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.

The copper frustum we built and now are using has the following internal copper surface dimensions.Large OD : 11.00 " (0.2794m)Small OD: 6.25" (0.1588 m) & Length : 9.00 " (0.2286m)

Bottom diam.: 11.01 inch (279.7 mm)Top diam.: 6.25 inch (0.1588 mm)Height: 9.00 inch (228.6 mm)Material: 101 Copper Alloy

....Rodal posted this back a few pages. It may or may not relate to other frustums and would probably depend on material thickness ect. It is the researchgate link. http://forum.nasaspaceflight.com/index.php?topic=39004.msg1468340#msg1468340 I think it mentioned time to buckle if I remember correctly. Edit: I don't think much long term thrust could be had from this after thermal equilibrium is reached. The force should decrease with time as the thermal expansion decelerates. It might be helpful to know the time to thermal equilibrium.Edit2: Also, any positive thrust signal observed due to thermal expansion should be an equal and opposite signal upon powering down. Thermal contraction would give a negative thrust.

Is it possible to evaluate these experimental device's sensitivities to deviations from the calculated optimum resonance frequency at this time?

...

Quote from: Rodal on 01/05/2016 12:37 pm...Thanks for clarifying that you addressed separately the buckling and expansion. I apologize as I may have not made that clear in my statement. I was away a day so wasn't able to respond immediately. I take it that buckling is a one time thing right? So if it occurs once it shouldn't occur again once the deformation is permanent? If so than yeah, I guess that would give a single impulse without a retraction event. You mentioned the artifact thrust from NASA is partly due to thermal expansion or displacement of mass center? Did they also observe the retraction of that center of mass when they shut down the power? I have to think back to those plots and I vaguely think that maybe there was a retraction event, but I will have to go back and look. I was thinking that if we knew the time to thermal equilibrium, would it be advisable to at least keep the frustum powered on for a time longer than that so that we are observing more than just those events?Edit: well to compound the problem in most cases the frustum is in air so there is the convection problem included with long term tests.Edit2: one thing that worries me is putting the frustum in an insulated box (closed system) might eliminate thermal equilibrium (continuous heating) unless maybe an internal heat sink could reduce that to some extent.

for NASA's experiment without a dielectric we can say that the exact solution says that there was indeed a natural frequency for mode TE012 within 0.1% of the measured frequency, but as to whether the measured frequency was at the resonant peak, one has to rely on NASA's team having actually found peak resonance with S21 and S11 measurements (because we don't know the dimensions of NASA's resonant cavity to the precision required to calculate the resonant peak with all the required digits of numerical precision).

EXPERIMENTAL PROOF THAT NASA'S TEST WITHOUT A DIELECTRIC INSERT WAS IN RESONANCE AT THE FREQUENCY REPORTED IN NASA'S REPORTSince we had concluded in http://forum.nasaspaceflight.com/index.php?topic=39214.msg1470613#msg1470613that:Quote for NASA's experiment without a dielectric we can say that the exact solution says that there was indeed a natural frequency for mode TE012 within 0.1% of the measured frequency, but as to whether the measured frequency was at the resonant peak, one has to rely on NASA's team having actually found peak resonance with S21 and S11 measurements (because we don't know the dimensions of NASA's resonant cavity to the precision required to calculate the resonant peak with all the required digits of numerical precision). Finally, we reproduce again the experimental data from NASA Johnson Eagleworks Laboratory that proves that their experiment without dielectric inserts in their frustum of a cone cavity was indeed in resonance.The resonance for mode shape TE012 without dielectric inserts was measured with an Agilent Model 9923A, 4.0 GHz Field Fox Vector Network Analyzer (VNA) both in the S11 and S21 modes (as shown in the pictures below) using the frustum RF loop antenna as input and the frustum sense antenna located 180 degrees around from the loop antenna with both antennas being at the same 15% of the height from the large end of the frustum, i.e., 0.15 * 9.00” = 1.35” or 34.29mm away from the large end. The TE012 resonant frequency without the dielectric PE disc inserts was measured at 2.167137 GHz using either the S11 or S21 methods as shown by the two attached VNA slides. Thus, any claims made about this test without dielectric inserts in NASA's frustum of a cone cavity with mode shape TE012 at 2.167 GHz not being in resonance are shown to be completely baseless, false and misleading.This, factual information shows without a doubt that indeed NASA's frustum of a cone without dielectric inserts was in resonance with mode shape TE012 at 2.167 GHz in agreement with NASA's report and in agreement with the COMSOL Finite Element Analysis calculation and in agreement with the exact solution I calculated using Wolfram Mathematica.

