Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2164632 times)

Offline rthrfrd

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Hi all, lurker here,

Sadly I have no theoretical contribution to make, however as more people attempt to implement the device I hope I can help with the collaboration:

I've created a rough model of the device (with no idea of actual ratios/dimensions - if anyone has some I can quickly update) in a fairly new tool called Onshape (you can sign up for free):

https://cad.onshape.com/documents/17ece60a89f74af4b788d7c3/w/2f14c5d1fcd84a14ab67b3c2

Bit of background: It's an online, collaborative parametric modelling tool (think SolidWorks). The feature set naturally isn't comparable yet, but for the purposes of prototyping it's pretty intuitive, and free ;D The best thing about being web-based is anyone can fork (make their own version of) my document... and others can make versions of theirs... and so on, so my hope is it's a way that people (particularly those without access to this kind of tool) could refine engineering prototypes together.

For those of you not familiar: the 3D model is built from a series of 2D sketches and extrusions. If you constrain your dimensions correctly (as I've tried to do!) then you can quickly make changes to the dimensions to test different permutations of the design. If you've never used this kind of software before (I'm no expert), there are some nice video guides which can help you quickly get stuck in.

When you look to actually fabricate a prototype you can export to various common formats: https://cad.onshape.com/help/index.htm#cshid=export

I've just done a quick draft of the device itself - you could equally extend to model the whole experimental setup.

Disclaimer: I am in no way associated with Onshape! Just thought it was interesting compared to what's out there :)

Offline TheTraveller


Both Shawyer & the Chinese claim their many physical devices produce thrust and the measurement of that thrust is in agreement with their theoretical calculations. Both also claim no new physics is needed and CofE / CofM are conserved.

I mean you say it can't work as they claim, yet it does and the measured thrust from many devices, measured in different ways, in different labs, in different countries all closely matched what their theory says the thrust should be.

With respect, just maybe your explanation / understanding of what is happening inside the frustum is not at the same level as Shawyer or the Chinese?

Or perhaps they are all making basic mistakes in their sloppy experimental setups, pumping kW of microwave power into poorly shielded cavities and reporting thrusts near their error limits?

This is all standard physics, supported by a century of experiments all conducted with far more precision and rigor than anything published on the EM drive.

Incidentally, after doing a brief literature search, I have attached an experiment performed in the early 90's on a superconducting frustrum cavity, with a Q of at least 20,000. The paper is nice in that it gives explicit formulae for the EM fields in such a cavity. Their classical model fits the data perfectly. I might also note that they didn't see the thing shoot out of their dewar...

Guess you have not read the Chinese data:

http://www.emdrive.com/NWPU2010translation.pdf
http://www.emdrive.com/NWPU2010testresults.pdf
http://www.emdrive.com/yang-juan-paper-2012.pdf

The thrust measured was not the EagleWorks mosquito landing on your arm level. Maybe read the papers before claiming

Quote
Or perhaps they are all making basic mistakes in their sloppy experimental setups, pumping kW of microwave power into poorly shielded cavities and reporting thrusts near their error limits?

as a quick way to dismiss their results.

A.single paper is not a magic wand which causes all previous results to disappear. It cannot chan ge the tens of thousands of previous measure ments that have taken place in the last 50years. How do you refute cavities in pillbox shape that are used in GPS satellite atomic clocks? These have been characterized down to sub nanowatt levels, and no mystery power draw is observed and no thrust is observed in the GPS satellites (the location of which must be known very well.)

I don't refute the past nor existing devices as you should not. However that does not say they are all that is possible or that we know all possible variations of the theories thus embodied.

There is not a single paper, there are many.

Before signing a license deal with SPR, involving both the US and UK governments, Boeing would have crawled all over the SPR, all their devices, test rigs and especially the Demonstrator Engine and its static and dynamic test rigs. As part of that license deal, SPR built, tested and shipped the Flight Thruster to Boeing. SPR's claims for the results of the Flight Thruster are well known to Boeing. Never heard Boeing claim the Flight Thruster did not meet contract conditions.

BTW on the EagleWorks slide showing the various SPR devices, the Flight Thruster is labelled as a "High Fidelity Test Article". As the slide is from NASA. I'm sure SPR did not write that on the slide.

