Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797951 times)

Offline WarpTech

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I'm experiencing a complete disconnect from what you're doing here. Looking at the input side, which is a battery carried along for the ride - not external, please note - you state
Pin  = dm/dt c2

This says that the battery loses rest mass. That is true, but it is absolutely a tiny mass even over long periods of time, compared with the total rest mass of the device. How is this expected to "save overunity"?

Tell you what - prove it to yourself. Use the numbers I used before (1000 gee, 1 m radius, 100 m/s to my energy breakeven) and recalculate using your dm stuff. I guess you will not see any substantive difference.

My derivation of energy breakeven has been posted here several times. Tossing in some minuscule dm will not make any substantive difference. But you are welcome to go through it line by line and post your version.

If the battery and stored energy is on board the vehicle, that makes it easier. It will run out of fuel before it can go over unity.
Todd

Offline SeeShells

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Random thought alert...we've been promised life-changing inventions before like the segway and taco bell home delivery. Yes, they are real; theories have been formulated  agreed upon, yet they are never really life-changing in reality.

What we are struggling with here is a real life-changing proposal...interstellar access and down to earth applications. Before we get too critical or demotivational, consider the what-ifs and temper negativity in lieu of the grand potential. We only have a few of these opportunities in a lifetime.

Just a friendly suggestion.
I for one realize what is on the table here and I'm not alone. Amazon deliveries by EMDrone and Taco Bell in minutes wizzin to your door for those with the munchies and can't drive! Sometimes the un-creativity of the human species scares me a little.

I'm going to strive to make a better use of this opportunity.

Shell

Offline Slyver

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Running with the “inertial ratchet” idea, it could be that air pressure plays a part in the observed force exerted by the frustum. Assuming this means that the effective inertial mass (resistance to acceleration) is less in one direction than the other:

--With an EMdrive's longitudinal axis aligned along the x direction (using parentheses as subscript, not “function of”)
--Assuming a big side radius of 0.1m (and assuming the same effective radius on the small side with regard to air pressure), air pressure of 101325N/m^2 (1atm), EMdrive weight = 1kg

F(x,big) = m(big)a(big) = 101325N/m^2 (pi) (0.1m)^2 = 3183.2N = 1kg (3183.2m/s^2)

F(x,sm) = m(sm)a(sm) = -101325N/m^2 (pi) (0.1m)^2 = -3183.2N = 1.0001kg (-3182.9m/s^2)

a(net) = 3183.2 + -3182.9 = 0.3m/s^2 (towards the sm end)

F(net) = 1kg (0.3m/s^2) = 0.3N

So by this overly simplified model based on the inertial ratchet axiom, a 1kg EMdrive creating an effective mass differential of 0.01% would exert a force of 0.3N on a scale due to external air pressure.

I only expounded on this idea because of the much lower force data we have for vacuum experiments (and because I think the idea is really cool, even if it proves to have no merit). The forces measured in vacuum might be due to vibrations in the system*, which are presumably intentionally minimized.

* which would also produce a force towards the effective smaller mass side as elucidated earlier
« Last Edit: 07/09/2015 03:43 AM by Slyver »

Offline DrBagelBites

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Random thought alert...we've been promised life-changing inventions before like the segway and taco bell home delivery. Yes, they are real; theories have been formulated  agreed upon, yet they are never really life-changing in reality.

What we are struggling with here is a real life-changing proposal...interstellar access and down to earth applications. Before we get too critical or demotivational, consider the what-ifs and temper negativity in lieu of the grand potential. We only have a few of these opportunities in a lifetime.

Just a friendly suggestion.
I for one realize what is on the table here and I'm not alone. Amazon deliveries by EMDrone and Taco Bell in minutes wizzin to your door for those with the munchies and can't drive! Sometimes the un-creativity of the human species scares me a little.

I'm going to strive to make a better use of this opportunity.

