Author Topic: Skepticism about reusability  (Read 25472 times)

Offline Pipcard

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Skepticism about reusability
« on: 12/12/2015 07:21 AM »
On one hand, I've seen people talk about reusability as a major "game-changer" that will revolutionize everything about space access, leaving everyone who still has expendable systems in the dust.

On the other hand, I've seen people who are skeptical, saying that reusability might end up with high refurbishment and labor costs, higher unit costs due to decreased production, low market elasticity, "not enough demand for high flight rates," and it not mattering because the launch costs are only a small part of a total mission.

Is there any truth to these doubts?
« Last Edit: 12/12/2015 07:27 AM by Pipcard »

Offline NovaSilisko

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Re: Skepticism about reusability
« Reply #1 on: 12/12/2015 07:34 AM »
The best answer so far seems to be a simple "We don't really know"

SpaceX will start finding out the answers to these questions after they recover a stage intact and can start to dissect it.

I'm hopeful. But you never know.

Offline Lee Jay

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Re: Skepticism about reusability
« Reply #2 on: 12/12/2015 01:23 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Offline RonM

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Re: Skepticism about reusability
« Reply #3 on: 12/12/2015 01:59 PM »
I think the biggest issue is cost. How many flights can you get out of a reusable rocket and how much does it cost to get it ready for the next flight? I'm confident that SpaceX will eventually figure this out, but I'm not sure they will get it right the first time. We will find out soon.

Offline edkyle99

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Re: Skepticism about reusability
« Reply #4 on: 12/12/2015 02:00 PM »
It isn't just the cost of refurbishment.  It is the loss of capability.  Falcon 9 v1.1, for example, could not do useful GTO missions if first stage recovery was attempted.  Falcon Heavy will only lift 6.5 tonnes to GTO (GEO-1800 m/s) with full recovery while weighing perhaps 1,400 tonnes at lifoff - nearly 70% as much as STS.  Compare that with Atlas 521, which can lift about as much while weighing only 429 tonnes at liftoff.  Or Ariane 64, which will lift 11 tonnes to GEO-1500 m/s while weighing 800 tonnes.  Or Proton M, which can lift nearly as much to GEO-1500 m/s for half the liftoff mass despite launching from 46 degrees latitude.

 - Ed Kyle
« Last Edit: 12/12/2015 02:05 PM by edkyle99 »

Offline RonM

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Re: Skepticism about reusability
« Reply #5 on: 12/12/2015 02:28 PM »
It isn't just the cost of refurbishment.  It is the loss of capability.  Falcon 9 v1.1, for example, could not do useful GTO missions if first stage recovery was attempted.  Falcon Heavy will only lift 6.5 tonnes to GTO (GEO-1800 m/s) with full recovery while weighing perhaps 1,400 tonnes at lifoff - nearly 70% as much as STS.  Compare that with Atlas 521, which can lift about as much while weighing only 429 tonnes at liftoff.  Or Ariane 64, which will lift 11 tonnes to GEO-1500 m/s while weighing 800 tonnes.  Or Proton M, which can lift nearly as much to GEO-1500 m/s for half the liftoff mass despite launching from 46 degrees latitude.

 - Ed Kyle

Does it matter if a reusable FH is twice as massive as a Proton M if the reusable FH flight costs less? I don't think the customer will care.

Reusablity requires trade offs. Loss of capacity for more fuel to return the stage to the launch site is a trade off. If the lower mass to orbit is still enough for the payload, it doesn't matter as long as it is cheaper.

Offline Johnnyhinbos

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Re: Skepticism about reusability
« Reply #6 on: 12/12/2015 02:51 PM »
Even if it's on par cost wise (and I doubt it would be) to tossing the booster in the ocean like everyone else does, don't forget that Musk has repeatedly stated he's aiming for a much loftier goal. So by RTLS SpaceX is gaining huge experience towards achieving that long term goal.
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline Lee Jay

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Re: Skepticism about reusability
« Reply #7 on: 12/12/2015 03:13 PM »
Does it matter if a reusable FH is twice as massive as a Proton M if the reusable FH flight costs less? I don't think the customer will care.

Reusablity requires trade offs. Loss of capacity for more fuel to return the stage to the launch site is a trade off. If the lower mass to orbit is still enough for the payload, it doesn't matter as long as it is cheaper.

Yeah, it matters.  It matters because the fact that it has to be so much bigger makes it a lot harder for it to end up cheaper.

