Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2101331 times)

Offline AnalogMan

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Perhaps a more general solution to the problem of melting nylon bolts would be to search diligently for a material that does not melt.

While perhaps more difficult to obtain (read that as "custom manufacture") bolts can be made from almost any solid. I can just imagine Paul with his pen-knife carving a bolt from a wooden dowel rod. Or baking a ceramic bolt in this wife's kitchen oven.

Seriously though, the bolts problem is a materials issue. What are the necessary characteristics of the bolts, then what are the various materials that satisfy those specifications?

Now that we know the specifications, who wants to volunteer to make 4 bolts?

Edit Add: Or maybe there exists an epoxy (glue) that would serve to attach the dielectric disks?

You can buy ceramic machine screws/bolts/nuts (if you can afford them!)

(for example: http://www.amazon.com/Ceramic-Machine-Finish-External-Threads/dp/B00DD44VPA)
« Last Edit: 02/22/2015 03:07 PM by AnalogMan »

Offline Rodal

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Please take into account, that as Paul March (@Star-Drive) stated:

the nylon bolts themselves could be contributing to the measured force we are seeing?  It has a much smaller volume than the PE and PTFE discs, but they have a much higher dissipation factor than PE or PTFE that could translate into more work done converting E&M momentum into mechanical forces.

Hence using ceramic bolts (if their cost can be afforded) could provide a straightforward way to test this possibility.
« Last Edit: 02/22/2015 03:23 PM by Rodal »

Offline Star-Drive

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All:

I tried epoxy and superglue bonding the PE and PTFE discs to the frustum end-caps, but these two plastics just happen to be the slickest and hardest plastics to bond to anything else.  Drat!  And yes I tried to find aluminum oxide or other low-loss dielectric ceramics bolts & nuts in long enough lengths (~2.50") to work in my application with no luck, but I'll admit I didn't look very hard at the time for I had many other things to do.

Aero: I'm not going to start carving out bolts from wood dowels! :)  But that does make me wonder if any wood would have a low enough dissipation factor at 2.0 GHz to be useable...  So many things to think about... 

Best,  Paul M.
Star-Drive

Offline Rodal

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All:

I tried epoxy and superglue bonding the PE and PTFE discs to the frustum end-caps, but these two plastics just happen to be the slickest and hardest plastics to bond to anything else.  Drat!  And yes I tried to find aluminum oxide or other low-loss dielectric ceramics bolts & nuts in long enough lengths (~2.50") to work in my application with no luck, but I'll admit I didn't look very hard at the time for I had many other things to do.

Aero: I'm not going to start carving out bolts from wood dowels! :)  But that does make me wonder if any wood would have a low enough dissipation factor at 2.0 GHz to be useable...  So many things to think about... 

Best,  Paul M.

Concerning using an adhesive to adhere the HD PE to the copper,yes,  Polyolefin polymers in general are the most common type of hard to bond plastics because of their low surface energy.  HD PE is a Polyolefin polymer and hence hard to bond to due to its low surface energy.  Adhesion would involve surface preparation techniques as well.  Adhesion of copper to HD PE would involve: temperature, humidity, fixture time, chemicals (sometimes carcinogenic ones, particularly for the solvent primer), they can be messy. 

Most importantly, the adhesion would be permanent and removing the dielectric from the copper base plate would involve damage.

Surface roughening of the copper and of the HD PE results in mechanical interlocking sites and causes bond
strength to increase dramatically. A surface roughness of approximately 60-125 microinches is often used as a guideline for assemblies that are to be bonded with adhesives.  Shotblasting of the copper surface is usually needed.  This is an insurmountable problem for your extremely thin copper surface: there is practically no thickness of copper on the fiber-reinforced flat end to be able to roughen the copper.

Primers are solvent-based systems in which a reactive species is dissolved. Applied to a surface using a brush or spray, the primers solvent evaporates, leaving behind the reactive species on the substrate. The reactive species acts as a linking pin or bridge between an adhesive and the substrate Polyolefin primers are frequently used on hard-to-bond substrates joined with traditional and/or light curing cyanoacrylates.

Paul, I have experience with bonding hard to bond polymers, it can be done successfully, but it is not trivial, as you have also experienced.  This combined with the permanent nature of an adhesive, would also lead me to seek bolt alternatives, particularly for an R&D effort were you are going to have to dismantle, disassemble  and reconfigure your setup from time to time.
« Last Edit: 02/22/2015 03:42 PM by Rodal »

Offline Dagger

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What about Vespel Bolts? Temperature resistant up to 288C (350F) continuous and 480C (900F) intermittent.

