Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1804776 times)

Offline WarpTech

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Where to start? Please read a few things first please, so I don't have to explain it all. Thank you!

https://www.researchgate.net/publication/222942820_Quantum_Ground_States_as_Equilibrium_Particle-Vacuum_Interaction_States
https://www.researchgate.net/publication/24268956_Electromagnetic_Potentials_
Basis_for_Energy_Density_and_Power_Flux
https://www.researchgate.net/publication/223130116_Advanced_Space_Propulsion
_Based_on_Vacuum_%28Spacetime_Metric%29_Engineering

This is an excerpt from a paper I can't post here, regarding the interaction between a charged particle harmonic oscillator and the EM ZPF, that should explain it more clearly than I can...
Todd

Just got around to reading those links Todd.

To get the obvious out of the way, all those papers are from a single person, Harold Puthoff, and none of them have been subjected to peer review.  Seeing as they were all from the same person, I figured I would give him a google and see what sort of background he had.  It's an interesting background, to say the least.  If anyone wants to know what I mean by that, they can check the link:

http://en.wikipedia.org/wiki/Harold_E._Puthoff

After reading that, I thought I would read the wikis on stochastic electrodynamics (SED) and the polarisable vacuum (PV) model of GR to get a quick background.  Links provided:

http://en.wikipedia.org/wiki/Stochastic_electrodynamics
http://en.wikipedia.org/wiki/Polarizable_vacuum

Okay.  It looks like maybe this PV model is a little bit more contentious in the physics community than I was led to believe.  Wikipedia is wikipedia however, so I'm not about to take their word on it.

Now I go to my school's databases.  As best I can tell, a large chunk of everything written on the polarizable vacuum is written by Dr. Puthoff.  There are only a handful of papers on the subject that aren't by him. 

Finally, I read the papers, ordered in the way you linked them:

1)  This is an attempt to reconcile the idea of a radiationless quantum ground state with the fact that accelerating charges ought to produce radiation from a classical viewpoint, correct?  If so, I can reconcile that quite easily: the classical viewpoint is superseded by the quantum viewpoint at such scales, and therefore no reconciliation is actually needed.  Experiments validate the accuracy of quantum theory in explaining away this apparent issue, so in what way does SED add to the discussion? 

2) There isn't really anything to argue about in here.  It's basically him arguing for different variables, but same math, in classical EM.  However, there is absolutely nothing here than goes against anything I said in my original post.  Not sure what his paper was supposed to convey in the context of your reply.

3)  This starts out kind of innocuously, but then unexpectedly takes the whole PV approach.  In order to "get " this paper, you have to already take the PV model as fact.  I guess my question is, on what basis do we accept Dr. Puthoffs PV model?  He introduces it as though it should be obvious to the reader, not even a citation.  It's not obvious to me.  Is there evidence for it? 

I guess what I am saying is, while those citations offer insight into what Puthoff is thinking, they do literally nothing to validate his thoughts.  All I know now is where you got your approach from.  I can't honestly say that this new knowledge has put to bed any of my technical criticisms.             

Thank you for a very detailed post. I don't want to delete any of it. You are correct, these papers do not fix what I wrote in my paper. Over the past few days I've considered what you said, realized what you mean about the potential being undefined and realized the error in my equation. The "logic" I speak of is still there, but the equations are wrong. No argument.

In order to correct it however, it's going to be a lot more involved than a simple weekend paper. So, my thoughts are I should do my homework before releasing a paper. Unfortunately, there's no retracting on the internet, so it's out there, it is what it is. I think the explanation is a good one, even if it lacks the Math to back it up... (for the moment).

Regarding the PV Model, I posted #3 so you could see that since they predict the same metric solutions, between Puthoff, Depp and myself, we have shown that the PV Model is simply an alternative interpretation of GR. One that is more useful for engineering purposes, and easier for laymen to understand. All the evidence of GR also supports PV, there is no difference in their predictions anymore.

Todd
« Last Edit: 06/10/2015 02:13 AM by WarpTech »

Offline rfmwguy

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I have a car like that. As I'm driving along, I throw a biodegradable object out of the window :)

What I was talking about is some gizmo that allows mass to change and then change back to its rest mass value, with no expenditure of energy or momentum. Therefore Mr. Swallow's idea is not to be included, and I suspect, Shells, neither is yours.

