Author Topic: What could push SpaceX to reconsider F9 second stage reusability?  (Read 13518 times)

Online AncientU

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Elon Musk has stated that F9 second stage reusability was not expected -- but with qualifiers that GTO/high energy orbits were too challenging.

Quote
I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles...

http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24

Lar began an interesting argument (really a discussion since Moderators don't argue) with this statement:
Quote
50 F9 or 15ish FH launches a year may be reason to revisit the decision not to do the engineering for second stage reuse

http://forum.nasaspaceflight.com/index.php?topic=36594.msg1319114#msg1319114

This is an interesting topic in and of itself, so here's a new thread to discuss it.

So the two questions are:
1) What would justify reconsideration of the expendible second F9 stage 'decision'?
2) What technology would be needed to enable cost-effective reuse?
 
These are F9/FH questions and not about the MCT.

My perspective:
Quote
A reusable second stage that returns the fairing and dispenser would make lots of sense when there are so many identical launches.  The fairing could open on one side as done on STS, or hinge back fully and then re-close.  Expendible fairings, dispensers, second stages launched week after week will be prohibitively expensive -- and the fuel to de-orbit all of this hardware (with the exception of the fairing as currently used) will need to be in the mass budget anyway.

Note: This same argument could be made for a reusable tanker second stage...

http://forum.nasaspaceflight.com/index.php?topic=36594.msg1319607#msg1319607


« Last Edit: 01/21/2015 08:19 PM by AncientU »
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Online MikeAtkinson

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First requirement is that it is economically justified. Development cost < savings in launch costs. For a 3 year payback, 50 launches /year and $10M savings / launch that seems perfectly possible.

Online MikeAtkinson

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Second requirement is for it to be technically feasible. It is known to be a hard problem, while there is no obvious reason that SpaceX cannot get it to work there may be all sorts of non-obvious things that make it uneconomic.

Online MikeAtkinson

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Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.

Online MikeAtkinson

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Fourth requirement is that SpaceX are not working on something else with equivalent functionality. E.g. a SFR.

Offline RocketmanUS

First get the F9 1st stage back and reuse
Second launch and get back ( land-landed ) and reuse Dragon ( with super Draco )

Learn from them.

Then make a reusable 2nd stage.

If it could have enough performance for Dragon cargo/crew/lab and or enough performance for some LEO payloads.
( More for a single payload )
( Just needs to lower cost enough to increase profit a little. )

And that would be a prototype for a more cost effective next generation two stage RLV.

Could also be used to test return for reuse from GTO on FH for next generation two stage RLV.

Could give them some data for their possible future MCT.

I don't see it being made just for the F9/FH. Their are new methods of manufacturing that are lowering production cost that the 2nd stage can be cheap enough to just make a new one.
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Online AncientU

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First get the F9 1st stage back and reuse
Second launch and get back ( land-landed ) and reuse Dragon ( with super Draco )

Learn from them.

Then make a reusable 2nd stage.

If it could have enough performance for Dragon cargo/crew/lab and or enough performance for some LEO payloads.
( More for a single payload )
( Just needs to lower cost enough to increase profit a little. )

And that would be a prototype for a more cost effective next generation two stage RLV.

Could also be used to test return for reuse from GTO on FH for next generation two stage RLV.

Could give them some data for their possible future MCT.

I don't see it being made just for the F9/FH. Their are new methods of manufacturing that are lowering production cost that the 2nd stage can be cheap enough to just make a new one.

I agree that once you've developed second stage reusability, its application could be used elsewhere, even where it wasn't originally deemed useful like GTO.  The F9/FH constraint on OP was just to avoid another MCT thread.
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Offline cambrianera

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A recovery kit with a mass of 400 kg or less.
Oh to be young again. . .

Offline nadreck


1) What would justify reconsideration of the expendible second F9 stage 'decision'?
2) What technology would be needed to enable cost-effective reuse?
 


