Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2134718 times)

Offline Notsosureofit

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Thanks guys !

So I have data for everything except the mode(s), and temp size for the flight cone.

I need to use X numbers of 21, 26, and 77, respectively, for the proto, demo and flight cones to get those numbers. (w/o dielectric that is)

What that means is TBD of course.  There may be another variable involved, in or out of favor of a real effect.

Realized this morning I'd been missing something after rereading Shawer's flight paper and the Magnetron "lock" time.

Kicking myself for not recognizing a "Q multiplier circuit" (I've used enough of them)  The long lock time (time constant) is the tip-off if this is what he's doing and the results are real.  The trade off in that case is spectral purity vs the frequency stability of the oscillator since you track the cavity.

Needs only a modest *10 for the proto and demo cases.  The flight system needs *100 which is not out of the question at all.

Again, this is pure speculation on my part w/o confirmation from Shawyer, but it puts the mode back in a reasonable range.

« Last Edit: 03/01/2015 01:32 PM by Notsosureofit »

Offline zen-in

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I wonder if the following effect has been quantitatively assessed :
if a thermal displacement (again) of a part of significant mass relative to the fixation point can occur, this will change the torque seen by the balance arm around the x axis. (See attached picture for naming conventions). While the flexure bearings make for a very stiff reaction around x and y axis (compared to the natural rotation around z) no stiffness is infinite. Likewise, the Faztek beam could twist a little around the x axis. Since the distance reported in the charts is measured (along the y axis) from a plate below the beam, any increased rotation clockwise would increase this distance.

Contrary to dynamical recoil effects that needs constant acceleration to mimic sustained force, it suffices the deformation is kept at constant position (relative to fixation point) to yield an apparent long lasting force reading. As for the orientation, in this hypothesis one would have to explain a displacement of some mass to the right (relative to fixation point) to get an upward reading (corresponding to a leftward force interpretation). Expansion of frustum's copper walls alone would shift some mass to the left relative to fixation point, so would run contrary to the observed directions. Expansion of a left wall (small end) glued dielectric would go in the right direction, but Paul March reported of a try with the dielectric on the right wall (big end) and the apparent thrust haven't inverted or even reduced...

So, this is on shaky ground on orientations considerations alone, but I'd be curious to know the amount of rotation stiffness around the x axis, maybe that was discussed already ?

Side note : I'm trying to know the exact model of flexure bearings used. From this post we know that <<The Riverhawk C-flex torsion bearing's spring constant is a nominal 0.007 in-Lb/deg.>> but that doesn't add up with the vertical readings in the charts (from calibration pulses, between 0.033Ám and 0.1Ám per ÁN on vertical scale, with still unexplained disparity from chart to chart).

Nice illustrations and yes I think this effect could be happening.   Earlier I proposed this same effect to explain the negative slope in the baseline of the thrust waveform.   It appears to have a long time constant so may be from a thermally induced change in CoM.

Offline Rodal

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I wonder if the following effect has been quantitatively assessed :
if a thermal displacement (again) of a part of significant mass relative to the fixation point can occur, this will change the torque seen by the balance arm around the x axis. (See attached picture for naming conventions). While the flexure bearings make for a very stiff reaction around x and y axis (compared to the natural rotation around z) no stiffness is infinite. Likewise, the Faztek beam could twist a little around the x axis. Since the distance reported in the charts is measured (along the y axis) from a plate below the beam, any increased rotation clockwise would increase this distance.

Contrary to dynamical recoil effects that needs constant acceleration to mimic sustained force, it suffices the deformation is kept at constant position (relative to fixation point) to yield an apparent long lasting force reading. As for the orientation, in this hypothesis one would have to explain a displacement of some mass to the right (relative to fixation point) to get an upward reading (corresponding to a leftward force interpretation). Expansion of frustum's copper walls alone would shift some mass to the left relative to fixation point, so would run contrary to the observed directions. Expansion of a left wall (small end) glued dielectric would go in the right direction, but Paul March reported of a try with the dielectric on the right wall (big end) and the apparent thrust haven't inverted or even reduced...

So, this is on shaky ground on orientations considerations alone, but I'd be curious to know the amount of rotation stiffness around the x axis, maybe that was discussed already ?