Think of it as "a magic brick"
Mine has nothing to do with an EMdrive but it does work and work quite well. So happens it is called A Variable Mass Platform. So your suspicions and assumptions are wrong. Be open to things, you are too bright and dang smart not to be.

Maybe I am misunderstanding you Shell, but are you saying you have/know of something that is able to change its mass with no expenditure of energy?  Like a black box that can gain mass at command, no power needed?  A quick google of variable mass platform didn't satisfy my curiosity.

Actually a brick is a variable mass object. While expending no energy of its own, it can gain mass by being left out in the rain. ;) I think the question is, can object A increase mass with zero energy. If I understand layman physics, there is no such thing as zero energy and I believe, zero mass and zero velocity on any scale you wish to measure...micro or macro.

abt 95% of what we call the universe is dark mass (matter) and energy...we have yet to figure a way to measure/observe it directly. Until we do, I say keep the mind open to all the possibilities.../end rare soapbox post

Offline birchoff

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Where to start? Please read a few things first please, so I don't have to explain it all. Thank you!

https://www.researchgate.net/publication/222942820_Quantum_Ground_States_as_Equilibrium_Particle-Vacuum_Interaction_States
https://www.researchgate.net/publication/24268956_Electromagnetic_Potentials_
Basis_for_Energy_Density_and_Power_Flux
https://www.researchgate.net/publication/223130116_Advanced_Space_Propulsion
_Based_on_Vacuum_%28Spacetime_Metric%29_Engineering

This is an excerpt from a paper I can't post here, regarding the interaction between a charged particle harmonic oscillator and the EM ZPF, that should explain it more clearly than I can...
Todd

Just got around to reading those links Todd.

To get the obvious out of the way, all those papers are from a single person, Harold Puthoff, and none of them have been subjected to peer review.  Seeing as they were all from the same person, I figured I would give him a google and see what sort of background he had.  It's an interesting background, to say the least.  If anyone wants to know what I mean by that, they can check the link:

http://en.wikipedia.org/wiki/Harold_E._Puthoff

After reading that, I thought I would read the wikis on stochastic electrodynamics (SED) and the polarisable vacuum (PV) model of GR to get a quick background.  Links provided:

http://en.wikipedia.org/wiki/Stochastic_electrodynamics
http://en.wikipedia.org/wiki/Polarizable_vacuum

Okay.  It looks like maybe this PV model is a little bit more contentious in the physics community than I was led to believe.  Wikipedia is wikipedia however, so I'm not about to take their word on it.

Now I go to my school's databases.  As best I can tell, a large chunk of everything written on the polarizable vacuum is written by Dr. Puthoff.  There are only a handful of papers on the subject that aren't by him. 

Finally, I read the papers, ordered in the way you linked them:

1)  This is an attempt to reconcile the idea of a radiationless quantum ground state with the fact that accelerating charges ought to produce radiation from a classical viewpoint, correct?  If so, I can reconcile that quite easily: the classical viewpoint is superseded by the quantum viewpoint at such scales, and therefore no reconciliation is actually needed.  Experiments validate the accuracy of quantum theory in explaining away this apparent issue, so in what way does SED add to the discussion? 

2) There isn't really anything to argue about in here.  It's basically him arguing for different variables, but same math, in classical EM.  However, there is absolutely nothing here than goes against anything I said in my original post.  Not sure what his paper was supposed to convey in the context of your reply.

3)  This starts out kind of innocuously, but then unexpectedly takes the whole PV approach.  In order to "get " this paper, you have to already take the PV model as fact.  I guess my question is, on what basis do we accept Dr. Puthoffs PV model?  He introduces it as though it should be obvious to the reader, not even a citation.  It's not obvious to me.  Is there evidence for it? 

I guess what I am saying is, while those citations offer insight into what Puthoff is thinking, they do literally nothing to validate his thoughts.  All I know now is where you got your approach from.  I can't honestly say that this new knowledge has put to bed any of my technical criticisms.             

