Author Topic: EM Drive Developments Thread 1  (Read 798405 times)

Offline Rodal

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Re: EM Drive Developments
« Reply #3060 on: 11/09/2014 03:14 PM »
Yeah I'm hearing you on pseudo-chirality. The monomers aren't chiral, but the repeating units are. We're lucky both PE and PTFE feature those Carbon atoms. Else, chirality would most certainly be dead. In the end, they are chiral. I think your ideas above could be ground breaking stuff. If correct. Certainly an improvement.
I would like somebody to conduct an experiment to show whether indeed the quantum vacuum can impart momentum to a chiral polymer.   It sounds unphysical to me that this can happen (I interpret the Casimir effect as due to van der Waal forces and not to the QV). 

But, hey, I see all these theoretical papers you have uncovered, why don't they show this effect in an actual experiment?

Offline Mulletron

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Re: EM Drive Developments
« Reply #3061 on: 11/09/2014 03:25 PM »
It looks like EMdrive testing may have blundered into such an experiment.

I can't rule out heat either. I see heat in the TE012 plot. See white thrust attachment below. I drew on it in green. There is heat, but there is something else too.

But also attached are screenshots with text circled on exactly why I feel the dielectric is the key here.

« Last Edit: 11/09/2014 03:34 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Rodal

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Re: EM Drive Developments
« Reply #3062 on: 11/09/2014 05:30 PM »
....
Have also to check the heat(t) at the inner surface of copper (might be higher/faster than expected) as a rise of temperature of 10░ on 100cm^3 can give as much "oomph" as 5░ on 200cm^3 or 1░ on 1000cm^3, so lack of thermal conductivity of air might not be the relevant factor to set the typical Tau. + some heat equations...
.....

Maybe if you are working on heat conduction aspects at the cavity's wall, this might help me if you have an idea of the Temp(t) of the inner skin. I know that copper is a very good thermal, conductor. The epoxy behind the (probably) much thinner copper of PCBs end plate not that much. The RF power is dissipated in the first Ám depth skin. What gives instant temperature for the air molecules hitting the inner walls ? This could be a fast alternative to volumetric humid air heating.

Considering the copper thickness to be thermally insulated at z=0 and be subject to heat (energy per unit time, per unit area) "heatFlux" at z=thickness, the complete transient solution for the temperature increase is (where "t" is time in seconds):

temperature=(heatFlux*thickness/thermalConductivity)*( (t/fourierTime) + ((1/2)*((z/thickness)^2) - (1/6)) + temperatureSum

where:

temperatureSum=(heatFlux*thickness/thermalConductivity)*(-(2/(Pi^2))*NSum[(((-1)^n)/(n^2))*(Exp[- (t/fourierTime)*((n*Pi)^2)])*Cos[n*Pi*(z /thickness)], {n, 1, Infinity}])

fourierTime = (thickness^2)/thermalDiffusivity

thermalDiffusivity = thermalConductivity/(density*heatcapacityperunitmass)

For copper, we have the following material properties:

density = 8940 (* kg / (m^3) *);
thermalConductivity = 390  (* W/(m * degK)*);
heatcapacityperunitmass = 385 (* J/(kg * degK)*);

therefore:

thermalDiffusivity = 0.00011331 (m^2)/s

fourierTime = (thickness^2)*8825.38

So we see that steady-state conditions occur very fast due to the very small thickness. 
For example, for thickness = (1/32 inch) * (25.4/1000 m/inch)

fourierTime = 0.00556034 seconds

For example, for thickness = (1/4 inch) * (25.4/1000 m/inch)

fourierTime = 0.355862 seconds


Therefore the temperatureSum term is negligible for time responses in the order of seconds.  The term ((1/2)*((z/thickness)^2) - (1/6)) is also negligible in comparison with (t/fourierTime), so essentially we are left with

temperature ~ (heatFlux*thickness/thermalConductivity)*(t/fourierTime)

                       ~ heatFlux*t*/(density*heatcapacityperunitmass*thickness)

For copper,

density*heatcapacityperunitmass = heatcapacityperunitvolume = 8940*385 (* J/((m^3) * degK)*)

hence,

temperature ~ heatFlux*t*/((3.4419*10^6)*thickness)

where heatFlux has units of W/m^2, thickness in meters and t in seconds.

