Spinlaunch... Can it succeed?

[fourfathom]

the laws of physics do apply including the ones the engineers at Spinlaunch overlook and are breaking.

I assume you mean "are trying to break"?  But I've not seen this.  What I have seen is the ignoring of practical physical limits of available materials and available energy.  With enough energy you can certainly launch an unobtanium payload into orbit.  You might create a giant plasma fireball and destroy everything within a ten mile radius, but you could do it.  Doing it practically in a cost-effective manner with a useful payload is another matter, but that's not "Laws of Physics" stuff.

[Rick Law]

the laws of physics do apply including the ones the engineers at Spinlaunch overlook and are breaking.

I assume you mean "are trying to break"?  But I've not seen this.  What I have seen is the ignoring of practical physical limits of available materials and available energy.  With enough energy you can certainly launch an unobtanium payload into orbit.  You might create a giant plasma fireball and destroy everything within a ten mile radius, but you could do it.  Doing it practically in a cost-effective manner with a useful payload is another matter, but that's not "Laws of Physics" stuff.

I agree with the statement above.  Laws of Physics need not be broken.  But to make the economics work out at this time, you would need super-natural intervention.

I actually think we do have consensus on the technology side.  It can work, just expensive.  It is the economic (business viability) side that we have different levels of optimism.

Just to add some details to the rail gun launch power issues:

In my reply (#438) proposing the 300 meter tall vertical rail gun at 917g constant acceleration, the launch vehicle spends 0.2584 seconds inside the rail gun reaching exit velocity at about 2322m/s.

The entire energy budget  has to be dumped into the rail gun in 0.2584 seconds.  Flywheel can't deliver that directly.  The Navy experimental rail gun use Hyper/Ultra capacitors storing the electrical power.  So it would be a two step thing - flywheel or whatever other means as mass energy storage that will be used to charge the capacitor for launch.  Two steps means less efficiency.

[PlainName]

Sure looks to me like they intended on breaking several laws of physics and people who know more about physics see to agree with me.

Exactly which laws of physics are they breaking (or intent on breaking)? Feel free to quote someone who knows more about physics than you if necessary. (But thunderfoot clickbait videos don't count.)

[Nusa]

I'm not a physicist, only took a couple of classes in college. Sure looks to me like they intended on breaking several laws of physics and people who know more about physics see to agree with me.  And you have Thunderf00t who knows more about this stuff, who pointed out several many other issues.

We've had spin launchers for decades, called clay target launchers or skeet throwers.  If it would have been easy and cost effective someone would have built a Spinlancher years ago, but they didn't.

You have people like Elizabeth Holmes who believe anything is possible if enough money is thrown at it and you ignore the science and what the top researchers in that subject area tell you.

If someone has billions to spend on it, let them, it employee people.  I suspect several of the people at Spinlaunch know it can't be done and are happy to take a paycheck from some money guy who never took or failed a physics class.

We seem to have taught a generation All Things Are Possible If You Only Believe.  Which I think stems from
Mark 9:23 — "All things are possible for the one who believes.”

It does not break any laws of physics. Actually its principle of operation is pretty dumb. The questionable part is practicality, not if it can be built as such.

I will disagree.  As several people have posted the laws of physics do apply including the ones the engineers at Spinlaunch overlook and are breaking.

Certainly laws of physics apply. Name just one law of physics that's being broken. Just one, with an applicable example not using made-up facts.

[DougSpindler]

Let me give you one example.  Think of the Gs they are working with.  What material are they going to use for the skin of the satellite and apply the laws of physics and material science.  As they spin the satellite skin closes to the center of rotation will experience a much lessor force that the side furthest from the center of rotation.  Apply the formula F= MV^2/r   Just do the calculations playing around with the r value and the effect it has on the force.  As r increased the F decreases.  At those Gs what material are they going to use which would be strong enough so the skin doesn't wrinkle and tear?  And yet is lightweight to keep costs down.   

https://www.omnicalculator.com/physics/centrifugal-force

I don't think anyone is saying these guy are breaking any laws of nature...  It's more the laws of nature are going to prevent Spinlauch from being a financial success.  Than is unless they break the laws of physics.

