PS: I understand he says he used the NASA Eagleworks dimensions, if that is the case, the resonant frequency at near 2.45 GHz should be TM212 (transverse magnetic, same mode excited by Iulian Berca), instead of TE212 (transverse electric)
Quote from: Rodal on 08/11/2015 12:38 pmPS: I understand he says he used the NASA Eagleworks dimensions, if that is the case, the resonant frequency at near 2.45 GHz should be TM212 (transverse magnetic, same mode excited by Iulian Berca), instead of TE212 (transverse electric)As calculated.
Quote from: TheTraveller on 08/11/2015 01:12 pmQuote from: Rodal on 08/11/2015 12:38 pmPS: I understand he says he used the NASA Eagleworks dimensions, if that is the case, the resonant frequency at near 2.45 GHz should be TM212 (transverse magnetic, same mode excited by Iulian Berca), instead of TE212 (transverse electric)As calculated.As calculated by NASA: 2.45 GHz TM212 (transverse MAGNETIC mode) (not TE212) for NASA's truncated cone dimensions (no dielectric insert)My exact solution agrees with NASA
As calculated by NASA: 2.45 GHz TM212 (transverse MAGNETIC mode) (not TE212) for NASA's truncated cone dimensions (no dielectric insert)My exact solution agrees with NASAFull NASA report attached below
Quote from: deltaMass on 08/11/2015 01:25 pmI'm still confused. Are we looking at a single impulsive event, or a steady-state force?The unraveling of the EM Drive "force measurement" this is what is great about replications. The South African experiment does not show a constant steady-state force.
I'm still confused. Are we looking at a single impulsive event, or a steady-state force?
Quote from: Rodal on 08/11/2015 01:28 pmQuote from: deltaMass on 08/11/2015 01:25 pmI'm still confused. Are we looking at a single impulsive event, or a steady-state force?The unraveling of the EM Drive "force measurement" this is what is great about replications. The South African experiment does not show a constant steady-state force.His fulcrum is undamped and will oscillate for some time before settling at the final value. You know that so why the comment?
Quote from: Rodal on 08/11/2015 01:20 pmQuote from: TheTraveller on 08/11/2015 01:12 pmQuote from: Rodal on 08/11/2015 12:38 pmPS: I understand he says he used the NASA Eagleworks dimensions, if that is the case, the resonant frequency at near 2.45 GHz should be TM212 (transverse magnetic, same mode excited by Iulian Berca), instead of TE212 (transverse electric)As calculated.As calculated by NASA: 2.45 GHz TM212 (transverse MAGNETIC mode) (not TE212) for NASA's truncated cone dimensions (no dielectric insert)My exact solution agrees with NASAAs calculated by NASA: 1.88 GHz TE212 (transverse ELECTRIC mode occurs at a much lower frequency than 2.45 GHz) for NASA's truncated cone dimensions (no dielectric insert)My exact solution agrees with NASA
There is always some amount of damping in any set-up (if there would be no damping we would be able to have perpetual motion machines, which is impossible). But fair enough, since I have not had a chance to do detailed modeling of his set-up (I don't even know his dimensions) I withdraw my comments until I have the chance to model his set-up.Can you provide a link to his cone dimensions, masses, displacement/force measuring device, etc., for me to model his experiment?
...Proof of frustum resonance in any mode is measured Force generation. No Force generation, means the mode and resonance calc is not correct. What NASA needs to show is the S11 return loss scans for those frequencies. When you see the return loss dB dips, then you know there is a resonant mode. Need a different antenna to properly excite TE and TM modes.EW's internal frustum length only needs to be 3mm longer than SA Paul's frustum length for the 2.445GHz resonance to turn into a 2.422GHz resonance. Thus I suggest the attached does show a TE212 resonance that EW found, Paul in SA found and my spreadsheet predicts.
