Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1876216 times)

Offline Rodal

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I'm shooting for TE112 first shot but meep is a little lacking using an antenna other than the placements. Have a few ideas other than just throwing the antenna in the cavity.

Wasn't aero going to try to excite a mode in the side wall with a snub center to top and bottom today with the itsybitsy cavity? It was also suggested that a square pad could be made simulating a loop that could excite a TE mode, wonder what happened to that line of thought?

Thanks for the feedback, it was helpful.

Shell
Did you notice my post where I wrote that the Wolfram Mathematica / Meep runs reveal that SeeShells was right that having the lateral antenna at the big end is better than at the small end for Yang/Shell?

Unfortunately so far we only know this for TM modes (since TE modes cannot be excited by a dipole antenna).  aero is running rfmwguy with the antenna at the big end.  We'll see whether what we found for Yang/Shell is also the case for NSF-1701.

____

PS: I thought you were shooting for TE012 instead of TE112. 
« Last Edit: 07/28/2015 01:13 AM by Rodal »

Offline rfmwguy

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Spaceflight. I've avoided useage of the term without enough ground test results, but it might be time to plant a seed of discussion for the future considering Tajmar's paper. We will need to think about electric power for a smallsat. That will not be easy.

A magnetron is not 100% efficient, meaning that this type of device would require north of 1kW of electric power. This is not easily attainable on a satellite. RTGs are usually much below this.:

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Solar panels appear to be the best choice at levels above 1kW:

https://en.wikipedia.org/wiki/Solar_panels_on_spacecraft

So dreams of deep space travel might look like this: Solar Panels to ? AU, jetison, then RTG takeover when out of solar influence. IOW, a hybrid power design.

Moral of story, optimize for max performance to weight ratio/effeciency. Partner with solar panel and/or RTG provider.

Agreed on solar power for inside the asteroid belt. However, What do you think abuot fuel cells?
A little unclear on those babies. You might have to upskill me a bit. ;)

Offline SeeShells

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...

...
I'm shooting for TE112 first shot but meep is a little lacking using an antenna other than the placements. Have a few ideas other than just throwing the antenna in the cavity.

Wasn't aero going to try to excite a mode in the side wall with a snub center to top and bottom today with the itsybitsy cavity? It was also suggested that a square pad could be made simulating a loop that could excite a TE mode, wonder what happened to that line of thought?

Thanks for the feedback, it was helpful.

Shell
Did you notice my post where I wrote that the Wolfram Mathematica / Meep runs reveal that SeeShells was right that having the lateral antenna at the big end is better than at the small end for Yang/Shell?

Unfortunately so far we only know this for TM modes (since TE modes cannot be excited by a dipole antenna).  aero is running rfmwguy with the antenna at the big end.  We'll see whether what we found for Yang/Shell is also the case for NSF-1701.

____

PS: I thought you were shooting for TE012 instead of TE112.
No I didn't see it, sorry I missed chunks, was a little preoccupied.  I'll go back and review it.

my bad you're right digit malfunction TE012.


Offline Rodal

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I show the calculated TE111 Electric Field in theta polar direction for Tajmar's TU Dresden University EM Drive, to compare it with his COMSOL FEA calculation

Assumed dimensions:


Big diameter = 0.1062 m = (2*0.0541m - 0.002 m)
Small diameter = 0.075 m = (2*0.0385 m - 0.002 m)
Axial Length = 0.100842 m =  0.735*2*0.0686 m

As per TheTraveller I have subtracted 2 mm for copper thickness from the external dimensions, however this has a negligible influence on the results

The axial internal length is 73.5% of the exterior length (it is adjusted internally with a screw prior to testing)

TE111 Natural frequency = 2.446 GHz

I enclose strictly for discussion, research and illustration purposes Fig. 2 a of Tajmar et.al. COMSOL FEA analysis for comparison with my calculations


 “…for purposes such as criticism, comment, news reporting, scholarship, or research…” under US Fair Use

http://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/

This is the  American Institute of Aeronautics and Astronautics link to Martin Tajmar's et.al. paper, that should be obtained from the American Institute of Aeronautics and Astronautics:

Direct Thrust Measurements of an EM Drive and Evaluation of Possible Side-Effects  M. Tajmar and G. Fiedler
51st AIAA/SAE/ASEE Joint Propulsion Conference

http://arc.aiaa.org/doi/pdf/10.2514/6.2015-4083

I show the calculated TE111 Electric Field in theta polar direction for Tajmar's TU Dresden University EM Drive, to compare it with his COMSOL FEA calculation

