Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2099970 times)

Online Rodal

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So should everyone be using perforated copper sheeting??  Admittedly, I can't even begin to imagine how this would affect the performance of the drive.  Do the various theories need a solid wall or as long as the perforations are sufficiently fine it should not matter??   :P

https://concordsheetmetal.com/store/perforated-copper/

Good thoughts as the mesh would be a cost-effective solution for trials, however, its likely going to be a lower Q which theoretically inhibit power/effeciency. My old company used this exact material in an impedance matching network, while a competitor used solid aluminum. At the end of the day, the 50 ohm freq matching was extended abt 25% by using the more expensive solid cone. I'd suggest initial proof of performance testing on the mesh, moving up to silver-plated flash over copper.

Another topic I have not see discussed is intermodulation products caused by dissimilar metals, perhaps nickel( Magnetic)-plating of connectors and such. I'm not sure if IM products would adversly affect the trials, as the magnetron is inherently spraying out bits all over the spectrum.

OK all good points.  But it is not at all clear that one wants a high Q.

The highest thrust was achieved by Prof. Yang with an effective Q of only ~1500 (take into account that the reported Q's appear much larger because of the unorthodox way the Chinese report Q, if one uses the same method as in the West, Yang's Q was relatively low).

Todd's theory shows that one doesn't want a huge Q.

So using a mesh would be of research interest, to see what difference it makes., whether it makes no difference, or is worse or better

Offline deltaMass

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When Iulian flips it and if he finds the same -0.5 gm ballpark, I am confident that he will report it. Unlike some people, he seems to have no trouble in reporting null results. The mark of the true scientist.

Offline pogsquog

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Back of the envelope calculation for the 'hot air balloon' explanation, considering the pessimistic possibility that we just have a really heavy, electric powered Chinese sky lantern:

If we assume (worst case!!)
-a perfectly ventilated cavity
-that the air is heated primarily by the microwave, with a negligible impact from conduction/convection from the frustum to the air

then using convective airflow calculator:

temperature difference between inside and outside of cavity = 54 K
temperature of ambient = 273 + 20 K
cone surface area = 0.163 m^2
cone volume = 0.0063 m^3
mass of air displaced by heating air in cavity to +54 K ~= 1 gram
air flow rate (volume) = 0.0097 m^3 / s

i.e. it would take ~0.6 seconds for the hot air to leave the chamber. There will be a residual effect due to the heat of the cavity itself, with a much longer time period (cooling time of the metal, probably tens of seconds).

So, I guess this shows that it is not impossible to see a rapid time constant for thermal lift, if your frustum behaves quite like a sky lantern.

On the other hand, if we assume that the thrust is coming from a single hole, and is caused purely by thermal expansion of the air in the frustum, then we would expect to see a force like:

assume rate of change of air temperature is ~ 10 K per second, at first. Then thermal expansion will push ~ 3% of the air out of the cavity per second. If this is pushed through a hole of 5 mm, then the resulting force will be equivalent to something like 0.6 grams (falling over time as the system moves towards equilibrium), which is also in the ballpark of the measured force.

Offline WarpTech

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...

Spacecraft move in the opposite direction to the thrust of the engine. EM Drive is no different.

Propellant comes out of a rocket engine.  According to Shawyer nothing comes out of an EM Drive.

If nothing is coming out of the EM Drive, how can it have a thrust force in the opposite direction to its acceleration?

Has someone measured that thust force you are referring to ? If this thrust force of the EM Drive has been measured, how was the thrust force measured simultaneously with a measurement of the acceleration in the opposite direction  ?
 ???

As you well know it was measured and reported here:
No, I don't know that.

I see a chart that Shawyer put together.  Nobody here could explain why the Demo Engine has it in both directions.

I never saw a paper detailing how such a thrust was measured simultaneously with measuring the acceleration in the opposite direction.

Shawyer is in business to sell licenses, not to give it all away so any DIY guy can replicate and go into business against SPR and it's clients.

There are holes in what he has put in the public domain. I doubt he has any intention of filling them in. For guys like me, working to replicate the EM Drive, we need to learn to follow the bread crumb trail he has left. For me, that trail is strong and delivering good intel.

I'm highly confident of replicating his Flight Thruster and getting close to his results.

