Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2101909 times)

Online Rodal

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Great !

Next need to solve for the expression (f0^2 - f2^2) where (f0 => L1+L2=0 and f2 =>L1+L2=L ??)

Hmmm, let me think about that for a second.  What we want to do is isolate the (p*pi/L)^2 term so it will cancel out leaving the Doppler shifts in the accelerated frame. ie. (f0^2 - f2^2)

There are 3 terms involving p, two of them are proportional to p^2 and the third one is proportional to p^4

Two of the terms multiplying p only involve L1/c1 and L2/c2, another term (the negative second p^2 term, inside the second SquareRoot) involves a lot of stuff..


Sorry, I don't understand what you wrote...  What is what f0 and f2 ?

If you would like me to calculate a Limit of an expression, as a variable goes to a certain value, I can do that very precisely.  I can also do a perturbation analysis if you want to pursue a series expansion as a parameter goes to zero...
« Last Edit: 03/05/2015 11:35 PM by Rodal »

Online Rodal

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I don't understand how to go from here for the cylindrical RF cavity with only one medium:

f = (c/(2*Pi))*((X/R)^2+((p*Pi)/L)^2)^.5

to here:

df = (1/(2*f))*(c/(2*Pi))^2*X^2*((1/Rs^2)-(1/Rb^2))

What is df ?

How do you rotate the dispersion relation of the cavity into a Doppler frame to get the Doppler shifts ?, looking at the dispersion curve intersections of constant wave number instead of constant frequency.



Where do the terms Rs^2 and Rb^2 come from?
« Last Edit: 03/06/2015 12:04 AM by Rodal »

Offline Notsosureofit

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@ RODAL

I'm struggling w/ the best way to explain it.  We want to get the expression (f0^2 - f2^2) such that the frequencies

f0 and f2 are evaluated at the two ends of the cavity at the same wavenumber.  They are the frequencies (energies) that would appear at the ends of the cavity if it were accelerated to the point that the dispersion between the ends were to disappear.

Yes, dispersion curve intersections at constant k.

No by df I just mean f1-f2 ie del f

From f^2 evaluations at the ends  (ie (f1^2-f2^2) = del f * 2f0  etc.

[Excuse the quick..I'm being otherwise distracted at the moment]
« Last Edit: 03/06/2015 12:14 AM by Notsosureofit »

Online Rodal

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@ RODAL

I'm struggling w/ the best way to explain it.  We want to get the expression (f0^2 - f2^2) such that the frequencies

f0 and f2 are evaluated at the two ends of the cavity at the same wavenumber.  They are the frequencies (energies) that would appear at the ends of the cavity if it were accelerated to the point that the dispersion between the ends were to disappear.

Yes, dispersion curve intersections at constant k.

No by df I just mean f1-f2 ie del f

From f^2 evaluations at the ends  (ie (f1^2-f2^2) = del f * 2f0  etc.

[Excuse the quick..I'm being otherwise distracted at the moment]

This time, instead of purely geometrical terms for the truncated cone with only one medium like

(b^2)*((1/Rs)^2 - (1/Rb)^2)

one gets terms due to the different speed of light in mediums 1 and 2 for example

(b^2)*((L1/c1)^2 -(L2/c2)^2)


=> this is quite pedagogical to understand your point, and Mulletron's point that a cylindrical cavity with two different dielectric mediums maybe as or more effective than a truncated cone with only one medium
« Last Edit: 03/06/2015 12:29 AM by Rodal »

Offline frobnicat

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Follow up on the Z tilted component of the pendulum as used at Eagleworks for the EM drive reported experiments.

For recall we have the following situation :


The tilt in this illustration is obviously grossly exaggerated. The only quantitative estimation I have from Star-Drive is that the platform deviates from horizontal, downward toward X- (as illustrated), for ~ .25 a bubble of a 24'' level. It depends on the level, I have a 60 cm level and .25 bubble corresponds to 12mm raise of one end, that is 2% slope or about 1.15. Anyway, it can't be 10 and it can't be .1 so I will assume 1 as an order of magnitude first estimate of this angle I call theta.

