Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1875772 times)

Offline VAXHeadroom

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It seems that a consensus has emerged, even among EMdrive proponents, that Shawyer's math is wrong and his experiments suspect. Yang's results are suspect because of the poor testing environment and the generally atrocious quality of scientific institutions in China. NASA's results, under the highest quality testing environment of the three significant experimental efforts, also show the smallest measured force (probably within their experimental error, as shown by the test with different device orientation). DIY EMDrivers' results are, so far, all suspect and lack rigor; they will not exceed the standards set by NASA.

So the inventor of this device has little credibility, the positive results from other labs are suspect, null, or insignificant with respect to error, and yet there is still enormous enthusiasm in its development. Herculean efforts are put forth to provide a theoretical basis for data that is too weak to publish in a reputable journal. Why?

Because in the 1/10^9 chance that this effect is real - even to a small degree - it makes spaceflight into a 'whole new ballgame'.  Being able to propel spacecraft without having to carry fuel which is depleted when thrusting is such a HUGE deal that this is worth running to ground.

Example: The LCROSS satellite which found water on the moon in 2009 (full disclosure: I was Lead Flight Software Engineer) had a tank with 330KG of hydrazine.  The whole spacecraft only weighed 600KG fully loaded, so >half the mass was fuel.  So even if we added 100KG for EM thrusters and more solar array and more batteries, we would have been able to save ~200KG of mass.  At a cost of about $20K/KG to launch to low earth orbit, the launch costs would go down $4M.  LCROSS was lunar, so the costs are just about double that - $8M.  The whole program only cost ~$200M including hardware, software, launch and ops - a super cheap satellite.  AND we almost lost the mission because a system design error spewed out most of our fuel when we were out of contact one night.  So, OK, this is a super long shot.  The tantalizing possibility that this just might be a real effect? TOTALLY WORTH EVERY BIT of time and money.
-- Emory Stagmer (aka VAXHeadroom)
Emory Stagmer
  Executive Producer, Public Speaker UnTied Music - www.untiedmusic.com

Offline Rodal

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It seems that a consensus has emerged, even among EMdrive proponents, that Shawyer's math is wrong and his experiments suspect. Yang's results are suspect because of the poor testing environment and the generally atrocious quality of scientific institutions in China. NASA's results, under the highest quality testing environment of the three significant experimental efforts, also show the smallest measured force (probably within their experimental error, as shown by the test with different device orientation). DIY EMDrivers' results are, so far, all suspect and lack rigor; they will not exceed the standards set by NASA.

So the inventor of this device has little credibility, the positive results from other labs are suspect, null, or insignificant with respect to error, and yet there is still enormous enthusiasm in its development. Herculean efforts are put forth to provide a theoretical basis for data that is too weak to publish in a reputable journal. Why?

Why bother?

The answer is obvious.  Because of the huge promise for more affordable and timely space travel if the claims would be true.  Why do people reach for the stars?  Because it is what separates humankind from all other known creatures: the search for knowledge and understanding of the Universe.

“All the universe or nothingness? Which shall it be, Passworthy, which shall it be?



If the EM Drive is an artifact, other people will try (as many are doing now) other means of reaching affordable space travel.  I have faith in humanity and our ability to transcend our world :)
« Last Edit: 06/25/2015 09:39 PM by Rodal »

Offline wallofwolfstreet

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Note that all of these unforeseen challenges don't say zilch about the validity of the phenomenon. They are  the mere vicissitudes of life and experimental physics.

I have to disagree with that.  If there was a strong theoretical basis that predicted the EMdrive, then I would agree that experimental failure means little in terms of whether or not the phenomenon is real.  There is no strong theoretical basis for the Emdrive right now, so the idea that it even exists in the first place is questionable.

Analogy:
Let's say I thought I could jump ten metres high.  I try, and fail.  Maybe the wind direction wasn't right, or I didn't get enough sleep the night before, or I wasn't wearing the right shoes, or I didn't have enough money, or the moon was in the wrong phase, or.....

