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#1380 by SeeShells on 18 Apr, 2016 16:01
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As previously remarked in my posts, the concerns about HDPE "being able to handle the heat" expressed by another person (not you) may be completely misguided, the HDPE is being used as a dielectric insert for electromagnetic purposes. It is not used as a screw to hold something in place:
...3. Would a silicone based polymer be better as a dielectric as it would be better able to handle the heat.
1) arising from people incorrectly confusing the glass transition temperature (Tg) with the melting temperature (Tm)
2) the temperature dependence of HDPE may actually be the reason why there is a special effect occurring, as both the real and imaginary parts of the complex permittivity are strong functions of temperature and frequency near the Tg. This affects the index of refraction, it therefore affects the group velocity.
3) it is incongrous to be concerned about dielectrics exceeding the Tg solely on the basis of the material stiffness decreasing with temperature. For example, most rubber materials are above their Tg at ambient temperature (that is one way to define rubbery properties: for the temperature to be above the Tg). Does that mean that one cannot use a rubber material (like silicone rubber, which has a Tg below room temperature, but a high melting point Tm) as a dielectric according to this people ?
The purpose of a dielectric in a resonant electromagnetic cavity like the EM Drive is not for structural reasons, the purpose is not to have a particular stiffness, the purpose of a dielectric is due to its electromagnetic properties.
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
Shell -
#1381 by Rodal on 18 Apr, 2016 16:12
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...
Yes
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
Shell
1) It was described as "melting". But the photographs did not show melting: the screws did not turn into a viscous liquid, as it happens when the melting temperature is exceeded.
Instead, what may have happened was that the Tg was exceeded, thus the screws became rubbery, the heat deflection temperature was exceeded and viscoelastic-plastic material behavior took place. The "melting" description was a non-technical non-material-science description used in a forum to describe the rubbery behavior of the screws.
2) In any case, a screw has a structural purpose: it has to support a given stress, and thus it is preferable for a screw to be made of a stiff elastic material. That is why screws are usually not made of rubber.
3) The dielectric in a resonant cavity like the EM Drive is not used for any structural purpose, The dielectric is not used as a screw. It is misguided to think so. The dielectric in an electromagnetic resonant cavity like the EM Drive is there for its electromagnetic properties, and not for structural purposes.
4) That is why rubbery materials like silicone rubber, Neoprene etc. are routinely used as dielectrics: they are above Tg at room temperature.
5) The interesting behavior observed by NASA for HDPE dielectric may be due to the its properties near Tg, at operating temperature. It would be misguided to insist on a dielectric chosen for its structural properties rather than its electromagnetic purposes for providing thrust (including nonlinear behavior of complex permittivity and piezoelectric properties).
6) What has been written about group velocity in these threads, is incorrect, regarding HDPE near Tg. What was written about group velocity was from people assuming that the electric permittivty was a constant. They did not consider its temperature dependence near Tg. -
#1382 by SeeShells on 18 Apr, 2016 16:23
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https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335583#msg1335583...
Yes
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
Shell
1) It was described as "melting". But the photographs did not show melting: the screws did not turn into a viscous liquid, as it happens when the melting temperature was exceeded. Instead, what happened was that the Tg was exceeded, thus the screws became rubbery, the heat deflection temperature was exceeded and viscoelastic-plastic material behavior took place. The "melting" description was a non-technical non-material-science description used in a forum to describe the rubbery behavior of the screws.
2) A screw has a structural purpose: it has to support a given stress, and thus it is preferable for a screw to be made of a stiff elastic material. That is why screws are usually not made of rubber.
3) The dielectric in a resonant cavity like the EM Drive is not used for any structural purpose, The dielectric is not used as screw. It is misguided to think so. The dielectric in an electromagnetic resonant cavity like the EM Drive is there for its electromagnetic properties, and not for structural purposes.
4) That is why rubbery materials like silicone rubber, Neoprene etc. are routinely used as dielectrics: they are above Tg at room temperature.
5) The interesting behavior observed by NASA for HDPE dielectric may be due to the its properties near Tg, at operating temperature. It would be misguided to insist on a dielectric chosen for its structural properties rather than its electromagnetic purposes for providing thrust (including nonlinear behavior of complex permittivity and piezoelectric properties).
6) What has been written about group velocity in these threads, is incorrect, regarding HDPE near Tg. What was written about group velocity was from people assuming that the electric permittivty was a constant. They did not consider its temperature dependence.
