Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1802089 times)

Offline Chrochne

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I like the idea because I actually think THAT the EMDrive IS a myth. And nothing else.

And it definitely should be the matter of Mythbusters and not of serious scientists.

I disagree. From the independent scientific level Dr. Rodal and the others here are actually very sceptic about the EmDrive. Still their research based on rigorous work is starting to show that there may be something into it. You have to understand that even after the years of claims that EmDrive works (claimed by Mr. Shawyer) the true research begun only just now ( from the time NASA EW and chinese folks showed their first results).

I learned here that too much shouting why it can and why it can not work leads to dead end only and proves nothing.

If the EM Drive turns out to be a valid form of propellant-less propulsion? Is it not also fair to also give credit where credit is due?

After all. Do you think that the first human that discovered the wheel could explain why it worked? Does that mean that there was ("as you say") no ("true research") by the original builder of the wheel, until the reasons why the wheel worked could be explained in full detail, by others?

After all. Even Newton was not 100 percent correct with all his known statements, Yet we still respect him on what he was correct about vs. trash talking him about what he was incorrect about.

Note: We as humans have been manipulating atoms in many ways, for many reasons and for many purposes, for some time now. However, only recently have we been able to determine why atoms have mass.

Don

Mr. Don,

Thank you for your reply. No worries I give credit to Mr. Shawyer.  And I do want EmDrive to work, as I said to Dr. Rodal several pages before. I have very good understanding of the international relations and EmDrive could well be the changer of the world in many good ways - but that is off topic and I do now want to elaborate on that. I just only want to see continuous work of all independent scientists, theorists and engineers here. It also gives hope :)

Of course if its do. We will have a great party on the flying hovercraft above the home of Mr. Shawyer :D

Now back to the shadows where I belong to.
« Last Edit: 07/17/2015 09:12 PM by Chrochne »

Offline Ricvil

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Just a thought.  ;D

It is just a ray trace realization of a resonant cavity with metamaterial inside ( n= -1; negative refraction index)
The result cavity shape is a tappered conical ( in 3D by revolution symmetry).
I1,I2,I3 and I4 are the images of point P (no diffraction idealization).
The metallic mirrors are to reflect back any ray from P point ( focal point inside metamaterial).
My doubt... what will be the result force in resonance?

Sounds like a job for MPD & Meep. I was thinking that the atomic dipoles of the metamaterial/dielectric will be in motion and subtract from the vacuum-mode reaction against the frustrum, but that doesn't seem to matter in fiber-optic gyros. I would think with using a gaseous or liquid masing/lasing medium the forces will go into merely stirring things up.

After absorbing Jayne's paper on  ghost modes in microwave waveguides, photonic crystals and Schrodinger-waves in semiconductors, and in light of apparent exhaust-less thrust being measured in phonon-dispersive Peltier devices, I can imagine a number of ways ratcheting could be created by energy, other than microwaves in a frustrum.

Since some of the most efficient generators of EM energy are magnetrons and klystrons, why not just fire an electron beam down a tapered-impedance (dispersive) slow-wave waveguide, so as to integrate the microwave generator and thruster into a single assembly? But again, there would be the reaction against the electron beam.

Axion electrodynamic too?  ;)

Online Rodal

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...
Good reading this AM has me leaning towards centered small base injection of the monopole because of what Shell said about the variety of insertion points yielding apparent results. ...

I would put the antenna near the small end, definitely not at the center.

We have:

A)  Todd (WarpTech) who described a theory as to why it is better to put the RF feed near the small end:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1373334#msg1373334

B) Paul March (NASA) with the drawing putting a magnetron at the very end of the small end, as the ideal design


C) Meep simulations showing that phase difference between ends is important to generate asymmetry, that taper and attenuation is important to generate asymmetry.  Why put the antenna at the middle which is the most symmetric place?  Ideally one wants the antenna at the place where it will generate the greatest asymmetry



D) In a regular antenna one has the feed at the small end, not at the middle or at the large end:





E) We have Todd's theory, Shawyer's theory, McCulloch's theory,


and Meep's FD simulations all remarking the importance of viewing the problem as one of travelling waves and not standing waves frozen in space.

« Last Edit: 07/17/2015 10:59 PM by Rodal »

Offline SeeShells

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Received my carbon fiber woven tubes. Very nice and very strong plus a few other things, a Raspberry PI and multiple attachments.