Or maybe, it is in fact impossible for me to jump ten metres.  It wasn't an issue with my experimental setup.  It's just impossible.

Maybe the reason that Shawyer, after 15 years and 250,000 pounds, hasn't actually presented definite results isn't because of some issue with his method.  Maybe there just isn't anything there?

It's an Occams razor thing.  If I fail to jump ten metres despite all my best efforts, is it because I'm just not doing it right, or because it's just not possible?

Offline matthewpapa

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TheTravellerEMD posted the abstract on reddit: (bold added for emphasis)

Sorry but this is nothing new, sadly. The text of this upcoming abstract is the exact same as in the non peer-reviewed paper presented by Shawyer at the IAC conference, Toronto, Canada, in October 2014. The title was exactly the same BTW. More important, the text was the same. On the SPR web site, only the more vague presentation paper is available, but the full IAC 2014 paper has been posted in the NSF EmDrive thread 2 by Mulletron in this post.


Shawyer, Roger (29 September–3 October 2014). "Second Generation EmDrive Propulsion Applied to SSTO Launcher and Interstellar Probe", 65th International Astronautical Congress (IAC 2014). Toronto, Canada: International Astronautical Federation.

So it appears TheTravellerEMD on Reddit posted the abstract of the 2014 IAC paper??? Or the peer-review 2015 paper is based entirely on the 2014 conference paper? I'm confused.

If the abstract is the same, we should not hold our breath. That conference paper was all about projective study showing theoretical features of a conceptual superconducting EmDrive. No real data or new experimental results from any superconducting test article. I really hope I'm wrong and the 2015 peer-reviewed paper is completely different :(

I don't think many of you has ever read it, so I attach the full IAC 2014 paper below.

[EDIT]: @TheTraveller, can you tell us, just if the upcoming 2015 paper is written on the same grounds as the IAC 2014 paper?


<<The text of this upcoming abstract is the exact same as in the non peer-reviewed paper presented by Shawyer at the IAC conference, Toronto, Canada, in October 2014.>>

You mean, the abstract of the "peer-reviewed paper" that is going "to remove all doubt" is the exact same as the 2014 paper???

Either TheTravellerEMD made a mistake or this is extremely disappointing news to anyone that believed the report that new upcoming results "to remove all doubts" would appear in the upcoming ''peer-reviewed" paper.


 I sincerely hope that  TheTravellerEMD made an innocent human mistake here and confused the 2014 and 2015 abstracts.

But if it is true that TheTraveller had read the upcoming peer-reviewed paper by Shawyer, he/she should certainly be able to tell us whether a mistake was made, or whether the peer-reviewed paper has the same abstract as the 2014 conference paper (this would be very strange as most peer-reviewed reputable journals do NOT accept papers that have been presented at old conferences).


My hunch on this is that Mr. Shawyer simply has failed to produce a workable superconductor Emdrive demonstrator. Ergo, no new results to show.

Either because the superconductor material he is using is too frail, or flimsy or unwieldy and it doesn't result in a stable shape producing the expected Q values for enough time to conduct tests, and therefore, no measurements and no significant thrust increase is evidenced.

Or maybe he doesn't actually have the financial resources to do it on his own.

Note that all of these unforeseen challenges don't say zilch about the validity of the phenomenon. They are  the mere vicissitudes of life and experimental physics.

What is bad PR is to oversell upcoming results and just copy-paste and slightly edit previous results. If he has nothing new, he shouldn't publish the same things as if they were new.

So we should wait on EW & others then?

Unless some DIYer can make their test drive hover or something our best bet is the NASA experiments IMO.