1) a) (give us #2) a new development that (economically) requires significantly less TPS weight for re-entry
and
b) there have to be enough launches foreseen to justify the effort

2) a) (see 1a above) ok the lowest hanging fruit just might be a redesign of the shape of the 2nd stage (along with increasing its weight) and targeting the FH as the only cost effective lower stage
b) returning additional hardware beyond 2nd stage (dispenser, faring etc) can only fit with a tail first re-entry which to me suggests compromising the engine or going for a different engine (methalox plug nozzles around main TPS)
c) 2nd stage needs solar panels and more power storage plus greatly upgraded avionics/rcs and of course landing gear

Implications of 2a - if you think 1st stage core reuse gets down to a per use cost of $10M and you believe the goal of reuse of 2nd stage is to get a per use cost of $2.5M (assumptions: first stage cores with engines cost $50M and 2nd stages with all hardware for satellite launch and deployment cost $15M) so an F9 fully expendable is $65M per launch, an F9R1 (reusable 1st stage) is $25M, an F9HR1 is $45M, and an F9HR2 (2nd stage reusable as well) is $32.5M per flight.  I say based on this that there is NO case for a reusable F9 2nd stage if the only place it can be used is on the FH.  So eliminating a significantly heavier 2nd stage, we are left with, IMNSHO, a complete breakthrough in TPS being required and still having to give up 50% of the payload to add the other necessaries to bring the 2nd stage (Without faring and other payload hardware) back.  I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

I believe, given today's TPS technology that a returnable 2nd stage needs re-enter tail first and needs to be designed from the ground up (this would protect cargo bay style faring and it's contents).
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Online AncientU

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I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.
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Online oiorionsbelt

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I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.
But his development team is busy with a reusable 2nd stage for BFR, so another team would be needed F9 FH or BFR would be delayed. He probably has the best team available, already working on a reusable 2nd stage for BFR. I'll take an earlier BFR over reusable 2nd stage for F9 FH any day.

Online MikeAtkinson

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I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.

It depends on if they are mass limited or volume limited. If mass limited, then it might carry 2/3 the satellites at 2/3 the cost. So no net saving.

IMO they will be volume limited, so if they can launch the same number of satellites then there be a big win.

Offline nadreck

I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.

How if it costs more per launch (because you use an extra 2 cores up) to recover the 2nd stage.

Even if you could get the hypothetical reusable 2nd stage to work with a minimal payload on an F9 instead an FH you would still have to increase the number of 1st stage cores. Presuming 10 launches per recoverable 1st or 2nd stage and that any launch costs $12.5M in fixed costs, refurbishing/inspecting, etc (and I think that is truly optimistic but not impossible), then if a 1st stage costs $50M to build and a 2nd stage costs $15M then it would cost $25M to launch an F9R1 (first stage only reusable) and $12.5M to launch an F9R2(both stages recovered) so if your payload is less than half what it would be on an F9R1 then you are throwing money away even if it cost you nothing to develop F9R2.   

It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline jzjzjzj

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Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.

I'd say this is it. SpaceX will move as quick as they can to achieve the ultimate goal ("enabling people to live on other planets") given the human resources they have while making just enough money to cover the expenses.

Offline Burninate

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Take one of three options for reentry: Supersonic Retropropulsion, Magnetoshell Aerocapture, or Hypersonic Inflatable Aerodynamic Decelerators.

Mix and match descent and landing options, which are much less difficult on Earth than on Mars.

If you double the weight of the 5T upper stage using this hardware, you're reducing the payload to LEO by 5T.

...

I don't see that it's very necessary though.  The upper stages only require 1/9th of the engine hardware and 1/4th of the tank hardware as the lower stage.  Mass production is already fairly competitive with reusability.  If F9E can operate as wastefully as it does right now and still make a profit, and the lower stages can be made reusable, then the upper stage reusability will only become worth considering when launch costs are a small fraction of what they are for F9E.
« Last Edit: 01/21/2015 11:06 PM by Burninate »

Offline schaban

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First requirement is that it is economically justified. Development cost < savings in launch costs. For a 3 year payback, 50 launches /year and $10M savings / launch that seems perfectly possible.

