Ok, despite my best efforts (which, admittedly are rather feeble), I can no longer tell what 'frobnicat' is attempting to accomplish. Is he arguing that all of the 'thrust' produced by this device is some sort of thermal artefact? From what I can tell, the goalposts seem to have moved at least once.Executive summary time, please.
Quote from: frobnicat on 03/15/2015 09:35 pm....I wanted to show that the measured "force" (LDS reading really) might not be a force at all, but a change in equilibrium rest position, as per the diagram showing how the equilibrium rest position is different depending on test article CoM position...Sorry again for not recalling your prior posts and needing a brief summary.QUESTION1: have you calculated the change in Center Of Mass position for these different cases? (yes or no ?) if your answer to QUESTION1 is no, stop reading.
....I wanted to show that the measured "force" (LDS reading really) might not be a force at all, but a change in equilibrium rest position, as per the diagram showing how the equilibrium rest position is different depending on test article CoM position...
if your answer to QUESTION1 is yes, then,QUESTION2: do your calculations for the change in center of mass position give a displacement that is close to the displacement vs. time measurements at NASA Eagleworks?
Quote from: Rodal on 03/13/2015 12:29 pmObservation #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 atmosphereIf 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.
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
...Er, yes, no, this is in progress but would need a simulation with professional level tools I haven't knowledge of to be assessed with any certainty...It could.At least it needs to be properly assessed before it can be ruled out. ...
...Suppose (for argument's sake) that your conjecture for shifting center of mass due to thermal expansion could explain the measured response in one direction, which will call the "forward" direction.Then, how could it possibly explain the measured response in the opposite direction, with the experimenters able to put the EM Drive into "reverse" at will?
... a picture of the new heat shields for our torque pendulum's upper and lower torsion springs, (more belts and suspenders to mitigate thermal drifts in the TP baseline), the reversed test setup drawing and the best reversed thrust plot obtained just before or during when our second and last 120W max RF amplifier was dying from internal corona discharges around its RF output circulator.
1) Do you agree that the only serious data we have about "reverse" is in fact just a 180° turn of test article ?2) That a 180° turn of the test article will reverse a thermal effect as much as it reverses a thrust ?
..we don't have precise data concerning a situation where some sustained level of apparent thrust would be toward the big end of test article ? I do recall some mention by Paul March to such thrust toward big end was made, would appreciate if you or anyone find that.
I do agree that precise and consistent data on point 4 [Reverse tests data] would indeed nullify a lot of my conjectures.
FYIhttp://scitechdaily.com/researchers-hope-to-provide-new-insights-into-quantum-gravity/But, it's a spherical cavity.......
...1) Please refer to the image I provided: of a car's shift mechanism, showing a REVERSE shift. I certainly do NOT consider turning the EM Drive around by 180 degrees to equate "running in reverse", any more than turning a car engaged in "D" (or in 1st shift) around by 180 degrees would make it run in reverse: the car would still run FORWARD (but in the opposite direction).
Reverse, as indicated by the graph I provided refers to going backwards: a car's reverse ! That's why I attached the huge image showing a car's reverse shift (the significance of the "reverse" R cannot be misconstrued )
2) Of course, "That a 180° turn of the test article will reverse turn a thermal effect as much as it reverses turns a thrust ?"So what ?
...Your post above questions whether the EM Drive can be run in reverse. You state:Quote from: @frobnicat..we don't have precise data concerning a situation where some sustained level of apparent thrust would be toward the big end of test article ? I do recall some mention by Paul March to such thrust toward big end was made, would appreciate if you or anyone find that.@Mulletron [hat tip for being the first one in the thread to use the car's reverse shift image] has a number of posts also interpreting that the EM Drive had been run in reverse, for example certain modes run the EM Drive forward and certain modes run the EM Drive in reverse. One can, in principle, then run the EM Drive in reverse, at will, by "turning the (virtual) knob" of the exciting frequency such as to excite a natural frequency that has a mode shape such as producing an EM Drive's thrust in reverse
I will let Paul March:1) describe how else the EM Drive can be run in reverse at will [using the literal definition of "reverse"].
2) determine whether my interpretation of the "reverse" measurement of -9.9 microNewtons is indeed a reverse thrust measurement (my interpretation was based on a literal interpretation of the word "reverse") or whether it is a measurement with the EM Drive turned around by 180 degrees (your interpretation). The image for "reverse" shows the same frequency as for the "forward" images, so if the frequency is correct it means that it was run in the same mode shape both forward and backwards. Either A) you are correct that the image is really not an EM Drive in reverse (but instead it is the EM Drive turned around and still running forward), or B) if it is indeed running in reverse it must have been accomplished by some other means, other than by changing frequency.