Thank you for a very detailed post. I don't want to delete any of it. You are correct, these papers do not fix what I wrote in my paper. Over the past few days I've considered what you said, realized what you mean about the potential being undefined and realized the error in my equation. The "logic" I speak of is still there, but the equations are wrong. No argument.

In order to correct it however, it's going to be a lot more involved than a simple weekend paper. So, my thoughts are I should do my homework before releasing a paper. Unfortunately, there's no retracting on the internet, so it's out there, it is what it is. I think the explanation is a good one, even if it lacks the Math to back it up... (for the moment).

Regarding the PV Model, I posted #3 so you could see that since they predict the same metric solutions, between Puthoff, Depp and myself, we have shown that the PV Model is simply an alternative interpretation of GR. One that is more useful for engineering purposes, and easier for laymen to understand. All the evidence of GR also supports PV, there is no difference in their predictions anymore.

Todd

If one accepts the PV Model as an alternative to GR. That should mean any prediction made by the PV Model should also exist in GR. Which means once you have put your math together in the PV Model I would assume your argument would be much stronger if you showed the GR Equivalent for the sake of completeness.

Offline WarpTech

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At this point and since I love to look at problems a little differently. I'll pose a question that take things back to a fundamental level. I need to ask why when laser was shot through a frustum did they see a time differential in the frustum cavity? What in the world could cause this, a warpage of time, which is space? A effect that was many times more than any that could be calculated. It would seem like it was an artifact of something going on within the EMDrive.


Why do you discount the null hypothesis? It is highly likely, >99%, that the experimental conditions were insufficiently robust.
So you believe no statistical significance existed in this set of observations?

Me too.

Offline WarpTech

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...Regarding the PV Model, I posted #3 so you could see that since they predict the same metric solutions, between Puthoff, Depp and myself, we have shown that the PV Model is simply an alternative interpretation of GR. One that is more useful for engineering purposes, and easier for laymen to understand. All the evidence of GR also supports PV, there is no difference in their predictions anymore.

If one accepts the PV Model as an alternative to GR. That should mean any prediction made by the PV Model should also exist in GR. Which means once you have put your math together in the PV Model I would assume your argument would be much stronger if you showed the GR Equivalent for the sake of completeness.

It's already been done for Schwarzschild metric, Reissner-Nordstrom metric, Kerr Metric, Alcubierre Metric. I posed a paper earlier from Matt Visser and crew, that posed GR as a anisotropic crystal model with a variable refractive index. Witten also wrote about it as an analog model of GR.

As an Engineer, the proof is in the pudding. Right or wrong, if it works I'm good with it. The PV Model is far easier to understand than Covariant Tensor mathematics. It facilitates learning something about it without mind boggling Math. I'm told, though I have no reference for it, that most cosmologists use a refractive index model of GR to calculate gravitational lensing effects. So, just look at it as an Engineering Tool, not a theory. It works very well in the scope of where it is applicable.

https://www.researchgate.net/publication/251231445_Event_horizons_in_the_PV_Model

https://www.researchgate.net/publication/265111294_Polarizable_Vacuum_and_the_Schwarzschild_Solution

https://www.researchgate.net/publication/265522894_Polarizable_Vacuum_and_the_Reissner-Nordstrom_Solution

http://vixra.org/pdf/1203.0090v1.pdf

I don't have a reference for the Kerr solution. I worked it out like 10 years ago, but never wrote a paper. I only did it because I needed to work out frame dragging to make the Alcubierre metric work in PV. In the end, I don't even worry about it anymore. I just look at the GR Metric solution and call it a refractive index, where applicable. It's just an alternate interpretation and nobody has shown otherwise.

Todd



Offline SeeShells

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I have a car like that. As I'm driving along, I throw a biodegradable object out of the window :)

What I was talking about is some gizmo that allows mass to change and then change back to its rest mass value, with no expenditure of energy or momentum. Therefore Mr. Swallow's idea is not to be included, and I suspect, Shells, neither is yours.