Shell

"EMDrones: Both delivering and heating up your food" I think you are on to something. ;)

I know it's off-topic, but it was too good to pass up.
« Last Edit: 07/09/2015 02:56 AM by DrBagelBites »

Offline SeeShells

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Random thought alert...we've been promised life-changing inventions before like the segway and taco bell home delivery. Yes, they are real; theories have been formulated  agreed upon, yet they are never really life-changing in reality.

What we are struggling with here is a real life-changing proposal...interstellar access and down to earth applications. Before we get too critical or demotivational, consider the what-ifs and temper negativity in lieu of the grand potential. We only have a few of these opportunities in a lifetime.

Just a friendly suggestion.
I for one realize what is on the table here and I'm not alone. Amazon deliveries by EMDrone and Taco Bell in minutes wizzin to your door for those with the munchies and can't drive! Sometimes the un-creativity of the human species scares me a little.

I'm going to strive to make a better use of this opportunity.

Shell

"EMDrones: Both delivering and heating up your food" I think you are on to something. ;)

I know it's off-topic, but it was too good to pass up.

No it's perfect, a chuckle and smile are always on topic. ;D

Offline deltaMass

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...
I'm experiencing a complete disconnect from what you're doing here. Looking at the input side, which is a battery carried along for the ride - not external, please note - you state
Pin  = dm/dt c2

This says that the battery loses rest mass. That is true, but it is absolutely a tiny mass even over long periods of time, compared with the total rest mass of the device. How is this expected to "save overunity"?

Tell you what - prove it to yourself. Use the numbers I used before (1000 gee, 1 m radius, 100 m/s to my energy breakeven) and recalculate using your dm stuff. I guess you will not see any substantive difference.

My derivation of energy breakeven has been posted here several times. Tossing in some minuscule dm will not make any substantive difference. But you are welcome to go through it line by line and post your version.

If the battery and stored energy is on board the vehicle, that makes it easier. It will run out of fuel before it can go over unity.
Todd
Ahem. I thought we were discussing EmDrive, which is a propellantless vehicle. There is no exhaust. The onboard battery provides constant power Pin. The output power is pure kinetic. Ergo your calculation makes no sense when applied to the EmDrive.

Offline dumbo

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The meep results obtained by aero and Dr. Rodal are very suggestive! It would be nice if someone could run the simulation over more cycles; if the Poynting vector growth over time is observed to follow the extrapolations produced by Dr. Rodal, then it would make the case even stronger. Also, how might the fears that this is all an artifact of the numerical simulation process be assauged?

EDIT: pointing -> Poynting, interpolations -> extrapolations
« Last Edit: 07/09/2015 03:34 AM by dumbo »

Offline deltaMass

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By posting something that did not contain the phrase ***UNDER CONSTRUCTION***, I am told.  :P

Offline WarpTech

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Sooooo..... the Poynting vector has a DC offset eh? Who would've thought that! LOL!

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1041397

This means E and H should have a DC component as well, which means there are probably DC circulating currents around the frustum as it's charging.

At least that is how I would interpret these extrapolations and the uni-directional poynting vector.
Todd

Offline dumbo

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By posting something that did not contain the phrase ***UNDER CONSTRUCTION***, I am told.  :P

Right, now in the (hypothetical) event that more meep data is produced showing results similar to the *** UNDER CONSTRUCTION *** curves by Dr. Rodal, what is to prevent someone from claiming that this is all "clearly" false still? What kind of proof would be acceptable to a skeptic that the meep data is not spurious? I am asking you this since, while everyone does seem to acknowledge the limits of numerical modelling, you are the only one who seems to feel that meep data is a priori invalid.

Offline WarpTech

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...
I'm experiencing a complete disconnect from what you're doing here. Looking at the input side, which is a battery carried along for the ride - not external, please note - you state
Pin  = dm/dt c2

This says that the battery loses rest mass. That is true, but it is absolutely a tiny mass even over long periods of time, compared with the total rest mass of the device. How is this expected to "save overunity"?