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#1383 by Rodal on 18 Apr, 2016 16:33
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If a polymer exceeds it melting point, it will not be in its previous shape anymore but it will be in a puddle of liquid, due to gravity.
https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335583#msg1335583...
Yes
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
Shell
1) It was described as "melting". But the photographs did not show melting: the screws did not turn into a viscous liquid, as it happens when the melting temperature was exceeded. Instead, what happened was that the Tg was exceeded, thus the screws became rubbery, the heat deflection temperature was exceeded and viscoelastic-plastic material behavior took place. The "melting" description was a non-technical non-material-science description used in a forum to describe the rubbery behavior of the screws.
2) A screw has a structural purpose: it has to support a given stress, and thus it is preferable for a screw to be made of a stiff elastic material. That is why screws are usually not made of rubber.
3) The dielectric in a resonant cavity like the EM Drive is not used for any structural purpose, The dielectric is not used as screw. It is misguided to think so. The dielectric in an electromagnetic resonant cavity like the EM Drive is there for its electromagnetic properties, and not for structural purposes.
4) That is why rubbery materials like silicone rubber, Neoprene etc. are routinely used as dielectrics: they are above Tg at room temperature.
5) The interesting behavior observed by NASA for HDPE dielectric may be due to the its properties near Tg, at operating temperature. It would be misguided to insist on a dielectric chosen for its structural properties rather than its electromagnetic purposes for providing thrust (including nonlinear behavior of complex permittivity and piezoelectric properties).
6) What has been written about group velocity in these threads, is incorrect, regarding HDPE near Tg. What was written about group velocity was from people assuming that the electric permittivty was a constant. They did not consider its temperature dependence.
Once the dielectric is melted into a liquid, at the bottom of the EM Drive cavity, it cannot, upon cooling, recover its previous shape. Melting deformation is permanent, it is not elastic or viscoelastic.
That is how injection molding and extrusion works: at the melting temperatures of the polymers.
If the HDPE dielectric melted in the NASA experiments, as some people have proposed, it would be easy to verify: the dielectric would have melted at the bottom of the EM Drive and would have taken the shape (molded itself) into the shape of the bottom of the EM Drive.
It is trivial to check whether the dielectric in NASA's test would have exceeded its melting point: the HDPE dielectric would be in a puddle at the bottom of the EM Drive. The evidence is to the contrary: the dielectric was able to be re-used and it preserved its shape.
The following photograph shows the dielectric (PTFE in this case) to not have melted, in the same experiment where there was a problem with the Nylon screws. The dielectric is in its original shape:
I know of no photograph or report from NASA ever indicating that the HDPE dielectric had melted and that it could not be reused.
If the HDPE dielectric was in its previous shape and was able to be reused, then it did not exceed its melting temperature. It may have reached or exceeded its glass transition temperature (Tg), and there is nothing wrong with that, on the contrary, to insist on a dielectric to be below its Tg is misguided, as one would never use rubbery materials like Neoprene and silicone rubber as dielectrics, under such premise. -
#1384 by SeeShells on 18 Apr, 2016 17:11
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If a polymer exceeds it melting point, it will not be in its previous shape anymore but it will be in a puddle of liquid, due to gravity.
https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335583#msg1335583...
Yes
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
Shell
1) It was described as "melting". But the photographs did not show melting: the screws did not turn into a viscous liquid, as it happens when the melting temperature was exceeded. Instead, what happened was that the Tg was exceeded, thus the screws became rubbery, the heat deflection temperature was exceeded and viscoelastic-plastic material behavior took place. The "melting" description was a non-technical non-material-science description used in a forum to describe the rubbery behavior of the screws.
2) A screw has a structural purpose: it has to support a given stress, and thus it is preferable for a screw to be made of a stiff elastic material. That is why screws are usually not made of rubber.
3) The dielectric in a resonant cavity like the EM Drive is not used for any structural purpose, The dielectric is not used as screw. It is misguided to think so. The dielectric in an electromagnetic resonant cavity like the EM Drive is there for its electromagnetic properties, and not for structural purposes.
4) That is why rubbery materials like silicone rubber, Neoprene etc. are routinely used as dielectrics: they are above Tg at room temperature.
5) The interesting behavior observed by NASA for HDPE dielectric may be due to the its properties near Tg, at operating temperature. It would be misguided to insist on a dielectric chosen for its structural properties rather than its electromagnetic purposes for providing thrust (including nonlinear behavior of complex permittivity and piezoelectric properties).