Assuming Z is a perfect axis without stiffness (we know this is not true, there is a restoring torque of 2*0.007 Lb-in/degree in the flexure bearings) a tilted pendulum like that with a CoM (centre of mass) for the rotating assembly that is lowered by the tilt (that is the case, the CoM is toward X-) is stable and is strictly equivalent to a vertical hanging pendulum with a reduced gravity of g sin(theta). The problem can therefore be studied in the plane XY as if there was a gravity toward X-. It will also be equivalent when I will add the restoring torque component of the flexure bearings but at the moment I leave that aside and will treat it as a separate angular spring constant on top of a perfect tilted Z axis pendulum. The following drawing from this post illustrates the principle.

Too big picture, still struggling to insert a new attached picture inside the body... please follow this link if needed.


Why is it so important ? Any shift along Y (tangential) of the CoM of the test article relative to its point of attach on the arm will change the rest equilibrium position. This change is "amplified" by the proximity of the global CoM (whole rotating assembly) relative to axis Z : the angle of deviation of rest angular position is actually (a bit) more than the angle of the test article's CoM shift as seen from the axis. A thermal shift of 5m would record more than 5m on the LDS. And given the orientations, a shift of CoM toward Y-, for instance an inward buckling of the big end cap, but also the global expansion along the length of the frustum, has an effect in reverse of what everyone thought : it will actually raise the LDS readings.

In the attached schematics below, approximately to scale (apart from deviations greatly exaggerated), green dot represents the CoM A of electronic stack and whole Faztek beam, yellow dot represents the CoM B of test article, black cross represents the CoM AB of the whole rotating assembly, it is the barycentre of the weighted green dot and yellow dot positions.

1. Initial stable equilibrium rest position, note that we have a hanging pendulum in a reduced gravity of g sin(theta). From latest weight and positions values where I lack only the mass of dielectric (small end, should have asked, I assumed 1kg, anyone ?) the CoM AB is 6cm below the axis.

2. A thermal expansion of test article would shift CoM B to the right (exaggerated here). As a result the global CoM AB will be shifted to the right, the torque will be clockwise.

3. The rest equilibrium position needs CoM AB to be at the vertical ( as defined by vector g projection on XY, that is the vector a of magnitude g sin(theta) ) below the axis, so that the Force vector F = M g sin(theta) don't have torque relative to the rotation, M being the total mass of assembly. Assuming theta=1 as a first guess, g sin(theta) is worth 0.17 m/s (0.017 g) and F = 1.95 N.

Obviously (but I prefer to state it explicitly) this is not 2. instant final shift  then 3. new rest equilibrium. The thermal shift would occur gradually and the equilibrium position would follow gradually. Dynamic aspects should be studied too, but 1. and 3. are two valid static situations (1. before heating, 3. either just after heating stops or at new thermal equilibrium under power load and temperature has reached a plateau).

Now if we compare the equivalent stiffness ( restoring torque per angular deviation ratio in Nm/rad ) of this "tilted hanging pendulum" component with the stiffness of the flexure bearings :

(F application point 6cm from axis, linearised .06m/rad * 1.95N = 0.117 Nm/rad)
Tilted hanging pendulum : 0.117 Nm/rad (from a guesstimate of tilt 1)
Two flexure bearings 0.007 Lb-in/degree each : 0.0906 Nm/rad

The tilted hanging pendulum component is in the same ballpark as the flexure bearings. The flexure bearings can "dilute" the impact of a test article's CoM thermal shift on the sustained displacement of rest angular equilibrium but only to a limited ratio. Even if m displacements of LDS readings relative to m shifts of tests article CoM is not 1 to 1, it may very well be  1 to 2 or 1 to 3. And those effects are direct, it's not like the sustained deviations in readings are to be accounted by a constant second derivative of CoM's position as would be the case with pure recoil effects. No longer. Now, every single sustained 1m deviation of readings might be explained by a sustained expansion (ie a body at or near new thermal equilibrium) displacement of a few m at most.

