...How a builder does it is truly up to them, but they should at least consider these points. ...Shell
Quote from: SeeShells on 03/15/2016 03:27 pm...How a builder does it is truly up to them, but they should at least consider these points. ...ShellOK, but it is not up to the builder what the results of the experiment are, it is up to "Mother Nature" that rules the experimental outcome, not the builder (if the builder reports the true outcome of the experiments, of course).Therefore, experiments conducted at institutions like universities, CERN, the Cambridge Electron Accelerator (MIT and Harvard), Fermilab, etc., the experimenters do discuss (in the scientific community) and design their experiments following our knowledge of the laws of nature.If a "builder" were to design an experiment up to them" without taking into account the laws of nature, then the builder should not be surprised if their results are not accepted by others. NASA's experiments stand out as a great example (and they are the reason why many viewers at NSF look at this thread: because NASA is conducting such experiments) because they reported their experiments with much more disclosure than Shawyer but also because Paul March was actively engaged at NSF in discussing their experiments: fully provided all dimensions and materials, thoroughly answered all questions and rather than being defensive about the NASA experiment or saying that it was up to their team what they did, carefully discussed and considered all theoretical and experimental arguments from NSF contributors. That's the way to get acceptance by the scientific community.
...You bet I'd like to have a better lab table and another computer and waveguides I didn't have to build myself, but I'm limited just like the organizations you mentioned, by budget. ...
Quote from: SeeShells on 03/15/2016 04:53 pm...You bet I'd like to have a better lab table and another computer and waveguides I didn't have to build myself, but I'm limited just like the organizations you mentioned, by budget. ...I was not referring to you, you have always been positive and welcoming of comments on your build ------Concerning <<waveguides I didn't have to build myself>> and <<considering the limits of funding>>, I am involved in a project dealing with evanescent wave coupling (from a multilayer dielectric waveguide, which I plan to couple using prisms, grating is also under consideration) that may require several metal waveguides as well, most likely using TM polarization. In the range of 2 GHz (or less) these waveguides list for several thousand dollars.Do you have an actual comparison you can share of the performance of a home-built metal waveguide with the commercial waveguides? I would also appreciate any comparison you may have of thinner waveguides with the commercial waveguide constructions, or data showing that a thinner waveguide can do just as well (*) Thanks_______(*) The UberOverLord also commented on this issue, based on his experience at the US Air Force
...Thank YOU!Honestly I used a OTS rectangular aluminum stock that I had to clean up quite a bit. It received a silver electroplating on top of that. I followed this templatehttp://www.wikarekare.org/Antenna/Waveguide.html but build a better quality guide. The lucky thing was the waveguide is right in the middle of the spectrum for the guide @ 2.45GHz. I don't have any real specs to compare on the thinner walled guides vs what I built. If I had my old shop back I'd make it from heavy copper O2 free stock and bend on the industrial bender. You could contact any local shops that have the capability to bend thick copper and send it out to be electroplated with Cu and flashed over with a gold finish. That would be about 1/4 of the cost vs a commercial.Shell
Great points.Although relying on natural convection is not representative of operation in space, artificially incorporating forced convection to control the temperature is certainly an option. Superconducting EM Drive designs certainly need such forced convection cooling in order to achieve and maintain superconductivity (presently only achievable at temperatures below room temperature).
Quote from: Rodal on 03/15/2016 02:01 pmGreat points.Although relying on natural convection is not representative of operation in space, artificially incorporating forced convection to control the temperature is certainly an option. Superconducting EM Drive designs certainly need such forced convection cooling in order to achieve and maintain superconductivity (presently only achievable at temperatures below room temperature).I would like to take up this opportunity and encourage builders to embrace the new 3D manufacturing technologies and design a frustum with embedded cooling channels in the metal walls. If the coolant were running in two separate channels with counter directed coolant flow, there should be no net angular momentum at any given point in time (I think).
Quote from: dustinthewind on 03/15/2016 02:11 amQuote from: TheTraveller on 03/14/2016 11:43 pmQuote from: Flyby on 03/14/2016 11:03 pmIf the force is generated on the frustum walls (either on front/back plates or the side walls) it must come at the expense of the Q of the electromagnetic waves. Any (yet to be determined) interaction between the walls and the electromagnetic waves must come at the expense of the Q.Exactly correct. The conversion of internal cavity energy to external kinetic energy is at the expense of reduced internal cavity energy & Q as this conversions adds to cavity Q losses.No free lunches.It is all detailed in Rogers papers.I am fairly sure that a force in itself won't use up energy until the cavity actually begins to free accelerate by F.dx = Energy (if it does accelerate purely via light) . This should be similar to two mirrors accelerated away from each other and the light between them red-shifts when the mirrors actually start to accelerate. If the mirrors are held stationary and are perfectly reflective no red-shifting of the light between the mirrors should happen but a force will still be present. (While the two systems [cavity or mirrors] are different, I am assuming if there were a force purely by the pressure of light inside the cavity that we could parallel between the two systems.)On the other hand if the light is accelerating something other than the cavity as a propellant that passes through the walls then there is a chance of seeing Q or energy content drop even when the cavity isn't accelerating because the light is accelerating something else via F.dx=E . If there is some anomalous force the difference between these two scenarios might be a way to narrowing down where it is coming from. As per attached.QuoteNote that the reaction is either the acceleration a, or a force equal to Ma, but not both.EmDrive Force Measurement:http://www.emdrive.com/EmDriveForceMeasurement.pdfThe EmDrive is not a rocket. It does not generate acceleration unless it is free to move. When constrained there is no external Force generated.
Quote from: TheTraveller on 03/14/2016 11:43 pmQuote from: Flyby on 03/14/2016 11:03 pmIf the force is generated on the frustum walls (either on front/back plates or the side walls) it must come at the expense of the Q of the electromagnetic waves. Any (yet to be determined) interaction between the walls and the electromagnetic waves must come at the expense of the Q.Exactly correct. The conversion of internal cavity energy to external kinetic energy is at the expense of reduced internal cavity energy & Q as this conversions adds to cavity Q losses.No free lunches.It is all detailed in Rogers papers.I am fairly sure that a force in itself won't use up energy until the cavity actually begins to free accelerate by F.dx = Energy (if it does accelerate purely via light) . This should be similar to two mirrors accelerated away from each other and the light between them red-shifts when the mirrors actually start to accelerate. If the mirrors are held stationary and are perfectly reflective no red-shifting of the light between the mirrors should happen but a force will still be present. (While the two systems [cavity or mirrors] are different, I am assuming if there were a force purely by the pressure of light inside the cavity that we could parallel between the two systems.)On the other hand if the light is accelerating something other than the cavity as a propellant that passes through the walls then there is a chance of seeing Q or energy content drop even when the cavity isn't accelerating because the light is accelerating something else via F.dx=E . If there is some anomalous force the difference between these two scenarios might be a way to narrowing down where it is coming from.
Quote from: Flyby on 03/14/2016 11:03 pmIf the force is generated on the frustum walls (either on front/back plates or the side walls) it must come at the expense of the Q of the electromagnetic waves. Any (yet to be determined) interaction between the walls and the electromagnetic waves must come at the expense of the Q.Exactly correct. The conversion of internal cavity energy to external kinetic energy is at the expense of reduced internal cavity energy & Q as this conversions adds to cavity Q losses.No free lunches.It is all detailed in Rogers papers.
If the force is generated on the frustum walls (either on front/back plates or the side walls) it must come at the expense of the Q of the electromagnetic waves. Any (yet to be determined) interaction between the walls and the electromagnetic waves must come at the expense of the Q.
Note that the reaction is either the acceleration a, or a force equal to Ma, but not both.
EM propulsion study for USAF written in 1989 contains a lot about some of the theories and speculations similar to emdrive. 169 pages...5 D math...I suspect theory people will find this old paper interesting:https://drive.google.com/file/d/0B4Ez9NDUxpYLZThJTy15TUdPVnM/view
Forgive me if this has been posted already, but there appears to be a new Emdrive paper. Any thoughts? http://www.helsinki.fi/~aannila/arto/emdrive.pdfThe paper is written by Arto Annila, a Professor in Physics at the University of Helsinki, Erkki Kolehmainen, a Professor of Chemistry at the University of Jyväskylä and Patrick Grahn, an engineer with a specialization in COSMOL Multiphysics at the University of Helsinki.The abstract to the paper notes:" Recent reports about propulsion without reaction mass have been met with disbelief. Closed metal cavities, when fueled with microwaves, have delivered thrust without any apparent exhaust. Thus the Law of Action-Reaction seems to have been violated. We consider the possibility that the exhaust is in a form that has so far escaped both experimental detection and theoretical attention. In the thruster’s cavity microwaves interfere with each other and invariably some photons will also end up co-propagating with opposite phases. At the destructive interference electromagnetic fields cancel. However, the photons themselves do not vanish for nothing but continue in propagation. These photon pairs without net electromagnetic field do not reflect back from the metal walls but escape from the resonator. By this action momentum is lost from the cavity which, according to the conservation of momentum, gives rise to an equal and opposite reaction. We examine theoretical corollaries and practical concerns that follow from the paired –photon conclusion."
Quote from: CW on 03/15/2016 07:05 pmQuote from: Rodal on 03/15/2016 02:01 pmGreat points.Although relying on natural convection is not representative of operation in space, artificially incorporating forced convection to control the temperature is certainly an option. Superconducting EM Drive designs certainly need such forced convection cooling in order to achieve and maintain superconductivity (presently only achievable at temperatures below room temperature).I would like to take up this opportunity and encourage builders to embrace the new 3D manufacturing technologies and design a frustum with embedded cooling channels in the metal walls. If the coolant were running in two separate channels with counter directed coolant flow, there should be no net angular momentum at any given point in time (I think).I am quite willing to do the CAD work necessary for this, provided someone can provide me with the dimensions and further desires. Exactly what adjustments I might need to make to account for production method are dependent on how they want the device made.One thing I was considering actually was the possibility of designing a sort of "jacket" that others could place their frustum in (slather the outside in some sort of thermal compound) and use to help cool it.
Thank you for this interesting paper, which I'm sure has never been discussed at NSF EM Drive thread previously.
Quote from: Rodal on 03/16/2016 01:24 amThank you for this interesting paper, which I'm sure has never been discussed at NSF EM Drive thread previously.The authors seem to be claiming that because of destructive interference at the frustum-wall interface, photons are exiting the apparatus. My understanding is that when there is destructive interference, photons are directed back to the source.
Quote from: rfmwguy on 03/15/2016 02:32 amEM propulsion study for USAF written in 1989 contains a lot about some of the theories and speculations similar to emdrive. 169 pages...5 D math...I suspect theory people will find this old paper interesting:https://drive.google.com/file/d/0B4Ez9NDUxpYLZThJTy15TUdPVnM/viewrfmwguy - thanks!! A breath of fresh air. Helps the thesis that I'm not mad to find one other person who thinks that we should be investigating the coupling between EM and gravitational fields. Or maybe just a cellmate...Section 2.10 looks interesting, esp equation 271. Made me wonder whether FEKO could map E.Edot and E.CurlB across the frustrum.I think equation 168 may speak to CW's thought on the variation of the rate of flow of time.Interesting the remarks around equation 221!R.