But in 8 years they should have raptor based fully reusable rocket. Or be close to it.
So it might be profitable to develop reusable 2nd stage for Falcon but in the same time it does increases risk to their strategic product.

The only way I see them interested if they come up with minimal updates to existing 2 stage.
Something as simple as developing payload adapter to combine heat shield and parachute compartment. Would be used on selected missions, similarly to legs.

Offline Zed_Noir

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I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.

If SpaceX uses the Moog EELV secondary payload adapter (ESPA) rings to mount Elonsats of less than 182 kg each. Then in theory you could stack 12 rings to lift 72 Elonsats per flight in the standard SpaceX PLF. Mass of the Elonsats and ESPA rings is about 15 tonnes.

So in theory a total of 56 flights will complete the Elonsat constellation at a tempo of about 10 flights annually, also the number of annual Elonsat replacement flights after constellation deployment.

So the number of flights annually to send up Elonsats will be too low to justified development of a reusable 2nd stage.

Presuming the eventual Elonsat will be similar in size and mass to the Orbcomm-2 sats.

Offline TrueBlueWitt

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I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.

If SpaceX uses the Moog EELV secondary payload adapter (ESPA) rings to mount Elonsats of less than 182 kg each. Then in theory you could stack 12 rings to lift 72 Elonsats per flight in the standard SpaceX PLF. Mass of the Elonsats and ESPA rings is about 15 tonnes.

So in theory a total of 56 flights will complete the Elonsat constellation at a tempo of about 10 flights annually, also the number of annual Elonsat replacement flights after constellation deployment.

So the number of flights annually to send up Elonsats will be too low to justified development of a reusable 2nd stage.

Presuming the eventual Elonsat will be similar in size and mass to the Orbcomm-2 sats.

Math of this is eluding me..  72 Sats per launch.. 720 satellite constellation = How many total flights?

Offline Zed_Noir

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I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.

This is the crux of the issue... how low can these costs be driven. 

If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements.  ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.

If SpaceX uses the Moog EELV secondary payload adapter (ESPA) rings to mount Elonsats of less than 182 kg each. Then in theory you could stack 12 rings to lift 72 Elonsats per flight in the standard SpaceX PLF. Mass of the Elonsats and ESPA rings is about 15 tonnes.

So in theory a total of 56 flights will complete the Elonsat constellation at a tempo of about 10 flights annually, also the number of annual Elonsat replacement flights after constellation deployment.

So the number of flights annually to send up Elonsats will be too low to justified development of a reusable 2nd stage.

Presuming the eventual Elonsat will be similar in size and mass to the Orbcomm-2 sats.

Math of this is eluding me..  72 Sats per launch.. 720 satellite constellation = How many total flights?

Musk was talking about 4025 Sats for his constellation. 648 is the number for the OneWeb constellation.

See this thread
« Last Edit: 01/22/2015 02:14 AM by Zed_Noir »

Online A_M_Swallow

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Can the second stage engine be used as the main engine of the capsule?
If so they can be merged into a single spacecraft.

Offline wannamoonbase

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I'm just going to throw out a simple one:
It's harder than people think.

I'd love to see a reuseable second stage on the FH but so far SpaceX has not shown any interest in varying equipment if not needed.

Also, if the first stages become reuseable there could be Merlin 1D production capacity available that would be a fix cost and sitting idle if the vacuum version was also reuseable.

Excited to be finally into the first Falcon Heavy flow, we are getting so close!

Offline Eric Hedman

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Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.