Seems like Eagleworks has produced the highest quality science, with this thread in second place :) . And Eagleworks has every reason to admit that they were wrong if they discover the thrust was an experimental mistake. Still they persist so there is definitely hope

As for all the talk that this is some black project at certain aerospace companies, it was all started by the Traveller so I would take it with a grain of salt given what has happened today.
« Last Edit: 06/25/2015 07:40 PM by matthewpapa »

Offline rfmwguy

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Doc, you have stated TM212 as EW's success, am I correct?
I don't understand the question << you have stated TM212 as EW's success, am I correct?>> please elaborate further

From memory, not from search, I recall you mentioning TM212 mode in regards to EW. Is this the case and did this mode result in "thrust". Otherwise, where did you pick up on this...seems I recall some thermal and modeling images with this mode...many, many pages ago.

OK your memory is perfect.

NASA Eagleworks reported thrust with a HDPE dielectric insert, with mode TM212 at a lower frequency (1.94 GHz instead of 2.45 GHz).

Please notice that they used a dielectric insert, while you are not planning to use a dielectric insert.

The problem is that NASA also reported thrust with mode TE012 with a dielectric insert (at 1.8804 GHz), but they reported zero, nada, zilch, with TE012 without a dielectric insert (at 2.168 GHz).

Look here:
http://emdrive.wiki/Experimental_Results

Thanks, now we're getting somewhere. Julian had a TM212, 6.25 x 11 x 9.0L without resonance and measured an "effect" both vertical and horizontal...which is what I will do. His experiments are on hold at the "tuner" plate stage designed to increase L.

So, what I will do is vary the rf injection points at midway, 1/4 wave to top and 1/4 to bottom plate. If null results, I may consider a "top hat" tuner...or I might go back to writing another book...its been 3.5 years now ;^)

Offline deltaMass

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Shawyer's abstract talks about SSTO (single stage to orbit) tech from a collection of EmDrives of new design. Let's pick that apart.

The key spec is the ability for an EmDrive to lift itself and all its support (power, electronics, etc.) off the ground. Specifically F/m > g, or the thrust-to-mass ratio must exceed 9.81 m/s2.
If one EmDrive cannot lift itself, then any greater number of them in constellation cannot do it either, unless substantial weight savings accrue from  sharing  the electronics and RF delivery system.

What I'm interested in here is the "blockbusterishness" of this new paper - i.e. how much better does it have to be than the already-published performances he has reported?

Shawyer mentions a small number (<10) so let's cut him some slack and say he uses 10 to implement a SSTO. Let's roughly handwave to say each drive of his already-published data produces 1 Newton (it's actually less than that) from a 5 Kg cavity (generously light) and that the ancillaries weigh 50 Kg, considered shared. Then the all-up weight is 100 Kg and the total thrust is 10 N. Thus this already-published guesstimate yields 0.1 N/Kg, and that is extremely generous. The lift-off requirement is at least 10 N/Kg.

Thus the blockbuster factor that Shawyer is claiming in this new paper is at least a factor 100x improvement over already-published designs.

Please, for the record, register my blank disbelief. Please register also my opinion that this is a pack of lies.
« Last Edit: 06/25/2015 08:03 PM by deltaMass »

Offline SeeShells

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It seems that a consensus has emerged, even among EMdrive proponents, that Shawyer's math is wrong and his experiments suspect. Yang's results are suspect because of the poor testing environment and the generally atrocious quality of scientific institutions in China. NASA's results, under the highest quality testing environment of the three significant experimental efforts, also show the smallest measured force (probably within their experimental error, as shown by the test with different device orientation). DIY EMDrivers' results are, so far, all suspect and lack rigor; they will not exceed the standards set by NASA.

So the inventor of this device has little credibility, the positive results from other labs are suspect, null, or insignificant with respect to error, and yet there is still enormous enthusiasm in its development. Herculean efforts are put forth to provide a theoretical basis for data that is too weak to publish in a reputable journal. Why?

Because I choose to dream.
 
