Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2163566 times)

Offline zen-in

  • Full Member
  • ****
  • Posts: 531
  • California
  • Liked: 468
  • Likes Given: 365

Nope. (and I dare say, we are yet to see the charts recording those "insignificant thrusts" with or without such or such dielectric thereof, but this is an aside)

My conjecture is not about dielectric disc's CoM shift playing an important role in the thrust (did I say that ? Where ?) My conjecture is about some test article part's CoM shifting to the left (toward the small end) relative to fixation on the arm. Now what is susceptible to move to the left ? You know that better than anyone, you "invented" the inward buckling of the big end cap. The part that is the most heavily heated (granted this is not by a blowtorch !) and that has a boundary constraint such that, in first approximation, there is a square root between the delta expansion in plane and the resulting displacement perpendicular to plane : buckling is a very efficient amplifier. Under such buckling or near buckling conditions, the mass*displacement of the big end cap would play the major part of test article CoM's shift. Quantitative estimates ongoing...

The problem with thermal explanations is that, in particular in vacuum, given the low temperature deltas (a few °C) the evacuated heat rates are quite low relative to the received powers. The time constants to thermal equilibrium appear way beyond the 45s of a whole run. Therefore the fact that on some "thrusts" rises we see what looks like a thermal first order constant rate heat charge against a proportional loss don't hold water. At 45s the various parts are still swallowing heat at constant rate and evacuating near to none, we would have a near linear rise in temperature wrt time all way through. So if LDS delta is proportional to Com shift (as per the tilted pendulum component), Com shift proportional to expansion, expansion proportional to temperature, and temperature proportional to time, we should see a linear rise, and not a "step". Yes but the buckling could make Com shift proportional to square root of expansion. Now look at the chart below and see the step not as a cst-cst*exp(-cst*t) as per a naive thermal explanation but as a cst*sqrt(cst*t).

So the "attack" and the "sustain" can both be very well explained by progressive thermal expansion near buckling conditions and by a slightly tilted Z axis. Now for the fall (decay) : for those still believing that thermal explanations are irrelevant, how is it possible that the decay is lingering at high LDS values for so long after power off ? But, with so low thermal radiation for cooling, there is no reason (from my conjectures so far) that there would be any significant decay at all : from my hypothesis the signal should stay constantly high at power off, only starting falling at a very small rate (much smaller that the rise rate).

This is why I said in previous post to Star-Drive that I don't believe in thermal effect as being the only cause of observed signal, from the shapes. Not because of rise and sustain (square root buckling amplification + tilted Z allowing for sustained "thrusts" by sustained relative Com's displacements) but because of decay. I do have an idea to explain that : Rodal have you considered that the supporting copper ring around the FR4 big end cap would also expand thermally ? What would happen if there was a (thermal conduction driven) temperature "delay" between the cap and the ring so that when the power stops the difference between cap temperature and ring temperature falls fast enough to be compatible with the time constant of the observed decay ? This is my leading conjecture. I now do believe again in the possibility of a purely thermal explanation wholly consistent with both magnitude and shape of signal.


It's amazing how long this discussion has gone on.   All the brilliant individuals who have contributed complex physical and mathematical methods of analyzing this device; yet there is still not an accepted explanation for the anomalous thrust.   

There are several observations that can't be disputed:

1)  The thrust signature for both the Cannae device and the Eagleworks cone shaped cavity are similar to the thrust signature of the capacitor calibrator.   All are underdamped and have nearly the same natural frequency.    This is to be expected because all are step responses.   However this is only true for thrust waveforms from the AIAA Aug 2014 paper.

2)  The correction for error thrust due to PA current interacting with the damping magnets is not done for the vacuum tests.   It appears this error source was eliminated.

3)  The thrust signature for the vacuum tests are very different.   There is no overshoot or ringing, the rise time is slow, and a residual thrust remains after the RF is turned off.    This test, if it was to confirm earlier results, would have to have the same thrust signature (overdamped).   Instead it looks like a thermal effect.   The displacement is very small (from 1 - 4 micrometers).

One possible explanation is that the PA current went up when the dielectric material was put in the cavity, due to a higher SWR.   If the PA current was above the level that was used to measure the correction factor then the anomalous thrust seen was just more magnetic torque.   Since this correction was not used with the vacuum tests it can be assumed the problem was mitigated - maybe by coaxializing the power leads.   Frobnicat has proposed an explanation for the residual force seen in the vacuum measurements.   With no air surrounding the cavity it takes much longer for the heat to escape.   Some kind of long duration thermal flexing is causing a change in the LDS reading.   It may be because the alignment of the beam changes ever so slightly when the CM changes.   

The indisputable fact that the two sets of experiments show a thrust waveform with very different shape even though the TP has not been changed invalidates the claims.

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6045
  • Likes Given: 5325

....


It's amazing how long this discussion has gone on.  ....yet there is still not an accepted explanation for the anomalous thrust...   There are several observations that can't be disputed:

....
Given 1) the extremely small funding (by any objective assessment) of the NASA Eagleworks project,  2) the small magnitude of the measurements involved, 3) the outstanding claims (including issues of conservation of momentum), and 4) the barely 6 months since the release of the "Anomalous..." report and the discussion in this thread, I don't find it at all "amazing" that there is no uniformly accepted mechanism for the measurements.  Actually I don't understand what "acceptance" could possibly mean in this context (an anonymous Internet forum thread).