These guys at Extreme Bolt & Fastener can custom make it:
http://www.extreme-bolt.com/Products-PI-Bolts.html

They can also custom make ceramic bolts.

Online flux_capacitor

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Surface roughening of the copper and of the HD PE results in mechanical interlocking sites and causes bond
strength to increase dramatically. A surface roughness of approximately 60-125 microinches is often used as a guideline for assemblies that are to be bonded with adhesives.  Shotblasting of the copper surface is usually needed.  This is an insurmountable problem for your extremely thin copper surface: there is practically no thickness of copper on the fiber-reinforced flat end to be able to roughen the copper.

I see another problem apart from the wall being too thin: wouldn't roughening the internal face of the small copper plate (in order for the glue to stick better) dramatically decrease its reflecting capacity, hence the Q factor of the cavity?

Paul, I have experience with bonding hard to bond polymers, it can be done successfully, but it is not trivial, as you have also experienced.  This combined with the permanent nature of an adhesive, would also lead me to seek bolt alternatives, particularly for an R&D effort were you are going to have to dismantle, disassemble  and reconfigure your setup from time to time.

The beauty of this copper cavity lays in its extreme versatility. It's not a superconducting cavity machined from one piece of expensive material. The small end plate is just that: a thin copper plate, with a diameter of a few inches, attached to the end of the body with bolts at rim. Although I think like you that bolts would be better than glue to attach the internal dielectric, I also think even Eagleworks could afford several end plates, and test them for comparison: one small plate without any dielectric at all, one with a dielectric bonded with some glue as you suggested, another one fixed with bolts of any type, etc.
« Last Edit: 02/22/2015 04:02 PM by flux_capacitor »

Offline Notsosureofit

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If you would like I can sputter coat the mating surface to the end plate w/ copper (or something that would make it easier to adhesive bond).  Only cost you the postage.....

Offline frobnicat

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Do the screws to fix the dielectric inside the frustum go through the end PCB plate ?

In this case, even if the hole in the copper is much smaller than the wavelength (in nylon ?), wouldn't that allow a significant amount of em energy to escape and bounce around between the frustum and vacuum chamber walls ? Aero's simulation with Meep seemed to say that evanescent waves could funnel through much thinner cracks, if not to let escape real travelling photons at least for near field interactions with things outside the frustum...

Offline zen-in

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All:

I tried epoxy and superglue bonding the PE and PTFE discs to the frustum end-caps, but these two plastics just happen to be the slickest and hardest plastics to bond to anything else.  Drat!  And yes I tried to find aluminum oxide or other low-loss dielectric ceramics bolts & nuts in long enough lengths (~2.50") to work in my application with no luck, but I'll admit I didn't look very hard at the time for I had many other things to do.

Aero: I'm not going to start carving out bolts from wood dowels! :)  But that does make me wonder if any wood would have a low enough dissipation factor at 2.0 GHz to be useable...  So many things to think about... 

Best,  Paul M.

The marine adhesive made by 3M  (5200 or 5220 fast cure) will stick to anything; even under water.   I have used it on HDP.  Most adhesives will just drop off once they have cured.   One trick I learned for gauging the dissipation factor of a plastic is to put it in a microwave oven at high power for 10 minutes; or less.  But I think the problem you are seeing is not from the dissipation factor of the plastic because your power level is relatively low.  Try putting one of the nylon bolts in a microwave and see if it melts.   What may be happening is the thin Copper coating is getting very hot and melting the nylon bolt.   The radiation pattern from the loop antenna inside the cavity directs most of the rf power to the large  end, irrespective of the mode.
« Last Edit: 02/22/2015 05:00 PM by zen-in »

Offline RotoSequence

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Do the screws to fix the dielectric inside the frustum go through the end PCB plate ?

In this case, even if the hole in the copper is much smaller than the wavelength (in nylon ?), wouldn't that allow a significant amount of em energy to escape and bounce around between the frustum and vacuum chamber walls ? Aero's simulation with Meep seemed to say that evanescent waves could funnel through much thinner cracks, if not to let escape real travelling photons at least for near field interactions with things outside the frustum...

Assuming something similar hasn't been done already, it should be possible to test for photon emissions by shortening the nylon bolts and securing the outside ends with cap nuts.

« Last Edit: 02/22/2015 05:15 PM by RotoSequence »

Offline wembley

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... then many scientists tried to replicate their experiment but hopes fell with the large number of negative replications, and the withdrawal of many positive replications.