Calculation of the Heat Flux:

For the transverse electric mode TE012 (p. 18, Table 2. Tapered Cavity Testing: Summary of Results) of the "Anomalous Thrust..." paper by Brady et.al., the Input Power was 2.6 Watts.

Adopting the latest measurement estimates by aero:

SmallDiameter = 0.1549 m
BigDiameter = 0.2793 m

and the input power gets converted into heat (see Greg Egan for discussion), and since the TE012 only the axial magnetic field is non-zero in contact with the big and small diameters, the heat flux is:

heatFlux = (2.6 W) /FluxedArea

where the FluxedArea is:

(Pi/4)*( SmallDiameter^2 + BigDiameter^2 ) / Factor

where

Factor = (ActualDiameter / DiameterOfAreaExperiencingHeatFlux)^2

accounts for the fact that the magnetic flux in mode TE012 contacts only a fraction of the entire circular areas at the ends of the truncated cone.

Therefore,

heatFlux = (32.454 W/m^2) * Factor

Substituting this in our expression for temperature:

temperature ~ heatFlux*t*/((3.4419*10^6)*thickness)
                        ~ (32.454 W/m^2) * Factor * t*/((3.4419*10^6)*thickness)

                        ~ Factor * t*/((1.0605*10^5)*thickness)

So, for thickness = 1/32 inches = 0.0007938 m and Factor = 3 (equivalent to a diameter being heated by the magnetic axial flux as 57.74% of the full diameter)

temperature = (t / 28.059 s) deg C
the temperature increase at 2.6 sec (the pendulum half period) is only 0.09 deg C, and at 30 sec is 1.07 deg C

So, for thickness = 0.02 inches = 0.0005080 m and Factor = 3 (equivalent to a diameter being heated by the magnetic axial flux as 57.74% of the full diameter)

temperature = (t / 17.958 s) deg C
the temperature increase at 2.6 sec (the pendulum half period) is only 0.14 deg C, and at 30 sec is 1.67 deg C



Notice assumptions:

1) All input power is converted into heat
2) axial heat conduction away from heated zone is neglected
3) surface (at z=0) is assumed to be perfectly insulated (by the PCBoard composite material and the surrounding air)
4) diameter being heated by the magnetic axial flux assumed as 57.74% of the full diameter. For other values change "Factor" accordingly.  In the worst case (assuming that the whole diameter is being heated, which is clearly not the case) Factor = 1, and hence the calculated temperatures are 1/3 of the value calculated.
« Last Edit: 11/09/2014 08:37 PM by Rodal »

Online aero

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Re: EM Drive Developments
« Reply #3063 on: 11/09/2014 05:45 PM »
No. The paper says it was 2, 6.25" x 1.06" PE discs. Aero pointed this out I think. That pink area looks to me like a copper cylinder structure to hold those disks in place.


Do you see why my CAD had 6.25" for the minimum diameter possible for the small end now?

I had certainly forgotten about that but it seems that the 6.25 inch diameter of the Brady cavity small end is just as certain as the 160 cm and 280 cm diameter numbers from Shawyer for his cavity's large end.

My measurement technique and correction factors give me high confidence in my estimate of the Brady cavity large end diameter. My confidence level goes down from there because the photo's don't show the small end with nearly as much clarity. Hence choosing the top of the small end diameter (and the bottom to a lesser extent) is in large part, guesswork. That uncertainty affects the measurement of cavity length as well though not as strongly. The length would be somewhat shorter as I took it to be the length of a rectangle with the four corners at the corners of the small end and within the large end. Increasing the height of that rectangle by another 1/2 cm (the difference between 6.25 inches and my estimate) would force a shortening of the rectangle in order that the corners stay on the arc of the small end. A quick check with my ruler tool gives a shortening of about 4 pixels which translates into these updated measurements.