[SiliconWizard]

And if/when they fail, we'll be sueing the CEO saying how he lied to everyone and how nobody would have been able to tell.
 

[wraper]

Let me give you one example.  Think of the Gs they are working with.  What material are they going to use for the skin of the satellite and apply the laws of physics and material science.  As they spin the satellite skin closes to the center of rotation will experience a much lessor force that the side furthest from the center of rotation.  Apply the formula F= MV^2/r   Just do the calculations playing around with the r value and the effect it has on the force.  As r increased the F decreases.  At those Gs what material are they going to use which would be strong enough so the skin doesn't wrinkle and tear?  And yet is lightweight to keep costs down.   

https://www.omnicalculator.com/physics/centrifugal-force

I don't think anyone is saying these guy are breaking any laws of nature...  It's more the laws of nature are going to prevent Spinlauch from being a financial success.  Than is unless they break the laws of physics.

Usual Kapton film will survive just fine, especially if reinforced. Weights barely anything and is quite strong. So what if there is 11 thousand G acceleration, I don't see a problem a piece of Kapton film that weights 1g surviving 11kg of load.

[PlainName]

I don't think anyone is saying these guy are breaking any laws of nature...

And yet...

As several people have posted the laws of physics do apply including the ones the engineers at Spinlaunch overlook and are breaking.

[DougSpindler]

Let me give you one example.  Think of the Gs they are working with.  What material are they going to use for the skin of the satellite and apply the laws of physics and material science.  As they spin the satellite skin closes to the center of rotation will experience a much lessor force that the side furthest from the center of rotation.  Apply the formula F= MV^2/r   Just do the calculations playing around with the r value and the effect it has on the force.  As r increased the F decreases.  At those Gs what material are they going to use which would be strong enough so the skin doesn't wrinkle and tear?  And yet is lightweight to keep costs down.   

https://www.omnicalculator.com/physics/centrifugal-force

I don't think anyone is saying these guy are breaking any laws of nature...  It's more the laws of nature are going to prevent Spinlauch from being a financial success.  Than is unless they break the laws of physics.

Usual Kapton film will survive just fine, especially if reinforced. Weights barely anything and is quite strong. So what if there is 11 thousand G acceleration, I don't see a problem a piece of Kapton film that weights 1g surviving 11kg of load.

Never heard of Kapton, but the FAA and NASA sure doesn't seem to like it.  It's use resulted in deaths.  "According to a NASA internal report, space shuttle "wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires."

Many aircraft models have had to undergo extensive rewiring modifications—sometimes completely replacing all the Kapton-insulated wiring—because of short circuits caused by the faulty insulation. Kapton-wire degradation and chafing due to vibration and heat has been implicated in multiple crashes of both fixed wing and rotary wing aircraft, with loss of life.

The forces you say it can withstand are considerably lower that the forces Spinlaunch would subject the skin of the satellite to.  Just do the math, I provided a link to an online calculator so you can see for yourself.

[DougSpindler]

I don't think anyone is saying these guy are breaking any laws of nature...

And yet...

As several people have posted the laws of physics do apply including the ones the engineers at Spinlaunch overlook and are breaking.

If an engineer is not aware of a law in physics does that mean it doesn't apply to them and they can break it?

[PlainName]

1. Which law(s) are they breaking.

2. You said "I don't think anyone is saying these guy are breaking any laws of nature..." but the very same day you had actually said "...including the ones the engineers at Spinlaunch overlook and are breaking". Seems to me you either don't know what you're saying or have a memory issue.

[DougSpindler]

1. Which law(s) are they breaking.

2. You said "I don't think anyone is saying these guy are breaking any laws of nature..." but the very same day you had actually said "...including the ones the engineers at Spinlaunch overlook and are breaking". Seems to me you either don't know what you're saying or have a memory issue.

Materials science in thinking they have a material which can withstand the differential in G forces over the skin of the satellite.  I posted a link to a force calculator.  Can you tell me a substance which will withstand the G forces without damaging the skin of the satellite.  Someone suggested Kapton, which the FAA and NASA has problem with.  But even if if there weren't problems with it, it still doesn't come anywhere close to withstanding the forces of a Spinlaunch.

And no one has been able to offer a solution to prevent the satellite from a precession spin which would result in the satellite tumbling through the atmosphere.  Take a look the the Vertasium video post previously.
   