Sad but true.  There is, however, somewhat of a renaissance occurring right now with LENR+ (commercially viable LENR).  The current most promising method uses a mixture of nickel powder, iron powder, and LiAlH4 heated to 1100 C under pressure.  Multiple universities in the U.S. have recently opened programs with full funding to investigate LENR+.  Don't count this phenomena out entirely.  Coupled with an EM Drive, the space flight applications become very interesting.  Admittedly, controversy abounds, and it is still early to say what the probability of success and implications might be, but nonetheless, it doesn't hurt to keep a finger on the pulse on the most current efforts underway.

Amusingly enough, some of the LENR work is taking place at NASA -- in a very low-level, part-time-project fashion.

The comparisons between developments in the two are quite striking -- mainstream skepticism, lack of a solid theoretical base, amazing claims by one-man-show inventors, and steady drip-feed of 'anomalous' results. Which of course, doesn't mean that either is real.

Offline Star-Drive

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If you would like I can sputter coat the mating surface to the end plate w/ copper (or something that would make it easier to adhesive bond).  Only cost you the postage.....

Notsosureofit:

Send me a private note with your name and address and I'll gladly send you a PE and PTFE disc to have them sputter copper coated on one flat side only in your lab.  When returned we can then silver epoxy or even Pb/Sn solder the discs to a new set of 0.090" thick small OD copper end-caps we have sitting in the lab.  And thanks much for the offer!

Best, Paul M.
« Last Edit: 02/22/2015 07:20 PM by Star-Drive »
Star-Drive

Offline Star-Drive

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I tried epoxy and superglue bonding the PE and PTFE discs to the frustum end-caps, but these two plastics just happen to be the slickest and hardest plastics to bond to anything else.  Drat!  And yes I tried to find aluminum oxide or other low-loss dielectric ceramics bolts & nuts in long enough lengths (~2.50") to work in my application with no luck, but I'll admit I didn't look very hard at the time for I had many other things to do.

Aero: I'm not going to start carving out bolts from wood dowels! :)  But that does make me wonder if any wood would have a low enough dissipation factor at 2.0 GHz to be useable...  So many things to think about... 

Best,  Paul M.

The marine adhesive made by 3M  (5200 or 5220 fast cure) will stick to anything; even under water.   I have used it on HDP.  Most adhesives will just drop off once they have cured.   One trick I learned for gauging the dissipation factor of a plastic is to put it in a microwave oven at high power for 10 minutes; or less.  But I think the problem you are seeing is not from the dissipation factor of the plastic because your power level is relatively low.  Try putting one of the nylon bolts in a microwave and see if it melts.   What may be happening is the thin Copper coating is getting very hot and melting the nylon bolt.   The radiation pattern from the loop antenna inside the cavity directs most of the rf power to the large  end, irrespective of the mode.

Zen-In:

Thanks for the recommendation and I'll give this 3M marine adhesive a try to see how it might work with difficult to bond plastics like PE and PTFE, hopefully without ALL the preparation outlined by Rodal.

Best, Paul, M.
Star-Drive

Online Mulletron

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http://www.tara.tcd.ie/handle/2262/38886
http://www.ncbi.nlm.nih.gov/pubmed/16711970
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.96.130402

Quote
A recent publication [Phys. Rev. Lett. 92, 020404 (2004)PRLTAO0031-900710. 1103/PhysRevLett.92.020404] raises the possibility of momentum transfer from zero-point quantum fluctuations to matter, controlled by applied electric and magnetic fields. We present a Lorentz-invariant description using field-theoretical regularization techniques. We find no momentum transfer for homogeneous media, but predict a very small transfer for a Casimir-type geometry.

An oldie but goodie. These are the older papers. Note the bold part.

I bet that having those PE discs smashed up against each other and the copper is important! From what Paul reported, it is. Here's why I think so:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329454#msg1329454
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329531#msg1329531
Quoting me.
Quote
About half the time when I think this through, the darn thing thrusts backwards.

Quoting @Paul March http://forum.nasaspaceflight.com/index.php?topic=36313.msg1335190#msg1335190
Quote
.....it was producing less than half of what it did before and in the wrong direction!......Apparently not having the PE discs firmly mounted to the frustum's small OD end cap hindered the thrust producing mechanism that conveys the generated forces in the PE to the copper frustum.

Paul, would you be willing to introduce a small gap between the copper and PE as a test? Like tighten down the Nylon bolts and wedge a wooden shim in there?
Also, I know this is kinda high speed, but do you have any gold leaf? To wedge between the PE and Copper? http://en.wikipedia.org/wiki/Gold_leaf#Culinary_uses
The reason I'm saying all this is, if we're gonna call these things Quantum Vacuum thrusters, we need to treat it like a Casimir experiment, instead of a plasma thruster.

