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#1480 by rfmwguy on 22 Apr, 2016 00:58
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I just asked a seller if their 0.03 was solid core or coiled. Poor descriptions for the most part.
Thank you. I've looked around for this type of wire, if you see something, I'd appreciate a link. So many welding wires to sort through.
The wire hasn't been selected yet, need about 15 lbs total weight support (don't know exactly yet). Rather than a torsion estimate, was planning on actual weight displacement calibration for horizontal deflections measured by the laser displacement sensor...40 MM +/- 10 MM range with micrometer level accuracy, so don't want too much Z axis (horizontal) displacement which would push LDS out of range.
May i suggest that you think about music wire around 0.030" diameter. You would want to preload (stretch) it so that the lower section never comes out of tension at your expected payload. I did not do the math but it might be in the range of 0.020 inches of stretch. The wire should hold 75 lbs in tension overall.
Just ebay piano wire. We bought ours there. -
#1481 by otlski on 22 Apr, 2016 01:12
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Thank you. I've looked around for this type of wire, if you see something, I'd appreciate a link. So many welding wires to sort through.
McMaster Carr (of course)
http://www.mcmaster.com/#music-wire/=1232jip
The 1080 is the cheapest although weird that it is over 260,000 psi. Based on that you step down in diameter. -
#1482 by docmordrid on 22 Apr, 2016 01:36
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#1483 by spupeng7 on 22 Apr, 2016 01:37
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I'm not a physicist, so please forgive me if this question proceeds from a basic misunderstanding. A couple of years ago I remember reading a couple of articles that hinted at a distinction between gravitational and intertial mass. The Technology Review article refers to intertial mass of the photons involved in Unruh radiation. Is there a relation between the distinction between gravitational and inertial mass, and the proposed mechanism by which the EM drive produces thrust?
coypu76,
IF... gravity and inertia are electromagnetic effects, which many physicists have it in mind to prove, then the mechanism of action of the emdrive will be easier to comprehend. The unification of gravity with electromagnetism presents problems for physics but engineers are bound only by the practical. If the emdrive continues to be validated as a free space drive system then physics is going to undergo a revolution of some sort.
My personal opinion is that complex time is yet poorly understood and a more rigorous incorporation of the reality of complex time into our concepts of gravity and inertia may one day prove useful.
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#1484 by Eusa on 22 Apr, 2016 02:56
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My vacuum quanta interpretation of the general relativity theory is based on standing (generally spherical) gravity waves surrounding the gravitating body comoving with it. That is a proposal for the curvature of spacetime mechanism. The standing gravitational wave guides inertons (or gravitons, the same thing) to turn their flow towards the body so that its mass energy can be supported as inertial in space.
If we can make the flow of inertons (the quanta of the vacuum) to thicken artificially, it is the same we make artificial mass. It may be possible that em waves has the the same substructure as gravity waves but electric component should be handled.
There is so an explanation that em-drive and my proposed more effective g-drive could accelerate because of the artificial mass concentrate that attract all massive bodies and the chamber is the nearest object!
To be compatible with GR my inertons must be non-inertial energy packets propagating at causal speed c. So the aether of space would be dynamic background always at the speed of light in relation to inertial things.
If there is the probe flying by a planet so that its little more massive parts are not at the inner peripheral, the length contraction due the velocity in relation to penetration of inertons may affect the "extra" acceleration.
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#1485 by Gordon Powell on 22 Apr, 2016 03:39
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Comments on fabricating a Shawyer emdrive cone:
Silver soldering is a dandy way to join copper. I have found that silver soldering goes easier if silver is first friction rubbed on the the joined surfaces. I just use silver wire and rub it.