[Kleinstein]

I don't see the spinlaunch idea is violating a law a nature. For the G forces there still is the option to make it larger to reduce it.

However many things point to significant problems that makes the concept impractical and not economic at all. The main problems mainy have pointed out are:
1) high G force to the paid-load make it rather impractical for most, if not all sattelites. At best is only adds significant weight.
2) the air fraction with the high speed already in the atmosphere causes significant heating and need an additional heat shield, which also adds to the weight.
3) With the added weight chances are that it would no longer be economic.
4) There may not be materials strong enough to build it. The current demonstration gets around 1/10 the required speed / acceleartion and likely already used high grade materials. A simple scale up (e.g. make it 3 times larger) only gives a moderate improvement. To get really faster it would need better materials.

They did some increadible engeniering to reach the speed shown, but this is still far away from being usefull to launch into space.
I don't think the real target is to launch in to space - the main point is getting money based on false promisses. In this aspect they may succeed.

[wraper]

Never heard of Kapton, but the FAA and NASA sure doesn't seem to like it.  It's use resulted in deaths.  "According to a NASA internal report, space shuttle "wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires."

Many aircraft models have had to undergo extensive rewiring modifications—sometimes completely replacing all the Kapton-insulated wiring—because of short circuits caused by the faulty insulation. Kapton-wire degradation and chafing due to vibration and heat has been implicated in multiple crashes of both fixed wing and rotary wing aircraft, with loss of life.

Most of the satellites are covered in multilayer insulation that includes metallized Kapton. That's why they look golden color.

The forces you say it can withstand are considerably lower that the forces Spinlaunch would subject the skin of the satellite to.  Just do the math, I provided a link to an online calculator so you can see for yourself.

"I provided a link to some calculator, therefore it cannot withstand" as you made no calculations whatsoever. I don't need that calculator FFS. I know that Spinlaunch claims 11000G of g-force which I do not need to reinvent. Not to say it does not help in any way to calculate if Kapton film will survive. Kapton spec specifies 69MPa yield point at 3% and 231 MPa Ultimate Tensile Strength https://www.dupont.com/content/dam/dupont/amer/us/en/products/ei-transformation/documents/EI-10142-Kapton-Summary-of-Properties.pdf. So for example we take a 50cm wide square of 25um thick Kapton film. Density is 1.43g/cm³. So let's first calculate how much this square of kapton weights. Volume V=50cm*50cm*25*10^-4(um to cm) = 6.25cm³, m=1.43g/cm³*6.25cm³=8.94g. Then let's assume this piece of kapton is attached only at one side to make calculations easier. Cross section in mm² A = 50*10³(cm to mm)*25*10^-3(um to mm)=1250mm² EDIT: A = 50*10(cm to mm)*25*10^-3(um to mm)=12.50mm². Force F=8.94*9.8(gravity acceleration)*11000(g-force) = 963732N F=8.94*10^-3 (g to kg)*9.8(gravity acceleration)*11000(g-force) = 963.732N.  Calculating tensile stress T=F/A (Tensile Stress = Force / Cross Sectional Area). T=963732N/1250mm2=771MPa T=963.732N/12.50mm²=77MPa. So this this is a bit above yield point (not ultimate tensile strength) but will be just fine if attached at all sides. Using smaller square will reduce tensile stress further. So this would be too much for it. However if we attach it on all 4 sides, it should not rupture, although will elongate beyond reasonable. So using large unsupported patches of it is not the best idea.
But what if we take 20*20cm square. V=20cm*20cm*25*10^-4(um to cm) = 1cm³, m=1.43*1=1.431g. A = 20*10³(cm to mm)*25*10^-3(um to mm)=500mm², F=1*9.8*11000=96800N, T=96800/500= 193.6MPa. So it will not rupture when attached to one side and will be under acceptable stress when attached on all 4 sides.

[DougSpindler]

Never heard of Kapton, but the FAA and NASA sure doesn't seem to like it.  It's use resulted in deaths.  "According to a NASA internal report, space shuttle "wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires."