Now, if only we could explain the discrepancies of the vertical axis readings of between 1m to 2.5m relative to the calibration pulses of 29.1N... Could anyone do detailed check and see a blunder or a flaw ?
« Last Edit: 03/06/2015 12:50 AM by frobnicat »

Offline Notsosureofit

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@ RODAL

I'm struggling w/ the best way to explain it.  We want to get the expression (f0^2 - f2^2) such that the frequencies

f0 and f2 are evaluated at the two ends of the cavity at the same wavenumber.  They are the frequencies (energies) that would appear at the ends of the cavity if it were accelerated to the point that the dispersion between the ends were to disappear.

Yes, dispersion curve intersections at constant k.

No by df I just mean f1-f2 ie del f

From f^2 evaluations at the ends  (ie (f1^2-f2^2) = del f * 2f0  etc.

[Excuse the quick..I'm being otherwise distracted at the moment]

This time, instead of purely geometrical terms for the truncated cone with only one medium like

(b^2)*((1/Rs)^2 - (1/Rb)^2)

one gets terms due to the different speed of light in mediums 1 and 2 for example

(b^2)*((L1/c1)^2 -(L2/c2)^2)


=> this is quite pedagogical to understand your point, and Mulletron's point that a cylindrical cavity with two different dielectric mediums maybe as or more effective than a truncated cone with only one medium

Yes, and the accelerated frame of reference is just an easy way to think about the thrust/photon; T = h*[del f]/L   It cancels out of the derivation.

Offline aero

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Quote
this is quite pedagogical to understand your point, and Mulletron's point that a cylindrical cavity with two different dielectric mediums maybe as or more effective than a truncated cone with only one medium

You can add meep to that camp. Or at least for all indications you can but I should make some controlled runs to confirm it. If I ran a truncated cone and a cylinder, what frequency and cylindrical dimensions would I use in order that it be a fair comparison to the truncated cone? Dielectric constant? Or, if you prefer, what cylinder and cone dimensions are consistent? Same resonant frequency and mode or same "size" "volume" but since we're addressing a space thruster, maybe integrated structural mass? Cylinders tend to be smaller and simpler.
Retired, working interesting problems

Online Rodal

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Quote
this is quite pedagogical to understand your point, and Mulletron's point that a cylindrical cavity with two different dielectric mediums maybe as or more effective than a truncated cone with only one medium

You can add meep to that camp. Or at least for all indications you can but I should make some controlled runs to confirm it. If I ran a truncated cone and a cylinder, what frequency and cylindrical dimensions would I use in order that it be a fair comparison to the truncated cone? Dielectric constant? Or, if you prefer, what cylinder and cone dimensions are consistent? Same resonant frequency and mode or same "size" "volume" but since we're addressing a space thruster, maybe integrated structural mass? Cylinders tend to be smaller and simpler.

The best thing (if you have not already done so) is to run exactly the same cylinder geometry with at least two runs: one run with a single medium and another run with two mediums inside it.

What force do you get when you run the cylinder with only one medium (for example just vacuum) in MEEP  as compared to the same cylinder diameter and length with two mediums inside it (vacuum at one end and a dielectric at the other end)?
« Last Edit: 03/06/2015 01:52 AM by Rodal »

Offline Notsosureofit

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@ RODAL

Heading off, but I thought I should clarify that the f vs k curve I've been using has the third axis (into the paper) where k is an "instantaneous" function of x from 0 to L, evaluated at 0 and L  for f1, f2, which are (hopefully) the extremes.


Offline Star-Drive

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@ Rodal :
See attached picture to share my mental image. Tilt over-exaggerated for illustration.

Grey : solid rotating assembly (no deformation implied)
Orange/brown : fixed assembly (no deformation implied)
Blue : the ground slab of the vacuum chamber (no deformation implied)

For now, assume a perfect axis of rotation around Z : only one degree of freedom of Grey relative to Orange, the "official" rotation around Z, no compliance implied, Grey kept in the XY plane, plane has same tilt as Orange (XY parallel to Orange platform).