A future and possibly better way to fabricate a Shawyer cone would be to make the frustrum first out of fused quartz. Then vacuum evaporate a silver deposit. Then use either electrolytic deposition or chemical electroless deposition to make the deposit thicker. No joining is needed and, further, the fused quartz should make a dandy high Q dielectric. -
#1486 by zen-in on 22 Apr, 2016 06:11
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Comments on fabricating a Shawyer emdrive cone:
Silver soldering is a dandy way to join copper. I have found that silver soldering goes easier if silver is first friction rubbed on the the joined surfaces. I just use silver wire and rub it.
A future and possibly better way to fabricate a Shawyer cone would be to make the frustrum first out of fused quartz. Then vacuum evaporate a silver deposit. Then use either electrolytic deposition or chemical electroless deposition to make the deposit thicker. No joining is needed and, further, the fused quartz should make a dandy high Q dielectric.
Do you mean the Silver solder used in jewelry fabrication or the low temp electrical solder that is labeled Silver Solder? The Silver solder Silversmiths and jewellers use has melting points from 1190 F (643 C) - 1490 F (810 C). There are also "Silver" solders sold for Aluminum, Copper, Brass and other metals. Some don't have any Silver in them. The high temperature Silver solders produce a weld that can be stronger than the metal being joined. However the high temperatures required to make the solder flow will cause a lot of oxidation - black flaking CuO - of the Copper and will soften it, possibly making it warp and change shape. The only advantage to using any Silver solder for a fustrum, compared to ordinary lead-tin solder is more strength in the weld. The Silver alloy used has high electrical resistance; unlike pure Silver. -
#1487 by Flyby on 22 Apr, 2016 07:44
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Well, i didn't want to start any polemic about it, because I value the high level discussions too much to let the topic sidetracked by such a trivial discussion about a poll. Hence why i waited so long to say anything about it...About that poll...
OK, message received, thought it would be an interesting conversation starter, but not in a negative sense. For those of us who are not in the peer-review world, the whole process seemed secretive and black-magic...picking your peer review team, not picking your team, where to publish, what to publish, when to time it, how many revisions do you have to write, when is enough enough, etc.
In all honesty...and without any blunt intend ( my apologies if someone is unintentionally offended)... but....
I cant find the point nor the "fun" in having such a poll
The only word that spontaneously pops up in my mind is..."annoying" ...sorry...
Poll will close.
p.s. I've always been very open to respectful suggestions, even when they run contrary to my own way of thinking. This being the primary reason I've hung around this forum for a while and permanently left others.
However, I do understand why you did it: it was at a time there was some noticeable slowdown in discussion pace. Maybe it wasn't just the right tool or question to spark some life in the discussion?
but please, let's turn the page and continue with the real interesting discussions...
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#1488 by Rodal on 22 Apr, 2016 12:52
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Intrigued by your posts about that forum, in which I have never posted, I spent time to look for myself and I found (*) a remarkable high-quality post there (author: iorgfeflkd), under their PHYSICS thread, not the EM Drive thread, that makes a number of good technical points regarding McCulloch's theory.
The latter is not worth linking to IMHO. Those of us with first-hand experience communicating with the anonymous posters there found they're mostly off-topic, unsubstantiated opinions from dubious individuals, some claiming credentials they do not posses. That's a mouth-full for basically a lack of professional communications skills.
Always good to give our kind readership any links to rebuttals, etc.,Houston Examiner 4/20/16 on-line article:
http://www.examiner.com/article/has-the-impossible-em-drive-being-tested-by-nasa-finally-been-explained
IBT 4/21/16 on-line article:
http://tinyurl.com/j4jkfmq
Just propagating incorrect conclusions it seems going from the criticism I've seen online of the original article.
I am going off the comments under the original article & on the EM Reddit.
p.s. Quoting one of their more prolific users today "You're a charlatan, a dedicated crackpot, or both." I think this gives you the general idea on the level of discourse there...and it is permitted.