So, an objective definition of "acceptance" must mean scientific community acceptance.  As far as acceptance in the scientific community at large, such "acceptance" could only be expected after attempts have been made to reproduce the results at academic institutions, and for that to happen (given the small level of funding for this project) it would take much more than 6 months (certainly a Ph.D. thesis at a major university would take years).  We are not even at the point where there is certainty that NASA Glenn will try to replicate the tests (and much less at the point of replicating the tests at leading universities)

A fair assessment acknowledges that progress has been made in eliminating proposed explanations for the thrust measurement being an experimental artifact.  For example:

Observation #1) The explanation (e.g. the jet model from a poster in this thread, and alternative air current conjectures in several blogs in the Internet) that the thrust measurements were due to thermal convection in the air has been nullified by NASA Eagleworks tests in a vacuum at  6.6*10^(-9) standard atmosphere = 0.0000000066 standard atmosphere

...


Karl Popper: The Logic of Scientific Discovery (1934).

There is always some uncertainty associated with scientific conclusions; physical sciences never absolutely prove anything (unlike Mathematics).  What physical sciences do is nullify false explanations.



John von Neumann

Quote
The sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena.
"Method in the Physical Sciences", in The Unity of Knowledge (1955), ed. L. G. Leary (Doubleday & Co., New York), p. 157
« Last Edit: 03/13/2015 01:53 PM by Rodal »

Offline zen-in

  • Full Member
  • ****
  • Posts: 531
  • California
  • Liked: 468
  • Likes Given: 365

....


It's amazing how long this discussion has gone on.  ....
There are several observations that can't be disputed:


There are several observations that can't be disputed:

1)  The thrust signature for both the Cannae device and the Eagleworks cone shaped cavity are similar to the thrust signature of the capacitor calibrator.   All are underdamped and have nearly the same natural frequency.    This is to be expected because all are step responses.   However this is only true for thrust waveforms from the AIAA Aug 2014 paper.

2)  The correction for error thrust due to PA current interacting with the damping magnets is not done for the vacuum tests.   It appears this error source was eliminated.

3)  The thrust signature for the vacuum tests are very different.   There is no overshoot or ringing, the rise time is slow, and a residual thrust remains after the RF is turned off.    This test, if it was to confirm earlier results, would have to have the same thrust signature (overdamped).   Instead it looks like a thermal effect.   The displacement is very small (from 1 - 4 micrometers).

One possible explanation is that the PA current went up when the dielectric material was put in the cavity, due to a higher SWR.   If the PA current was above the level that was used to measure the correction factor then the anomalous thrust seen was just more magnetic torque.   Since this correction was not used with the vacuum tests it can be assumed the problem was mitigated - maybe by coaxializing the power leads.   Frobnicat has proposed an explanation for the residual force seen in the vacuum measurements.   With no air surrounding the cavity it takes much longer for the heat to escape.   Some kind of long duration thermal flexing is causing a change in the LDS reading.   It may be because the alignment of the beam changes ever so slightly when the CM changes.   

The indisputable fact that the two sets of experiments show a thrust waveform with very different shape even though the TP has not been changed invalidates the claims.
Actually, an objective, fair assessment starts by acknowledging that progress has been made in eliminating proposed explanations for the thrust measurement being an experimental artifact.  For example:

Observation #1) The explanation (e.g. @frobnicat's jet model, and by several blogs in the Internet) that the thrust measurements were due to thermal convection in the air has been nullified by NASA Eagleworks tests in a hard vacuum at  6.6*10^(-9) standard atmosphere = 0.0000000066 standard atmosphere


While the vacuum test did invalidate the theory of anomalous thrust being the result of air currents it also invalidated the anomalous thrust.   The earlier STP tests and the vacuum test were done with the same hardware and had the same driving function.    The system response should be similar but they aren't.  There are two different causes for the indication of an anomalous thrust.   Therefore there is no thrust.
« Last Edit: 03/13/2015 07:22 PM by zen-in »

Online RotoSequence

  • Full Member
  • ****
  • Posts: 775
  • Liked: 570
  • Likes Given: 780
While the vacuum test did invalidate the theory of anomalous thrust being the result of air currents it also invalidated the anomalous thrust.   The earlier STP tests and the vacuum test were done with the same hardware and had the same driving function.    The system response should be similar but they aren't.  There are two different causes for the indication of an anomalous thrust.   Therefore there is no anomalous thrust.

The behavior of the hardware is inconsistent in different atmospheric conditions, but there is a consistent, small measurement that shows up after the power is turned off, therefore it must be thermal, ergo there is nothing happening?  :o

That sounds like a mighty big leap, to me.
« Last Edit: 03/13/2015 02:47 PM by RotoSequence »

Offline Superfastjellyfish

  • Member
  • Posts: 7
  • Plastic Beach
  • Liked: 5
  • Likes Given: 393

....


It's amazing how long this discussion has gone on.  ....
There are several observations that can't be disputed:

....
Actually, an objective, fair assessment starts by acknowledging that progress has been made in eliminating proposed explanations for the thrust measurement being an experimental artifact.  For example:

Observation #1) The explanation (e.g. @frobnicat's jet model, and by several blogs in the Internet) that the thrust measurements were due to thermal convection in the air has been nullified by NASA Eagleworks tests in a hard vacuum at  6.6*10^(-9) standard atmosphere = 0.0000000066 standard atmosphere

...