Using Tajmar's dimensions as per his paper:

Big diameter = 0.0521 m = (0.0541 - 0.002) m
Small diameter = 0.0365 m = (0.0385 - 0.002) m
Axial Length = 0.0666 m =   (0.0686 - 0.002) m

bigDiameter = ; smallDiameter =; axialLength = (0.0686 - 0.002);

As per TheTraveller I have subtracted 2 mm for copper thickness from the external dimensions, however this has a negligible influence on the results

TE111 Natural frequency = 4.556 GHz

Notice that the electric field using the smaller dimensions in the paper is out of phase and that the natural frequency is practically twice as high than the exciting frequency

______

I also show for comparison, the previous calculation using the dimensions that are two times the dimensions in the paper

the comparison clearly shows that Tajmar's EM Drive dimensions were twice the printed dimensions, a major error in the paper presented to the AIAA.  This was first brought up by X-Ray, and further elaborated by TheTraveller and Todd "WarpTech"
« Last Edit: 07/28/2015 01:45 AM by Rodal »

Offline demofsky

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Spaceflight. I've avoided useage of the term without enough ground test results, but it might be time to plant a seed of discussion for the future considering Tajmar's paper. We will need to think about electric power for a smallsat. That will not be easy.

A magnetron is not 100% efficient, meaning that this type of device would require north of 1kW of electric power. This is not easily attainable on a satellite. RTGs are usually much below this.:

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Solar panels appear to be the best choice at levels above 1kW:

https://en.wikipedia.org/wiki/Solar_panels_on_spacecraft

So dreams of deep space travel might look like this: Solar Panels to ? AU, jetison, then RTG takeover when out of solar influence. IOW, a hybrid power design.

Moral of story, optimize for max performance to weight ratio/effeciency. Partner with solar panel and/or RTG provider.

Agreed on solar power for inside the asteroid belt. However, What do you think abuot fuel cells?
A little unclear on those babies. You might have to upskill me a bit. ;)

Ok, this is a topic that at some point probably is worth its own thread, once we get a bit more signal from the experiments.  (And avoid polluting this august thread with grimy talk of space flight! ;D )

In a nutshell, the whole EM drive thing is coming at an interesting time in the evolution of space exploration architectures.  What folks are starting to realize is that it is optimal for current rocket technology to raise payloads into LEO and for solar electric drive tugs to move the payloads from that point on.  Very interesting.

The whole idea of using rockets to boost payloads all the way to Mars, etc. is having space cleared for it alongside the buggy whip displays.

The thing about solar electric drive tugs going out to Mars is that they have to lug propellant (typically Xenon) and that reduces the payload capacity.  Have to find the link to the folks who did the study, but the propellant amounts were surprisingly large when you want to move like 100 tons - as always, the standard rocket equation applies.

If we can get EM Drives working at even half the efficiency of your basic ion drive there will be huge wins for the new space exploration architecture.  Not only in payload capacity but also in transit times. 

The major trade now becomes how much solar arrays you want to tack on to these things.  I have seen a Boeing study where they looked at tugs with 1 MW and more (5 MW?) arrays.  You could look at the solar arrays as a form of propellant but really it is an investment that can be amortized over many transits unlike propellants.

@birchoff - fuel cells basically mean you have introduced propellants into a propellantless system.  This only makes sense if you can use the energy density to lift something out of a gravity well like a rocket.

Edits: clarification.
« Last Edit: 07/28/2015 02:11 AM by demofsky »

Offline A_M_Swallow

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Agreed on solar power for inside the asteroid belt. However, What do you think abuot fuel cells?

Fuel cells may have a use for powering aircraft on oxygen free places like Venus.
« Last Edit: 07/28/2015 01:59 AM by A_M_Swallow »

Offline demofsky

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Agreed on solar power for inside the asteroid belt. However, What do you think abuot fuel cells?

Fuel cells may have a use for powering aircraft on oxygen free places like Venus.

NASA studies are looking at solar even for that.  Admittedly, high altitude aircraft.  Lower down the pressure, temperature and corrosiveness mean that a power source is probably the least of your problems! :)

Offline aero

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@SeeShell
Quote
Wasn't aero going to try to excite a mode in the side wall with a snub center to top and bottom today with the itsybitsy cavity? It was also suggested that a square pad could be made simulating a loop that could excite a TE mode, wonder what happened to that line of thought?

