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#620 by oliverio on 23 Dec, 2015 03:24
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The issue with risk-aversion in labs is one that can only be properly understood, in my opinion, with either a little bit of game-theoretic economics-- or a lot of really strong intuition.
Essentially, it works like this: for any given profession with a risk of failure and a reward to innovation (where there is a higher opportunity cost for more ambitious innovation [that is to say, you could work on an emdrive for a year and possibly fail totally, or try to pursue some guaranteed scientific advancement that definitely helps society instead]), the center equilibrium will be driven away from maximally innovative and toward "innovative on the safe side."
The reason is obvious. You are a competitor for resources/fame/grant money/etc. If you attempt a very ambitious project, the rewards are maximal, but the penalty is also maximal for failure. If you attempt a very mundane project, there will be very little interest in your projects in terms of fame/grant money/etc.
So, the best bet will always be to attempt projects that are just a bit more ambitious than your peers-- because you will always look a bit more daring [which makes you stand out], and your failure will only be a bit larger than theirs [which doesn't stand out much]. HOWEVER-- this incentive to "marginally" one-up your peers is the glacier pushing science forward over time, you just can't expect very bold innovation.
There is only one obvious historic truth: very bold innovation comes from very bold innovators, not from science. Science is a tool we use to understand the world and make definite, slow, deliberate advancements. You cannot, however, poke scientists into vision. (Note that I mean nothing specific about anyone here or even the emdrive in particular.)
This is a well-understood phenomena that appears throughout any risk-reward betting schema where competition is involved in the model.
See: game-theoretic approaches to professional athlete decisionmaking, to peer-reviewed-science, first-mover advantage regarding industry innovation, et cetera. Any search of these terms on an academic index will be replete with game-theoretic evidence to the note of the following: until the emdrive is proven, universities are not likely to touch it. You look like too much of a fool if it turns out to be artifacts of measurement, and you will always just be the guy "replicating an obscure experiment" if you register thrust. -
#621 by ThereIWas3 on 23 Dec, 2015 03:26
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A trip through the Ex field after the magnetron has just shut off, going from the large end to the small end.
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#622 by SeeShells on 23 Dec, 2015 03:34
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Good grief no offense at all SteveD, I just drew a pic to make sure it was understood.Shell. Just saw your post on reddit. It strikes me that, while I'm not sure anyone is clear on the direction of movement in all these experiments, we seem to have a pattern emerging. Both plates solid, movement toward small end. Dielectric in small end, movement toward big end. Tuning screw in small end -- nothing. Tuning device in small end -- movement towards big end. Ends secured with loose clips -- nothing.
To answer your question in as few words to eliminate error. This is what was seen.
My working theory has been that very small forces are pernicious and end up working the tuning screw / clips off instead of driving the device forward. Seeing the direction of thrust reverse, similar to what seems to be reported for using a dielectric, makes me wonder about that. (Is your inside small base electrically conductive to the rest of the frustum? I know you have some form of seal on the inside so the thing isn't floating, but can this pass a current?)
Whatever the reason, I think you may have nulled the main force. Instead, you are seeing an opposite or retarding force against the large baseplate. Given the dimensions of the frustum (big base approximately equals length)this might be 1/4 of the force on the small base. Then again that NASA model somebody posted the other day showed much stronger fields on the small base than on the large one.
What I think this is showing is that the rf forces in the frustum are balanced. There's however a second force that is reacting to those rf forces on some kind of EM field strength per cm^2 of area basis. Fields are weaker at the large end, so more of that force is being produced at the small end. Null the smal; end and it moves towards the bigger end, though with less force. (Which makes me wonder how strong a none null main force would be).
At least that's where the observed data seems to be taking me.
Shell
Added: the reason it is with the micrometer big up point up is it's easier to get to turn instead of up and down from the floor, getting older you know.
One more thing, yes it's all electrically connected endplates to sidewalls.
I'm sorry if I somehow gave offense. So it seems that 1. much confusion reigns as to what direction the force is toward and 2. you measured force in the same direction as both NASA (presumably) at rfmwguy. Looks like the original reddit post got deleted. I do see why you would expect thrust in the other direction.