Karl Popper: The Logic of Scientific Discovery (1934).

There is always some uncertainty associated with scientific conclusions; physical sciences never absolutely prove anything (unlike Mathematics).  What physical sciences do is nullify false explanations.



John von Neumann

Quote
The sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena.
"Method in the Physical Sciences", in The Unity of Knowledge (1955), ed. L. G. Leary (Doubleday & Co., New York), p. 157

While the vacuum test did invalidate the theory of anomalous thrust being the result of air currents it also invalidated the anomalous thrust.   The earlier STP tests and the vacuum test were done with the same hardware and had the same driving function.    The system response should be similar but they aren't.  There are two different causes for the indication of an anomalous thrust.   Therefore there is no anomalous thrust.

I'm probably misunderstanding you, but in the following post, Paul March says:

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329225#msg1329225
"As to why the vacuum test were observing less thrust than in air tests. please note the difference in the RF amps there were driving each test series.  The 30W Mini-Circuit Class-A RF amp was used for the in-air series reported in the 2014 JPC paper, whereas a 100W EMPower Class-A/B RF amplifier was used in the vacuum tests to date. "

Offline JPLeRouzic

  • Member
  • Posts: 27
  • France, Rennes
  • Liked: 9
  • Likes Given: 29
Observation #1) The explanation (e.g. the jet model from a poster in this thread, and alternative air current conjectures in several blogs in the Internet) that the thrust measurements were due to thermal convection in the air has been nullified by NASA Eagleworks tests in a vacuum at  6.6*10^(-9) standard atmosphere = 0.0000000066 standard atmosphere
If some kind of perfect Ion engine expels a gas with a density as thin as the one in the NASA Eagleworks vacuum chamber, through a one cm3 nozzle and at a relativistic speed (let say 200,000 km/sec) the thrust due to this very thin gas is in the order of several Newtons.

A far more imperfect Ion engine can certainly provide 100,000 less thrust by accident at this level of pseudo-vacuum.
« Last Edit: 03/13/2015 05:24 PM by JPLeRouzic »

Offline Notsosureofit

  • Full Member
  • ****
  • Posts: 656
  • Liked: 704
  • Likes Given: 1367
FYI

The 10GHz chamber just arrived ...

Not exactly the profile I would have hoped for but .... as long as I don't get my bells and hammers mixed up ...
« Last Edit: 03/13/2015 06:58 PM by Notsosureofit »

Offline zen-in

  • Full Member
  • ****
  • Posts: 531
  • California
  • Liked: 468
  • Likes Given: 365

I'm probably misunderstanding you, but in the following post, Paul March says:

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329225#msg1329225
"As to why the vacuum test were observing less thrust than in air tests. please note the difference in the RF amps there were driving each test series.  The 30W Mini-Circuit Class-A RF amp was used for the in-air series reported in the 2014 JPC paper, whereas a 100W EMPower Class-A/B RF amplifier was used in the vacuum tests to date. "
Welcome to the discussion
Both amplifiers supply a CW RF pulse to the cavity.  Both drive the cavity with the same kind of drive.   A close analogy would be comparing the sound of a bronze bell when it's hit with a lead hammer vs a hardwood hammer.   The sound is the same.   The step response of a system - be it a circuit, a mechanical system, or almost anything else- is determined by the nature of the system.   I don't believe it is correct to say that subtle differences in the RF drive has resulted in very different responses.    That requires more new science.   

Occam's razor states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected.    The vacuum tests do not show the underdamped response that was seen earlier.   Something was done to mitigate the thrust error caused by the amplifier current generating a torque against the damping magnets.   The picture below shows a large attenuator on what looks like the output of the amp.   This was used possibly to minimize the affects of high SWR.   A high SWR results in the amplifier drawing excessive current.   Earlier posts describe this problem and that the amp had to be returned for repairs.    Something was done to mitigate the thrust error from amplifier current in the vacuum tests.   This attenuator may have been installed for that reason.   With 2 different step responses we are left with the choice of:
1)  Elaborating on the theory of this device further to explain why the system response changes.
2)  Accepting that 2 different experiments have produced results that contradict each other.

Of these two choices Occam requires we choose the one with the fewest new assumptions, which is #2.
« Last Edit: 03/13/2015 07:19 PM by zen-in »

Online Mulletron

  • Full Member
  • ****
  • Posts: 1116
  • Liked: 779
  • Likes Given: 1030
Ok, I got the frustum in the mail today. This is my impartial review. No post purchase rationalization here.

The item was well protected in a sturdy double box with brown paper as padding. I don't expect one receiving a dented frustum if further ones are packaged the same way. Attached are some pics showing zoomed in shots on a 1/16" steel ruler showing tolerances. The machine shop promised me +-1/8" tolerances, he surpassed beat those tolerances. I'm not too concerned about tolerances anyway as I am going to brute force this with a wideband RF source. This cone is unique, and so will be the next one that is built. This is a strength for replication purposes.

I had to push and pull in order to return the frustum to true roundness. It was about 1/8-3/16" out from true round what I got it. I was able to get it round with minor effort. This could be avoided with round rings around the frustum in at least two places, soldered in place, like the one at Eagleworks, with added cost of course. It holds itself true after adjustment. The frustum is nearly as stiff as an aluminum bucket as is. (Think of those ones at Joe's Crab Shack) It takes substantial force to correct it.

