#### aero

• Senior Member
• Posts: 2743
• 92129
• Liked: 704
• Likes Given: 237
##### Re: EM Drive Developments
« Reply #2220 on: 10/18/2014 02:28 AM »
Using the photo of Shawyer's Experimental thruster from the PDF document with screen zoom to fit, and using a pixel measurement tool, I measured the big diameter = 759 pixels, small diameter = 496 pixels, and length = 725 pixels. From the PDF document the cavity diameter is given as 160 cm. Using this, I converted to meters as follows:
w_big = 759 pixels = 0.160 meters
w_small= 496 pixels = 0.105 meters
length = 725 pixels = 0.153 meters

I very deliberately chose my corner points where I thought they were. Others will very deliberately choose corner points where they think they are. Our measurements will differ because our corner points will differ. That is OK because we are trying to reach a consensus.

There is of course the question of just what Shawyer referred to in his paper when he wrote that the diameter was 160 mm. Which diameter, inside, outside, outside the supporting ring?

Oh well, the best we can do is the best we can do, and it will be good enough. (We all hope)
« Last Edit: 10/18/2014 02:33 AM by aero »
Retired, working interesting problems

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2221 on: 10/18/2014 02:43 AM »
FWIW:

I converted the JPEG to a 8 bit gray TIF; imported into AutoCAD R14; scaled it so the big end was 28 cm.  To an arbitrary level of accuracy, since these are old eyeballs.:

1st Flange to 2nd flange:  3.0214284 cm
2nd flange to Cylinder 16.59242861 cm
Cylinder: 13.5771431 cm

Diameter of big end: 28 cm
Diameter of cylinder: 17.2052288 cm

Nuts to you all.

Thanks kernosabe.  You raised this to a new level with AutoCAD.

Great job.

Now, can you do the same for the small Shawyer drive (    http://forum.nasaspaceflight.com/index.php?topic=29276.msg1272736#msg1272736   )?

Only read this if you feel like double checking...what is the meaning of big end

Is big end the biggest possible end or you make a difference between big end and biggest end ?

not clear as to whether big end for you is the biggest end or just the big end short of the biggest one

not clear on whether you count first flange from the right or from the left

not clear as to whether you call big end the one at the 4th flange or the one at the 3rd flange starting from the left

me think you did it right, but just in case...

« Last Edit: 10/18/2014 03:17 AM by Rodal »

#### aero

• Senior Member
• Posts: 2743
• 92129
• Liked: 704
• Likes Given: 237
##### Re: EM Drive Developments
« Reply #2222 on: 10/18/2014 03:12 AM »
why don't you just draw a picture of it and put dimension on it
Retired, working interesting problems

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2223 on: 10/18/2014 03:29 AM »
Yes, it would help if you can attach a file that people without AutoCad can open.  I tried to open your dxf file with Mathematica and this is what I got:
« Last Edit: 10/18/2014 03:31 AM by Rodal »

#### aero

• Senior Member
• Posts: 2743
• 92129
• Liked: 704
• Likes Given: 237
##### Re: EM Drive Developments
« Reply #2224 on: 10/18/2014 06:02 AM »
@Rodel

Slope and taper are not the same. Slope = taper/2 . Both are related to the half angle of the cone by the inverse sine function. For me, it is much easier and more accurate to measure the taper of the cone from the photograph.

Select 2 axially separated points on the cone, measure the diameter at those two points and the axial distance between them. The taper is the positive difference of the two diameters divided by the axial distance between them. The diameter at any axial distance x from the larger diameter (d-large) in the direction of the smaller diameter is then
dia. = d-large - x * taper, or if you measure x from the small diameter (d-small) in the direction of the larger diameter,
dia. = d-small + x * taper

So taper is the rate of change of diameter with distance.

Or it could be a long, skinny candle!