Shawyer has patents on the  EM Drive.  One of the fundamental agreements and understanding under which patents are conferred by a state (or the European Union) to an inventor is that the inventor must disclose all the  "information material to patentability." See: Duty to disclose information material to patentability.

In intellectual property one always has to make a choice: trade secret (like the Coca Cola formula) or patent.

Under trade secret you run the risk that the secret may become public (by independent discovery), but as long as it is a trade secret it has no expiration.

A patent gives you a state-conferred monopoly, but it has an expiration date.  The state gets to make the patent information public in exchange for conferring the patent's monopoly to the inventor.

I'm sure that Shawyer would disagree with your statement if you are referring to information material to patentability protected by Shawyer's patents. 

On the other hand, if you are not referring to information material to patentability, then the information you are referring to "so any DIY guy can replicate and go into business" is not protected by Shawyer's patents.

Has anyone tried to pull a copy of the patent from the patent office?


Online Rodal

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[...
Has anyone tried to pull a copy of the patent from the patent office?
These are all the patent documents I know of, that have been posted in this thread.  All of them are UK patent applications.

EDIT: see http://forum.nasaspaceflight.com/index.php?topic=36313.msg1376186#msg1376186 for status of Shawyer's IP

Under justia, this is all that shows up (not an EM Drive patent):

http://patents.justia.com/inventor/roger-j-shawyer

Same under Google patents

and I couldn't find his EM Drive patents under USPTO search under inventor either
« Last Edit: 05/19/2015 12:24 AM by Rodal »

Offline SeeShells

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Spacecraft move in the opposite direction to the thrust of the engine. EM Drive is no different.

Propellant comes out of a rocket engine.  According to Shawyer nothing comes out of an EM Drive.

If nothing is coming out of the EM Drive, how can it have a thrust force in the opposite direction to its acceleration?

Has someone measured that thust force you are referring to ? If this thrust force of the EM Drive has been measured, how was the thrust force measured simultaneously with a measurement of the acceleration in the opposite direction  ?
 ???

As you well know it was measured and reported here:
No, I don't know that.

I see a chart that Shawyer put together.  Nobody here could explain why the Demo Engine has it in both directions.

I never saw a paper detailing how such a thrust was measured simultaneously with measuring the acceleration in the opposite direction.
I saw the chart and thought the same thing, it is a conundrum leaving me to just scratch my head perplexed.

Offline pogsquog

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Back of the envelope calculation for the 'hot air balloon' explanation, considering the pessimistic possibility that we just have a really heavy, electric powered Chinese sky lantern:

...

Thanks for running the numbers  :)

What is the basis for the air flow rate (volume) = 0.0097 m^3 / s ?  is it an assumption or is it an outcome of equations? if an outcome of equations, what where the equations  or theory used in the calculator?

I just plugged the numbers into a convection calculator:

http://www.engineeringtoolbox.com/convective-air-flow-d_1006.html

Clearly, this is an approximation, but I think it is sufficient for the purpose of showing that one cannot completely rule out a thermal (hot air balloon) effect for this particular result, as a rapid replacement of the air in the chamber is theoretically possible (assuming it is well ventilated), so it is possible to see a rapid loss of up-thrust after power-off.

Finding similar thrust in other orientations would rule this out, although the possibility of temporary thrust due to thermal expansion causing directed air flow, and sustained air flow due to jet effects would still exist; directed air flows of just a few percent of the frustum's volume per second are sufficient to cause this effect, which is easily possible when you are pumping a kilowatt of power into a small space.

Online AnalogMan

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[...
Has anyone tried to pull a copy of the patent from the patent office?
These are all the patent documents I know of, that have been posted in this thread.  All of them are UK patent applications.

I don't know whether any patents were actually conferred for the EM Drive.

Under justia, this is all that shows up (not an EM Drive patent):

http://patents.justia.com/inventor/roger-j-shawyer

Same under Google patents

and I couldn't find his EM Drive patents under USPTO search under inventor either

Did you find any?

I edited my post to read:  patent (applications ?).  Thanks for questioning, as I didn't recall that all (apparently ?)  that has been posted here are just applications in the UK.

