Rodal:QUESTION: Why did you use a glass-fiber-reinforced polymer printed circuit board as the end plate ? << 0.063 inch thick FR4 printed circuit board with 1.0 oz copper, (~35 microns thick of Cu epoxied to the FR4 fiberglass)>>3) Why not get rid of the fiber-reinforced-polymer printed circuit board and just simply use a 1/4 inch thick (0.25 inches) copper plate for flat ends to prevent this thermal instability, and hence eliminate this artifact from consideration ?Answer: I used the FR4 PCB with 1.0oz copper end-plates to minimize payload mass while maximizing the thrust to weight ratio of the copper frustum assembly AND the signal to noise ratio of the torque pendulum system. I used the 1.0oz copper thickness because the ac skin depth of RF at 1.5 GHz is about 2.0 microns, so 5X that depth or 10 microns of copper should contain 99% of the ac currents at this frequency. And I still had an additional 25 microns of copper thickness as non-current carrying thermal mass to stabilize its performance. Now if you care to look at my pictures of the large OD end of the Eagleworks copper frustum, the mass of the entire frustum assembly without the PE discs is listed as 1.606 kg. Your 0.25" thick solid copper end plates would add over 3.0 kg of dead mass to this figure just for the small and large OD ends plates and cost us $333.50 for a 12"x 24"x0.25" copper plate stock from McMaster-Carr needed to make them. As I've said before we have tried aluminum angles and even 0.090" thick AL plates across the existing PCB end caps and noticed no change in its performance except for the increase in seismic noise pickup that the extra mass such payload-mass increasing modifications always bring to the table.Best, Paul M.
This is an op ed. Putting this all in perspective, the successful measurement of a thrust signature in hard vacuum helped me gain real confidence that the Emdrive and Cannae* are in fact producing a real thrust signature which begs explanation. For now it appears to work, but barely. Not enough to make people take notice, even though it works >6000x better than a photon rocket. This has potential to be HUGE. It would be irresponsible to not take this seriously now. Yes this is high risk, but it is also very high reward. I've been reading about crowdsourcing science lately after hearing a piece about it on the SGU podcast. Wouldn't it be nice if we could crowdsource research into the Emdrive. I'm thinking crowdsourcing because there is a taboo associated with this subject. Because it is assumed to go against established scientific concepts. Academic institutions and professionals would no doubt be hesitant to publicly acknowledge involvement in such research, without sufficient evidence this is real. Put another way, they won't touch it until someone before them assumes the risk first. BZ to Eagleworks for having the courage to at least take a look. This is the public attitude, but if you really examine the literature, Emdrive can be explained via established principles and only serves as experimental evidence supporting the quantum foundations of reality. As I've said, this isn't just some neat thruster, if it works it is also an instrument which could give immense insight into the nature of space and time itself. We really need contributions from experts in optics, materials science and QFT, with open minds. If we go the crowdsource route, we need a platform and we need leadership. Just like the hyperloop. This problem is to be figured out or put to rest. I have confidence that Eagleworks can eventually figure this out, but at the same time, we need to provide forceful backup**. The last thing we need is for this potential world changing technology to fall prey to an unworkable theory which leads to no results and time running out***. I know this sounds harsh, and I mean no disrespect. Do we want to be famous or correct? Both have to be true, to be true. In this writer's opinion, this is exactly what happened to ME. The inability or unwillingness to adapt one's theory in the face of new information and scrutiny. Can you imagine the space flight applications that could come from this potential technology, if it is in fact a reality and we can figure it out? Can you imagine what could have happened if we had not let it slip through the cracks for several more years? We (humanity) need to slough off our scientific hubris. We don't know everything yet; we only think we do. Quoting the controversial Rupert Sheldrake, "The science delusion