Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1800569 times)

Offline aero

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A gas is a compressible fluid and as such describable by fluid dynamics, just a different constitutive law.  Different fluids have different constitutive laws.
True.

What this video shows is light waves consisting of photons traveling as waves down a long conical fiber optic cable (right to left) that causes them to frequency shift as they loose resonance and then decay into traveling evanescent waves outside of the fiber optic walls.  These evanescent waves carry momentum and spin components that are orthogonal to the direction of wave propagation. Those components of momentum and spin outside of the walls of the fiber optic cable effect the fluid inducing movement along the length of the optic cable.

I have a conical frustum analogous to the tapered fiber optic that induces the same actions in the frustum. The collapsing modes and waves decay into evanescents just like the fiber optic. My question would be what happens to that spin and momentum of that high Q wave as it collapses into the end or sidewalls of the cavity? Mediums are different but it's still photons and waves.

Oh - So if you bundle a bunch of them together and run them in air at the right frequency, then the evanescent waves will push the air molecules along - toward which end? And if you run them in vacuum they will push the photons along?
Retired, working interesting problems

Offline TheTraveller

I won't waste my time in calculating the exact number based on your definition of length since from your answer it is evident that you don't care, and I have better things to do.

If I didn't care I would not have taken the time to explain what length means to frustum resonance.

My resonance, at TE013, for the Mark 2 frustum design as below is 2.45GHz and not 3.9GHz.
I deleted the post with the calculations since they were based on an incorrect length.  I wish I could take the time back that I wasted in those calculations and posting them. 

Good luck with your design at whatever frequency you decide to make it (at one point 3.9Ghz then it was 2.45GHz, then it was 1.9Ghz because of BlueTooth and now is back to 2.45 GHz ?, it doesn't matter to me :) )

The 1.9GHz was for a possible verification at Eagleworks. If I have a reliable EMDrive and Eagleworks wish to test it, will send my entire system, including Rf amp and control system, so no need to make my EMDrive compatible with their Rf system.

The 3.9GHz was for the Flight Thruster estimated dimensions.

I do appreciate your efforts. At least now we are talking the same length.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Online Rodal

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Which, by the way is an issue when defining the dimensions for Tajmar since he also uses spherical ends.  What "length" did he measure ?  Unless Tajmar provides a drawing for the dimensions he gave, particularly what he means by "length", it is also subject to misinterpretation. This is much more of an issue for spherical ends than for flat ends.  To be technical about it, when people use spherical ends, they should ONLY give the following dimensions:


small spherical radius of curvature = r1
big spherical radius of curvature = r2
cone half-angle = theta

Nothing else.  Giving "lengths" for spherical ended EM Drive is subject to misinterpretation.  The radii of curvature of the spherical ends should be given, rather than assumed.  That is standard convention for engineering drawings when giving curved surfaces.  Spherical ends are fabricated on the basis of knowledge of their radii of curvature and not based on extraneous calculations to derive the radii of curvature.

When r1, r2, and theta are given, nothing else is needed.

It is standard convention for engineering drawings never to give superfluous dimensional data.
« Last Edit: 08/04/2015 05:15 PM by Rodal »

Offline ElizabethGreene

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />

Online Rodal

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />


Elizabeth, this is very important news, as many of us have suspected that the EM Drive is NOT a closed system and that "thrust" may be explainable by what is leaking.

Looking forward to what you measure :)
« Last Edit: 08/04/2015 05:13 PM by Rodal »

Offline TheTraveller

Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />

Good advise.

Please share your dimensions, frequency and excitation mode as then I'll run a set of number for you.

How do you know you have resonance?

Are you using a magnetron or narrow band Rf amp?

What wattage?

Thanks for your reply and good luck.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline SeeShells

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A gas is a compressible fluid and as such describable by fluid dynamics, just a different constitutive law.  Different fluids have different constitutive laws.
True.

What this video shows is light waves consisting of photons traveling as waves down a long conical fiber optic cable (right to left) that causes them to frequency shift as they loose resonance and then decay into traveling evanescent waves outside of the fiber optic walls.  These evanescent waves carry momentum and spin components that are orthogonal to the direction of wave propagation. Those components of momentum and spin outside of the walls of the fiber optic cable effect the fluid inducing movement along the length of the optic cable.