@Star-Drive
Can you confirm this is a correct way to understand that there is a tilt in the axis of rotation ?



One aspect of this tilt in the axis of rotation that hasn't been discussed is the requirement for imbalance.   The difference in moments on either side of the beam only has to be very slight for it to always come to rest at the same location +/- a micron or two.

Yes, a difference in centre of mass can make long lasting difference in position. The following statement tries to summarize rigorously :
Statement A : Any shift in centre of mass of a part (relative to fixation to the balance arm) along a direction orthogonal to a compliant (not infinite stiffness) axis that is not strictly vertical can induce a change in angular rest position around said compliant axis.

This can be quite important as a (thermal) longitudinal (Y+ or Y-) shift in CoM of the frustum assembly would be orthogonal to axis Z, but so long as this most compliant by far axis Z (the natural axis of the pendulum) was believed to be strictly vertical there would be no change in angular rest position of the arm (around Z). Only transient angular positions shifts could be induced by such thermal CoM shifts, the arm position (around Z) would be quickly enough restored to unmodified rest position (return to baseline) by the spring restoring torque of flexure bearings, and then time of ~45s during which a sustained displacement where recorded could be used as an effective argument that this couldn't be due to thermal expansions alone.

Note that now that the Z axis is no longer vertical the argument is no longer valid.

Quote
A small CW tilt along the X axis of the balance arm would explain the apparent drift in the baseline seen in some of the thrust waveforms.   When the cavity has the orientation shown below its CM shifts to the left.  This would reduce the tilt, resulting in an increase in brightness of the reflected light the LDS measures; due to the mirror position being closer to an optimal perpendicular position wrt the light beam.   The increase in brightness corresponds to a decrease in distance; hence the negative slope.   With the device mounted the other way the shift in CM increases the tilt.  This reduces the reflected light and is registered as an increase in distance.   

Is this what you are saying ?


Indeed the X axis is not vertical (it is horizontal, or almost), so the above statement A does apply if we consider rotations around X are not against infinite stiffness. But preliminary rough estimations gave me relative displacements of rest optical length of at least one order of magnitude below signal. Even if not infinitely stiff, the added torsion compliance of faztek beam around X and compliance of tandem flexure bearings around X is not enough. For reasonable thermal CoM's shifts, this is stiff enough , and the optical lever is small enough (optical length d measured at small distance below X) that it would make very little contribution to the signal.

Quote
No actual motion of the beam occurs.  This apparent motion is an optical artifact.   This assumes the Philtec distance sensor is used on the far side.   If it is used on the near side a small CCW tilt along the X axis of the beam would produce the same effect; except requiring much less rotation from the change in CM.

For this twist around X effect, no actual rotation of the beam around Z would occur, but the beam is deformed. I wouldn't qualify that as an "optical artifact". Sorry I'm becoming quite finicky on wordings lately  :)  That would be a real mechanical motion, only not a motion around the "official" Z axis.

We have all reasons to believe the Philtec linear sensor is used in the far range, see attached chart's horizontal units. The initial report (anomalous...) clearly states that it is used around 500m, the vertical readings of the charts are consistent, and Paul March confirms :
...
- That the vertical scale in the charts (indicated in m, 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.
...

Still, there is a factor 10 disparity between the apparent stiffness readings (LDS readings against calibrations pulses alone) and the stiffness needed to explain the 4.5s pseudo-period of oscillations, so this can put a doubt on the readings of vertical scale, a factor 10 here could explain a lot of things.

Regardless of this nagging problem of late, now that we know that Z deviates from strict verticality by a quarter bubble, from statement A above there is now a real possibility that a thermal CoM shift along Y changes angular rest position around the official Z, of relative magnitude compatible with signals, as rotation around Z has a very low stiffness (the restoring torque of flexure bearing around their natural axis of rotation). And such change in angular rest position around Z would record as false "sustained thrusts" in the charts.