Think of it as "a magic brick"
Mine has nothing to do with an EMdrive but it does work and work quite well. So happens it is called A Variable Mass Platform. So your suspicions and assumptions are wrong. Be open to things, you are too bright and dang smart not to be.
Well, you didn't tell me what it was yet!
https://www.google.com/patents/US6227515

Pardon me, I think deltaMass was referring to the modulation of the inertial and/or gravitational rest mass of a constant number of point particles by some means. (Like the proposed woodward effect?)   (⌒_⌒;)

You are correct zurael it's not quite the same as filling a hollow table up with water to vary its mass and acoustic dampening characteristics. It was based in solid classical math and physics.

I hope the EMdrive can be explained with a classical physics where nothing is violated but it does seem we have reached an impasse at explaining what's going on. We need more hard data and data that is solid with good lab work. Then hopefully classical can explain it. But what if it doesn't? What if the effect is still there with solid data? There are a few who are thinking beyond the classic physics and while the postulations lack hard data they might in the near future be able to plug good data into their theories to glean what is happening.

It is a good thing to see the debate between WarpTech and DeltaMass with others chipping in, it expands our understanding.

BTW welcome aboard.

Shell


You are correct zurael it's not quite the same as filling a hollow table up with water to vary its mass and acoustic dampening characteristics. It was based in solid classical math and physics.

I hope the EMdrive can be explained with a classical physics where nothing is violated but it does seem we have reached an impasse at explaining what's going on. We need more hard data and data that is solid with good lab work. Then hopefully classical can explain it. But what if it doesn't? What if the effect is still there with solid data? There are a few who are thinking beyond the classic physics and while the postulations lack hard data they might in the near future be able to plug good data into their theories to glean what is happening.

It is a good thing to see the debate between WarpTech and DeltaMass with others chipping in, it expands our understanding.

BTW welcome aboard.

Shell

Thank you for the welcome SeeShells!  (─‿‿─)
I think I could live with momentum being violated in some way, but violation of CoE gives me a panic attack!
I look forward to the revised version of Todd's paper when it is ready.
« Last Edit: 06/10/2015 03:38 AM by zurael »

Offline deltaMass

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What is with you and water, SeeShell?  :)  A variable mass table patent, a hot tub, and your suggestion that the device be floated. I think that, we having thrashed around with the air table anomalies, the water float idea is probably the best of all for seeing thrust directly - and its dynamics. I also recall "curling" a lump of dry ice down a long lab bench as a nipper, and that was extremely low friction.

Offline SeeShells

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What is with you and water, SeeShell?  :)  A variable mass table patent, a hot tub, and your suggestion that the device be floated. I think that, we having thrashed around with the air table anomalies, the water float idea is probably the best of all for seeing thrust directly - and its dynamics. I also recall "curling" a lump of dry ice down a long lab bench as a nipper, and that was extremely low friction.

Thanks!

Love water, it's the neatest molecule ever. Plus, in a hot tub on a clear moonless night I get recharged (might increase my mass too). Looking up I see what this effort is about and I hope our descendants can have even a better view.

I hope that the water idea floats (sorry :) ) and I'd welcome any thoughts on it. The thing i like about it is it will give me data in the XYZ and T axis all at the same time and it's the closest I could get to weightlessness with the EMDrive, plus act as a great heat sink and keep the thermal effects low.
« Last Edit: 06/10/2015 04:23 AM by SeeShells »

Offline WarpTech

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I have a car like that. As I'm driving along, I throw a biodegradable object out of the window :)

What I was talking about is some gizmo that allows mass to change and then change back to its rest mass value, with no expenditure of energy or momentum. Therefore Mr. Swallow's idea is not to be included, and I suspect, Shells, neither is yours.

Think of it as "a magic brick"

One "magic brick"... Delivered! This guy has a battery operating under load since 1999, that has "never" been charged.

http://www.waterconf.org/participants-materials/abstracts/MarcusReid.pdf



No, it's not simply a galvanic cell. The dissimilar metals act as a diode so current will only flow one way, forming a self charging capacitor from clay and water. :)  I actually made one, it works until it dries out, but I didn't seal it the way he seals it to where the water cannot escape. My take is, it converts thermal energy of oscillation between layers of silicate crystal, into a current of electrons similar to a solar panel, but different from a thermocouple in that it apparently doesn't need a temperature difference to operate. If it's hotter, it puts out more energy. He claimed to me that it was the ZPF, I disagree but... who knows. It's new! There are other videos on youtube as well.