For the publication numbers listed in the above post:

GB2493361 High q microwave radiation thruster
Filed 6Feb11 - Awaiting first examination

GB2399601 High thrust microwave engine
Filed 13Mar03 - Granted 31Jan06 - last renewed 6Mar15

GB2334761 Microwave thruster for spacecraft
Filed 29Ap88 - Granted 21Mar00 - last renewed 1Apr15

GB2229865 Electrical propulsion unit for spacecraft
Filed 1Nov88 - Granted 5May93 - now ceased (not in force from 1Nov97)

https://www.gov.uk/search-for-patent
« Last Edit: 05/19/2015 12:09 AM by AnalogMan »

Offline tchernik

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Back of the envelope calculation for the 'hot air balloon' explanation, considering the pessimistic possibility that we just have a really heavy, electric powered Chinese sky lantern:

...

Thanks for running the numbers  :)

What is the basis for the air flow rate (volume) = 0.0097 m^3 / s ?  is it an assumption or is it an outcome of equations? if an outcome of equations, what where the equations  or theory used in the calculator?

I just plugged the numbers into a convection calculator:

http://www.engineeringtoolbox.com/convective-air-flow-d_1006.html

Clearly, this is an approximation, but I think it is sufficient for the purpose of showing that one cannot completely rule out a thermal (hot air balloon) effect for this particular result, as a rapid replacement of the air in the chamber is theoretically possible (assuming it is well ventilated), so it is possible to see a rapid loss of up-thrust after power-off.

Finding similar thrust in other orientations would rule this out, although the possibility of temporary thrust due to thermal expansion causing directed air flow, and sustained air flow due to jet effects would still exist; directed air flows of just a few percent of the frustum's volume per second are sufficient to cause this effect, which is easily possible when you are pumping a kilowatt of power into a small space.

I fully support and thank people looking for alternative, more mundane explanations for this. Because all these objections will appear again and again, so better address them now.

The way out of this, as I see it, is for someone with an Emdrive (in this case, Iulian) to:

- Run the thrust tests with the device in all directions, and in this case upside-down, to see if the acceleration vector continues going to the same direction as before (from the big end towards the small end). This would rule out hot air buoyancy as an explanation for the thrust.

- Visibly inspect and/or check with a smoke test if there are holes or obvious exhaust plumes coming out from the device's big end, to rule out any unintended thermal "rocket" effect.

Or, alternatively, build and test a copper wire-mesh Emdrive, which would immediately keep all the frustum internal air at the same pressure as the outside (so no thermal expansion effects).

But I'm afraid we would be over-taxing the good will of Iulian with that last experiment. But such experiment would be very valuable indeed, without a doubt.

Offline Carl G

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Please remember this is a long thread and this site's forum has a high signal to noise factor.

If you like a post, "like" it. Please only post if you have something useful to add to the thread, otherwise it will be deleted.

The reason is 99 percent of people (nearly a million reads) are watching this thread and those catching up don't need to have to search through posts that don't add anything. Thanks.

Offline TheTraveller

From the pdf's
Shawyer uses/used an internal "dielectric"

Shawyer drops a few hints:

1) The Flight Thruster and the Chinese units did not use dielectrics.

2) Dielectrics introduce additional losses and reduce Q.

3) The Flight Thruster used shaped end plates with a narrow band Rf source.

4) Flat end plates can be used with wideband magnetrons.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Online Rodal

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Please remember this is a long thread and this site's forum has a high signal to noise factor.
...
It would also be helpful if people wouldn't reproduce a whole quotation, but just the sentence that is being responded to.  Anyone interested in reading the whole original post can click on the quote to see the original post, so the whole post doesn't need to be posted again (many times the original post being quoted is just above the response).   The use of ellipsis (...) reduces bandwidth and makes a page cleaner. :)

Offline TheTraveller

OK all good points.  But it is not at all clear that one wants a high Q.

The highest thrust was achieved by Prof. Yang with an effective Q of only ~1500 (take into account that the reported Q's appear much larger because of the unorthodox way the Chinese report Q, if one uses the same method as in the West, Yang's Q was relatively low).

Todd's theory shows that one doesn't want a huge Q.

So using a mesh would be of research interest, to see what difference it makes., whether it makes no difference, or is worse or better

OK I'm scratching my head. Can't find where the Chinese state higher thrust needs lower Q. Maybe you can find it for me?