Dimension Inches     cm
 Big Dia.    10.727     27.246
Small Dia. 6.250     15.875
 Length     9.517     24.173
 Best estimate as of 11/9/2014
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Offline frobnicat

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Re: EM Drive Developments
« Reply #3064 on: 11/09/2014 05:46 PM »
Reply #3038 on: November 08, 2014, 04:33:35 PM

...oops, I see 93143 answered faster. Glad to hear someone of the million people...

Reply #3013 on: November 07, 2014, 03:40:29 PM

Your pragmatic inertial frame would be the galaxy, wouldn't it?

So what am I, chopped liver?

don't get what that reference to butchery might mean

That I can say is that there is no such thing as preferred inertial frame (dixit Newton and Einstein). What is "your pragmatic inertial frame" depend on the dynamical system that's to be predicted but what is for sure is that you have the exact same predicted results whatever the inertial frame chosen (why "arbitrary frame") and even accelerated reference frame (done properly). There is often a "natural" frame that makes the calculations more elegant and simple and results easier to interpret, but such frame is still just an arbitrary choice to compare all velocities to the one and same, well, reference. You can also use multiple frames and transform values (velocities, energies ...) from one to another, done properly this is also correct.
But often there is only one frame of reference and many velocities measured relative to this one frame once it's chosen. It appears this is causing mental confusion, to be clear I repeat : many velocities don't mean many frames of references (and the difficulties that go with such frame changes, though they are very well understood and surmountable).

So, the one "natural" frame chosen depend on the subject, for a satellite at earth orbit that would earth centre, for a earth-moon trajectory it might be the centre of mass of both bodies, for interplanetary mission that would probably heliocentric frame (sun defines 0 speed). For all above missions you couldn't care less about your speed relative to galaxy or CMB, you only care about your speed relative to (respectively) earth, earth-moon, sun. But you could calculate a road trip to Chicago (?) in the CMB frame and see the same results in practical fuel consumption and time it takes and all that matters. Only with very huge intermediate values.

If you intend on crashing into an asteroid then your pragmatic inertial frame is this body. There is no pragmatic (nor theoretic) difference between crashing at 10km/s in an asteroid at rest or being at rest and being smashed by an asteroid coming by 10km/s. Nothing is at absolute rest really, all is relative to another thing. That is relativity. That is easy. Since Newton.

I know that makes some people uneasy because they would be reassured to have an aether to define an "absolute background rest state of motion". Well, we where born on earth, and earth surface certainly looks like such and absolute rest state of motion, universally available. So it's quite possible humans have a certain psychological need to see such a universal reference of 0 motion. Appears this is not the way nature works. There is something like an average coherence of motions on a local patch of cosmic matter, that is roughly the same as the CMB local frame, but it is not universal (it is local and changes from place to place) and no body really cares, the Andromeda and our galaxy will collide in the same way in the same time regardless of their average common speed relative to local CMB apparent rest frame, be it 0 or 600km/s.

Quote
To elaborate, with words, not math, but hey:

The phrase "sum the instantaneous frames of rest" has the same mathematical meaning as does the phrase "add up kinetic energy in different reference frames".

All right then, now we are not happy enough with one frame of reference or two but we want to use them all. Note that, as explained above, we don't need more than one frame to have a clear and unambiguous answer to any question we might ask. You do a summation when different values of a parameter say different things. There it all says the same thing, so why would you want to sum ? How are we supposed to proceed and in what are we expected to see any difference ?

Quote
The Appendix spacecraft is said to go from 0 mph to 1 mph, in its reference frame.  It doesn't go from 671 mph to 672 mph, except as a math exercise of intellectual interest, not as a matter pf pragmatic space travel.   Besides 672 mph is not a relativistic speed, and neither is 672 km/s.

mph ???
The choice of CMB as reference frame is not pragmatic for commodity of calculations, but its results are as much pragmatic as any other one, it will tell the same times of transits and the same kinetic energy relative to spent energy. The same kinetic energy released when impacting a given asteroid (cant be more pragmatic).