I have a conical frustum analogous to the tapered fiber optic that induces the same actions in the frustum. The collapsing modes and waves decay into evanescents just like the fiber optic. My question would be what happens to that spin and momentum of that high Q wave as it collapses into the end or sidewalls of the cavity? Mediums are different but it's still photons and waves.

Oh - So if you bundle a bunch of them together and run them in air at the right frequency, then the evanescent waves will push the air molecules along - toward which end? And if you run them in vacuum they will push the photons along?
Honestly aero I'm not sure what's going to happen or quite how or what they will interact with inside or outside the cavity or if it's actions within the cavity itself. All I know is that it seems to be a red flag that in many ways makes more sense than some other theories. Who knows aero it may dovetail into one of those theories. I think it would be negligent on my part as a builder to not look at this effect.

It's interesting in the video the cells move towards the large end which means its thrust direction is just like a frustum's.

Offline SeeShells

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />

Good advise.

Please share your dimensions, frequency and excitation mode as then I'll run a set of number for you.

How do you know you have resonance?

Are you using a magnetron or narrow band Rf amp?

What wattage?

Thanks for your reply and good luck.
All I ask is for you to be safe. If you would like I'll fed-ex my little USB SA overnight as long as you return it when you get yours.

Shell

Offline LasJayhawk

An inexpensive microwave leak detector might be a good thing to have

http://www.amazon.com/dp/B0027AIL7A/ref=cm_sw_r_tw_dp_PFpWvb1A9M115ia

Online Rodal

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Inexpensive Microwave Leakage Detectors - Are They Worth It? (A Performance Evaluation Report)
Journal of Microwave Power and Electromagnetic Energy, 46 (3), 2012, pp. 128-138.

Robert F. Schiffmann
RF Schiffmann Associates, Inc. 149 West 88th Street New York, NY 10024, USA
Rupert Steiner
Gigatherm AG, Postfach Halten 120 CH-9035 Grub AR Switzerland
Received: July 10, 2012
Accepted: September 8, 2012

<<Due largely to the misinformation spread by the blogosphere, many consumers are
worried they may be harmed by the radiation leaking from microwave ovens. As a result,
many have been purchasing and using inexpensive microwave oven leakage detectors. Several
microwave engineers have tested some of these and found them to be inaccurate, often giving
false-high or false-low readings. In our study, we examined a number of these selling for USD
79.95 and less, by comparison to professional equipment.>>

<<CONCLUSIONS
Some of the inexpensive instruments
show far too low readings, which may be
a serious safety problem: too low readings
make users feel safe even while standing in
front of a leaky oven.
Some of the inexpensive instruments
show far too high readings, which is a serious
image problem for microwave industry: too
high readings make users think that nearly
every microwave oven is dangerous even
though they are not.
Some of the inexpensive instruments
show readings strongly dependent on how
the sensor tip of the instrument is held or
rotated along its axis, which is a serious
image problem for microwave industry:
such dependencies make users lose their
confidence in microwave ovens and
measurement equipment in general. >>

http://www.jmpee.org/jmpee_site/Vol_46(3)/JMPEE46-3-128Shiffmann.pdf

Note: This manuscript is a full peer-reviewed
manuscript version of a conference
proceeding presented at 46th IMPI Annual
International Symposium in Las Vegas, NV,
June 20-22, 2012
« Last Edit: 08/04/2015 05:57 PM by Rodal »

Offline ElizabethGreene

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Quote
All I ask is for you to be safe. If you would like I'll fed-ex my little USB SA overnight as long as you return it when you get yours.

Shell

Thank you for the offer.  I'm safe.  I found this when my safety meter http://amzn.to/1P4p6pP _inside_ the faraday cage triggered.

Answering the other questions:
I'm still in the play-to-find-out-what-I-don't-know-phase.  This test was to make sure I had the electronics on the magnetron working properly.  It was in my 0.2a cavity that didn't have resonance near 2.45e9.  I will happily beg for assistance and share when I get my 101 stuff worked out.