Anybody interested in the EM Drive and attracted by this theory should address these points:Quote from: iorgfeflkdThe suspicion begins on the first equation when they define conservation of momentum for a photon using the Newtonian formulation, which is not at all appropriate because it's classical, non-relativistic, and depends on mass. For the photon mass they invoke "MiHsC" which means "Modified Inertia due to a Hubble-scale Casimir effect," except it's not due to Hubble-scale confinement in this case, it's due to the walls of the cavity...ok fine...just say "the photon gains an effective mass due to confinement in the cavity." Anyway, they claim an accelerating object gains a proportional increase in mass due to the Unruh effect and also a cosmological factor. Ok, but the photon has zero mass anyway so this won't increase it, according to his own equation.
QuoteThis is possible because the photons involved are travelling at the speed of light and are bouncing very fast between the two ends of seperation s and their acceleration (a ∼ v^2 /s) is so large that the Unruh waves that are assumed to produce their inertial mass are about the same size as the cavity, so they can be affected by it, unlike the Unruh waves for a terrestrial acceleration which would be far to long to be affected by the cavity
Ok, what? I guess it's some sort of effective "expectation" acceleration for light in the cavity...plugging in some values we get about 1017 m/s^2 for acceleration and applying Wien's law to the Unruh temperature (is that what they're saying?) gives a peak wavelength of 1.5 meters. Ok, 10 times the size of the cavity...where does the inertial mass come from? This is not made clear. Nowhere in this derivation does it say where the inertial mass comes from for the photons, and then it continues to use this mass in the rest of its derivations so I can't really follow it. He uses the relation E=mc^2 to get rid of the photon mass (again, this does not apply to photons) and handwaves this energy into the time-integrated power. Comparing his equation 9 with his equation 7, he is claiming that photons in this cavity have a rest mass of 832 times that of a proton. Experimental bounds on photon mass are thirty orders of magnitude smaller. I thiiiiink that's where he's getting this force from. This also predicts the photons are propagating at roughly 1 m/s. A rough calculation puts the excess mass due to all these photons at about .4 grams, which is proportional to the square of power. Because the force is linear with power, and the excess mass due to photons increases with the square of power, this predicts that acceleration will actually decrease with enough power
In my opinion if they are going to invoke the Unruh effect which comes from quantum field theory, they should work in a formalism that is consistent with quantum field theory and not use Newtonian mechanics with combined massive/massless particles.
The final result is that they derive a force/power ratio for the system of 216 millinewtons/kilowatt (4.6 km/s). If we compare this to what is expected from radiation pressure, which actually exists, that is just the speed of light so 0.003 mN/kW.
tl;dr [too long; didn’t read] the photon gains mass proportional to the microwave power in the cavity, and then gains more mass due to the Unruh radiation from accelerating between the cavity walls.
Why did I spend so much time on this.
edit: I was out for a jog and realized another crucial flaw: it invokes the Unruh effect to explain why the "cone-ness" causes thrust. It uses the acceleration c^2 / d to get the Unruh radiation. However, the photon mass imposed by the cavity (which is a different effect, in this paper) reduces the velocity to 1 m/s, bringing the acceleration down by a factor of 9x10^16 . I think if this were to be propagated through, it would bring the expected force down by the same amount.
It is an excellent post, because rather than make vague qualitative remarks, it actually does what physicists and engineers do: it calculates, using numbers, to ascertain the validity of what is being proposed.
There are a number of important points here questioning the theory (importantly, for example that the rest mass of the photons inside the cavity would exceed by orders of magnitude the rest mass of a proton).
On the other hand, the following pointQuoteBecause the force is linear with power, and the excess mass due to photons increases with the square of power, this predicts that acceleration will actually decrease with enough power
is a very interesting possible way out of the energy paradox (as the acceleration will actually decrease with enough input power): recall that because according to these EM Drive theories (Shawyer and McCulloch) the force is proportional to the input power, and this exceeds by orders of magnitude the force/PowerInput of a photon rocket, eventually (at high enough speed) the kinetic energy exceeds the input energy. However, since according to McCulloch's theory the excess mass of the photon increases with the square of the power, the acceleration will reach a plateau and will actually eventually decrease, and so will the increase in speed and hence the kinetic energy may be limited, posing the question whether energy, after all, may be conserved under the assumptions of McCulloch's theory.
