why wouldn't the  F9 and FH cores  interchangeable?  Atlas V cores are and Spacex is more worrying about cost and standardization vs vehicle performance.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: moralec on 02/07/2015 03:57 pm


I'd be surprised if the F9 and FH cores were all interchangeable. I think there is likely slight modifications to the center core of the FH and the side cores. So, you have 3 sets of reusable cores: F9, FH Center, FH Side.

Huh?  Why wouldn't the  F9 and FH cores  interchangeable?  Atlas V cores are and Spacex is more worrying about cost and standardization vs vehicle performance.

From a production point of view, the less versions the better. That translates in lower production costs which in turn allows SpaceX to get higher margins and/or charge lower prices.

My speculation is that ALL cores will be  interchangeable, with just minor additions differentiating them. I will also expect (completely unfounded, just following this logic)  that least initially,, all 3 cores in the Falcon Heavy will end up being equal (same length, same propellant capacity) and that the core will throttle down after lift of to save propellant, until the side cores have separated.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/07/2015 07:18 pm

My speculation is that ALL cores will be  interchangeable, with just minor additions differentiating them. I will also expect (completely unfounded, just following this logic)  that least initially,, all 3 cores in the Falcon Heavy will end up being equal (same length, same propellant capacity) and that the core will throttle down after lift of to save propellant, until the side cores have separated.


There is no speculation needed, the boosters ARE longer than the core.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: sublimemarsupial on 02/07/2015 08:32 pm

My speculation is that ALL cores will be  interchangeable, with just minor additions differentiating them. I will also expect (completely unfounded, just following this logic)  that least initially,, all 3 cores in the Falcon Heavy will end up being equal (same length, same propellant capacity) and that the core will throttle down after lift of to save propellant, until the side cores have separated.


There is no speculation needed, the boosters ARE longer than the core.

Are they? Do you have info confirming that, or are you just speculating yourself?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 02/07/2015 08:34 pm
Well, the limit case is that there is left/right asymmetry on FH too.  So you'd have four classes of stage 1 cores.  Then on the other side, the proposal is that there is just one class of core, and that all cores (eventually) have propellant cross feed fittings, legs, and all the other FH "features", even if unused.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/07/2015 08:42 pm
Well, the limit case is that there is left/right asymmetry on FH too.


There doesn't have to be
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: hrissan on 02/07/2015 08:43 pm
Well, the limit case is that there is left/right asymmetry on FH too.  So you'd have four classes of stage 1 cores.  Then on the other side, the proposal is that there is just one class of core, and that all cores (eventually) have propellant cross feed fittings, legs, and all the other FH "features", even if unused.
Left/right assymerty? Are you sure? Why not rotational by 180 degrees symmetry? So the booster are not mirrored, but are exactly the same. If some connection points end up being on different sides of ground infrastructure, so be it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: moralec on 02/08/2015 12:56 am


My speculation is that ALL cores will be  interchangeable, with just minor additions differentiating them. I will also expect (completely unfounded, just following this logic)  that least initially,, all 3 cores in the Falcon Heavy will end up being equal (same length, same propellant capacity) and that the core will throttle down after lift of to save propellant, until the side cores have separated.


There is no speculation needed, the boosters ARE longer than the core.

Sorry for my ignorance Jim, I was not aware that there was certainty over this.

May I ask why was this the design choice? Wouldn't it be simpler to just use three equal cores? It probably has substantial implications over Space X's production process to have to deal with two separate core types. Is the gain in performance of having a bit of extra propellant so large that the benefits outweigh the costs? Or is there something else I'm missing?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Robotbeat on 02/08/2015 01:31 am
If the Falcon Heavy had boosters the same as the core (which IS, I believe, the same as F9's core, as well as FH's second stage being the same as F9's), then it'd have much more thrust than it'd need since it'd still have just the one upper stage. There's a lot of performance sitting there on the table, if you just stretch the boosters (and throttle down the core soon after lift-off, as you would want to do anyway). Make sense?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 02/08/2015 03:34 am
I was not claiming there was left/right asymmetry---how would I know?---just stating for the sake of discussion that there *could* be.  I don't think it would substantially affect pad flow if there was: a falcon heavy set of two or three could be treated as a unit and always fly together.

