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#1040 by wicoe on 27 Sep, 2016 04:59
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Consider a hypothetical rocket that can do 10000 burns at a delta v of 1000 m/s. Each burn requires a total energy of E, maybe only 1% goes to the ship. After the first burn, the kinetic energy of the ship wrt earth is 5E5/kg so assume the burn released 5E7 J/kg in its frame. What's the total energy released in the ships frame after 10000 burns? It should be 5E10J/kg. What's the kinetic energy wrt earth? It should be 5E13J/kg. No doubt some will claim nature conspires to prevent this by making the mass requirements great enough so it's never practical to make such a rocket.
It's not about "nature conspiring to prevent this", it's about math... assuming that CoE holds. One has to take into account not just the kinetic energy of the rocket, but also the kinetic energy of the propellant (which decreases since it's being ejected in the opposite direction if you compare it to an earlier moment when it was moving together with the rocket). The rocket has to be constantly losing mass (i.e. propellant), and if you calculate the total energy over time, it all adds up and no "over-unity" occurs. The rocket does not know when to stop accelerating, it slows down naturally because it's losing mass/propellant. If there is no propellant and the rocket is not losing mass, "over-unity" is an obvious consequence, unless there is a way for it to "steal" energy from some unknown field. -
#1041 by Bob Woods on 27 Sep, 2016 05:10
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[r they could be machined from large solid blocks of almost anything. Almost anything can be coated with almost anything. Copper on baby shoes, nickel on wood, gold on plastic, plutonium on niobium...there are companies that do this stuff all the time. Just saying.
Dissimilar metals in contact with each other are subject to chemical reactions. The most obvious conductors are a result of various aqueous solutions. I know, because I have a metallic hip replacement where the interaction between a titanium stub coupled with a chromium/cobalt stem has been releasing elemental cobalt and chromium into my body to the detriment of nerve fibers.
I don't know if anyone has ever studied what interactions might occur in the presence of high-level microwave radiation and the associated heat might induce. Someone might want to investigate that. -
#1042 by Star One on 27 Sep, 2016 05:57
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With that warning, I was actually not referring to you, Shell or Mono. As engineers, you all know your stuff, that's obvious.
Didn't think that at all. At one time I thought NSF would be a great place for DIY tips, techniques but decided to back off of that philosophy. However, your inputs are still in that spirit and am glad to see it.
But when the EagleWorks review hits the street, I fear a lot more hobbyists with 3Dprinting dreams will have a go at building their own version of the EMdrive. Hence the warning .... maybe I should have said "to all future DIY's..."
It certainly was not the intention of belittling any of the current DIY builders.
My apology if it was perceived in such way...
My guess is the world will soon see a rash of prospective EmDrive builders. Guidance, especially towards safety is needed. Active posters can pick up that banner if they wish. Back to inactive for me...I've had my fill for a while - Cheers, Dave
As long as it doesn't see a rash of ill prepared people injuring themselves playing around with microwaves. -
#1043 by Acryte on 27 Sep, 2016 06:12
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No, you don't get massive 'free' energy. What you get is different energies in different reference frames. You can see that simply by the following example. Say a ship is moving wrt earth frame at just under 0.5c by 1000m/s and you observe it. The ship makes a burn to increase its velocity wrt you by 1000m/s to exactly 0.5c wrt you. For a 10,000kg ship, how much energy does the pilot need to add? It depends on which reference frame. In the ships frame the pilot only needs to do the same burn to gain 1000m/s as always which is 5E9 J. You would say its about 1.5E15 J. It does gain that but not by the ship expending that energy in its reference frame. It would be the same regardless of a rocket of an EmDrive engine except the EmDrive would be more efficient. No doubt some will claim the rocket fuel already has kinetic energy, which it does, but that's natures gift, not something the ship had to provide by internal energy release stored as fuel because it never had that energy content to begin with. If someone objects further then consider that the ship was launched from a planet already moving at just under 05c to start with.
The bottom line is that the actual energy to get to the stars is probably a lot less that convention dictates.
P.S. I understand Woodward and allies previously released an essay demolishing the free energy or over unity arguments.
http://ssi.org/epi/Over-Unity_Argument_&_Mach_Effect_Thrusters.pdf
Was that discussed at the workshop?