I'd say this is it. SpaceX will move as quick as they can to achieve the ultimate goal ("enabling people to live on other planets") given the human resources they have while making just enough money to cover the expenses.
If I were on the board of SpaceX and they were trying to only make just enough money to cover expenses while going after another goal, I'd vote to fire management.  The first goal is to make as much as possible doing everything they are doing.  If any activity isn't to ultimately be as profitable as possible in their line of business, the shouldn't be doing it.  That's business 101.  The ultimate goal of any business is to make money.  If they are going to enable people to live on other planets they'd better make money at it and each step of the way or they won't get too far.

Offline pathfinder_01

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The only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.

Offline deruch

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From Elon's reddit AMA:

Quote from: /u/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.

Quote from: /u/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).

Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline RocketmanUS

Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.

I'd say this is it. SpaceX will move as quick as they can to achieve the ultimate goal ("enabling people to live on other planets") given the human resources they have while making just enough money to cover the expenses.
If I were on the board of SpaceX and they were trying to only make just enough money to cover expenses while going after another goal, I'd vote to fire management.  The first goal is to make as much as possible doing everything they are doing.  If any activity isn't to ultimately be as profitable as possible in their line of business, the shouldn't be doing it.  That's business 101.  The ultimate goal of any business is to make money.  If they are going to enable people to live on other planets they'd better make money at it and each step of the way or they won't get too far.
SpaceX is not just looking to lower space access just by reusable rockets. They are also looking at was to lower the production cost. That is to the point they don't need high production rates to keep the cost down. They are using 3D printing, and have flown a part on F9 1st stage already. Load material, program, and press start. It was faster and they said they had a better product than the old manufacturing method. With this method they don't need high production rates. One machine can make many different parts, each being different while being cheaper and better than the old way and not needing to make more than one of each.

When we finally get RLV then the production rates go down. In the old World the cost then would go up. With new methods they will be able to make their products at a lower rate while being at a lower cost than the old way.

There is more to lowering the cost of space access that just reusable stages. Their looking at the whole process and looking to apply their new methods to other industries here on Earth. If we are to venture of into and beyond our solar system we will need new methods from what we have been doing.

So for now focusing on the Falcon US for reuse would actually take them away from a means to increasing their profits. ( They don't have tunnel vision , focusing on just one thing. )
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Offline jzjzjzj

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Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.

I'd say this is it. SpaceX will move as quick as they can to achieve the ultimate goal ("enabling people to live on other planets") given the human resources they have while making just enough money to cover the expenses.
If I were on the board of SpaceX and they were trying to only make just enough money to cover expenses while going after another goal, I'd vote to fire management.  The first goal is to make as much as possible doing everything they are doing.  If any activity isn't to ultimately be as profitable as possible in their line of business, the shouldn't be doing it.  That's business 101.  The ultimate goal of any business is to make money.  If they are going to enable people to live on other planets they'd better make money at it and each step of the way or they won't get too far.

As Elon has said he didn't get into space because it would have the best return on investment. Also he won't make SpaceX public for some 15 years of precisely what you wrote.
Following was the quote I was unable to find when I posted my previous post:
Quote from: /u/ElonMuskOfficial
[..] I think our engineering resources are better spent moving on to the Mars system.
Basically - their (and worlds combined) engineering resources are limited and they can't just spend it on a project because it's profitable or because it's possible. They have a goal to follow. Which also is business 101.

So for now focusing on the Falcon US for reuse would actually take them away from a means to increasing their profits. ( They don't have tunnel vision , focusing on just one thing. )

Agreed. They could do a lot of things to make more profit (e.g. produce drywall) but they have sublime goal and that's what makes them tick in the first place.

Online AncientU

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The only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.

Isn't a 4025 short-lived satellite constellation a 'major demand?'
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Online GreenShrike

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2) What technology would be needed to enable cost-effective reuse?

One tech I haven't seen mentioned on-thread yet is propellant densification.

If sub-chilling works out -- along with the Merlin 1D thrust increase -- and the F9 can get another tonne or two to LEO, that would go some way to offsetting the mass of any second stage recovery kit, while maintaining the F9's current payload lift capability.
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Offline AJW

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Is there any way to flip the question around?  Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?

