Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1803478 times)

Offline kml

I've been reading up on waveguide math and noticed a very important property of waveguides:

- As you approach cutoff frequency group velocity decreases but guided wavelength increases
- As EM waves enter a dielectric the group velocity decreases but guided wavelength decreases
- Dielectrics also take you further from cutoff frequency, additionally decreasing guided wavelength.

If Shawyer's formula 7 in theorypaper9-4.pdf is correct, this means that in a tapered resonator without dielectric, would accelerate large end forward while a resonator with dielectric at one end would accelerate dielectric end first (regardless of which end has the taper).

Isn't this exactly what happened in the the Eagleworks test where the dielectric disk fell off the small end?

Another consequence of this is that an EmDrive that does not use dielectric could never exceed Q * photon rocket thrust, while an EmDrive with dielectric does not have that limitation.    This is because tapering only reduces momentum transfer at the small end while the large end transfers higher but still less than unguided reflection momentum.   In a resonator with dielectric at one end, the reflections at the dielectric end transfer more momentum than normal (according to Shawyer's guided wavelength theory).

Shawyers formula 7 already incorporates the effect of a dielectric if guided wavelengths are calculated correctly including relative permittivity (which is not hard).  I wonder why he opted to set Er=1 and mur=1 in formula 7 and add in dielectric terms in a very akward and confusing way in later formulas?

Here's a quick spreadsheet I made for rectangular resonators.  It lets you play with different geometry, media, Q, power and frequency.   It calculates guided wavelengths with industry standard formulas.   It calculates thrust using Shawyer's forumula 7 directly adapted for thrust with Q and by not ignoring the media (which then properly affects the guided wavelengths).    You can see how tapered geometry isn't real interesting compared to dielectrics.

http://kl.net/emdrive/kml-emdrive-1.0.xls


It predicts I will get 1.63 milinewtons with my WR-650 waveguide, 3 watts net power, f=1265MHz, Q=5000 and SrTiO3 dielectric.  Scale that up to 30w net and it's 16.2 milinewtons or 1.7 grams of force (!)

Here are the predicted figures with 3w net power, WR-650, f=1265, Q=5000:

HDPE (K=2.25): 72.6 micronewtons
Al2O3 (K=9):  230 micronewtons
SrTiO3 (K=289): 1632 micronewtons

Will I be able to get Q=5000 with those dielectrics?  We'll find out but regardless of Q this will be a good test of the Shawyer Guided Wavelength theory.

Offline SeeShells

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6 inch diameter air bearing. Area of a circle = Pi x diameter 2/4 = 3.142 x 36/4 = 28.28 sq ins
@ 100psi x 28.28 = 2,828 pounds
Support isn't a issue, but design is in making the bottom cavity cupped to keep the top disk in the center and that can be done with air jets in the bottom section and very small .020" groves connecting the jets dispersing the air flow over the bearing and eliminating high pressure areas. 
I could put a small car on this bearing and spin it around without it loosing any centricity of rotation.
What is the minimum speed at which that air bearing (described above) can accurately operate?
Does it require precise manufacturing ?

Or can you give the manufacturer name (or link) to see its design parameters?

Thanks

0 hz static nadda. Yes, it does require good machining but nothing a good lathe can't do. I built one just like this after one of my guys told me it wouldn't work. Don't po the boss ... lmao. (lost the bet and he had to buy the pizza that week) I had an tool room Harrison manual lathe good to +-.00005 ( and had it turned out in about day with all the air channels and air jets machined in with a mill and drill press.

Because of the way the center bearing takes the load it can be sensitive to load and air pressure. It's is like one half of an air bearing spindle thrust bearing but much easier to make. http://www.westwind-airbearings.com/airBearing/documents/AirBearingTechnologybriefv2.pdf

I installed a small stop on the top of the outside bearing. You would put on the load, increase the pressure until the stop engaged and drop the air pressure with your regulator about 10 pounds. You then had all the specs of a thrust bearing without having to have the extreme machining. Cool huh?

Shell

I'll look and see if I still have the drawings and specs but that was 10 years ago and they would be on hard copy.

Offline Rodal

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What is the minimum speed at which that air bearing (described above) can accurately operate?
Does it require precise manufacturing ?

Or can you give the manufacturer name (or link) to see its design parameters?