Correct.
In the ship's frame, the only one which matters, the energy needed to alter velocity in relation to some desired destination is always the same as the ship's mass does not alter. Well not so much as it matters.
BTW Jim Woodward makes a good comment:
http://ssi.org/epi/Over-Unity_Argument_&_Mach_Effect_Thrusters.pdfQuoteWe routinely hear a criticism of METs based upon an argument that claims: if a
MET is operated at constant power input for a sufficiently long time, it will acquire
enough kinetic energy to exceed the total input energy of operation. Assuming this
argument to be correct, critcs assert that METs violate energy conservation as the ratio of
the acquired kinetic energy to total input energy exceeds “unity.”
Contrary to this “over-unity” assumption, this argument is based on flawed
physics and, consequently, wrong. The fact that the argument applies to all simple
mechanical systems (in addition to METs) should have alerted critics to their mistake.
But it didn’t.
So, a dumb idea that should have been quickly buried is still with us. The
purpose of this essay is to carry out a long overdue burial.
Interesting paper. I glanced at it and found the math was within my ability. So I printed it out to take a closer look. I think I will be able to find something wrong in his argument. But I may not be able to. Whatever the result is, I will write a swift report about my findings.
As promised, I wrote a short report. The attached picture is a screen short of the first page of the report. The whole report is also attached to this email. As meberbs, I now think Professor Woodward does not have credit in his theory.
Edit: Updated report because originally on page 3 I used M for both mass and for mega (10^6), thus may cause confusion. I updated the report so that now M is only for mass.
Nice paper. I couldn't help but laugh however when I came across: "the ejected propellant mush". -
#1044 by zen-in on 27 Sep, 2016 06:13
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...
a) Lost wax 3dprinting
As the name indicates, it involves a secondary process of metal melting and needs a metal foundry set up.
Such a casted piece would need additional machining to obtain a high reflective surface.
...
This has been discussed before. Copper has to be cast in a vacuum. Fine Silver (999) is relatively easy to cast but the walls would have to be quite thick. Otherwise there would be voids. Another problem with the lost wax process is it is not practical to cast a hollow container where the interior plaster mold is not supported at all. I think the most practical method of building a Copper or Fine Silver fustrum is to spin-form it on a lathe. Second to that would be to roll out a cone pattern and join the two sides with a riveted strip, using Copper rivets. That will ensure electrical continuity at the seam. The end caps can also be screwed together, using Copper screws. A while back someone was in touch with a Copper cookware manufacturer who could do this type of work. It requires specialized tools to get a finished article with smooth surfaces. -
#1045 by birchoff on 27 Sep, 2016 07:11
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....
As promised, I wrote a short report. The attached picture is a screen short of the first page of the report. The whole report is also attached to this email. As meberbs, I now think Professor Woodward does not have credit in his theory.
Edit: Updated report because originally on page 3 I used M for both mass and for mega (10^6), thus may cause confusion. I updated the report so that now M is only for mass.
Ok, I have some questions about this report. First off I mostly agree with the last section of it. However, Part II through III are problematic. Specifically, after reading your Part II and re reading the section in the Woodward Paper I believe you are both either talking past each other or saying the same thing. As you said in the section your referencing he is describing the behavior of a Simple Mechanical system. The difference is that at the end of that section in woodward's Paper the point he was trying to make wasQuote...
How then do some argue that in this simple system – and METs in particular – energy conservation is violated?
Simple. By doing something stupid and wrong. In particular, by taking the “figure of merit” of a thrust (force) generator – by definition, the number of Newtons of thrust produced per watt of input power to the thrust generator – and treating it as a dynamical equation that can be used to calculate the energy input to a motor that acts for
some length of time; that is:
...
which seems to be the same thing your saying hereQuote...
Now take a look of his equation (10). By defining a constant figure of merit, he explicitly made P = FmF constant. This directly contradicts to the fact P = F at. No wonder he reached contradiction as shown by his equation
(15).
Who proposed “figure of merit”? It might be Mr. Shawyer, who invented that for his propellant-less EmDrive, similar to the MET in propellant-less sense. the critics’ logic is that since Mr. Shawyer’s figure of merit leads to contradiction, his theory is wrong. So does MET if it has constant force with constant power. The simple mechanical systems as shown in Professor Woodward’s equation (1) through (9) is compatible with CoE ...