Might as well address some criticism I got for the original post. Let's say we had F = X in one direction and F = X/4 in the other direction. That actually makes some form of sense as this is, of course, a closed cavity in which we should expect F = X in both directions. Having F=0 in one direction would be unexpected (but then again so is X<1). If breaking electrical contact between one of the plates killed the force in that direction, then that would be relatively easy to test for. It would help explain the higher force on a curved large endplate (greater total area). It would also mean that we can stop trying to figure this out in terms of radiation pressure. Nicely this is also something testable and falsifiable (though perhaps not in Shells build). Put a removable insulator between the frustum and the baseplate (probably with a solid state build) and you can, relatively, quickly rule this in or out. Yes, I'm excited -- because some data is suggesting an experiment that would give us a better understanding of what's going on here.
One other thing is the copper walls seemed cool but the ceramic endplates felt a little warm. I guess they worked like they were suppose to. I didn't do any thermal on it as I was more concerned with the arcing I'd heard and to find out where it was and started the tear down to find it.
On for a bit. The issues with letting a "plate float" without connecting it to the frustum is it will arc. CSU Zachar, Woodward & Wanser had this very same issue of a plate floating and arcing.
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#623 by mwvp on 23 Dec, 2015 04:34
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see: http://emdrive.wiki/@notsosureofit_Hypothesis
That by itself still requires that the entropy of the enclosed system increases with acceleration. At this point I have convinced myself that that is so.
I've looked at your hypothesis a few times and have trouble understanding it. I'm an EE, not a physicist. I don't believe the system (frustrum-magnetron-battery-et.) is (en)closed, but is open in that heat is radiated, and the heat that is radiated is, indirectly, the exhaust momentum of the "rocket". And it would be indeed a rocket, if the frustrum is asymmetrically absorbing, rather than reflecting, EM momentum and converting it to radiant (or conducted) heat.
The frustrum as it accelerates and red-shifts microwave energy into the larger frustrum bottom mode (assuming, say a TE013 cavity) where greater losses result in greater heat dissipation, would indeed be increasing in entropy, for just that reason.In a cylindrical cavity the entropy of the wavefunction is maximized at free fall. The effect of acceleration is to induce a gravitational dispersion and lower the entropy. In a tapered (dispersive) cavity the effect of acceleration in a direction which reduces the dispersion, increases the entropy of the enclosed wavefunction. The classical case (photon gas) is valid for wavelengths which are much shorter than the cavity dimension (ie very high number mode structures). You can see this behavior in the chart as frequency increases.
I see a big difference in the effects of a gravitational acceleration field, and the physical acceleration of the frustrum on the microwave energy spectrum.
Is, over a short span of several meters, a gravitational field like earths significantly dispersive? Around a compact object like a black hole or neutron star, the acceleration gradient (tidal forces?) is significant.
Gravitation permeates the space inside the frustrum itself. And what it does to the forward wave it un-does on reflection, when energy reverses direction.
If the frustrum accelerates, the space inside, and propagating energy, is not affected. But the oblique reflection off the ends, and the tapered sidewalls, do result in phase shifting of the incident energy- doppler spreading.[ I spent way too much time trying to use the photon gas model when I should have remembered that Van Allen and Caravillano wrote a paper on the spherical harmonic modes of the earth-ionosphere system in '62 (?). Esp. as I wrote the Fortran program to do those calculations for them ! ]
Cool. Yesterday, a downloaded a dozen papers and a stack of books, furtively searching for how to do Laplace transforms on tapered waveguides and factor in doppler spreading. I'm thinking I can make an equivalent circuit model of the frustrum and multiply the terminating inductor of the ladder network with a complex coefficient in spice. I've been out of school quite a while, and never needed Laplace before now. -
#624 by mwvp on 23 Dec, 2015 04:56
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But what effect will acceleration have on an asymmetric, dissipative and dispersive high-Q energized cavity near cutoff?
Classically (special relativity only) the only effect having photons bouncing around inside a box is an added apparent mass of E/c², where E is the stored energy (in the form of "bound" electromagnetic energy flying inside).