Statement B : The validity of real sustained thrust signals now rests on the amount of deviation of Z from vertical, resolution of the contradictions between apparent stiffness around Z, and careful assessment of thermal expansions in vacuum. The sustained duration alone no longer suffice.


Frobnicat:

Your analysis and comments made me go back and look at the current alignment of the Eagleworks torque pendulum and the attached picture indicates that my recollection of the leveling of the bottom beam of the TP being a quarter bubble high at the vacuum chamber door end was a bit exaggerated due to parallax error and a just plain bad memory.  It looks now like less than tenth of bubble low at the door end of the vacuum chamber, but part of that apparent tilt may in reality be due to actual bending of the 1.50 inch square aluminum beam.

Best, Paul M.
Star-Drive

Offline zen-in

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For this twist around X effect, no actual rotation of the beam around Z would occur, but the beam is deformed. I wouldn't qualify that as an "optical artifact". Sorry I'm becoming quite finicky on wordings lately  :)  That would be a real mechanical motion, only not a motion around the "official" Z axis.

We have all reasons to believe the Philtec linear sensor is used in the far range, see attached chart's horizontal units. The initial report (anomalous...) clearly states that it is used around 500m, the vertical readings of the charts are consistent, and Paul March confirms :
...
- That the vertical scale in the charts (indicated in m, 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.
...

Still, there is a factor 10 disparity between the apparent stiffness readings (LDS readings against calibrations pulses alone) and the stiffness needed to explain the 4.5s pseudo-period of oscillations, so this can put a doubt on the readings of vertical scale, a factor 10 here could explain a lot of things.

Regardless of this nagging problem of late, now that we know that Z deviates from strict verticality by a quarter bubble, from statement A above there is now a real possibility that a thermal CoM shift along Y changes angular rest position around the official Z, of relative magnitude compatible with signals, as rotation around Z has a very low stiffness (the restoring torque of flexure bearing around their natural axis of rotation). And such change in angular rest position around Z would record as false "sustained thrusts" in the charts.

Statement B : The validity of real sustained thrust signals now rests on the amount of deviation of Z from vertical, resolution of the contradictions between apparent stiffness around Z, and careful assessment of thermal expansions in vacuum. The sustained duration alone no longer suffice.

I don't think the tilt of the balance beam about the X axis would have to be very much for the resulting change in received light amplitude to register as a shift in position.   The LDS has fractional micron resolution.    Assuming the light pattern from the fiber optic cable has a circular gaussian distribution, for any given distance the maximum light level hitting the detector is when the plane of the mirror is perpendicular to the central axis of the light beam.   Any small deviation ( arc-second) will reduce the light amplitude; which registers as a displacement.     It is impossible to align the LDS perfectly so the angle between the mirror and the light beam is never exactly 90 degrees in X and Y.    The expansion of the cavity due to heating has a very long time constant.   The slow drift in the position between RF pulses looks like a thermal response.
« Last Edit: 03/06/2015 04:24 AM by zen-in »

Offline DIYFAN

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Same here.  The EBay units I've got are #201065780928 and #131442703325 so far in case anyone want to try the same system.

I've decided to try and live up to my screen name and throw my lot in with the replicators.  I have a few questions before I kick off my effort:

1) Why did you decide to go with #201065780928 rather than a frustrum of a cone?  The #201065780928 part looks more like a rectangular slit shape rather than a cone shape.
2) How do you plan on hooking the MA86751B X band oscillator up to the waveguide assembly?
3) It looks like the MA86751B X band oscillator is tunable from 9.9 GHz to 10.6 GHz with power output levels from 10 mW to 100 mW powered by 9-10 Volts DC.  Did you pick this particular oscillator for a reason?
4) Do you expect there to be a resonant frequency within the 9.9 GHz to 10.6 GHz frequency band?
5) Do you plan on putting a dielectric toward one end of the waveguide assembly?
6) With what material do you plan on capping each end of the waveguide assembly?

