Author Topic: Upgrading rocket materials  (Read 31415 times)

Offline Ludus

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Re: Upgrading rocket materials
« Reply #20 on: 01/30/2016 11:17 pm »
In the next few years if reusability works well SX needs to pivot Hawthorne to making more second stages and vacuum merlins and fewer first stages, as much as possible repurposing the same facilities and employees to the new product mix. If they can pull that off efficiently they can substitute reused stages profitably and do more launches at lower cost.

They benefit from the commonalities they designed in between first and second stages and vertical integration. For awhile it's an advantage that they build reusable and expendable the same way.

Offline Port

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Re: Upgrading rocket materials
« Reply #21 on: 01/30/2016 11:54 pm »
nanotubes are strong at a nano-scale (measured from end to end) but this property is not easily transferred by mixing them into the material you want to have the desired boost in whatever it is you want

best example for that are carbon nanotubes:
mixing nanotubes into a polymer to increase it's strength - gain of 2% in E-modul for enormous costs while the tube itself would have on the order of 10x of the achieved value
it's simply not useful when you can achieve the same or better results with conventional methods that also are much cheaper

Offline sanman

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Re: Upgrading rocket materials
« Reply #22 on: 01/31/2016 04:21 pm »
Sure, the nanotube-matrix interface is known to be the weak part, but researchers have been looking into remedies for it. Functionalization of nanotubes, possibly using fluorochemistry is one option. Also, the longer the nanotubes are, the larger their Van Der Waals forces for adhesion to a surrounding matrix. Furthermore, Boron Nitride nanotubes are based on the -B-N- unit, which itself has a polarity that can also be exploited for adhesion to the surrounding matrix.
Attempts have been made to helicalize nanotubes, so that they aren't completely straight, since a helical conformation again creates more shear resistance, rather than them slipping straight through a matrix.

Offline Robotbeat

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Re: Upgrading rocket materials
« Reply #23 on: 01/31/2016 06:02 pm »
Boron nitride sucks much worse than carbon nanotubes. Nobody has made a usefully strong boron nitride nanotube macroscopic fiber. Don't believe the hype.

At least people have started to make some useful carbon nanotube fibers, with a specific strength of up to 2GPa/(g/cc) (though more like 1.6 in long lengths... Good enough to make things out of.) that's still not as good as the 3.6GPa/(g/cc) you can get with state of the art Zylon or T1100G carbon fiber, but it's just as good as your typical IM7, and it is still improving.

If you want to make something with really high specific weight right now, use Zylon or T1100G. I would lean toward Zylon because it works well in flexible fabric form (as well as a stiff composite), but carbon fiber doesn't like to be bent like that.
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Offline Roga

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Re: Upgrading rocket materials
« Reply #24 on: 02/05/2016 03:17 am »
I guess the notion here is that if you are going to use a stage forty times, materials that cost ten times as much and weigh less, or are more durable, might start to make economic sense.

Matthew

Conversely, there would be pressure to drive down the cost of the second stage and fairings if they continue to expend them. That's much harder to do with design since 1) second stages tend to push mass efficiency to the limit, and 2) the bulk of the cost is likely in the engine which would be just as optimized as the stage due to the need for high ISP. However I could see the manufacturing processes diverge rather sharply, whereas now they use a lot of the same tooling, materials, and components.

At the very least it seems like Stage 2 would become the pathfinder for new production process improvements. Stage 1 then becomes the pathfinder for novel technologies, with the added advantage that you can get them back for examination after some operational exposure.

The alternative is to go the ULA route and make Stage 2 a legit spaceship, where you can add more value on orbit.

Offline sanman

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Re: Upgrading rocket materials
« Reply #25 on: 02/09/2016 03:57 am »
Graphene is supposed to be another very promising wonder material. It has a tensile strength which exceeds that of carbon nanotubes, and is also known to have useful electronic properties, including good thermal conductivity.

Another thing is that graphene is notoriously impermeable to all molecules, including even hydrogen.

Perhaps it could make very strong parachutes in the future, or prevent atmosphere from escaping from your spacesuit. Or perhaps improved electronics.


