Quote from: deltaMass on 06/11/2015 11:08 pm@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.You are 100% correct. Trouble is, I cannot find sources that quantify entropy. Its certainly post-newtonian physics, which was solely focused on the 5% of "regular" matter and energy. I also agree that a Frustum may be happenstance, but an "opaque effect" may be focused there. The reason I say opaque is that if it was "solid" the Frustum would literally blow apart. Its similar to gravity. We have yet to determine how to make something "opaque" to it, something it affects less than normal matter.
@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.
Quote from: Rodal on 06/12/2015 12:44 amQuote from: WarpTech on 06/11/2015 10:18 pm...Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.ToddProf. Yang's EM Drive is significantly longer than Shawyer'sDescription Mode Shape Length (m) Db (m) Ds (m) Frequency (GHz) Q Force / PowerInput (mN/kW)Shawyer Demo TE012 0.187 0.28 0.14921 2.45 45000 80-243Yang TE012 0.24 0.201 0.1492 2.45 1531 1070Both have the same frequency, same mode shape, same Small Diameter Yang achieves 10 to 5 times greater force/input power by operating with 29 times lower Q with a 28% longer EM Drive and 39% smaller big diameter. All the opposite of what Shawyer recommends.The wavelength is 299700000 m/s /(2.45*10^9 1/s) = 0.122 mSo Yang's EM Drive (which has the same small diameter as Shawyer's Demo) has a length (0.24 - 0.187) = 0.053 mYang's EM Drive is therefore about 1/2 wavelength longer than Shawyer's EM Drive truncated cone lengthThe most important parameter to Zeng & Fan is the cone half-angle. It is drastically different between them:Shawyer (180/Pi) ArcTan[(0.28 - 0.14921)/(2*0.187)] = 19.275 degreesYang (180/Pi) ArcTan[(0.201 - 0.1492)/(2*0.24)] = 6.159 degreesShawyer's EM Drive has a cone half-angle more than 3 times greater.Yang's EM Drive is closer to a cylinder, which according to Zeng & Fan results in much greater attenuation.
Quote from: WarpTech on 06/11/2015 10:18 pm...Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.ToddProf. Yang's EM Drive is significantly longer than Shawyer'sDescription Mode Shape Length (m) Db (m) Ds (m) Frequency (GHz) Q Force / PowerInput (mN/kW)Shawyer Demo TE012 0.187 0.28 0.14921 2.45 45000 80-243Yang TE012 0.24 0.201 0.1492 2.45 1531 1070Both have the same frequency, same mode shape, same Small Diameter Yang achieves 10 to 5 times greater force/input power by operating with 29 times lower Q with a 28% longer EM Drive and 39% smaller big diameter. All the opposite of what Shawyer recommends.The wavelength is 299700000 m/s /(2.45*10^9 1/s) = 0.122 mSo Yang's EM Drive (which has the same small diameter as Shawyer's Demo) has a length (0.24 - 0.187) = 0.053 mYang's EM Drive is therefore about 1/2 wavelength longer than Shawyer's EM Drive truncated cone length
...Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.Todd
Quote from: Rodal on 06/12/2015 01:20 amQuote from: Rodal on 06/12/2015 12:44 amQuote from: WarpTech on 06/11/2015 10:18 pm...Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.ToddProf. Yang's EM Drive is significantly longer than Shawyer'sDescription Mode Shape Length (m) Db (m) Ds (m) Frequency (GHz) Q Force / PowerInput (mN/kW)Shawyer Demo TE012 0.187 0.28 0.14921 2.45 45000 80-243Yang TE012 0.24 0.201 0.1492 2.45 1531 1070Both have the same frequency, same mode shape, same Small Diameter Yang achieves 10 to 5 times greater force/input power by operating with 29 times lower Q with a 28% longer EM Drive and 39% smaller big diameter. All the opposite of what Shawyer recommends.The wavelength is 299700000 m/s /(2.45*10^9 1/s) = 0.122 mSo Yang's EM Drive (which has the same small diameter as Shawyer's Demo) has a length (0.24 - 0.187) = 0.053 mYang's EM Drive is therefore about 1/2 wavelength longer than Shawyer's EM Drive truncated cone lengthThe most important parameter to Zeng & Fan is the cone half-angle. It is drastically different between them:Shawyer (180/Pi) ArcTan[(0.28 - 0.14921)/(2*0.187)] = 19.275 degreesYang (180/Pi) ArcTan[(0.201 - 0.1492)/(2*0.24)] = 6.159 degreesShawyer's EM Drive has a cone half-angle more than 3 times greater.Yang's EM Drive is closer to a cylinder, which according to Zeng & Fan results in much greater attenuation.Thank you for validating everything I just said!