Side note : I'm trying to know the exact model of flexure bearings used. From this post we know that <<The Riverhawk C-flex torsion bearing's spring constant is a nominal 0.007 in-Lb/deg.>> but that doesn't add up with the vertical readings in the charts (from calibration pulses, between 0.033Ám and 0.1Ám per ÁN on vertical scale, with still unexplained disparity from chart to chart).

My very first post on this forum was motivated by the rotation produced by the change in location of the center of mass:  http://forum.nasaspaceflight.com/index.php?topic=29276.msg1252386#msg1252386

This rotation results in nonlinear coupling of degrees of freedom.  I solved the nonlinear coupled differential equations using Mathematica.  The coupling is very small because the rotational stiffness for the motion you are considering is much stiffer than the torsional stiffness of Eagleworks torsional pendulum around the vertical axis perpendicular to the ground. (Great drawings  :), I wish I would have had those drawings to explain what I was discussing when I was posting about this).

Work out the equations, work out the numbers and see what numbers you arrive at.
« Last Edit: 03/01/2015 03:19 PM by Rodal »

Offline Rodal

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....   Earlier I proposed this same effect to explain the negative slope in the baseline of the thrust waveform.   It appears to have a long time constant so may be from a thermally induced change in CoM.

My very first post on this forum was motivated by the rotation produced by the change in location of the center of mass:  http://forum.nasaspaceflight.com/index.php?topic=29276.msg1252386#msg1252386

This rotation results in nonlinear coupling of degrees of freedom.  I solved the nonlinear coupled differential equations using Mathematica.  The coupling is very small because the rotational stiffness for the motion you are considering is much stiffer than the torsional stiffness of Eagleworks torsional pendulum around the vertical axis perpendicular to the ground.

Offline Star-Drive

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Thanks guys !

So I have data for everything except the mode(s), and temp size for the flight cone.

I need to use X numbers of 21, 26, and 77, respectively, for the proto, demo and flight cones to get those numbers. (w/o dielectric that is)

What that means is TBD of course.  There may be another variable involved, in or out of favor of a real effect.

Realized this morning I'd been missing something after rereading Shawer's flight paper and the Magnetron "lock" time.

Kicking myself for not recognizing a "Q multiplier circuit" (I've used enough of them)  The long lock time (time constant) is the tip-off if this is what he's doing and the results are real.  The trade off in that case is spectral purity vs the frequency stability of the oscillator since you track the cavity.

Needs only a modest *10 for the proto and demo cases.  The flight system needs *100 which is not out of the question at all.

Again, this is pure speculation on my part w/o confirmation from Shawyer, but it puts the mode back in a reasonable range.



Notsosureofit:

Could you describe to me how one goes about building a "Q-multiplier Circuit" for a 1.90 GHz RF amplifier circuit?  I've used the old Heathkit QF-1 Q-Multiplier for my old shortwave radio receiver back in high school, see: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_O-RX/QF-1/QF-1.pdf ,  but I've never thought to use one to enhance the Q-Factor of a microwave frustum cavity before...

Best, Paul M.
Star-Drive

Offline frobnicat

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I wonder if the following effect has been quantitatively assessed :
if a thermal displacement (again) of a part of significant mass relative to the fixation point can occur, this will change the torque seen by the balance arm around the x axis. (See attached picture for naming conventions). While the flexure bearings make for a very stiff reaction around x and y axis (compared to the natural rotation around z) no stiffness is infinite. Likewise, the Faztek beam could twist a little around the x axis. Since the distance reported in the charts is measured (along the y axis) from a plate below the beam, any increased rotation clockwise would increase this distance.

Contrary to dynamical recoil effects that needs constant acceleration to mimic sustained force, it suffices the deformation is kept at constant position (relative to fixation point) to yield an apparent long lasting force reading. As for the orientation, in this hypothesis one would have to explain a displacement of some mass to the right (relative to fixation point) to get an upward reading (corresponding to a leftward force interpretation). Expansion of frustum's copper walls alone would shift some mass to the left relative to fixation point, so would run contrary to the observed directions. Expansion of a left wall (small end) glued dielectric would go in the right direction, but Paul March reported of a try with the dielectric on the right wall (big end) and the apparent thrust haven't inverted or even reduced...

So, this is on shaky ground on orientations considerations alone, but I'd be curious to know the amount of rotation stiffness around the x axis, maybe that was discussed already ?