I believe we are at a cusp of our growth on this ball of mud and if we don't evolve from this tiny seed called earth we may perish and never know the glorious heights that await us, or the true challenges of a universe that has no bounds. Yes, I dream, for humanity.

Shell

Offline tchernik

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Note that all of these unforeseen challenges don't say zilch about the validity of the phenomenon. They are  the mere vicissitudes of life and experimental physics.

I have to disagree with that.  If there was a strong theoretical basis that predicted the EMdrive, then I would agree that experimental failure means little in terms of whether or not the phenomenon is real.  There is no strong theoretical basis for the Emdrive right now, so the idea that it even exists in the first place is questionable.

Analogy:
Let's say I thought I could jump ten metres high.  I try, and fail.  Maybe the wind direction wasn't right, or I didn't get enough sleep the night before, or I wasn't wearing the right shoes, or I didn't have enough money, or the moon was in the wrong phase, or.....

Or maybe, it is in fact impossible for me to jump ten metres.  It wasn't an issue with my experimental setup.  It's just impossible.

Maybe the reason that Shawyer, after 15 years and 250,000 pounds, hasn't actually presented definite results isn't because of some issue with his method.  Maybe there just isn't anything there?

It's an Occams razor thing.  If I fail to jump ten metres despite all my best efforts, is it because I'm just not doing it right, or because it's just not possible?

While I agree MR. Shawyer's behavior is suspect, I won't reject all the other experimental results just because the potential discoverer of the phenomenon has failed to deliver on his grandiose promises. By experimental replication, the other results suggest there is a real phenomenon behind them. Even if we are not sure that phenomenon is what we think it is.

For all we know, the phenomenon could be just a really awesome artifact of measurement due to thermal/electromagnetic interaction effects. It has to be awesome, because it has defied lots of explanations from very smart people around here and elsewhere.

Or it could exist but Shawyer could be wrong in his (rather self-serving) projections of strong force scalability, and it could only work at very low thrust levels (yet orders of magnitude bigger than a photon rocket). Most people agree his maths are bollocks anyway.

But the fact remains he could have found something worthy of investigation, even if his theoretical understanding of it is completely wrong.

People here have suggested several other parameters to explore as potential ways to increase thrust. Until the experiments are done, we can't know if such things could take this into other potential directions.
« Last Edit: 06/25/2015 10:22 PM by tchernik »

Offline Rodal

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I'm not the only active NSF member who has the paper.

Interesting and I think that answers the matter for now.
It certainly doesn't answer the question raised by WallofWolfStreet.  If anything it raises further questions.  What other NSF member has access to the paper and why is that relevant to this thread?

There is only one NSF member (to my knowledge) that disclosed his/her access to Shawyer's paper.

What is the purpose of posting (unasked by anyone) that she/he had privileged access to Shawyer's upcoming paper and boasting about its contents  "it will remove all doubt"  and now posting that another unnamed NSF member also has access?

Why give that irrelevant hearsay information (that somebody else has access to an unpublished paper) instead of providing substantive technical  information on what is the subject matter of the paper?

This is not a thread to disclose who has access to unpublished papers.  This is a thread to discuss the EM Drive developments - related to space flight applications -

This is another example of the disruptive thread-hijacking of the Travellers' posts.  Earlier I complained about his persistent spam posts and empty promotion of Shawyers' dubious experiments.   Whenever he has been asked to clarify one of his claims we just get the run-around.   This really reflects poorly on Shawyer and has further impugned his credibility.   I don't know if Shawyer is paying this guy but I would venture to say he is not getting his money's worth if that is the case.
This whole clumsy episode (if indeed he/she has not made an innocent mistake and confused the 2014 abstract with the 2015 paper -- which is hard to believe if one accepts the claim that she/he had access to the paper prior to peer-review and publication) is actually quite damaging to the credibility of the EM Drive.

So, the chasm between what is purported as the 2015 abstract (identical to the 2014 conference) and what was claimed was going to be revealed "removing all doubts" is unfathomable and difficult to understand.