...
The only issue I have with your version of the statement is it seems like you are attributing how the figure of merit equation is used to Woodward. When really all Woodward is doing is illustrating why you should not define/use the figre of merit equation in the manner you both described.
As forQuoteThe simple mechanical systems as shown in Professor Woodward’s equation (1) through (9) is compatible with CoE, but EmDrive and MET are not.
I think this gets as closer to the true problem with this paper than the rest of what is included in the report. Which is that entire section you refer to in part II of your report is only talkiing about Simple mechanical systems. Nothing else. HE does occasionally mention MET's but only as an example of a Simple Mechanical system. Which brings me to my point. The main criticism that should be leveled at this Paper is that it asks the reader to accept a pretty big assumption and proceeds from that point forward. That assumption isQuoteContrary to this “over-unity” assumption, this argument is based on flawed physics and, consequently, wrong. The fact that the argument applies to all simple mechanical systems (in addition to METs) should have alerted critics to their mistake. But it didn’t. So, a dumb idea that should have been quickly buried is still with us. The purpose of this essay is to carry out a long overdue burial.
That underlined portion basically asks you to assume that a MET is a simple mechanical system. Now whether or not your accept this to be true I think depends on whether or not you understand and agree with of all the work Woodward, Fearn, and Wasner have put into explaining his theory behind how a MET works. There is nothing in the Paper that covers how a MET works at all. Instead, Woodward assumes, for the sake of the paper, that a MET is a Simple Mechanical device and proceeds to refute the idea that Simple Mechanical Devices can create over unity.
As for Part III. The reason equation (16) is included is stated pretty clearly in the paragraph immediately before the equation is stated. With its purpose being to guide a discussion about how to correctly calculate momentum conservation for a rocket. Which it looks like you replicated also. The only difference is Woodward spends a few sentences talking about the difference between the force represented by v dM/dt and the force represented by Ma. This particular exposition seems superfluous but when a device governed by ME is operating it is claimed that the v dM/dt term in that equation can be taken to be zero. It is the reason why he uses this exampleQuoteA pile of sand on the bed of the car is allowed to fall through a hole in the floor of the car. Does the speed of the car relative to the Earth (which can be taken to have effectively infinite mass) change as the sand falls?
That pile of sand is meant to represent the fluctuating mass in a device governed by ME. Now I have had a spirited discussion with WallOfWolfStreet about this and as far as I can tell at this point in time you either agree that the Mass Fluctuations that take place within the Fluctuating Mass component of a device governed by ME happen exactly in the way necessary to allow the v dM/dt force term to be set to 0 or you need to spend some time digging into the GR Derivation of Mach Effects and or the Hoyle Narliakr Theory of Gravitation. Personally, that stuff is a bit above my pay grade currently so I will settle for experimental results agreeing with the thrust values predicted by the thrust equations derived from both the GR and HN Theory; oh yeah and replications of said experimental results.
Finally, Part III. I agree with the motivation of Part III but that's only because the paper does what I consider a piss poor job of actually talking about how a MET is supposed to work. It pretty much assumes the reader does. After doing some digging of my own I actually wonder if the reason the explanation at the end of Woodwards Paper could be valid is because a device governed by ME from a mechanical perspective has the ability to control/oscillate the Mass of one of its components, which is constantly being accelerated and decelerated repeatedly. To avoid me rehashing my thoughts on this please see
http://forum.nasaspaceflight.com/index.php?topic=40959.msg1588451#msg1588451 -
#1046 by Stan-1967 on 27 Sep, 2016 07:22
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...
a) Lost wax 3dprinting
As the name indicates, it involves a secondary process of metal melting and needs a metal foundry set up.
Such a casted piece would need additional machining to obtain a high reflective surface.
...
This has been discussed before. Copper has to be cast in a vacuum. Fine Silver (999) is relatively easy to cast but the walls would have to be quite thick. Otherwise there would be voids. Another problem with the lost wax process is it is not practical to cast a hollow container where the interior plaster mold is not supported at all. I think the most practical method of building a Copper or Fine Silver fustrum is to spin-form it on a lathe. Second to that would be to roll out a cone pattern and join the two sides with a riveted strip, using Copper rivets. That will ensure electrical continuity at the seam. The end caps can also be screwed together, using Copper screws. A while back someone was in touch with a Copper cookware manufacturer who could do this type of work. It requires specialized tools to get a finished article with smooth surfaces.