Side note : I'm trying to know the exact model of flexure bearings used. From this post we know that <<The Riverhawk C-flex torsion bearing's spring constant is a nominal 0.007 in-Lb/deg.>> but that doesn't add up with the vertical readings in the charts (from calibration pulses, between 0.033Ám and 0.1Ám per ÁN on vertical scale, with still unexplained disparity from chart to chart).

My very first post on this forum was motivated by the rotation produced by the change in location of the center of mass:  http://forum.nasaspaceflight.com/index.php?topic=29276.msg1252386#msg1252386

This rotation results in nonlinear coupling of degrees of freedom.  I solved the nonlinear coupled differential equations using Mathematica.  The coupling is very small because the rotational stiffness for the motion you are considering is much stiffer than the torsional stiffness of Eagleworks torsional pendulum around the vertical axis perpendicular to the ground.

Yes I recall that, but can't find the values you used, don't remember if you published or just PM to someone asking. At the moment my concern is not that much on coupling, but on absolute stiffness around the x axis (as seen from torque around x applied 10'' from the z axis). Do you know or have derived the exact flexure bearing model ? Is it a tandem of 2 C-Flex E-10 or B-20 at .0037 Lb-in/degree each as found there http://www.c-flex.com/companyproducts.pdf or a tandem of 2 RiveHawk like 5005-600 (.0035) or 5006-660 (.0037) or 5010-800 (.0036).


From this post :

Quote from: Star-Drive
The Riverhawk C-flex torsion bearing's spring constant is a nominal 0.007 in-Lb/deg., but that varies with the mass load mounted on the torque pendulum arm and selected balance point of the test article mass and its counterbalance mass on the other end of the pendulum arm relative to the torque pendulumĺs center of rotation.  Each bearing block is rated for ~25.0 Lb of vertical mass load, so we nominally restrict ourselves to a 25 pound total load limit on the torque pendulum arm to give ourselves a 100% support mass margin.

Have we anything more specific ?
For vertical mass load (ie. axial load) E-10 is rated 36.48 Lb, B-20 is 19.6 Lb (page 11 C-Flew spec sheet). From axial load indication could be A-30 or C-20, A-30 is too stiff...
Nearest fit (if 0.007 in-Lb/deg is for each) would then be C-20 : 0.0060 in-Lb/deg and 27.90 Lb axial

For RiverHawk I don't find axial load ratings, neither at here nor there.

Anyhow, even if we have 2 times .007 in-Lb/deg. that's 9.06e-2 Nm/rad (please check as I'm not used to imperial units) and a 29.1ÁN (calibration pulse) at 10'' from z axis is 7.39e-6 Nm, so we should have 8.16e-5 rad, that is 20.7 Ám deviation (at 10'' from z axis, LDS is a bit further so it should be even a bit more).

Yet we see on the charts that the calibration pulses give between 1 to 2.5 Ám deviation on the vertical scale. We don't know why this should be varying from chart to chart, and there is one order of magnitude difference with the given stiffness. So maybe the indicated vertical scale is irrelevant... but then it becomes difficult to model the system. Looks like the flexure bearing are stiffer than 0.007 in-Lb/deg. (around z).

Offline Rodal

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I wonder if the following effect has been quantitatively assessed :
if a thermal displacement (again) of a part of significant mass relative to the fixation point can occur, this will change the torque seen by the balance arm around the x axis. (See attached picture for naming conventions). While the flexure bearings make for a very stiff reaction around x and y axis (compared to the natural rotation around z) no stiffness is infinite. Likewise, the Faztek beam could twist a little around the x axis. Since the distance reported in the charts is measured (along the y axis) from a plate below the beam, any increased rotation clockwise would increase this distance.

Contrary to dynamical recoil effects that needs constant acceleration to mimic sustained force, it suffices the deformation is kept at constant position (relative to fixation point) to yield an apparent long lasting force reading. As for the orientation, in this hypothesis one would have to explain a displacement of some mass to the right (relative to fixation point) to get an upward reading (corresponding to a leftward force interpretation). Expansion of frustum's copper walls alone would shift some mass to the left relative to fixation point, so would run contrary to the observed directions. Expansion of a left wall (small end) glued dielectric would go in the right direction, but Paul March reported of a try with the dielectric on the right wall (big end) and the apparent thrust haven't inverted or even reduced...

So, this is on shaky ground on orientations considerations alone, but I'd be curious to know the amount of rotation stiffness around the x axis, maybe that was discussed already ?