The frustum is pictured on my glass top kitchen table, which is extremely flat and true. the frustum sits flush (no rocking, no gaps) against the table on the small and large ends. I flattened out small aberrations in the trueness of the flange (which might cause gaps with the end plate) by drawing the flat edge of a very large/heavy cold chisel handle (in one of the pics) across the copper flange. Copper is very ductile, so minor adjustments are pretty easy.

The butt seam is composed of a 1/2" strip of copper soldered to the outside of the frustum, holding the walls together, allowing a smooth interface inside.

My biggest area of concern is at the ends of the seams, on the inside, there was a very slight bowing in/bending out of the copper. I was able to correct this with some slight pressure from an impromptu tool (a 9" socket extension) which allowed me to flatten it out. The smooth chromed tool didn't make too many tool marks so I'm happy.

The final area of concern is a small air gap (equal to the thickness of the metal) which will form at the seam when the end places plates are clamped in place. A small hole isn't a make or break, but it will bug me (Rf doesn't leak out of holes like liquid does), so I intend to correct for this by using a small 1/4" wide piece of conductive copper tape around/over the gap. I might just drop a bead of solder in there too. Doesn't matter really.

The 16oz copper used in the construction does not deform under its own weight. The inside is smooth and shiny, which is where it counts. The tolerances are pretty tight. I'm happy with it. I don't think I could have done a better job within the first 5 tries at really nuking trying to make one on my own.

In all, I'd give this frustum a 7/10. It is in my opinion capable of being a decent resonant cavity. What would make it perfect is actual heavy gauge flanges and both ends and reinforcement rings, both of which are nice but not necessary. I'm going to be busy over the next several days, installing rf connectors, building a balance and doing a cursory sweep of this with a signal generator at work, looking for its own unique unloaded resonant frequency. In shipping there are sheets of UHMW PE, HD PE, PVDF, PTFE, PP and other stuff to play with. Then I will do loaded characterizations of the frustum.

When all the materials arrive, I am going to hop on here so we can design a test protocol, starting with a Cavendish type gravity experiment in order to characterize the balance. Then the Eagleworks device (as close as we can get). I'm trying to do this all on 2.4ghz ISM band if possible (maybe not the best mode shapes and not optimized, but it is a start). If there is success, then maybe I'll in vest in another RF source.

I am very very anxious that I will be able to find a 2450mhz +-50 mhz resonance with an Eagleworksish loaded frustum, with 2 HD PE 1" discs installed. It is a leap of faith as of now. I am banking on the data Eagleworks gave me and knowing that higher order resonances are there and the number is infinite. I might fall squarely on my face. I need exact solutions!

There is a lot of work to do and challenges to overcome. I want this experiment to be a NSF driven effort. That means I need your expertise. After we get past the "does it move or not" phase, we'll have to do force calculations using what we learned from the balance. I plan to do the gravity experiment first, then replicate the Eagleworks device, the rest is devoted to finding what works and what doesn't (where all the other polymers and Chromium Oxide come in). I will take clear pictures of the products, like the Trilene 4 and 6lb test monofilament line because we need data on these. Going to do 4lb first and 6lb if 4lb fails.

There will be an Internet camera monitoring the action at (url is secret until later....com) Rodal knows. Due to limited bandwidth, the username/password will be shared amongst the top 10 here on the forum. I simply don't have high speed internet where I live overseas. If there is a way to do something like Ustream with my Foscam camera, please let me know so I can make it fully public. This is the best option. It is a technical challenge. Can I push just one stream to a provider and cheaply have them host the live video?? I only have 512k to reliably play with.

Now about the vacuum chamber. I'm not selling a car in order to get a vacuum chamber and I want the cavity chamber walls out of the picture anyway. There will be a dedicated sealed off room for the tests. I am an American living overseas in Italy. Italian houses are rock solid and have no ventilation so the place is stable and there will be no air currents. The test device will be in a box in a box, probably in a box. I have to control for convection in a cheaper/smarter way. Simple as that. If Eagleworks already did vacuum tests, I don't see why it absolutely has to be done every single time. It should work nicely. I'm going to seal the room with zipper doors too.

Lastly, this effort is to crowdsource the answer to a question. It doesn't qualify as an academic institution or a national lab performing research. I have questions. I work with you guys, who also have questions. We each have our strengths and weaknesses, and together I think we are the total package. I'm trying to get others to replicate the Shawyer/Eagleworks/Chinese tests, so I am trying to lead by example. I think this is the goal of many of us on here, to get others to take a look....so it is time to take charge and move on this.

I'm going to messenger the machine shop here in a bit and have him list the thing on Ebay for other replicators who want a way in to testing something with the characteristics of the Shawyer/Eagleworks device. I'll post further details later on. Oh and I have no business affiliation with this guy other than he took my money, and he gave me a copper kettle.





« Last Edit: 03/22/2015 01:31 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
Follow up on thermal effects around the big diameter PCB cap :

I ran simulations on a small simplified model : a 28cm round PCB plate alone in vacuum starting at thermal equilibrium in a 20° surrounding, 35µm copper on top of 1.6mm FR4 support, with copper side uniformly heated by 30W. The model uses 2 discrete layers for copper, and 20 layers for the FR4 support, time step integration of 1µs, running on personal code, first order integrator for heat conduction through plane and radiation losses (as per Stefan-Boltzmann law in T^4).