Offline tchernik

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I'm not the only active NSF member who has the paper.

Interesting and I think that answers the matter for now.
It certainly doesn't answer the question raised by WallofWolfStreet.  If anything it raises further questions.  What other NSF member has access to the paper and why is that relevant to this thread?

There is only one NSF member (to my knowledge) that disclosed his/her access to Shawyer's paper.

What is the purpose of posting (unasked by anyone) that she/he had privileged access to Shawyer's upcoming paper and boasting about its contents  "it will remove all doubt"  and now posting that another unnamed NSF member also has access?

Why give that irrelevant hearsay information (that somebody else has access to an unpublished paper) instead of providing substantive technical  information on what is the subject matter of the paper?

This is not a thread to disclose who has access to unpublished papers.  This is a thread to discuss the EM Drive developments - related to space flight applications -

This is another example of the disruptive thread-hijacking of the Travellers' posts.  Earlier I complained about his persistent spam posts and empty promotion of Shawyers' dubious experiments.   Whenever he has been asked to clarify one of his claims we just get the run-around.   This really reflects poorly on Shawyer and has further impugned his credibility.   I don't know if Shawyer is paying this guy but I would venture to say he is not getting his money's worth if that is the case.
This whole clumsy episode (if indeed he/she has not made an innocent mistake and confused the 2014 abstract with the 2015 paper -- which is hard to believe if one accepts the claim that she/he had access to the paper prior to peer-review and publication) is actually quite damaging to the credibility of the EM Drive.

So, the chasm between what is purported as the 2015 abstract (identical to the 2014 conference) and what was claimed was going to be revealed "removing all doubts" is unfathomable and difficult to understand.

I have to say that if he wanted to throw the Emdrive's interest community into disarray, he has pretty much succeeded (look at reddit's /r/Emdrive reaction).

Weird how over-enthusiasm sometimes achieves quite the contrary of its apparent intentions.

Offline CraigPichach

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New questions -

If one wants to attempt a Q-thruster/EM-Drive at 100kW most commercial units are ~915MHz as opposed to the 2.45Gz of the current experiments. Can one just design for TE012 at 915MHz and expect thrust or is there something inherent to the 2.45Gz? There was a slide on-line from Eagleworks with a 17" OD (long side) and 28" length; is that designed for TE012 at 2.45GHz or 915MHz?

Why is everyone going 2.45Gz, does that have something to do with the resonance frequency of the copper, in which case 915MHz would not work? Or would going 915MHz make it simply too difficult to tune?




Offline deltaMass

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Something that at least @frobnicat will appreciate - can we build an overunity device (free energy, perpetual motion, you know the drill) with the current crop of EmDrives?

The answer is - maybe, but not on Earth; only in space.

A generous k-value looks like about 2*10-4 N/W.
That corresponds to a breakeven velocity of 10 Km/s.
That's a problem for a terrestrial rotator, I think. No - actually I know it is  8)

But in space we can make the radius arm as big as we like.
Let's say that we can engineer a complete EmDrive system to withstand 100 gee.
Then the breakeven radius is 100 Km.
That's pushing it, but not completely beyond the bounds of possibility.

The hub would be anchored at a mountain top on the Moon and the plane of rotation would be horizontal.
« Last Edit: 06/25/2015 09:23 PM by deltaMass »

Offline WarpTech

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In this case, the "water" is the energy stored inside at frequency "f" and energy "Q". When the frustum is pulled forward the mode moves to a lower frequency and lower energy, making the internal mass lighter. It gives up its energy as thrust, (applied energy - internal energy shift) When it is pushed backwards, it adds its energy as resistance, meaning as extra mass. (energy applied + internal energy shift) to cause resistance.