Offline JamesH

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Re: Skepticism about reusability
« Reply #8 on: 12/12/2015 03:16 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Er, Apollo? Pretty sure that was chemical, prety sure it made it to the moon. That's expansion, albeit in a very minor way, but it proved it could be done with chemical rockets. Recent images of Pluto - chemical rockets only got New Horizons there (plus Jupiter gravity assist). There is a lot that can be done with chemical propulsion. What cannot be done with it yet, is replace it with something better.

Offline Confusador

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Re: Skepticism about reusability
« Reply #9 on: 12/12/2015 03:41 PM »
BTW.... isn't the X-37 reusable?  Perhaps it is only considered partially reusable since the launch vehicle is disposed?

X-37 is a reusable spacecraft, which is a very different thing than a reusable rocket.  Every crew vehicle in development that I am aware of is planning for reusability to at least some extent, and no one thinks it's implausible.  Some people will say it's not worth it, for the low number of vehicles they expect to be built, but it's not technically all that hard.  After all, reusability will influence the design of your heatshield and landing system, but it's not what's driving you to have them in the first place.

Reusable rockets on the other hand, are a very hard thing.  I personally don't expect SpaceX to succeed economically with reusing the F9 (though I have no doubt they will refly eventually).  But they've clearly taken some good lessons away from Shuttle, DC-X, et al, and I think they'll contribute a lot to the body of knowledge.  Maybe even enough to let the next design to succeed, but at this point, as has already been said, no one really knows how many trys it's going to take.

Offline Lee Jay

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Re: Skepticism about reusability
« Reply #10 on: 12/12/2015 03:54 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Er, Apollo? Pretty sure that was chemical, prety sure it made it to the moon. That's expansion, albeit in a very minor way, but it proved it could be done with chemical rockets. Recent images of Pluto - chemical rockets only got New Horizons there (plus Jupiter gravity assist). There is a lot that can be done with chemical propulsion. What cannot be done with it yet, is replace it with something better.

It's not expansion unless we stay, reproduce, and expand the civilization.  Flags and footprints isn't expansion of the species beyond Earth anymore than a weekend vacation to the beach is the same as moving your family to the beach and living there permanently.

Offline Semmel

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Re: Skepticism about reusability
« Reply #11 on: 12/12/2015 04:19 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Why not? Question mark.

Offline Lee Jay

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Re: Skepticism about reusability
« Reply #12 on: 12/12/2015 04:26 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Why not? Question mark.

2-3% of glow gets to LEO.  Way less beyond that.

Way too much material usage, way too expensive (factor of 10,000).

Offline RonM

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Re: Skepticism about reusability
« Reply #13 on: 12/12/2015 04:28 PM »
Does it matter if a reusable FH is twice as massive as a Proton M if the reusable FH flight costs less? I don't think the customer will care.

Reusablity requires trade offs. Loss of capacity for more fuel to return the stage to the launch site is a trade off. If the lower mass to orbit is still enough for the payload, it doesn't matter as long as it is cheaper.

Yeah, it matters.  It matters because the fact that it has to be so much bigger makes it a lot harder for it to end up cheaper.

Note the part of my quoted post I put in bold. Yes, it makes it harder, but if they succeed in making it cheaper per flight than no one will care.

Without some magical technology, a reusable rocket has to be bigger to account for the extra mass that makes it reusable. There's no way around that. Getting back to the OP, that where the skepticism come from.

Offline Semmel

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Re: Skepticism about reusability
« Reply #14 on: 12/12/2015 04:33 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Why not? Question mark.

2-3% of glow gets to LEO.  Way less beyond that.

Way too much material usage, way too expensive (factor of 10,000).

You give a relative statements without providing an alternative to compare them to. Your words do not make sense to me.

Also, what does this has to do with reusability?

Offline RonM

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Re: Skepticism about reusability
« Reply #15 on: 12/12/2015 04:35 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.

Er, Apollo? Pretty sure that was chemical, prety sure it made it to the moon. That's expansion, albeit in a very minor way, but it proved it could be done with chemical rockets. Recent images of Pluto - chemical rockets only got New Horizons there (plus Jupiter gravity assist). There is a lot that can be done with chemical propulsion. What cannot be done with it yet, is replace it with something better.

It's not expansion unless we stay, reproduce, and expand the civilization.  Flags and footprints isn't expansion of the species beyond Earth anymore than a weekend vacation to the beach is the same as moving your family to the beach and living there permanently.

You have a good point, but it's off topic. The OP is about skepticism of reusable rockets, not mankind colonizing space. Reusable rockets could be very useful in lowering costs to reach orbit, if anyone can get them to work cheap enough. BEO missions, especially human BEO flights would still be very expensive. That conversation is already going on in other threads.