Thanks

0 hz static nadda. Yes, it does require good machining but nothing a good lathe can't do. I built one just like this after one of my guys told me it wouldn't work. Don't po the boss ... lmao. (lost the bet and he had to buy the pizza that week) I had an tool room Harrison manual lathe good to +-.00005 ( and had it turned out in about day with all the air channels and air jets machined in with a mill and drill press.

Because of the way the center bearing takes the load it can be sensitive to load and air pressure. It's is like one half of an air bearing spindle thrust bearing but much easier to make. http://www.westwind-airbearings.com/airBearing/documents/AirBearingTechnologybriefv2.pdf

I installed a small stop on the top of the outside bearing. You would put on the load, increase the pressure until the stop engaged and drop the air pressure with your regulator about 10 pounds. You then had all the specs of a thrust bearing without having to have the extreme machining. Cool huh?

Shell

I'll look and see if I still have the drawings and specs but that was 10 years ago and they would be on hard copy.

Focusing on Shawyer's EM Drive Demonstrator dynamic test on the air bearing (average speed: one revolution every 6 minutes):

Maximum speed = 2 cm/s  (very slow)  (from Shawyer's data)

Circumferential perimeter rig = (4*28 cm) Pi = 352 cm (using the known EM Drive diameter=28cm as a scale)

Maximum RPM =( (2 cm/s)/( (4*28 cm) Pi) )*(60 s/min) = 0.34 RPM (very slow, about 1 rev every 3 minutes)

Average RPM =(0 + 0.34)/2 RPM= 0.17 RPM (one revolution every 6 minutes) this video shows how slow is the motion of the EM Drive:



See attached the Fig. 7 asynchronous radial runout against shaft speed, on page 8 of the Westwind webpage you noted.  It shows that component of the total error motion (that occurs at noninteger multiples of the rotation frequency, and that is not-periodic, and/or periodic at frequencies that are subharmonics of the rotation frequency)  to increase hyperbolically from 20000 RPM to 2000 RPM (going from right to left on the lower axis).  It shows that component of the radial runout to rise nonlinearly for rotational speeds less than 5000 RPM.  Nothing is shown for less than 2000 RPM, but it is clearly rising.  So the minimum rotational speed shown is ~6000 times greater than Shawyer's maximum RPM (only 0.34 RPM), and more than 10,000 times Shawyer's average RPM.  I also see that Shawyer's moment of inertia and weight distribution seems to be inhomogenous around the perimeter. Admittedly the asynchronous component (the largest peak-to-valley number at each measured angular position) is small at the minimum reported value (2000 RPM) but that RPM (and its associated runout which appears to be rising hyperbolically) is so much larger than Shawyer's maximum 0.34 RPM that I cannot fail to be concerned about the air bearing used by Shawyer to be involved in the strange motion shown in Shawyer's report (the acceleration increasing under decreasing power from an initial acceleration A to a higher acceleration B where B>A, and then with the power off continuing to accelerate, albeit going back to the initial acceleration A (this time under no power).

At average rotational speeds of only 0.17 RPM it looks like the acceleration of the EM Drive would be governed to a significant degree by the peculiarities of the air bearing's air flow hydrodynamics, by the geometrical design (for example flow separation) and by the bearing's machining accuracy.
« Last Edit: 06/09/2015 03:08 PM by Rodal »

Offline Paul Novy

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EMDYIers, seems a lot of the RF injection into the frustum has been monopole antenna (magnatron) or coupling loop (EW). Been trying to think past this...I'll start out with a unity gain 1/2 wave monopole, then the loop, then a colinear array which provides about gain up to about 10dB with series 1/2 wave elements. Since this would exceed a linear dimension in the frustum, was thinking perhaps of a spiral arrangement.

Gain is important in my design, since I'm only planing on about +37dbm to start...FWIW: http://www.nodomainname.co.uk/Omnicolinear/2-4collinear.htm

Oops, forgot the helical pic...


I think that the antena length might have some influence if we consider near field (as an evanescent waves) distribution inside the frustum.

After wikipedia:



http://en.wikipedia.org/wiki/Near_and_far_field

Thanks. Would you recommend 1/2 wavelengths or loops to avoid far-field interactions?

I'm not sure. I have to once again go through all the theory behind this. However, my intuition tells me to try full wavelength antenna and try to somehow fit it inside the frustum (loops, dipole etc.).

