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.
Quote from: frobnicat on 03/12/2015 07:08 pm....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:....
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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.
Quote from: zen-in on 03/13/2015 05:39 amQuote from: frobnicat on 03/12/2015 07:08 pm....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
Quote from: frobnicat on 03/12/2015 07:08 pm....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.
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.
Quote from: Rodal on 03/13/2015 12:29 pmQuote from: zen-in on 03/13/2015 05:39 amQuote from: frobnicat on 03/12/2015 07:08 pm....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 NeumannQuoteThe 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. 157While 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.
Quote from: zen-in on 03/13/2015 05:39 amQuote from: frobnicat on 03/12/2015 07:08 pm....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 NeumannQuoteThe 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
Quote from: frobnicat on 03/12/2015 07:08 pm....It's amazing how long this discussion has gone on. ....There are several observations that can't be disputed:....
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
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. "
....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.
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?
Quote from: Polonius on 03/12/2015 06:38 pmDoes 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!
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.
Quote from: zen-in on 03/13/2015 06:30 pm....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,
....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.
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.
Quote from: Rodal on 03/13/2015 07:38 pmQuote from: zen-in on 03/13/2015 06:30 pm....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.
... 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......