My argument isn't about the mass of the microwave energy, but its asymmetrically reflected and dissipated momentum - Power/C.Being dissipative and dispersive, near cutoff somewhere inside shall make no difference in this regard : when all those specifics have been summarized as resulting to a certain Q value, that will give a stored_bound E for a given power input (at given frequency) and this tiny bound E equivalent mass is the only thing that will make a loaded cavity differ from an unloaded cavity as seen from the outside (+ it's radiating away waste heat). Obviously this equivalent mass is just the same as that lost by the battery to pump up an unloaded cavity to loaded state, so in principle we are just transferring a tiny tiny mass from one place to another (which is of very limited interest in terms of propulsion) before letting it bleed away at less than photon rocket efficiency.
this tiny bound E equivalent mass is the only thing that will make a loaded cavity differ from an unloaded cavity
Oh, no no no, its not the only thing! Consider the momentum/radiation pressure! The big end is dissipating more energy than the smaller, resulting in asymmetric, unbalanced force. And if the frustrum accelerated, the energy spectrum is being Doppler spread, resulting in additional energy penetrating/propagating further into the large end and dissipated. The force on a reflector is 2*P/C. The force on an absorber is P/C. Red-shifted energy from the apex penetrates and is preferentially dissipated in the tail. Blue-shifted energy from the tail is more poorly dissipated at the apex.
Furthermore, considering the low-pass and high-pass characteristics of the frustrum, and sympathetic resonances (high-frequencies will prefer the mode at the apex, low frequencies in the tail mode, for say, TE013), results in a characteristic which, in a way, does resemble a rocket engine. Momentum flows, a photon gas frequency spreads lower and it is exhausted as heat.
Moreover, I see this as sort of like BAE's photon recycling rocket, that recycles photons. The frustrum recycles photons until they a doppler shifted down after their momentum is harvested to do work, after which they are dissipated as exhaust heat.
I went too far yesterday trivializing the EM Drive, calling it a conventional heat engine. I think it uses conventional physics, and is a new, extraordinary, marvelous device that will exhibit negative inertial resistance/ratcheting. If you accelerate it forward, it will want to go faster and in reverse, will exhibit greater 'inertia'; not inertial mass, but an opposing reaction force due to radiation pressure in the frustrum.
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#625 by SteveD on 23 Dec, 2015 05:12
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There are no controversial physics either in photon rockets (inlcuding Bae's) or ion engines.
Both momentum and energy are conserved in Bae's concept. It cannot be used as a perpetual motion device.
There are no mysteries of energy conservation with ion engines either. Momentum and energy are also conserved in ion engines, which have been successfully tested since the 1960's and are well understood by aerospace engineers (they have been taught at MIT's Department of Aeronautics and Astronautics since the 1950's).
Having more propellant than someone may have predicted left after accelerating does not constitute an energy conservation mystery any more than your car having more fuel left after accelerating than what you predicted. The problem is with the faulty assumptions employed in the prediction of propellant consumption (including orbital mechanics gravity assist maneuver calculations, that are very dependent on precise knowledge of actual motion and any resistance met in close by slingshot around gravitational bodies), and the problem is not with the ion engine going over unity. There is no such thing as ion engines or photon rockets going over unity.
Ok, then let's put numbers to this, you can show me that I'm clearly wrong not only will I concede you're right, I'll take a break from posting for the month of January. Actually considering the math I'm asking you to do, let's make that Washington's Birthday on February 16th.
Am I correct that the equation in question reads: KE = 1/2mv^2. Where KE is the total kinetic energy of the rocket, m is its mass and v is its velocity. If this is the wrong equation, I'll look at the correct one and get back to you with a new set of questions.
What is being claimed is, that since v is squared a point is reached, less than the speed of light where an increase in v is great enough that it increases KE by more joules than contained in joules of input power. While several posters have claimed this takes place at a certain number, I'll ask that you do out the math (or actually just post an excel formula) so that we can all check to make sure this is correct.
My contention, looking at that formula, is that it implies that mass must be lost at a certain rate. If KE = 1/2mv^2 then to keep things from going over unity m must decrease as v increases. It would seem that in any constant mass scheme, that generates more thrust than a photon rocket, the increase of KE will go over input power (subject to checking that this isn't all bad math). A photonic laser thruster is a constant mass scheme. It would seem that unless it sheds mass, or suffers a power fall off, it will --eventually-- violate the classical equation. Show why a photonic laser thruster that reuses its photons 400 times (number given by Bae in his research report) and with an input power of 1kw won't go over unity on KE increase this side of c. Assume that the source laser is power by solar panels. (Alternatively, show that I have misread the equation and why this objection applies to an EMDrive but not a photonic laser thruster. Remember, to put numbers to what you are saying).