Now if you want to speak of "intrinsic" kinetic energy, not of kinetic energy released by two given objects colliding, then it is nonsense. Giving a kinetic energy without saying "relative to what" is like giving a velocity without saying "relative to what" (Shawyer is doing that a lot), it has no meaning. It is like I say : the temperature in my garden is 13835. If I don't say in what units that has no meaning. If I say it's in milli celcius degrees then it makes sense. Am I to sum the temperature in all possible temperature scales (frames) to really know the temperature ?

Quote
There is not a line of mathematical reasoning which adds up kinetic energy in different, presumably aritrarily preferred, reference frames, and results inexorably in a new type of propulsion.

I don't know why I argue at length, we agree on that (I think).

Offline Rodal

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Re: EM Drive Developments
« Reply #3065 on: 11/09/2014 05:50 PM »
....
Have also to check the heat(t) at the inner surface of copper (might be higher/faster than expected) as a rise of temperature of 10░ on 100cm^3 can give as much "oomph" as 5░ on 200cm^3 or 1░ on 1000cm^3, so lack of thermal conductivity of air might not be the relevant factor to set the typical Tau. + some heat equations...
.....

Maybe if you are working on heat conduction aspects at the cavity's wall, this might help me if you have an idea of the Temp(t) of the inner skin. I know that copper is a very good thermal, conductor. The epoxy behind the (probably) much thinner copper of PCBs end plate not that much. The RF power is dissipated in the first Ám depth skin. What gives instant temperature for the air molecules hitting the inner walls ? This could be a fast alternative to volumetric humid air heating.


In this message:  http://forum.nasaspaceflight.com/index.php?topic=29276.msg1281247#msg1281247 notSoSureOfIt proposes that the circular ends of the truncated cone tested at NASA Eagleworks was made of copper only 0.002 inches thick bonded to the PCBoard.

Using the formula and material property values from http://forum.nasaspaceflight.com/index.php?topic=29276.msg1285890#msg1285890, the temperature increase is


temperature ~ Factor * t*/((1.0605*10^5)*thickness)

for thickness = 0.002 inches = 0.00005080 m and Factor = 3 (equivalent to a diameter being heated by the magnetic axial flux as 57.74% of the full diameter)

temperature = (t / 1.7958 s) deg C


the temperature increase at 2.6 sec (the pendulum half period) is 1.4 deg C, and at 30 sec is 16.7 deg C




NOTE: if the ends were made of extremely thin copper bonded on PCBoard, there are serious questions as to why would anybody do this aside from trying to maximize artificial heating of the ends



Notice assumptions:

1) All input power is converted into heat (see Greg Egan's discussion)
2) axial heat conduction away from heated zone is neglected
3) surface (at z=0) is assumed to be perfectly insulated (by the PCBoard composite material and the surrounding air)
4) diameter being heated by the magnetic axial flux assumed as 57.74% of the full diameter. For other values change "Factor" accordingly.  In the worst case (assuming that the whole diameter is being heated, which is clearly not the case) Factor = 1, and hence the calculated temperatures are 1/3 of the value calculated.
« Last Edit: 11/09/2014 07:36 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #3066 on: 11/09/2014 06:18 PM »
....
Have also to check the heat(t) at the inner surface of copper (might be higher/faster than expected) as a rise of temperature of 10░ on 100cm^3 can give as much "oomph" as 5░ on 200cm^3 or 1░ on 1000cm^3, so lack of thermal conductivity of air might not be the relevant factor to set the typical Tau. + some heat equations...
.....

Maybe if you are working on heat conduction aspects at the cavity's wall, this might help me if you have an idea of the Temp(t) of the inner skin. I know that copper is a very good thermal, conductor. The epoxy behind the (probably) much thinner copper of PCBs end plate not that much. The RF power is dissipated in the first Ám depth skin. What gives instant temperature for the air molecules hitting the inner walls ? This could be a fast alternative to volumetric humid air heating.

Recall from our discussion that NASA Eagleworks covered the interior small diameter end of the truncated cone with two Polyethylene discs, each being 1.06 inch thick, for a total thickness of 2.12 inches of polymer insulating the interior small end. 



Any such polymer disk acts as an insulator over the area where the axial magnetic field introduces a heat flux under transverse electric mode TE012. With the small end intentionally covered by the combined 2.12 inch thick polymer disks (that the NASA researchers claimed is a dielectric whose intention is to couple with the Quantum Vacuum) the only area where the magnetic field in transverse electric mode TE012 can heat is the big diameter end.