I hope we're done with this now.
« Last Edit: 10/18/2014 06:19 AM by aero »
Retired, working interesting problems

#### Mulletron

• Full Member
• Posts: 1111
• Liked: 775
• Likes Given: 1012
##### Re: EM Drive Developments
« Reply #2225 on: 10/18/2014 09:07 AM »

"Still struggling to see how the momentum conservation would propagate to rest of cosmos in some "photon Unruh" generated perturbation, like pushing on the walls of its own universe or pushing on one's own acceleration. Surely this costs some energy, how can this energy be less than   c*acquired_momentum   or else borrowed from some potential, that is, communicated to the outside ?"

Yes, I agree. As I have said, a HUGE "I Believe Button" was pressed on this assumption. I provided data to show how how conservation of momentum inside the unit doesn't amount to a conservation outside.

The unit still must experience a force from outside in order to move.

http://gr.physics.ncsu.edu/files/babson_ajp_77_826_09.pdf page 2
http://arxiv.org/ftp/arxiv/papers/1012/1012.5264.pdf  page 2

It isn't enough to just say that momentum was conserved and therefore it just moves, because it just does. That ignores hundreds of years of established science.
Challenge your preconceptions, or they will challenge you. - Velik

#### IslandPlaya

• Full Member
• Posts: 582
• Outer Hebrides
• Liked: 163
• Likes Given: 166
##### Re: EM Drive Developments
« Reply #2226 on: 10/18/2014 09:10 AM »

"Still struggling to see how the momentum conservation would propagate to rest of cosmos in some "photon Unruh" generated perturbation, like pushing on the walls of its own universe or pushing on one's own acceleration. Surely this costs some energy, how can this energy be less than   c*acquired_momentum   or else borrowed from some potential, that is, communicated to the outside ?"

Yes, I agree. As I have said, a HUGE "I Believe Button" was pressed on this assumption. I provided data to show how how conservation of momentum inside the unit doesn't amount to a conservation outside.

The unit still must experience a force from outside in order to move.

http://gr.physics.ncsu.edu/files/babson_ajp_77_826_09.pdf page 2
http://arxiv.org/ftp/arxiv/papers/1012/1012.5264.pdf  page 2

It isn't enough to just say that momentum was conserved and therefore it just moves, because it just does. That ignores hundreds of years of established science.
Mach's principle?

#### Mulletron

• Full Member
• Posts: 1111
• Liked: 775
• Likes Given: 1012
##### Re: EM Drive Developments
« Reply #2227 on: 10/18/2014 10:31 AM »
Well I've been busy as heck over the last few days getting ready for a board. Some observations I have are:

The "statistical outlier," (circled in green) given the small sample size, I don't think we can do a statistical analysis on this, but the data is very telling nonetheless....

Given the shape of a TM211 cell within a conical cavity, one can easily see where resonant operation of the cavity is very dependent on a very small frequency bandwidth. A small change in frequency changes the mode shape, thus changing the RF field's interaction with the dielectric. Apart from my drawing ability, the attachment is intended to give you a rough idea how frequency changes the mode cells in TM211. I don't have access to COMSOL to actually see exactly what the difference is.

It is clear that thrust is not solely a function of scaling with Q. The mode shape is more important than Q.
I'm not alone here:
http://nextbigfuture.com/2014/08/full-nasa-cannae-drive-and-emdrive-test.html

http://forum.nasaspaceflight.com/index.php?topic=29276.msg1268788#msg1268788

I really need more data. The conclusion of the NASA paper (http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf) mentions future use of higher k dielectric materials, vice PE/PTFE. Page 21 "This resonator material has a relative permittivity that is an order of magnitude higher than our current tapered cavity test article resonator material." I'd love to know what this material is. Even my idea of using PVDF (rp between 8-12) is not an order of magnitude higher than the 2.1-2.25 rp of PE/PTFE.
« Last Edit: 10/18/2014 01:20 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

#### Mulletron

• Full Member
• Posts: 1111
• Liked: 775
• Likes Given: 1012
##### Re: EM Drive Developments
« Reply #2228 on: 10/18/2014 11:39 AM »
http://vixra.org/pdf/1410.0067v1.pdf

Another theory of how EMdrive works.