Calculation of resonant frequencies in cavities is well-known and established. Has been replicated routinely in thousands of carefully designed experiments. Routinely done at CERN and other particle accelerators using Finite Element Analysis . The hundreds of thousands of readers of this thread can conduct their own calculations based on the NASA dimensions (see attached NASA report for dimensions frequencies and mode shape) and independently verify whether the mode shape at 2.45 GHz is TM212 or TE212
Quote from: TheTraveller on 08/11/2015 01:44 pm...Proof of frustum resonance in any mode is measured Force generation. No Force generation, means the mode and resonance calc is not correct. What NASA needs to show is the S11 return loss scans for those frequencies. When you see the return loss dB dips, then you know there is a resonant mode. Need a different antenna to properly excite TE and TM modes.EW's internal frustum length only needs to be 3mm longer than SA Paul's frustum length for the 2.445GHz resonance to turn into a 2.422GHz resonance. Thus I suggest the attached does show a TE212 resonance that EW found, Paul in SA found and my spreadsheet predicts.Therefore according to you CERN, MIT, CalTech, Princeton, etc., and anybody that calculates frequencies and mode shapes of resonant cavities using Finite Element analysis and exact solutions are getting wrong results and they should immediately switch to using your Excel spreadsheet to calculate resonant frequencies and mode shapes?
Quote from: Rodal on 08/11/2015 01:38 pmThere is always some amount of damping in any set-up (if there would be no damping we would be able to have perpetual motion machines, which is impossible). But fair enough, since I have not had a chance to do detailed modeling of his set-up (I don't even know his dimensions) I withdraw my comments until I have the chance to model his set-up.Can you provide a link to his cone dimensions, masses, displacement/force measuring device, etc., for me to model his experiment?https://www.reddit.com/r/EmDrive/comments/3gkwcz/build_complete_initial_testing_done_emdrive_build/
A knife-edge fulcrum is composed of a long balancing beam which rests on two razor edges. This allows for very sensitive measurement of minuscule forces such as those produced by an EMDrive.One issue that could become a problem is air currents which could potentially give false positives. Once the frustum is set up on the fulcrum with a counterweight the fulcrum will be left for 10 minutes in the testing room. The setup will then be powered on for a burst of 10 seconds.The frustum will be suspended in an upright position below the beam of the fulcrum. A laser will be attached to the other end of the beam which will project onto graph paper. This setup will detect any upwards or downwards forces on the frustum. A camera is positioned perpendicular to the graph paper to make measurements of the laser point.
Quote from: Rodal on 08/11/2015 01:33 pmCalculation of resonant frequencies in cavities is well-known and established. Has been replicated routinely in thousands of carefully designed experiments. Routinely done at CERN and other particle accelerators using Finite Element Analysis . The hundreds of thousands of readers of this thread can conduct their own calculations based on the NASA dimensions (see attached NASA report for dimensions frequencies and mode shape) and independently verify whether the mode shape at 2.45 GHz is TM212 or TE212As I said proof of the calc is seeing a S11 return loss dip at the calculated freq. Is easy to do. EW has the VNA to do the scan. So why no scans to back the calcs?
My limited experience with the comsol EM module is it works fine! Without calculations it is difficult(not possible) to say a specific peak in the S-parameter plot is the target resonance.
I see the dimensions of the truncated cone there but I don't see enough details to do any modeling: no masses and most bothersome, no dimensions or description of the testing set-up except:
Quote from: Rodal on 08/11/2015 02:00 pmI see the dimensions of the truncated cone there but I don't see enough details to do any modeling: no masses and most bothersome, no dimensions or description of the testing set-up except:This info is in his report. How is this not enough info to do an analysis?Hypothesis Test 1 – NASA cavity size at 2450MHzWhen microwaves are supplied into the cavity, a thrust will be produced by the frustum.Hypothesis Test 2 – Frustum extended by 50 mm excited at 2450MHzWhen microwaves are supplied into the cavity, a greater thrust will be produced by the increase in resonance.The specifications of the frustum are as follows Height (perpendicular): 228 mm (1) 278mm (2)Big Diameter: 279.4mmSmall Diameter: 158.8mmMaterial: CopperAntenna location: 34.29 mm from Big Diameter
I see the dimensions of the truncated cone there but I don't see enough details to do any modeling: no masses and most bothersome, no dimensions or description of the testing set-up except
Do you understand how to model the dynamic oscillations in a testing set-up ?
Quote from: Rodal on 08/11/2015 02:24 pmDo you understand how to model the dynamic oscillations in a testing set-up ?1st you need to confirm resonance. Last time that I remember you commented there was no resonance for the EW copper frustum at 2.45GHz. Might try that again and over the range +-30MHz.
there was no resonance for the EW copper frustum at 2.45GHz