Side note : I'm trying to know the exact model of flexure bearings used. From this post we know that <<The Riverhawk C-flex torsion bearing's spring constant is a nominal 0.007 in-Lb/deg.>> but that doesn't add up with the vertical readings in the charts (from calibration pulses, between 0.033Ám and 0.1Ám per ÁN on vertical scale, with still unexplained disparity from chart to chart).

My very first post on this forum was motivated by the rotation produced by the change in location of the center of mass:  http://forum.nasaspaceflight.com/index.php?topic=29276.msg1252386#msg1252386

This rotation results in nonlinear coupling of degrees of freedom.  I solved the nonlinear coupled differential equations using Mathematica.  The coupling is very small because the rotational stiffness for the motion you are considering is much stiffer than the torsional stiffness of Eagleworks torsional pendulum around the vertical axis perpendicular to the ground.

Yes I recall that, but can't find the values you used, don't remember if you published or just PM to someone asking. At the moment my concern is not that much on coupling, but on absolute stiffness around the x axis (as seen from torque around x applied 10'' from the z axis). Do you know or have derived the exact flexure bearing model ? Is it a tandem of 2 C-Flex E-10 or B-20 at .0037 Lb-in/degree each as found there http://www.c-flex.com/companyproducts.pdf or a tandem of 2 RiveHawk like 5005-600 (.0035) or 5006-660 (.0037) or 5010-800 (.0036).


From this post :

Quote from: Star-Drive
The Riverhawk C-flex torsion bearing's spring constant is a nominal 0.007 in-Lb/deg., but that varies with the mass load mounted on the torque pendulum arm and selected balance point of the test article mass and its counterbalance mass on the other end of the pendulum arm relative to the torque pendulumĺs center of rotation.  Each bearing block is rated for ~25.0 Lb of vertical mass load, so we nominally restrict ourselves to a 25 pound total load limit on the torque pendulum arm to give ourselves a 100% support mass margin.

Have we anything more specific ?
For vertical mass load (ie. axial load) E-10 is rated 36.48 Lb, B-20 is 19.6 Lb (page 11 C-Flew spec sheet). From axial load indication could be A-30 or C-20, A-30 is too stiff...
Nearest fit (if 0.007 in-Lb/deg is for each) would then be C-20 : 0.0060 in-Lb/deg and 27.90 Lb axial

For RiverHawk I don't find axial load ratings, neither at here nor there.

Anyhow, even if we have 2 times .007 in-Lb/deg. that's 9.06e-2 Nm/rad (please check as I'm not used to imperial units) and a 29.1ÁN (calibration pulse) at 10'' from z axis is 7.39e-6 Nm, so we should have 8.16e-5 rad, that is 20.7 Ám deviation (at 10'' from z axis, LDS is a bit further so it should be even a bit more).

Yet we see on the charts that the calibration pulses give between 1 to 2.5 Ám deviation on the vertical scale. We don't know why this should be varying from chart to chart, and there is one order of magnitude difference with the given stiffness. So maybe the indicated vertical scale is irrelevant... but then it becomes difficult to model the system. Looks like the flexure bearing are stiffer than 0.007 in-Lb/deg. (around z).
Based on my interpretation of early discussions with Paul March in Thread 1, I assumed that the compliance for rotation around your x axis was due to the aluminum beams and that the RiverHawk bearings provided an effective clamp condition for rotation around the x axis. 

My recollection (I have not gone back and checked this) is that March said that there were two RiverHawk bearings providing a clamped condition (for rotations around your x axis and for rotations around your y axis).

(Any fault with this assumption rests squarely on my own shoulders as the initial exchanges with Paul March were very unfortunately brought to an abrupt end due to disruptive posters in Thread 1 who wanted to argue with Paul March about General Relativity theory, Mach Effects, Quantum Vacuum, and what Chris described as "stupid posts" instead of obtaining engineering data and instead of performing any calculations.  Paul March withdrew shortly thereafter for a long period of time, so I relied on my own interpretations of the initial few posts by March and on my own assumptions).

« Last Edit: 03/01/2015 04:36 PM by Rodal »

Offline Notsosureofit

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Thanks guys !

So I have data for everything except the mode(s), and temp size for the flight cone.