It also seems to me that the equation in question, assuming I have the right equation, posits a certain amount of loss of mass to keep things balanced. Can you produce the equation for this so that we can all see that current ion engines (or kicking a mirror out the back of a photonic laser rocket) isn't likely to cause a violation.
Win with math and I'm gone for a month and a half. -
#626 by OnlyMe on 23 Dec, 2015 05:13
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I've looked at your hypothesis a few times and have trouble understanding it. I'm an EE, not a physicist. I don't believe the system (frustrum-magnetron-battery-et.) is (en)closed, but is open in that heat is radiated, and the heat that is radiated is, indirectly, the exhaust momentum of the "rocket". And it would be indeed a rocket, if the frustrum is asymmetrically absorbing, rather than reflecting, EM momentum and converting it to radiant (or conducted) heat.
.....
The conclusion above is insightful. A transfer of momentum between the EM radiation and frustum walls is something that must occur at the surface, yet as that initial transfer of momentum, is randomized in the kinetic exchange of the atoms of the frustum wall it would become more thermal. Any momentum transfered directly from the microwaves to the frustum, could both contribute to thrust and then be thermally radiated.
The trick here would be to pin down just how momentum would be transferred preferentially in the direction of any measured thrust.
But this winds up a different mechanism than it seems you propose.
If there is useable thrust being developed, it is not thermal even should the energy involved ultimately be distributed through out the frustum walls and radiated as thermal energy. IOW if heat is what the thrust is being generated by, the EMDrive returns to the classification of a curiosity.
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#627 by Emmett Brown on 23 Dec, 2015 06:18
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There are a lot of theoretical discussions considering radiation pressure and photon momentum.
While these effects are real, their forces are many orders of magnitude too small to be significant.
The radiation pressure of the sun, at the surface of the sun itself is only 0.22 N/m2
See
For more info on radiation pressure see @ 58:40
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#628 by mwvp on 23 Dec, 2015 07:54
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The conclusion above is insightful. A transfer of momentum between the EM radiation and frustum walls is something that must occur at the surface, yet as that initial transfer of momentum, is randomized in the kinetic exchange of the atoms of the frustum wall it would become more thermal. Any momentum transfered directly from the microwaves to the frustum, could both contribute to thrust and then be thermally radiated.
The transfer of momentum, from my EE perspective, is mediated by fields, I would think mostly magnetic. The flux from the oscillating modes in the enclosed space in the cavity induce currents in the frustrum, which oppose the changing fields, reflect the propagating momentum, and experience reaction force. The induced wall currents are also reduced by I^2 R losses, and cause heating.The trick here would be to pin down just how momentum would be transferred preferentially in the direction of any measured thrust.
If the frustrum top is 15 cm dia., the area is 225 cm^2. The bottom, 25 cm dia., 625 cm^2. 625/225 = 2.7
So one might naively assume the bottom losses are around three times what the top losses are, and since the radiation pressure on a reflector is twice that of an absorber, then one would expect about three times the momentum creating pressure in the forward direction. From dissipation alone, neglecting acceleration effects.
And I am aware the pressure depends on surface area of the reflector/absorber, but I the sidewalls can hardly be neglected.
A static Meep/MPD analysis could confirm or refute this.
More complicated is an analysis of the dynamics of an accelerating frustrum.But this winds up a different mechanism than it seems you propose.
How so?If there is useable thrust being developed, it is not thermal even should the energy involved ultimately be distributed through out the frustum walls and radiated as thermal energy. IOW if heat is what the thrust is being generated by, the EMDrive returns to the classification of a curiosity.
Agreed. The thrust generated will be on the order of cavity Q times the input power radiation pressure, many orders of magnitude greater than the mere thermal radiation pressure from the hot frustrum. It wouldn't even be worth bothering to focus the radiated infrared to get its extra miniscule thrust. -
#629 by mwvp on 23 Dec, 2015 08:01
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There are a lot of theoretical discussions considering radiation pressure and photon momentum.
While these effects are real, their forces are many orders of magnitude too small to be significant.
The radiation pressure of the sun, at the surface of the sun itself is only 0.22 N/m2
Ha! The radiation pressure is the cavity Q times the input power. The Q of the cavity could well be 10,000. Sapphire beads can increase cavity Q (with unknown dragging effects) to a million. Superconducting cavities can be in the billions for microwaves, and hundreds of billions for light.