Here's another bit for experimenters.  If you pry the bottom cover off your magnetron you'll see a couple of ferrite cored coils.  Those are the feed for the filament [the heater] that sources the electrons in the magnetron.  If you're following the "Make a magnetron a low noise RF source" paper, that's the bit where you cut the power after it warms up.  You don't have to disassemble any of the vacuum sealed bits of the tube.

Offline ElizabethGreene

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Inexpensive Microwave Leakage Detectors - Are They Worth It? (A Performance Evaluation Report)
Journal of Microwave Power and Electromagnetic Energy, 46 (3), 2012, pp. 128-138.

Very nice.  I have Instrument #3, and will take it with a large grain of salt in the future.

Offline SeeShells

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />


Elizabeth, this is very important news, as many of us have suspected that the EM Drive is NOT a closed system and that "thrust" may be explainable by what is leaking.

Looking forward to what you measure :)
Just as long as she stays safe Jose, that's the most important thing. Everytime the plasma would arc in rfmwguy's I'd mentally cringe, even though I know he know what he is doing.

Interesting she thinks it's evanescent wave actions because of the decay. I'm excited to be honest.

Shell 

Offline A_M_Swallow

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Thanks, I think I've narrowed down the theory candidates over the past week. Plotting what would be the phase velocity in what I posted above, it appears there is a significant boost in thrust-to-power ratio if we allow the small end to be much smaller than the big end, like  1/10th the size. Basically, thrust depends almost entirely on the side wall force, not the small end. We want to maximize force on the walls, like @Rodal's plot below. It also seems, operating at around 100MHz, is not an unmanageable model either.
Todd
 

100MHz is a nice frequency range to deal with but it is bang in the middle of the UK's civilian FM radio range (87.5 - 108MHz). Anyone using a leaky Faraday cage with a kW magnetron in that frequency range will probably receive legally enforceable complaints about interference.

Does around 100MHz mean the resonate frequency of the frustum in the EM Drive can be designed to be say 110MHz or 120MHz or 200MHz or 75MHz?

It is currently early August 2015, so the FCC, Ofcom (UK) and overseas regulators can still give 'suggestions' for a suitable frequency range before new thrust frustums are made. They will have to allow for air at 1 atmosphere, low pressure nitrogen and the vacuum of space when choosing a range.

Anyone can ask a regulator for advice but to be taken seriously a formal request to reserve a frequency range for spacecraft thrusters probably has to come from an authority such as NASA. If the government delays too long all the EM Drives will say "Made in China" and use a frequency chosen by the Chinese Government.

Offline X_RaY

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />
You can use copper adhesive tape to easy fix any leakage :)
http://www.iccfl.com/index.php?cPath=135_184&osCsid=ur8g03ipgtkkdh6src34otdh84
« Last Edit: 08/04/2015 06:28 PM by X_RaY »

Offline rfmwguy

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Thermal tests done including 5 minute run at 30% power, which is what I'll use for fulcrum test. What I learned: Matching into frustum is good, magnetron ran at temperatures well below 200C. Still had minor arcing, corrected it with full teardown and replacement of Db with mesh only, no copper clad. IOW, frustum is now all mesh except for Ds where magnetron is mounted. There was no arcing on Ds throughout any thermal testing. Plasma focused on Db, interestingly enough diagonally across from radome, not directly across axially.

Here's the video, time to do yard work, oh joy:


Looks good.

One thing that bothered me was the rapid changes in temperature measured by the IR thermometer when the magnetron was running. Could there be interference causing issues with the thermometer? As you said, "It's not an accurate way to measure the temperature."

Get a good old fashioned mechanical grill thermometer and mount it directly to the heat sink. Here's a link to one I found to show what I'm talking about.

http://www.centralrestaurant.com/Grill-Thermometer---2-in-Dial-Stainless-Steel-c177p12987.html?st-t=google_shopping&vt-k=&vt-pti=98375234695&gclid=CLfKp_Xgj8cCFUMjgQodAZoAKA

You may want to look around for what you need. That's just the first one I found doing a search.

Take a look at the dial, it's NSF certified!  :)
Great idea Ron, yep the ir gun is not the way to go, a good ol' mechanical one should work fine. Thanks!