This paper is neat and all (this guy melted my brain at the bottom of page 2, see gravity), but it once again ignores the experimental finding that:

Nasa report page 18:
"There appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber."

Interesting reading nonetheless. He put some pretty big wings on dem pigs.

I'm a firm believer that we don't need to rewrite physics in order to find an explanation for EMdrive, even if you happen to slap some polish on GR (MiHsC) along the way.

There isn't much modification to inertia that can be done here on good ol planet Earth.

What's left are experimental artifacts (heat, EM leakage, etc) and the cause for anomalous thrust. NASA seems to think that anomalous thrust is inextricably linked to the dielectric.
« Last Edit: 10/18/2014 12:12 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2229 on: 10/18/2014 12:50 PM »

Another way to get at the length of the cavity is to look at the half wavelength multiples for resonance. But the wavelength is so short that it is not very helpful. Knowing the length and the wall taper (=.53) will give the small end diameter. I assume that the cone extends inside the cylinder some unknown distance.

lamda   n   2d=n*Lamda    d, m
0.12236   1   0.122364269    0.0612
0.12236   2   0.244728537    0.1224
0.12236   3   0.367092806    0.1835
0.12236   4   0.489457074    0.2447
0.12236   5   0.611821343    0.3059
0.12236   6   0.734185611    0.3671
0.12236   7   0.85654988    0.4283

I think we've had guesses for all of those values of n, except perhaps n=4. But maybe n = 3, as it does for Brady's device.

wavelength = c / frequency

For both the experimental and demonstrator drives of Shawyer

frequency = 2.45 GHz

therefore the microwave wavelength for both the experimental and the demonstrator Shawyer drives is:

wavelength = 299792458 (m/s) / 2.45*10^9 (1/s)
= 0.12236 m

The dimensions of Shawyer's demonstrator drive (from http://forum.nasaspaceflight.com/index.php?topic=29276.msg1272692#msg1272692 ) are:

Large Base Diameter = 0.28 m
Small Base Diameter = 0.1679 m
LengthOfCone = 0.2089 m
LengthOfCylinder=0.13577 m

2*Large Base Diameter / wavelength =  4.58
2*Small Base Diameter / wavelength =  2.74
2*LengthOfCone / wavelength =  3.42
2*(LengthOfCone+LengthOfCylinder) / wavelength =  5.64
2*(LengthOfCone+(1/2)*(LengthOfCylinder)) / wavelength = 4.52

Force =(   PowerInput*Q / (c/wavelength)  )*(1/SmallDiameter-1/LargeDiameter)

experimental and demonstrator frequency = 2.45 GHz

c / 2*LengthOfCone  = 0.718 GHz
c / 2*(LengthOfCone+LengthOfCylinder)= 0.435 GHz
c /2* (LengthOfCone+(1/2)*(LengthOfCylinder))= 0.542 GHz
c / 2*(2*0.12236 m)= 0.613 GHz

==> For Shawyer's Demonstrator drive the "frequency" in McCulloch's calculation should be c / 2*(2*0.12236 m)= 0.613 GHz instead of 2.45 GHz, therefore the predicted force value should be 2.45/0.613 = 4 times greater based on the actual wavelength.  Based on the cavity length, the predicted force should be ~ 2.45/1.083 = 4.52 times greater

EDIT: Thanks to aero for catching an error I made missing the factor of 2
« Last Edit: 10/18/2014 06:45 PM by Rodal »

#### JohnFornaro

• Not an expert
• Senior Member
• Posts: 9162
• Delta-t is the salient metric.
• Planet Eaarth
• Liked: 610
• Likes Given: 314
##### Re: EM Drive Developments
« Reply #2230 on: 10/18/2014 12:56 PM »
Well I've been busy as heck over the last few days getting ready for a board.

2x4?  2x6?  2x8?