Has this way out of the energy paradox been previously explored?
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(*) Hat tip to NSF member WhatAFeynDay -
#1489 by rfmwguy on 22 Apr, 2016 13:30
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Looks like you found a good thread on the forum site. My only experience was on the emdrive thread and that was terrible. The physics thread is new to me. That physics thread poster does bring up some good thoughts. My theory-lite version is the arguments tends to revolve around photons and unruh radiation effects which still have yet to be properly sorted out. Unconventional theories is what discovery is all about and why I love hanging around this site..."what-ifs" are nothing to be intimidated about.
Just like DaCunha's new thread: http://forum.nasaspaceflight.com/index.php?topic=40071.0
Fascinating (raised eyebrow) -
#1490 by rfmwguy on 22 Apr, 2016 14:04
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Forbes 4/21/16 article: "The Theoretical Model For This Impossible Space Drive Doesn't Prove Anything"
http://tinyurl.com/gn86r85 -
#1491 by Rodal on 22 Apr, 2016 14:06
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Looks like you found a good thread on the forum site. My only experience was on the emdrive thread and that was terrible. The physics thread is new to me. That physics thread poster does bring up some good thoughts. My theory-lite version is the arguments tends to revolve around photons and unruh radiation effects which still have yet to be properly sorted out. Unconventional theories is what discovery is all about and why I love hanging around this site..."what-ifs" are nothing to be intimidated about.
The moderators preface that antecedes the post by iorgfeflkd in the Physics thread actually confirms your remarks:
Just like DaCunha's new thread: http://forum.nasaspaceflight.com/index.php?topic=40071.0
Fascinating (raised eyebrow)Quote from: CarbonRodOfPhysicsEM-drive posts have been filled with a great deal of off-topic content, often ad hominem attacks between redditors and other drama. This thread will be heavily moderated.
If you have a comment regarding the physics in the linked paper, it is welcome. Other comments will probably not show up.
notice that the Physics thread moderators at that forum exercised "heavy editing" of ad hominem attacks and off-topic content, and that the high-quality quoted post by iorgfeflkd emerged within the context of that heavy moderation. -
#1492 by RotoSequence on 22 Apr, 2016 14:14
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Forbes 4/21/16 article: "The Theoretical Model For This Impossible Space Drive Doesn't Prove Anything"
http://tinyurl.com/gn86r85
Well, the headline isn't wrong. The text of the article is actually a pretty good summary, too. -
#1493 by Rodal on 22 Apr, 2016 14:19
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Forbes 4/21/16 article: "The Theoretical Model For This Impossible Space Drive Doesn't Prove Anything"
The author is a Senior Lecturer at Rochester Institute of Technology with degrees in Physics from Southern Illinois University (B.S.), and The University of Connecticut (Ph.D.). He is also the author of the Cambridge University Press book "Astrophysics through Computation: With Mathematica® Support" using the same mathematical code (Wolfram Mathematica ®) to perform Astrophysical calculations I used to write computer programs to calculate the Stress tensor field components and Poynting vector fields in the EM Drive as well as to post in this EM Drive threads exact solution results that compared excellently with NASA's COMSOL Finite Element Analysis of their experimental mode shapes.
http://tinyurl.com/gn86r85 -
#1494 by rfmwguy on 22 Apr, 2016 14:34
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just did a quick glance, but did not find a compelling argument against mccullough's theory itself...seemed like more of an op-ed pieceForbes 4/21/16 article: "The Theoretical Model For This Impossible Space Drive Doesn't Prove Anything"
The author is a Senior Lecturer at Rochester Institute of Technology with degrees in Physics from Southern Illinois University (B.S.), and The University of Connecticut (Ph.D.).