Tell you what - prove it to yourself. Use the numbers I used before (1000 gee, 1 m radius, 100 m/s to my energy breakeven) and recalculate using your dm stuff. I guess you will not see any substantive difference.

My derivation of energy breakeven has been posted here several times. Tossing in some minuscule dm will not make any substantive difference. But you are welcome to go through it line by line and post your version.

If the battery and stored energy is on board the vehicle, that makes it easier. It will run out of fuel before it can go over unity.
Todd
Ahem. I thought we were discussing EmDrive, which is a propellantless vehicle. There is no exhaust. The onboard battery provides constant power Pin. The output power is pure kinetic. Ergo your calculation makes no sense when applied to the EmDrive.

The paradox with propellant driven space craft was explained too, by Dr. White. It occurs anytime "constant acceleration" is assumed, without taking into account the variables in the av(t) expression I posted. In the case of the EM drive where there is no exhaust, dm/dt is replaced by the change in potential energy from the small end, to the big end, per unit time, /c2.

And BTW, if the EM drive were to store every bit of energy put into it, with a high power source it would have to explode eventually. The energy either needs to escape, generate heat or move the thing in order to dissipate. Or else the source input will eventually become saturated until nothing more will go in.
Todd

Offline TheTraveller

Due to the higher cost and reduced availability of 3.85GHz Rf amplifiers, I've decided to switch my build to 2.45GHz.

I've designed a version of the Flight Thruster that works at TE013 @ 2.45GHz. Build will look like the Flight Thruster, just bigger.

Specifications:

Big end: 400.0mm,

Small end: 148.7mm,

Length: 267.5mm,

Df: 0.9249,

Rf: 2.45GHz via 3 coax feeds,

20W via isolator,

Designed Q 100,000,

Predicted Force generation: 12.34mN or 1.26gf @ 20W as per attached screen shot of my spreadsheet.

Possibility to silver polish electroplate with thin gold over flash to eliminate silver oxidation,

Spherical end plates,

O ring seals at each end,

2mm thick cone side walls,

5mm thick flanges at each end of the cone,

Flanges to cone and cone side wall butt seam will be silver soldered for good electrical conductivity and strength,

Ability to run at reduced atmo pressure on N2 backfill via air valve in cone side wall,

All inside surfaces ding & scratch free, highly polished.

Antenna is 3 x 1/4 wave elements joined together at the centre & fed via 3 cone wall located coax connectors, with the antenna curved to match the spherical EM wave at 1/4 wave from big end.

Plan to do all the machining myself, ordering a new lathe. I've worked in machine shops since 10 and feel very capable of doing the machining to better than +-0.1mm.

Will test on a cordless rotary test rig that can turn for as long as the batteries last. Crude drawing attached. Hope you can understand it.

Once the design is proven, I plan to offer EMDrives for sale, at my material cost, to anyone who can show me they have built my rotary test rig, Rf and data collection system.

Idea is to have many Force generation verifiers all over the planet and to forever stop any doubts about the EMDrive.

My son is a dual honours graduate in Software Engineering and Physics. He lectures at the local uni. We think we can convince the Physics Dept to engage with the testing program and produce a paper on the results and maybe get it peer reviewed.
« Last Edit: 07/09/2015 04:17 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline lmbfan

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Aero, would it be possible to share your Meep files, along with a write-up on scripts and commands used to generate the data, so that other meepsters can help out and/or replicate the data?  A consistent format for outputting csv/png/hdf5 files would speed analysis.

Dr. Rodal, would it be possible to share you Matlab techniques, scrpits, and/or other methods of extracting the Poynting vectors? Again, for helping out and replication.

Offline zellerium

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On the topic of magnetrons,

although they aren't a perfect rf source, they are the most feasible option for anyone doing a DIY experiment. Getting a 1 kW source for $20 is a bit unbelievable when you consider renting a 500 W amp for $3,000/month. There are cheaper methods of obtaining a high power amp, but from my experience they seem unreliable.
 