Just maybe something is happening that is inside the existing theories, yet largely unrealised. Both the Chinese and SPR state no new physics is needed and both CofE and CofM are conserved. Their theory math supports their claims and as well the theory math predicts the thrust they measured in 3 different ways.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

How about extrapolating/interpolating downward by calculating dimensions from resonant frequencies of these test articles? Use that interpolation to select a smaller sized set of cavity dimensions and scale up the frequencies to get that thrust signal out of the "iffy" zone?
The point I was making was that we don't know whether or not higher frequencies produce higher thrust. That's unless you happen to know.

Shawyer states:

F = (2 * Df * Po * Q) / c (Po = applied power in watts)

Many factors at play. Df hits max when the small end operates at just above cutoff and then drops as frequency climbs. The applied Rf frequency needs to achieve resonance at some 1/2 wave of the cavity electrical length between the end plates. So to a large degree, the length of the frustum sets a number of 1/2 multiple input Rf frequencies.

Haven't seen anything that implies you will get more thrust with higher frequencies.

The attachment from Dr. Rodal is a good resource.
« Last Edit: 05/19/2015 09:02 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

How about extrapolating/interpolating downward by calculating dimensions from resonant frequencies of these test articles? Use that interpolation to select a smaller sized set of cavity dimensions and scale up the frequencies to get that thrust signal out of the "iffy" zone?

The only testers that had "Iffy" zone signals were EagleWorks and their devices fitted with dielectrics.

Shawyer did use dielectrics at one time, and has patents covering their use, but gave them up and advised others here to do likewise.

Shawyer's 1st device achieved 16mN at 850W, the Demonstrator Engine rotary test unit achieved 96mN at 334W and the Flight Thruster achieved 175mN at 430W. Well out of any "Iffy" zone. At 175 mN or 17.9 gf you could feel that with your hand if the power were turned off and on.
« Last Edit: 05/19/2015 09:01 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

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It should be pointed out that this Shawyer thrust equation
1) F = 2 Df Po Q / c
has been rejected by the physics community. Their version is
2) F = 0.

Let's however go with it. Assuming that we do a decent job with Df and so get Df = DfMax = 1. Then the equation predicts that you get 2*Q times the thrust you'd get from a photon rocket of the same power.
But since a cavity's Q = w E / P, where w=angular frequency, E=stored energy, P=input power, Shawyer's thrust equation becomes
3) F = (2 E/c) w
and thus thrust scales linearly with frequency, and linearly with the stored energy.

Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
That's light enough and small enough to fit on a Mettler H20 balance, an inspired piece of Swiss mechanical engineering that reliably gets you 10 microgram-weight resolution, or 0.1 microNewtons.
Equation 1) with Df=1 predicts a thrust of Q/1000 microNewtons.
Thus the Mettler should detect thrust for Q > 100.
This is usually far exceeded by optical cavities, which can have Qs up in the millions.

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.


« Last Edit: 05/19/2015 09:37 PM by deltaMass »

Offline SeeShells

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A thought experiment:

Many physicists postulate that we live in a 3+1 deSitter space, and specifically I refer to Lisa Randall, Raman Sundrum http://arxiv.org/abs/hep-ph/9905221

I have Warped Passages by Lisa Randall, I need to get it out and re-read it, she is one of my heroes and if I believe (need to look again) she finds quasicrystals might have an underlying structure into other dimensions. Whoa! Ok need to sit in my hot tub and think some.

I have all of her books (4 I think, or is it 3?).  In Warped Passages I swear I remember her mentioning the possibility of inflating the 4sd (4th spatial dimension) - though there was no known mechanism.  Just like there is no known physical mechanism for the  inflationary period of the Universe.
Knocking on Heaven's Door and another about the Higgs.  Think it's 3.
It is somewhat light but meant for a specific audience, but she likes the string theory (I always liked it) and if you can write and make sense from our perspective another dimension without higher order math, my hat is off.
I keep on associating (several papers and books) again and again to magneto-chiral matter and how it interacts to the Casimir force and  momentum, there seems a wonderful link there. "I'M GIVIN' HER ALL SHE'S GOT, CAPTAIN!" Need more brains!