Many aircraft models have had to undergo extensive rewiring modifications—sometimes completely replacing all the Kapton-insulated wiring—because of short circuits caused by the faulty insulation. Kapton-wire degradation and chafing due to vibration and heat has been implicated in multiple crashes of both fixed wing and rotary wing aircraft, with loss of life.

Most of the satellites are covered in multilayer insulation that includes metallized Kapton. That's why they look golden color.

The forces you say it can withstand are considerably lower that the forces Spinlaunch would subject the skin of the satellite to.  Just do the math, I provided a link to an online calculator so you can see for yourself.

"I provided a link to some calculator, therefore it cannot withstand" as you made no calculations whatsoever. I don't need that calculator FFS. I know that Spinlaunch claims 11000G of g-force which I do not need to reinvent. Not to say it does not help in any way to calculate if Kapton film will survive. Kapton spec specifies 69MPa yield point at 3% and 231 MPa Ultimate Tensile Strength https://www.dupont.com/content/dam/dupont/amer/us/en/products/ei-transformation/documents/EI-10142-Kapton-Summary-of-Properties.pdf. So for example we take a 50cm wide square of 25um thick Kapton film. Density is 1.43g/cm³. So let's first calculate how much this square of kapton weights. Volume V=50cm*50cm*25*10^-4(um to cm) = 6.25cm³, m=1.43g/cm³*6.25cm³=8.94g. Then let's assume this piece of kapton is attached only at one side to make calculations easier. Cross section in mm² A = 50*10³(cm to mm)*25*10^-3(um to mm)=1250mm². Force F=8.94*9.8(gravity acceleration)*11000(g-force) = 963732N. Calculating tensile stress T=F/A (Tensile Stress = Force / Cross Sectional Area). T=963732N/1250mm²=771MPa. So this would be too much for it. However if we attach it on all 4 sides, it should not rupture, although will elongate beyond reasonable. So using large unsupported patches of it is not the best idea.
But what if we take 20*20cm square. V=20cm*20cm*25*10^-4(um to cm) = 1cm³, m=1.43*1=1.431g. A = 20*10³(cm to mm)*25*10^-3(um to mm)=500mm², F=1*9.8*11000=96800N, T=96800/500= 193.6MPa. So it will not rupture when attached to one side and will be under acceptable stress when attached on all 4 sides.

I think you are completely missing my point.  Your calculations are based on the satellite having the force applied equally which is not the case. I've been talking about the differential in F due to the r.

You bring up an interesting issue.  How is Kapton applied?  What prevents the Kapton from delaminating from the surface at those forces?
Is Kapton going to be able to withstand the launch temperatures?
Why is Kapton not used on the outside of jets, rockets and the space shuttle?

[fourfathom]

Jeez, just forget about Kapton, OK?  Say they use Diamond, or Carbon nanotubes, or just general Unobtanium.  Spinlaunch is still a bad idea, and it's not because of Kapton.

[wraper]

I think you are completely missing my point.  Your calculations are based on the satellite having the force applied equally which is not the case. I've been talking about the differential in F due to the r.

While it's not perfect, it shows that existing materials can be used without breaking laws of physics which you claim. As of "differential in F due to the r", force is basically the same over the satellite since it's small compared to the radius of rotation. But even if it's significantly different, so what? For the sake of argument the only thing I'm concerned about is if material will not rupture where the force is maximal. While I don't support Spinlaunch as a project and don't know if it's viable, why should I agree with nonsense arguments against it? The arguments should be based on science and calculations, not on feelings that it cannot possibly work because of reasons. A lot of space related (and other) science is very counterintuitive. Spacex was a laughing stock for the industry with their rocket landing claims, many experts said it's impossible. Until nobody laughed anymore.

You bring up an interesting issue.  How is Kapton applied?  What prevents the Kapton from delaminating from the surface at those forces?

My calculations are about a piece of it which is fixed only on the edge(s) without gluing it to anything. So for example fixed by clamps if you are concerned about delamination. In any case argument was about if there is material which can survive acceleration, not how it should be implemented in practice.

Is Kapton going to be able to withstand the launch temperatures?

Kapton will survive a few hundred ^oC just fine. Rocket is supposed to be out of atmosphere very fast, way before payload can heat up. And once out of atmosphere, hot fairing will be separated an no longer be of a concern.