Break:
IRT the new stuff I've been posting about PT symmetry, this is a nice plain english rundown of how it works from different people, saying the same thing as the other researchers.
http://www.lap.physik.uni-erlangen.de/lap/?page=research_krstic_chiral&language=en (Also see those references at the bottom, this is very exciting stuff. I think I may actually be right on this one ;) )

And onto the subject of the Nylon bolts:
So there's a bunch of different types of nylon. Anyone know what kind of nylon those bolts might be made of? Wouldn't it be something if nylon was doing some of the thrusting the whole time.
Is it these? http://www.mcmaster.com/#nylon-6/6-screws/=w0xvlx

I feel really goofy right now holding a mirror up to the computer screen.
« Last Edit: 02/22/2015 11:04 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Online Mulletron

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@ Star-Drive

We've battled the Nylon vs Teflon fasteners for years in our plasma chambers.  These days we replace the Nylon ones every run.  Teflon holds up very well, just won't take much mechanical load.

Notsosureofit:

We've fried a number of nylon bolts and have found that the best way to keep them from getting cooked is to keep them out of the high E-field regions in the cavity.  For Instance we tested the copper frustum in its TM010 mode and mounted a 5.0 inch OD by 1.0" thick PTFE disk at the center of the large OD end cap of the copper frustum with one 1/4-20 nylon bolt.  We got some large thrust signatures in that configuration, see attached slide, but the dam nylon bolt kept melting and dropping the PTFE discs into the main body of the cavity.  Brother did that look like a magnitude 9 earthquake on our uN resolution force measurement system! 

That said, I'm wondering if the nylon bolts themselves could be contributing to the measured force we are seeing?  It has a much smaller volume than the PE and PTFE discs, but they have a much higher dissipation factor than PE or PTFE that could translate into more work done converting E&M momentum into mechanical forces.

Best, Paul M.

Look at the Comsol plot of TM010 with PTFE at large end showing large thrust. Note the strong magnetic field in that region. Do I need to bring Colbert back again?  ;)
« Last Edit: 02/22/2015 11:01 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Star-Drive

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http://www.tara.tcd.ie/handle/2262/38886
http://www.ncbi.nlm.nih.gov/pubmed/16711970
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.96.130402

Quote
A recent publication [Phys. Rev. Lett. 92, 020404 (2004)PRLTAO0031-900710. 1103/PhysRevLett.92.020404] raises the possibility of momentum transfer from zero-point quantum fluctuations to matter, controlled by applied electric and magnetic fields. We present a Lorentz-invariant description using field-theoretical regularization techniques. We find no momentum transfer for homogeneous media, but predict a very small transfer for a Casimir-type geometry.

An oldie but goodie. These are the older papers. Note the bold part.

I bet that having those PE discs smashed up against each other and the copper is important! From what Paul reported, it is. Here's why I think so:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329454#msg1329454
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329531#msg1329531
Quoting me.
Quote
About half the time when I think this through, the darn thing thrusts backwards.

Quoting @Paul March http://forum.nasaspaceflight.com/index.php?topic=36313.msg1335190#msg1335190
Quote
.....it was producing less than half of what it did before and in the wrong direction!......Apparently not having the PE discs firmly mounted to the frustum's small OD end cap hindered the thrust producing mechanism that conveys the generated forces in the PE to the copper frustum.

Paul, would you be willing to introduce a small gap between the copper and PE as a test? Like tighten down the Nylon bolts and wedge a wooden shim in there?
Also, I know this is kinda high speed, but do you have any gold leaf? To wedge between the PE and Copper? http://en.wikipedia.org/wiki/Gold_leaf#Culinary_uses
The reason I'm saying all this is, if we're gonna call these things Quantum Vacuum thrusters, we need to treat it like a Casimir experiment, instead of a plasma thruster.

Break:
IRT the new stuff I've been posting about PT symmetry, this is a nice plain english rundown of how it works from different people, saying the same thing as the other researchers.
http://www.lap.physik.uni-erlangen.de/lap/?page=research_krstic_chiral&language=en (Also see those references at the bottom, this is very exciting stuff. I think I may actually be right on this one ;) )

And onto the subject of the Nylon bolts:
So there's a bunch of different types of nylon. Anyone know what kind of nylon those bolts might be made of? Wouldn't it be something if nylon was doing some of the thrusting the whole time.