Offline darkenfast

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Personally, I think they will focus on other things for now, for the reasons mentioned by others above.  But I also think that they will have to do upper stage return eventually, say for the BFR.  So, some questions: if they put a heat shield on the forward end of the stage, will they be able to keep it actively stable during re-entry without it flipping around?  Second, what do they land it with?  If they use Super Dracos on the aft end, where do they put the hypergolic fuel tanks?  Would the stage tanks support enough pressure to use pressure-fed Kestral-descended motors using residual Metholox? I'm assuming that the upper stage main engines are too powerful to use for landing.   

Offline RanulfC

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Elon Musk has stated that F9 second stage reusability was not expected -- but with qualifiers that GTO/high energy orbits were too challenging.

This is probably the KEY point in that the MAIN market and design point for the F9 has always been the GTO/GEO market and the challenge and difficulty of getting a stage back from that point is currently prohibitive. IF the market/opertations were to change to make LEO a priority this would be a significant "reason" for Elon/SpaceX to reconsider the current direction but probably not enough IMHO.

Secondly as quoted from Elon:
Quote
I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles...

As noted while Kerolox is "ok" for most uses even with propellant densification as noted above it just doesn't have enough "energy" to be efficient enough to cover the payload penalty of GTO/GEO/High-Energy recovery mass required. My personal "bias" of course would be to use densified Cryo-Propane/Lox if the Merlin-Vac could be modifed to burn such a propellant mix simply because it "fits" in the current tanks and provides a higher ISP very close to methalox given all else is equal. But the current factors are that by using the Merlin-Vac and current manufacturing and kerolox all (pretty much) common with the first stage makes the current second stage "cheap-and-easy" to build as an expendable rather than bother with attempting to reuse/recover.

(And lets face it. "Converting" the Merlin to run on Propane/LOX is probably on par with converting it to run on Methalox. IE; Might as well just go on to develop the Raptor and keep the F9 familiy the way it is. The only engine we KNOW has run on propane is the RL10 and you'd need about 5 of them to equal a single Merlin so... :) )

And none of this actually address' the mass penalty for the required recovery/reuse gear that would have to be added to the second stage and would probably STILL require a payload hit that the F9 really can't affored.

Hmmmm... Now "win/win" might be someone ELSE developing a recoverable/reusable "second" stage to be launched on the F9R first stage and basically "hiring" SpaceX to launch that...
But that's just "me" dreaming I suppose :)

Quote
These are F9/FH questions and not about the MCT.

Actually its more about F9 because for "some" cases the FH might be able actually handle the added mass, its operations costs are going to be higher no matter what which actually doesn't help the case at hand. A reusable second stage is going to end up being a SIGNIFICANT "departure" from the economics of the current stage and it is VERY unlikely that the "simple" margin allowed by the FH is going to be enough to provide incentive for SpaceX to change its path. The higher operations cost of the FH is going to provide a dis-incentive I'd think for that matter over the F9R.
.... So, your saying no speculation on the FH being able to be the basis for a micro-mini-Mars-One-ish MCT then?
(Duck and Cover! ;) )

Quote
So the two questions are:
1) What would justify reconsideration of the expendible second F9 stage 'decision'?
2) What technology would be needed to enable cost-effective reuse?

1) Major operational/market/circumstance changes that turn the focus to an easier set of needs. AKA: a change from GTO/GEO to LEO as the main "aim" of SpaceX/Market.
2) I don't see any fundamental technological challenge to second stage recovery and reuse. The mass penalty needed to do so however makes the idea "non-viable" as it moves the F9 right out of the "market" and puts the payloads onto the more expensive FH.
"Cost-Effective" is really the main point rather than justification really. What would need to "change" to make it worth SpaceX's time and effort to achieve and sustain second stage recovery and reuse.