This is my first post in the EM drive section. This post is for those looking to make an EM drive themselves.
I'm a DIY'er who works with electroplating materials for a living, and from what I am reading going back to post 1005, there are quite a few methods being considered here for how to make the frustum and endplates. Maybe I missed it, but are there any specifications that are agreed upon for what the end product ( EM Drive cavity) needs to meet?
1. What material properties are needed on the surface vs. the bulk of the EM drive?
2. Inner & outer surface smoothness ( RA)?
3. Frustum & endplate wall thickness?
4. Tolerance for oxidation/sulfidation anywhere on the EM drive?
5. Electrical continuity of the joints of the endplate, & possibly frustum sections if making them in sections?
6. Tolerance for imperfection in the conical section of the frustum? how much can it vary and still get consistent resonance?
Since the first pics of the EM drive were shown, I've thought of ways to make it using methods I see in the metal finishing industries I am familiar with. Most of what I have seen in the RF industry was done by making mandrels from machined aluminum, which was then electroplated.
The 3-D printed wax methods also have some promise, however metallizing those substrates to the thickness specs. being mentioned is going to be expensive and difficult. Casting may also be a valid path.
Has anyone considered CNC metal spinning? This may be ideally suited for making the EM drive frustum and endplates. Copper can also be spun with this method, negating the need to electroform thick walls. CNC Metal spinning should allow a very repeatable & standardized frustum & endplates to be made. These parts will be pretty close to a finished form. If needed, they could be put on a lathe to smooth out the inner surface of the frustum. Once that is done, there are common electroplated materials that can tailor the surface properties. You can then selectively deposit resistive coating like Ni-W, or very smooth & low resistance Cu-Ni-Au. I would also attach the endplates to the frustum by electroplating a tin or tin alloy solder onto the joining surfaces, and reflow it in an oven vs using bolts.
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#1047 by Gilbertdrive on 27 Sep, 2016 09:11
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Consider a hypothetical rocket that can do 10000 burns at a delta v of 1000 m/s. Each burn requires a total energy of E, maybe only 1% goes to the ship. After the first burn, the kinetic energy of the ship wrt earth is 5E5/kg so assume the burn released 5E7 J/kg in its frame. What's the total energy released in the ships frame after 10000 burns? It should be 5E10J/kg. What's the kinetic energy wrt earth? It should be 5E13J/kg. No doubt some will claim nature conspires to prevent this by making the mass requirements great enough so it's never practical to make such a rocket.
In fact, there is no need to use directly the CoE principle. The newtonian mechanics complies with CoE. So we can solve this problem by using Newtonian mechanics, and the result will always respect CoE. The fact that it is not pratical to do the rocket is not a theoretical problem. Since newtonian mechanics are consistent with CoE, we can not even find a theoretical counter example.
So, I propose to analyse your example, and detail why it does not work.
First, it is true that the same burn will give the same acceleration relatively to different inertial reference frames if we are in Newtonian Mechanic (not relativist effect). But that needs of course to have ships of the same mass. So, it was right to use this principle same burn/same acceleration for 2 identical ships going at different speeds from earth, but you can not use it for comparing 2 successive burns of the same ship. The second burn give more acceleration that the first one, since the ship is lighter. At the same time, when the ship is lighter, for the same speed, it's Kinetic energy is lower.
First, if each burn realeased 5E7 J/kg, the total energy released would be 5E7*E4=5E11, not 5E10.
I perfectly understand your analysis, and your assertion. But you have taken impossible data. The impossible data is… the fact that 1% of the Energy was given to the ship, while 10 000 burns are possible.
If 10 000 burns are possible, each burn uses less than the mass of the ship divided by 10 000.
I shall suppose that the first burn has a perfect efficiency. It means that all the energy spent goes in motion, not in heat.