What is needed is a method, such as what the EM drive may be doing and what Bae in fact does - recycle or trap photons while each tiny reaction impulse of work is extracted, red-shifting them down in energy. -
#630 by rfmwguy on 23 Dec, 2015 10:37
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Very impressive commentary...I'm starting to sense a workable theory. Its the first time I remember reading a description of why Q is so important. It is a multiplier of sorts, the ability to build up/reflect photonic energy to a breakpoint? Am I close?
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#631 by TheTraveller on 23 Dec, 2015 10:54
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Very impressive commentary...I'm starting to sense a workable theory. Its the first time I remember reading a description of why Q is so important. It is a multiplier of sorts, the ability to build up/reflect photonic energy to a breakpoint? Am I close?
Higher Q increases the stored energy in a resonant cavity. The E or P in the radiation pressure equation thus increases as the Q increases. You could write it as Radiation Pressure on an end plate of a resonant cavity = (2 P Qunloaded) / c. With P being applied Rf forward power. Of course as the EM wavelength is longer inside a waveguide you also need to multiply the F by (wavelength external / guide wavelength) to get the reduced Force generated from the longer guide wavelength..
As Q increases so too does cavity TC (Q unloaded / (2 Pi Freq) and cavity fill time being TC x 5. So it all locks together. -
#632 by frobnicat on 23 Dec, 2015 11:03
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There are no controversial physics either in photon rockets (inlcuding Bae's) or ion engines.
Both momentum and energy are conserved in Bae's concept. It cannot be used as a perpetual motion device.
There are no mysteries of energy conservation with ion engines either. Momentum and energy are also conserved in ion engines, which have been successfully tested since the 1960's and are well understood by aerospace engineers (they have been taught at MIT's Department of Aeronautics and Astronautics since the 1950's).
Having more propellant than someone may have predicted left after accelerating does not constitute an energy conservation mystery any more than your car having more fuel left after accelerating than what you predicted. The problem is with the faulty assumptions employed in the prediction of propellant consumption (including orbital mechanics gravity assist maneuver calculations, that are very dependent on precise knowledge of actual motion and any resistance met in close by slingshot around gravitational bodies), and the problem is not with the ion engine going over unity. There is no such thing as ion engines or photon rockets going over unity.
Ok, then let's put numbers to this, you can show me that I'm clearly wrong not only will I concede you're right, I'll take a break from posting for the month of January. Actually considering the math I'm asking you to do, let's make that Washington's Birthday on February 16th.
Maybe I can try again to explain that (dr Rodal has far more valuable insights than me on some more advanced tools than needed for just that) though if you are not convinced already by the equations and arguments already given I fear this is a never ending endeavor to get that through...
First, this is not a decisive scientific argument in itself but has some weigh, as the body of knowledge of science arises from a consensus (among very nitpicking people) of what is valid or not to explain what is observed and "operational" in nature (including artificial devices and formal systems such as maths). From a sociological point of view, do you really think that if classical action/reaction schemes (chemical rockets, ion thrusters, photon rockets) were in tension with the conservation theorems (CoEnergy, CoMomentum) of classical frameworks that wouldn't be big news (since Goddard !) and there would be thousands of essays to reconcile the frameworks with such issue ? Such tension would have gone unnoticed or ignored by so many smart and nitpicking people ? On the relatively obscure and unattractive (to the wider community) subject of SPPPDSBT3 self powered propellantless propulsion in deep space at better than 3.33µN/kW (not solar sailing, not electrodynamic tethers, not photon rockets) of which we know a few "concepts" (Emdrive, Woodward effect, Dean drive) there are always different people arriving raising the solid argument based on classical framework that there (on such SPPPDSBT3 concepts) appear to be a straightforward issue with conservation, not only conservation of momentum but also of energy (as both are linked). I'm too tired of googling around to do that now, but if really needed to convince of that I could easily find dozens online writings spanning the last 20 years showing how dozens of different persons (that couldn't possibly all belong to that same antiSPPPDSBT3 kabbalah unless you are irremediably into delusional and pathological paranoid conspiracy thinking) just, you know, just right away think "hey, there is an issue with CoE here !", and more often than not before even being aware such remark was done before by others. An interesting test would be to present the SPPPDSBT3 concept phenomenologically (assume we have a device that does thrust etc...) to a significant sample of physics professor,and see how many of them come to the same conclusion.