I need to use X numbers of 21, 26, and 77, respectively, for the proto, demo and flight cones to get those numbers. (w/o dielectric that is)

What that means is TBD of course.  There may be another variable involved, in or out of favor of a real effect.

Realized this morning I'd been missing something after rereading Shawer's flight paper and the Magnetron "lock" time.

Kicking myself for not recognizing a "Q multiplier circuit" (I've used enough of them)  The long lock time (time constant) is the tip-off if this is what he's doing and the results are real.  The trade off in that case is spectral purity vs the frequency stability of the oscillator since you track the cavity.

Needs only a modest *10 for the proto and demo cases.  The flight system needs *100 which is not out of the question at all.

Again, this is pure speculation on my part w/o confirmation from Shawyer, but it puts the mode back in a reasonable range.



Notsosureofit:

Could you describe to me how one goes about building a "Q-multiplier Circuit" for a 1.90 GHz RF amplifier circuit?  I've used the old Heathkit QF-1 Q-Multiplier for my old shortwave radio receiver back in high school, see: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_O-RX/QF-1/QF-1.pdf ,  but I've never thought to use one to enhance the Q-Factor of a microwave frustum cavity before...

Best, Paul M.

"Q-multiplier" is the Heath term for adding feedback, short of oscillation, to an IF amplifier to narrow the bandwidth
and enhance its "Q" as a filter.  (had one on an HRO receiver in the 50's.  HRO long gone but the Q-Multiplier is still in the pile somewhere)

In the case of greater feed back you get an oscillator. (had a 220MHz re-entrant cavity oscillator at that time)

The right feedback loop will improve the phase coherence of the oscillation and the "circuit Q".  You pay for this with an increased time constant and are limited by the (thermal ?) drift rate of the cavity.  The "flight" cavity might be heavily built for that reason ?

Hopefully there is a radar guy (like Shawyer) on tap that could give a better explanation. (I'm pulling this out of memories of my misspent youth...)

I was trying to remember something about radar systems (Russian ?) that had a dielectric resonator suspended in a microwave cavity.............


Offline DIYFAN

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Dr. Rodal & Crew:

The Eagleworks team has already build a 6061 aluminum frustum cavity with 1/4" thick walls and O-ring end caps meant to hold a 1 Bar pressure differential with internal nickel/copper/silver/gold plating system on all interior surfaces with plating thickness of 10-to-15 microns for the first three layers and 0.5 microns for exposed to the RF gold layer.  Sadly the gold layer was just as thick as the rest of the plated layers and textured as well, so as far as the applied ~2.0 GHz RF was concerned it was only interacting with the rough gold layer.  This had the effect of cutting the resonant Q-factor for this aluminum frustum by almost a factor of three over our copper frustum for the resonances of interest. 

At the same time we also tried using a smaller volume, higher-K (e-r=~40) ceramic dielectric resonator discs in the Al cavity mounted at its small OD end, while driving it at its TE011 mode if memory serves.  Bottom line was that this configuration was a total bust in regards to thrust production in our torque pendulum system running at this resonant mode.  This aluminum frustum design also turned out to be ~4X times the mass of the thin walled copper cavity even while using lower density aluminum for its construction.  This exercise was a tribute to the fact that one should never ASSUME that you know what you are doing until proven otherwise!  And oh yes, and only try one variation in the design at a time or one will get lost, fast!

Best, Paul M.

Dr. March,

I'm a big fan of what you and Eagleworks are doing, particularly in the face of tremendous skepticism.  It takes some truly courageous scientists to do what you are doing.  We all hope for an eventual proof or nullification of this effect.

There has been some discussion here about Dr. Aquino's theory of how to amplify the effect (simply search this thread for "aquino").  I hope you don't mind me asking if you or others at Eagleworks have tested this theory.  Specifically, have you tried using a metglas coating or sheet for the big flat end of the frustum?  Alternatively, have you tried using an iron coating or sheet for the big flat end of the frustum?  (The iron suggestion was proposed by a forum member as an alternative to metglas, albeit an inferior alternative.)  Are either of these feasible to attempt in your experimental setup?  Do you think it is worth the time to test Dr. Aquino's theory or do you have other higher priority tasks at hand?  Dr. Rodal used Dr. Aquino's conjecture to predict a 20-50 times amplification of the effect based on an extrapolation of the permeability characteristics of metglas, specifically metglas 2714A.  Metglas 2714A might be hard to procure, but iron certainly would not be.  It might also be quite easy to procure a metglas brazing foil, which could be fitted to the interior of the large flat plate.
« Last Edit: 03/01/2015 10:38 PM by DIYFAN »

Offline Rodal

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See this post:  http://forum.nasaspaceflight.com/index.php?topic=36313.msg1328595#msg1328595
regarding Aquino's conjecture, links to his paper and to published material constant values for Metglas.