Anyway, my point was just that reasonable people could claim anywhere from one to four unique core "types".  Note that during the process of incremental development each of the initially-recovered cores is actually likely to be a unique and special snowflake, as changes are made to the design.  So all of this discussion is postulating some point in the future; it would probably be best for the proposers to be clear about the time period they are discussing when they make their arguments. I have no horse in this race.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 02/08/2015 03:44 am
Achieving reliable recovery of the boosters and core and their reuse might largely obviate any losses from giving up standardization.  If they don't have to build that many core/booster sets for the FH but can keep reusing them the penalty for having to individually modify each is spread out over all flights.  Still a big if.  Hopefully tomorrow will move SpaceX one more step closer.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 02/08/2015 06:03 am
Well, the limit case is that there is left/right asymmetry on FH too.  So you'd have four classes of stage 1 cores.  Then on the other side, the proposal is that there is just one class of core, and that all cores (eventually) have propellant cross feed fittings, legs, and all the other FH "features", even if unused.
Left/right assymerty? Are you sure? Why not rotational by 180 degrees symmetry? So the booster are not mirrored, but are exactly the same. If some connection points end up being on different sides of ground infrastructure, so be it.
Yeah, exactly: rotational symmetry dictates ground connections on the sides, or else one booster is going to get connected on the side facing away from the TE.  There's also a cable duct and some other asymmetric features (like the logo!).  Rotational symmetry will make the two sides not "appear" to match.

None of which says it's impossible, of course---but it should be obvious enough to easily tell when the first FH gets rolled out to the pad.

FWIW my flying FH model is not rotationally symmetric. The two boosters are not interchangeable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/08/2015 11:48 am

Yeah, exactly: rotational symmetry dictates ground connections on the sides, or else one booster is going to get connected on the side facing away from the TE.  There's also a cable duct and some other asymmetric features (like the logo!).  Rotational symmetry will make the two sides not "appear" to match.

None of which says it's impossible, of course---but it should be obvious enough to easily tell when the first FH gets rolled out to the pad.


That was the plan for the Atlas V heavy.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 02/08/2015 03:28 pm



That was the plan for the Atlas V heavy.

Out of curiosity, which was it: connections on the sides, or one connection on the "front"?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/08/2015 03:32 pm



That was the plan for the Atlas V heavy.

Out of curiosity, which was it: connections on the sides, or one connection on the "front"?

Front.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: AJW on 02/08/2015 03:36 pm
From the DSCOVR thread...
Something from "jardeon" on the SpaceX subreddit:
Quote
A couple of things overheard (and off the record) from the NASA KSC news room:
The barge cannot return to Jacksonville with the booster until absolute low tide, due to the height of the booster and the clearance of the bridge.

If this is an issue with F9, won't this issue be exacerbated with a stretched FH core?
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Jim on 02/08/2015 03:38 pm
From the DSCOVR thread...
Something from "jardeon" on the SpaceX subreddit:
Quote
A couple of things overheard (and off the record) from the NASA KSC news room:
The barge cannot return to Jacksonville with the booster until absolute low tide, due to the height of the booster and the clearance of the bridge.

If this is an issue with F9, won't this issue be exacerbated with a stretched FH core?

again, JAX is likely a temp staging area
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 02/08/2015 04:32 pm
From the DSCOVR thread...
Something from "jardeon" on the SpaceX subreddit:
Quote
A couple of things overheard (and off the record) from the NASA KSC news room:
The barge cannot return to Jacksonville with the booster until absolute low tide, due to the height of the booster and the clearance of the bridge.