Although I direct this friendly set of questions to Notsosureofit, Mulletron, and others who are attempting replications, I welcome any forum members to chime in with recommendations or insights.  Can you imagine what would happen if the effect can be shown on such a small scale?  It could cause some ripples and raise a quite a few eyebrows around the world.

Offline zen-in

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Same here.  The EBay units I've got are #201065780928 and #131442703325 so far in case anyone want to try the same system.

I've decided to try and live up to my screen name and throw my lot in with the replicators.  I have a few questions before I kick off my effort:

1) Why did you decide to go with #201065780928 rather than a frustrum of a cone?  The #201065780928 part looks more like a rectangular slit shape rather than a cone shape.
2) How do you plan on hooking the MA86751B X band oscillator up to the waveguide assembly?
3) It looks like the MA86751B X band oscillator is tunable from 9.9 GHz to 10.6 GHz with power output levels from 10 mW to 100 mW powered by 9-10 Volts DC.  Did you pick this particular oscillator for a reason?
4) Do you expect there to be a resonant frequency within the 9.9 GHz to 10.6 GHz frequency band?
5) Do you plan on putting a dielectric toward one end of the waveguide assembly?
6) With what material do you plan on capping each end of the waveguide assembly?

Although I direct this friendly set of questions to Notsosureofit, Mulletron, and others who are attempting replications, I welcome any forum members to chime in with recommendations or insights.  Can you imagine what would happen if the effect can be shown on such a small scale?  It could cause some ripples and raise a quite a few eyebrows around the world.

It doesn't look like that Gunn oscillator (the MA86751B X band oscillator) has a varactor diode.   That would make it difficult to tune.

Offline Notsosureofit

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Same here.  The EBay units I've got are #201065780928 and #131442703325 so far in case anyone want to try the same system.

I've decided to try and live up to my screen name and throw my lot in with the replicators.  I have a few questions before I kick off my effort:

1) Why did you decide to go with #201065780928 rather than a frustrum of a cone?  The #201065780928 part looks more like a rectangular slit shape rather than a cone shape.
2) How do you plan on hooking the MA86751B X band oscillator up to the waveguide assembly?
3) It looks like the MA86751B X band oscillator is tunable from 9.9 GHz to 10.6 GHz with power output levels from 10 mW to 100 mW powered by 9-10 Volts DC.  Did you pick this particular oscillator for a reason?
4) Do you expect there to be a resonant frequency within the 9.9 GHz to 10.6 GHz frequency band?
5) Do you plan on putting a dielectric toward one end of the waveguide assembly?
6) With what material do you plan on capping each end of the waveguide assembly?

Although I direct this friendly set of questions to Notsosureofit, Mulletron, and others who are attempting replications, I welcome any forum members to chime in with recommendations or insights.  Can you imagine what would happen if the effect can be shown on such a small scale?  It could cause some ripples and raise a quite a few eyebrows around the world.

1.  it matches the osc. waveguide and 1st cheap one on EBay.
2.  just bolt them together
3.  I had this one already
4.  probably,  have to calculate when I get the waveguide
5. that's an option
6. TBD  flat pate, detector fitting etc etc

I'll just try a long ( 20 ft ?) pendulum First and see what happens.   Vacuum later.

Online Rodal

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....

I'll just try a long ( 20 ft ?) pendulum First and see what happens.   Vacuum later.
That would also be my first choice: a long pendulum with damping provided by an oil bath. The experiment used by Brito, Marini and Galian (they had battery power, self-contained) to nullify a Mach Lorentz Thruster:
« Last Edit: 03/06/2015 11:43 AM by Rodal »

Offline DIYFAN

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http://www.ebay.com/itm/AERCOM-Microwave-RF-Isolator-Circulator-2-4GHz-20dB-isolation-Low-I-L-TESTED-/281549538390?ssPageName=ADME:L:OU:US:1120
Picked up one of these puppies on Ebay to protect my amp. Another example of broken time reversal symmetry in action.