I shall suppose that the mass ejected during the burn is the mass of the ship divided by 10 000, forgive me, only 9 999 burns are possible, and I shall suppose that the mass of the empty ship itself is 1/10 000. after the first burn, assuming it is a instantaneous burn, like if the ship shot a bullet, the speed of the ejected mass will be of 999,9m/s and the speed of the ship will be 0,1m/s in the earth referential.
I call mb the mass ejected during a burn
It means that the Kinetic Energy of the ship will be Ks=½*mb*9999*(0,1)^2 when the Kinetic Energy of the expulsed mass will be Ke=½*mb*(999,9)^2
I calculate the ratio Ks/Ke=(9999*(0,1)^2)/(999,9)^2=0.00010001
It is around 10^-4
That means that only a little more than 0,01% of the spent energy goes to the Kinetic Energy of the ship. Most of the Energy goes to the expulsed mass.
That is why expulsing few mass at high speed is not energy efficient. That is why even a perfect ionic motors would not be great for pushing a car. That is also why the amelioration of ionic needs more and more energy. If we send the ions 10 times faster, we get 10 times more acceleration for the ship, but it needs 100 times more energy. So, the same acceleration needs 10 times more energy !
The lighter the ship is, the more efficient will be the burn. The 9999th burn will expell as much mass that the remaining mass on the ship, and the half of the Energy spend goes to the Kinetic Energy of the ship, but the ship is loosing at the same time half of it's mass, so it divided by 2 the Kinetic Energy of the ship.
At the end, the Ship will have a very few Kinetic Energy. Most of Kinetic Energy will belong to the expulsed propellant.
I can detail more, and make the calculus of how much Kinetic energy the ship has at the end, but for that, you need to detail your ship.
-mass of the ship
-mass ejected for each burn
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#1048 by Gilbertdrive on 27 Sep, 2016 09:30
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The statement "Since the 10 years of operation of the 200Kwe generator gives only 6.311*10^13 Joules" is in the ships frame or really, frames. If you claim it's also in the observer frame you are ignoring the multiplicative factor that converts between frames.
It is in the ship frame. I did not made the calculus of how much time was elapsed in the Earth frame. Anyway it will not change the magnitude of the problem : around 10^7. More than 10 years will have occured on earth, but not 100 million years.
If the over unity compliant is correct, Shawyer's probe should run into that condition in under 7 seconds from launch. The Cannae Probe would end at 267 seconds. So, easy to tell.
Easy to tell...if these probes were constructed, yes
But they exist only on paper for now. -
#1049 by Tellmeagain on 27 Sep, 2016 11:29
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Thank you！ I will try to answer your concerns.
....
As promised, I wrote a short report. The attached picture is a screen short of the first page of the report. The whole report is also attached to this email. As meberbs, I now think Professor Woodward does not have credit in his theory.
Edit: Updated report because originally on page 3 I used M for both mass and for mega (10^6), thus may cause confusion. I updated the report so that now M is only for mass.
Ok, I have some questions about this report. First off I mostly agree with the last section of it. However, Part II through III are problematic. Specifically, after reading your Part II and re reading the section in the Woodward Paper I believe you are both either talking past each other or saying the same thing. As you said in the section your referencing he is describing the behavior of a Simple Mechanical system. The difference is that at the end of that section in woodward's Paper the point he was trying to make was
Probably we were largely talking about the same thing in my Section II and his part 1. The difference might be that he contributed "figure of merit" to critics but I contributed it to Mr. Shawyer whose EmDrive shares largely the same features with his MET. Both being propellant-less. Both has limited input power but unlimited output power. The critics, by agreeing with my expressing of FS=1/2F*at^2, the energy generated by external force, agreed with physics; but Mr. Shawyer and Professor Woodward did not agree with physics by insisting limited input power and unlimited output power.QuoteQuote...
How then do some argue that in this simple system – and METs in particular – energy conservation is violated?
Simple. By doing something stupid and wrong. In particular, by taking the “figure of merit” of a thrust (force) generator – by definition, the number of Newtons of thrust produced per watt of input power to the thrust generator – and treating it as a dynamical equation that can be used to calculate the energy input to a motor that acts for
some length of time; that is:
...
which seems to be the same thing your saying here
Agreed. The difference is that he said the problem was caused by the critics by defining fixed input power; but I think it is his and Mr. Shawyer's problem.QuoteQuote...