I believe that TheTraveller provided better explanation.

Online A_M_Swallow

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{snip}
It is a perplexing problem and obviously not a realistic one, once you consider the power source is external and mass will increase indefinitely.
Todd
Does this amount to with a solar powered EM drive the speed will increase as long as energy is supplied? The energy is stored as mass.
This variable mass
should reduce the acceleration for constant Pin as the velocity increases, giving the device a top speed.
I would draw your attention to my nick  :D
Were this to be true, then this is yet another way to build a perpetual motion machine of the 1st kind, with free energy to spare.  Any system that can vary its mass at will can in principle be engineered into a free energy machine.


You would have to exceed the top speed to extract excess energy. As energy is removed the mass would go down.

You do not actually get to the top speed because that would produce infinite mass and zero acceleration. The system will have rest mass.

Offline rfmwguy

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« Last Edit: 06/09/2015 03:34 PM by rfmwguy »

Offline deltaMass

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{snip}
It is a perplexing problem and obviously not a realistic one, once you consider the power source is external and mass will increase indefinitely.
Todd
Does this amount to with a solar powered EM drive the speed will increase as long as energy is supplied? The energy is stored as mass.
This variable mass
should reduce the acceleration for constant Pin as the velocity increases, giving the device a top speed.
I would draw your attention to my nick  :D
Were this to be true, then this is yet another way to build a perpetual motion machine of the 1st kind, with free energy to spare.  Any system that can vary its mass at will can in principle be engineered into a free energy machine.


You would have to exceed the top speed to extract excess energy. As energy is removed the mass would go down.

You do not actually get to the top speed because that would produce infinite mass and zero acceleration. The system will have rest mass.
I can show you a very simple machine utilising the hypothetical principle of variable mass that readily produces free energy forever. A version can be built for either linear motion in free space or, using a different approach, rotary motion in a gravitational field.

The bottom line is that if you have variable mass then you have perpetual motion and free energy.
« Last Edit: 06/09/2015 04:05 PM by deltaMass »

Offline SeeShells

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What is the minimum speed at which that air bearing (described above) can accurately operate?
Does it require precise manufacturing ?

Or can you give the manufacturer name (or link) to see its design parameters?

Thanks

0 hz static nadda. Yes, it does require good machining but nothing a good lathe can't do. I built one just like this after one of my guys told me it wouldn't work. Don't po the boss ... lmao. (lost the bet and he had to buy the pizza that week) I had an tool room Harrison manual lathe good to +-.00005 ( and had it turned out in about day with all the air channels and air jets machined in with a mill and drill press.

Because of the way the center bearing takes the load it can be sensitive to load and air pressure. It's is like one half of an air bearing spindle thrust bearing but much easier to make. http://www.westwind-airbearings.com/airBearing/documents/AirBearingTechnologybriefv2.pdf

I installed a small stop on the top of the outside bearing. You would put on the load, increase the pressure until the stop engaged and drop the air pressure with your regulator about 10 pounds. You then had all the specs of a thrust bearing without having to have the extreme machining. Cool huh?

Shell

I'll look and see if I still have the drawings and specs but that was 10 years ago and they would be on hard copy.

Focusing on Shawyer's EM Drive Demonstrator dynamic test on the air bearing (average speed: one revolution every 6 minutes):

Maximum speed = 2 cm/s  (very slow)  (from Shawyer's data)

Circumferential perimeter rig = (4*28 cm) Pi = 352 cm (using the known EM Drive diameter=28cm as a scale)

Maximum RPM =( (2 cm/s)/( (4*28 cm) Pi) )*(60 s/min) = 0.34 RPM (very slow, about 1 rev every 3 minutes)

Average RPM =(0 + 0.34)/2 RPM= 0.17 RPM (one revolution every 6 minutes) this video shows how slow is the motion of the EM Drive:



See attached the Fig. 7 asynchronous radial runout against shaft speed, on page 8 of the Westwind webpage you noted.  It shows that component of the total error motion (that occurs at noninteger multiples of the rotation frequency, and that is not-periodic, and/or periodic at frequencies that are subharmonics of the rotation frequency)  to increase hyperbolically from 20000 RPM to 2000 RPM (going from right to left on the lower axis).  It shows that component of the radial runout to rise nonlinearly for rotational speeds less than 5000 RPM.  Nothing is shown for less than 2000 RPM, but it is clearly rising.  So the minimum rotational speed shown is ~6000 times greater than Shawyer's maximum RPM (only 0.34 RPM), and more than 10,000 times Shawyer's average RPM.  I also see that Shawyer's moment of inertia and weight distribution seems to be inhomogenous around the perimeter. Admittedly the asynchronous component (the largest peak-to-valley number at each measured angular position) is small at the minimum reported value (2000 RPM) but that RPM (and its associated runout which appears to be rising hyperbolically) is so much larger than Shawyer's maximum 0.34 RPM that I cannot fail to be concerned about the air bearing used by Shawyer to be involved in the strange motion shown in Shawyer's report (the acceleration increasing under decreasing power from an initial acceleration A to a higher acceleration B where B>A, and then with the power off continuing to accelerate, albeit going back to the initial acceleration A (this time under no power).

At average rotational speeds of only 0.17 RPM it looks like the acceleration of the EM Drive would be governed to a significant degree by the peculiarities of the air bearing's air flow hydrodynamics, by the geometrical design (for example flow separation) and by the bearing's machining accuracy.
It could very well be governed some by the air bearing, but we also see the same effects of thrust after power shut off in other tests without an air bearing. I can't correlate the two observed actions and say it was a air bearing abnormality when the other tests had no air bearing.

If you remember I said when we first did a air bearing like this where my tech said I feel the air flows coming out of the bearing? He was right and after some thought we figured out that the air pressures between the plates were nonuniform with high pressure gradients radiating out from the air jets down to low pressures where where were no jets. This nonuniformity in pressures would lead to the air swirling in vortexes (just like a tornado), these vortexes would impart momentum to the top plate causing it to rotate.

This is one reason why I put air guides (channels) between the air jets in a crisscross pattern to distribute the air pressure more uniformly and dampen any rotational actions involving air flow subharmonics that could impart movement to the top plate at 0 RPM.

By putting a high frequency microphone onto the metal casing we could see on a scope and coupled with a spectrum analyzer the acoustics of the air bearing and  the harmonic frequencies of the air flows. It became a good tool for fine tuning a air bearing.

Shell

Offline deltaMass

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In an attempt to be as pragmatic as possible, I'd say that Shawyer's results on that air bearing are highly questionable and that the experiment should be repeated with something more robust.  The fact that rotating gizmos are present on that platform just adds to the farce of it.

Offline Rodal

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It could very well be governed some by the air bearing, but we also see the same effects of thrust after power shut off in other tests without an air bearing. I can't correlate the two observed actions and say it was a air bearing abnormality when the other tests had no air bearing.
...
I'm sorry I don't understand in which other tests, in which 

Quote from: SeeShells
we also see the same effects of thrust after power shut off in other tests without an air bearing 

are you referring to other EM Drive tests (other than the Shawyer Demonstrator dynamic test we were discussing) ?   
« Last Edit: 06/09/2015 04:15 PM by Rodal »

Offline hhexo

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The kind of distortion you would need for something like your_c_in_my_frame = 1m/s boggles the mind.
[Edit] ...or maybe not! http://www.nature.com/nature/journal/v397/n6720/abs/397594a0.html
... wow. I think that's a bit too much to digest at 1am here. :) I'll go back to trying to make sense of this tomorrow.

I'm doing my best to grapple with this thing. I think I am bridging to new understanding, right or wrong has yet to be determined. Please bare with me and thank you for your comments.

Just FYI: In GR, the coordinate speed of light is a variable;

ds2 = -g00c2dt2+g11dx2...

For light, ds = 0

So we get,

(dx/dt)2 = c2g00/g11

or simply, dx/dt = c/K

where K is the refractive index of the vacuum, i.e., the gravitational field. It amounts to the difference between how much space-time has been altered from what we define as |guv|=1, where c = 1, not 1/K.

Ok... so, if I understand correctly...
In my "vacuum" reference frame I see the speed of light as c.
The radiation going through a material or waveguide or gravity field with refractive index K is moving, in my "vacuum" reference frame, at c/K. No question there.

If I were riding on one of the photons in the accelerated frame, or if I were living in the accelerated frame, would I still measure the speed of light as if it were c, or as c/K, with respect to the coordinates in the accelerated frame?