C'mon man.  Without numbers, this is just gibberish.
Sometimes I just flat out don't get it.

#### Mulletron

• Full Member
• Posts: 1111
• Liked: 775
• Likes Given: 1012
##### Re: EM Drive Developments
« Reply #2231 on: 10/18/2014 01:17 PM »
Well I've been busy as heck over the last few days getting ready for a board.

2x4?  2x6?  2x8?

C'mon man.  Without numbers, this is just gibberish.

8, 12, 16.
Yeah I know, but there isn't enough data to crunch numbers. The only numbers I really have are wavelengths. We can make some up? In any event, you gotta be able to visualize the mode shapes.

Just a rough back of the envelope figure I get is length of cone is ~.15 meters ~6.1 inches, rounded. That is based off TM211 and the frequency. That .15 meters is a perfect wavelength. The cavity can be operated above or below that so that doesn't inform me of cavity size. But if the test chamber is 30 inches wide, it doesn't jive. Looking at the pics.

I need to be able to do what this guy: http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html is doing. Because I don't have the COMSOL software.

And see if the dielectric is in or out of the field more or less, when conditions are like page 18.

A hard look at figure 18, looks like the small end is about 6 inches wide to me, and the other end 12 inches. I see 2 magnetic modes in width (blue) and the the gray circle appears to be about the width of the PE discs. I can't say for sure because there is no depth...

When I get home to Autocad, I can do a raster image import and draw some construction lines, and hopefully get some dims from the bottom pic.
« Last Edit: 10/18/2014 02:18 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

#### JohnFornaro

• Not an expert
• Senior Member
• Posts: 9162
• Delta-t is the salient metric.
• Planet Eaarth
• Liked: 610
• Likes Given: 314
##### Re: EM Drive Developments
« Reply #2232 on: 10/18/2014 01:42 PM »
Yes, it would help if you can attach a file that people without AutoCad can open.  I tried to open your dxf file with Mathematica and this is what I got:

You want some cheese with your whine?
Sometimes I just flat out don't get it.

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2233 on: 10/18/2014 02:03 PM »

...the wavelength is so short ...

As you stated, McCulloch's formula

Force =(   PowerInput*Q / (frequency)  )*(1/SmallDiameter-1/LargeDiameter)

needs to be modified to something like this, to be consistent with his theory

Force =(   PowerInput*Q / (c/wavelength) )*(1/SmallDiameter-1/LargeDiameter)

Question is, what is the wavelength to use in the above formula. In McCulloch's theory this wavelength is defined as the peak wavelength of the Unruh energy spectrum, the wavelength that corresponds to the maximum energy in the Unruh spectrum  (see page 6 of http://arxiv.org/pdf/astro-ph/0612599v1.pdf  )

CHOICE 1:  Using the total cavity length (where totalCavityLength=LengthOfCylinder+LengthOfCone)

Force =(   PowerInput*Q / fL)*(1/SmallDiameter-1/LargeDiameter)

where fL = c/(2*totalCavityLength)

essentially assuming that the wavelength that corresponds to the maximum energy in the Unruh spectrum has 2 times the same length as the Total Cavity Length

CHOICE 2:  Using the multiple of the microwave wavelength that fits inside the total cavity length

Force =(   PowerInput*Q / fIP)*(1/SmallDiameter-1/LargeDiameter)

where fIP=microwaveFrequency/IntegerPart[2*totalCavityLength / (c/microwaveFrequency)]

where IntegerPart is the function that takes only the integer part of a number.  For example, IntegerPart[2.834]=2

essentially assuming that the wavelength that corresponds to the maximum energy in the Unruh spectrum has the same length as the largest multiple of the microwave wavelength that fits inside the Total Cavity Length

These two choices are identical only when

2*totalCavityLength / (c/microwaveFrequency)=IntegerPart[2*totalCavityLength / (c/microwaveFrequency)]

Otherwise these two choices differ only by the fractional part of the ratio 2*totalCavityLength / (c/microwaveFrequency)

EDIT: Thanks to aero for catching an error I made missing the factor of 2
« Last Edit: 10/18/2014 06:44 PM by Rodal »

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2234 on: 10/18/2014 02:16 PM »
Yes, it would help if you can attach a file that people without AutoCad can open.  I tried to open your dxf file with Mathematica and this is what I got:

You want some cheese with your whine?