Now take a look of his equation (10). By defining a constant figure of merit, he explicitly made P = FmF constant. This directly contradicts to the fact P = F at. No wonder he reached contradiction as shown by his equation
(15).
Who proposed “figure of merit”? It might be Mr. Shawyer, who invented that for his propellant-less EmDrive, similar to the MET in propellant-less sense. the critics’ logic is that since Mr. Shawyer’s figure of merit leads to contradiction, his theory is wrong. So does MET if it has constant force with constant power. The simple mechanical systems as shown in Professor Woodward’s equation (1) through (9) is compatible with CoE ...
...
The only issue I have with your version of the statement is it seems like you are attributing how the figure of merit equation is used to Woodward. When really all Woodward is doing is illustrating why you should not define/use the figre of merit equation in the manner you both described.
As forQuoteThe simple mechanical systems as shown in Professor Woodward’s equation (1) through (9) is compatible with CoE, but EmDrive and MET are not.
I think this gets as closer to the true problem with this paper than the rest of what is included in the report. Which is that entire section you refer to in part II of your report is only talkiing about Simple mechanical systems. Nothing else. HE does occasionally mention MET's but only as an example of a Simple Mechanical system. Which brings me to my point. The main criticism that should be leveled at this Paper is that it asks the reader to accept a pretty big assumption and proceeds from that point forward. That assumption isQuoteContrary to this “over-unity” assumption, this argument is based on flawed physics and, consequently, wrong. The fact that the argument applies to all simple mechanical systems (in addition to METs) should have alerted critics to their mistake. But it didn’t. So, a dumb idea that should have been quickly buried is still with us. The purpose of this essay is to carry out a long overdue burial.
That underlined portion basically asks you to assume that a MET is a simple mechanical system. Now whether or not your accept this to be true I think depends on whether or not you understand and agree with of all the work Woodward, Fearn, and Wasner have put into explaining his theory behind how a MET works. There is nothing in the Paper that covers how a MET works at all. Instead, Woodward assumes, for the sake of the paper, that a MET is a Simple Mechanical device and proceeds to refute the idea that Simple Mechanical Devices can create over unity.
He thought MET belongs to Simple Mechanical system but I think it is more close to the EmDrive, being with fixed force for fixed input power.Quote
As for Part III. The reason equation (16) is included is stated pretty clearly in the paragraph immediately before the equation is stated. With its purpose being to guide a discussion about how to correctly calculate momentum conservation for a rocket. Which it looks like you replicated also. The only difference is Woodward spends a few sentences talking about the difference between the force represented by v dM/dt and the force represented by Ma. This particular exposition seems superfluous but when a device governed by ME is operating it is claimed that the v dM/dt term in that equation can be taken to be zero. It is the reason why he uses this exampleQuoteA pile of sand on the bed of the car is allowed to fall through a hole in the floor of the car. Does the speed of the car relative to the Earth (which can be taken to have effectively infinite mass) change as the sand falls?
That pile of sand is meant to represent the fluctuating mass in a device governed by ME. Now I have had a spirited discussion with WallOfWolfStreet about this and as far as I can tell at this point in time you either agree that the Mass Fluctuations that take place within the Fluctuating Mass component of a device governed by ME happen exactly in the way necessary to allow the v dM/dt force term to be set to 0 or you need to spend some time digging into the GR Derivation of Mach Effects and or the Hoyle Narliakr Theory of Gravitation. Personally, that stuff is a bit above my pay grade currently so I will settle for experimental results agreeing with the thrust values predicted by the thrust equations derived from both the GR and HN Theory; oh yeah and replications of said experimental results.
The paragraph immediately before equation (16) ("I won’t attempt an answer to...") is one that I totally agree with. I think he talked about some general principles of mechanics and maybe unrelated to equation (16).