Quote from: Rodal on 01/11/2016 07:28 pmEXPERIMENTAL PROOF THAT NASA'S TEST WITHOUT A DIELECTRIC INSERT WAS IN RESONANCE AT THE FREQUENCY REPORTED IN NASA'S REPORTSince we had concluded in http://forum.nasaspaceflight.com/index.php?topic=39214.msg1470613#msg1470613that:Quote for NASA's experiment without a dielectric we can say that the exact solution says that there was indeed a natural frequency for mode TE012 within 0.1% of the measured frequency, but as to whether the measured frequency was at the resonant peak, one has to rely on NASA's team having actually found peak resonance with S21 and S11 measurements (because we don't know the dimensions of NASA's resonant cavity to the precision required to calculate the resonant peak with all the required digits of numerical precision). Finally, we reproduce again the experimental data from NASA Johnson Eagleworks Laboratory that proves that their experiment without dielectric inserts in their frustum of a cone cavity was indeed in resonance.The resonance for mode shape TE012 without dielectric inserts was measured with an Agilent Model 9923A, 4.0 GHz Field Fox Vector Network Analyzer (VNA) both in the S11 and S21 modes (as shown in the pictures below) using the frustum RF loop antenna as input and the frustum sense antenna located 180 degrees around from the loop antenna with both antennas being at the same 15% of the height from the large end of the frustum, i.e., 0.15 * 9.00” = 1.35” or 34.29mm away from the large end. The TE012 resonant frequency without the dielectric PE disc inserts was measured at 2.167137 GHz using either the S11 or S21 methods as shown by the two attached VNA slides. Thus, any claims made about this test without dielectric inserts in NASA's frustum of a cone cavity with mode shape TE012 at 2.167 GHz not being in resonance are shown to be completely baseless, false and misleading.This, factual information shows without a doubt that indeed NASA's frustum of a cone without dielectric inserts was in resonance with mode shape TE012 at 2.167 GHz in agreement with NASA's report and in agreement with the COMSOL Finite Element Analysis calculation and in agreement with the exact solution I calculated using Wolfram Mathematica.Based on this measurement data I've got a look to my calculated frequency for this case and find:Mode calculated(GHz) Comsol(GHz) diff Comsol(%) diff Comsol(GHz) measured NASA(GHz) diff measured(%)TE012 2,1653438127 2,1794 -0,64 -0,014 2,167138 -0,08279Maybe its based on tiny differences between the final real measured cavity and the Comsol simulation.Of course there are much larger differences for many of the other modes in my spreadsheet*. As I wrote elsewhere I believe more in field simulations because it works.* I use it only for general overview.

QUALITY OF RESONANCE "Q" FOR NASA'S TEST WITHOUT A DIELECTRIC INSERTFinally, what was the predicted Quality of Resonance ("Q") for NASA's test without a dielectric insert?Using the following resistivity for the copper alloy used for this test:Material: Copper alloy 101resistivity = 1.71*10^(-8) ohm meterSources for this material value: http://www.azom.com/article.aspx?ArticleID=2850#_Physical_Properties_of http://www.husseycopper.com/production/alloys/electrical/c-101-00/Using the following geometrical dimensions for the frustum of a cone, as used by Frank Davis:bigDiameter = (11.01 inch)*(2.54 cm/inch)*(1 m/(100 cm)); smallDiameter = (6.25 inch)*(2.54 cm/inch)*(1 m/(100 cm)); axialLength = (9 inch)*(2.54 cm/inch)*(1 m/(100 cm)); the exact solution, using Wolfram Mathematica to solve Maxwell's equations, gives:Q = 78642So, a very good Q value is predicted for mode shape TE012 at the frequency:measured frequency at which NASA test was performed: 2.168 GHzcalculated natural frequency (exact solution, Dr. Rodal using Wolfram Mathematica): 2.165 GHzfor NASA's test without a dielectric insert that resulted in no thrust.The fact that this NASA test resulted in zero "anomalous force", and that Paul March at NASA had the great insight to introduce dielectric inserts at the small end to produce the anomalous force, is one of the most important data point in the history of EM Drive experiments

...These are great news. I came to nearly the same conclusion some time last year(Q=79011). I never post it, at least I am not sure about the formula (found an approximation in an cern paper about cavities if my memory is correct) and my implementation. No -3dB bandwidth needed for the calculation, its mode,volume, conductivity dependent.Based on this the Q at larger volumes is in general (mode dependent) bigger than for smaller volume. I think more energy can be stored in larger volumes.If I try to use to divide all dimensions by a factor of 10, I get a 10 times higher resonant frequency (good so far) but a Q of only 24985. Could you so kind to check this please, I can feel something may still wrong with this calculation although the number for the original dimensions fits yours very well.

Quote from: X_RaY on 01/12/2016 09:19 pm...These are great news. I came to nearly the same conclusion some time last year(Q=79011). I never post it, at least I am not sure about the formula (found an approximation in an cern paper about cavities if my memory is correct) and my implementation. No -3dB bandwidth needed for the calculation, its mode,volume, conductivity dependent.Based on this the Q at larger volumes is in general (mode dependent) bigger than for smaller volume. I think more energy can be stored in larger volumes.If I try to use to divide all dimensions by a factor of 10, I get a 10 times higher resonant frequency (good so far) but a Q of only 24985. Could you so kind to check this please, I can feel something may still wrong with this calculation although the number for the original dimensions fits yours very well.You are correct on all counts I will be posting further...