How many of you are going to build one with your excess copper and aluminum? If you live in Jersey, just go grab a hand full of gray clay out of the lake. :)

Todd



« Last Edit: 06/10/2015 04:25 AM by WarpTech »

Offline Tetrakis

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No, it's not simply a galvanic cell. The dissimilar metals act as a diode so current will only flow one way, forming a self charging capacitor from clay and water. :)  I actually made one, it works until it dries out, but I didn't seal it the way he seals it to where the water cannot escape. My take is, it converts thermal energy of oscillation between layers of silicate crystal, into a current of electrons similar to a solar panel, but different from a thermocouple in that it apparently doesn't need a temperature difference to operate. If it's hotter, it puts out more energy. He claimed to me that it was the ZPF, I disagree but... who knows. It's new! There are other videos on youtube as well.

Todd

As someone who works with electrochemistry, this is just silly. Two dissimilar metals will always generate a net potential until one dissolves completely, and any kind of silicate can act as an electrolyte in water. This experimental setup is, from a chemical standpoint, only trivially different from zinc and copper stuck into a potato.

Sometimes I think physicists lose control of their pure science hubris and think they know better than the electrochemists. Practically speaking the physics behind electrochemistry has been completely known for about 100 years now.
« Last Edit: 06/10/2015 05:13 AM by Tetrakis »

Offline dustinthewind

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click quote to see video. 
...

Todd

Thanks for sharing this video you linked.  At 7:20 to 9:20 he is talking about two resonating systems but that there should be a phase difference between them and a way of possibly violating energy conservation?  Makes me think about our talks about CoE and also the experiment I proposed about the two resonating cavities that are out of phase with each other ( http://forum.nasaspaceflight.com/index.php?topic=36313.msg1375365#msg1375365 ). 

Not sure if the device he describes is just an electro-chemical battery or not.  I would think if it were it should have a limited capacity and could be analyzed for such.  he seems to indicate shorting it for long periods of time but then again I don't know all there is to know about his set up. 
« Last Edit: 06/10/2015 05:49 AM by dustinthewind »

Online Rodal

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What is with you and water, SeeShell?  :)  A variable mass table patent, a hot tub, and your suggestion that the device be floated. I think that, we having thrashed around with the air table anomalies, the water float idea is probably the best of all for seeing thrust directly - and its dynamics. I also recall "curling" a lump of dry ice down a long lab bench as a nipper, and that was extremely low friction.

Thanks!

Love water, it's the neatest molecule ever. Plus, in a hot tub on a clear moonless night I get recharged (might increase my mass too). Looking up I see what this effort is about and I hope our descendants can have even a better view.

I hope that the water idea floats (sorry :) ) and I'd welcome any thoughts on it. The thing i like about it is it will give me data in the XYZ and T axis all at the same time and it's the closest I could get to weightlessness with the EMDrive, plus act as a great heat sink and keep the thermal effects low.
If the EM Drive is not an experimental artifact, the present experiments show extremely small forces and hence accelerations, and hence inertial forces.  The only test with an EM Drive accelerating in an air bearing (Shawyer's) showed a very slow speed of 2 cm/s (it rotated at an average rotational speed of only 1 revolution every 6 minutes).  So, likely the floater will experience Stokes flow  http://en.wikipedia.org/wiki/Stokes_flow , the type of flow where inertial forces are smaller than viscous forces.



The Reynolds number goes like the mean velocity times the characteristic length divided by the kinematic viscosity. Water's dynamic viscosity is significantly higher than air's, however (due to the density ratio) the kinematic viscosity of water (1.00e-6 m^2/s at room temp.) is about 15.6 times smaller than that of air (1.51e-5 m^2/s at room temp.).