Can find it stated for the 4 modes examined, higher Q = higher thrust as attached:
http://www.emdrive.com/NWPU2010translation.pdf

Think I'll follow the data and go for high Q. ;)
« Last Edit: 05/19/2015 01:45 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Online Rodal

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OK I'm scratching my head. Can't find where the Chinese state higher thrust needs lower Q. Maybe you can find it for me?
...
What I stated was

...The highest thrust was achieved by Prof. Yang with an effective Q of only ~1500 (take into account that the reported Q's appear much larger because of the unorthodox way the Chinese report Q, if one uses the same method as in the West, Yang's Q was relatively low)...

Hat-tip to Star-Drive and Zen-In for first uncovering this fact about Prof. Yang's tests

____

TheTraveller: the Q's you posted are not calculated the same way as Shawyer and people in the West calculates them.   Apples and Oranges
« Last Edit: 05/19/2015 01:50 AM by Rodal »

Offline TheTraveller

...
OK I'm scratching my head. Can't find where the Chinese state higher thrust needs lower Q. Maybe you can find it for me?

Can find it stated for the 4 modes examined, higher Q = higher thrust as attached.
What I stated was that Prof. Yang has achieved the record highest thrust recorded for the EM Drive and that the Q's she conducted the experiments at (when calculated the same way as they are calculated in the West) are low Q~1500 when compared to Shawyer's Q (hat tip to Star-Drive and zen-in for first uncovering this)

I have read the 3 papers many times. Where did she state that? In what table? The 2010 paper I linked and the attached table makes it VERY clear the highest thrust came with the highest Q.

BTW I doubt you can get a good frustum Q measurement using a broadband microwave source as the frequency is all over the place and not at 2.45GHz. So the observed bandwidth would be as wide as a barn door because the wide band magnetron output is as wide as a barn door.

Shawyer does say that if using flat end plates, to use a magnetron because of the wide frequency output. So if you want to use a maggie as the Rf generator, use flat end plates and thus have lower Q than if you had shaped end plates and a narrow band Rf source. Nothing here says it is better to have lower Q to get higher power. It is about pragmatic engineering. Making do with what you have to get the best result, even if you know there is a better way.

I see now this was your assumption and not from the paper.

Again I state that if you read the 2010 paper, it is VERY clear the higher the Q, the higher the thrust. Nothing the Chinese nor Shawyer has presented goes against that.

As to how to get a frustum that has constantly varying internal wavelengths to resonate at each end plate, from a different applied Rf wavelength, well I'm working on that. Might be my secret squirrel secret sauce.
« Last Edit: 05/19/2015 02:02 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Online Rodal

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I have read the 3 papers many times. Where did she state that? In what table? The 2010 paper I linked and the attached table makes it VERY clear the highest thrust came with the highest Q.

BTW I doubt you can get a good frustum Q measurement using a broadband microwave source as the frequency is all over the place and not at 2.45GHz. So the observed bandwidth would be as wide as a barn door because the wide band magnetron output is as wide as a barn door.

I see now this was your assumption and not from the paper.

Again I state that if you read the 2010 paper, it is VERY clear the higher the Q, the higher the thrust. Nothing the Chinese nor Shawyer has presented goes against that.

Well it may help to read them again, and to recalculate the Q in Yang's tables the way Q is calculated in the West  :)

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369553#msg1369553

Particularly read Prof. Yang's most recent paper containing the embedded thermocouple temperature measurements, that spell this out very clearly.

Kudos to zen-in by computing the Q correctly, and to Star-Drive for first uncovering this fact.
« Last Edit: 05/19/2015 03:14 AM by Rodal »

Offline TheTraveller

...
I have read the 3 papers many times. Where did she state that? In what table? The 2010 paper I linked and the attached table makes it VERY clear the highest thrust came with the highest Q.

BTW I doubt you can get a good frustum Q measurement using a broadband microwave source as the frequency is all over the place and not at 2.45GHz. So the observed bandwidth would be as wide as a barn door because the wide band magnetron output is as wide as a barn door.

I see now this was your assumption and not from the paper.

Again I state that if you read the 2010 paper, it is VERY clear the higher the Q, the higher the thrust. Nothing the Chinese nor Shawyer has presented goes against that.

Well, read them again, and this time please figure out by yourself how Yang calculates the Q in her tables  :)

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369553#msg1369553

Particularly read, in Chinese, Prof. Yang's most recent paper containing the embedded thermocouple temperature measurements, that spell this out very clearly.

What does it matter how the Chinese measured their Q? Their data consistently shows the higher their Q, the higher the thrust. The relationship is clear.