Happen to be, the only place where people think that there might be some issues of conservation with conventional propulsion schemes is in forums talking SPPPDSBT3, and in a few writings of Woodward or cosigned White, both proponents of SPPPDSBT3, as a counter argument that while SPPPDSBT3 does look like it has some issue with conservation of energy (this tells enough as how hard it is to argue against that), so do the conventional schemes.
This is not a decisive core scientific argument per se, but think about that.
I don't have time right now but bookmark your post as to follow up with the core argument, hopefully in the terms you ask questions, though this is not the easiest. I have done already in a more straightforward setting which is constant velocity constant thrust and no kinetic energy involved. Please read again carefully how in such setting (a "tractor" using power to push at constant force and constant velocity, not to gain velocity) the SPPPDSBT3 has an issue with CoE that other conventional schemes don't have. Do you agree with that, and if not where exactly Only power(W), force(N), relative velocities(m/s), mass flow rates (kg/s) involved.
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#633 by Notsosureofit on 23 Dec, 2015 11:13
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@Rodal
Working, so have to run back and forth....
So, 1/D^2 {as fn of x} = (1/Ds^2) - (x/L)((1/Ds^2)-(1/Db^2)) for x from 0 to L, to give linear dispersion (in this simple model) so as to be completely eliminated by the "gravitational" dispersion at some acceleration.
Make sense ?
So in the final analysis, is the optimal shape a simple cone (linear with x?)
No, for linear dispersion D {as fn of x} = ( (1/Ds^2) - (x/L)((1/Ds^2)-(1/Db^2)) )^(-0.5)
Right ? (hard when brain gets this old)
##$^&& .. still can't send a picture !!
Does (1/2 of) the optimal cross-sectional shape (parallel to the axis of axisymmetry) for the NososureofitEMDrive look like this picture ?
(see attachment)
So looks a lot like rfmwguys compressed mesh cavity shape.....
(this is, of course, still a simplified model based on cylindrical cavity calculations) -
#634 by Rodal on 23 Dec, 2015 12:06
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Nowhere in Shawyer's or Yang's formulations do they postulate a change in mass. On the contrary, they postulate that the EM Drive is a closed system with no mass or energy going in or out of it.
There are no controversial physics either in photon rockets (inlcuding Bae's) or ion engines.
Both momentum and energy are conserved in Bae's concept. It cannot be used as a perpetual motion device.
There are no mysteries of energy conservation with ion engines either. Momentum and energy are also conserved in ion engines, which have been successfully tested since the 1960's and are well understood by aerospace engineers (they have been taught at MIT's Department of Aeronautics and Astronautics since the 1950's).
Having more propellant than someone may have predicted left after accelerating does not constitute an energy conservation mystery any more than your car having more fuel left after accelerating than what you predicted. The problem is with the faulty assumptions employed in the prediction of propellant consumption (including orbital mechanics gravity assist maneuver calculations, that are very dependent on precise knowledge of actual motion and any resistance met in close by slingshot around gravitational bodies), and the problem is not with the ion engine going over unity. There is no such thing as ion engines or photon rockets going over unity.
Ok, then let's put numbers to this, you can show me that I'm clearly wrong not only will I concede you're right, I'll take a break from posting for the month of January. Actually considering the math I'm asking you to do, let's make that Washington's Birthday on February 16th.
Am I correct that the equation in question reads: KE = 1/2mv^2. Where KE is the total kinetic energy of the rocket, m is its mass and v is its velocity. If this is the wrong equation, I'll look at the correct one and get back to you with a new set of questions.
What is being claimed is, that since v is squared a point is reached, less than the speed of light where an increase in v is great enough that it increases KE by more joules than contained in joules of input power. While several posters have claimed this takes place at a certain number, I'll ask that you do out the math (or actually just post an excel formula) so that we can all check to make sure this is correct.