First run, two first attached pictures : 1600 s of constant power.
We see that on power on it takes many minutes to reach a new thermal equilibrium plateau where the radiative losses equal the constant 30W feed. When this stationary situation is reached, the temperature gradient is constant through the thickness of the PCB as each layer gets as much power from its left as it loses on its right. Comment : this is why it is not possible to interpret the smooth steps in some charts as a reach to some stationary thermal equilibrium, the thermal time constants are above one order of magnitude above the recorded dynamics.

Second run, two last attached pictures : 5s without power, 40 s with power 30W, then off again.
Here on temperatures vs time we will see only the initial situation of previous chart, where the temperatures are not high enough for radiative losses to be significant. In this regimen the various layers just integrate the constant rate of heat, all temperatures are rising near linearly with time, but the outside temperature of the PCB lags after the temperature of copper. Side note, we see on the profile that in this situation far from stationary equilibrium the temperature profile is not a constant gradient through the depth. If we look the difference between temperature copper side and the outer side of the PCB, roughly the gradient, this gradient does exhibit a rise (at power on) and a fall (at power off) with time constants and shapes in the ball park of the frustum's LDS response recorded in vacuum.

This is the green curve, bottom attached image. There is a fast enough but not instantaneous rise to near constant plateau above 1°C difference, and a near symmetric decay. So what ? Well, a gradient of 1°C side from side on 1.6mm thick plate will induce a stress in flexion. If the plate was a thin stripe and not rigidly fixed at the rims it would bend into an arc shape, with a deflection at the belly of L˛/(8*d) * ExpanCoef*(T2-T1) where T2 is hot side, T1 cold side, L the rest length (28cm), d the depth (1.6mm) and ExpanCoef is about 1.3e-5m/m/K (FR4 inplane, neglecting the copper for now). That is around 80µm for 1°C difference.

Obviously for a round plate and not a thin stripe, the stiffness in tangential deformations will lower that quite a bit, and the plate is rigidly linked at its rim, not only in position but also in flexion. So there's still some work to know the exact magnitude and dynamic by integrating those constraints (and the rim will heat differentially too).


Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6045
  • Likes Given: 5325
....
2)  Accepting that 2 different experiments have produced results that contradict each other.
....
Occam's razor states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. 

1) As per above, the experiments are not exactly the same: besides testing in a relative vacuum (6.6*10^(-9) standard atmosphere) vs. one standard atmosphere, there are a number of components that have changed (for example, besides " The 30W Mini-Circuit Class-A RF amp was used for the in-air series reported in the 2014 JPC paper, whereas a 100W EMPower Class-A/B RF amplifier was used in the vacuum tests to date" you yourself point out the following change: " Something was done to mitigate the thrust error caused by the amplifier current generating a torque against the damping magnets.   The picture below shows a large attenuator on what looks like the output of the amp.  ").  Thus, care should be taken to address all the changes when applying classical logic to examine the results.   It is not a question of A) the experiment are exactly the same (this is definitely not the case) or B) the experiments are completely different (this is not the case either), but a case of C) the experiments have many aspects of commonality and a few different aspects (that need to be scientifically addressed).

2) As used in classical logic: "a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical, usually opposite inversions of each other"   Thus contradiction usually implies an inversion of results.  There is no inversion of results here.  Both generate a thrust force, in the same direction under the same geometry and materials.  There is a difference in magnitude between the experiments that needs to be explained. There is a wide range of explanations for these results that do not imply a contradiction.  Non-contradictory explanations comprise the full range of possibilities: from the experiments in atmospheric conditions and the ones in a relative vacuum being both experimental artifacts to both being valid demonstrations of a space thruster.  For example, a non-contradictory explanation is that thermal convection effects were responsible for some fraction of the total measured response in the US, (and a greater fraction in the UK and China due to their use of much higher power), and therefore the magnitude of the measured response in a relative vacuum is smaller.

3) When applying Occam's razor, the focus should be on simplicity overall, as per the original statement of Occam.  Thus, it is not just the number of assumptions but most importantly the simplicity of the assumptions that matter, and of course the overall consistency of the arguments. 



Albert Einstein's famously stated:

Everything should be made as simple as possible, but not simpler.




« Last Edit: 03/13/2015 09:09 PM by Rodal »

Offline flux_capacitor

  • Full Member
  • ****
  • Posts: 563
  • France
  • Liked: 679
  • Likes Given: 927
Does anyone know if this effect scales with the size of the frustum? Could the frequency of the microwaves be adjusted to allow the same level of force in a microscopic frustum that is shown Nasa's macroscopic frustum? If this is the case, would a sequence of many millions of tiny frustums not provide a great deal more force than one large frustum?

Submillimeter-wide multiple terahertz radiation cavities covering the entire structure of the ship, actually being the ship, without any thruster visible. What an interesting and provoking thought!

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6045
  • Likes Given: 5325
Does anyone know if this effect scales with the size of the frustum? Could the frequency of the microwaves be adjusted to allow the same level of force in a microscopic frustum that is shown Nasa's macroscopic frustum? If this is the case, would a sequence of many millions of tiny frustums not provide a great deal more force than one large frustum?