Offline Pipcard

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Re: Skepticism about reusability
« Reply #16 on: 12/12/2015 04:37 PM »
Does it matter if a reusable FH is twice as massive as a Proton M if the reusable FH flight costs less? I don't think the customer will care.

Reusablity requires trade offs. Loss of capacity for more fuel to return the stage to the launch site is a trade off. If the lower mass to orbit is still enough for the payload, it doesn't matter as long as it is cheaper.

Yeah, it matters.  It matters because the fact that it has to be so much bigger makes it a lot harder for it to end up cheaper.

Note the part of my quoted post I put in bold. Yes, it makes it harder, but if they succeed in making it cheaper per flight than no one will care.

Without some magical technology, a reusable rocket has to be bigger to account for the extra mass that makes it reusable. There's no way around that. Getting back to the OP, that where the skepticism come from.

How much does it cost to stretch a rocket stage?

From what I've seen, the skepticism seems to mainly come from the notion that "an RLV needs high flight rates to be economical." Also, would reusability matter if the labor is in fact the most expensive part of a launch? Here's an argument from a reusability skeptic:

Quote from: Nibb31
Reusability: Cheap spaceflight through reusability has been the holy grail of the aerospace industry since the end of Apollo. SpaceX wasn't the first to envision reusable rockets and won't be the last. The challenge never was technological. It has always been economical. Reusability only makes sense if you have high enough flight rates. Increasing flight rates does not depend solely on bringing costs down. It depends mainly on finding a purpose for those flights.

SpaceX has a high probability of finally achieving first stage recovery and reuse. That will be a great technological accomplishment, but let's remember that the goal isn't to recover or reuse stages, it is to bring costs down. Recovery and reuse do not automatically bring costs down, nor are they the only ways of bringing costs down. Ultimately, what will bring costs down is to increase flight rates in order to generate economies of scale.

Orbital launches are expensive because they employ lots of people to manufacture, test, handle, integrate, transport, and launch the rocket, but also to build payloads and ground stations, integration, fueling, handling, mission planning, mission control... There are also infrastructure costs, administrative overhead costs, facilities, power, IT, HR, training, legal, catering, etc...  The result is hundreds, if not thousands of highly qualified people, working in the aerospace industry. The biggest cost factor is not the first stage hardware, it's the payroll of a particularly expensive workforce. Recovering the first stage is not going to automatically reduce costs by 50% (or even 20%) unless it allows to fire 50% of the workforce. It only has the potential to save some of the manufacturing costs, the rest of the costs remain constant.

SpaceX has invested in facilities that can mass-produce Falcon cores. This means that if reusability comes into full swing, those facilities will be underproducing and the cost of each stage will actually increase due to the lack of economies of scale, which might negate the whole reusability business model.

This is why the competitors of SpaceX (ULA, Airbus, etc.) are in "wait and see" mode. They have their plans to incorporate reusability into their business models if they need to, but they are mainly waiting to see how the market reacts to SpaceX and if SpaceX can actually make reusability profitable before they decide whether it makes economical sense to commit to it.
« Last Edit: 12/12/2015 04:44 PM by Pipcard »

Offline IRobot

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Re: Skepticism about reusability
« Reply #17 on: 12/12/2015 04:53 PM »
We aren't going to expand beyond Earth on chemical rockets.  Period.
Bold statement. Why not? None of the foreseen future technologies is suitable for Earth launch to LEO. Fusion, etc, is for in-space travel, not for launching.

A fusion tug, for example, could basically reduce the in space fuel requirements 100x. So chemical rocket launches would just have to launch components, not fuel. On a large exploration scale, giving that fuel (for fusion) would not be important on the mass budget, asteroid mining could become feasible. And chemical rockets would be "enough" just to launch the initial components, further components would be built from mining materials.

Offline RonM

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Re: Skepticism about reusability
« Reply #18 on: 12/12/2015 04:54 PM »
Does it matter if a reusable FH is twice as massive as a Proton M if the reusable FH flight costs less? I don't think the customer will care.

Reusablity requires trade offs. Loss of capacity for more fuel to return the stage to the launch site is a trade off. If the lower mass to orbit is still enough for the payload, it doesn't matter as long as it is cheaper.

Yeah, it matters.  It matters because the fact that it has to be so much bigger makes it a lot harder for it to end up cheaper.

Note the part of my quoted post I put in bold. Yes, it makes it harder, but if they succeed in making it cheaper per flight than no one will care.