My contention, looking at that formula, is that it implies that mass must be lost at a certain rate. If KE = 1/2mv^2 then to keep things from going over unity m must decrease as v increases. It would seem that in any constant mass scheme, that generates more thrust than a photon rocket, the increase of KE will go over input power (subject to checking that this isn't all bad math). A photonic laser thruster is a constant mass scheme. It would seem that unless it sheds mass, or suffers a power fall off, it will --eventually-- violate the classical equation. Show why a photonic laser thruster that reuses its photons 400 times (number given by Bae in his research report) and with an input power of 1kw won't go over unity on KE increase this side of c. Assume that the source laser is power by solar panels. (Alternatively, show that I have misread the equation and why this objection applies to an EMDrive but not a photonic laser thruster. Remember, to put numbers to what you are saying).
It also seems to me that the equation in question, assuming I have the right equation, posits a certain amount of loss of mass to keep things balanced. Can you produce the equation for this so that we can all see that current ion engines (or kicking a mirror out the back of a photonic laser rocket) isn't likely to cause a violation.
Win with math and I'm gone for a month and a half.
So, as soon as you propose that the EM Drive losses mass you are departing from the EM Drive cannon of Shawyer and Yang. If you propose this you have to address how is the mass being lost. What's more outstanding is that they propose to address the issue of conservation of momentum and conservation of energy solely by using Maxwell's equations (and also Special Relativity in the case of Shawyer), which is clearly a non-starter. Dr. White recognizes this huge blunder by Shawyer and Yang, and that's why he proposes a mutable Quantum Vacuum to get out of the non-viable proposal that a closed system can experience self-acceleration just by using Maxwell's equations (Shawyer's proposal is non-viable because it is well-known that Maxwell's equations satisfy conservation of momentum). (*)
If you postulate losing mass as a conventional rocket (a chemical rocket or an ion rocket for example) then there is nothing unconventional about the EM Drive except for being one of the most inefficient worst kinds of rockets in existence. This is indeed quite possible but it would really shatter the dreams of the "EM Drive believers" as it simple to then show that such an EM Drive cannot compete with other rocket drives.
If you apply General Relativity, mass and energy are equivalent and hence you are equivalently postulating losing energy.
Another proposal would be to address the increase in mass that occurs with increasing speed according to the theory of Relativity. This proposal to address this conundrum , has already been mathematically addressed by WarpTech who exhaustively looked at this problem against the skeptical views of DeltaMass and Frobnicat in previous threads. Rather than repeat the whole argument and counter-argument please look at user Warp-Tech's previous posts in this regards and the answers to his posts. Of course, one problem is that the relativistic change in mass is negligible unless the spacecraft achieves a speed close to the speed of light.
Suffice it to say that WarpTech soon arrives at the conclusion that it is not possible to consistently state that constant power will mean constant acceleration for the EM Drive, as proposed by EM Drive "believers".
All these arguments were previously discussed mathematically.
This was posted by WarpTech before rfmwguy was moderating these threads and a number of new posters started to post these same old arguments that have been previously addressed.
If you want to re-open these discussions, because you have a mathematical proposal that has not been previously discussed, you will need to show your new equations.
________________
(*) The mutable, degradable QV proposed by Dr. White has been addressed separately.
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#635 by rfmwguy on 23 Dec, 2015 13:01
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@Rodal
Working, so have to run back and forth....
So, 1/D^2 {as fn of x} = (1/Ds^2) - (x/L)((1/Ds^2)-(1/Db^2)) for x from 0 to L, to give linear dispersion (in this simple model) so as to be completely eliminated by the "gravitational" dispersion at some acceleration.
Make sense ?
So in the final analysis, is the optimal shape a simple cone (linear with x?)
No, for linear dispersion D {as fn of x} = ( (1/Ds^2) - (x/L)((1/Ds^2)-(1/Db^2)) )^(-0.5)
Right ? (hard when brain gets this old)
##$^&& .. still can't send a picture !!
Does (1/2 of) the optimal cross-sectional shape (parallel to the axis of axisymmetry) for the NososureofitEMDrive look like this picture ?
(see attachment)
So looks a lot like rfmwguys compressed mesh cavity shape.....
(this is, of course, still a simplified model based on cylindrical cavity calculations)
Yes, this shape is almost identical to the rough tuning I did with the brass rings against the mesh. I might consider this down the road after the 1st run with the solid sidewalls. Can someone quantify what this proposed shape adds to either return loss or Q?