Submillimeter-wide multiple terahertz radiation cavities covering the entire structure of the ship, actually being the ship, without any thruster visible. What an interesting and provoking thought!


Quote from: MIT News
What these satellites lack is a viable propulsion system, says MIT aeronautics and astronautics alumna Natalya Brikner PhD ’15, co-founder and CEO of Accion Systems. “You can make a satellite the size of a softball with a surprising amount of capabilities, but it can’t maneuver properly and falls from orbit quickly,” she says. “People are waiting for a solution.”
Now Accion has developed a commercial electrospray propulsion system — their first is about the size of a pack of gum — made of tiny chips that provide thrust for small satellites. Among other advantages, Accion’s module can be manufactured for significantly less than today’s alternatives.
This technology could enable low-cost satellites, such as those known as “CubeSats,” to become more viable for various commercial and research applications, including advanced imaging and communications, where numerous satellites could provide global coverage. “That requires propulsion, but something so small that it won’t interfere with the small volume and resources a small satellite already has,” says Accion technical advisor Paulo Lozano, an associate professor of aeronautics and astronautics who invented the underlying technology.

http://newsoffice.mit.edu/2015/accion-systems-thruster-for-small-satellites-0311#.VQGgo9sCC8A.linkedin

http://www.leonarddavid.com/tiny-thruster-offers-big-promise/

http://newsoffice.mit.edu/2012/microthrusters-could-propel-small-satellites-0817











« Last Edit: 03/14/2015 01:03 AM by Rodal »

Offline zen-in

  • Full Member
  • ****
  • Posts: 531
  • California
  • Liked: 468
  • Likes Given: 365
....
Occam's razor states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected.    The vacuum tests do not show the underdamped response that was seen earlier.   Something was done to mitigate the thrust error caused by the amplifier current generating a torque against the damping magnets.   The picture below shows a large attenuator on what looks like the output of the amp.   This was used possibly to minimize the affects of high SWR.   A high SWR results in the amplifier drawing excessive current.   Earlier posts describe this problem and that the amp had to be returned for repairs.    Something was done to mitigate the thrust error from amplifier current in the vacuum tests.   This attenuator may have been installed for that reason.   With 2 different step responses we are left with the choice of:
1)  Elaborating on the theory of this device further to explain why the system response changes.
2)  Accepting that 2 different experiments have produced results that contradict each other.

Of these two choices Occam requires we choose the one with the fewest new assumptions, which is #2.....
Occam's razor states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. 

1) As per above, the experiments are not exactly the same: besides testing in a relative vacuum (6.6*10^(-9) standard atmosphere) vs. one standard atmosphere, there are a number of components that have changed (for example, besides " The 30W Mini-Circuit Class-A RF amp was used for the in-air series reported in the 2014 JPC paper, whereas a 100W EMPower Class-A/B RF amplifier was used in the vacuum tests to date" you yourself point out the following change: " Something was done to mitigate the thrust error caused by the amplifier current generating a torque against the damping magnets. 

2) As used in classical logic: "a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical,

3) When applying Occam's razor, the focus should be on simplicity overall,



If the Eagleworks device was actually producing a thrust the STP and vacuum test would have been very similar.   The reason for doing a vacuum test was to show the device worked the same in a vacuum and that the results were not because of air currents, etc.   This concept of achieving consistent results is common to many activities.   If for example you had two FFT programs and they gave you different results for the same input where would you be?   So this is an important concept for theoreticians.    People who get their hands dirty doing experiments, writing software, or designing hardware have the same goal of achieving consistent results.   Without it you have no benchmark to measure success.

Using a different RF amp and adding an attenuator would not change the basic nature of the test.   They are applying an RF pulse of predetermined frequency and power level to the cavity.    What determines the step response of the system is the TP, what it is loaded with, and what kind of damping it has.   

The Aug. 2014 AIAA paper presented several thrust waveforms as evidence of an anomalous thrust.    Taking the Eagleworks team at their word we have examined these thrust waveforms and noted they have an overshoot, ringing, and an undershoot.   This is entirely a function of the TP, its damping, etc.   The same response is seen with the capacitor calibrator and a similar response is seen with the Cannae drive.   Earlier an error thrust waveform was also shown.   This error waveform was acquired when the dummy load was used.   Further tests subtracted this error waveform.   It also had the same overshoot, ringing, and undershoot (underdamped) as all the other waveforms.

The thrust waveforms from the vacuum test are not underdamped like the earlier thrust waveforms.   However the calibration waveform in the same picture does have an underdamped response.   It appears to me that by mitigating the error thrust in some way the underdamped characteristics have been removed from the thrust waveform.   From this I conclude the earlier thrust waveforms were actually error waveforms that were not corrected for because the amplifier current was higher during the test runs than it was when the correction factor was acquired (the dummy load test).    This is a logical inference which I understand some people may not want to accept.   But the fact remains the two set of experiments have produced inconsistent results.

The vacuum tests resulted in very different waveforms.   Thrust continues the after RF is off.   This is very unusual.  How is momentum stored in the cavity?   The earlier tests didn't show this.

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation. 
« Last Edit: 03/14/2015 05:45 AM by zen-in »

Offline DIYFAN

  • Member
  • Posts: 48
  • Liked: 28
  • Likes Given: 149
An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.