Will be out testing and learning.

Shell

Offline Blaine

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Hey Shell, you could recycle those after your experiments.  Basically, you wrap that in damp paper towel and magnesium strips to make a magnesium air batter.  Good luck with the EmDrive experiments, just something to do with them in case it doesn't work out for you.
Weird Science!

Online Rodal

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EM DRIVE FORCE vs. TIME

We continue the program started with posts

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1403629#msg1403629
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404000#msg1404000
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404004#msg1404004
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404005#msg1404005
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404006#msg1404006
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404754#msg1404754
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404783#msg1404783
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1405604#msg1405604
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1405605#msg1405605

showing the Force (Newtons) on the small and the big base vs. time and the net force ( (force on big base) - (force on small base)). 

The forces on the bases are obtained by numerical integration of the stress tensor σxx (*) component ( obtained using Wolfram Mathematica ( http://www.wolfram.com/mathematica/ ) , post-processed from the transient Finite Difference (using Meep) solution for RF feed ON for an EM Drive of the geometry of @rfmwguy (Db=11.01 in, Ds=6.25 in, L=10.2 in).

The stress component σxx  is compressive at both bases.  Therefore the force obviously points in different directions:  at the big base it points in the direction from the small base to the big base while at the small base it points in the direction from the big base to the small base.  From the interior to the surface in both cases.  In other words, the electromagnetic field exerts a pressure on both surfaces and the force points from the interior to the bases.

It is also very interesting to point out that:

1) The compressive force against the big base is larger (due to the greater surface of the big base) than the compressive force against the small base, even though the maximum stress at the small base is higher.

2) the time at which the maximum force occurs at the big base is phase-shifted with respect to the time at which the maximum force occurs at the small base.  The force at the small base leads, because the antenna is much closer to the small base than to the big base.

3) Notice that when the net force is at a minimum, it actually points for a very short amount of time towards the small base (positive direction). Most of the time it points towards the big base (negative direction).

4) We naturally expect that force on the overall copper itself should sum up to zero in order to satisfy the momentum equilibrium equation implied by Maxwell's equation.   We expect that the imbalance in net force between the bases should be compensated by the electromagnetic pressure on the lateral surfaces, leading to a component on the direction of the small base to result in a net overall force of zero.  We don't have access to the electromagnetic fields at the lateral surfaces computed by Meep, in order to calculate the stress tensor at the lateral surfaces and integrate it to get the force on the lateral surface.

5) It is still highly suggestive that there is a net force in the direction of the big base as a result of the imbalance between the big base and the small base, although the stress at the small base is higher, and although the stress distribution is completely different (as previously shown) at both bases.  Also, the Poynting vector is strongly pointing towards the big base (as previously shown).  If the EM Drive is not an experimental artifact, whatever is responsible for the acceleration must be using this net imbalance and phase shift between the forces at the bases  (for example:  plasma ions produced by microwave heating of the air inside the cavity, leaking out and producing an exhaust, or evanescent waves acting on air molecules, or electromagnetic pressure acting on axionic dark matter or on a degradable level of the Quantum Vacuum, etc.).  The net force imbalance between the bases, pointing towards the big base, is entirely consistent with a reaction acceleration of the EM Drive in the opposite direction as a result of a recoil force. 

6) A fitted model of the time variation of the force (with excellent R^2 = 0.999981), shows that the present Finite Difference model (from which the force has been computed at the last two cycles ending at 0.013 microseconds from the time at which the Microwave feed was turned on), would have to be marched forward for 1,000 times longer, to a total of 10 microseconds, for the force to be magnified by the calculated exponential growth to a value of 10 microNewtons (for an inputPower of 43 watts).   Given the fact that the present Meep model takes an hour to run on a good PC modern computer, 1,000 hours of computer time represents over 41 days of computing time.  Thus running the Meep model to steady state is impractical.  Rather than using a supercomputer to perform such a computation, I suggest to use an implicit (unconditionally stable) Finite (*****) Difference model in time (rather than the explicit time difference model presently used that is subject to stability problems that limit the maximum finite difference time step).  Such implicit finite difference models are well known (I developed a version of them in my PhD thesis 35 years ago) and can be run much faster than explicit FD models.  There are also numerous alternative numerical schemes that are more accurate than Finite Differences.