The floater will experience a drag coefficient at low Reynolds number.  Tests show that, the drag coefficient under such conditions is not just related to the geometrical shape of the floater, but that your tank dimensions may play a significant effect (and the distance from the floater to the tank walls if it gets too close):  http://onlinelibrary.wiley.com/doi/10.1002/aic.690070107/abstract

Drag coefficient increases at lower Reynolds number:



tractor beam on water:
http://www.sciencedaily.com/releases/2014/08/140810214202.htm

http://www.nature.com/nphys/journal/v10/n9/full/nphys3041.html



Quote
The team also experimented with different shaped plungers to generate different swirling flow patterns.

As yet no mathematical theory can explain these experiments, Dr Punzmann said.

"It's one of the great unresolved problems, yet anyone in the bathtub can reproduce it. We were very surprised no one had described it before."

« Last Edit: 06/10/2015 01:53 PM by Rodal »

Offline TMEubanks

Re. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory).

This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?

ETA: On reflection that's a dumb question  :-[
Any positive k value will do.

You would have to determine what constitutes an orbit change that is outside the natural decay forces.  Cubesats don't have much power, so they may not get much thrust.  Would a retardation of orbital decay convince anyone?  That is a tricky deal, because orbit decay is sensitive to upper atmosphere expansion/contraction, which is affected by solar activity, etc.

If the thrust was significantly greater than the decay forces, you can use something like the Edelbaum approximation to determine the altitude change you should see with constant, tangential acceleration.  If there is interest, I'll run some quick parametrics to see what that might be.

Here's some analysis of what kind of orbital raising one could expect given constant, tangential, in-plane orbit thrust acceleration starting from a 600 km circular orbit (an average CubeSat altitude). It is not dependent on the type of thruster.

Now if one wanted to apply this to a CubeSat with a little bitty EM Drive, here is how the numbers might stack up:

Typical CubeSat available power: 0.5 W
http://www.diyspaceexploration.com/power-system-budget-analysis/

Typical CubeSat mass: 1.3 kg
http://en.wikipedia.org/wiki/CubeSat

Now, choose your assumed EM Drive efficiency and compute acceleration.  For example if you want to assume 0.1 N/kW, your acceleration would be (0.1 N/kW)*(0.5 W)*(0.001 kW/W)/(1.3 kg)/(9.81 m/s2/g) = around 4 micro-gs.

You can then look at the chart, find the 4 micro-g line and see the altitude gain as a function of thruster on-time.  You can decide for yourself if you want it to have constant thrust at constant power or if you want compute the time you think the universe will let the thruster operate and see how high it will get.

The chart posted above does NOT seem to include atmospheric drag (which dramatically changes orbital lifetimes etc. at low altitudes). Note that most cubesat launches are at 300 - 400 km - the ISS is 330 km, and that is probably the easiest platform to launch from.

A cubesat is 0.1x0.1 meter (1U), so its area is 10^-2 m^2. Its mass will be ~ 1 kg.

Assume 0.1 N/kW or 10^-4 N/W or ~ 5 x 10^-5 N for a 0.5 W drive. That means we want forcing to be
(ideally) << 5 x 10^-3 N/m^2 to be sure a thrust observed is actually from the thruster. (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)

Solar radiation pressure is 4.5 (absorption) to 9 (reflection) micro N / m^2, so radiation force will be
< 10^-7 N, which is fine and can be ignored. (For LEO, the radiation pressure from the Earth is also substantial, and hard to model as it depends on cloud albedo, but it will be < solar and so also can be ignored).

Drag at altitude depends heavily on the solar activity, and thus the solar cycle (which brought Skylab down).  We are near peak right now, which is bad, but in 2 or 3  years or so things could be a lot better. See this prediction:

http://en.wikipedia.org/wiki/Solar_cycle_24#/media/File:Solar_cycle_24_sunspot_number_progression_and_prediction.gif

Looking at the old Harris-Preister model atmosphere (see Figure 2 of
http://stk.com/downloads/support/productSupport/literature/pdfs/whitePapers/A%20Critical%20Assessment%20of%20Satellite%20Drag%20.pdf ) we would want the altitude to be > 300 km. At 400 km, Harris-Preister drag prediction is 3 x 10^-4 N/m^2, which might be OK, but is a little too close for comfort for me.

That says to me that a CASIS launch of a test from Station would not be adequate, but a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials. (For various reasons, get-away specials basically never seem to be available for launches to GEO and higher.)