If this is an issue with F9, won't this issue be exacerbated with a stretched FH core?

again, JAX is likely a temp staging area
In fact, we *know* that the present docking area is temporary; over on the ASDS thread someone dug up the plans to turn the current ASDS/cruise ship berths into a cargo terminal for Hohsin.  It's even known where the cruise ship will be relocated.

Of course, SpaceX could be staying in JAX. Or they could move to the cape. Or something else. But they're definitely not staying exactly where they are.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Ohsin on 02/08/2015 05:02 pm
From the DSCOVR thread...
Something from "jardeon" on the SpaceX subreddit:
Quote
A couple of things overheard (and off the record) from the NASA KSC news room:
The barge cannot return to Jacksonville with the booster until absolute low tide, due to the height of the booster and the clearance of the bridge.

If this is an issue with F9, won't this issue be exacerbated with a stretched FH core?

again, JAX is likely a temp staging area
In fact, we *know* that the present docking area is temporary; over on the ASDS thread someone dug up the plans to turn the current ASDS/cruise ship berths into a cargo terminal for Hohsin.  It's even known where the cruise ship will be relocated.

Of course, SpaceX could be staying in JAX. Or they could move to the cape. Or something else. But they're definitely not staying exactly where they are.

There is still doubts about future I just found this
http://jacksonville.com/news/metro/2013-03-21/story/hanjin-decides-against-jacksonville-cargo-terminal

They want that area to be a new cargo terminal but nothing has materialized it has been delayed for years may continue like that.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: meekGee on 02/08/2015 06:13 pm
This is of such little consequence...  The ground facilities are minimal, the amount of operations is small, it does not affect the next launch anyway...  Jacksonville works for now.  Since the first stages are not heading straight back to the cape anyway, it's just where they could get dock space and convenient access.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: MP99 on 02/08/2015 07:05 pm


Well, the limit case is that there is left/right asymmetry on FH too.  So you'd have four classes of stage 1 cores.  Then on the other side, the proposal is that there is just one class of core, and that all cores (eventually) have propellant cross feed fittings, legs, and all the other FH "features", even if unused.
Left/right assymerty? Are you sure? Why not rotational by 180 degrees symmetry? So the booster are not mirrored, but are exactly the same. If some connection points end up being on different sides of ground infrastructure, so be it.
Yeah, exactly: rotational symmetry dictates ground connections on the sides, or else one booster is going to get connected on the side facing away from the TE.  There's also a cable duct and some other asymmetric features (like the logo!).  Rotational symmetry will make the two sides not "appear" to match.

None of which says it's impossible, of course---but it should be obvious enough to easily tell when the first FH gets rolled out to the pad.

FWIW my flying FH model is not rotationally symmetric. The two boosters are not interchangeable.

The boosters would need to be rotated if they can only connect from one side.

If each booster could connect on either left or right side (perhaps by fitting a connection kit), then they could swap sides and still not need mirrored ground connections.

Cheers, Martin
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 02/09/2015 02:25 pm
Yeah, exactly: rotational symmetry dictates ground connections on the sides, or else one booster is going to get connected on the side facing away from the TE.  There's also a cable duct and some other asymmetric features (like the logo!).  Rotational symmetry will make the two sides not "appear" to match.

None of which says it's impossible, of course---but it should be obvious enough to easily tell when the first FH gets rolled out to the pad.

If you look at the video carefully, you'll notice that the right side booster (as viewed with T/E in the back) is rotated 180 deg compared to the other two cores. Atlas-like solution vs. the way Delta did it.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: cscott on 02/09/2015 10:14 pm
Yeah, exactly: rotational symmetry dictates ground connections on the sides, or else one booster is going to get connected on the side facing away from the TE.  There's also a cable duct and some other asymmetric features (like the logo!).  Rotational symmetry will make the two sides not "appear" to match.

None of which says it's impossible, of course---but it should be obvious enough to easily tell when the first FH gets rolled out to the pad.

If you look at the video carefully, you'll notice that the right side booster (as viewed with T/E in the back) is rotated 180 deg compared to the other two cores. Atlas-like solution vs. the way Delta did it.