Hey hey kernosabe.

Nicely done!

OK now one can see why numbers are slightly different:  parallax.
« Last Edit: 10/18/2014 04:23 PM by Rodal »

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2235 on: 10/18/2014 03:21 PM »
I still see writing wanting to add the need of extraneous "external forces" to conservation of momentum and conservation of energy and variational principles.  Those principles already contain the concept of force in them, so it doesn't need to be added. It is well known that Newton's law follows from the Lagrangian. The Lagrangian is more general.  Newton was clear as to the fact that he could not explain the force of gravity, which he just postulated.  In General Relativity, the force of gravity is not explained as a force either,  gravity results from the geodesic motion in 4 dimensional spacetime.  No graviton particles have ever been found yet we calculate the effects of the force of gravity ever since Newton, and with Einstein more accurately.
Physical problems are solved with conservation principles like conservation of momentum, conservation of energy, and variational principles.  There is no "force principle". In Weight = m g, the force of gravity is never explained, it is postulated.  F = ma applies to rigid bodies, to solve actual problems in continuum mechanics one has to use the concept of stress tensor and solve the equations based on conservation principles and variational principles.  To obtain forces one has to integrate the equations over given surface areas.
F=ma is a simple form of the equations of motion that follow from the Lagrangian.  F=ma is taught in elementary Physics courses, at the level of rigid bodies and lumped masses, and non-canonical equations.  The Lagrangian and variational principles is taught in more advanced courses.  In Mechanics this is known from the time of Euler and ultimately Cauchy, who precisely defined the concept of stress tensor.  The concept of force in mechanics has always remained an intuitive postulate.  It is a postulate (see Truesdell books on Rational Mechanics).  The equilibrium equations (such as Newton's law) for complicated systems follow from the Lagrangian and the Hamiltonian.

The Lagrangian is equivalent to Newton's laws of motion, but it has the advantage that it takes the same form in any system of generalized coordinates, and it is better suited to generalizations.

For this case, where we have an inverted pendulum with nonlinear coupled modes, for example, it can be solved readily with the Lagrangian (and Newton's equlibrium equations in canonical form follow automatically from it, which would have been extremely difficult to obtain in canonical form otherwise).

If McCulloch's inertial modification theory applies to the microwave EM drives (a big if that is some distance from being shown) the motion and the force follow from conservation of momentum under inertial modification due to Unruh radiation.  The McCulloch force can be computed and he shows a formula for that force.  As to what is the physical mechanism behind the motion and the force, the physical mechanism is the Unruh radiation, this is clearly pointed out in McCulloch's papers.  Now, one may question (with good justification) that inertial modification even if it applies to other particles it may not apply to "massless" particles like photons, or even if it ever applies to photons, one may pose that it may apply to photons under extreme black-hole gravitational attraction but not to photons in a microwave drive, but the discussion about lack of "external forces" is a distraction.  The same argument could be used to argue that a mass cannot be accelerated by gravity because the gravity "force" has never been explained as a force arising from a particle (we have never found gravitons).

Also the effort to try to explain everything in terms of analogies to the forces that humans are familiar with in their everyday life, although natural for all human beings, it is ultimately misguided when applied to photons.  Feynman taught that in analyzing photons one should completely dispense with any analogies to forces that humans are familiar with. Photons are both a particle and a wave.  They are not a particle. They are not a wave.  They behave in counter-intuitive ways (i.e. 2 slit experiment). General physics principles like conservation of momentum, conservation of energy and variational principles should be used instead of appealing to the intuitive concept of forces on rigid bodies. Newton's law follows from the Lagrangian.
« Last Edit: 10/18/2014 04:39 PM by Rodal »

#### JohnFornaro

• Not an expert
• Senior Member
• Posts: 9162
• Delta-t is the salient metric.
• Planet Eaarth
• Liked: 610
• Likes Given: 314
##### Re: EM Drive Developments
« Reply #2236 on: 10/18/2014 04:21 PM »
Nicely done!