Without some magical technology, a reusable rocket has to be bigger to account for the extra mass that makes it reusable. There's no way around that. Getting back to the OP, that where the skepticism come from.

How much does it cost to stretch a rocket stage?

From what I've seen, the skepticism seems to mainly come from the notion that "an RLV needs high flight rates to be economical." Also, would reusability matter if the labor is in fact the most expensive part of a launch? Here's an argument from a reusability skeptic:

Quote from: Nibb31
Reusability: Cheap spaceflight through reusability has been the holy grail of the aerospace industry since the end of Apollo. SpaceX wasn't the first to envision reusable rockets and won't be the last. The challenge never was technological. It has always been economical. Reusability only makes sense if you have high enough flight rates. Increasing flight rates does not depend solely on bringing costs down. It depends mainly on finding a purpose for those flights.

SpaceX has a high probability of finally achieving first stage recovery and reuse. That will be a great technological accomplishment, but let's remember that the goal isn't to recover or reuse stages, it is to bring costs down. Recovery and reuse do not automatically bring costs down, nor are they the only ways of bringing costs down. Ultimately, what will bring costs down is to increase flight rates in order to generate economies of scale.

Orbital launches are expensive because they employ lots of people to manufacture, test, handle, integrate, transport, and launch the rocket, but also to build payloads and ground stations, integration, fueling, handling, mission planning, mission control... There are also infrastructure costs, administrative overhead costs, facilities, power, IT, HR, training, legal, catering, etc...  The result is hundreds, if not thousands of highly qualified people, working in the aerospace industry. The biggest cost factor is not the first stage hardware, it's the payroll of a particularly expensive workforce. Recovering the first stage is not going to automatically reduce costs by 50% (or even 20%) unless it allows to fire 50% of the workforce. It only has the potential to save some of the manufacturing costs, the rest of the costs remain constant.

SpaceX has invested in facilities that can mass-produce Falcon cores. This means that if reusability comes into full swing, those facilities will be underproducing and the cost of each stage will actually increase due to the lack of economies of scale, which might negate the whole reusability business model.

This is why the competitors of SpaceX (ULA, Airbus, etc.) are in "wait and see" mode. They have their plans to incorporate reusability into their business models if they need to, but they are mainly waiting to see how the market reacts to SpaceX and if SpaceX can actually make reusability profitable before they decide whether it makes economical sense to commit to it.

I agree. That's why people are skeptical.

The TCO (total cost of ownership; materials, factory expenses, manpower, propellant, etc.) of a reusable rocket divided by the number of flights it can make results in its cost per flight. If that cost plus a profit margin turns out to be cheaper than an expendable rocket, then it is a success. It's simple economics, but very difficult engineering.

Offline savuporo

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Re: Skepticism about reusability
« Reply #19 on: 12/12/2015 05:22 PM »
Quote from: Nibb31
Reusability: Cheap spaceflight through reusability has been the holy grail of the aerospace industry since the end of Apollo. SpaceX wasn't the first to envision reusable rockets and won't be the last. The challenge never was technological. It has always been economical. Reusability only makes sense if you have high enough flight rates. Increasing flight rates does not depend solely on bringing costs down. It depends mainly on finding a purpose for those flights.

SpaceX has a high probability of finally achieving first stage recovery and reuse. That will be a great technological accomplishment, but let's remember that the goal isn't to recover or reuse stages, it is to bring costs down. Recovery and reuse do not automatically bring costs down, nor are they the only ways of bringing costs down. Ultimately, what will bring costs down is to increase flight rates in order to generate economies of scale.

Orbital launches are expensive because they employ lots of people to manufacture, test, handle, integrate, transport, and launch the rocket, but also to build payloads and ground stations, integration, fueling, handling, mission planning, mission control... There are also infrastructure costs, administrative overhead costs, facilities, power, IT, HR, training, legal, catering, etc...  The result is hundreds, if not thousands of highly qualified people, working in the aerospace industry. The biggest cost factor is not the first stage hardware, it's the payroll of a particularly expensive workforce. Recovering the first stage is not going to automatically reduce costs by 50% (or even 20%) unless it allows to fire 50% of the workforce. It only has the potential to save some of the manufacturing costs, the rest of the costs remain constant.
Great summary ( which has been re-hashed in so many words on these boards a hundred times ). Re-usability would only be a means to an end to attain higher volumes of activity for the relatively high fixed costs, and only one of the possible means.
There is no practical way to reduce the high fixed costs, spaceflight does and will require many people working on it for the foreseeable future.
Orion - the first and only manned not-too-deep-space craft

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