______________________________

NOTES:

Stress calculation:






(*)  (where we denote by σxx= T11 the contravariant component of the tensor acting along the longitudinal direction "x" of the EM Drive, normal to the the plane yz having normal x, where direction "1" is "x")

(**) For the copper diamagnetism is assumed such that the magnetization M is assumed proportional to the applied magnetic field such that for free space it is assumed that M is zero in free space in the relationship 

(***) The Stress calculations are for an Input Power of 43 Watts (similar to the value used by NASA in some of their runs).  The Stress values are proportional to the Input Power, so for example, if the Input Power were 860 Watts, that means that the calculated values for Stress are 860 Watts/ 43 Watts = 20 times greater than shown in the plots.    In other words, for 860 Watts InputPower, the values for Stress in the plots need to be multiplied by a factor of 20.  Ditto for the force.

(****) The total time from start of the RF feed in the Meep response analysis to the very last step is: 
 320 ( time slices) * 4.082199*10^(-11) seconds/timeSlice =
                                          = 0.013063 microseconds

Each "time slice" step is 4.082199*10^(-11) seconds/timeSlice

Duration of the total of 13 time slice steps = 53.068 *10^(-11) seconds

Last time step is at 0.013063 microseconds from the start of the RF feed ON


___________________________________________________________
Conversion to get SI Units from the graphs and equations in Meep units:

TIME:  Multiply Meep Time Slice "t" in the horizontal axis and in the formulae by the following factor:

((Total Meep Time)/(#Time Slices))*((Length Scale Factor)/(Speed of Light in Vacuum)) =
                                                                                                           =((13.054)/(320))*((0.3)/(299792458))
                                                                                                           =4.082199*10^(-11) seconds/timeSlice



ASSUMPTIONS: the validity of the following data:

Number of time slices for the total run = 320
Number of Meep time units for the total run = 13.054
Meep Length Scale factor= 0.3 meters
Meep Current (Io) = 1


(*****) One of the earliest unconditionally stable, implicit time domain methods was developed by John Houbolt  (https://en.wikipedia.org/wiki/John_Houbolt ) at NACA (predecessor of NASA) in 1950:

.J. C. Houbolt, ‘A recurrence matrix solution for the dynamic response of elastic aircraft’, J. Aeronaut. Sci., 17,540-550, (1950).

, the same Houbolt who had the genius to create the Lunar orbit rendezvous method to land astronauts on the moon with a single Saturn V, and prevail over Von Braun's Nova rocket concept (eventually von Braun came around and supported Houbolt's proposal).   It was due to Houbolt's concept  that the US was able to reach the Moon by 1969.

« Last Edit: 07/18/2015 02:20 AM by Rodal »

Offline TheTraveller

How bout that I know and have met and worked on air bearings, powered and not, with my design projects? How about working with the Load Point engineers and the VP of engineering back when the were called WestWind and even after they changed?

I'm quite aware of who they are.

Shell

Glad to know that. Shawyer did likewise and as a senior UK aerospace engineer, funded by the UK gov, had assistance to make sure the SPR air bearing build had no issues. Watching the long video it is clear there is no movement of the 100kg mass on the air bearing until the magnetron finds cavity resonance lock and then it begins to slowly accelerate, which can be see from the Velocity curve. Once the magnetron is switched off, it stops moving.

This is not a marble in an air stream velocity curve, that just happens to start at 130 sec but nothing before.
« Last Edit: 07/18/2015 02:04 AM by TheTraveller »
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Offline TheTraveller

I'm excited.

Found Prof Yang has achieved my long term goal of 1N/kW as attached.

More good news is my friend who found the 100W Rf amp, is arranging to have my EMDrives manufactured in China, to my specs (2mm thick OFC side walls and spherical end plates to +-0.05mm), including being highly optically polished inside, O ring seals and N2 filled to stop oxidation. I will, at first, still need to install the 3 x spherical antenna array.

When I'm ready to try out internal silver plating, my friend can arrange that as well.