Why is Kapton not used on the outside of jets, rockets and the space shuttle?

Because there is no reason to use it. Satellites do not fly through the atmosphere, different materials are better suitable for different purposes. Kapton works really well over a wide range of temperatures from almost absolute zero to about 400^oC. Again, this was just a ballpark calculation to show that a traditional material can be used without breaking physics.

[wraper]

Jeez, just forget about Kapton, OK?  Say they use Diamond, or Carbon nanotubes, or just general Unobtanium.  Spinlaunch is still a bad idea, and it's not because of Kapton.

The argument was about breaking the laws of physics. I can intuitively feel that a lot of ideas are bad but it does not prove anything. Only if it's shown by actual numbers that it cannot possibly work, then I can be certain it never will.

[wraper]

Actually just noticed my calculation had errors while converting units. Both in favor of spinlaunch and against it but overall making things worse for it 10 times. Very hot days here so my head does not work the best.

[DougSpindler]

I think you are completely missing my point.  Your calculations are based on the satellite having the force applied equally which is not the case. I've been talking about the differential in F due to the r.

While it's not perfect, it shows that existing materials can be used without breaking laws of physics which you claim. As of "differential in F due to the r", force is basically the same over the satellite since it's small compared to the radius of rotation. But even if it's significantly different, so what? For the sake of argument the only thing I'm concerned about is if material will not rupture where the force is maximal. While I don't support Spinlaunch as a project and don't know if it's viable, why should I agree with nonsense arguments against it? The arguments should be based on science and calculations, not on feelings that it cannot possibly work because of reasons. A lot of space related (and other) science is very counterintuitive. Spacex was a laughing stock for the industry with their rocket landing claims, many experts said it's impossible. Until nobody laughed anymore.

You bring up an interesting issue.  How is Kapton applied?  What prevents the Kapton from delaminating from the surface at those forces?

My calculations are about a piece of it which is fixed only on the edge(s) without gluing it to anything. So for example fixed by clamps if you are concerned about delamination. In any case argument was about if there is material which can survive acceleration, not how it should be implemented in practice.

Is Kapton going to be able to withstand the launch temperatures?

Kapton will survive a few hundred ^oC just fine. Rocket is supposed to be out of atmosphere very fast, way before payload can heat up. And once out of atmosphere, hot fairing will be separated an no longer be of a concern.

Why is Kapton not used on the outside of jets, rockets and the space shuttle?

Because there is no reason to use it. Satellites do not fly through the atmosphere, different materials are better suitable for different purposes. Kapton works really well over a wide range of temperatures from almost absolute zero to about 400^oC. Again, this was just a ballpark calculation to show that a traditional material can be used without breaking physics.

You are thinking on the macro-level and not the material science level.  I just don't see how traditional materials could withstand the forces without buckling    Even if wrapped in Kapton sock, which I don't think would withstand the temperatures how is the Kapton going to be bonded securely to affixed to the skin to prevent skink for scratching and compressing.  You might want to apply Euler's critical load and Johnson's parabolic formula and see what the results are.  Just look at the force differential when using two values for r representing the width of the satellite.

[Nusa]

I don't even have to do the math to know that force vectors (centrifugal and rotational) add, and you merely have to design the payload to resist in the resulting single direction. You're chasing a non-problem.

And you still haven't stated a Physics law that is being broken. Or are you now willing to admit that nobody is trying to break Physics?

[CatalinaWOW]

Doug Spindler, just what do you think the force differential is?  The equation is dirt simple, acceleration equals angular velocity squared times radius.  I haven't gone through the papers to see what the flinger arm length is, but based on the launch velocities and accelerations mentioned it is on the order of 20 meters.   Even assuming a payload diameter of 1 meter, which is quite large for this concept the delta radius is only about 5%.  Or around a 500 g.  That is a big number, but negligible compared to the base number.  If it can survive hanging on the end of the flinger with any safety margin at all it will survive the differential loads.

[DougSpindler]

If you are correct, it’s a non-issue.
As I have stated many time it will be interesting to see if they can overcome all of the technical issues.  Only money and time will tell.

[StillTrying]

The laws of physics probably won't break, just everything else.

[SiliconWizard]

Only money and time will tell.

That's the beauty of it!