6) What has been written about group velocity in these threads, is incorrect, regarding HDPE near Tg. What was written about group velocity was from people assuming that the electric permittivty was a constant. They did not consider its temperature dependence.
Once the dielectric is melted into a liquid, at the bottom of the EM Drive cavity, it cannot, upon cooling, recover its previous shape. Melting deformation is permanent, it is not elastic or viscoelastic.
That is how injection molding and extrusion works: at the melting temperatures of the polymers.
If the HDPE dielectric melted in the NASA experiments, as some people have proposed, it would be easy to verify: the dielectric would have melted at the bottom of the EM Drive and would have taken the shape (molded itself) into the shape of the bottom of the EM Drive.
It is trivial to check whether the dielectric in NASA's test would have exceeded its melting point: the HDPE dielectric would be in a puddle at the bottom of the EM Drive. The evidence is to the contrary: the dielectric was able to be re-used and it preserved its shape.
If the HDPE dielectric was in its previous shape and was able to be reused, then it did not exceed its melting temperature. It may have reached or exceeded its glass transition temperature (Tg), and there is nothing wrong with that, on the contrary, to insist on a dielectric to be below its Tg is misguided, as one would never use rubbery materials like Neoprene and silicone rubber as dielectrics, under such premise.
Dr. Rodal,
This isn't a disagreement with you on the properties of dielectrics and their melting temperatures or even if the dielectrics melted and flowed within a frustum. They didn't.
What my post to you and others was about the the gap between the threads of the nylon screws along with the microwave heating actions within those gaps caused excessive heating causing the nylon screw to deform.
Drive builders must take this into account if they are going to secure the dielectric plugs in a frustum. They must be made aware this this could happen and there exists a solution to prevent it happening.
Shell -
#1385 by rfmwguy on 18 Apr, 2016 17:27
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I think its fair to mention again that EW believes force was measured without a dielectric. While there is some debate about HDPE, dielectrics have not been 100% proven to enhance the effect. Its still up to the builder to decide which avenue they choose. No agreed upon theory = no agreed upon material composition. Some may have preferences or assumptions, but so far, there is no "right way" to build one.
Dr. Rodal,
This isn't a disagreement with you on the properties of dielectrics and their melting temperatures or even if the dielectrics melted and flowed within a frustum. They didn't.
What my post to you and others was about the the gap between the threads of the nylon screws along with the microwave heating actions within those gaps caused excessive heating causing the nylon screw to deform.
Drive builders must take this into account if they are going to secure the dielectric plugs in a frustum. They must be made aware this this could happen and there exists a solution to prevent it happening.
Shell -
#1386 by Rodal on 18 Apr, 2016 17:29
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...
My point is on the other hand:
Dr. Rodal,
This isn't a disagreement with you on the properties of dielectrics and their melting temperatures or even if the dielectrics melted and flowed within a frustum. They didn't.
What my post to you and others was about the the gap between the threads of the nylon screws along with the microwave heating actions within those gaps caused excessive heating causing the nylon screw to deform.
Drive builders must take this into account if they are going to secure the dielectric plugs in a frustum. They must be made aware this this could happen and there exists a solution to prevent it happening.
Shell
1) To fully accept that the Nylon screws got so hot that they ceased to be functional. To point out that that behavior of the Nylon screws rather than pointing to the non-functionality of the dielectric HDPE (as was hinted by others, not by you) it may point to something that has been neglected in these threads up to now:
2) that the HDPE dielectric in NASA's test likely got to be hot enough to be at its glass transition temperature (Tg) or above Tg.
3) that the HDPE dielectric in NASA's test getting to Tg or above Tg rather than being something negative, may be the reason why HDPE worked so well as a dielectric for NASA's tests: because of HDPE electromagnetic properties at Tg or above Tg (instead of the dielectric properties below Tg).
4) that was has been written about the group velocity in the EM Drive thread is incorrect regarding NASA's tests, because people that wrote about the group velocity in NASA's tests did not take into account what happens to the group velocity at a temperature in the Tg range -
#1387 by Rodal on 18 Apr, 2016 17:34
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I think its fair to mention again that EW believes force was measured without a dielectric. While there is some debate about HDPE, dielectrics have not been 100% proven to enhance the effect. Its still up to the builder to decide which avenue they choose. No agreed upon theory = no agreed upon material composition. Some may have preferences or assumptions, but so far, there is no "right way" to build one.