I'm excited!!!
« Last Edit: 07/18/2015 02:26 AM by TheTraveller »
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Online Rodal

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SeeShells: notice

<< to my specs ... O ring seals and N2 filled >> chirality and nitrogen inversion at room temperature

Add some ammonia for a Maser effect.
« Last Edit: 07/18/2015 03:04 AM by Rodal »

Offline TheTraveller

SeeShells: notice

<< to my specs ....and N2 filled >> chirality and nitrongen inversion at room temperature

Pure N2 in my cavity can convert to chiral molecules???????????

Sure Ammonia can do this trick but pure N2?
https://en.wikipedia.org/wiki/Nitrogen_inversion
« Last Edit: 07/18/2015 02:48 AM by TheTraveller »
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Offline TheTraveller

SeeShells: notice

<< to my specs ....and N2 filled >> chirality and nitrongen inversion at room temperature

Pure N2 in my cavity can convert to chiral molecules???????????
Are you using polymer O Rings ?

Was planning on using space qualified (no outgassing) silicon O rings.
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Offline mwvp

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I can imagine a number of ways ratcheting could be created by energy, other than microwaves in a frustrum.

Axion electrodynamic too?  ;)

Why not. Need some equivalent of Maxwell Eq. for the Axion field and coupling constant to the EM field.
Maybe nuclear forces are dispersive; that could save a lot of bother. Red Mercury?  ;D

Offline mwvp

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B) Paul March (NASA) with the drawing putting a magnetron at the very end of the small end, as the ideal design


I like it. Like Yang's test, he's got a tuned cavity to stabilize and narrow the magnetron bandwidth, and a small aperture to impedance match to the frustrum. And I suspect there may be the benefit of added group delay (for low velocity or acceleration), kind of like having a transmission with a low-gear. The aperture would be dilated for increased coupling, reduced impedance and increased BW for better efficiency - high-gear.
« Last Edit: 07/18/2015 04:49 AM by mwvp »

Offline mwvp

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FYI, waveguide design info:

A great resource is the ancient and venerable MIT Radiation Laboratory Series;

https://www.jlab.org/ir/MITSeries.html
The index -  https://www.jlab.org/ir/MITSeries/V28.PDF
Vol 10 Waveguides: https://www.jlab.org/ir/MITSeries/V10.PDF

Also scribd.com; you can get a free 2 week account so you can download stuff.

Offline TheTraveller

B) Paul March (NASA) with the drawing putting a magnetron at the very end of the small end, as the ideal design


I like it. Like Yang's test, he's got a tuned cavity to stabilize and narrow the magnetron bandwidth, and a small aperture to impedance match to the frustrum. And I suspect there may be the benefit of added group delay (for low velocity or acceleration), kind of like having a transmission with a low-gear. The aperture would be dilated for increased coupling, reduced impedance and increased BW for better efficiency - high-gear.

Just maybe each of the 20 x 100kW EMDrives on the IXS Clark are modeled on that design. Nice redundancy, 1 x 100kW magnetron per EMDrive pod.

Like it.
« Last Edit: 07/18/2015 08:50 AM by TheTraveller »
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Offline deltaMass

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The name is Clarke.

Sir Arthur C. Clarke.


Online Stormbringer

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Weyl fermions; massless particle found.

http://phys.org/news/2015-07-year-massless-particle-next-generation-electronics.html

how many more of these sorts of things are there out there?
When antigravity is outlawed only outlaws will have antigravity.

Offline TheTraveller

The name is Clarke.

Sir Arthur C. Clarke.

Here is my IXS Doable:
5 x BA330s, 3 x D2 taxis, 2 x spare docking ports, 1,650m3 of pressurised volume, 80% more than the ISS. Not as pretty as IXS Clarke but much more Doable and buildable now.

IXS Clarke image attached.
« Last Edit: 07/18/2015 08:52 AM by TheTraveller »
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Offline deltaMass

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Fission reactor? Heat radiators? Why use any fuel at all? Just power the main engines with a rotary overunity EmDrive power unit  8)

Offline TheTraveller

Fission reactor? Heat radiators? Why use any fuel at all? Just power the main engines with a rotary overunity EmDrive power unit  8)

What I think is we don't know what rules will apply but there will not be any overunity.

What I see in this measured example, attached, is magnetron Power usage dropping, while Velocity increases. Note I copied the Velocity curve, inverted it and placed it under the Power curve. Close match. Suggest this data is trying to tell us something about an area of physics we have almost no experimental data on.
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