In the former case, the 1/K factor is simply the coordinate transformation for the value of the speed of light from measurements in the accelerated reference frame to measurements in the "vacuum" reference frame (or a frame with acceleration/gravity close to zero), right?
But then a consequence is that my measurement of the inertia of the "thing" in the accelerated reference frame and its measurement of its inertia disagree.

Suppose I have a box containing an accelerated reference frame, like you're supposing the EmDrive is. Suppose the EmDrive is running and it has achieved half its limit velocity in my frame of reference, let's say that is 0.5m/s.
Now, if try to accelerate the EmDrive with some effect within the EmDrive itself, I encounter an inertia as measured in the EmDrive's system, where it's believing that it's running at half c, so the gamma is significant.
If I instead accelerate it by picking it up and throwing it in my reference system, what happens?
Can I just push it past its limit velocity? (what happens to its insides?!)
Or is my acceleration then transformed in its system, and therefore does it resist being pushed exactly as if it had a significant gamma in my system? This doesn't seem to make sense, because with an arbitrarily powerful EmDrive I could create an almost "immovable object" in my reference frame. I'm confused. Not even black holes are immovable.

So it must be that entities in the accelerated reference frame do measure the speed of light as c/K within their coordinate system. Right?
I'm not sure what the consequence of that is... Basically, if I then accelerate a running EmDrive conventionally past c/K using stuff in my "vacuum" reference frame, do I create an event horizon within the EmDrive, and do I prevent anything from ever happening in there? Do I effectively stop light?

Another example question: if I take a chunk of material with a refractive index such that the speed of light is just 17m/s (like the ultracool gas of sodium atoms in the paper I referenced), can I pick it up and move it at 20m/s? If yes, do I create a black hole in the chunk of material?

Offline SeeShells

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It could very well be governed some by the air bearing, but we also see the same effects of thrust after power shut off in other tests without an air bearing. I can't correlate the two observed actions and say it was a air bearing abnormality when the other tests had no air bearing.
...
I'm sorry I don't understand in which other tests, in which 

Quote from: SeeShells
we also see the same effects of thrust after power shut off in other tests without an air bearing 

are you referring to other EM Drive tests (other than the Shawyer Demonstrator dynamic test we were discussing) ?
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1386529#msg1386529

Offline Rodal

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I added a lot of information and references on the EM Drive Wiki for Experimental Results: http://emdrive.wiki/Experimental_Results

Please notice:

1) We still have some way to go to model the vacuum of LEO (low Earth orbit) in these EM Drive experiments.  The only EM Drive experiments reported in a partial vacuum are the NASA experiments conducted since the end of December 2014.  (R. Shawyer, Prof. Yang have not reported, to my knowledge, tests in partial vacuum).  However, these NASA vacuum tests were conducted at an ambient pressure:

1.52*10^8 lower pressure than ambient pressure

100 to 50,000 times greater pressure than what is reported for LEO (low Earth orbit)

5*10^11 times greater than what is reported for outer space

2) We still have to include the data for the NASA test done in vacuum with the EM Drive rotated 180 degrees (which gave significantly lower reported thrust measurements).
« Last Edit: 06/09/2015 04:50 PM by Rodal »

Offline Rodal

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It could very well be governed some by the air bearing, but we also see the same effects of thrust after power shut off in other tests without an air bearing. I can't correlate the two observed actions and say it was a air bearing abnormality when the other tests had no air bearing.
...
I'm sorry I don't understand in which other tests, in which 

Quote from: SeeShells
we also see the same effects of thrust after power shut off in other tests without an air bearing 

are you referring to other EM Drive tests (other than the Shawyer Demonstrator dynamic test we were discussing) ?
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1386529#msg1386529

I see a huge difference between the continuing acceleration (speed increasing after power off) in the dynamic test for ~55 seconds after power off,

with the static test showing a continuing force for a few seconds after power off and then a big fall of the force (I did take into account that the dynamic test shows 200 second total time span while the static test shows 100 seconds total time span).