This is very important! Because this is the how it can work as a sealed cavity AND act as a thruster. What needs to be calculated using Maxwell's equations and @Rodal's solution, is how those modes and Q are affected when in an accelerated frame of reference. Maxwell's equations can certainly tell us the energy shift due to the Doppler shift and change in position inside the frustum. This difference between energy shift forward vs energy shift backwards gives us the Delta-Mass! i.e, we solved Woodward's dilemma of how to amplify the effect. :)
Todd

Is the following another way to explain it?

Looking at the TE mode for a cylindrical cavity (https://en.wikipedia.org/wiki/Microwave_cavity), the frequency is (roughly) inversely proportional to the radius of the cavity. Decreasing the radius will increase the frequency, which in turn increases the momentum of light in the cavity. To satisfy conservation of momentum, the cavity has to push back against decreasing the radius. In the other direction, increasing the radius will lower the frequency and momentum of light stored in the cavity. To satisfy conservation of momentum, the lost momentum goes towards encouraging the radius to increase. If the radius is fixed, then the momentum inside the cavity will remain constant.

By having light resonate in a frustum, the change of radius is tied to acceleration along the axis of the frustum. The frustum will thus encourage pushing against its large end (increasing the cavity's radius) and resist pushing its small end (decreasing the cavity's radius). If the frustum does not accelerate along its axis, the radius will not change and no force will be observed.

Here is Notsosureofit's analysis:

http://emdrive.wiki/@notsosureofit_Hypothesis

I've been looking at it. He has the right idea, but his Math procedure is not correct. The force IS dependent on Q/R^2, but his equation is written as a difference in force rather than a difference in potential energy. I think he subtracted where he should've integrated.
Todd

Offline graybeardsyseng

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New questions -

If one wants to attempt a Q-thruster/EM-Drive at 100kW most commercial units are ~915MHz as opposed to the 2.45Gz of the current experiments. Can one just design for TE012 at 915MHz and expect thrust or is there something inherent to the 2.45Gz? There was a slide on-line from Eagleworks with a 17" OD (long side) and 28" length; is that designed for TE012 at 2.45GHz or 915MHz?

Why is everyone going 2.45Gz, does that have something to do with the resonance frequency of the copper, in which case 915MHz would not work? Or would going 915MHz make it simply too difficult to tune?

I believe the focus on the 2.45 Ghz area comes from the availability of resonably priced i.e. cheap magnetrons from microwave oven designs.   I have been thinking about the 915 Mhz range myself.  Either that or go the other way and jump to IR and run it on a 10.6 um C02 laser (100w laser tubes with power supply are available on Ebay etc for under $1K - they are from the plethora of laser engraver/cutters now available so that is an area which might be useful to check.   

However, I would not feel responsible if I didnt add the following:

WARNING - High Power CO2 LASERS (or any high power LASER) are at least as dangerous and often MUCH MORE dangerous than high power RF.  It is a collimated coherent beam of energy.   100ws into a narrow spot will remove body parts before you know it.   I have worked with high power RF and Lasers quite a bit over the years and basically all the warnings on these threads are real and not to be taken lightly.    Laser safety involves series  interlocks on main power and careful attention to spectral reflections.   We once burned out a $500K sensor with the reflection of a carelessly discarded soda can (the bottom of them are very nice reflectors).  That was with a 10 watt CO2 laser.  Just be very very careful.

Herman
EMdrive - finally - microwaves are good for something other than heating ramen noodles and leftover pizza ;-)

Offline arc

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TheTravellerEMD posted the abstract on reddit: (bold added for emphasis)

AND INTERSTELLAR PROBE
Roger Shawyer C.Eng.MIET.FRAeS
SPR Ltd, United Kingdom
sprltd@emdrive.com
ABSTRACT
In an IAC13 paper the dynamic operation of a second generation superconducting EmDrive thruster was described.
... snip

Thats not new!  Has traveller got the wrong info?.
Thats an old paper fom 2014 {_IAC-14-C4,8.5_} iacpresentation.pdf

« Last Edit: 06/25/2015 10:20 PM by arc »

Offline RonM

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A functioning EM drive would be a big technological advance and is worth the effort. Especially since there really isn't a lot of effort compared to most cutting edge physics experiments. As several of you know, it's a table top experiment that skilled hobbyists can do. We're not talking CERN and the LHC.