Don't get hung up on how the numbers are calculated. I realise that is hard as you are a numbers guy. Look at the relationships between their Q values and their Thrust values. Is clear the higher the Q, the higher the thrust.
« Last Edit: 05/19/2015 02:08 AM by TheTraveller »
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Offline Fugudaddy

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Quick note on Iulian's test; this was his third attempt. Unless I'm missing something, wouldn't have any thermal effects have shown up on those earlier tests at least in some form or was his measurements not accurate enough to measure that small of an effect?

Not as quick note on the Internet. With all due respect to Dr. Rodal- his characterization of the Internet (http://forum.nasaspaceflight.com/index.php?topic=36313.msg1375139#msg1375139) is a bit inaccurate. Yes, there are plenty of distractions to be had, but to those with developed critical thinking skills, the Internet can be a fantastic tool.

In fact, the Internet was invented *for discussions just like this one*. Scientists getting together to share information and collaborate in new ways across distance and experience. This discussion has been an amazing example of social science application of this tool. Besides Dr. Rodal and the EW team's contributions, there's been several DIYers, mathematicians, skeptics, and scientists of all strips all tossing in ideas.

But then, out of that, there's been WarpTech's now known 'Todd Conjecture'. SeeShell's waveform expertise, seeing microwaves in hot tubs. Iulian's new much-debated video. Contributions from around the world. All the people working together here that have been pushing the literal boundaries of human understanding.

Having watched the Internet grow from it's ARPA/DARPA days in the 70's and 80's through to the ubiquitous tool that it is today, seeing exploration like this happening is an amazing experience; no matter *what* comes of this EM drive experimentation.

Yes, it's a bit like the Tower of Babel come to life, millions of voices all reaching out at once. But the Internet is a tool. And like any tool used in the hands of those with critical thinking skills, it becomes a powerful tool indeed.

Keep up the good work! This is an amazing time in human history to be doing science.

Online Rodal

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...Not as quick note on the Internet. With all due respect to Dr. Rodal- his characterization of the Internet (http://forum.nasaspaceflight.com/index.php?topic=36313.msg1375139#msg1375139) is a bit inaccurate....
Yes I corrected myself in a subsequent message (*):

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1375149#msg1375149

where I say that I agree, with what DYFAN (and you) say about the Internet,

World-wide collaboration in the Internet is a sure plus  :)

______________
(*) I guess that when I wrote the first message I must have been feeling information overload  ;)
« Last Edit: 05/19/2015 03:08 AM by Rodal »

Offline WarpTech

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I have read the 3 papers many times. Where did she state that? In what table? The 2010 paper I linked and the attached table makes it VERY clear the highest thrust came with the highest Q.

BTW I doubt you can get a good frustum Q measurement using a broadband microwave source as the frequency is all over the place and not at 2.45GHz. So the observed bandwidth would be as wide as a barn door because the wide band magnetron output is as wide as a barn door.

I see now this was your assumption and not from the paper.

Again I state that if you read the 2010 paper, it is VERY clear the higher the Q, the higher the thrust. Nothing the Chinese nor Shawyer has presented goes against that.

As to how to get a frustum that has constantly varying internal wavelengths to resonate at each end plate, from a different applied Rf wavelength, well I'm working on that. Might be my secret squirrel secret sauce.

Sorry for the confusion. I was the one that said that optimizing for a higher Q is counterproductive for generating thrust, not Yang. Here is my logic;

The only way the frustum can gain momentum from the EM waves inside is if those waves are attenuated on each cycle, asymmetrically. The Q is the energy stored/loss per cycle. So increasing Q by decreasing the loss per cycle, effectively it MUST reduce the amount of attenuation such that there is less thrust transferred to the frustum. Alternatively, if you increase Q by storing more energy, without altering the amount of power attenuated, then there is more energy in reserve to draw from. If the system used PWM, it could sustain a longer duty cycle.

So there are advantages to higher Q that can produce a higher thrust, but optimizing Q at the expense of reducing the attenuation, will lower the thrust, IMO.

I wonder what, if anything would result if there were a perfectly cylindrical 1/4 wave stub on one side of the source emitter and a frustum at 3/4 wavelength long on the other side of the emitter. The 1/4 wave stub side on the big end would resonate, and the frustum would attenuate. Engineered asymmetry with a much simpler resonant cavity.

Todd D.

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