So under the 2.6 Watts of input power for TE012 experiment, instead of the heat flux being (when both the smalll and the big ends are heated):

heatFlux = (32.454 W/m^2) * Factor


using the measurement estimates from aero:

SmallDiameter = 0.1549 m
BigDiameter = 0.2793 m

when the NASA researchers covered the small end with this PE disk which they call a dielectric, the heat flux on the big end now becomes

heatFlux = (32.454 W/m^2) * Factor*(BigDiameter ^2 + SmallDiameter^2)/(BigDiameter^2)
               = (32.454 W/m^2) * Factor*(1 + (SmallDiameter/BigDiameter)^2)
               = (32.454 W/m^2) * Factor*(1 + ( 0.1549/0.2793)^2)
               = (32.454 W/m^2) * Factor*1.308

or about 31% higher heat flux on the big end



So, for thickness = 1/32 inches = 0.0007938 m and Factor = 3 (equivalent to a diameter being heated by the magnetic axial flux as 57.74% of the full diameter)

temperature = (t / 21.459 s) deg C
the temperature increase at 2.6 sec (the pendulum half period) is only 0.12 deg C, and at 30 sec is 1.40 deg C



So, for thickness = 0.02 inches = 0.0005080 m and Factor = 3 (equivalent to a diameter being heated by the magnetic axial flux as 57.74% of the full diameter)

temperature = (t / 13.734 s) deg C
the temperature increase at 2.6 sec (the pendulum half period) is only 0.19 deg C, and at 30 sec is 2.18 deg C




for thickness = 0.002 inches = 0.00005080 m and Factor = 3 (equivalent to a diameter being heated by the magnetic axial flux as 57.74% of the full diameter)

temperature = (t / 1.3734 s) deg C

the temperature increase at 2.6 sec (the pendulum half period) is 1.9 deg C, and at 30 sec is 21.8 deg C
« Last Edit: 11/09/2014 06:41 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #3067 on: 11/09/2014 07:17 PM »
Wheter unintentional or an experimental gaffe, it appears as a fact that the NASA Eagleworks researchers did everything possible to maximize internal heating of the big end:

1) They covered the exterior of the small circular end of the truncated cone with PCBoard that acted as an insulator

2) They covered the exterior of the big circular end of the truncated cone with PCBoard that acted as an insulator

3) They covered the interior of the small circular end of the truncated cone with over 2 inches thick of PE polymer insulation, which they called a "dielectric to couple with the Quantum Vacuum"

4) With the PE polymer on the interior small circular end, under transverse electric mode TE012 only the central area of the big circular end of the truncated cone was free to be heated by the axial magnetic field

5) NOTE: if the ends were made of extremely thin 0.002 inch copper bonded on PCBoard, there are serious questions as to why would anybody do this.

Frobnicat has this possible answer:  "Maybe this is the case but it is not recognized as such (artificial heating) by the experimenters, they noticed empirically that it "worked" better so they do it. And they may have an erudite guess about better quantum tunneling of vacuum plasma through thin conductors as a reason. This is the problem of a methodology that works on an unproven effect and wants to maximize the magnitude of the effect rather than having a better grasp at the experimental artefacts and a better signal/noise ratio. Or rather accounted_for/unaccounted_for ratio."

I could not find discussion of this thermal heating effect or on the extremely important thickness of the copper at the big end, on their report.

The comment from Paul March (later reproduced in the next big future blog page) that the external temperature of the EM Drive did not vary by more than 1 degree, becomes irrelevant upon examination that both ends were covered with PCBoard polymer insulation and that they did not report the internal temperature of the copper on the interior of the big end.

The transverse electric field at the interior copper surface under mode TE012 is zero and therefore there is no heating of the curved copper surface of the truncated cone.
« Last Edit: 11/09/2014 08:30 PM by Rodal »

Offline frobnicat

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Re: EM Drive Developments
« Reply #3068 on: 11/09/2014 07:34 PM »
Thank you for those inputs Rodal, this is very precious to me to see what would be the dominant factor for a warm air leak hypothesis, air heating at the surfaces of cavity or volumetric air heating (because of usual water vapor content). The later is still in the limbs quantitatively but I'm confident a decent order of magnitude can be derived from available info, yet needs more reading or finding the silver google hit.