Got about an oz of very expensive liquid metal from here:
http://www.amazon.com/Gallium-Indium-Eutectic-GaInSn-68-5%25/dp/B00KN92MWW/ref=sr_1_3?ie=UTF8&qid=1425074693&sr=8-3&keywords=galinstan

So back to the copper from way back: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326742#msg1326742
...
Been working with the supplier with a machine shop I posted about way back:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326669#msg1326669
I'm going that route. The quote I got is: price: $120.00 layout + $51.63 for part + freight. So I have to pay the layout, then anyone else who wants one of these:

but built in 16oz copper, with a smooth butt seam inside, and 1/4" flange around edges, can get one for about 50 bucks plus shipping. If all this works out, it'll fulfill my goal of making a replication by DIYers easier. For me, paying the layout plus price about breaks even with buying the sheet myself and fumblefuddeling around trying to solder up a cone at home. So I'm happy. I'll get back with more later, when the items are at home.

Mulletron,

Can you provide me with the contact information (email) of the maker of the custom cone?  What dimensions did you settle on?  I appreciate that you are footing the bill for the layout, thereby lowering the cost for the rest of us.  Kudos to you for that.

Online Rodal

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Same here.  The EBay units I've got are #201065780928 and #131442703325 so far in case anyone want to try the same system.

I've decided to try and live up to my screen name and throw my lot in with the replicators.  I have a few questions before I kick off my effort:

....
3) It looks like the MA86751B X band oscillator is tunable from 9.9 GHz to 10.6 GHz with power output levels from 10 mW to 100 mW powered by 9-10 Volts DC.  Did you pick this particular oscillator for a reason?
4) Do you expect there to be a resonant frequency within the 9.9 GHz to 10.6 GHz frequency band?
.....
Unless your cavity has an unusually small diameter, the problem with 9.9 GHz to 10.6 GHz will be a luxury of resonances rather than a scarcity of natural frequencies:  there may be too many resonant frequencies very close to each other at such a high frequency and therefore difficult to keep the cavity resonating in a pure mode.

No experimenter in the US, UK or China has operated an EM Drive at such a high frequency, and therefore one would be covering new ground.

@Notsosureofit's formula is proportional to the inverse of the frequency to the third power: this would mean (10/2)^3=125 times less thrust.  That's compensated by the square of the Bessel zero function which also appears in the expression, so, depending on the mode shape excited you may end up with higher thrust  (if the excited mode has many wave patterns through the circumference), similar thrust,  or lower thrust (if the excited mode has few wave patterns in the circumferential direction and many wave patterns in the longitudinal direction)  as present experiments...
« Last Edit: 03/06/2015 12:30 PM by Rodal »

Online Mulletron

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http://www.ebay.com/itm/AERCOM-Microwave-RF-Isolator-Circulator-2-4GHz-20dB-isolation-Low-I-L-TESTED-/281549538390?ssPageName=ADME:L:OU:US:1120
Picked up one of these puppies on Ebay to protect my amp. Another example of broken time reversal symmetry in action.

Got about an oz of very expensive liquid metal from here:
http://www.amazon.com/Gallium-Indium-Eutectic-GaInSn-68-5%25/dp/B00KN92MWW/ref=sr_1_3?ie=UTF8&qid=1425074693&sr=8-3&keywords=galinstan

So back to the copper from way back: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326742#msg1326742
...
Been working with the supplier with a machine shop I posted about way back:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326669#msg1326669
I'm going that route. The quote I got is: price: $120.00 layout + $51.63 for part + freight. So I have to pay the layout, then anyone else who wants one of these:

but built in 16oz copper, with a smooth butt seam inside, and 1/4" flange around edges, can get one for about 50 bucks plus shipping. If all this works out, it'll fulfill my goal of making a replication by DIYers easier. For me, paying the layout plus price about breaks even with buying the sheet myself and fumblefuddeling around trying to solder up a cone at home. So I'm happy. I'll get back with more later, when the items are at home.