Dr. Rodal,
This isn't a disagreement with you on the properties of dielectrics and their melting temperatures or even if the dielectrics melted and flowed within a frustum. They didn't.
What my post to you and others was about the the gap between the threads of the nylon screws along with the microwave heating actions within those gaps caused excessive heating causing the nylon screw to deform.
Drive builders must take this into account if they are going to secure the dielectric plugs in a frustum. They must be made aware this this could happen and there exists a solution to prevent it happening.
Shell
This statement does not tell the correct story to somebody interested in measuring the greatest anomalous force/InputPower:QuoteI think its fair to mention again that EW believes force was measured without a dielectric.
When using a torsional pendulum, NASA's report is explciit: even when increasing the power input by a factor of 10, NASA could measure no significant anomalous force without a dielectric.Quote from: Brady et.alThere appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be evaluated using numerous COMSOL® iterations to arrive at a viable thruster solution. 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.
page 18 of
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
David A. Brady*, Harold G. White†, Paul March‡, James T. Lawrence§, and Frank J. Davies**
NASA Lyndon B. Johnson Space Center, Houston, Texas 77058
You are using a qualitative statement regarding a completely different measurement system (a teeter-totter) , with a different EM Drive (aluminum instead of copper), in a different mode shape, which was never documented in an official report: using a teeter-totter instead of a torsional pendulum:Quote from: Star-Drive on 10/31/2015 03:21 PMAs to testing a frustum without a dielectric, we have tested this configuration in an aluminum frustum on a new teeter-totter balance using hundreds of watts of 2.45 GHz RF power, and we MAY have observed a non-zero thrust results while in-air.
Notice that besides stating the differences in testing equipment, EM Drive material, mode shape and frequency, the statement states "MAY" in capitals and that all that it states is that the force measurement MAY have been non-zero, when using hundreds of watts.
Although many readers are familiar with this by now, it bears emphasizing, rfmwguy, that the figure of merit in EM Drive experiments is not the force measured, but the force/PowerInput, as for example in a comparison with a photon rocket, as well as being the figure of merit for Shawyer, McCulloch and NSF member Dr. Notsosureofit. And NASA having to use hundreds of watts to obtain a non-zero measurement without a dielectric is nothing to brag about
. The 2014 report's measurements with a dielectric in mode TE012 used only 2 watts to get a significant force. The 2014 measurements of no significance force without a dielectric went up to only 30 watts, instead of requiring hundreds of watts to MAY be get a non-zero measurement in the brief Oct 2015 unpublished news.
You fail to take into account
1) the measurement equipment differences (teeter-totter vs torque pendulum),
2) the quantitative differences between dielectric and no dielectric in either equipment.
3) most importantly, you fail to compare based on the figure of merit: force/PowerInput, as you completely disregard the amount of power that it took for NASA to "MAY be" get a force without a dielectric.
If one is going comment on NASA's test on a completely different experiment (a teeter-totter) you should be comparing the actual experimental numerical results in the teeter-totter with and without a dielectric. You should at least describe qualitatively what was the difference between results with and without a dielectric in the different equipment (teeter totter instead of torsional pendulum). And you should compare based on force/PowerInput, instead of just force.
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PS: statements concerning the fact that DIY builders are free to decide whatever they want are non-sequiturs, of course DIY builders may do whatever they want (as long as we don't get a DIY dictator ruling over all DIY builders ) , but they are entitled to have clear and complete facts, instead of qualitative statements that "dielectrics are no longer required" based on what "MAY" have been measured as "non-zero" in a different type of testing equipment, without providing the actual comparison between dielectric and non-dielectric in the teeter-totter experiment and without comparing the difference in results between teeter-totter and torsional pendulum.
It is misleading to state "dielectrics are no longer necessary" when the anomalous force with the dielectric in a teeter-totter may be X times greater than the force measured without a dielectric in the same teeter-totter, and you fail to mention what is the factor of X difference between both results. Not providing the factor of X difference, and ignoring the amount of power required to produce a measurable force, is prejudicial to the reader that is interested in measuring the greatest force/InputPower possible.
The issue is not how to get a "non-zero measurement", but the issue is how to get the greatest anomalous force/InputPower, and the evidence from NASA continues to be that NASA measures the greatest anomalous force/InputPower with a dielectric insert, rather than without it.
