Author Topic: Falcon Heavy center core - downrange barge landing or just expend it?  (Read 28545 times)

Offline meekGee

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This tweet was in the middle of 4 consecutive tweets from the same day, discussing grid fins and F9 landing, so the context is clear.

The fact that they chose to replace the chassis for JRtI is so irrelevant I'm embarrassed for you for bringing it up...  How does it affect the argument one way or the other?  He's talking about F9, about a 300x100' barge, and about flyback.  Who cares about the hull #?   

And the fact that plans change is taken for granted.  I'm not claiming to foretell the future... Just saying that the PLAN is (or at a bare minimum was less than a year ago) to fly back from the barge.


Spacenut:  Yes, I agree.  The barge is for FH center core only.  F9 flights that can't fly back will be replaced by FH with all cores returning to base.

F9 will never have rapid reusability like that (a one day turnaround), which renders your point moot. A follow-on vehicle might, but is another discussion. So it will never be economical to fly back FH/F9 cores.

A) How do you know? 
B) If the follow-on vehicle is of the same class, then it's the same barge size, and so the discussion is equally valid
C) Musk had something in mind when he said what he said about fly-back.  So irrespective if it pans out - which rocket do you think he was talking about?

A) I'm a realist. You disagree? We'll just have to revisit this a decade from now, but I'm confident in my statement.
B) Why? Why would it the same barge size? The original has already been decommissioned.
C) Not F9. To achieve rapid re=usability you'll they will have to take everything they learn from F9 and apply it to a clean sheet vehicle. Whatever follows. Something larger, in all likelihood.

Musk was clearly more general in his statement than you seem to want to admit. You apparently keep reading things in his statement that aren't there. No mention of F9. Or FH. Read it again, more carefully this time. Evidence #1. That specific barge has already been retired and replaced. Whichever platform/barge ultimately allows fly-back (if done at all) will be VERY different.

I will also suggest that if flyback is/was in the plan, then barge use is not envisioned as some temporary hack, but a permanent conop, which matches the fact that they've built one for each coast.

They couldn't possibly need two because they plan on *landing* on them? In what world do you now manage to twist the mere existence of a west coast barge into proof that it must be used to launch from?
« Last Edit: 11/07/2015 05:30 PM by meekGee »
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Offline MP99



Ok, I thought the ship/barge they landed on was self propelled.  Even at 5-6 knots.  It can travel 100 miles in a day.  How far offshore are they now?  I know the middle core on the FH would be further out, but still.  Checking and refitting 3 cores will take some time.  Ones that land back at launch site can be checked and readied while waiting on the 3rd core to get back.  I just don't see the need to launch back and take a chance at further stressing or damaging the core stage.

Let's say 5 days in, 5 days out.

Rapid reusability means one day turn-around at most, all included.

So there's a disparity there.

The only way to avoid the fly-back penalty and retain rapid reusability is fly-back.  That's all.

Maybe  they won't (fly back) and then they have to give up either performance (if they fly the core back to shore), or turn around time and launch frequency (if they haul it back by sailing). Or operate some 10 barges following your suggestion.

If you drop the rapid reuse clause, then a fleet of F9s could be operated on a longer duty cycle.

Perhaps the barge could stay on site for several days, accepting several landings and moving each F9 off the landing area. Downside: probably best to move each core to horizontal for storage, which I understand is a dangerous operation at sea.

Cheers, Martin

Offline AncientU

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I foresee the barge will, in the future, only be used for Falcon Heavy center core.  The outside cores will flyback to the launch site.  In the meantime, the two outer cores can be refitted and flown as Falcon 9's while the center core is brought back to the launch site to be mated with two more cores for another FH.  Realistically only I only see one launch every 10 days from the same launch site.  By the time they check out the rocket, replace parts, refuel, and launch.  10 days is also what ULA said about Atlas V....IF they had that big a launch rate.  That would be about 40 cores a year, which is the maximum production of both Atlas and Falcon 9 factories.  Now, reuse will allow for more launches.  How many is anyone's guess.  With three launch sites and 4 launch pads, They will be extremely busy if it ever gets to that. 

All it is going to take is one successful completely reusable BFR, and I think Falcon will go away, especially if the price of BFR is cheap.

You are assuming one single FH per launch site.  Nothing precludes having two or three... or three center cores and four boosters... or some other combination as required for high-tempo operations.  More than one ASDS is also possible. 