Offline WarpTech

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />


Elizabeth, this is very important news, as many of us have suspected that the EM Drive is NOT a closed system and that "thrust" may be explainable by what is leaking.

Looking forward to what you measure :)

How is thrust greater than a photon rocket explained by leaking photons?
Todd

Offline rfmwguy

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Note to experimentalists:

For safety, run an EM detector around the outside of your emdrive while its powered up.  Either through shoddy construction(likely) or some as yet unknown (to me) phenomenon, my resonator is leaking radiation from the small end.  Based on the fall-off as a function of distance I believe it is evanescent.  I have spectrum analyzer on order; when it arrives I'll have a better idea of what it is.

<lurk />
You can use copper adhesive tape to easy fix any leakage :)
http://www.iccfl.com/index.php?cPath=135_184&osCsid=ur8g03ipgtkkdh6src34otdh84
This is great stuff. Got my copper tape with conductive adhesive froM Mcmaster carr. Their warehouse is 15 minutes from my house...cool.

Online Rodal

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... SPR in-house software and produced the Df and resonant frequency at TE013 being:

Frustum big diameter   m: 0.2314m (my data)
Frustum small diameter: 0.1257m (my data)
Frustum centre length: 0.1386m (my data)
Mode: TE013 (my data)

Resonance: 3.9003 GHz (SPR data based on the above)
Df: 0.634 (SPR data based on the above)...
...BTW what resonance and Q do you get for my Flight Thruster estimated dimensions?...
Dimensions as defined as in this drawing

but with these numbers instead:
Frustum big diameter   : 0.2314 m (for both flat and spherical ends)
Frustum small diameter : 0.1257 m (for both flat and spherical ends)
Length perpendicular to bases : 0.1386 m (for flat ends)
Difference between spherical radii= r2 - r1: 0.1386 m  (for spherical ends)
r1 = 0.16483 m (for spherical ends)
r2 = 0.30343 m (for spherical ends)
Notice different geometries for the flat end and the spherical end case due to the different definitions of length (TheTraveller uses as "length" for the spherical end case the difference between the spherical radii)
Cone half-angle = 22.415 degrees (for spherical ends)
Cone half-angle = 20.873 degrees (for flat ends)

Mode Shape; TE013

air index of refraction at STP  = 1.000277
cVacuum = 299792458 (*meter/s*)
epsilon0 = 8.854187817*10^(-12)
mu0 = 0.999991(*copper*)*4*Pi*10^(-7)
resistivity =  1.678*10^(-8)(*copper*);

Again, this is a comparison for a cone half-angle = 22.415 degrees (for spherical ends) with a cone half-angle = 20.873 degrees (for flat ends)

                                Frequency (GHz)     Q     
Flat Ends                   3.812                    less than 72,800    (flat ends approximated by equivalent spherical sections)
Spherical Ends        3.860                    71,687                      (exact solution)

That is a difference of only 1% between TheTraveller's and Shawyer's number (3.90 GHz) and the exact solution (3.86 GHz) for spherical ends.

Q's are for a perfect geometry and based on pure copper resistivity =  1.678*10^(-8)
for other purities of copper or other materials, scale the Q by the square root of the inverse resistivity ratio

Q's for flat ends should be lower than 72,800 because of degradation losses of spherical waves on flat ends is not exactly modeled.

My prior post compared the geometries of flat ends and spherical ends having the same cone half-angle, in which case the spherical end case has lower natural frequency and higher Q. This comparison is for different geometries (different cone half-angles between the flat end and the spherical end case).

When comparing cones having the same cone half-angle: 20.873 degrees (both for flat ends and spherical ends), and the diameters previously given: big diameter   : 0.2314 m and small diameter : 0.1257 m, we have:


                                Frequency (GHz)     Q     
Flat Ends                   3.812                    less than 72,800    (flat ends approximated by equivalent spherical sections)
Spherical Ends           3.688                    74,052                      (exact solution)
« Last Edit: 08/04/2015 07:16 PM by Rodal »

Offline RotoSequence

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How is thrust greater than a photon rocket explained by leaking photons?
Todd

If I recall correctly, evanescent wave leakage doesn't involve proper/typical photons, but come from "virtual" particles instead.

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