Quote from: rfmwguy on 06/12/2015 12:33 amQuote from: deltaMass on 06/11/2015 11:08 pm@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.You are 100% correct. Trouble is, I cannot find sources that quantify entropy. Its certainly post-newtonian physics, which was solely focused on the 5% of "regular" matter and energy. I also agree that a Frustum may be happenstance, but an "opaque effect" may be focused there. The reason I say opaque is that if it was "solid" the Frustum would literally blow apart. Its similar to gravity. We have yet to determine how to make something "opaque" to it, something it affects less than normal matter.I think you are very confused by what you are referring to. Entropy is not a weird, unknown or mysterious force (at least to scientists who regularly work with thermodynamics).I'd like to clarify this a little since one of the biggest differences I've noticed between pseudo science and good science is precise definitions of terms.You referred to entropy as a force a couple times. Entropy is not a force (It has units of energy per temperature.) This doesn't mean that it can't produce an effective force, but this would be the same way that a density gradient in a gas would cause an effective force (The higher density causes a higher pressure, which is force normalized by area)(...)
Quote from: meberbs on 06/12/2015 01:50 amQuote from: rfmwguy on 06/12/2015 12:33 amQuote from: deltaMass on 06/11/2015 11:08 pm@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.You are 100% correct. Trouble is, I cannot find sources that quantify entropy. Its certainly post-newtonian physics, which was solely focused on the 5% of "regular" matter and energy. I also agree that a Frustum may be happenstance, but an "opaque effect" may be focused there. The reason I say opaque is that if it was "solid" the Frustum would literally blow apart. Its similar to gravity. We have yet to determine how to make something "opaque" to it, something it affects less than normal matter.I think you are very confused by what you are referring to. Entropy is not a weird, unknown or mysterious force (at least to scientists who regularly work with thermodynamics).I'd like to clarify this a little since one of the biggest differences I've noticed between pseudo science and good science is precise definitions of terms.You referred to entropy as a force a couple times. Entropy is not a force (It has units of energy per temperature.) This doesn't mean that it can't produce an effective force, but this would be the same way that a density gradient in a gas would cause an effective force (The higher density causes a higher pressure, which is force normalized by area)(...)its the nature of entropy that interests me and there are knowns due to classic thermodynamics. from a plain language standpoint, we measure and discuss 5% of the known universe, despite the majority of it being dark mass & energy. Some knowns could crossover, but odds are that cosmic expansion occurs because of a force/energy/mass we know little about. Therein lies a more than reasonable chance of significant discoveries, emdrive or otherwise. maybe we can agree that expansion due to dark energy is a natural force we do not fully comprehend yet.EditPerhaps I should have said entropic force: https://en.m.wikipedia.org/wiki/Entropic_forceOne final edit: Unification of Dark Matter and Dark Energy in a Modified Entropic Force Model - http://arxiv.org/pdf/1009.1506v3Guess I am a couple of years behind
...There clearly isn't enough "thrust" (if there is thrust) to compensate friction, at least at those speeds. Actually there isn't even prograde thrust at all that would limit the decay, or if there is it appears very unconclusive to my eye, as the decay seems to continue at same rate, within margins of noise. Only in retrograde mounting there is maybe slightly more speed loss rate at activation (maybe adepts of Shawyer's theories will be delighted to see here an illustration of the distinction between motor mode and generator mode ?).Which begs the question of what kind of friction there is ? Aerodynamic drag would tend to fall with speed, while the curves show a near linear decay in speed, constant deceleration, constant drag force... it looks more like a (very low) dry friction, until it falls below 150 and drag gets even higher. That looks contradictory to aerodynamic drag being the main contributor to the dissipative factor. This is to be characterised properly, especially if thrust effects are to be evaluated against this drag.I wonder, they do use one of those magnetic globe levitators system, don't they ? Those toys use an active electromagnet feedback system to stabilize altitude and vertical oscillations, on top of the stronger permanent magnet that does the heavy lifting. Couldn't the periods of this feedback enter in resonance or just happen to synchronise with the rotation period, leading to net torque being communicated from the electromagnet to the levitated rig (taking into account small deviations of magnetic materials wrt perfectly axisymmetric geometry) ?