By despair, did a few experiments with my household microwave oven (DIYers please note : closed door, not more than a few seconds empty with power on, somehow managed to put a small plastic tubing through the venting slits to see bubbling in an inverted glass water on a cup, outside the oven... no dismantling, no tinkering with door) and it appears normal air (around 50% relative humidity) is indeed heated, but this is not satisfying because of poor experimental setup, a glass bottle as a cavity was too small (too much surface to volume ratio) and "green glass" contains iron (the glass went warm quite efficiently), a bigger plastic bottle (PET) went deformed by the heat (varying volume of cavity) and went frankly hot. Can't tell if the PET was heated by the air or if PET was the coupling material. Don't know that plastic (non polar I think ?) could heat on microwave. Having no water (except water vapor of air) in those runs in a 1kW household microwave oven, the energy dissipated in what it could (and probably bounced back a lot in the magnetron's face...). An above mentioned source cited on the order of 10000 Q factor for an empty household microwave oven.

This is not experimentally convincing yet, and I complain enough of bad experimental methodologies so that I shouldn't publish, nor even talk informally about it I guess. Nevertheless it convinced me that a high enough Q microwave cavity does indeed transfer some heat to things you wouldn't usually consider as good candidates to be microwave heated because of poor absorption. I wonder how much of dissipated thermal power the bulk of dielectrics received during the experiments at eagleworks tests.

In the end, maybe both effects of surface heating and volumetric heating might have to be taken into account.

Quote from: Rodal
... if the ends were made of extremely thin copper bonded on PCBoard, there are serious questions as to why would anybody do this aside from trying to maximize artificial heating of the ends

Maybe this is the case but it is not recognized as such (artificial heating) by the experimenters, they noticed empirically that it "worked" better so they do it. And they may have an erudite guess about better quantum tunneling of vacuum plasma through thin conductors as a reason. This is the problem of a methodology that works on an unproven effect and wants to maximize the magnitude of the effect rather than having a better grasp at the experimental artefacts and a better signal/noise ratio. Or rather accounted_for/unaccounted_for ratio.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #3069 on: 11/09/2014 09:01 PM »
Yeah I'm hearing you on pseudo-chirality. The monomers aren't chiral, but the repeating units are. We're lucky both PE and PTFE feature those Carbon atoms. Else, chirality would most certainly be dead. In the end, they are chiral. I think your ideas above could be ground breaking stuff. If correct. Certainly an improvement.
I would like somebody to conduct an experiment to show whether indeed the quantum vacuum can impart momentum to a chiral polymer.   It sounds unphysical to me that this can happen (I interpret the Casimir effect as due to van der Waal forces and not to the QV). 

But, hey, I see all these theoretical papers you have uncovered, why don't they show this effect in an actual experiment?

My dear troglodytic interlocutor, and I use the term endearingly,  remember all that stuff I've been saying about seeking funding?

Lo, Shen and company seek the same grail: Continued funding.

Quote from: Shen and all
For these reasons, we hope that the quantum vacuum momentum transfer investigated in this paper can be tested experimentally in the near future.

Maybe they're not talking about their group specifically, but hey; who better to run the experioment than those who proposed the theory?

They're talking lab work somewhere.  Guys with labs like below, need not apply.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #3070 on: 11/09/2014 09:02 PM »
don't get what that reference to butchery might mean

I said it first.  The part about inertial frames.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #3071 on: 11/09/2014 09:07 PM »
...a bigger plastic bottle (PET) went deformed by the heat (varying volume of cavity) and went frankly hot. Can't tell if the PET was heated by the air or if PET was the coupling material. Don't know that plastic (non polar I think ?) could heat on microwave.....