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=39004.0;attach=1089017
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#636 by rfmwguy on 23 Dec, 2015 13:15
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Because of the serial thread structure of NSF, I think we have to understand that it is difficult to extract previous formula/data/posts...especially across 6 threads and hundreds of pages. The forum here works well, but searching/cataloging across threads is not a strong suite, but it is what we have to work with.
(...)
It also seems to me that the equation in question, assuming I have the right equation, posits a certain amount of loss of mass to keep things balanced. Can you produce the equation for this so that we can all see that current ion engines (or kicking a mirror out the back of a photonic laser rocket) isn't likely to cause a violation.
Win with math and I'm gone for a month and a half.
All these arguments were previously discussed mathematically.
This was before rfmwguy was moderating these threads and a number of new posters started to post these same old arguments that have been previously addressed.
If you want to re-open these discussions, because you have a mathematical proposal that has not been previously discussed, you will need to show your new equations.
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(*) The mutable, degradable QV proposed by Dr. White has been addressed separately.
Perhaps it is best for those who know exactly where the data resides to please link to it in commentary. I believe this will help new readers and posters. New readers are arriving daily and few may even know where to find the old info.
I know Chris wants to provide a helpful, welcoming environment for all in this topic and I believe linking to previous, relevant posts is more aligned with the spirit of the overall forum. -
#637 by Rodal on 23 Dec, 2015 13:47
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Because of the serial thread structure of NSF, I think we have to understand that it is difficult to extract previous formula/data/posts...especially across 6 threads and hundreds of pages. The forum here works well, but searching/cataloging across threads is not a strong suite, but it is what we have to work with.
(...)
It also seems to me that the equation in question, assuming I have the right equation, posits a certain amount of loss of mass to keep things balanced. Can you produce the equation for this so that we can all see that current ion engines (or kicking a mirror out the back of a photonic laser rocket) isn't likely to cause a violation.
Win with math and I'm gone for a month and a half.
All these arguments were previously discussed mathematically.
This was before rfmwguy was moderating these threads and a number of new posters started to post these same old arguments that have been previously addressed.
If you want to re-open these discussions, because you have a mathematical proposal that has not been previously discussed, you will need to show your new equations.
________________
(*) The mutable, degradable QV proposed by Dr. White has been addressed separately.
Perhaps it is best for those who know exactly where the data resides to please link to it in commentary. I believe this will help new readers and posters. New readers are arriving daily and few may even know where to find the old info.
I know Chris wants to provide a helpful, welcoming environment for all in this topic and I believe linking to previous, relevant posts is more aligned with the spirit of the overall forum.
It is presumptive to assume that anybody (with memory of such content) is going to know exactly on what thread and what post number a given user's comment is going to be located. Of course memory of previous discussions does not entail memory of the exact time and post number at which the discussion took place.
Anybody with a modicum of interest can do that search on their own time. The time-consuming search process, entailing having to read old comments is itself helpful to such a person unfamiliar with the old thread's content to familiarize herself with such old comment. It is unreasonable to put that burden on the shoulders of the people that graciously enough take their valuable time to help narrow the search parameters by indicating how they can narrow that search (in this case for example by indicating that they can find it under the username: WarpTech, and that the posts are located in threads prior to the ones you moderated). -
#638 by Flyby on 23 Dec, 2015 13:58
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........
Not sure if my knowledge of English has captured all the required finesse, but it is a bit harsh to link the increase in new EM-drive speculations with the rfmwguy's moderation...
All these arguments were previously discussed mathematically.
This was before rfmwguy was moderating these threads and a number of new posters started to post these same old arguments that have been previously addressed.
If you want to re-open these discussions, because you have a mathematical proposal that has not been previously discussed, you will need to show your new equations.
......
I do not think there is any proven correlation between the 2...an unfortunate coincidence, maybe?
What you could ask from a moderator however, is to keep a more neutral ground in the discussions. rfmwguy clearly has an opinion on things that could, on the long run, compromise the expected neutrality of a moderator. But that is, in the first place, his task to moderate him selves.
But as I perceive it, I don't think he made any grave errors so far...
If you feel he's stepping a bit out of his role as moderator, it might just be enough to remind him of his function, no?
There should be room for both hardcore physics discussions as well for some more philosophical ideas, although admittedly, the latter are considerably harder to moderate due to their more emotional nature.
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#639 by rfmwguy on 23 Dec, 2015 14:03
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Happy Holidays to all on the emdrive threads!
