@ RODALDid you say you had an exact analytic solution for the truncated cavity ?
@ RODALCan you put it in terms of a dispersion relation that can be evaluated at the ends ?
@ RODALThat should keep you busy ! (but worth it)
@ RODALDo you have the dielectric constants (@ freq) and the dimensions ?
...Best, Paul M.
Just want to put this out there in case it helps. During all the research of literature concerning QV momentum, these two materials came up again and again. Cr2O3 and FeGaO3. Or if that is too high speed, PTFE or PVDF. To get over the 100uN hump, it might be time to dump the PE and try something else.
Quote from: Star-Drive on 02/08/2015 07:00 pm...Best, Paul M.Paul : did NASA (or an outside lab) measure with a dielectrometer the dielectric constant and the tan delta of the High Density PE you used for the dielectric ?Otherwise, do you have the relative electrical permittivity and the tan delta of the HD PE at a frequency of ~ 2 GHz at the temperatures experienced during the experiment, from some other source ?If not, do you have the molecular weight of the HD PE used for the dielectric or some form of further characterization from the dielectric supplier ?Thanks
Quote from: Mulletron on 02/09/2015 01:24 amJust want to put this out there in case it helps. During all the research of literature concerning QV momentum, these two materials came up again and again. Cr2O3 and FeGaO3. Or if that is too high speed, PTFE or PVDF. To get over the 100uN hump, it might be time to dump the PE and try something else.Or if that doesn't work...Why should there be a target to achieve a given thrust with a single EMDrive?Why not just achieve the required thrust at Glenn by using n drives to add up to the required thrust?For 100uN one needs two EM Drives each providing 50uN, or three EM Drives each providing 33uN and so on
So... I haven't really done a good long read of this thread in a huge amount of time, since before thread 1 reached a few pages long, even. Would it be possible for someone to produce a 1-2 paragraph summary of what's been going on here over the past few months? Are we... building our own EmDrive, now?
1) We are exploring the validity of the claims of the different experimenters (NASA in the USA, Shawyer in the UK and Juan Yang in China) by systematically analyzing their experiments.2) Some of the people in this forum are also designing and working to make their own prototypes and experiments.3) One of the people in this forum (@NotSoSureOfIt), has made an outstanding contribution by independently deriving an equation that is not far from the claimed experimental results.4) There are a number of possible physical reasons for the experimental results to be valid for space propulsion as well as for the results to be an experimental artifact that may not produce any propulsion in space.5) There have been no further reports from NASA on the experiments that were supposed to be replicated at their other centers (JPL and Glenn) or at John Hopkins University. Actually @wembley, who is an aerospace technology reporter, reports that it is his opinion that NASA has a "news blackout" on this matter, and China's Juan Yang is not saying much either. The Chinese seem to be much further along than NASA, as they reported much greater thrust and they have conducted more thorough experiments (including being the first to numerically report the effects of temperature and temperature gradients with thermocouples embedded in the metal). Shawyer in the UK seems to be much further ahead than NASA as he claims he is exploring a superconducting design. Shawyer (UK) made a presentation in Canada late last year where he showed his latest design (using superconductivity) which he claims will result in much greater thrust/PowerInput (see image below).
Is copper the ideal material for the frustum? Or are there even better materials, theoretically?
Quote from: sanman on 02/09/2015 05:27 amIs copper the ideal material for the frustum? Or are there even better materials, theoretically?I think maybe it was Mulletron that previously pointed out this paper:https://hal.archives-ouvertes.fr/hal-01074608/documentThe conjecture in that paper is that building the larger diameter plate (R1) out of metglas 2714A, a significant amplification of the effect would result. Perhaps there is a courageous person or group with some funds to put this to the test. It would be interesting to see an experiment with the partial metglas construction to rule the theory in or out.Given that metglas 2714A is a room-temperature material, it would be considerably easier to achieve an amplification that way than lining the interior of the test article with superconducting film and cooling to liquid nitrogen temperatures.