Quote from: WarpTech on 06/12/2015 01:53 am...Thank you for validating everything I just said! Do you think this model will still require a separate resonance chamber as per your original plan?
...Thank you for validating everything I just said!
...It is amazing that Yang achieves record thrust force and record thrust force/powerInput by doing the complete opposite of common wisdom:* lowest Q of any recorded test (common wisdom: highest Q the better)* smallest cone angle, closest to cylinder (common wisdom: highest cone angle the better)* longer cavity than Shawyer's Demo at same small diameter* smaller big diameter than Shawyer's Demo at same small diameter (common wisdom: the larger the big diameter the better)...
Quote from: frobnicat on 06/10/2015 11:51 pm...There clearly isn't enough "thrust" (if there is thrust) to compensate friction, at least at those speeds. Actually there isn't even prograde thrust at all that would limit the decay, or if there is it appears very unconclusive to my eye, as the decay seems to continue at same rate, within margins of noise. Only in retrograde mounting there is maybe slightly more speed loss rate at activation (maybe adepts of Shawyer's theories will be delighted to see here an illustration of the distinction between motor mode and generator mode ?).Which begs the question of what kind of friction there is ? Aerodynamic drag would tend to fall with speed, while the curves show a near linear decay in speed, constant deceleration, constant drag force... it looks more like a (very low) dry friction, until it falls below 150 and drag gets even higher. That looks contradictory to aerodynamic drag being the main contributor to the dissipative factor. This is to be characterised properly, especially if thrust effects are to be evaluated against this drag.I wonder, they do use one of those magnetic globe levitators system, don't they ? Those toys use an active electromagnet feedback system to stabilize altitude and vertical oscillations, on top of the stronger permanent magnet that does the heavy lifting. Couldn't the periods of this feedback enter in resonance or just happen to synchronise with the rotation period, leading to net torque being communicated from the electromagnet to the levitated rig (taking into account small deviations of magnetic materials wrt perfectly axisymmetric geometry) ?One possible source of drag is eddy currents. As the Aluminum cavity sweeps through the magnetic field created by the levitator any change in the field strength will induce currents in the Aluminum. This can happen because of the wobbles seen in the rotation vs time curves. The Aluminum block moves out of center slightly and the magnetic field strength around it is slightly weaker. That will introduce Ohmic losses and the rotation rate will decrease faster than it would if there was no metal.It's an interesting apparatus; very crafty construction. I hope they collect lots of data from it and see what averages out.
...Hmm this gets me thinking about the standing or non-standing waves in the cavity. Let us say, that for some reason attenuation of light is happening at the top end so reflected light is weaker than light from the bottom. As a result the wave is no longer a standing wave and is instead a traveling wave or semi (standing-traveling wave). We all know if you hold a magnet near an aluminum plate and move it it will drag the plate because of the resistance to change in magnetic field. So maybe the semi-traveling waves could do the same to the cavity and drag it along? Does that sound like a possibility?