Tanks.

Sometimes Mohammed cain't git to da mountain, an he cai'nt git da mountain to come to him, so he must draw and eyeball the dimensions of the mountain.

As you can see, the placement of the guidelines is a complete and total judgement call, and we don't know if there's a squeeze factor in the original JPEG. Were I trying to keep something secret while pretending to reveal all, that's what I would do, when 'publishing' my work.

That, and silence on important details.  What the heck izzat geared gizmo, fo' zample? and how many ounces of CHBW are there in the copper can?

moving right along, howsomeever.  you got some frequencies.  You got some dimensions.  Izzit possible to run one of Frobnicat's programs where he plays multiple frequencies around multiple copper can dimensions, within some kinda statistical limits?  And see if anything rings a bell, so to speak?

You da immam.
« Last Edit: 10/18/2014 04:22 PM by JohnFornaro »
Sometimes I just flat out don't get it.

#### Mulletron

• Full Member
• Posts: 1111
• Liked: 775
• Likes Given: 1012
##### Re: EM Drive Developments
« Reply #2237 on: 10/18/2014 04:36 PM »

It is moot whether or not gravity has been explained as a graviton, entropic, geometric, or whatever. It is a force. Objects in a gravitational field experience that force.

Objects such as copper cans must experience a force in order to experience a change in their acceleration.

Any notion that momentum can be gained from photons inside a cavity is just false. It has no bearing on wave/particle duality. A massless particle in motion has momentum. Unfortunately you can't use that momentum to gain linear momentum from within a closed system. The sum of all forces inside cancel out.

For macro objects, like copper cans, it is a simple as F=MA. No giant paragraph needed.

This one simple concept seems to get lots of people.
Challenge your preconceptions, or they will challenge you. - Velik

#### Mulletron

• Full Member
• Posts: 1111
• Liked: 775
• Likes Given: 1012
##### Re: EM Drive Developments
« Reply #2238 on: 10/18/2014 04:40 PM »
Nicely done!

"That, and silence on important details.  What the heck izzat geared gizmo, fo' zample? and how many ounces of CHBW are there in the copper can?"

Those gears are Shawyer's answer to compensating for doppler shift by lengthening and shortening the cavity accordingly.

There's 2 ways to bring a cavity into resonance. 1: change the size of the cavity to match your frequency 2: change your frequency to match the cavity.

Smaller cavity=higher frequency.

My sources are http://www.emdrive.com/IAC13paper17254.v2.pdf and his latest patent someone recently posted.
« Last Edit: 10/18/2014 04:51 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

#### Rodal

• Senior Member
• Posts: 5838
• USA
• Liked: 5919
• Likes Given: 5259
##### Re: EM Drive Developments
« Reply #2239 on: 10/18/2014 04:48 PM »
On one hand "gravitational attraction" is a force (never mind explaining why it is a force) and reaction from jet exhaust is also a force (using circular arguments based on action and reaction).

The concept of force intuitive remains and since it was explained in elementary physics it is comforting, but Unruh radiation cannot lead to a force, well just because Unruh radiation is not familiar, unlike the already assimilated concepts of gravitational attraction (which drops apples on people's heads to wake them up) or a jet exhaust (which ejects water on people's faces from a water hose).

Every unexplained force that drops things on people's faces to wake them up and were discussed in elementary physics qualify as a force.

Forces that do not drop things on people faces and were not learnt in elementary physics must not be forces, well ... because they are just not familiar.
« Last Edit: 10/18/2014 04:54 PM by Rodal »

Tags: