Quote from: SeeShells on 05/21/2015 04:29 pm...Please doc this is just a simple question, but why would absolute dimensional numbers be so important as long as you're in the ballpark for resonance? I think every device I've seen has taken into account that either you mechanically tune the EM cavity or shift the insertion frequency to optimize the thrust. I've even thought of using a airtight Conductive Elastic Fabric on the endplate and varying the air pressure the chamber to optimize the reflected EM wave.Since I am skeptical of the derivation of TheTraveller's Shawye's resonance calculation (I am from Missouri: show me ) the only way I have to verify it is by comparing the mode shapes to the exact solution (which would also be useful in its own right, as per NASA and Notsosureofit). Since many mode shapes are bunched together at close frequencies, one cannot determine whether a natural frequency prediction is correct unless one assesses the mode shape prediction.I know I've been reviewing the mode work done by by Frank Davies of NASA and relating it to thrust and I'm observing some interesting correlations between the two. And it's not so much the Q. Data, more data! For instance did you sweep the frequency from ~900mhz to ~3Ghz or just dial in a close TM frequency and then fine tune? If you did sweep do you have any data you could share?
...Please doc this is just a simple question, but why would absolute dimensional numbers be so important as long as you're in the ballpark for resonance? I think every device I've seen has taken into account that either you mechanically tune the EM cavity or shift the insertion frequency to optimize the thrust. I've even thought of using a airtight Conductive Elastic Fabric on the endplate and varying the air pressure the chamber to optimize the reflected EM wave.Since I am skeptical of the derivation of TheTraveller's Shawye's resonance calculation (I am from Missouri: show me ) the only way I have to verify it is by comparing the mode shapes to the exact solution (which would also be useful in its own right, as per NASA and Notsosureofit). Since many mode shapes are bunched together at close frequencies, one cannot determine whether a natural frequency prediction is correct unless one assesses the mode shape prediction.
@TheTraveller: Excuse my obtuseness, but don't you have the design freedom to arrange for Df to be as close to unity as you like? If there's one thing that Shawyer's work teaches, it's that maximising Df maximises thrust - therefore this seems to be worthwhile.So what constraints forbid you designing for near-unity Df?
...For instance did you sweep the frequency from ~900mhz to ~3Ghz or just dial in a close TM frequency and then fine tune? If you did sweep do you have any data you could share?
Dr Rodal did this excellent bit of work, which shows near unity Dfs are possible.
We haven't heard TheTraveller's opinion.Should we change the Experimental Spreadsheet assuming that Shawyer made a typo and the DesignFactor for the Demonstrator was 0.484 instead of 0.844 ?
Quote from: SeeShells on 05/20/2015 03:49 pm...Reading it I had a question (more than one but..). And this is for everyone, why did Eagle Works observe no thrust in a EM device with no HDPE insert? Makes me wonder what effect achiral materials like this that can induce chirality would have with relativity and electromagnetic fields in your equations? Thanks nice work!Thanks a lot. The reason why a material can change the behaviour is magnetic permeability. This can enhance the effect by several magnitude orders. They use low input power, if I am right, and so this could be a good way around to such a limitation.
...Reading it I had a question (more than one but..). And this is for everyone, why did Eagle Works observe no thrust in a EM device with no HDPE insert? Makes me wonder what effect achiral materials like this that can induce chirality would have with relativity and electromagnetic fields in your equations? Thanks nice work!
Quote from: StrongGR on 05/20/2015 05:15 pmQuote from: SeeShells on 05/20/2015 03:49 pm...Reading it I had a question (more than one but..). And this is for everyone, why did Eagle Works observe no thrust in a EM device with no HDPE insert? Makes me wonder what effect achiral materials like this that can induce chirality would have with relativity and electromagnetic fields in your equations? Thanks nice work!Thanks a lot. The reason why a material can change the behaviour is magnetic permeability. This can enhance the effect by several magnitude orders. They use low input power, if I am right, and so this could be a good way around to such a limitation.High Density PolyEthylene (HDPE) is a nonconductive polymer with no special magnetic properties, its relative magnetic permeability is very nearly unity, as is generally true of polymers. Hence we cannot explain the report that NASA observed thrust with a HDPE insert and observed no thrust in a EM device without the HDPE insert based on the relative magnetic permeability of HDPE (which is practically 1).I think to explain this fact, and still be compatible with Marco's interesting paper, we must use the expression from Maxwell's theory for the speed of light:1 / c2 = μo εo = (magnetic permeabiltity) * (electric permittivity)We can use this expression to convert magnetic permeability as follows:(μo)2 = 1 / ( c4 (εo )2)if we substitute this expression in the expression for the energy density parameter we obtain:(Uo)4 / (μo)2 = (Uo)4 c4 εo 2and therefore we can eliminate the factor of c4 in Eq. 60 and get a more beautiful equation (with one less parameter) that depends explicitly on the electric permittivity as the following quantity gets transformed:(Pi2 G / ( c4 ) ) Uo)4 / c4 =(Pi2 G Uo)4 (εo)2
Quote from: TheTravellerDr Rodal did this excellent bit of work, which shows near unity Dfs are possible.I know that - and also I did the same derivations myself (upon which you commented). But that doesn't directly answer my question. You published some specs that showed you are designing to a small Df. Why?