Yes, the power isn't evenly distributed and the BW is ~60 MHz, but this can be sharpened for the relatively cheap price of metal to create intermediate resonant cavity and high power coax. And keeping the core temperature steady should prevent frequency drifting, correct?  So IMO, using low power, narrow BW amps is going to make it more difficult to get a 5 sigma deviation from noise unless you have something equivalent to a low-thrust torsion pendulum.

We have recently been dealing with the issue of replicating a magnetron output using the VNA. So today I cut open magnetron to expose the coupling wire used to transfer energy from the resonant cavity to the antenna. It looks like the antenna used consists of the coupling wire pinched in a copper tube, housed in a stainless steel cylindrical cavity.
 
To replicate the antenna, we're thinking of sacrificing another magnetron the cut out the full length of coupling wire, and soldering a BNC-to-wire connection. Then we can approximately simulate a magnetron output and measure reflected power to determine positions of resonance for our adjustable, partially loaded cavity.   

Also, I noticed many people are opting for a laser measurement system. I think this method is ideal, especially if you can track the laser effectively. We were able to borrow a PSM2-10 Position Sensing Module which apparently has 0.0000 mm resolution. However, we don't know how much noise will be present so our actual resolution is TBD.

Kurt
Hey kurt...might humbly suggest an N or mini DIN at these freqs and power levels...had some bad experience at 1kw and bncs...not pretty.

Scope out this chart: http://www.hamradio.me/graphs/connectors/UHFConnectorGraphs/Insertion-Loss_S21_1000.png

The BNC connector is what the vector network analyzer uses, which we will hook up to our 'mock' magnetron antenna (ie the copper wire connected to the manufacturers antenna). We wouldn't send a kW through it, but thank you for the concern.  :)

I have been toying around with the idea (possibly for the next iteration) of a direct connection to a coaxial cable from the magnetron's resonant cavity. I need to research more about magnetrons which have a built in coax, but it seems like its possible, and might be an easier/cheaper conversion than an intermediate resonant cavity to send our signal into a vacuum chamber.

Anyone have any experience with magnetrons with built-in coaxial outputs?


Offline SeeShells

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I'm experiencing a complete disconnect from what you're doing here. Looking at the input side, which is a battery carried along for the ride - not external, please note - you state
Pin  = dm/dt c2

This says that the battery loses rest mass. That is true, but it is absolutely a tiny mass even over long periods of time, compared with the total rest mass of the device. How is this expected to "save overunity"?

Tell you what - prove it to yourself. Use the numbers I used before (1000 gee, 1 m radius, 100 m/s to my energy breakeven) and recalculate using your dm stuff. I guess you will not see any substantive difference.

My derivation of energy breakeven has been posted here several times. Tossing in some minuscule dm will not make any substantive difference. But you are welcome to go through it line by line and post your version.

If the battery and stored energy is on board the vehicle, that makes it easier. It will run out of fuel before it can go over unity.
Todd
Ahem. I thought we were discussing EmDrive, which is a propellantless vehicle. There is no exhaust. The onboard battery provides constant power Pin. The output power is pure kinetic. Ergo your calculation makes no sense when applied to the EmDrive.

The paradox with propellant driven space craft was explained too, by Dr. White. It occurs anytime "constant acceleration" is assumed, without taking into account the variables in the av(t) expression I posted. In the case of the EM drive where there is no exhaust, dm/dt is replaced by the change in potential energy from the small end, to the big end, per unit time, /c2.

And BTW, if the EM drive were to store every bit of energy put into it, with a high power source it would have to explode eventually. The energy either needs to escape, generate heat or move the thing in order to dissipate. Or else the source input will eventually become saturated until nothing more will go in.
Todd
When taking the time to explain on a reddit sub what a magnetron could put into a cavity the size of the frustum and what the effects would be to help them understand the problems the DYIers are facing using a high power device. I made the mistake of associating the cavity size with a bead box and putting a hair dryer into it. ... They sent me this link. http://what-if.xkcd.com/35/ Sorry Todd you just reminded me of it with your comment.