Aquino, when advocating the use of Metglas 2714A failed to take into account that its ultra-high magnetic permeability which he quotes in the paper (apparently for his calculations) as μ=1,000,000 occurs at very low frequencies and that its magnetic permeability decreases significantly at higher frequencies.   I extrapolated published data to come up with a more reasonable estimate (if Aquino's conjecture would be correct).
« Last Edit: 03/01/2015 07:12 PM by Rodal »

Offline Star-Drive

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DIYFAN:

Once the test series we are working on is finished, I will suggest to Dr. White that we try the use of the more readily available NiFeCo mu-metal from McMaster-Carr (See: http://www.mcmaster.com/#mu-metal-foil/=w4hfa3 ) for such a test.  However I think we will have to copper plate the side of the mu-metal facing the interior of the cavity with about 10 microns of copper or silver to keep this large OD end-cap from greatly reducing the Q-Factor of the copper frustum.  Mu-metal resistivity is much higher than copper...

Best,  Paul M.
Star-Drive

Offline frobnicat

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Dr. March,

I'm trying to model various aspects of the whole system to put upper bounds on thermal effects, and possibly also reconstruct the thrust(t) original signal from the distance(t) given in the charts. It would be a nice boost to this (amateur level) effort if you could confirm either :
- That the flexure bearings have a stiffness of 0.007 in-Lb/deg ? Each ? Both together ? Do you know the exact model reference ?
- That the vertical scale in the charts (indicated in Ám, around 500) are relevant or not relevant.

I ask this question because I find a contradiction between the stiffness around the vertical axis and the recorded deviation from the 30ÁN calibration pulses (at .007 in-Lb/deg the deviation of the linear displacement sensor would be above 40Ám, at .014 in-Lb/deg still above 20Ám). The readings amount for between 1 to 2.5 Ám for the 30ÁN calibration pulses. So I'm stuck.

While I'm at it : is the plane in which the arm rotates kept as horizontal as possible (ie the axis of rotation as vertical as possible) or is there a small slope voluntarily introduced leading to some pendulum effect against g (for stabilisation or tuning purpose) ? That could explain the varying deviation (in Ám) for the same calibration pulses thrusts. Also wondered if this is what was implied in this post :
Quote from: Star-Drive
...
These thermally induced actions to the left requires the torque pendulum's arm to move to the right to maintain the balance of the torque pendulum's arm in the lab's 1.0 gee gravity field, since we also use the Earth's g-field to help null the pendulum's movements.
...

Thanks

Offline Rodal

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DIYFAN:

Once the test series we are working on is finished, I will suggest to Dr. White that we try the use of the more readily available NiFeCo mu-metal from McMaster-Carr (See: http://www.mcmaster.com/#mu-metal-foil/=w4hfa3 ) for such a test.  However I think we will have to copper plate the side of the mu-metal facing the interior of the cavity with about 10 microns of copper or silver to keep this large OD end-cap from greatly reducing the Q-Factor of the copper frustum.  Mu-metal resistivity is much higher than copper...

Best,  Paul M.
I couldn't find magnetic permeability values for mu metal close to the GHz range, except the frequent warning (also included in the Wikipedia article) <<The high permeability makes mu-metal useful for shielding against static or low-frequency magnetic fields>> (bold added for emphasis).

I wonder what is the relative magnetic permeability of mu metal in the GHz range, and how effective it will be for the purposes described by Aquino.
« Last Edit: 03/01/2015 09:46 PM by Rodal »

Offline Flyby

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Small update on the image correcting..

I decided to take a different approach as I clearly need to have a more methodical approach to be convincing. :-\
Tbh, as mentioned, something about the tilt correction didn't match up, so I took a different angle for handeling the problem...

What remains are the camera distortions:  the barrel distortion and the tilt-distortion.