Quote
My perspective:
Quote
A reusable second stage that returns the fairing and dispenser would make lots of sense when there are so many identical launches.  The fairing could open on one side as done on STS, or hinge back fully and then re-close.  Expendible fairings, dispensers, second stages launched week after week will be prohibitively expensive -- and the fuel to de-orbit all of this hardware (with the exception of the fairing as currently used) will need to be in the mass budget anyway.

Note: This same argument could be made for a reusable tanker second stage...

As I understood the discussion cited this would be more orientated towards LEO operations where the recovery and reuse requirements are much less than doing so from GTO/GEO? The required hardware for such a reusable/recoverable second stage capable of returning from GTO/GEO would reduce the payload significantly which would require the use of the FH for launch. Would it be "cost-effective" for SpaceX to develop and deploy a highly different (and costly) second stage along with a "regular" expendable second stage to service the GTO/GEO market? Probably not.

On the other hand Elon has mentioned orbital fuel depots and on-orbit operations in a similar context before in passing so given ENOUGH flights (market) its possible though as long as we're "in-context" it needs to be kept in mind that he WAS talking about GTO/GEO and high-energy operations NOT LEO and low energy operations :)

From Elon's reddit AMA:

Quote from: /u/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.

Quote from: /u/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).

Thanks for pointing this out :) This is significant because it moves the F9R out of the picture and points out that such a second stage would then REQUIRE the FH to launch. This is NOT a "good" thing as many people think as you're now launching, recovering, and refurbishing THREE F9Rs on every launch instead of one JUST to get a reusable second stage...

Randy
« Last Edit: 01/22/2015 05:57 PM by RanulfC »
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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Is there any way to flip the question around?  Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?

100 times the orbital debris problem you had BEFORE you launched (and then kept) all that "junk" in orbit? :)

Seriously, without an on-orbit infrastructure to "salvage" and repurpose the "resources" then it IS simply "junk" and having the stuff up there does no good. You'd still need to recover, recycle/refurbish the equipment "up-there" in order to use it and you also STILL have the problem of kerolox propellant not being all that efficent to use in the first place.

Elon mentiones orbital propellant depots, but seems focused more on "Mars-Direct" type operations than orbital assembly, space docks and building up the kind of infrastructure and opertations that would use ONE M1DVac let alone 100 :)

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?

Online Lar

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If I were on the board of SpaceX and they were trying to only make just enough money to cover expenses while going after another goal, I'd vote to fire management.  The first goal is to make as much as possible doing everything they are doing.  If any activity isn't to ultimately be as profitable as possible in their line of business, the shouldn't be doing it.  That's business 101.  The ultimate goal of any business is to make money.  If they are going to enable people to live on other planets they'd better make money at it and each step of the way or they won't get too far.

I'm glad you're not on the board, I guess.

The maximum profit for SpaceX **over the lifetime of the company** is not necessarily given by the same strategy that gives the maximum profit **this quarter** .... I think Elon is playing a long game. If SpaceX is a dominant player in a transport market that sees thousands or even hundreds of thousands of metric tonnes moving between Earth and Mars, that is going to be huge. Far more profit than we can dream of. If you also include being a dominant solar system ISP, and a dominant mars surface transport provider, and a dominant supplier of refined raw materials on mars.... the mind boggles. Musk could be the worlds first trillionaire.

As long as they make enough money to keep the wheels turning, they're fine. Maximizing profit NOW is ... not the silicon valley way. That's OldSpace thinking.

Rant over.

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Is there any way to flip the question around?  Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?

100 times the orbital debris problem you had BEFORE you launched (and then kept) all that "junk" in orbit? :)

Seriously, without an on-orbit infrastructure to "salvage" and repurpose the "resources" then it IS simply "junk" and having the stuff up there does no good. You'd still need to recover, recycle/refurbish the equipment "up-there" in order to use it and you also STILL have the problem of kerolox propellant not being all that efficent to use in the first place.