Offline dror

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Re: Upgrading rocket materials
« Reply #26 on: 02/24/2016 05:48 pm »
Since they can begin to expect to recover engines and stages, and they can potentially spend more on each unit of the first stage and the next merlins, what types of more expensive materials might be used in F9 1.3?

In this thread:
http://forum.nasaspaceflight.com/index.php?topic=35533.msg1249705#msg1249705
Hyperion5 and Dimitry suggested AL2050 -
"The hypothetical family was to be the same exact physical size as its kerolox cousins to make its use with existing Spacex pads more feasible.  The only major changes were the use of AL-2050 (to maximize the performance dividend), dimensions of the propellant tanks, insulation levels, and the 10 engines attached."

I wondered how much of the performance gain they suggested was due to this change.
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Offline TomH

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Re: Upgrading rocket materials
« Reply #27 on: 02/24/2016 07:50 pm »
carbon fiber doesn't like to be bent like that.

Graphene is supposed to be another very promising wonder material. It has a tensile strength which exceeds that of carbon nanotubes

Graphene is carbon laid out in a crystalline structure one atom thick. It can be layered in laminate form, but does it suffer from the same thing Robotbeat says about carbon fiber? Is it flexible, or will the bonds break in those one atom thick planes if flexed?

Offline sanman

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Re: Upgrading rocket materials
« Reply #28 on: 02/25/2016 06:00 am »
Graphene is carbon laid out in a crystalline structure one atom thick. It can be layered in laminate form, but does it suffer from the same thing Robotbeat says about carbon fiber? Is it flexible, or will the bonds break in those one atom thick planes if flexed?


Each individual graphene sheet is quite strong, but the weakness would be in the adhesion between the layers, which are only due to Van der Waals forces, or in the adhesion of the sheets to any surrounding matrix. But again, functionalization of the sheets would probably address this.
Another thing is that large sheets of graphene would have to be grown defect-free, since you're only a strong as your weakest spot.

Don't forget that graphene is very electrically conductive as well, so graphene nanoribbons have electronics uses too.


Meanwhile, Musk seems to have hired Apple's former head of materials engineering, to work for both SpaceX and Tesla:

http://9to5mac.com/2016/02/24/apple-alloy-kuehmann-musk-tesla-spacex/

I wonder if he has any particularly interesting materials in mind?

Offline john smith 19

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Re: Upgrading rocket materials
« Reply #29 on: 02/25/2016 02:23 pm »

Conversely, there would be pressure to drive down the cost of the second stage and fairings if they continue to expend them. That's much harder to do with design since 1) second stages tend to push mass efficiency to the limit, and 2) the bulk of the cost is likely in the engine which would be just as optimized as the stage due to the need for high ISP. However I could see the manufacturing processes diverge rather sharply, whereas now they use a lot of the same tooling, materials, and components.
Yes that's pretty much the strategy of design-for-minimum-cost.  Scaling the technology level to the stage.

Trouble is to do so you're into another big development programme with large NRE costs.

This route leads to composite tanks, sub cooled propellants and a raptor.

Some people seem to think some of that will happen. Time will tell.
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Offline Robotbeat

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Re: Upgrading rocket materials
« Reply #30 on: 02/28/2016 04:22 am »
carbon fiber doesn't like to be bent like that.

Graphene is supposed to be another very promising wonder material. It has a tensile strength which exceeds that of carbon nanotubes

Graphene is carbon laid out in a crystalline structure one atom thick. It can be layered in laminate form, but does it suffer from the same thing Robotbeat says about carbon fiber? Is it flexible, or will the bonds break in those one atom thick planes if flexed?
Graphene and carbon nanotubes are basically the same thing. Carbon nanotubes are just rolled up graphene.

Heck, carbon fiber looks a lot like graphene and nanotube at the atomic level, i.e. the nearest, say, 100 atoms.

Graphene also is also weak so far at the macroscopic level, though perhaps it has improved some.

A lot of all this is just getting sufficient purity and crystallinity, and perhaps getting some better interlinking.

But you can make carbon nanotube stuff pretty tough. Carbon fiber is brittle because it's made out of PAN fibers that are pretty wide, whereas nanotubes are much smaller, so there's more room for shifting and energy absorption.