BARREL DISTORTION
The barrel distortion is camera lens dependent , and as we do not know the type of camera and lens used, a general correction on the barrel distortion has been performed, using pincushion lens distortion filter for photoshop.
The pincushion distortion is the opposite of the barrel distortion and is able to cancel out the original distortion. Notice on how the mortar line on the back wall is curved on the original picture and straightened on the corrected one...
A zoom lens will tend to cause pincushion distortion, a wide angle lens tends to cause barrel distortion...

The effect is that the height of the corrected cone will be a tiny bit less then on the non corrected one

TILT DISTORTION
To understand - and illustrate - what's happening with the tilt distortion, I've recreated an approximation of the scene in my 3Dsoftware.
I exaggerated the effect a bit to make it clearly visible what's happening :
Due to the tilting of the camera, the normally vertical lines no longer converge at an infinite distance (= apparent perpendicular), but at a point much closer to the horizon.
What makes it very interesting is that the vertical (red) lines on the back wall and the vertical (yellow) lines on the cylinder converge to the same point.
Also interesting to know is that a wide angle lens (fe 28mm) causes more distortion then a normal lens (50mm)

Similar to the test file, I've used the vertical brick lines of the wall to find the converging point in the photograph...



When you apply that knowledge to the barrel corrected image and you imagine the cone to be a cylinder, you can find all measures in a correct relation with each other...

Sadly, it's getting very, very late again... so I didn't have time yet to put it all in proportional numbers yet.
More tomorrow...hopefully...

But I think it already demonstrates that you should not underestimate/neglect the amount of distortion caused by the tilting of the camera...




BTW.. curiosity killed the cat...An interview with Paul March...
http://beforeitsnews.com/science-and-technology/2014/10/paul-march-reactionless-drive-interview-2726212.html

 
« Last Edit: 03/01/2015 10:48 PM by Flyby »

Offline Rodal

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Here are my calculations, from the exact solution, for the mode shape presently being tested by NASA Eagleworks, and for which they obtained thermal IR camera imaging.  I show the resultant of both components of the magnetic field, in the polar (theta) (perpendicular to the cone walls) and azimuthal (phi) (circumferential)  directions of the truncated frustum. The resultant is the square root of the sum of the squares of each component.  These results are for a truncated cone without dielectric.  The frequency for the mode TM221 mode shape (without the dielectric) is 2.00709 GHz.

I show density plots (also called intensity plots) with two different color schemes (plum colors gradient and a blue-white-yellow-orange-red gradient) for comparison. The relative scale numbers associated with the image are correct but their magnitude is not (I have to multiply the numbers by a scale factor based on integrating the electromagnetic field to equal the applied power).  I also show the NASA calculations done with Finite Element (COMSOL) analysis and the thermal IR camera measurements for comparison.

On this cross-section, TM221, TM222 and TM223, etc, look practically identical, except for different intensity magnitude for the higher frequency modes with TM22p where p>1.



« Last Edit: 03/02/2015 01:31 AM by Rodal »

Offline Rodal

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You may notice that I labeled the mode TM22 instead of TM21.  This is intentional.  When using a numerical method like the Finite Element Method (used by NASA Eagleworks for labeling the mode as TM21), the analyst is not given the mode shape number by the (COMSOL) solver.  The analyst has to resort to ascertaining what mode shape it is by inspecting the figure (which is not trivial to do).  In this case, this is the first TM2n appearing, and therefore it is understandable that the analyst may interpret "n" as n=1.  However, one of the advantages of an exact solution (which is what I am using) is that the exact values of m, n, p are given by the solution.  One does not have to resort to visual inspection to ascertain them.  In this case, n=2 (instead of n=1) because the solution for the eigenvalue problem for the Legendre function shows that there is a first root (corresponding to n=1) occurring at a value of the integer 1 (exactly) in the abscissa (images shown below for first root at the abscissa value of 1, and below it is the image for the next few roots, occurring at irrational numbers).  This eigenvalue at n=1 corresponds to a value of zero of the Legendre function, therefore the TM21 mode is cut-off.  That's why TM21 does not appear and that's why TM22 is the mode with the lowest n value for TM2n.
« Last Edit: 03/02/2015 01:34 AM by Rodal »

Offline Rodal

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The density (or intensity) plot shown above for mode TM221 is, as explained above, the magnetic field resultant of the polar and azimuthal compoments magnetic field components.

Here I show the polar (theta) (perpendicular direction to the cone walls) and the azimuthal (phi) (circumferential) components of the magnetic field at the Big Base, separately, as contour plots.