is the belief that science already understands the nature of reality in principle, leaving only the details to be filled in. This is a very widespread belief in our society........." He is pointing out our hubris, how we think we know it all already, even as we are such a young, immature species. We don't know jack. Our collective ego surpasses our wisdom. The insight to be gained from our universe is as infinite as the universe itself, our comprehension is unfortunately finite.http://www.nbcnews.com/tech/innovation/hyperloop-may-become-crowdsourced-reality-within-decade-n272116http://www.usatoday.com/story/news/nation/2014/07/25/ozy-crowdsourcing-science/13143465/http://www.nextscientist.com/3-examples-crowdsourcing-science/http://www.abc.net.au/news/2014-09-10/crowd-sourced-research-more-trouble-than-it-is-worth-study/5734444*We need to analyze Emdrive and Cannae equally; eg does thermal instability hold for both?**Naval leadership concept *** http://arxiv.org/pdf/1411.5359v1.pdf (the QVPT model has officially "got served")
Dr. McCulloch has derived a new expression taking into account the three-dimensional nature of the truncated cone EM Drive and constructed a new comparison table. P=Power InputQ=Quality Factor of Resonancec=speed of lightwb=Big Diameterwc=Small DiameterL=LengthThe McCulloch thrust (F), was (2-D expression)F = PQL/c * (1/wb - 1/ws) (1)and it is now (3-D expression)F = 6PQL/c * ( 1/(L+4wb) - 1/(L+4ws) ) (2)Seehttp://physicsfromtheedge.blogspot.com/2015/02/mihsc-vs-emdrive-data-3d.html
Has anyone here considered a kickstarter campaign?
...Do we have a complete set of data like Mike's table, including mode numbers ?
I've been reading this thread with great interest, and thank you all for all the information you brought. (i've learnt a bunch of things and been happy to read back my physics courses again)BUT: I don't understand why the simplest explanation here:http://forum.nasaspaceflight.com/index.php?topic=29276.msg1293349#msg1293349NASA'S MICROWAVE PROPELLANT-LESS THRUSTER ANOMALOUS RESULTS: CONSIDERATION OF A THERMO-MECHANICAL EFFECT wouldn't explain all the results obtained so far (in ambiant air pressure and in a lab's vacuum)Is there a need to find other complicated explanations before this one is proven wrong ?
Either this : sharp stop of displacement at power-off, sharp thrust opposite to initial direction. ----- | |...------- | --------... | --- | -- -Or this : gentle stop of displacement at power-off, harder to see but implies higher total integrated displacement (many centimetres) ----- | |...------- | ----... ---------- While what is observed looks like a net imbalance (more above the baseline than below) ----- | |...------- --------------...
Quote from: MathieuA on 02/14/2015 08:31 amI've been reading this thread with great interest, and thank you all for all the information you brought. (i've learnt a bunch of things and been happy to read back my physics courses again)BUT: I don't understand why the simplest explanation here:http://forum.nasaspaceflight.com/index.php?topic=29276.msg1293349#msg1293349NASA'S MICROWAVE PROPELLANT-LESS THRUSTER ANOMALOUS RESULTS: CONSIDERATION OF A THERMO-MECHANICAL EFFECT wouldn't explain all the results obtained so far (in ambiant air pressure and in a lab's vacuum)Is there a need to find other complicated explanations before this one is proven wrong ?From what I understand (Rodal please correct me if wrong as I may have skimmed that too fast) the thermal buckling can very well explain the initial steep step thrust response to power-on. The steepness of the initial measured thrust on power-on were used as an argument by Eagleworks to rule out any thermal effect (as any thermal effect was supposed too slow to explain the sharp rise). Rodal's work shows that a thermal effect is not ruled out as far as initial steep rise is concerned : thermal buckling can account for the magnitude and rate of the initial rise (same ballpark).The question remaining is the sustained level of apparent thrust after the rise, sustained for 35 or 40 s at approx. constant magnitude. I'm not sure this was tackled and ruled out as possibly being produced by pure thermal buckling/dilatation explanation but my feeling (shared ?) is that it is hardly possible. A constant thrust of 50µN for 40s means a mass of 1kg (out of my hat, ballpark of heated mass) accelerating at constant a=F/m=50e-6 m/s² during the thrust plateau of 40s, that is an integrated displacement of (some mass of 1kg relative