Statements regarding "theory" in this regard are also a non-sequitur. It is an experimental fact that NASA reported no significant thrust when using a torque pendulum, and that it took hundreds of watts, a much greater InputPower to get a "non-zero measurement" without a dielectric. This has nothing to do with theory, it just follows from NASA's experiment. -
#1388 by rfmwguy on 18 Apr, 2016 17:52
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A lot has happened and has been reanalyzed since EWs experiment in 2014 and their conference paper. While I cannot be any more specific that I have already have been, it is no longer a certainty that a dielectric is required.
I think its fair to mention again that EW believes force was measured without a dielectric. While there is some debate about HDPE, dielectrics have not been 100% proven to enhance the effect. Its still up to the builder to decide which avenue they choose. No agreed upon theory = no agreed upon material composition. Some may have preferences or assumptions, but so far, there is no "right way" to build one.
Dr. Rodal,
This isn't a disagreement with you on the properties of dielectrics and their melting temperatures or even if the dielectrics melted and flowed within a frustum. They didn't.
What my post to you and others was about the the gap between the threads of the nylon screws along with the microwave heating actions within those gaps caused excessive heating causing the nylon screw to deform.
Drive builders must take this into account if they are going to secure the dielectric plugs in a frustum. They must be made aware this this could happen and there exists a solution to prevent it happening.
Shell
This statement is not completely correct:QuoteI think its fair to mention again that EW believes force was measured without a dielectric.
When using a torsional pendulum, NASA's report is explciit: even when increasing the power input by a factor of 10, NASA could measure no significant anomalous force without a dielectric.Quote from: Brady et.alThere appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be evaluated using numerous COMSOL® iterations to arrive at a viable thruster solution. 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.
page 18 of
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
David A. Brady*, Harold G. White†, Paul March‡, James T. Lawrence§, and Frank J. Davies**
NASA Lyndon B. Johnson Space Center, Houston, Texas 77058
You are confusing a statement regarding a completely different measurement system which was never documented in an official report: using a teeter-totter instead of a torsional pendulum.
This is very misleading and prejudicial. If you are going to be commenting on NASA's test on a completely different experiment (a teeter-totter) you should be comparing the experimental results in the teeter-totter with and without a dielectric.
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PS: statements concerning what DoItYourself people may do are non-sequiturs, of course people may use , but they are entitled to having clear facts, instead of misleading ones.
Statements regarding "theory" are also a non-sequitur. It is an experimental fact that NASA reported no significant thrust when using a torque pendulum, this has nothing to do with theory, it just follows from NASA's experiment.
"PS: statements concerning what DoItYourself people may do are non-sequiturs, of course people may use , but they are entitled to having clear facts, instead of misleading ones."
Your inference and opinion on "Doityourself people" have been clearly noted. -
#1389 by X_RaY on 18 Apr, 2016 21:12
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X_Ray , since you are experimenting with different frequencies, why not try all of what NASA worked with (where in some instances the Mode was in TM ...... of course you'd need to change them by the up-scaling factor.
Sure I could do so, but I don't see any reason for this.
For the NASA results the frequencies and modes of the frustum shaped cavities listed on emdrive.wiki are backed with precise calculations, field simulations(Comsol) and at least measurements, especially EW published a lot of stuff in this regard. Since Maxwell equations are linear you can choose a cavity and scale it like you want, as shown/verified during the last few days. -
#1390 by frobnicat on 18 Apr, 2016 21:17
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.../...
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
Shell
Should rather stay away from this heated debate but : Shell, where exactly comes this "Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting" ? I don't remember any public statement of Paul March (aka StarDrive) indicating such "Teflon tape" counter measure to the melting problem, nor that there was a clear diagnosis such as "small gaps left the threads the microwave actions around the threads heated up the nylon screw". My understanding was that the Nylon screws were holding (through) a PTFE disk, the thick slab of dielectric, not that any thin Teflon tape was involved in wrapping things.
Aside from that, from my viewpoint about torsion pendulum EW's tests, glass transition is relevant not as much as per its accompanying transition in electromagnetic properties (a fact I was utterly ignorant of before indications of dr Rodal, thanks) but quite specifically in that it can transform a roughly linear ramp-up in temperature (as expected from a constant source of inductive heating, at start) in a nonlinear effect that can take the shape of a fast rise followed by a plateau (below TG, fast transition through TG, above TG).