If the boosters come back in 15 minutes, they could launch the next day if a second center core was ready.  If the center core flies back, the ASDS only needs to reposition for next flight profile.  So many possibilities, combinations and permutations...
« Last Edit: 11/07/2015 02:04 PM by AncientU »
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Offline meekGee

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Maybe  they won't (fly back) and then they have to give up either performance (if they fly the core back to shore), or turn around time and launch frequency (if they haul it back by sailing). Or operate some 10 barges following your suggestion.

If you drop the rapid reuse clause, then a fleet of F9s could be operated on a longer duty cycle.

Perhaps the barge could stay on site for several days, accepting several landings and moving each F9 off the landing area. Downside: probably best to move each core to horizontal for storage, which I understand is a dangerous operation at sea.

Cheers, Martin

That's true.

But compare to how Musk wants MCT to come back on the same synod, even at the expense of considerable cargo. I'm still coming to terms with that, and it is a more extreme version of the same principle.

Plus, he outright said that the plan is to flyback.  The only reason it won't is if they can't make it work, but the idea of flying back is a lot less fantastic than actually hoverslamming into a barge, and people here seem to have accepted that now...
« Last Edit: 11/07/2015 02:29 PM by meekGee »
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Online Lars-J

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Plus, he outright said that the plan is to flyback.  The only reason it won't is if they can't make it work, but the idea of flying back is a lot less fantastic than actually hoverslamming into a barge, and people here seem to have accepted that now...

Huh? What? Since when? Are you claiming that landing on a barge is more radical than launching from one?

You are really going all-in on this, aren't you?

Offline meekGee

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Plus, he outright said that the plan is to flyback.  The only reason it won't is if they can't make it work, but the idea of flying back is a lot less fantastic than actually hoverslamming into a barge, and people here seem to have accepted that now...

Huh? What? Since when? Are you claiming that landing on a barge is more radical than launching from one?

You are really going all-in on this, aren't you?

Yes - soft landing on a barge, which is a tiny x-y target, while simultaneously zeroing both z and z', while the barge is rocking, and also depleting your fuel just in time, is a hell of a difficult task.  A lot more difficult than landing on a large stationary pad back at the cape.

Launching from a barge should be no different than launching GH2 from Spaceport America.  I think it's only a 2-3 engine deal, why would it be difficult?  You need a launch mount.  Either bring the launch mount to the rocket, or the rocket to the launch mount.  Both are within the realm of straight forward engineering.

As usual things go from heresy to gospel faster than you blink.  Before the barge materialized, it was impossible! crazy! and then the barge was there and suddenly it's ho hum.  But fly-back?  impossible!  crazy!    yawn.

And again, we know it's in the plan. - so quick, go tell them it's impossible, save them the embarrassment.
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Online Lars-J

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As usual things go from heresy to gospel faster than you blink.  Before the barge materialized, it was impossible! crazy! and then the barge was there and suddenly it's ho hum.  But fly-back?  impossible!  crazy!    yawn.

And again, we know it's in the plan. - so quick, go tell them it's impossible, save them the embarrassment.

Are you setting up straw men for the heck of it, or intentionally misreading posts here? Show me *one* post called it impossible. Impractical? Yes. Expensive? Yes. Therefore exceedingly unlikely to happen? Yes. Impractical != impossible.

And no one claimed that a barge landing was an impossibility. Such ideas have been considered (and discussed here) for a long time, did you miss the discussions about the Blue Origin landing patent? And that's not even the first time the idea has been floated.
« Last Edit: 11/08/2015 05:37 AM by Lars-J »

Offline TomH

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I am pretty sure that once barge landing is routine, they will refuel on the barge and fly back.

And I am absolutely certain they will not. Think of all the stuff that has to happen in order to do a pad launch; and that's with having dozens of people on hand to check everything. You're going to simply have a couple of guys load some prop and take back off? I don't think so. This isn't a helicopter; it's still a rocket! How are you going to monitor the tens of thousands of things that have to be monitored for a normal launch? You can't. And why would you waste the flight time not delivering payload? The lifetime of these things will be measured in units of hours, possibly ten hours total life flight time in the distant future if they get lucky. Why would you waste the time on the engines and fuselage, cutting the lifetime in half, while not boosting anything into space? They will not fly the thing back for the same reason they don't launch it from Hawthorne and fly it to Canaveral. They will bring it back by slow boat the same way they bring it via slow truck the first time.

And don't bring up Musk's statements. He isn't going to waste that kind of money. Saying they can fly it back is just hype about capability. He's not going to waste twenty or thirty million dollars doing what can be done for five to ten thousand.

Offline mvpel

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They will not fly the thing back for the same reason they don't launch it from Hawthorne and fly it to Canaveral. They will bring it back by slow boat the same way they bring it via slow truck the first time.

The reason they don't fly it from Hawthorne to McGregor is because it hasn't been hot-fire tested yet.

And I suspect the reason they don't fly it from McGregor to Canaveral is because doing so would require a commercial launch license for each delivery, governed by 650 pages of federal regulations.

If airlines had to do a pre-application consultation meeting, file a safety review document, a taxi-and-takeoff description, plan, and schedule, an org chart of the airline (and air traffic controllers), an airport description, a description of the training program of the ATC and pilots, a flight safety analysis, a ground safety analysis, a full description of safety-critical computing systems of the airplane including logic diagrams and software designs, flight safety design and operation data, flight termination system wiring diagrams, system test data, an environmental impact statement, an accident investigation plan, and a flight readiness and communications plan for each and every flight, you can be reasonably assured that a seat on a flight from New York to LA would cost $50,000 and they'd deliver empty airplanes from the factory to the airport, and from one airport to another, by truck.

When you're outside of the jurisdiction of the United States 300 miles offshore, and you've already landed two boosters at the Cape, I suspect that the paperwork requirements for launching from your ship and flying back there are going to be much less rigorous.

And if you look at the infrastructure - or lack thereof - for the F9R-Dev1 flights, consisting essentially of a crane and a rudimentary steel stand, the idea of refueling and launching from the ASDS doesn't seem particularly far fetched.
« Last Edit: 11/08/2015 02:03 PM by mvpel »
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Offline meekGee

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And I am absolutely certain they will not. Think of all the stuff that has to happen in order to do a pad launch; and that's with having dozens of people on hand to check everything. You're going to simply have a couple of guys load some prop and take back off? I don't think so. This isn't a helicopter; it's still a rocket! How are you going to monitor the tens of thousands of things that have to be monitored for a normal launch? You can't. And why would you waste the flight time not delivering payload? The lifetime of these things will be measured in units of hours, possibly ten hours total life flight time in the distant future if they get lucky. Why would you waste the time on the engines and fuselage, cutting the lifetime in half, while not boosting anything into space? They will not fly the thing back for the same reason they don't launch it from Hawthorne and fly it to Canaveral. They will bring it back by slow boat the same way they bring it via slow truck the first time.

And don't bring up Musk's statements. He isn't going to waste that kind of money. Saying they can fly it back is just hype about capability. He's not going to waste twenty or thirty million dollars doing what can be done for five to ten thousand.

They flew Grasshoppers with almost no infrastructure and a lot less hands.  That's the correct analogy.

If they are planning for rapid reusability, they need the stages back...  rapidly...

And said (no maybes, or mights, or possiblies) that the plan is to fly back.

It's a very partial fuel load, it's a 2-3 engine liftoff, and you don't even have to hit a launch window.

I don't get why all the push back, but at this point we'll just wait and see.

"What this guy says he'll do, he does" or something similar..  Again I don't have the original quote, I think it was the Vandenberg base commander.
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Offline Coastal Ron

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This isn't a helicopter; it's still a rocket! How are you going to monitor the tens of thousands of things that have to be monitored for a normal launch?

If all you're doing is flying the 1st stage, which is pretty much just a fuel tank with engines on it, I'm not seeing where the complexity is at.  There is no payload, and if they have a clear corridor to fly it in where they can crash at any time in case something does go wrong, then in comparison to a helicopter it's going to be pretty simple.

That said, I think initially they will bring the barge back instead of flying the stage back, but if they do get enough demand, and the systems that support reusability get proven out, then flying a stage back from a barge should not be a big deal.

Quote
Why would you waste the time on the engines and fuselage, cutting the lifetime in half, while not boosting anything into space?

It would all boil down to cost.  The engines were supposedly designed for something like 40 reuse cycles, and we don't even know if that just means major refurbishment or decommissioning at that point.  But the cost of moving the barge is not trivial, so it would depend on flight rate - how often they would be sending the barge out and bringing it back versus how much of the lifetime of the stage they are consuming.
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Offline douglas100

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...The reason they don't fly it from Hawthorne to McGregor is because it hasn't been hot-fire tested yet.

And I suspect the reason they don't fly it from McGregor to Canaveral is because doing so would require a commercial launch license for each delivery, governed by 650 pages of federal regulations...

Are you joking? Do you think that launching even a partially fueled F9 from Hawthhorne would ever be allowed under any circumstances? Just recall the size of the fireball that the stage made on the barge when its tanks were almost empty. Now imagine the same thing happening in LA with the heavier load of prop needed to fly to Texas. What do you think the attitude of the good citizens of LA would be to SpaceX if such an accident occurred? It's crazy to think SpaceX would even consider such a thing, especially since it's so much cheaper to truck it.

Quote
And if you look at the infrastructure - or lack thereof - for the F9R-Dev1 flights, consisting essentially of a crane and a rudimentary steel stand, the idea of refueling and launching from the ASDS doesn't seem particularly far fetched.

OK, that's a reasonable point, but no one is saying that it's not technically possible. A number of us (myself included) think that it will be more expensive and complicated than shipping it back and unnecessary since it is highly unlikely that the FH will ever need to be reflown that quickly.
Douglas Clark

Offline douglas100

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If they are planning for rapid reusability, they need the stages back...  rapidly...

Then RTLS is the way to go. FH is not an optimum design for re-use. Four elements need to be integrated during processing (excluding payload of course) as opposed to two for F9. I don't buy rapid re-use for FH.
Douglas Clark

Offline douglas100

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...That said, I think initially they will bring the barge back instead of flying the stage back, but if they do get enough demand, and the systems that support reusability get proven out, then flying a stage back from a barge should not be a big deal...

...It would all boil down to cost...

Agree. Demand and cost are the drivers.
Douglas Clark

Offline spacenut

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Like I said, it makes absolutely not sense.  Cost for extra lox and diesel equipment (on a moving boat), excessive wear and tear on the entire rocket.  Paperwork and range safety for flying back the extra booster.  Grasshopper was done at a fixed location, with fixed equipment.  It also did not fly as high as the boosters, nor at the angles.  They barged back in the solid boosters for the shuttle at the cape.  The cape already set up to receive rocket barges.  They already have the lox equipment, the kerosene handling equipment, all built in.  It doesn't make sense to duplicate that on a boat going alongside the barge to fuel up the rocket.  And like someone said, the legs aren't designed to handle as much weight.  Grasshopper was taken back to the launch pad to be refueled to launch.  Maybe grasshopper rocket was supported before launch and all the weight of fueling wasn't on the legs. 

Several more reasons.  They can launch one or two Falcon 9's while waiting for the FH core to be brought back.  They don't need it immediately.  With two launch pads a the cape, one at Boca Chica, and one at Vandenberg soon.  They will have plenty of launches to do while awaiting core stages to return to any of the launch sites.  Falcon 9's and the FH side boosters will land back at the launch sites so they will be busy refurbishing those. 

There is just no need for boost back to the cape, not in the foreseeable future. 

Offline MP99

When you're outside of the jurisdiction of the United States 300 miles offshore, and you've already landed two boosters at the Cape, I suspect that the paperwork requirements for launching from your ship and flying back there are going to be much less rigorous.

ISTM that's fine, until you get 299 miles offshore, then those requirements will kick in, anyway?


It would all boil down to cost.  The engines were supposedly designed for something like 40 reuse cycles, and we don't even know if that just means major refurbishment or decommissioning at that point.  But the cost of moving the barge is not trivial, so it would depend on flight rate - how often they would be sending the barge out and bringing it back versus how much of the lifetime of the stage they are consuming.

ISTM they will need to do the same clearing of the flight path for the flight back that they currently do for a launch. That is a lot of inconvenience to other marine users, and ISTM only acceptable for a launch because there is no other way to get to space.

When it becomes a matter of cost to SpaceX (cheaper to have a few cores and fly them back, than to have a whole fleet and ship them back), they will be told to take a long walk off a short pier.

Cheers, Martin

Offline spacenut

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It doesn't take a fleet to bring one barge back.

One FH launch at pad 39A, one barge for downstream, two flyback to pad.  2 day barge back tops. 

Two days later, one launch at Boca Chica, one barge back to Boca Chica in two days.

Two days after Boca Chica launch, one launch at Vandenberg, one barge back to Vandenberg in two days. 

Day 7, launch at pad 40, barge back in two days to cape.

In the meantime, one launch a day of Falcon 9's can take place at one of the 4 places with boost back to pad. 

Maximum only three barges needed.  Maybe even two.  Launches at Boca Chica could fly over the cape with center core landing at cape.  No need for Boca Chica barge. 

I feel that with all the Falcon 9 launches for the LEO internet going on, Falcon Heavy launches will not need but one barge. 


Offline mvpel

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ISTM they will need to do the same clearing of the flight path for the flight back that they currently do for a launch. That is a lot of inconvenience to other marine users, and ISTM only acceptable for a launch because there is no other way to get to space.

As I see it, this inconvenience is a result of bureaucracy, and regulatory overreach, and has very little to do with actual "safety." The Space Shuttle re-entered over highly populated areas, as most of us well know:



So there's little reason, other than an absurd abundance of caution, to impose onerous restrictions on space or suborbital -ferry launches, or RTLS hops from the drone ship. Bureaucratic regulations are not laws of nature; they can be changed. And I expect that they will be in due course, as humanity expands into orbit, to the moon and asteroids, and on to the surface of Mars, and orbital launches are taking place on a daily basis. This may not be a "foreseeable" future for some, but it's becoming obvious that it is indeed foreseeable for the leaders of SpaceX.
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Offline Stan-1967

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...That said, I think initially they will bring the barge back instead of flying the stage back, but if they do get enough demand, and the systems that support reusability get proven out, then flying a stage back from a barge should not be a big deal...

...It would all boil down to cost...

Agree. Demand and cost are the drivers.

also....
"OK, that's a reasonable point, but no one is saying that it's not technically possible. A number of us (myself included) think that it will be more expensive and complicated than shipping it back and unnecessary since it is highly unlikely that the FH will ever need to be reflown that quickly."

and...
"Then RTLS is the way to go. FH is not an optimum design for re-use. Four elements need to be integrated during processing (excluding payload of course) as opposed to two for F9. I don't buy rapid re-use for FH."

I think there are some great points forming that will hold true if SpaceX's business continues to develop, and they will dictate the economics that will drive re-usability.

1.  FH demand and flight rate is not going to be very high in comparison to F9 single stick. 
2.  FH center core re-use does not lend itself well to rapid re-use due to integration issues.  This means that for FH with a low flight rate, rapid re-use is not of high demand, or value.
3.  Rapid re-use is being conflated with a high flight rate.   They don't have to depend on each other.  SpaceX can still have rapid flight rate if they maintain a buffer in their vehicle inventory to allow for stages to be returned from the barge before being put back into use.

Furthermore, according to Gwen Shotwell, the only F9 single stick flights that require a barge landing are to GTO.  I think GTO flights are a significant fraction of their existing manifest, but the growth they are likely to experience if low cost reuse grows the launch market, will probably be in lower orbit constellations of satellites. 

Gwen Shotwell:
Falcon Heavy is two different cores, the inner core and then the two side boosters, and the new single stick Falcon 9 will basically be a Falcon Heavy side booster. So, we're building two types of cores and that's to make sure we don't have a bunch of different configurations of the vehicle around the factory."
 
With the above economic considerations,  barge operations need to be kept below the marginal costs of making another FH center core, or side booster/F9 single stick core for each flight.   The F9H center core looks to be the most "rare" of core configurations given the probability of a low flight rate.   If re-use & market growth starts panning out for SpaceX, their launch vehicle inventory is going to be pretty heavily loaded with F9 side booster/single stick cores.   

I think the above economic considerations will put pressure to make the FH center core either disposable, or only partially re-usable.  SpaceX could probably unload significant cost on the center core if it was designed for a single use.   Weight/margins could be reduced ( increasing payload performance ), you could also rotate previously used Merlin engines from boosters into the center core.   The FH center core becomes the end of the line for re-use, and this planned obsolescence keeps the factory for building cores and engines humming at sustainable rates. 

With this model, SpaceX can have great success in reducing cost by being very good at RTLS operations alone.   The cost of barge recoveries is going to have to compete against the costs of marginal core production, and it is likely that Merlin engines partially or fully amortized on previous F9 single stick or FH side core flights will make the value a FH center core even lower to trade against barge operations.   F9 single stick cores will also become very cheap if RTLS is successful.   This again puts pressure on barge operations to be very low cost.   I could be wrong, but the prevailing thought paradigm for barge recovery keeps weighing the cost against new expensive cores.   The cost's may not look so good when weighing against cores much less expensive due to previous re-use.




Offline MP99



It doesn't take a fleet to bring one barge back.

I was talking of a fleet of F9s on a long duty cycle, not a fleet of barges.

One FH launch at pad 39A, one barge for downstream, two flyback to pad.  2 day barge back tops. 

FH cores will land a long way downrange. I don't see this coming back to shore in a couple of days when launched from Florida.

Maximum only three barges needed.  Maybe even two.  Launches at Boca Chica could fly over the cape with center core landing at cape.  No need for Boca Chica barge. 

TBH, I believe this is the ultimate solution. Boca Chica FH cores land somewhere in Florida, and trucked back to BC.

Cheers, Martin

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