Good catch!  Most of the shots do seem to show a subtle left/right asymmetry (which points to rotational symmetry, aka that left/right boosters are identical).  In the shot just before the boosters separate, however, there seems to be a cable duct running down the same side of both boosters, which (since there is only one cable duct) is incompatible with rotational symmetry.  Strange.

Anyway, I hope we'll see actual photographs of FH before too too long.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 02/09/2015 10:54 pm
In the shot just before the boosters separate, however, there seems to be a cable duct running down the same side of both boosters, which (since there is only one cable duct) is incompatible with rotational symmetry.  Strange.

There are ducts on both sides of a core, it's just that the one with the stage relief vents is bigger and more noticeable.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 02/10/2015 03:12 am
Yeah, exactly: rotational symmetry dictates ground connections on the sides, or else one booster is going to get connected on the side facing away from the TE.  There's also a cable duct and some other asymmetric features (like the logo!).  Rotational symmetry will make the two sides not "appear" to match.

None of which says it's impossible, of course---but it should be obvious enough to easily tell when the first FH gets rolled out to the pad.

If you look at the video carefully, you'll notice that the right side booster (as viewed with T/E in the back) is rotated 180 deg compared to the other two cores. Atlas-like solution vs. the way Delta did it.

The vent is pretty clearly on opposite sides of the boosters.  I attached one example, but you can see that the corresponding vent is on the opposite side of the other booster at a later point in the video.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 02/10/2015 09:01 am
Not sure if you're arguing or agreeing with what I said. Yes, the whole rocket seems to be rotated 180 deg at certain times, but that's quite likely a snafu (a.k.a. "artistic license"), but one core is always rotated with respect to the other two.

It's also likely artistic license that the vehicle is shown flying with the booster plane aligned with the horizon, F9 guidance doesn't really care about the vehicle roll state.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ChrisWilson68 on 02/10/2015 09:19 am
It's also likely artistic license that the vehicle is shown flying with the booster plane aligned with the horizon, F9 guidance doesn't really care about the vehicle roll state.

Of course F9 guidance cares about vehicle roll state.  Watch any video of a Falcon 9 launch and see if the vehicle is rolling.  It isn't.  That doesn't happen by accident.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: ugordan on 02/10/2015 09:26 am
Sigh.  I said roll state, not roll rate. The vehicle guidance doesn't use a roll program like older LVs did, it uses a combined pitch/yaw program. Watch the 1st F9 launch and tell me if you see the vehicle rolling *back* to the pre-liftoff roll orientation or just nulling it and keeping going. Watch any of the subsequent launches and tell me if you see any roll maneuver done post liftoff.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Chris Bergin on 02/10/2015 11:37 am
So some folk who use NSF and Reddit have been asking me about this rumor:
http://www.reddit.com/r/spacex/comments/2vbre1/falcon_heavy_hits_overpass_during_transport/

So I asked around and I'm told there was an incident. Very minor, however.

I've got another Falcon Heavy update article in draft, covering early FH flow, more 39A mod updates and some additional swooning/analysis over that epic video they published, so I'll ask them if they want to provide an official quote on it when I ask them for a final status update ahead of publication.
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: deruch on 02/10/2015 11:40 pm
Not sure if you're arguing or agreeing with what I said. Yes, the whole rocket seems to be rotated 180 deg at certain times, but that's quite likely a snafu (a.k.a. "artistic license"), but one core is always rotated with respect to the other two.

If the above is replying to me, I was posting a capture of a frame to point out what you were talking about.  It is very noticeable that the boosters are rotated 180o to each other (once you look for it anyways!).  It is maintained throughout the entire clip. 
Title: Re: SpaceX Falcon Heavy Discussion (Thread 2)
Post by: Chris Bergin on 02/16/2015 12:17 pm
Let's give this 100,000 view thread a new thread while we're housekeeping. New article in draft, just waiting for some responses back before it goes on in the coming days.

Link:
http://forum.nasaspaceflight.com/index.php?topic=36806.0