While I generally agree with you, I've been around long enough to know that unless you decide to try something for yourself, it is difficult to gain a true understanding.  Perceiving what is real in a world awash with conjecture, theories, political agendas, financial agendas, greed, and outright lies, is quite a challenge (not accusing anyone on this forum of such things, just commenting in a generalized manner). 

So how does one gain a sure knowledge?  Attempt a replication.  Measure it for yourself.  Convince yourself that it works or doesn't work.  The materials are not cheap, but they are also not super expensive, and are very attainable.  Don't have all of the expertise needed?  Find a friend or co-worker who might.  Don't have the time?  Cut down on some other optional activities.  Don't have the motivation?  Can't really help there, but there are some great self help books out there. 

If we can get say 10 people attempting replications of the general concept and selflessly willing to share their results, imagine how much data can be aggregated and shared among the group.  Imagine where we could take this if the effect is real.  And if the effect cannot be shown and cannot be reproduced after diligent efforts, then that is also a good contribution to the store of human knowledge as well.
« Last Edit: 03/14/2015 05:29 AM by DIYFAN »

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
While replication attempts by DIYers might add very valuable data and insight into the measured effects, there is also a lot that has been made and still can be made by community around models and simulations, thanks to the data published from Eagleworks and some answers later shared by Paul March.

It didn't took building and launching a specifically instrumented clone of pioneer probe to resolve (classically) the pioneer anomaly, it took "only" a reasonably accurate model from known parameters and integrating some relevant classical phenomenons in a simulation to get a convincing qualitative and quantitative explanation of the anomaly. As always, a number of people will find those results not convincing enough and will cling to exotic extensions of physics indefinitely... a classical explanation is less fun obviously, but reality isn't necessarily fun or exciting.

For recall we have a thermal gradient across the thickness of PCB big end cap that has a dynamic that smoothly follows microwave power pumped into the system, see attached picture. The situation is close enough to that of a bimetallic strip, also here it is the difference in temperature across the thickness rather than the difference of thermal expansion that would drive thermal constraints. Also this is not a strip but a round membrane. Anyway, thermal gradient implies stress implies deformations implies more or less proportional CoMPosition(t) shifts. Exact shape and magnitude of which remains to be assessed from thermo-mechanical model of frustum, including PCB cap and supporting rim and copper cone, taking into account gradients across thickness.

Since the apparatus is tilted enough that the tilt plays a role in the stability of pendulum's arm at rest equilibrium, we also have LDS_reading(t)=cst1*Thrust(t)+cst2*CoMPosition(t) where cst1 and cst2 are in the same ballpark. Meaning that a CoMPosition(t) signal alone can explain a step for LDS_reading(t) even while Thrust(t) is 0 and remains 0.

Am I seriously saying those two ideas taken together can account for the major part of what is interpreted as thrust pulses ? Yes, this is seriously close enough to a viable explanation that it deserve further inquiry. But I'm reaching my limits in terms of simulation tools...

« Last Edit: 03/14/2015 01:46 PM by frobnicat »

Offline Star-Drive

  • Member
  • Full Member
  • ****
  • Posts: 829
  • TX/USA
  • Liked: 876
  • Likes Given: 9
....
Occam's razor states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected.    The vacuum tests do not show the underdamped response that was seen earlier.   Something was done to mitigate the thrust error caused by the amplifier current generating a torque against the damping magnets.   The picture below shows a large attenuator on what looks like the output of the amp.   This was used possibly to minimize the affects of high SWR.   A high SWR results in the amplifier drawing excessive current.   Earlier posts describe this problem and that the amp had to be returned for repairs.    Something was done to mitigate the thrust error from amplifier current in the vacuum tests.   This attenuator may have been installed for that reason.   With 2 different step responses we are left with the choice of:
1)  Elaborating on the theory of this device further to explain why the system response changes.
2)  Accepting that 2 different experiments have produced results that contradict each other.

Of these two choices Occam requires we choose the one with the fewest new assumptions, which is #2.....
Occam's razor states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. 

1) As per above, the experiments are not exactly the same: besides testing in a relative vacuum (6.6*10^(-9) standard atmosphere) vs. one standard atmosphere, there are a number of components that have changed (for example, besides " The 30W Mini-Circuit Class-A RF amp was used for the in-air series reported in the 2014 JPC paper, whereas a 100W EMPower Class-A/B RF amplifier was used in the vacuum tests to date" you yourself point out the following change: " Something was done to mitigate the thrust error caused by the amplifier current generating a torque against the damping magnets. 

2) As used in classical logic: "a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical,

3) When applying Occam's razor, the focus should be on simplicity overall,



If the Eagleworks device was actually producing a thrust the STP and vacuum test would have been very similar.   The reason for doing a vacuum test was to show the device worked the same in a vacuum and that the results were not because of air currents, etc.   This concept of achieving consistent results is common to many activities.   If for example you had two FFT programs and they gave you different results for the same input where would you be?   So this is an important concept for theoreticians.    People who get their hands dirty doing experiments, writing software, or designing hardware have the same goal of achieving consistent results.   Without it you have no benchmark to measure success.

Using a different RF amp and adding an attenuator would not change the basic nature of the test.   They are applying an RF pulse of predetermined frequency and power level to the cavity.    What determines the step response of the system is the TP, what it is loaded with, and what kind of damping it has.   