Elon mentiones orbital propellant depots, but seems focused more on "Mars-Direct" type operations than orbital assembly, space docks and building up the kind of infrastructure and opertations that would use ONE M1DVac let alone 100 :)

Randy

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)
« Last Edit: 01/22/2015 09:00 PM by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline nadreck

Is there any way to flip the question around?  Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?

100 times the orbital debris problem you had BEFORE you launched (and then kept) all that "junk" in orbit? :)

Seriously, without an on-orbit infrastructure to "salvage" and repurpose the "resources" then it IS simply "junk" and having the stuff up there does no good. You'd still need to recover, recycle/refurbish the equipment "up-there" in order to use it and you also STILL have the problem of kerolox propellant not being all that efficent to use in the first place.

Elon mentiones orbital propellant depots, but seems focused more on "Mars-Direct" type operations than orbital assembly, space docks and building up the kind of infrastructure and opertations that would use ONE M1DVac let alone 100 :)

Randy

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.

[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]
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline go4mars

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I'm glad you're not on the board, I guess.

The maximum profit for SpaceX **over the lifetime of the company** is not necessarily given by the same strategy that gives the maximum profit **this quarter** .... I think Elon is playing a long game. If SpaceX is a dominant player in a transport market that sees thousands or even hundreds of thousands millions of metric tonnes moving between Earth and Mars, that is going to be huge. Far more profit than we can dream of. If you also include being a dominant solar system ISP, and a dominant mars surface transport provider, and a dominant supplier of refined raw materials on mars.... the mind boggles. Musk could be the worlds first trillionaire.

As long as they make enough money to keep the wheels turning, they're fine. Maximizing profit NOW is ... not the silicon valley way. That's OldSpace thinking.

Rant over.
Excellent Post.  But it needs correction.  Elon said "millions of tonnes of cargo".  It frames these questions about FH upper stages or SFR's to keep quotes like that forefront in mind so I fixed your error above.  ;)

http://shitelonsays.com/transcript/spacex-seattle-2015-2015-01-15
« Last Edit: 01/22/2015 09:13 PM by go4mars »
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Offline The Amazing Catstronaut

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Rant over.
Excellent Post.  But it needs correction.  Elon said "millions of tonnes of cargo".  It frames these questions about FH upper stages or SFR's to keep quotes like that forefront in mind so I fixed your error above.  ;)


[/quote]

BFR will not be the biggest FR, nor will generation one MTC be the largest MCT. We're talking space ships here; however, we're talking a good 20 years from now, minimum.

Under this frame, F9 upper stage re-use is a distraction. F9 isn't going to stay the mainstay for long; it may even begin to slip in relevance at the end of this year/first quarter next year with the F9H(r?)'s debut. Things are going to just keep on scaling; the rocket isn't going to have a lineage as long as Soyuz purely because by the time F9 would be as old as Soyuz is in the present day, spaceflight is going to be completely unrecognisable. That's a good thing.
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Offline RocketmanUS

@ AncientU

What could push SpaceX to reconsider F9 second stage reusability?

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 )

There would need to be enough per year LEO launches to justify it's development and for the needed added ground infrastructure to support it's landing and turn around. To little amount of flights and that extra cost per year would take away from the savings of just making a new US. So figure just how much that extra infrastructure and standing army ( personnel ) would cost per year. That would help in figuring out just how many LEO flights they would need per year.

GSO/escape would most likely still us expendable US on F9/FH if they did make a reusable US for them.

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Offline pathfinder_01

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The only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.

Isn't a 4025 short-lived satellite constellation a 'major demand?'

Depends on how many launches that is. They are planned to be small satellites. If they are they could tag along on other flights of disposable 2nd stages.

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The only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.

Isn't a 4025 short-lived satellite constellation a 'major demand?'

Depends on how many launches that is. They are planned to be small satellites. If they are they could tag along on other flights of disposable 2nd stages.

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.
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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 »

Online 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.
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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

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 ).
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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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Online 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)
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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
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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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