In the very specific setting of torsion pendulum EW's tests where we know that the axis of rotation of arm is not strictly vertical and hence displacement measures are sensitive proportionately to displacement in center of mass (not requiring first nor second derivative wrt time of CoM shift, yada yada) such nonlinear mechanical effect in the capacity of structural element to deform under stress (tension in the screws for instance) could very effectively mimic the typical signature of an on/off "thrusting" effect. EW's analysis rely heavily on the qualitative aspect of the recorded signals (displacement vs time) with a central argument being that given the time constants involved with heat transfers, spurious effects related to temperature would have very different shapes (basically that of smooth ramp-up, on the order of 10s of seconds) instead of the observed fast (but not quite fast enough) rise to plateau.
My take (bet) is that, one of the reason why EW experimenters, when on their slightly axis tilted horizontal pendulum see something that looks like thrust with dielectric slabs and not without, they would actually see a spurious effect of dielectric's mass shifting in position thanks to glass transition of the holding screws (and thanks to gravity). Should they solve this issue of mass shifting when using a dielectric, they should record the same level of thrust with or without dielectric : none. None above a fraction of 3.33µN/kW at least.
Of course different experimental settings come with different systematic errors, it is certainly possible to find other ways to get results that look roughly like on/off thrust signatures through other mechanisms, by tinkering hard enough. I don't think EW is in position of pursuing/issuing a clear negative conclusion to this whole story of EM drive effect because their (institutional) survival depends on ongoing promising results, forever, short of an impossible to reach fully documented reproducible positive.
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#1391 by Rodal on 18 Apr, 2016 22:35
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My understanding was that the Nylon screws were holding (through) a PTFE disk, the thick slab of dielectric, not that any thin Teflon tape was involved in wrapping things.
I have the same understandingMy take (bet) is that, one of the reason why EW experimenters, when on their slightly axis tilted horizontal pendulum see something that looks like thrust with dielectric slabs and not without, they would actually see a spurious effect of dielectric's mass shifting in position thanks to glass transition of the holding screws (and thanks to gravity). Should they solve this issue of mass shifting when using a dielectric, they should record the same level of thrust with or without dielectric : none. None above a fraction of 3.33µN/kW at least.
1) That's an interesting observation that should be easy enough to demonstrate in experiments to validate or nullify the hypothesis of thrust.
2) Please note the October 2015 remark by Star-Drive that using hundreds of watts (rather than less than 30 watts for the 2014 experiments that showed no significant force) without a dielectric NASA "MAY" (it bears repeating that he wrote MAY in capital letters) have had a non-zero force measurement, that this measurement was done in a teeter-totter measuring device rather than a torsional pendulum, and hence your proposal would have to accommodate the fact that these measurements showed the force/input power to be greater with a dielectric than without a dielectric by an "X" multiplier, also when using a teeter-totter measuring device.I don't think EW is in position of pursuing/issuing a clear negative conclusion to this whole story of EM drive effect because their (institutional) survival depends on ongoing promising results, forever, short of an impossible to reach fully documented reproducible positive.
I think that the people at NASA Eagleworks (Dr. White, Paul March, Frank Davies, et.al.) are people of high personal and scientific integrity that are devoting these important years in their life to the noble pursuit of very high aspirational goals to enable mankind to leave low Earth orbit (rather than continuing the sad story of sending astronauts back and forth to Low Earth Orbit ever since Nixon decided to dismantle the Saturn V and the Apollo Applications Program more than 40 years ago). I applaud them in this regard, as difficult their goals are. I think that Dr. White, March, Davies, et.al. choose to do this not because it is easy, but because it is hard:
I think that if they conclude a clear negative conclusion on the present efforts they will publish such results.
NASA already, in their 2014 Brady et.al report, reported negative results of what was claimed by other researchers:
1) no significant anomalous force, even when using a power 10 times greater, when a dielectric insert is not used. Hence NASA practically nullifying the claimed results of Shawyer and Yang that a dielectric was not needed or Shawyer's claim that it detracts from the anomalous thrust.
2) no increase in anomalous thrust from the Cannae device with grooves, therefore effectively nullifying Guido Fetta's patent claims of increased anomalous force due to such grooves.
Also there is actually clear precedence for researchers at a Government Institution publishing results that close their multi-year program of research into propellant propulsion: for example Dr. Brito in Argentina for several years, preceding Dr. White, preceding or concurrently with Prof. Woodward and preceding Roger Shawyer SPR Ltd., pursued propellant less propulsion both experimentally and theoretically at a research institution in Argentina, including project funding from the US Air Force (*) as well and published in peer-reviewed publications, but eventually closed this program with a clear negative in the AIAA paper with Marini and Galian (and the peer-reviewed article by Marini and Galian) using a Cavendish style pendulum with a self-integrated power source (batteries).
In this regard, I hope that NASA Eagleworks is able to pursue the program with John Hopkins using a Cavendish pendulum with a self-integrated battery (discussed in NASA's 2014 report of Brady et.al.).
___________________________
(*) funding included U.S. Air Force Research Laboratory under its Windows-on-Science Program, Grant FA8655-03-1-2A21, NASA BPP Project for procuring that help, Argentine National Agency for the Advancement of Science and
Technology (ANPCyT), Grant FONCyT—PICT-2002-10-10592, and “Instituto Universitario Aeronautico” of Cordoba -
#1392 by FattyLumpkin on 18 Apr, 2016 23:43
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Hello X_Ray, yes I was not suggesting you attempt to simulate everything on the data chart,
only it was argue many pages back the frustum was not design for TM212 mode.(as I recall).
The only sim. I'd like you to do (if you would) is where the frequency is at 1.9371 GHz, TM212 mode, 50 Watts power and produced 110 Micronewtons. This as you can see was not the best thrust/power ratio, but was the highest amount of thrust and in a different mode.
I didn't know if downscaling as before would work as well in these conditions. Thank you, FL -
#1393 by tchernik on 18 Apr, 2016 23:47
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Just to say that I appreciate this forum's continued commitment with the truth, and the efforts you people do for bringing that truth here, whatever it is.
It is easy to lose perspective of things and become too partisan and supportive, or become too skeptic and cynic. But reality is rarely exactly where we expect it to be.
Thus the need of staying in the just and fair middle: assume good faith from all parties and let the experiments and data speak for themselves. -
#1394 by FattyLumpkin on 18 Apr, 2016 23:57
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Dr. Rodal and Dave, I searched for Q thrusters on nasaspaceflight.com, and there is a grand total one 1 (one) page on the subject, with no posts in the last 300 days. Are Q thrusters being lumped together with Em and Cannae drives in the EWL paper now in peer review?
I also checked "Woodward effect" NSF and there are 30 some odd pages to be found, but a great deal of comment is located here on NSF Emdrive. Is the topic of Q thrusters to be addressed here on Emdrive? or ? Thank you, FL -
#1395 by rfmwguy on 19 Apr, 2016 00:02
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Dr. Rodal and Dave, I searched for Q thrusters on nasaspaceflight.com, and there is a grand total one 1 (one) page on the subject, with no posts in the last 300 days. Are Q thrusters being lumped together with Em and Cannae drives in the EWL paper now in peer review?
Q Thruster is EW's name for the EMDrive...same general concept.
I also checked "Woodward effect" NSF and there are 30 some odd pages to be found, but a great deal of comment is located here on NSF Emdrive. Is the topic of Q thrusters to be addressed here on Emdrive? or ? Thank you, FL -
#1396 by SeeShells on 19 Apr, 2016 00:12
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We all need to remember.
"Any time scientists disagree, it's because we have insufficient data. Then we can agree on what kind of data to get; we get the data; and the data solves the problem. Either I'm right, or you're right, or we're both wrong. And we move on. That kind of conflict resolution does not exist in politics or religion." Neil deGrasse Tyson
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#1397 by Rodal on 19 Apr, 2016 00:22
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1) To state that "Q Thruster" is NASA's Eagleworks name for the EM Drive...same general concept, would be like saying that rectangle is somebody's name for a square...same general concept.Dr. Rodal and Dave, I searched for Q thrusters on nasaspaceflight.com, and there is a grand total one 1 (one) page on the subject, with no posts in the last 300 days. Are Q thrusters being lumped together with Em and Cannae drives in the EWL paper now in peer review?
Q Thruster is EW's name for the EMDrive...same general concept.
I also checked "Woodward effect" NSF and there are 30 some odd pages to be found, but a great deal of comment is located here on NSF Emdrive. Is the topic of Q thrusters to be addressed here on Emdrive? or ? Thank you, FL
Not precisely, a square is a subset of rectangles, not all rectangles are squares
Ditto for the Q-Thruster, according to Dr. White's definition all EM Drives are Q-Thrusters but not all Q-Thrusters are EM Drives.
Q-Thruster is not the "same general concept" as the EM Drive. Instead, Q-Thruster is a more general concept than the EM Drive.
As I explained in a previous post, "Q Thruster" is Dr. White's name for any and all thrusters whose thrust can be explained as due to Dr. White's Quantum Vacuum theory.
Q-Thrusters include microwave cavity thrusters like:
1) the truncated cone EM Drive
2) Cannae's flying-saucer shaped drive
3) a horn-shaped resonant microwave cavity
4) a pizza-slice shaped resonant microwave cavity
5) a cauliflower-shaped resonant microwave cavity
6) and so and on
But Q-Thruster also includes completely different thrusters, for example, as explained previously, Prof. Woodward's and Paul March's Mach Lorentz Thrusters are not at all like the EM Drive, that are not at all microwave resonant cavities:
* the MLT thruster does not use microwaves
* the MLT thruster is not a resonant cavity, and it is not a truncated cone cavity, not a even a waveguide
but the MLT thruster is a "Q Thruster" tested by NASA's Eagleworks.
Ditto for the Serrano Field Effect Thruster, built by Gravitec Inc. at the request of Boeing and DARPA tested by NASA in 2013: Serrano's drive is a Q thruster, (according to Dr. White) but Serrano's drive is not at all an EM Drive, it is not even a resonant cavity (the Wikipedia entry is wrong in this respect)
There are countless numbers of rectangles that are not squares.
There are countless numbers of Q-Thrusters that are not EM Drives.
Wikipedia has wisely decided that "Q-Thrusters" is a different Wiipedia entry from "RF resonant cavity thruster" (previously EM Drive), as the EM drive is a small subset of "Q-Thrusters" per Dr. White, and according to Shawyer the EM Drive is not a Q-Thruster (since according to Shawyer the Quantum Vacuum is not needed to explain the EM Drive, according to Shaywer all you need is Classical Physics: Newton and Maxwell).
________________________________Dr. Rodal and Dave,...are Q thrusters being lumped together with Em and Cannae drives in the EWL paper now in peer review? ...Thank you, FL
2) I'm sure that Dave (or others) has not had access to future papers that NASA Eagleworks is planning to publish in peer-review in renowned journals. Such papers are held confidential between the authors and the peer reviewers. The peer reviewers know the content of the paper being reviewed, but Dave (or anybody else posting information here) are not peer-reviewers. Peer reviewers are sworn to keep their information confidential. They would never post piecemeal information on a forum.
In other words: do not assume that Dave (or any others) have accurate advanced knowledge of what NASA is doing. Any such assumption you may make is completely at your own peril.
I think that discussion of what any unreleased, future NASA papers may or may not contain is futile. Case in point: Dr. White's and Paul March's last paper, on the Quantum Vacuum, did not even discuss the EM Drive or any other Q-Thruster, it just discussed the Quantum Vacuum :
White, H. , Vera, J. , Bailey, P. , March, P. , Lawrence, T. , Sylvester, A. and Brady, D. (2015) Dynamics of the Vacuum and Casimir Analogs to the Hydrogen Atom. Journal of Modern Physics, 6, 1308-1320.
doi: 10.4236/jmp.2015.69136.
(Dated: March 4, 2015)
http://www.scirp.org/journal/PaperInformation.aspx?paperID=59027
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#1398 by FattyLumpkin on 19 Apr, 2016 00:50
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Dr. Rodal, suffice it to say that Q thrusters are NOT in the EWL paper now in review? Only Em and Cannae drives? thnx , K Cauliflower shaped? LOL
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#1399 by spupeng7 on 19 Apr, 2016 03:46
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I have read that some emDrive researchers claim that the emdrive frustum must be set in motion in order for the thrust effect to be observed. I would assume this actually means that the frustum must be accelerated, if for only a small amount of time (we all have velocity around the sun already). Remembering back to high school physics now, aren't an accelerating object and an object in a gravitation field indistinguishable as far as i forget if it is Special or General Relativity? Since all emdrive experiments were performed on earth, and thus were performed within a gravitational field, this would seem to contradict the claim that the frustum must be set in motion in order to observe the thrust, as it would be impossible to conduct an experiment without these conditions baked in. .... Sorry for the amateur observation, back to the real scientists!
Nice observation CriX,
these insights are what keep me coming back to this forum. I always learn something, even if it is something I already somehow managed to forget
Attached observations from the wonderous Erwin Schrodinger were recommended by Fernando Minotti.
. The 2014 report's measurements with a dielectric in mode TE012 used only 2 watts to get a significant force. The 2014 measurements of no significance force without a dielectric went up to only 30 watts, instead of requiring hundreds of watts to MAY be get a non-zero measurement in the brief Oct 2015 unpublished news.