The Aug. 2014 AIAA paper presented several thrust waveforms as evidence of an anomalous thrust.    Taking the Eagleworks team at their word we have examined these thrust waveforms and noted they have an overshoot, ringing, and an undershoot.   This is entirely a function of the TP, its damping, etc.   The same response is seen with the capacitor calibrator and a similar response is seen with the Cannae drive.   Earlier an error thrust waveform was also shown.   This error waveform was acquired when the dummy load was used.   Further tests subtracted this error waveform.   It also had the same overshoot, ringing, and undershoot (underdamped) as all the other waveforms.

The thrust waveforms from the vacuum test are not underdamped like the earlier thrust waveforms.   However the calibration waveform in the same picture does have an underdamped response.   It appears to me that by mitigating the error thrust in some way the underdamped characteristics have been removed from the thrust waveform.   From this I conclude the earlier thrust waveforms were actually error waveforms that were not corrected for because the amplifier current was higher during the test runs than it was when the correction factor was acquired (the dummy load test).    This is a logical inference which I understand some people may not want to accept.   But the fact remains the two set of experiments have produced inconsistent results.

The vacuum tests resulted in very different waveforms.   Thrust continues the after RF is off.   This is very unusual.  How is momentum stored in the cavity?   The earlier tests didn't show this.

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation. 

Zen-in:

"The thrust waveforms from the vacuum test are not underdamped like the earlier thrust waveforms.   However the calibration waveform in the same picture does have an underdamped response.   It appears to me that by mitigating the error thrust in some way the underdamped characteristics have been removed from the thrust waveform."

The various dummy load tests have never been performed in a vacuum, only in-air, so the dynamic response of the torque pendulum (TP) for these dummy load tests will always look like the in-air TP examples.  I suppose we could run the dummy load test in vacuum as well just for consistency, but there are so many other things to do in this business, that it didn't seem a wise use of time and resources.

BTW, our COMSOL thermal analysis of the copper frustum operating in-air indicated that there was a thermally induced air circulation primarily generated by the large-OD face of the frustum due to its much higher change in temp than the small OD end-cap.  This air circulation over the vertical wall of the large OD of the frustum creates a low pressure zone over the large OD end-cap that pulls the frustum towards the large-OD side of the frustum which subtracts from the frustum's normal thrust generation force vector.  We think that this is why for a given input power and the TM212 resonant mode that the in-air thrust measurements are ~2.5X smaller than the in-vacuum cases.   

Lastly find attach a slide with the results of this week's test that demonstrate that the copper frustum still generates a thrust signature when it is not in the stainless steel vacuum chamber walls.  And as you will note the forward thrust signature is similar in magnitude for the same 50W case in-air in the vacuum chamber, so I think we can start to put to bed the idea that standard E&M evanescent waves interactions with the vacuum chamber walls are the cause of these thrust signatures.

Best, Paul M.

Offline Star-Drive

  • Member
  • Full Member
  • ****
  • Posts: 829
  • TX/USA
  • Liked: 876
  • Likes Given: 9
Dr. Rodal:

Looking over some of our test results from last spring and summer just now, I realized that I had forgotten to provide this forum a few test runs at some of the other resonant modes we've looked at that used different dielectric discs and locations including polycarbonate which I hadn't mentioned before.  These examples are attached and you will note that these other copper frustum resonant modes (TM010 & TE012) have very different thermal torque pendulum responses than the TM212 (your TM221 I think) cases we've discussed of late.  That fact might be of importance when discussing whether these thrust signals are real or just artifacts...

PS: The magnitude of the torque pendulum's overshoot is directly related to what version of the magnetic damper that was used for the particular test in question and how thick the copper damper blade was at the time.  At the moment we are using an arrangement that is slightly over-damped in an attempt to smooth out some of the pesky low frequency seismic noise in the system.

DPS:  The magnitude of the RF amp's dc current induced thrust signal offset is directly related to how much leakage current is going through the torque pendulum's steel torsion bearings.  As I became aware of this problem over the last year, I've found various ground wiring tricks to mitigate this dc current induced negative going offset, but I've never found a way to get rid of all of it.

Best, Paul M   
« Last Edit: 03/14/2015 02:51 PM by Star-Drive »
Star-Drive

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6045
  • Likes Given: 5325
... have very different thermal torque pendulum responses than the TM212 (your TM221 I think) cases we've discussed of late.  That fact might be of importance when discussing whether these thrust signals are real or just artifacts......
Thanks Paul.  Great reply with quantitative, factual, objective, helpful information.   :)


Clarification: concerning your designated TM212 mode which I interpret as TM222 we completely agree on what the mode looks like (this is the most important thing, besides any convention for designation), and we agree that it is transverse magnetic, and we agree that the azimuthal mode number should be designated m=2 and we agree that the longitudinal mode number should be designated p=2.  We only differ on how "n" (on TMm n p) should be designated: your designation is n=1 while my designation is n=2.
« Last Edit: 03/14/2015 03:44 PM by Rodal »

Online Mulletron

  • Full Member
  • ****
  • Posts: 1116
  • Liked: 779
  • Likes Given: 1030
While researching, I found @Rotosequence found this clue first:

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1321774#msg1321774

Gotta give credit where credit is due.
Challenge your preconceptions, or they will challenge you. - Velik

Tags: