Don't understand this end plate spacing protocol. First you say it's a user input. Then the user chooses a mode (say TE01) and then is supposed to "use" a specific value of end plate spacing. So which is it? manual input or autocalculated?

I think you could automate that, but no matter. If I give Solver the two diameters and a rough endplate spacing, and a frequency, then given fixed P,Q, I need max Df in order to get max thrust. Have you tried that?In other words, find Df|max = f(Dbig, Dsmall, f, L)All we care about is maximising the thrust.

Quote from: davish on 05/30/2015 08:50 pmQuote from: Rodal on 05/30/2015 08:36 pmOh Baby, here is a test stand floating on air, ready for baby EM drive ...Is this "baby" EM Drive supposed to have lower thrust according to any of the theories? Or is thrust completely based on resonance?Some theories have thrust inversely proportional to frequency (hence this one at 24 GHz should have ~10 times less thrust than the ones at 2.4 GHz so far tested, based on inverse of linear proportionality alone)McCulloch's formula F = PQl/c * (1/w_small - 1/w_big) where l is the cavity length is independent of frequency. But it is still proportional to power input.Most theories have thrust proportional to PowerInput This just has a little battery, so also have to factor out less thrust due to the lower Power Input So, yes, substantially less thrust, according to those theories.Higher frequency also means more geometrical attenuation, perhaps that's good, if it also has higher Q to go with itAnd you can put a lot of these ones together, and it looks much neater and Hi-Tech If it works, it can go right away into a CubeSat

Quote from: Rodal on 05/30/2015 08:36 pmOh Baby, here is a test stand floating on air, ready for baby EM drive ...Is this "baby" EM Drive supposed to have lower thrust according to any of the theories? Or is thrust completely based on resonance?

Oh Baby, here is a test stand floating on air, ready for baby EM drive ...

We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust

It looks instead that you have made an error somewhere, as the natural frequency for mode TE012 without a dielectric insert is substantially lower:

Early on EW did test their frustum without a dielectric and made the following comments:http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdfQuoteWe performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrustUsing their published cavity dimensions, TE012 mode at 2.168GHz as input to the EM Drive design calculator, it is clear why they didn't see any thrust. The small end was deeply in cutoff as per the attached EWTest2.If they had used 2,315,240,095Hz (calculated using Goal Seek), they would have achieved cavity resonance in TE012 mode and assuming a frustum Q of 20,000 measured around 3.2mN of thrust for their 30W of input power. As attached EWTest3.Maybe all that EW need to do to see significant thrust is to revisit their 1st test (no dielectric) and excite it at 2,315,240,095Hz using an appropriate antenna and antenna placement?

Quote from: TheTraveller on 05/31/2015 03:38 pmEarly on EW did test their frustum without a dielectric and made the following comments:http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdfQuoteWe performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrustUsing their published cavity dimensions, TE012 mode at 2.168GHz as input to the EM Drive design calculator, it is clear why they didn't see any thrust. The small end was deeply in cutoff as per the attached EWTest2.If they had used 2,315,240,095Hz (calculated using Goal Seek), they would have achieved cavity resonance in TE012 mode and assuming a frustum Q of 20,000 measured around 3.2mN of thrust for their 30W of input power. As attached EWTest3.Maybe all that EW need to do to see significant thrust is to revisit their 1st test (no dielectric) and excite it at 2,315,240,095Hz using an appropriate antenna and antenna placement?That doesn't seem to add up. I think the lack of thrust was due to the antioxidation coating. http://forum.nasaspaceflight.com/index.php?topic=36313.msg1361900#msg1361900

Quote from: TheTraveller on 05/31/2015 03:58 pmQuote from: Rodal on 05/31/2015 03:52 pmIt looks instead that you have made an error somewhere, as the natural frequency for mode TE012 without a dielectric insert is substantially lower:The guide wavelength was way below small end cutoff. Not my equations. Standard microwave stuff. This is based on the standard Shawyer Df equation. Run the numbers, using the Shawyer Df equation yourself.Exactly, you are using approximations that are not as good as COMSOL Finite Element Analysis or an exact solution in terms of Legendre Associated functions and spherical Bessel functions. Those handbook formula approximations used in the spreadsheet cannot be relied to make statements to such a degree of precision.The Finite Element solution and the exact solution do not use that formula you are using for cut-off wavelength. The FEA and the exact solution automatically cut-off modes based on the eigenvalue problem solution. No side conditions with approximate formulas.

Quote from: Rodal on 05/31/2015 03:52 pmIt looks instead that you have made an error somewhere, as the natural frequency for mode TE012 without a dielectric insert is substantially lower:The guide wavelength was way below small end cutoff. Not my equations. Standard microwave stuff. This is based on the standard Shawyer Df equation. Run the numbers, using the Shawyer Df equation yourself.

Okay, seriously can we get past this back and forth arguing between the traveler and rodal. Its giving me a headache and its deluding the conversation for us all.

I think it is important for all to remember that the EM drive is a physical system, not a mathematical one. In the physical system, cutoff is not a line in the sand that you shall not cross, rather it is (probably) the center of a range where propagation drops below some relative value of db. The EM drive will do as it does over a range of frequencies, plus or minus, just some will do better than others.

Yes and as much of early thread 2 will attest, using methods for calculating cylinders will get you close to frustums but no cigar. Also the accuracy of Eagleworks Comsol simulations has been proven accurate using physical measurement (thermal camera for example).