But really, there are still advancements being made in carbon fiber, though slower. A lot of the work is in getting our existing academic tools for modeling and damage tolerance calculations integrated into actual industry use so that carbon fiber can be fully taken advantage of, instead of huge factors of safety lathered on unnecessarily, simply because the right modeling tools are not available.
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Offline R7

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Re: Upgrading rocket materials
« Reply #31 on: 03/07/2016 12:36 pm »
Recently, a new stainless magnesium-lithium alloy was discovered that weighs half as much as aluminium.

Density alone doesn't say much about how good an alloy is. Strength alone neither. Strength divided by density aka specific strength, now that's something one should look for.

Specific strength of Mg-Li alloys has been moderate at best.

Then there are flammability issues, properties at cryogenic temp (brittleness), compatability with contained fluids and so on.
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Offline JasonAW3

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Re: Upgrading rocket materials
« Reply #32 on: 05/16/2016 03:44 pm »
Recently, a new stainless magnesium-lithium alloy was discovered that weighs half as much as aluminium.

See also:   http://www.gizmag.com/corrosion-resistant-magnesium-alloy/40600/

If it's possible for SpaceX to apply this new alloy, their rockets might gain tons and tons of extra payload capability just by making the first and second stage bodies from that alloy. I don't know if this specific material could qualify for rocketry, but it might well be worth testing this.

To be on the safe side, they might try and use an innovative sandwich material with two 'traditional' relatively thin inner and outer metal sheets layers, and one appropriately thick MgLi alloy bulk layer to shave off perhaps 1000s of kg of the stage bodies.

Yeah, not really too certain about this idea.  Both Lithium and Magnesium have a fairly low melting/burning point.  You'd likely wind up adding more mass to thermal protect the structure than you would in reducing the mass.
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Offline sanman

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Re: Upgrading rocket materials
« Reply #33 on: 05/30/2016 04:39 am »
Why can't they put a diamond coating onto the X-wing grid fins to keep them from smoking/burning up during the re-entry?

Offline Semmel

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Re: Upgrading rocket materials
« Reply #34 on: 05/30/2016 06:14 am »
Diamonds burn pretty easily compared to other material..

Online mikes

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Re: Upgrading rocket materials
« Reply #35 on: 05/30/2016 08:01 am »
Diamonds burn pretty easily compared to other material..
Yup, burns nicely provided there's sufficient oxygen


The grid fins seem a good candidate for regarding as a consumable to be replaced for reflight. They're not complex and (unless they're made of something exotic) unlikely to cost a lot.

Offline rocx

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Re: Upgrading rocket materials
« Reply #36 on: 05/30/2016 08:04 am »
Diamonds burn pretty easily compared to other material..

So it turns out, diamonds are not forever.
Any day with a rocket landing is a fantastic day.

Offline mvpel

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Re: Upgrading rocket materials
« Reply #37 on: 05/30/2016 04:15 pm »
Diamond ignition temperature in air is about 900C, and begins to erode at about 700C. Would that be enough for reentry heating? It's also an excellent conductor of heat - five times better than copper - which enabled a 3x increase in power density for Raytheon's GaN-based radar equipment. Raytheon: Inside the Diamond Mine: Synthetic Gems

The CVD Diamond Booklet - Chapter 3 has thermal properties
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Offline M_Puckett

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Re: Upgrading rocket materials
« Reply #38 on: 06/01/2016 01:33 pm »
Why would they need to change materials?

If you are not throwing it away and can get say a couple dozen uses, optimizations start to make economic sense.

Offline mvpel

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Re: Upgrading rocket materials
« Reply #39 on: 06/02/2016 12:19 am »
Titanium grid fins for supersonic rocket manufactured

Quote from: LIN Industrial
3D printed plastic grid fins we currently use can't withstand the dynamic pressure and heating at supersonic. That's why we have started manufacturing titanium grid fins. They are cut from a single piece of titanium with a CNC machine:

"Ugly programs are like ugly suspension bridges: they're much more liable to collapse than pretty ones, because the way humans (especially engineer-humans) perceive beauty is intimately related to our ability to process and understand complexity. A language that makes it hard to write elegant code makes it hard to write good code." - Eric S. Raymond

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