Mulletron,

Can you provide me with the contact information (email) of the maker of the custom cone?  What dimensions did you settle on?  I appreciate that you are footing the bill for the layout, thereby lowering the cost for the rest of us.  Kudos to you for that.

The cone is the same dims as the DUT at Eagleworks. What was built was based off of this: https://docs.google.com/file/d/0B4PCfHCM1KYoN2VURmltbVlfa3c/edit?pli=1

It is in shipping to me att. I intend to make sure it is good to go, then if no changes are required, the guy who made it will list it on Ebay for around 50 bucks or so. Please give it a few days to arrive. I want to make sure there aren't any problems before it gets put up for sale. That way I accept the risk first. Here's what it looks like.
Challenge your preconceptions, or they will challenge you. - Velik

Online Rodal

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http://www.ebay.com/itm/AERCOM-Microwave-RF-Isolator-Circulator-2-4GHz-20dB-isolation-Low-I-L-TESTED-/281549538390?ssPageName=ADME:L:OU:US:1120
Picked up one of these puppies on Ebay to protect my amp. Another example of broken time reversal symmetry in action.

Got about an oz of very expensive liquid metal from here:
http://www.amazon.com/Gallium-Indium-Eutectic-GaInSn-68-5%25/dp/B00KN92MWW/ref=sr_1_3?ie=UTF8&qid=1425074693&sr=8-3&keywords=galinstan

So back to the copper from way back: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326742#msg1326742
...
Been working with the supplier with a machine shop I posted about way back:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326669#msg1326669
I'm going that route. The quote I got is: price: $120.00 layout + $51.63 for part + freight. So I have to pay the layout, then anyone else who wants one of these:

but built in 16oz copper, with a smooth butt seam inside, and 1/4" flange around edges, can get one for about 50 bucks plus shipping. If all this works out, it'll fulfill my goal of making a replication by DIYers easier. For me, paying the layout plus price about breaks even with buying the sheet myself and fumblefuddeling around trying to solder up a cone at home. So I'm happy. I'll get back with more later, when the items are at home.

Mulletron,

Can you provide me with the contact information (email) of the maker of the custom cone?  What dimensions did you settle on?  I appreciate that you are footing the bill for the layout, thereby lowering the cost for the rest of us.  Kudos to you for that.

The cone is the same dims as the DUT at Eagleworks. What was built was based off of this: https://docs.google.com/file/d/0B4PCfHCM1KYoN2VURmltbVlfa3c/edit?pli=1

It is in shipping to me att. I intend to make sure it is good to go, then if no changes are required, the guy who made it will list it on Ebay for around 50 bucks or so. Please give it a few days to arrive. I want to make sure there aren't any problems before it gets put up for sale. That way I accept the risk first. Here's what it looks like.

If one were to drive the above geometrical dimensions (same dims as the DUT at Eagleworks)



 at the 9.9 GHz to 10.6 GHz previously discussed:

....
3) It looks like the MA86751B X band oscillator is tunable from 9.9 GHz to 10.6 GHz with power output levels from 10 mW to 100 mW powered by 9-10 Volts DC.  Did you pick this particular oscillator for a reason?
4) Do you expect there to be a resonant frequency within the 9.9 GHz to 10.6 GHz frequency band?
.....

instead of the ~1.9 GHz frequency tested at NASA Eagleworks,  one would be exciting very high natural frequencies, with lots of wave-patterns through the circumference and/or through the longitudinal axis: there would be a lot of very different mode shapes bunched up next to each other and it would be extremely difficult to keep it at a pure resonant mode.  A cone with these dimensions would be very difficult to calculate, very difficult to analyze and very difficult to experiment with at 10 GHz. 

Better to excite this cone in the ~2 GHz range.
« Last Edit: 03/06/2015 03:11 PM by Rodal »

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I want to test my own shapes, and cylinders too but I feel it is most important to get to the Eagleworks/Shawyer one first. I want to make it appealing for others to attempt a replication, so I think this is a good way to start.
Challenge your preconceptions, or they will challenge you. - Velik

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