http://tinyurl.com/gn86r85 -
#1495 by RotoSequence on 22 Apr, 2016 14:39
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just did a quick glance, but did not find a compelling argument against mccullough's theory itself...seemed like more of an op-ed piece
I didn't get the impression that he was writing for, or against McCulloch's theory as much as he (rightly) pointed out that there's a lot of unproven and untested hypothesis involved when one uses MIHSC to explain EM Drive. As it is, MIHSC offers an incomplete theoretical explanation for EM drive, which currently does not take resonance into account. -
#1496 by rfmwguy on 22 Apr, 2016 14:41
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If I use the tactics of those not convinced of the emdrive effect, I'd say this author's post lacks the math to make a convincing argument that mccullough's theory paper is incorrect. Rodal is right, there are better reads on the physics thread of the other forum.Forbes 4/21/16 article: "The Theoretical Model For This Impossible Space Drive Doesn't Prove Anything"
http://tinyurl.com/gn86r85
Well, the headline isn't wrong. The text of the article is actually a pretty good summary, too. -
#1497 by rfmwguy on 22 Apr, 2016 14:44
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Yay! Goes to show the other forum's topics are only as good as the mods. The overall owner of the site could not possibly handle the 1000s+ of threads themselves and leave it to volunteers. Glad someone there wised up. Good for CarbonRodOfPhysicsLooks like you found a good thread on the forum site. My only experience was on the emdrive thread and that was terrible. The physics thread is new to me. That physics thread poster does bring up some good thoughts. My theory-lite version is the arguments tends to revolve around photons and unruh radiation effects which still have yet to be properly sorted out. Unconventional theories is what discovery is all about and why I love hanging around this site..."what-ifs" are nothing to be intimidated about.
The moderators preface that antecedes the post by iorgfeflkd in the Physics thread actually confirms your remarks:
Just like DaCunha's new thread: http://forum.nasaspaceflight.com/index.php?topic=40071.0
Fascinating (raised eyebrow)Quote from: CarbonRodOfPhysicsEM-drive posts have been filled with a great deal of off-topic content, often ad hominem attacks between redditors and other drama. This thread will be heavily moderated.
If you have a comment regarding the physics in the linked paper, it is welcome. Other comments will probably not show up.
notice that the Physics thread moderators at that forum exercised "heavy editing" of ad hominem attacks and off-topic content, and that the high-quality quoted post by iorgfeflkd emerged within the context of that heavy moderation. -
#1498 by Tellmeagain on 22 Apr, 2016 15:03
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I didn't get the impression that he was writing for, or against McCulloch's theory as much as he (rightly) pointed out that there's a lot of unproven and untested hypothesis involved when one uses MIHSC to explain EM Drive. As it is, MIHSC offers an incomplete theoretical explanation for EM drive, which currently does not take resonance into account.
Am I the only one who think that MiHsC is a badly chosen name? It is neither easy to remember, nor easy to pronounce. -
#1499 by Dortex on 22 Apr, 2016 17:51
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is a very interesting possible way out of the energy paradox (as the acceleration will actually decrease with enough input power): recall that because according to these EM Drive theories (Shawyer and McCulloch) the force is proportional to the input power, and this exceeds by orders of magnitude the force/PowerInput of a photon rocket, eventually (at high enough speed) the kinetic energy exceeds the input energy. However, since according to McCulloch's theory the excess mass of the photon increases with the square of the power, the acceleration will reach a plateau and will actually eventually decrease, and so will the increase in speed and hence the kinetic energy may be limited, posing the question whether energy, after all, may be conserved under the assumptions of McCulloch's theory.
Has this way out of the energy paradox been previously explored?
I'm not understanding the reasoning. Relativity is still a thing. Hell, we went ahead and confirmed it yet again with advanced LIGO. Why would speed, or velocity, or really anything to do with kinetic energy, stop a drive from accelerating? It's always standing still from the perspective of the ship. This is not, as I understand it, some funny way of looking at things. It's literally true and just as valid as any other observer's perspective.