to rest of the frustum + balance arm) x=0.5 a t² = 4 cm (more than an inch).Also to have a (more or less) nice fall to flat baseline at power-off (as observed) would mean this moving mass would stop accelerating but continue at its gained velocity (relative to rest of frustum + balance arm) and ideally stop very gently, at opposite acceleration with magnitude much lower than the previous one. This continuation of movement would add even more to the total displacement, I'd say a few times 4cm (like 10 or 20 cm...). Otherwise if the moving mass where to stop quickly at power-off, we would observe a sharp fall of the thrust signature much below the initial 0 baseline. Generally you could tell such "thrust from displacement of one part of the drive relative to another part of drive (1)" by seeing a 0 net thrust when integrating during the power-on and well after the power-off : you would see a part above the baseline (power-on period) and a part below (after power-off) and the later would cancel the former. Either this : sharp stop of displacement at power-off, sharp thrust opposite to initial direction. ----- | |...------- | --------... | --- | -- -Or this : gentle stop of displacement at power-off, harder to see but implies higher total integrated displacement (many centimetres) ----- | |...------- | ----... ---------- While what is observed looks like a net imbalance (more above the baseline than below) ----- | |...------- --------------...It would certainly be possible to hide a moving mass inside the frustum, with a system to make it move the right displacement (many cm) to mimic a thrust signature with apparent net imbalance as seen from the outside (for not too long after power-off and with a "drifting baseline" to blur the opposite thrust period), but it's hard to see how such a huge displacement could happen by accident or stay unnoticed by experimenters. I would say that a thermo-mechanical effect involving a simple linear displacement of some driver's part mass is rather well ruled-out as an explanation for the sustained part (40 s) and early after decay of the signal. Maybe some more complex classical explanation might still apply.(1) by "drive" I consider the whole system mounted on the balance's arm and the arm itself
Rodal & Crew.There is a major problem with your explanations of the copper frustum's "thrust" traces being strictly due to the frustum's large OD end-cap's immediate inward oil-canning to the left, see attached thermal expansion diagram, which is then followed by the copper frustum's longer-term thermal expansion to the left of its 0.024" thick copper cone material. And this problem is that these thermal effect explanations for the generated torque pendulum (T.P.) movements are in the wrong direction to account for the observed thrust traces. I.e., they are fighting the observed thrust traces, not adding to or creating them.Now Newton's third law still states that for every action there is an equal and opposite reaction. So when the copper frustum's large OD end-cap's prompt and inward oil canning action, followed by the slower frustum cone thermal expansions, they both push the copper frustum's Center of Mass (CoM) to the left as viewed from the front of the Eagleworks' vacuum chamber looking back at the test article and torque pendulum, while noting how the copper frustum is bolted on to the T.P.. These thermally induced actions to the left requires the torque pendulum's arm to move to the right to maintain the balance of the torque pendulum's arm in the lab's 1.0 gee gravity field, since we also use the Earth's g-field to help null the pendulum's movements. However the observed up-going in the Y-axis thrust traces, see attached 50W slide, require the T.P. to move to the left, whereas the thermal expansion induced left-going CoM actions require the T.P. to move to the right, which should REDUCE and modify over time the magnitude of the observed thrust signal coming from the copper frustum actions of accelerating QV plasma to the right and out of the frustum. And you can see this negative longer term frustum thermal drift by noting the downward going baseline slope of the thrust trace even after the RF power is removed from the copper frustum. Best, Paul M.
@Rodal -Its easy to overlook items when there is a lot of new data to evaluate, but Thrust is to the left. See attached.
What about Cannae? It has completely different construction. Thrust was measured from it too. How does buckling explain Cannae? ...