Offline TheTraveller

It should be pointed out that this Shawyer thrust equation
1) F = 2 Df Po Q / c
has been rejected by the physics community. Their version is
2) F = 0.

Let's however go with it. Assuming that we do a decent job with Df and so get Df = DfMax = 1. Then the equation predicts that you get 2*Q times the thrust you'd get from a photon rocket of the same power.
But since a cavity's Q = w E / P, where w=angular frequency, E=stored energy, P=input power, Shawyer's thrust equation becomes
3) F = (2 E/c) w
and thus thrust scales linearly with frequency, and linearly with the stored energy.

Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
That's light enough and small enough to fit on a Mettler H20 balance, an inspired piece of Swiss mechanical engineering that reliably gets you 10 microgram-weight resolution, or 0.1 microNewtons.
Equation 1) with Df=1 predicts a thrust of Q/1000 microNewtons.
Thus the Mettler should detect thrust for Q > 100.
This is usually far exceeded by optical cavities, which can have Qs up in the millions.

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.

Of course frequency has an effect on thrust. Dumb statement for me to make as I only considered Df in a fixed frustum. Was thinking about my Flight Thruster design simulator, which did have a fixed Q of 50,000 at 3.85GHz but not anymore.

Thanks for that input. "Click" another piece of the puzzle drops into place.
« Last Edit: 05/19/2015 09:51 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline pogsquog

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Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
...

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.

I suspect it is quite difficult to build something with the required properties in laser wavelengths.

Offline WarpTech

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A thought experiment:

Many physicists postulate that we live in a 3+1 deSitter space, and specifically I refer to Lisa Randall, Raman Sundrum http://arxiv.org/abs/hep-ph/9905221.  Briefly they claim an additional finite dimension between our brane (weak/Tev) and a gravity brane (strong) where gravity actually exists.  The distance between these branes is the reason that gravity is such a comparatively weak force.  The length of this 4th spacial dimension has an upper limit of somewhat less than 1 millimeter (otherwise we would have seen its effects long ago). The force of gravity on the gravity brane is expected to be 16 orders of magnitude greater than it is on our brane....

For whatever it's worth, a short note that Dr. White and Paul March both have invoked a (4+1) brane of spacetime in their explanation and papers.

Yes, I noticed that. Though I didn't follow why they did so, it seemed disconnected to me. I thought they referred to a 3+1 space, but if they used 4+1 then they included time. I'm more inclined to use 3+1 and set time aside.

Gravity doesn't work the way they imagine and there is no evidence that higher dimensions actually exist, or that they have any influence on our 3 + 1 dimensions. However, gravity does present itself as a slight change in "scale" at the sub-atomic scale. Scale can be formulated as a 5th dimension that is dependent on the other 4, as in Kaluza-Klien theory, which has nothing to do with branes BTW. IMO, the whole of physics has been falling down a rabbit hole to nowhere, ever since String theory was created.

Todd

Offline txdrive

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Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
...

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.

I suspect it is quite difficult to build something with the required properties in laser wavelengths.
Make a laser diode of appropriate shape with no exit. edit: fibre lasers could be of interest as well. You can make tapered fibre.
« Last Edit: 05/19/2015 09:59 PM by txdrive »

Offline pogsquog

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Shawyer states that the cavity reflectors must be half a wavelength apart, which might be a bit fiddly at laser frequencies.

Offline Rodal

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...

Of course frequency has an effect on thrust. Dumb statement for me to make as I only considered Df in a fixed frustum. Was thinking about my Flight Thruster design simulator, which did have a fixed Q of 50,000 at 3.85GHz but not anymore.

Thanks for that input. "Click" another piece of the puzzle drops into place.

It should be pointed out that this Shawyer thrust equation
1) F = 2 Df Po Q / c
has been rejected by the physics community. Their version is
2) F = 0.

Let's however go with it. Assuming that we do a decent job with Df and so get Df = DfMax = 1. Then the equation predicts that you get 2*Q times the thrust you'd get from a photon rocket of the same power.
But since a cavity's Q = w E / P, where w=angular frequency, E=stored energy, P=input power, Shawyer's thrust equation becomes
3) F = (2 E/c) w
and thus thrust scales linearly with frequency, and linearly with the stored energy.

Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
That's light enough and small enough to fit on a Mettler H20 balance, an inspired piece of Swiss mechanical engineering that reliably gets you 10 microgram-weight resolution, or 0.1 microNewtons.
Equation 1) with Df=1 predicts a thrust of Q/1000 microNewtons.
Thus the Mettler should detect thrust for Q > 100.
This is usually far exceeded by optical cavities, which can have Qs up in the millions.

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.
To make F frequency (w) dependent you had to perform a variable substitution.
E is dependent on Q, so nothing is gained by that variable substitution.
You (and us) have a sense for what Q is, while we don't have a sense of what is E (without knowing Q).


There  is no advantage to use w*E instead of using Q*Po , as you yourself implicitly admitted when the time came  for you to estimate F (you calculated it in terms of Q*Po, instead of w*E)

You used:

F = 2 Po Q / c  for different Q values (Q=100 and Q=5*10^8)

which is not explicitly dependent on frequency (given Q),  all you had to use was Po, and Q: you never had to use the frequency.


« Last Edit: 05/19/2015 10:18 PM by Rodal »

Offline deltaMass

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Indeed you are correct, because eqn 3 suppresses the possible frequency dependence of E.

So let's go with thrust not being frequency dependent. That means that far higher thrust-to-weight ratios can be expected at higher frequencies.

And in that vein, I like the idea of a fully self-contained tapered fibre laser.
It would weigh next to nothing - the battery would be most of the weight.
« Last Edit: 05/19/2015 10:23 PM by deltaMass »

Offline TheTraveller

Shawyer states that the cavity reflectors must be half a wavelength apart, which might be a bit fiddly at laser frequencies.

Even tricker still as the internal guide wavelengths vary from end to end and are not at the applied Rf wavelength.

Have asked Shawyer how to calc frustum resonance wavelength as per applied Rf wavelength.
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Offline Rodal

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Indeed you are correct, because eqn 3 suppresses the possible frequency dependence of E.

So let's go with thrust not being frequency dependent. That means that far higher thrust-to-weight ratios can be expected at higher frequencies.

And in that vein, I like the idea of a fully self-contained tapered fibre laser.
In any vibration problem one can express Q as 2*Pi*f*EnergyStored/PowerLoss (it can be a mechanical vibration).
The usual and practical way to asses the damping of vibration is to use Q (or the damping ratio = 1/(2Q), instead of using the Energy Stored.  That's why when it came time for you to come up with numbers you had to use Q*Po, instead of w*E
« Last Edit: 05/19/2015 10:49 PM by Rodal »

Offline TheTraveller

Indeed you are correct, because eqn 3 suppresses the possible frequency dependence of E.

So let's go with thrust not being frequency dependent. That means that far higher thrust-to-weight ratios can be expected at higher frequencies.

And in that vein, I like the idea of a fully self-contained tapered fibre laser.
It would weigh next to nothing - the battery would be most of the weight.

Well it is frequency dependent as a set frustum Df is frequency dependent.
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Offline Rodal

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Q is a primary dimensionless parameter that compares the exponential time constant τ for decay of an oscillating physical system's amplitude to its oscillation period. E (the energy stored) is not dimensionless, and it is not a primary parameter.

Offline deltaMass

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Of course in practice we have a P(w) dependence based on the fatness of your wallet. Doing it at 2 GHz means you can cheaply get kilowatts. Doing it at 22 GHz with a Gunn diode will get you only a few milliwatts.  And again, doing it at light frequencies also means milliwatts unless you want to spend mucho bucks.

All this is somewhat offset by higher Qs at higher frequencies.

But at the risk of labouring the point, much superior thrust-to-weight ratios can be had with lasers, where the weight is the all-up weight of everything including the batteries.
« Last Edit: 05/19/2015 10:45 PM by deltaMass »

Offline WarpTech

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It should be pointed out that this Shawyer thrust equation
1) F = 2 Df Po Q / c
has been rejected by the physics community. Their version is
2) F = 0.

Let's however go with it. Assuming that we do a decent job with Df and so get Df = DfMax = 1. Then the equation predicts that you get 2*Q times the thrust you'd get from a photon rocket of the same power.
But since a cavity's Q = w E / P, where w=angular frequency, E=stored energy, P=input power, Shawyer's thrust equation becomes
3) F = (2 E/c) w
and thus thrust scales linearly with frequency, and linearly with the stored energy.

Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
That's light enough and small enough to fit on a Mettler H20 balance, an inspired piece of Swiss mechanical engineering that reliably gets you 10 microgram-weight resolution, or 0.1 microNewtons.
Equation 1) with Df=1 predicts a thrust of Q/1000 microNewtons.
Thus the Mettler should detect thrust for Q > 100.
This is usually far exceeded by optical cavities, which can have Qs up in the millions.

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.

More accurately, F = (2 Df Po Q / c) * D, where D is the Duty Cycle of the output. IF it were to put out thrust continuously at this value of F, CoE would be violated, because you are only putting in Po*t, not Q*Po*t. It takes time to store energy, and once it is stored, it can only deliver thrust for a limited amount of time before it needs to be recharged again. So there is a duty cycle associated with this thing that is being ignored.

Personally, I do not find Shawyer's equation to be that far off. I agree, his theory is flawed if you consider only perfectly conducting walls and group velocity. But, given asymmetrical losses, his assumption that F2 - F1 > 0 is exactly what it is. Two forces that are not exactly equal, opposing each other. The "how and why" are debatable, but the reality of it is not. Had someone done a Buckingham Pie Theory analysis of this, just based on input variables, the Max. potential thrust, 2*Q*P/c multiplied by an unknown Df based on the geometry, and whose value is to be experimentally determined, is exactly what you should get.

Todd D.

 
« Last Edit: 05/19/2015 10:58 PM by WarpTech »

Offline TheTraveller

It should be pointed out that this Shawyer thrust equation
1) F = 2 Df Po Q / c
has been rejected by the physics community. Their version is
2) F = 0.

Let's however go with it. Assuming that we do a decent job with Df and so get Df = DfMax = 1. Then the equation predicts that you get 2*Q times the thrust you'd get from a photon rocket of the same power.
But since a cavity's Q = w E / P, where w=angular frequency, E=stored energy, P=input power, Shawyer's thrust equation becomes
3) F = (2 E/c) w
and thus thrust scales linearly with frequency, and linearly with the stored energy.

Let's imagine we have a little 150 mW laser diode attached to a resonant cavity, powered by a tiny battery.
The whole thing weighs probably about 50 gm (SWAG).
That's light enough and small enough to fit on a Mettler H20 balance, an inspired piece of Swiss mechanical engineering that reliably gets you 10 microgram-weight resolution, or 0.1 microNewtons.
Equation 1) with Df=1 predicts a thrust of Q/1000 microNewtons.
Thus the Mettler should detect thrust for Q > 100.
This is usually far exceeded by optical cavities, which can have Qs up in the millions.

So this experiment is expected to easily detect thrust from this little device.
Indeed, if Q > 5*108, it would lift off the bench when appropriately oriented.
If Shawyer is correct, that is.

More accurately, F = (2 Df Po Q / c) * D, where D is the Duty Cycle of the output. IF it were to put out thrust continuously at this value of F, CoE would be violated, because you are only putting in Po*t, not Q*Po*t. It takes time to store energy, and once it is stored, it can only deliver thrust for a limited amount of time before it needs to be recharged again. So there is a duty cycle associated with this thing that is being ignored.

Personally, I do not find Shawyer's equation to be that far off. I agree, his theory is flawed if you consider only perfectly conducting walls and group velocity. But, given asymmetrical losses, his assumption that F2 - F1 > 0 is exactly what it is. Two forces that are not exactly equal, opposing each other. The "how and why" are debatable, but the reality of it is not. Had someone done a Buckingham Pie Theory analysis of this, just based on input variables, the Max. potential thrust, 2*Q*P/c multiplied by an unknown Df based on the geometry, and whose value is to be experimentally determined, is exactly what you should get.

Todd D.

It has not been ignored.

Sgawyer has discussed the TC and time to recharge the cavity energy lost to kinetic.

His superconducting space plane uses 8 EM Drives, arranged like 2 side by side 4 cylinder inline motors, driven in short pulses of less than 1 TC and phased apart to deliver continuous thrust.
« Last Edit: 05/19/2015 11:08 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

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