Also note that a 600 km circular orbit is about as high as you can go with a reasonable expectation of a 25 year post mission lifetime for a cubesat, which is needed to meet IADC guidelines on limiting space debris :
http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/8_Leveque_Orbital_Decay.pdf

Online Rodal

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...

The chart posted above does NOT seem to include atmospheric drag (which dramatically changes orbital lifetimes etc. at low altitudes). Note that most cubesat launches are at 300 - 400 km - the ISS is 330 km, and that is probably the easiest platform to launch from.

A cubesat is 0.1x0.1 meter (1U), so its area is 10^-2 m^2. Its mass will be ~ 1 kg.

Assume 0.1 N/kW or 10^-4 N/W or ~ 5 x 10^-5 N for a 0.5 W drive. That means we want forcing to be
(ideally) << 5 x 10^-3 N/m^2 to be sure a thrust observed is actually from the thruster. (If drag is large, then you will never be able to model it well enough to say that <thrust - drag> is actually meaningful.)

Solar radiation pressure is 4.5 (absorption) to 9 (reflection) micro N / m^2, so radiation force will be
< 10^-7 N, which is fine and can be ignored. (For LEO, the radiation pressure from the Earth is also substantial, and hard to model as it depends on cloud albedo, but it will be < solar and so also can be ignored).

Drag at altitude depends heavily on the solar activity, and thus the solar cycle (which brought Skylab down).  We are near peak right now, which is bad, but in 2 or 3  years or so things could be a lot better. See this prediction:

http://en.wikipedia.org/wiki/Solar_cycle_24#/media/File:Solar_cycle_24_sunspot_number_progression_and_prediction.gif

Looking at the old Harris-Preister model atmosphere (see Figure 2 of
http://stk.com/downloads/support/productSupport/literature/pdfs/whitePapers/A%20Critical%20Assessment%20of%20Satellite%20Drag%20.pdf ) we would want the altitude to be > 300 km. At 400 km, Harris-Preister drag prediction is 3 x 10^-4 N/m^2, which might be OK, but is a little too close for comfort for me.

That says to me that a CASIS launch of a test from Station would not be adequate, but a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials. (For various reasons, get-away specials basically never seem to be available for launches to GEO and higher.)

Also note that a 600 km circular orbit is about as high as you can go with a reasonable expectation of a 25 year post mission lifetime for a cubesat, which is needed to meet IADC guidelines on limiting space debris :
http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/8_Leveque_Orbital_Decay.pdf

Thank you Marshall, this is an excellent explanation as to why nobody has reported launching the EM Drive yet to the International Space Station or such a low Earth orbit.  Launching it to a low orbit where it would be subject to air drag would just serve to continue the present state of uncertain experimental results at ground level, but at a low earth orbit would mean a much higher cost, where the experimental uncertainty of the ground tests with the EM Drives is such that there is no scientific demonstration that an EM Drive force that can be used for space propulsion is being measured, since the experimental variations and uncertainty overwhelm the present results.

It is still fortunate that one can rescue some positive news from this, that launching at >500km circular orbit would be fine and that still qualifies for relatively low rates [but this rules out the International Space Station is definitely out since its orbit is too low 417 km]   :):

Quote
a launch to 500 or 600 km circular orbit would be fine. Launches at that altitude still count as LEO, and are available as get-away specials


That's about the orbit of the Hubble Telescope, isn't it ?  (559 kilometers)



« Last Edit: 06/10/2015 02:12 PM by Rodal »

Offline SeeShells

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If the EM Drive is not an experimental artifact, the present experiments show extremely small forces and hence accelerations, and hence inertial forces.  The only test with an EM Drive accelerating in an air bearing (Shawyer's) showed a very slow speed of 2 cm/s (it rotated at an average rotational speed of only 1 revolution every 6 minutes).  So, likely the floater will experience Stokes flow  http://en.wikipedia.org/wiki/Stokes_flow , the type of flow where inertial forces are smaller than viscous forces.