Polyethylene terephthalate ("PET" commonly used to make bottles for carbonated drinks like Coca Cola), has oxygen-containing functional groups that make it polar hence it is heated directly by the microwave because of the polar ester groups shown in the picture below, and it should get hot (even without water):

« Last Edit: 11/09/2014 09:14 PM by Rodal »

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #3072 on: 11/09/2014 09:24 PM »
I don't know why I argue at length, we agree on that (I think).

We do agree.  I think you may not completely translate my non-scientific use of the English language, but you are so much more advanced than I am, that it is but a small matter.

Quote from: Frob
What is "your pragmatic inertial frame" depend on the dynamical system that's to be predicted but what is for sure is that you have the exact same predicted results whatever the inertial frame chosen (why "arbitrary frame") and even accelerated reference frame (done properly). There is often a "natural" frame that makes the calculations more elegant and simple and results easier to interpret, but such frame is still just an arbitrary choice to compare all velocities to the one and same, well, reference.

My "pragmatic" frame is probably exactly what you refer to as a "natural" frame.

The Appendix A spacecraft goes from Zero to 1 km/s in 200-ish days, having whatever kinetic energy it has at that time.  Using a Hall thruster, it expells a percentage of its propellant, and, like in my ICBM example from 1961 above, it will have a "paradoxical" excess of kinetic energy at the end of 200-ish days.

For the authors of the paper to engage in relativistic distractions of a comparison of velocity to the CMB, can only be interpreted as a colossal waste of everybody's time, and does not speak well as to their shallow intentions.
« Last Edit: 11/09/2014 09:44 PM by JohnFornaro »
Sometimes I just flat out don't get it.

Offline ThinkerX

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Re: EM Drive Developments
« Reply #3073 on: 11/09/2014 10:22 PM »
Ok...so if I correctly grasp the last page or two worth of posts(doubtful), the 'EM Drive' as tested by Eagleworks, is probably bogus, with the 'thrust' generated being the result of thermal heating, and this assessment may apply to Brady's design as well?  (According to Doctor Rodal and Frobnicat).

Though Mulletron, at least for the time being is still exploring Quantum options.

Offline frobnicat

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Re: EM Drive Developments
« Reply #3074 on: 11/09/2014 11:34 PM »
Ok...so if I correctly grasp the last page or two worth of posts(doubtful), the 'EM Drive' as tested by Eagleworks, is probably bogus, with the 'thrust' generated being the result of thermal heating, and this assessment may apply to Brady's design as well?  (According to Doctor Rodal and Frobnicat).

Though Mulletron, at least for the time being is still exploring Quantum options.

A lot of sceptics said it was bogus, probably thermal or so. The authors insisted that it couldn't be thermal because of the steep step of measured thrust when powering the device. They probably didn't make any attempt at quantifying that (busy as they were to improve the thruster's design and nurturing wild speculations) and relied on visual aspect only.

On more critical eye and a serious beginning of quantitative analysis (not of vacuous quantization) appears the measurement system has too much inertia to easily ascertain the steepness of the steps and that the heating (or transition to constant heating rate) might be faster than intuition would say.

Proof of thermal effect is not done, at this stage we (Rodal and I) have only working hypothesis. What is almost sure is that the authors (experimenters) haven't convincingly discarded thermal effects as the main reason of what they measured. Until we (or someone else) comes with a complete viable thermal scenario, if one is to judge the probability of the "anomalous thrust" being bogus : what is the more probable between an overlooked thermal effect and an interaction between photons and vacuum zero point energy that allows for an unlimited energy source ? ( Because, and I wont prove that again and again, whatever the theory, it is just plain impossible to have "cheap momentum" at 1N/kW and not have "free energy", cant have one and not the other. Having both would be great.)

No wait, this is reverse, we are not the paid researchers here. They should do the work of proving correctly this is not a thermal effect, then we could consider the possibility it is something less conventional. Unless they do prove this is not thermal, this is probably thermal and bogus indeed. We should not get habituated to this poor level of justifications. Because extraordinary claims...