Now I'm a skeptic, but I'll believe good data. That's what experimentation is all about. If it's a null result, so be it. If there is thrust, let the theorists try to figure it out while we're building EM drives.

To everyone out there building an EM drive to test, good luck, be safe, and get results above the SNR. Let's get some data to settle this issue.

Offline Rodal

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...

Yes, I now have conflicting dimensions, however, am not even sure that "resonance" is key to the success of the thing. One would have to assume that max Q = max resonance to a large degree...some think Q may not be an overiding factor. So little real data from industry is being shared right now, we're on this path with a single flashlight. So be it in the initial stages of development...(  )it happens.

I'd venture to say that this "project" does not have billion-dollar implications, it has trillion-dollar implications IF the device can be scaled and replicated. What we have here is what the brit papers are saying...potential for revolutionizing the aerospace/transport industry. Naturally, anything being done by capitalists eager on getting a slice of the pie will be hidden BEHIND CLOSED DOORS...been there.

Here's one thing my aerospace marketing instincts tell me...if this "effect" was bogus, many companies would have officially said so...with test results. All we have now is theoretical naysayers claiming such, but not one, to my knowledge has completed nor commissioned a build, so sure of their own belief system.

I'll go with 6.25 x 11.01 x 9.91L and let the chips fall where they may. I appreciate all the help at getting to this decision stage.

bigDiameter = 11.01 inches;
smallDiameter = 6.25 inches;
axialLength = 9 inches;  NOTICE 9 inches -- in this case

with FLAT ENDs with a TRANSVERSE MAGNETIC MODE.  It resonates at 2.45032 GHz with TM212


////////////////////////////////

bigDiameter = 11.01 inches;
smallDiameter = 6.25 inches;
axialLength = 10.2 inches;  NOTICE 10.2 inches -- in this case

with FLAT ENDs with a TRANSVERSE ELECTRIC MODE.  It resonates at 2.45044 GHz with TE013

////////////////////////////////

(Note: my previous calculation for 9.91 inches for TE013 resonance was using SPHERICAL ENDS)

L = 9.91 inches with spherical ends will resonate at TE013 at 2.45 GHz

L = 9.91 inches with flat ends will resonate at TE013 at 2.48468 GHz

So that you have a better idea of where to locate the RF feed, here are the shapes of the non-uniform waves and  the locations of the maxima of the wave for the TE013 case with the cavity resonating at 2.45 GHz.

If you want to excite the free-free bending vibrations of a beam in space, where is best to hang it from? from the nodes or from the maxima?  (answer: from the nodes, but the following video shows that even when hanging it at non-optimal locations, it still resonates -albeit at a lower amplitude-)



I think you want to locate the RF Feed antenna close to the maxima, similar to the excitation being placed near the maxima at the ends in the above video.  It would be foolish to place the RF feed antenna at a node of the wave.

The wave pattern in a truncated cone is not a sinusoidal curve, therefore it is not governed by equi-distant half-wavelengths as sines are in cylindrical cavities.  People should not assume that the internal nodes in a truncated cone are spaced equidistant from each other.  They are not.
« Last Edit: 06/26/2015 07:01 AM by Rodal »

Offline vulture4

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All we have now is theoretical naysayers claiming such, but not one, to my knowledge has completed nor commissioned a build, so sure of their own belief system.
I am all for testing and trying out this idea. But I think it is unfair to say doubt is based only on a belief system. I've carefully reviewed the available papers, with or without peer review, and discussed the ideas with physicists who would dearly love to have a reactionless drive. The difficulty is that there are errors in the theoretical rationale and in the experimental procedures. I am trying to get the money together for a simple test of the thermal recoil effect, i.e. the apparent thrust produced by unequal heating, using resistance heating only (no RF) at various pressures between atmospheric and vaccuum. Test results are useless unless errors are carefully measured.

Really though, theory must come first. An experiment is only useful in physics when a solid theoretical foundation is developed first. That doesn't mean the exact results of the experiment can be predicted, i.e. no one knew exactly what mass the Higgs boson would have. But the theory underlying it was so solid there was almost no doubt the particle existed. Similarly, the first demonstration of the Casimir effect was considered almost routine, since its existence was so well based in physical theory.
« Last Edit: 06/25/2015 11:08 PM by vulture4 »

Offline tchernik

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All we have now is theoretical naysayers claiming such, but not one, to my knowledge has completed nor commissioned a build, so sure of their own belief system.
I am all for testing and trying out this idea. But I think it is unfair to say doubt is based only on a belief system. I've carefully reviewed the available papers, with or without peer review, and discussed the ideas with physicists who would dearly love to have a reactionless drive. The difficulty is that there are errors in the theoretical rationale and in the experimental procedures. I am trying to get the money together for a simple test of the thermal recoil effect, i.e. the apparent thrust produced by unequal heating, using resistance heating only (no RF) at various pressures between atmospheric and vaccuum. Test results are useless unless errors are carefully measured.

Really though, theory must come first. An experiment is only useful in physics when a solid theoretical foundation is developed first. That doesn't mean the exact results of the experiment can be predicted, i.e. no one knew exactly what mass the Higgs boson would have. But the theory underlying it was so solid there was almost no doubt the particle existed. Similarly, the first demonstration of the Casimir effect was considered almost routine, since its existence was so well based in physical theory.

IANAP, but isn't all of physics based on empiricism and falsifiability of theories? theory, when it's mature, can produce predictions that can be tested against reality in the way you say. But some times, phenomena are just found out or stumbled upon.

It's like fire. Primitive humans saw it, figured out how to start it (replicate it), keep it alive (for proving its existence and their dominion upon it to others), and used it for millennia before we had the slightest idea what oxygen and combustion were.

That bit of "theory must come first" smacks me as a snobbish and fundamentally wrong philosophical position; one unfriendly towards new phenomena and discoveries that don't follow the protocol.
« Last Edit: 06/25/2015 11:12 PM by tchernik »

Offline rfmwguy

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INCORRECT QUOTATION, QUOTING ME INSTEAD OF THE AUTHOR OF WHAT IS BEING QUOTED
I am all for testing and trying out this idea. But I think it is unfair to say doubt is based only on a belief system. I've carefully reviewed the available papers, with or without peer review, and discussed the ideas with physicists who would dearly love to have a reactionless drive. The difficulty is that there are errors in the theoretical rationale and in the experimental procedures. I am trying to get the money together for a simple test of the thermal recoil effect, i.e. the apparent thrust produced by unequal heating, using resistance heating only (no RF) at various pressures between atmospheric and vaccuum. Test results are useless unless errors are carefully measured.

Really though, theory must come first. An experiment is only useful in physics when a solid theoretical foundation is developed first. That doesn't mean the exact results of the experiment can be predicted, i.e. no one knew exactly what mass the Higgs boson would have. But the theory underlying it was so solid there was almost no doubt the particle existed. Similarly, the first demonstration of the Casimir effect was considered almost routine, since its existence was so well based in physical theory.

Why are you quoting me for something I did not state ? Please correct your quotation

Yes, this is my commentary. I think the push to experiment has been to challenge questionable theories on BOTH sides. Best I can tell is these theories/counter theories have been going on for decades and some of us are impatient. As someone else said, if null, so be it. The results of every experiment will undoubtedly dissapoint someone...Funny, I have no emotional attachment to the results, only the curiosity to experiment...weird, I know.

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