Offline TheTraveller

Further info on the antenna arrangement I'll be using on my 2.45GHz version of the Flight Thruster.

As the EM waves in a cavity with spherical end plates are spherical, the antenna also needs to be spherical as per the sidewall insertion point curve of the EM wave at that point.

I could have used a single stub 1/4 wave antenna curved to match the spherical EM wave shape but I had reservations that the end point of a single 1/4 wave stub inside the cavity may shift over time.

To stop any shifting, especially as I plan to ship finished EMDrives all over the planet, the single 1/4 wave stub antenna was replaced by 3 x 1/4 wave stub antennas that are joined at the centre and attached to the centre of 3 Rf connectors fitted into the side walls.

Trust the attached crude drawing makes it clear how I intend to excite TE013 mode and do so in a way to introduce min phase distortion into the internal resonant standing wave by the excitation antenna.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

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I'm experiencing a complete disconnect from what you're doing here. Looking at the input side, which is a battery carried along for the ride - not external, please note - you state
Pin  = dm/dt c2

This says that the battery loses rest mass. That is true, but it is absolutely a tiny mass even over long periods of time, compared with the total rest mass of the device. How is this expected to "save overunity"?

Tell you what - prove it to yourself. Use the numbers I used before (1000 gee, 1 m radius, 100 m/s to my energy breakeven) and recalculate using your dm stuff. I guess you will not see any substantive difference.

My derivation of energy breakeven has been posted here several times. Tossing in some minuscule dm will not make any substantive difference. But you are welcome to go through it line by line and post your version.

If the battery and stored energy is on board the vehicle, that makes it easier. It will run out of fuel before it can go over unity.
Todd
Ahem. I thought we were discussing EmDrive, which is a propellantless vehicle. There is no exhaust. The onboard battery provides constant power Pin. The output power is pure kinetic. Ergo your calculation makes no sense when applied to the EmDrive.

The paradox with propellant driven space craft was explained too, by Dr. White. It occurs anytime "constant acceleration" is assumed, without taking into account the variables in the av(t) expression I posted. In the case of the EM drive where there is no exhaust, dm/dt is replaced by the change in potential energy from the small end, to the big end, per unit time, /c2.

And BTW, if the EM drive were to store every bit of energy put into it, with a high power source it would have to explode eventually. The energy either needs to escape, generate heat or move the thing in order to dissipate. Or else the source input will eventually become saturated until nothing more will go in.
Todd
Each time I try to stay on topic with this breakeven business, which you say I have "wrong", you throw another spanner in the works. Let's try and focus here. I want to understand what's "wrong" as you see it. So far, you're not making sense to me. If you do want to make sense to me, and convince me that I'm "wrong", you're going to have to take my derivation and show, line by line, the "right" substitution.

Over to you.
« Last Edit: 07/09/2015 06:04 AM by deltaMass »

Offline ThinkerX

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I'm starting to think that Warp Tech and Delta Mass should establish a formal partnership.

Warp Tech proposes something.

Delta Mass points out a mathematical (or other flaw).

Warp Tech (usually) acknowledges flaw, and recalculates.

Delta Mass reviews again. 

And progress gets made.

Offline deltaMass

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It seems usually better with me to talk things out. It wasn't until I came on NSF that my thinking about propellantless propulsion in general crystallised into something really solid, despite having been thinking about it for many years, and bouncing ideas off other people. So thank you NSF folks for giving me the focus.

Offline OttO

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@Seeshells

Why not use an interferometer to measure the displacement? Too much noise?

http://www.instructables.com/id/Desktop-Michelson-Morely-Interferometer/
« Last Edit: 07/09/2015 07:00 AM by OttO »

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