The Reynolds number goes like the mean velocity times the characteristic length divided by the kinematic viscosity. Water's dynamic viscosity is significantly higher than air's, however (due to the density ratio) the kinematic viscosity of water is about 15.6 times smaller than that of air.
The floater will experience a drag coefficient at low Reynolds number.  Tests show that, the drag coefficient under such conditions is not just related to the geometrical shape of the floater, but that your tank dimensions may play a significant effect (and the distance from the floater to the tank walls if it gets too close):  http://onlinelibrary.wiley.com/doi/10.1002/aic.690070107/abstract

Drag coefficient increases at lower Reynolds number:



tractor beam on water:
http://www.sciencedaily.com/releases/2014/08/140810214202.htm

http://www.nature.com/nphys/journal/v10/n9/full/nphys3041.html



Quote
The team also experimented with different shaped plungers to generate different swirling flow patterns.

As yet no mathematical theory can explain these experiments, Dr Punzmann said.

"It's one of the great unresolved problems, yet anyone in the bathtub can reproduce it. We were very surprised no one had described it before."


Water rocks (only if frozen)

Thanks for the great info Dr Rodal it will help.

My first quickie drawing that lead me to the idea of a water test.

This is the way I think the test will bear results without the issues of trying to navigate in a horizontal position across the water. It can measure thrust by its vertical Z displacement up or down and any rotational components T along with X and Y at the same time, although I don't think T and X and Y should be a large factor but if it is then we need to rethink what is happening with the EMdrive.

Of course the unit will be water tight.
 

Offline OttO

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It can measure thrust by its vertical Z displacement up or down

Do you plan to put in it toaster resistors to measure the infrared influence  :)

Offline SeeShells

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It can measure thrust by its vertical Z displacement up or down

Do you plan to put in it toaster resistors to measure the infrared influence  :)

No, no toaster elements allowed.

I will be using a plastic container to keep any magnetic components from the EMdrive acting on the side walls. And don't laugh as this will work fine and it is inexpensive.

Online Rodal

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Water rocks (only if frozen)

Thanks for the great info Dr Rodal it will help.

My first quickie drawing that lead me to the idea of a water test.

This is the way I think the test will bear results without the issues of trying to navigate in a horizontal position across the water. It can measure thrust by its vertical Z displacement up or down and any rotational components T along with X and Y at the same time, although I don't think T and X and Y should be a large factor but if it is then we need to rethink what is happening with the EMdrive.

Of course the unit will be water tight.
 
Since you may want to test it small end pointing up and small end pointing down, one suggestion is to encase the truncated cone inside a cylinder with inner diameter the same outer diameter as the big base of the truncated cone so that the hydrodynamic profile is identical in both orientations (small end pointing down and small end pointing up) and hence there is the same drag coefficient in both orientations. 

Only the encasing cylinder's outer surface will be in contact with the water, rather than the EM Drive truncated cone's  walls which will be inside the cylinder.

This will also take care of the fact that the displaced volume of water is a nonlinear function of truncated cone depth (because its cross-sectional area changes with depth).  The cylinder's displaced volume of water will just be a linear function of its depth.
« Last Edit: 06/10/2015 02:31 PM by Rodal »

Offline SeeShells

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Water rocks (only if frozen)

Thanks for the great info Dr Rodal it will help.

My first quickie drawing that lead me to the idea of a water test.

This is the way I think the test will bear results without the issues of trying to navigate in a horizontal position across the water. It can measure thrust by its vertical Z displacement up or down and any rotational components T along with X and Y at the same time, although I don't think T and X and Y should be a large factor but if it is then we need to rethink what is happening with the EMdrive.

Of course the unit will be water tight.
 
Since you may want to test it small end pointing up and small end pointing down, one suggestion is to encase the truncated cone inside a cylinder with inner diameter the same outer diameter as the big base of the truncated cone so that the hydrodynamic profile is identical in both orientations and hence there is the same drag coefficient in both orientations.  The cylinder will be in contact with the water, rather than the EM Drive truncated cone's  walls.
I understand (had to read twice) and it's a even better idea, as I don't have to worry as much in waterproofing the EMdrive as well. The endplates will cause more resistance to movement considering the viscosity of the water than the drag components of the water on the side walls. Thanks for the great idea!
Shell

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