Sorry, I don't want to be mean like that. Really, I rather have a sympathy for maverick types. But the more we dig into this and the more it shows not only bogus but deceptive. I'm still under the shock of  "initial minus final"  to show how an innocent ion thruster would violate energy conservation as much as a Q thruster would. When I see people doing such injustice to innocent little ion thrusters I just get mad.
« Last Edit: 11/09/2014 11:46 PM by frobnicat »

Online aero

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Re: EM Drive Developments
« Reply #3075 on: 11/10/2014 12:34 AM »
@Rodal - Does that level of heating give an energy balance in the end? That is, ALL of the energy goes somewhere, does it all go into heating per your calculations? Some of it must by conduction/convection go into the air to raise the pressure. And pretty quickly too, to fool the torsion balance.

Retired, working interesting problems

Offline Rodal

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Re: EM Drive Developments
« Reply #3076 on: 11/10/2014 01:30 AM »
Consider my calculations as being what happens with the EM Drive in a vacuum, without air, which is also the assumption in Greg Egan's calculations http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html.

Next, as time permits, I will show what is the origin of the initial impulse (present in the NASA Eagleworks tests of the truncated cone). 

<<The NASA researchers insisted that it couldn't be thermal because of the steep step of measured thrust when powering the device>>

I will show that that assumption is incorrect because they didn't take into account  thermoelastic inertial coupling (which is usually neglected).


Frobnicat is workiing on a longer time response due to air heating that may explain Shawyer's and the rest of the Eagleworks response.

Patience...
« Last Edit: 11/10/2014 02:18 AM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3077 on: 11/10/2014 07:15 AM »
I can see that the experimenters recognize heat contributions to the thrust plots. Look at the screen shot below. Table 2 isn't reporting 130uN of thrust for TE012, it is reporting just 55uN, after subtracting artifacts from the total 130uN peak.

They recognize da heat, which is apparent by that gentle rise over 30 seconds followed by a gentle fall over 30 seconds.

The sudden rise and sudden fall is the real thrust here.

I support all the exhaustive number crunching supporting heat as an artifact. That must also be applied equally to Cannae though. Bottom screenshot.

Conical frustums are better heaters than Cannaes are.

Especially for the Shawyer design but applicable to both designs, they've essentially built a quantum variant of a Nichols Radiometer inside with modifications, and a Crookes Radiometer outside in the test chamber, all rolled into one device.

Here's a proposed QV Nichols Radiometer experiment:
http://www.worldsci.org/pdf/abstracts/abstracts_6024.pdf
« Last Edit: 11/10/2014 08:33 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Mulletron

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Re: EM Drive Developments
« Reply #3078 on: 11/10/2014 07:38 AM »
A mathsplosion starting page 8.

http://www.astronautical.org/sites/default/files/spacetimes/spacetimes_48-6.pdf

Dr. White is trying to use the QV to thrust against the QV. I can't see how this is possible. I don't see how you can squeeze or thrust or otherwise manipulate something that you can't "touch" per se.

But I know from the Lamb Shift, Casimir effect and other phenomena that the QV does interact with matter in a random and subtle manner. So we must stop trying to mess with the QV, and instead change how it "messes" with matter.

I really think this EMdrive may be sailing the Dirac Sea!
« Last Edit: 11/10/2014 08:47 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline frobnicat

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Re: EM Drive Developments
« Reply #3079 on: 11/10/2014 09:04 AM »
I can see that the experimenters recognize heat contributions to the thrust plots. Look at the screen shot below. Table 2 isn't reporting 130uN of thrust for TE012, it is reporting just 55uN, after subtracting artifacts from the total 130uN peak.

They recognize da heat, which is apparent by that gentle rise over 30 seconds followed by a gentle fall over 30 seconds.

The sudden rise and sudden fall is the real thrust here.
.../...


If it were that sudden, why there is not the characteristic overshoot magnitude clearly visible for the calibration pulses (of similar magnitude) that are known to be "instantaneous" ?

You must see there is a huge difference between the result of rectangular force signals of calibration pulses vs thrusts pulses : the explanation is that for the later the rise is steep but not as steep. Still working on quantitative estimates but this is strongly hinting a time constant (time to asymptotically reach the plateau) that is likely much higher than anything electromagnetic in nature. Likely below 2 seconds but likely more than .1 s (analysis will tell).


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