Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797811 times)

Offline deltaMass

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Tossing Poynting vectors around begs the question of how sustained thrust at a level approximately Q times that of an equally-powered photon rocket could possibly obtain.

Online aero

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Ah, kdhilliard, i think i might have stolen the quote you typed out. However, this is speculation.

Quote
I'm pretty sure he is not saying that he has actually felt the thrust with his hand from any of his exiting drives, but instead that were you to build a model with higher thrust you could feel it

From the video you could take it either way. Either he has, or you would, feel a force. What is odd though is how do you get from a reaction-less drive that operates by bouncing microwaves around in a cavity, to something that behaves more like a traditional rocket. How do you make that leap. Perhaps Shawyer found the rocket like behaviour when he built his prototype, has mashed the two together because he is not quite sure what is going on, and has been hand-waving ever since.

Point of terminology - As Shawyer points out, this is not a reactionless drive, rather a propellant less drive.

Paraphrasing Newton's third law, Action = Reaction. Let's don't break that law along with all the others. If reaction = zero, then Action = zero and zero doesn't show on most force measuring devices that I know of.
« Last Edit: 05/24/2015 03:07 AM by aero »
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Offline Notsosureofit

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Added: As for the needed nonlinearity, it is the curving path of the radiation.

I think that's probably the result of a non-linearity.  But we have the differential heating of the end walls ?

Online aero

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Added: As for the needed nonlinearity, it is the curving path of the radiation.

I think that's probably the result of a non-linearity.  But we have the differential heating of the end walls ?

Yes, I was thinking about that, and the heating pattern is clearly the same as the claimed mode, per Dr. Rodal's calculation and images. But recall that the thrust is very low in the analyzed case, meaning that the RF was turning only a small amount. So is the heating pattern exactly the same, or are the hot spots moved toward the edge by a small amount?

The force on the big end would be something like
BigEndForce = SmallEndForce * (1 - cos(incident angle))
and if we assume a uniform rate of "turn" from the end of the dielectric to the big end, then the distance between the point of impact for a linear RF beam and a curving RF beam would be some integral of curve geometry that I don't have off the top of my head. This distance might or might not show on close examination of the thermal images and prediction theory. It's not likely to be obvious because ... well, just because.

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Offline Notsosureofit

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Added: As for the needed nonlinearity, it is the curving path of the radiation.

I think that's probably the result of a non-linearity.  But we have the differential heating of the end walls ?

Yes, I was thinking about that, and the heating pattern is clearly the same as the claimed mode, per Dr. Rodal's calculation and images. But recall that the thrust is very low in the analyzed case, meaning that the RF was turning only a small amount. So is the heating pattern exactly the same, or are the hot spots moved toward the edge by a small amount?

The force on the big end would be something like
BigEndForce = SmallEndForce * (1 - cos(incident angle))
and if we assume a uniform rate of "turn" from the end of the dielectric to the big end, then the distance between the point of impact for a linear RF beam and a curving RF beam would be some integral of curve geometry that I don't have off the top of my head. This distance might or might not show on close examination of the thermal images and prediction theory. It's not likely to be obvious because ... well, just because.

...because the beam image breaks down at wavelengths of the order of the cavity dimensions.  Makes the calculations a bear.  You have to think in terms of distortion of the wave functions instead (makes my head ache)

Offline Notsosureofit

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Tossing Poynting vectors around begs the question of how sustained thrust at a level approximately Q times that of an equally-powered photon rocket could possibly obtain.

You only have to prove it instantaneously.  Then it will hold in the frame of reference of the cavity due to GR.  Inertial frames won't do it, they aren't accelerating.

Online aero

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Now that you bring it up, I'm getting a head ache! And yes, the beam is supposed to be near cut-off, but at the small end, it's OK at the big end, isn't it? The cavity does resonate.

Continuing my simple minded geometric exercise for a curving beam - The dielectric messes up the simplicity of the calculations, but assuming that the RF radiation internal to the cavity imparts a plane wave force on the inside face of the dielectric, F = P*Q/c; Power, Quality factor over speed of light, then the thrust measured would be  - cos(incident angle))*P*Q/c so what was thrust in terms of P*Q/c ? I don't recall the details of the experiment for which the heating patterns were imaged.

And that doesn't seem right. I need to nail down just what angle I'm referring to and that means "stop posting on the fly and use a pencil and paper" until I can define my geometry, at least.
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Offline deltaMass

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« Last Edit: 05/24/2015 04:10 AM by deltaMass »

Offline WarpTech

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Tossing Poynting vectors around begs the question of how sustained thrust at a level approximately Q times that of an equally-powered photon rocket could possibly obtain.

It can't be sustained. It would violate CoE, which is where Shawyer seems to make an error IMO. There has to be a duty cycle involved, where for some length of time Q is charging and a shorter length of time (Much shorter) it is discharged. F = dp/dt  It could never "sustain" thrust (output power) at a level greater than the input power. It can be pulsed to get a particular delta-v however.




Offline WarpTech

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Tossing Poynting vectors around begs the question of how sustained thrust at a level approximately Q times that of an equally-powered photon rocket could possibly obtain.

You only have to prove it instantaneously.  Then it will hold in the frame of reference of the cavity due to GR.  Inertial frames won't do it, they aren't accelerating.

I doubt that. There is an accelerating reference frame of the photons relative to the frustum. There is no accelerating reference frame outside the frustum to propel it, and there is nothing "known" coupling the photons to the quantum vacuum. 

You can have a system whose NET momentum is 0, but the instantaneous momentum is not 0. For example, photons bouncing between two mirrors, the photons have an instantaneous momentum, but the NET of the system is 0.

Now, say there are a large number of photons bouncing between 2 mirrors. Considering only their momentum, if we introduce an asymmetry in attenuation and remove the input power at time t=0. Then, at some a later time t >> 0, the instantaneous momentum of the photons will be 0, but the NET momentum will depend on how many photons were absorbed in either direction. If the attenuation factor is skewed 80% in one direction over the other, then 80% of the photon's momentum will be absorbed in "that" direction. The instantaneous force will depend on how quickly they can be absorbed, dp/dt. It can never exceed the impulse of a photon rocket of output P*Q.

That's my theory, without the math. I need to show how the momentum is coupled from the field to the frustum asymmetrically, but I'm still learning about microwaves, design factors, components, etc... :)

Todd




Offline deltaMass

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Two errors there. First, momentum is conserved at all times in all sensible reference frames for a system comprising a photon bouncing between two mirrors. There is no "borrowing from The Cosmic Badger" going on. Secondly, please don't try and use "the reference frame of a photon", accelerated or otherwise. It's a semantic null statement to put things in that frame of reference. It's also another of Shawyer's conceptual errors.

Offline TheTraveller

To Iulian and other EM Drive replicators.

To test the linearity of your balance system use 2 coins of equal mass.

Put one coin on top of the centre of the frustum. Null the scale. Remove the coin and note weight reduction. Repeat 5 times and calc average.

Next put one coin on top of the centre of the frustum. Null the scale. Add one coin on top of the 1st and note weight increase. Repeat 5 times and calc average.

You now know how your balance system reports equal weight gain and loss. You can then use the measured factors to adjust the weight changes produced by your EM Drive in either orientation.
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Offline TheTraveller

The other way to put it - we can actually set up a situation where radiation pressure upon the big end is greater than that upon the little end. In space, put a flashlight inside the cavity, pointed upon the big end (which is not perfectly reflective). The radiation pressure upon the big end will be greater than that upon the small end, and the cavity will accelerate big end forward.

(The flashlight, if unsupported, will move in the opposite direction, like a photon rocket, but it could in principle be held in place, e.g. using magnetic levitation)

The flashlight is inside the cavity & will move to the small end, balancing the forces.
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Offline WarpTech

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http://arxiv.org/abs/0912.1031v1
Feigel says you can get thrust from the vacuum.

http://science.slashdot.org/story/09/12/11/149220/How-To-Build-a-Quantum-Propulsion-Machine
http://www.technologyreview.com/view/416614/a-blueprint-for-a-quantum-propulsion-machine/

This is not a theory, it's not even a well thought out hypothesis. First, he has to show what the ground state of these nanoparticles will be, as that is a state where they are in equilibrium with the QV. Then, he has to show there is a state of higher energy that can be pumped by the QV, and re-emitted to do real "work" for propulsion.  Right now, it's conjecture without a lot of explanation.

In a ferroelectric magnet there are domains where electrons have their spins aligned in a particular direction to create a stable magnetic field. The spin of the electron is in its quantum ground state, and spin is intrinsically an interaction between the electron and the QV. If the random spin-flips of electrons can be detected in either direction, then that is extracting energy from the QV.

Likewise, the electromagnetic ZPF is simply the 0 Temperature limit of Planck's blackbody temperature spectrum. If the temperature environment of the magnet is increased, the probability of spin-flips to a higher energy state becomes more likely. The symmetry is broken and can be detected as -dB/dt = curl(E). This can be used to extract electrical energy from the thermal input.

Todd



Offline TheTraveller

Finally completed a simple UI.

One thing to add is the ability to enter the small plate diameter - and switch between small plate diameter or design factor and have the other parameter computed and displayed.

Also a toggle for a small end cylinder. :)

Now to start messing with modes.

I prefer this better than a spreadsheet.  I wrote an Excel like spreadsheet years ago and even with the knowledge I have about them find them constricting.

The cutoff and guide wavelengths are different for TE and TM modes and what m,n values you use. This affects Df.

I adopted my spreadsheet to handle both TE01 and TM01 modes so a 1 cell binary change flips between them.

Length is then determined by numerically intergating 1,000 diameter changes between the end plates and working out the averaged guide wavelength to give 1/2 wave resonance. Then the driving Rf can be a harmonic of the averaged guide wavelength. Length is then adjusted so the external Rf harmonic is the same as the selected Rf wavelength.
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Offline TheTraveller

Two errors there. First, momentum is conserved at all times in all sensible reference frames for a system comprising a photon bouncing between two mirrors. There is no "borrowing from The Cosmic Badger" going on. Secondly, please don't try and use "the reference frame of a photon", accelerated or otherwise. It's a semantic null statement to put things in that frame of reference. It's also another of Shawyer's conceptual errors.

Just to be clear about errors.

Do you believe that Shawyer and the Chinese have made errors in measured thrust in their test devices and there is really no thrust?
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Offline zen-in

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...

In a ferroelectric magnet there are domains where electrons have their spins aligned in a particular direction to create a stable magnetic field. The spin of the electron is in its quantum ground state, and spin is intrinsically an interaction between the electron and the QV. If the random spin-flips of electrons can be detected in either direction, then that is extracting energy from the QV.

Likewise, the electromagnetic ZPF is simply the 0 Temperature limit of Planck's blackbody temperature spectrum. If the temperature environment of the magnet is increased, the probability of spin-flips to a higher energy state becomes more likely. The symmetry is broken and can be detected as -dB/dt = curl(E). This can be used to extract electrical energy from the thermal input.

Todd

That's a very good equivalence.   Momentum can't be removed from an isolated magnetic field that is at it's lowest energy level and momentum can't be removed from the QV.  It's the same analogy stated a while ago of the bank that floats your account by $100 and won't allow you to draw on that $100.  If any of that was true the universe would be very different and we would probably not be here.

http://math.ucr.edu/home/baez/vacuum.html

Offline WarpTech

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Two errors there. First, momentum is conserved at all times in all sensible reference frames for a system comprising a photon bouncing between two mirrors. There is no "borrowing from The Cosmic Badger" going on. Secondly, please don't try and use "the reference frame of a photon", accelerated or otherwise. It's a semantic null statement to put things in that frame of reference. It's also another of Shawyer's conceptual errors.

Okay, my example of mirrors is a bad one. Attenuation is a Lorentz force acting in the frustum that is asymmetrical. It has a unity power factor, and does more work in one direction than it does in the other direction.  Such that given N photons of momentum p0, the work they do as a percentage of thrust left, thrust right or generate heat, is not divided equally.

I did not imply an absolute reference frame, I said "relative". Relative to the frustum, the photons have wavelength A and the small end and wavelength B and the big end. This is by definition an accelerated reference frame between the field and the frustum. The only way to know it's accelerating is by the relative value of the wavelengths.





Offline deltaMass

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Two errors there. First, momentum is conserved at all times in all sensible reference frames for a system comprising a photon bouncing between two mirrors. There is no "borrowing from The Cosmic Badger" going on. Secondly, please don't try and use "the reference frame of a photon", accelerated or otherwise. It's a semantic null statement to put things in that frame of reference. It's also another of Shawyer's conceptual errors.

Just to be clear about errors.

Do you believe that Shawyer and the Chinese have made errors in measured thrust in their test devices and there is really no thrust?
I can understand your curiosity about what all the other pollsters believe, when you yourself are the sole occupant of one of the offered categories.

Offline RotoSequence

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I can understand your curiosity about what all the other pollsters believe, when you yourself are the sole occupant of one of the offered categories.

I think we should avoid getting personal and stick to the science. It seems that we've been drifting off track as of late. There are only a handful of completely honest and truthful statements we can make about EM drive at this time, and most of them involve explaining how and why the existing body of work is not friendly to thrust giving results. Not to discredit hard work and theory development, either by the great scientists who laid the foundations of modern physics, or the participants of the EM drive debate on either side of the fence, but failure to explain the thrust-positive results with analysis is not the same thing as nullifying the experiment's signal. Mathematical models and theories must play a secondary role to the apparatuses.
« Last Edit: 05/24/2015 08:38 AM by RotoSequence »

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