3) if my interpretation of the image showing "reverse" measurement of -9.9 microNewtons was NOT a reverse thrust measurement, but instead was forward thrust with the EM Drive turned around 180 degrees, then could Paul March please point out to where is the data for the EM Drive run in Reverse.
PS: No need to warn about "absurd controversies" or about "indulging ourselves." Such warning (and your discussion about turning the EM Drive around by 180 degrees) was unnecessary if you take into account 1) the definition of the word reverse, and 2) the image I provided of the car's shift mechanism showing a Reverse shift. The meaning of "R" reverse in a car cannot be misconstrued.
No need for us to get upset about this. It is important to settle this issue, as you recognize:Quote from: @frobnicatI do agree that precise and consistent data on point 4 [Reverse tests data] would indeed nullify a lot of my conjectures.
The thrust waveforms have changed significantly in the past few months. The first picture below is from April 2014. 19.9 Watts of RF power resulted in a peak thrust of 105 microNewtons. There is no mention what the error thrust due to magnetic interaction is however. The waveform has a fast rise time and has an overshoot and other characteristics of an underdamped response. It is very similar to the calibration drive and the error thrust.The next thrust waveform, in a vacuum, is very different. I think it is the result of a long duration thermal effect and doesn't indicate any thrust at all. With 50 Watts and a vacuum surrounding the cavity a thermal response would be expected.The reverse test, also with 50 Watts, brings us back to the underdamped response, but at a very low level.With no consistency in any of these data the only thing anyone knows for sure is:1) Heat is being dissipated in the cavity.2) DC current near a magnet generates torque.
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
I disagree that "reverse" only means to move backwards, so may I suggest that a different description such as "flipped", "turned around" or "rotated" be used to better describe the experimental setup, especially given the potential for there to be a way to change the directionality electrically (and if that is true then perhaps we could follow the circuit symbol for a cell to help us communicate such directionality i.e. thrust towards the big end is positive; small end is negative)
...
one can also reverse this thrust vector for this copper frustum by just changing which excited resonant mode is used
All:Sorry I didn't make the time to participate in this ME-Drive forum for the last 6-to-8 months up, but I will try to catch up with everyone else in due course. That said lets try to answer the questions that popped up since my morning post.1. I was not the lead author for the Eagleworks' 2014 AIAA/JPC paper and in fact I only supplied pictures and data for same during that period because Dr. White thought that my time was best spent in the lab gathering data instead of report writing. Thus some of the details that Dr. Rodal is looking for may have been lost or garbled in the report writing by the others on the author list.2.0 The thrust vector for the four resonant modes examined in detail, (the cavity's fundamental TM010, TE012, TM211 & TM212 for our copper frustum is normally in the frustum's large OD to small OD direction for most, but not all the E&M resonant modes checked. However, one can also reverse this thrust vector for this copper frustum by just changing which excited resonant mode is used and/or mounting the dielectric discs at the large OD end of the cavity instead of the small OD end, see attached resonant mode map. Sorry, but a one size fits all solution to this EM-Drive thrust direction is not available in this venue because of the importance of the ExB phase relationship of the expressed Lorentz forces between the excited E&M fields and the possible dielectric and QV plasma flow phenomenon that may be at work in each resonant mode expressed. That is why this type of E&M thruster is so hard to get a handle on, for there are far too many degrees of freedom in the system to track let alone directly control. 3. The Eagleworks vacuum chamber's main body is made from 304L stainless steel while its swing out door is made from aluminum. Most of the nuts and bolts in the vacuum chamber are also made from 18-8, 304 or 316 stainless steel alloys. Now to try to answer Dr. Rodal's specific questions:"1) In the NASA experiments the truncated cone's center of mass moved towards the [ ? ] diameter end (where ? stands for big or small)"For the TE012 and TM212 excited resonant modes, our copper frustum's center of mass moved toward the small OD end of the frustum when RF power was applied to the copper frustum."2) In the NASA experiments, we at NASA Eagleworks define the thrust force direction to be in the [? ] direction as the movement of the truncated cone's center of mass (where ? stands for same or opposite)"For just the TE012 & TM212 excited resonant modes, the thrust force direction AKA thrust vector was observed to be in the same direction as the movement of the frustum's center of mass when RF power was applied to the frustum's magnetic loop antenna. If I missed a question along the way keep asking, but I'll be in and out of the house for the rest of the day, so I may not get to answer them until late this evening or tomorrow afternoon USA based CST.Best, Paul M.