Author Topic: What could push SpaceX to reconsider F9 second stage reusability?  (Read 17294 times)

Offline pathfinder_01

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Quote from: AncientU link=topic=366



EM said a few hundred kg apiece.  As a secondary payload on every flight, every year (at today's launch rate) would take 40 years to launch -- and leave you with a total mess of dead sats in bazaar orbits.  Nope, on a $10-20B project with a potential revenue stream in the $100Bs range, you don't hitch rides like cube sats do.

The aim is 250kg, which is pretty small and he wants to increase launch rates(and only needing to produce an 2nd stage should help there). He simply figures that this project is not enough in the short term, esp. when his plans are to get to mars. He wants to bring the methane engines online then work on 2nd stage reuse.

Other than this project there are few uses for such an 2nd stage at this time period.  My own personal thoughts are that an F9 might not have enough lift capacity to make it worthwhile and the FH might cost too much for the task. BFR probably is an better fit(or planned to be) an better fit for this mission(2nd stage reuse) but needs too much development to be ready in the short term. 
« Last Edit: 01/23/2015 12:20 AM by pathfinder_01 »

Offline QuantumG

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4025 * 250kg = 1006.25 tons (multiplying false precision, yah!)

1006.25 / 53 = ~19 Falcon Heavy launches (dividing false precision, yah!)

19 * $85M = $1.615 billion

Four Falcon Heavy launches per year for five years doesn't even demand reusability, but it certainly would help.
I hear those things are awfully loud. It glides as softly as a cloud. What's it called? Monowhale!

Offline AJW

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Something would have to stop them from developing the next generation RLV , or delayed till much later than expected. ( SpaceX started in 2002 and F9 v1.0 first launched in 2010, that is eight years, we are in 2015 so no later than 2023 is a good date to set that we should see the next generation RLV )

If SpX is on an 8-year cadence as you suggest, it would be 2018, not 2023.   Besides, it looks much more like a 4-year cadence between vehicles, so 2017 using your system.

2002 - SpaceX Founded
2006 - Falcon 1
2010 - Falcon 9
2013 - Falcon 9 V1.1  (Really a 2.0)

Offline Zed_Noir

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4025 * 250kg = 1006.25 tons (multiplying false precision, yah!)

1006.25 / 53 = ~19 Falcon Heavy launches (dividing false precision, yah!)

19 * $85M = $1.615 billion

Four Falcon Heavy launches per year for five years doesn't even demand reusability, but it certainly would help.

According to your calculations that works out to about 212 Sats per Falcon Heavy launch. So how do you pack 212 Sats in a standard SpaceX PLF? Nevermind the mass for the mounting hardware for the Sats.

Offline RocketmanUS

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Something would have to stop them from developing the next generation RLV , or delayed till much later than expected. ( SpaceX started in 2002 and F9 v1.0 first launched in 2010, that is eight years, we are in 2015 so no later than 2023 is a good date to set that we should see the next generation RLV )

If SpX is on an 8-year cadence as you suggest, it would be 2018, not 2023.   Besides, it looks much more like a 4-year cadence between vehicles, so 2017 using your system.

2002 - SpaceX Founded
2006 - Falcon 1
2010 - Falcon 9
2013 - Falcon 9 V1.1  (Really a 2.0)
I was figuring from their start to the F9 v1.0.
The next vehicle would be more advanced, so I figure with a good margin.
They also still have to refly a F9 v1.1 1st stage and land-land Dragon and refly it before they have the next generation vehicle.

So it will also take time to get the satellite production up to a point were a reusable 2nd stage could be practical. At that point they might have the next gen. launching. But if it looks like it would not then it could make economic sense for them to go ahead with a reusable 2nd stage for F9/FH.

You could be right for 2018, but that would still be the first flight ( hope it is ). They will know more by beginning 2016 what path to take.

The other option would be if there becomes a paid customer that could benefit from the F9 and or FH with a reusable US ( never know ).

Offline docmordrid

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4025 * 250kg = 1006.25 tons (multiplying false precision, yah!)

1006.25 / 53 = ~19 Falcon Heavy launches (dividing false precision, yah!)

19 * $85M = $1.615 billion

Four Falcon Heavy launches per year for five years doesn't even demand reusability, but it certainly would help.

According to your calculations that works out to about 212 Sats per Falcon Heavy launch. So how do you pack 212 Sats in a standard SpaceX PLF? Nevermind the mass for the mounting hardware for the Sats.

You don't use the 5.2x13m fairing. You usere the 5.2x18-19m fairing from Bigelow's GATE 2 study, which would allow FH to launch BA-330. 

They did announce a cooperation agreement in 2012, and the GATE 2 fairing was discussed in the Bigelow updates.
« Last Edit: 01/23/2015 04:26 AM by docmordrid »
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Offline Zed_Noir

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4025 * 250kg = 1006.25 tons (multiplying false precision, yah!)

1006.25 / 53 = ~19 Falcon Heavy launches (dividing false precision, yah!)

19 * $85M = $1.615 billion

Four Falcon Heavy launches per year for five years doesn't even demand reusability, but it certainly would help.

According to your calculations that works out to about 212 Sats per Falcon Heavy launch. So how do you pack 212 Sats in a standard SpaceX PLF? Nevermind the mass for the mounting hardware for the Sats.

You don't use the 5.2x13m fairing. You usere the 5.2x18-19m fairing from Bigelow's GATE 2 study, which would allow FH to launch BA-330. 

They did announce a cooperation agreement in 2012, and the GATE 2 fairing was discussed in the Bigelow updates.

First SpaceX have to developed & qualified the stretch PLF for flight.

Then there is still the issue of how to mount 212 Sats in that stretch PLF. Which I think don't have enough volume to pack 212 Sats. You need something bigger.


Offline docmordrid

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4025 * 250kg = 1006.25 tons (multiplying false precision, yah!)

1006.25 / 53 = ~19 Falcon Heavy launches (dividing false precision, yah!)

19 * $85M = $1.615 billion

Four Falcon Heavy launches per year for five years doesn't even demand reusability, but it certainly would help.

According to your calculations that works out to about 212 Sats per Falcon Heavy launch. So how do you pack 212 Sats in a standard SpaceX PLF? Nevermind the mass for the mounting hardware for the Sats.

You don't use the 5.2x13m fairing. You usere the 5.2x18-19m fairing from Bigelow's GATE 2 study, which would allow FH to launch BA-330. 

They did announce a cooperation agreement in 2012, and the GATE 2 fairing was discussed in the Bigelow updates.

First SpaceX have to developed & qualified the stretch PLF for flight.

Then there is still the issue of how to mount 212 Sats in that stretch PLF. Which I think don't have enough volume to pack 212 Sats. You need something bigger.
I didn't specify a number of satellites, only that a stretched fairing is in the wind.

As to its dev, ISTM at most to be a ~31% stretch of an existing part in its barrel section so it's not like they're starting from scratch.
« Last Edit: 01/23/2015 05:06 AM by docmordrid »
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Offline QuantumG

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276 m3 isn't enough for 212 satellites? Just how big do you imagine these 250 kg smallsats are?

You're right about the deployment, though I think imagining something like a P-POD is wrong. Clearly you want something involving magnets  8)
I hear those things are awfully loud. It glides as softly as a cloud. What's it called? Monowhale!

Offline RanulfC

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Clearly there's a market for tugs that can harvest all that junk from wherever it may be and collect it in one place for safe keeping. Or in one place... for feeding into the maws of an on-orbit recycler.  Not this year. Not this decade. But someday. (Kero may be more useful as an organic feedstock than as fuel)

Actually that's NOT so clear or it would have been done already with a dedicated vehicle :) "Maybe-someday" is always possible but not something that you can bank on using a "new" second stage that is not optimized for the job to do it either :)

[prediction/pontification mode]And the first place there will be on orbit salvage operation will be geosynchronous and the above geosynchronous graveyard orbit with already over 2,000 tons of scrap[/prediction/pontification mode]

Again its a nice "idea" but it lacks a motivation to "lose" payload capability to install the needed hardware and systems to accomplish the job AND to provide the resupply/servicing needed to keep the system working. You're probably right about the location to start with though :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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4025 * 250kg = 1006.25 tons (multiplying false precision, yah!)

1006.25 / 53 = ~19 Falcon Heavy launches (dividing false precision, yah!)

19 * $85M = $1.615 billion

Four Falcon Heavy launches per year for five years doesn't even demand reusability, but it certainly would help.

Using the above figures it comes out to a total of 76-F9R (52.6 satellites per launch, round to 53) launches to put it all into orbit. That would be a more significant, and I believe accurate metric that trying to stuff them into an FH. (Less costly per launch as well) Spread over five years (where did we get that number again?) that's 15.2 launches per year. And as long as we're using "false" figures that would use "maybe" two F9Rs and 16 "expendable" second stages. (Assuming the figure of "10-flights" per F9R that's been mentioned is correct. 3 F9Rs would be more conservative I suppose each flying 5 missions :) )

15 "expended" second stage a year probably SOUNDS like a good reason for reuse but its not that cut and dried. That's "assuming" here that ALL the deployment and mounting hardware weighs nothing to start with which is probably not a good "assumption" to make so we can assume EVEN with expendable second stages there will have to be more flights. So we're probably up to 20 flights per year as a STARTING figure already. Well THAT has to be reason enough right? Well first of all we still haven't added anything for recovery and reusability and even if LEO IS "easier" than GTO/GEO we still have to add on the cost of a development and manufacturing, etc to the equation. And at 20 flights per year we're for all intents and purposes running through the "service-life" of two F9Rs per year which means producing two more stages every year to "replace" losses at least. (This assumes you never lose any for "other" reasons)

And at this point your payload is down still, how much exactly we don't actually know but the flight program has probably increased to at least 25, maybe 30 so we've now added a third F9R end-of-life per year. And in all we have no idea what the "life-time" of the F9R-S2R is going to be but "assume" for a moment it is on par with the F9R (being conservative it would be less but lets let that go for the moment) and that would mean we "use-up" at least three of them per year as well. And keep in mind that the supposed "F9R-S2R" is not all that "applicable" to other uses! It has no capacity or capability for delivery to GTO/GEO of payloads due to a reduced payload capability AND probably couldn't survive a return from the same even if it could do the job AND find reduced payloads. (Unless you assume here that it IS designed to do so and reduce the payload capability even further...)

Still someone will note that 3 F9R-S2R's per year versus 15 expended S2s per year has got to be cheaper, right? Maybe but that's not at all clear because the current S2 expendable has more "capability" for LEO missions than the notional "point-design" S2R does by virtue of its "design" mission which is GTO/GEO delivery. And it CAN'T really be used for any other mission as the more flexible S2E can.

All in all there IS an argument for developing a reusable F9R-S2R stage but I don't see it actually meeting the most important criteria in that it doesn't advance SpaceX to Mars and the cost arguments don't seem be enough to meet SpaceX's nominal costing criteria.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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