I've been holding off on that. As has been explained, the itsybitsy cavity cannot resonate at 2.45 GHz. I concur as meep images show nothing but scattered energy in the cavity at that size and frequency. Instead, it resonates well at twice the dimensions with length adjusted. See Rodal's posts.

I can model either set of dimensions and put dipole or point source antennas wherever you'd like but ... will we benefit from exploring that cavity before we get more firm information about the dimensions?

As for the square pad idea, I think that was notarget, not sure. And I'm not sure how to do that myself because I don't know how meep code treats current sources and geometric objects together. I do know that it does not track the electrons.

aero
Retired, working interesting problems

Offline deltaMass

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Spaceflight. I've avoided useage of the term without enough ground test results, but it might be time to plant a seed of discussion for the future considering Tajmar's paper. We will need to think about electric power for a smallsat. That will not be easy.

A magnetron is not 100% efficient, meaning that this type of device would require north of 1kW of electric power. This is not easily attainable on a satellite. RTGs are usually much below this.:

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Solar panels appear to be the best choice at levels above 1kW:

https://en.wikipedia.org/wiki/Solar_panels_on_spacecraft

So dreams of deep space travel might look like this: Solar Panels to ? AU, jetison, then RTG takeover when out of solar influence. IOW, a hybrid power design.

Moral of story, optimize for max performance to weight ratio/effeciency. Partner with solar panel and/or RTG provider.
I'm a fan of a web of beamers. These are high power solar-powered lasers and the beams crisscross the solar system. They are of course dynamically steerable. It is like laying down an infrastructure of tramlines. They enable both acceleration and braking. They would greatly help in opening up interplanetary space.

Offline aceshigh

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The device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al.  It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...

<clip>
So if you or one of your friends within that 50 mile radius want to put a couple bucks to help not to make more millions but because they choose to dream, I'll welcome it.

Shell

I am game. Maybe you can get a kickstarter togetger. I would contribute and I am sure more people would too
It's at the bottom of my post under Crazy Eddie is getting a little more crazy. ;)

Thank You!!

Love that signature. So related to EM Drive.

On one hand we have Shawyers nonsensical theory. On the other hand, Dr White's very controversial QVF explanations, which imho seems like he tries to fit any experiment into it.

On the gripping hand, the validity of the measured effects is EMs salvation...

Offline demofsky

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Agree about water.  I have encouraged experimenters to track the humidity around their rigs.  Humidity can be very high at this time of year (unless you are on the west coast :) ).

Offline LasJayhawk

Random thoughts:

A microwave oven Maggie, operating at 200C in a vacuum may out gas from its radiator. This could cause the appearance of something that looks like working mass, but isn't.

Once again, the Edison Effect predates the discovery of the electron by over a decade. Who knows what we could be spitting out the business end... :)

Has anyone considered a fractal antenna, to try and maximize the power dumped into the frustum?

Offline Rodal

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« Last Edit: 07/28/2015 02:53 AM by Rodal »

Offline SeeShells

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Agreed on solar power for inside the asteroid belt. However, What do you think abuot fuel cells?

Fuel cells may have a use for powering aircraft on oxygen free places like Venus.
http://www.lockheedmartin.com/us/products/compact-fusion.html

Lockheed Martin: Compact Fusion Research & Development at the Skunk Works is working on this and since we're talking about future tech I think this would scale quite well to space.

Offline DrLOAC

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2 comments I'd like to make:

First: Solar power.  The ISS arrays are about as big as you would want to build. With 80's solar cells they are good for about 30KW at 1 AU and beginning of life. The latest cells are about 3 times more efficient. If you used the same size arrays with the latest high efficiency cells you could eek out maybe 90-100KW per array or roughly 3/4 of a MW for something ISS sized. If you are in orbit, battery charging for night passes reduces usable power by over half. The arrays tend to be rather fragile as well.

I think I'd rather hook an EM drive up to a nuclear reactor.

Second
If Dr. White is correct about pushing on virtual particle pairs, I was wondering the following. 

In one of his speeches I remember him saying that micro-electrical machines had to be designed with casmir forces in mind otherwise they wouldn't work correctly.

If the EM drive does manipulate virtual particles wouldn't it be possible so set up an array of pressure sensitive MEMs to see if the Casmir force changes while the drive is in operation?

If you accounted for any other electromotive, magnetic or emf forces a change in Casmir force should be pretty definitive. Although this is not my area of expertise.

« Last Edit: 07/28/2015 03:25 AM by DrLOAC »

Offline demofsky

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Agreed on solar power for inside the asteroid belt. However, What do you think abuot fuel cells?