Quote from: saucyjack on 05/21/2015 05:51 pmQuote from: Rodal on 05/21/2015 05:13 pmWe haven't heard TheTraveller's opinion.Should we change the Experimental Spreadsheet assuming that Shawyer made a typo and the DesignFactor for the Demonstrator was 0.484 instead of 0.844 ?Well, I was guessing he'd say yes, so I changed it already on http://emdrive.echothis.com/Experimental_Results. Will of course switch it back if consensus says otherwise.Could you also put also a (1) next to 0.484 and indicate in the note that Shawyer's reference has 0.844 but that this number gives a small diameter in conflict with the picture of the Demonstrator, therefore it is assumed there was typo transposition of the numbers ?
Quote from: Rodal on 05/21/2015 05:13 pmWe haven't heard TheTraveller's opinion.Should we change the Experimental Spreadsheet assuming that Shawyer made a typo and the DesignFactor for the Demonstrator was 0.484 instead of 0.844 ?Well, I was guessing he'd say yes, so I changed it already on http://emdrive.echothis.com/Experimental_Results. Will of course switch it back if consensus says otherwise.
...That's fine and depends on the kind of material used as a dielectric. I was considering teflon with mu about 10^-6 but you were using HDPE and things can be quite different...
Iulian is indeed alive and still (one assumes) possesses his eyeballs!http://www.masinaelectrica.com/emdrive-independent-test/
Quote from: Rodal on 05/21/2015 06:11 pmQuote from: StrongGR on 05/20/2015 05:15 pmQuote from: SeeShells on 05/20/2015 03:49 pm...Reading it I had a question (more than one but..). And this is for everyone, why did Eagle Works observe no thrust in a EM device with no HDPE insert? Makes me wonder what effect achiral materials like this that can induce chirality would have with relativity and electromagnetic fields in your equations? Thanks nice work!Thanks a lot. The reason why a material can change the behaviour is magnetic permeability. This can enhance the effect by several magnitude orders. They use low input power, if I am right, and so this could be a good way around to such a limitation.High Density PolyEthylene (HDPE) is a nonconductive polymer with no special magnetic properties, its relative magnetic permeability is very nearly unity, as is generally true of polymers. Hence we cannot explain the report that NASA observed thrust with a HDPE insert and observed no thrust in a EM device without the HDPE insert based on the relative magnetic permeability of HDPE (which is practically 1).I think to explain this fact, and still be compatible with Marco's interesting paper, we must use the expression from Maxwell's theory for the speed of light:1 / c2 = μo εo = (magnetic permeabiltity) * (electric permittivity)We can use this expression to convert magnetic permeability as follows:(μo)2 = 1 / ( c4 (εo )2)if we substitute this expression in the expression for the energy density parameter we obtain:(Uo)4 / (μo)2 = (Uo)4 c4 εo 2and therefore we can eliminate the factor of c4 in Eq. 60 and get a more beautiful equation (with one less parameter) that depends explicitly on the electric permittivity as the following quantity gets transformed:(Pi2 G / ( c4 ) ) Uo)4 / c4 =(Pi2 G Uo)4 (εo)2That's fine and depends on the kind of material used as a dielectric. I was considering teflon with mu about 10^-6 but you were using HDPE and things can be quite different.
We can figure out the true thrust now (T=thrust, a=air effect, in gm-wt)T + a = -0.54-T + a = +0.54/7solving by eliminating ‘a’ givesT = -0.31 gm-wtso thrusting forward at the small end
the thrust downwards is around 7 times smaller. difference on the scale is only 0.20 grams
Hi,When i saw the people start thinking i died i was concerned. I wanted to post when i have some results but now i`m forced me to post some unfinished work I just closed the cone with new setup in place and in the next days i will be busy adjusting the distance and see if i have any improvement. The work will be slow because i need to make a lot of tests with different distance for each test i need to let the magnetron to cool down for at least 5 minutes.Iulian
...(1) Magnetic susceptibilities of paramagnetic and diamagnetic materials... see anything interesting?http://www.kayelaby.npl.co.uk/general_physics/2_6/2_6_6.html