You may notice that n=2 based on the fact that the polar (theta) component has two half-waves patterns fitting in the diameter.  Equivalently, there are 2 full-wave patterns of the azimuthal component fitting in the diameter.  These are alternative ways to determine the proper value of n.

But after looking at a lot of results from the exact solution for different modes, there is no doubt that the best way is to ascertain the proper values of the quantum numbers m, n and p from the eigenvalues, since there is no human judgement involved in doing so.
« Last Edit: 03/02/2015 12:32 AM by Rodal »

Offline Rodal

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This is the Electric Field in the radial direction (plane at azimuthal angle phi=0).  We see that the electric field in the radial direction is concentrated at the Big End.  Notice that the ends are spherical (instead of flat) because the exact solution uses spherical Bessel functions and assumes wave propagation occurs as spherical waves .

No wonder that the screws are being damaged by the electric field !
« Last Edit: 03/02/2015 12:38 AM by Rodal »

Offline Star-Drive

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Dr. March,

I'm trying to model various aspects of the whole system to put upper bounds on thermal effects, and possibly also reconstruct the thrust(t) original signal from the distance(t) given in the charts. It would be a nice boost to this (amateur level) effort if you could confirm either :
- That the flexure bearings have a stiffness of 0.007 in-Lb/deg ? Each ? Both together ? Do you know the exact model reference ?
- That the vertical scale in the charts (indicated in Ám, around 500) are relevant or not relevant.

I ask this question because I find a contradiction between the stiffness around the vertical axis and the recorded deviation from the 30ÁN calibration pulses (at .007 in-Lb/deg the deviation of the linear displacement sensor would be above 40Ám, at .014 in-Lb/deg still above 20Ám). The readings amount for between 1 to 2.5 Ám for the 30ÁN calibration pulses. So I'm stuck.

While I'm at it : is the plane in which the arm rotates kept as horizontal as possible (ie the axis of rotation as vertical as possible) or is there a small slope voluntarily introduced leading to some pendulum effect against g (for stabilisation or tuning purpose) ? That could explain the varying deviation (in Ám) for the same calibration pulses thrusts. Also wondered if this is what was implied in this post :
Quote from: Star-Drive
...
These thermally induced actions to the left requires the torque pendulum's arm to move to the right to maintain the balance of the torque pendulum's arm in the lab's 1.0 gee gravity field, since we also use the Earth's g-field to help null the pendulum's movements.
...

Thanks


Frobnicat:

To answer your question:

" - That the flexure bearings have a stiffness of 0.007 in-Lb/deg ? Each ? Both together ? Do you know the exact model reference?"

The two torsion bearings used in or torque pendulum are supposed to have a stiffness of 0.007 in-Lb/deg, +/-10% and is made by the Riverhawk Co. in New York USA.  As to their model number find the data sheet for same attached. 

"- That the vertical scale in the charts (indicated in Ám, around 500) are relevant or not relevant."

The Philtec D63 fiber-optic displacement sensor measures distance from its target mirror in microns, so the numbers on the left hand side of the force plots measure the distance from the end of the fiber-optic laser head to its mirror target mounted on the torque pendulum arm.  The data sheet for same is attached.

"While I'm at it : is the plane in which the arm rotates kept as horizontal as possible (ie the axis of rotation as vertical as possible) or is there a small slope voluntarily introduced leading to some pendulum effect against g (for stabilization or tuning purpose)?"

The design of our Torque pendulum follows what JPL and Busek Co did at their respective facility, see attached report from Busek.  We found that if we tried to keep the arm completely horizontal though that the pendulum's neutral point would wonder erratically and make alignments near impossible.  So yes I balance the pendulum arm so there is always a slight tilt in it, however this tilt angle magnitude is not controlled as well as it probably should.

Best, Paul M.

Offline aero

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@Mulletron

I made some cylindrical cavity runs. Meep is still saying what it has been saying to me for the past month. Attached find a graphic of the cavity. The dimensions are given on the F/P charts. Maximum thrust/power, in meep micro-Newtons/Watt are:

Magnetic source - 4,841
Electric source  - 11,952

Note that I used a large gap of 0.008 times height in order to keep the run times down. ( About half-hour per data point as is.) Anyway, I didn't want the numbers to be excessively astounding as they might be at reasonable small gap sizes.
Retired, working interesting problems

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