Same EM Drive (Demonstrator) tested under two different set-ups, here one on top of each other for comparison :

air bearing  (upper figure, horizontal scale span=  200 seconds)
vs
balance  (lower figure, horizontal scale span=100 seconds)
« Last Edit: 06/09/2015 05:20 PM by Rodal »

Offline SeeShells

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In an attempt to be as pragmatic as possible, I'd say that Shawyer's results on that air bearing are highly questionable and that the experiment should be repeated with something more robust.  The fact that rotating gizmos are present on that platform just adds to the farce of it.
I'm not standing up for him but I am trying to be highly objective. To understand what we are seeing in some of these abnormalities in the tests he was running is my goal. If they are artifacts of the air bearing we need to try and understand that they truly are from the bering and hopefully not repeat the same error producing component in another test.
Honestly you would be better off just hanging the device(s) from the ceiling with a thin cable that the characteristics are well known to input the variables into the final thrust values. A air bearing while offering good advantages in an almost frictionless surface it also can introduce variables that are almost impossible to know. This is why I asked did they build it or did they use a OEM's design and so far we don't know which it was so it's a total unknown variable and everything is up in the air.

Offline SeeShells

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It could very well be governed some by the air bearing, but we also see the same effects of thrust after power shut off in other tests without an air bearing. I can't correlate the two observed actions and say it was a air bearing abnormality when the other tests had no air bearing.
...
I'm sorry I don't understand in which other tests, in which 

Quote from: SeeShells
we also see the same effects of thrust after power shut off in other tests without an air bearing 

are you referring to other EM Drive tests (other than the Shawyer Demonstrator dynamic test we were discussing) ?
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1386529#msg1386529

I see a huge difference between the continuing to acceleration (speed increasing after power off) in the dynamic test for ~55 seconds after power off,

with the static test showing a continuing force for a few seconds after power off and then a big fall of the force (I did take into account that the dynamic test shows 200 second total time span while the static test shows 100 seconds total time span).

Same EM Drive (Demonstrator) tested under two different set-ups, here one on top of each other for comparison :

air bearing  (upper figure, horizontal scale span=  200 seconds)
vs
balance  (lower figure, horizontal scale span=100 seconds)

The other thing we need to look at because of the commonality of thrust after power is turned off. It is there and even though they are different in some amount of time. Looking at everything I have to ask, even though it may be far fetched. (HA! here we are talking about a reactionless drive and i say far fetched). Are we seeing an artifact from the EMdrive itself? Are we somehow seeing the drive re-establish its frame reference to the outside world after thrust?  I need to mull this one over for a bit as it going to require more than just figuring out the abnormalities of an air bearing.

Offline deltaMass

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Once again, I must mention that there are spinning fans on the test rig. A HD drive also.

Online WarpTech

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You would have to exceed the top speed to extract excess energy. As energy is removed the mass would go down.

You do not actually get to the top speed because that would produce infinite mass and zero acceleration. The system will have rest mass.
I can show you a very simple machine utilising the hypothetical principle of variable mass that readily produces free energy forever. A version can be built for either linear motion in free space or, using a different approach, rotary motion in a gravitational field.

The bottom line is that if you have variable mass then you have perpetual motion and free energy.

Really? How? Where does the extra free energy come from?


Offline rfmwguy

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Once again, I must mention that there are spinning fans on the test rig. A HD drive also.

Yep, good reason to make the DUT as low of a mass as possible...the less variables the better. KISS and lightweight. If the emdrive is scalable in power, we should be able to see results a few dozen dbm below Shawyers high power tests.

Helpful watts to dbm converter: http://www.everythingrf.com/rf-calculators/watt-to-dbm

Offline deltaMass

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You would have to exceed the top speed to extract excess energy. As energy is removed the mass would go down.

You do not actually get to the top speed because that would produce infinite mass and zero acceleration. The system will have rest mass.
I can show you a very simple machine utilising the hypothetical principle of variable mass that readily produces free energy forever. A version can be built for either linear motion in free space or, using a different approach, rotary motion in a gravitational field.

The bottom line is that if you have variable mass then you have perpetual motion and free energy.

Really? How? Where does the extra free energy come from?
The rotary device is the simplest. A balanced wheel with two equal masses A,B diametrically placed, one of which (A) is alterable by means unspecified. When A is descending it is made heavier. Thus each half cycle the wheel undergoes acceleration.
The linear version requires no gravity and can operate in free space. It consists of a variable mass "puck" losslesssly bouncing between two walls of a container. When it strikes the "front" wall it is made heavier. The container experiences a steady acceleration in the forward direction.
The full descriptions are attached

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