I feel really goofy right now holding a mirror up to the computer screen.

Mulletron:

Treat this thing as a large collection of Casimir Cavities, might work if I can convince Dr. White to do so, and only after we both read through your referenced papers on the topic.  And oh yes, get to Glenn Research Center for a successful replication of what we've seen to date before the end of March, or I may find myself in retirement before I was ready...

As to the source of my nylon cap screws it is http://www.mcmaster.com/#nylon-cap-screws/=w0xvi2.  As to what plastics vendor they use for their nylon supplier and what type of nylon is used in their cap-screws and bolts is TBD.

PS: How big a gap are you thinking about between the PE and copper plate?  Microns or mm...??

Best,  Paul M.     
« Last Edit: 02/22/2015 11:20 PM by Star-Drive »
Star-Drive

Online Mulletron

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Just a few mm on one side, like what you get from a spudger tip. To be clear, the gap is intended to break the thrust. From what you're saying, it would break the thrust. It serves to provide a clear answer whether Casimir forces play any part in the thrust or not, or if the PT momentum transfer/anisotropic vacuum idea is enough.

What I picture going on is that the Casimir forces at the PE/air/copper interface isn't the sole enabler of thrust, it is a major amplifying feature of the thrust.

Let's say that there is a few mm gap between the PE and the copper all around. If that breaks the thrust, then it is clear Casimir forces are important.


Well anyway, this is neat to watch. https://nanohub.org/resources/21370/watch?resid=21371
« Last Edit: 02/23/2015 01:09 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Rodal

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....

Treat this thing as a large collection of Casimir Cavities, might work if I can convince Dr. White to do so, and only after we both read through your referenced papers on the topic.  And oh yes, get to Glenn Research Center for a successful replication of what we've seen to date before the end of March, or I may find myself in retirement before I was ready...

..

I put the emphasis on:

 get to Glenn Research Center for a successful replication of what we've seen to date before the end of March, or I may find myself in retirement

That would be a horrible waste of human talent and experience, somebody extremely difficult to replace, particularly after demonstrating that the EM Drive works in a hard vacuum, and given the better funded efforts in China, that the US should match or exceed.

Those who think that the EM Drive technology is being pursued "under wraps" in the US appear to  be misinformed and disconnected from Aerospace Companies Mgt and federally-funded R&D.

There is a shortfall of funds at NASA, and federally-funded R&D in general under present budget conditions.

There is barely more than one month left until the end of March.

People interested in the EM Drive: this shortfall of funds is real, and EM Drive R&D in the US is in clear and present danger.



« Last Edit: 02/23/2015 12:12 AM by Rodal »

Offline DIYFAN

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....

Treat this thing as a large collection of Casimir Cavities, might work if I can convince Dr. White to do so, and only after we both read through your referenced papers on the topic.  And oh yes, get to Glenn Research Center for a successful replication of what we've seen to date before the end of March, or I may find myself in retirement before I was ready...

..

I put the emphasis on:

 get to Glenn Research Center for a successful replication of what we've seen to date before the end of March, or I may find myself in retirement

That would be a horrible waste of human talent and experience, somebody extremely difficult to replace, particularly after demonstrating that the EM Drive works in a hard vacuum, and given the better funded efforts in China, that the US should match or exceed.

Those who think that the EM Drive technology is being pursued "under wraps" in the US appear to  be misinformed and disconnected from Aerospace Companies Mgt and federally-funded R&D.

There is a shortfall of funds at NASA, and federally-funded R&D in general under present budget conditions.

There is barely more than one month left until the end of March.

People interested in the EM Drive: this shortfall of funds is real, and EM Drive R&D in the US is in clear and present danger.





By the looks of things, there will be another "sputnik" moment--but this time it will be the Chinese not the Russians, and the EM Drive not the satellite.  As much as I'd like to see the US stay out ahead on this one, if the new sputnik-EM Drive-China moment needs to happen to revive the support of the US government and spur a corresponding rise in NASA's budget, then let's hope it happens, and soon.

Online Mulletron

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By the looks of things, there will be another "sputnik" moment--but this time it will be the Chinese not the Russians, and the EM Drive not the satellite.  As much as I'd like to see the US stay out ahead on this one, if the new sputnik-EM Drive-China moment needs to happen to revive the support of the US government and spur a corresponding rise in NASA's budget, then let's hope it happens, and soon.

Well if the reports from China are true, if we don't roll out something impressive soon, they already beat us to the punch.  :(



http://www.economist.com/node/11791539
« Last Edit: 02/23/2015 08:18 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

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