Fuel cells may have a use for powering aircraft on oxygen free places like Venus.
http://www.lockheedmartin.com/us/products/compact-fusion.html

Lockheed Martin: Compact Fusion Research & Development at the Skunk Works is working on this and since we're talking about future tech I think this would scale quite well to space.

There are other promising fusion projects that might fit the bill as well.  The question here is how well will a particular approach scale down to 5-10 MW?  The Lougheed approach does not have direct energy conversion so you need the standard turbines, etc. 

That said, the main thing is once you get something into orbit that is reliable you get a lot of amortization...

It will be interesting to do the trades on the different approaches.  Solar cells are a surprisingly strong alternative - especially to someone who strongly assumed you would need something nuclear for these power levels.

Offline deltaMass

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I've now read Tajmar's paper and I find, like him, the conclusions not to be clear, crisp and unambiguous, but rather murky and confusing. As usual we have the problems when batteries are not used, and thus you cannot self-contain the whole rig, and you need Galinstan, yadda yadda. This really shouldn't be necessary - the entire apparatus (batteries, power supply electronics and device) should be in one box with no trailing wires and connections.

Then there's the issue of "thrust" remaining after the power is disconnected. With a Q of only 50 there is no question of retention of state by the cavity. This must be thermal. But disappointingly, it is of the same magnitude as "thrust" itself. A very poor signal-to-thermal noise ratio.

The chief ray of sunshine is the thrust reversal.

Also, as I mentioned before, there's "horizontal thrust" measured at right angles to the expected thrust direction, and since the waveguide is so fat, that may be due to essentially opening up a second asymmetric cavity.

All in all, a very murky picture.
« Last Edit: 07/28/2015 03:47 AM by deltaMass »

Offline SeeShells

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Random thoughts:

A microwave oven Maggie, operating at 200C in a vacuum may out gas from its radiator. This could cause the appearance of something that looks like working mass, but isn't.

Once again, the Edison Effect predates the discovery of the electron by over a decade. Who knows what we could be spitting out the business end... :)

Has anyone considered a fractal antenna, to try and maximize the power dumped into the frustum?
Yes a fractal antenna would be a great device to use but normally the ones I've seen have been small and limited in transmitted power. Do you know of larger that could take 1000 watts?

Shell

Offline demofsky

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2 comments I'd like to make:

First: Solar power.  The ISS arrays are about as big as you would want to build. With 80's solar cells they are good for about 30KW at 1 AU and beginning of life. The latest cells are about 3 times more efficient. If you used the same size arrays with the latest high efficiency cells you could eek out maybe 90-100KW per array or roughly 3/4 of a MW for something ISS sized. If you are in orbit, battery charging for night passes reduces usable power by over half. The arrays tend to be rather fragile as well.

I think I'd rather hook an EM drive up to a nuclear reactor.
....

This is exactly what I would have expected.  Remember though that EM (and other electric) Drives are very gentle so it does not matter if a tug uses massive (monstrous?) arrays that are fragile.  This thing will change course slowly and things will not fly off.  They use chemical rockets on the ISS and so the stress is much higher.

Edits:  Clarification.
« Last Edit: 07/28/2015 03:54 AM by demofsky »

Offline DrLOAC

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2 comments I'd like to make:

First: Solar power.  The ISS arrays are about as big as you would want to build. With 80's solar cells they are good for about 30KW at 1 AU and beginning of life. The latest cells are about 3 times more efficient. If you used the same size arrays with the latest high efficiency cells you could eek out maybe 90-100KW per array or roughly 3/4 of a MW for something ISS sized. If you are in orbit, battery charging for night passes reduces usable power by over half. The arrays tend to be rather fragile as well.

I think I'd rather hook an EM drive up to a nuclear reactor.
....

This is exactly what I would have expected.  Remember though that EM (and other electric) Drives are very gentle so it does not matter if a tug uses massive (monstrous?) arrays that are fragile.  This thing will change course slowly and things will not fly off.  They use chemical rockets on the ISS and so the stress is much higher.

Edits:  Clarification.

Well for attitude control a tug may have more powerful attitude control thrusters. So rates have to be kept down. You also have to be concerned about environments. Atomic oxygen and RCS thruster exhaust can damage or pit cell coverings reducing power generation over time.

Finally you have to be concerned about thermal loading. The mast structure has to be flexible to deploy which can leave it susceptible to buckling when thermal stresses are coupled with mechanical stresses from maneuvers.

It's not that it can't be done, it has already on the ISS, its just more of a pain in the butt than you might think.

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