...1. Q represents energy stored. If ALL the energy is stored, it doesn't do any "work". A lower Q does not imply more waste, it implies more work is being done. It can be due to thrust or heat.2. Smaller cone angle has faster attenuation at higher energy modes = more thrust, lower Q.3. Longer cavity means more stored energy, so she makes up for a lower Q by adding length. (conjecture)4. Thought about this a little more today and the comment from @TheTraveler. (Get well soon!) The wavelength inside the cavity at the small end will be ~half what it is in free space, so the small end is actually probably the right size. It is still important to have a longer frustum to allow the stored energy to be attenuated faster, with fewer bounces. I'm thinking the input port should be 1/4 wavelength from the large end. So resonance happens between the Feed and the large surface. The small end should be far away and designed to attenuate all the possible waves in the spectrum.Todd
Quote from: WarpTech on 06/12/2015 06:50 am...1. Q represents energy stored. If ALL the energy is stored, it doesn't do any "work". A lower Q does not imply more waste, it implies more work is being done. It can be due to thrust or heat.2. Smaller cone angle has faster attenuation at higher energy modes = more thrust, lower Q.3. Longer cavity means more stored energy, so she makes up for a lower Q by adding length. (conjecture)4. Thought about this a little more today and the comment from @TheTraveler. (Get well soon!) The wavelength inside the cavity at the small end will be ~half what it is in free space, so the small end is actually probably the right size. It is still important to have a longer frustum to allow the stored energy to be attenuated faster, with fewer bounces. I'm thinking the input port should be 1/4 wavelength from the large end. So resonance happens between the Feed and the large surface. The small end should be far away and designed to attenuate all the possible waves in the spectrum.ToddShawyer criticizes the use of dielectric inserts inside the EM Drive because they lower the Q (because they have a tan delta > 0 and hence they introduce further losses). However, notice that the use of a dielectric insert can also be criticized from the point of view of lowering the amount of geometrical attenuation.Keeping the geometry of the truncated cone constant, inserting a dielectric has the effect of significantly lowering the natural frequency of the truncated cone. Lowering the natural frequency has the effect of allowing mode shapes to occur that otherwise would have been cut-off without the dielectric. The common practice of inserting the dielectric at the small end, next to the small end base (as done by NASA Eagleworks) has the effect of preventing the cut-off of mode shapes that would have been otherwise cut-off at the small end.Notice that NASA Eagleworks reported thrust force is orders of magnitude smaller than the reported thrust force by the UK and Chinese researchers who don't use dielectric inserts. The effect of the dielectric in lowering the natural frequency and preventing cut-off of modes can be more important than the effect of lowering the Q because the tan delta of these dielectric inserts is very small (for example, for the dielectric used by NASA Eagleworks, HDPE), the tan delta (responsible for lowering Q) is small: only 0.00031 @ 3 GHz while the relative permittivity (responsible for lowering the natural frequency) is not small: 2.26 @ 3 GHz .(http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.htm)So, the geometrical attenuation theory theory of thrust also says that it is a bad idea to use dielectric inserts, because they prevent cut-off, they prevent evanescent waves that would otherwise occur. Thus, the geometrical attenuation theory is in accord with experiments also in this respect, as the experiments show that the highest thrust forces have been produced without dielectric inserts.
FYIThanks to @rfmwguy for the term "Entropic Force". Much more descriptive than "false force" I've been using.Still post-it-noting away on the entropy solution to see if it agrees.The reason here is that if it can be explicitly shown to be the same "Entropic" force, then there is no problem with CoM.
Yes, there is considerable confusion centered about the inclusion of temperature vs information.None the less, unlike the cylindrical cavity where the absolute entropy is maximized in an inertial frame, the tapered cavity distribution is maximized in an accelerated frame of reference.Working from there. Kantor not a big help.
How do we know that the truncated cone entropy distribution is maximized in an accelerated frame or reference?This has been the cause of much discussions in these threads, for example @frobnicat, @deltaMass and @wallofwolfstreet insisting that there is no preferred frame of reference, that the photons don't accelerate, and that everything should be based on frame-indifference. They insist on applying frame-indifference to the cavity.
Quote from: Rodal on 06/12/2015 02:21 pmHow do we know that the truncated cone entropy distribution is maximized in an accelerated frame or reference?This has been the cause of much discussions in these threads, for example @frobnicat, @deltaMass and @wallofwolfstreet insisting that there is no preferred frame of reference, that the photons don't accelerate, and that everything should be based on frame-indifference. They insist on applying frame-indifference to the cavity.To be fair, doesn't the bulk of experimental evidence outside the realm of EM Drives support frame indifference?