By using the sand car example, did he mean that his MET rocket can fluctuate its mass, just like by releasing an astronaut, and then taking him back in again? This is beyond my pay grade too.Quote
Finally, Part III. I agree with the motivation of Part III but that's only because the paper does what I consider a piss poor job of actually talking about how a MET is supposed to work. It pretty much assumes the reader does. After doing some digging of my own I actually wonder if the reason the explanation at the end of Woodwards Paper could be valid is because a device governed by ME from a mechanical perspective has the ability to control/oscillate the Mass of one of its components, which is constantly being accelerated and decelerated repeatedly. To avoid me rehashing my thoughts on this please see
http://forum.nasaspaceflight.com/index.php?topic=40959.msg1588451#msg1588451
Thanks for the link. -
#1050 by Gilbertdrive on 27 Sep, 2016 12:28
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True about Mr. Shawyer, but it depends where. In his theory paper 9.4 he clearly statues that the thrust is decreasing with the speed in the departure referential. But elsewhere, he forget that
Probably we were largely talking about the same thing in my Section II and his part 1. The difference might be that he contributed "figure of merit" to critics but I contributed it to Mr. Shawyer whose EmDrive shares largely the same features with his MET. Both being propellant-less. Both has limited input power but unlimited output power. The critics, by agreeing with my expressing of FS=1/2F*at^2, the energy generated by external force, agreed with physics; but Mr. Shawyer and Professor Woodward did not agree with physics by insisting limited input power and unlimited output power.
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#1051 by flux_capacitor on 27 Sep, 2016 13:11
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By using the sand car example, did he mean that his MET rocket can fluctuate its mass, just like by releasing an astronaut, and then taking him back in again? This is beyond my pay grade too.
That is indeed the whole point of Mach Effect Thrusters, or METs. According to Woodward's transient mass equation:
A mass fluctuation arises in an object when it absorbs energy (like a capacitor) as it undergoes proper acceleration. -
#1052 by Tellmeagain on 27 Sep, 2016 13:17
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By using the sand car example, did he mean that his MET rocket can fluctuate its mass, just like by releasing an astronaut, and then taking him back in again? This is beyond my pay grade too.
That is indeed the whole point of Mach Effect Thrusters, or METs. According to Woodward's transient mass equation:
A mass fluctuation arises in an object when it absorbs energy (like a capacitor) as it undergoes proper acceleration.
I agree that a capacitor can increase its mass by absorbing energy, because this is predicted by Einstein's mass-energy equation. However, the energy the capacitor absorbed is taken from the battery or other sorts of energy sources. By losing that same amount energy, assuming 100% efficiency, the battery's mass decreases with the same amount. If the battery is on board of the same rocket, how can that help? -
#1053 by jaydurst on 27 Sep, 2016 14:21
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The Mach Effect Thruster has always bothered me as the classical analogue clearly results in no thrust.
I can imagine something similar to a metronome fixed to a spaceship, with a sliding weight that moves up and down the pendulum depending on the direction of the swing. Obviously, this will always result in a net 0 movement in any direction for the spaceship. Acknowledging that electrons and the weight are different animals and my knowledge of physics at the level of the electron is laughably small, I can't see how it could possibly work. -
#1054 by birchoff on 27 Sep, 2016 14:24
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By using the sand car example, did he mean that his MET rocket can fluctuate its mass, just like by releasing an astronaut, and then taking him back in again? This is beyond my pay grade too.
That is indeed the whole point of Mach Effect Thrusters, or METs. According to Woodward's transient mass equation:
A mass fluctuation arises in an object when it absorbs energy (like a capacitor) as it undergoes proper acceleration.
I agree that a capacitor can increase its mass by absorbing energy, because this is predicted by Einstein's mass-energy equation. However, the energy the capacitor absorbed is taken from the battery or other sorts of energy sources. By losing that same amount energy, assuming 100% efficiency, the battery's mass decreases with the same amount. If the battery is on board of the same rocket, how can that help?
Because the mass fluctuation effect is not the same as a capacitor's mass changing on charging and discharging. If it was then Nembo Buldrini would not have recorded a null test result for the MET Woodward gave him to test in Tajmar's lab. If it was then the most recent experimental null results (Section 2.1) would have shown thrust.
The Mach Effect transient mass fluctuation is described as being a side effect of having to communicate with the rest of the mass in the distant universe via a similar advanced/retarded wave mechanism as the one used in Wheeler-Feynman Absorber theory, which is used to explain why that gravitational inertial interaction with matter many light years away can be done instantaneously.
With that said, I think any criticism of the third part of Woodward's Paper first has to explain why the Mach Effect transient mass fluctuation, as described by Woodward, either doesn't exist; or could not have the behavior described.
Personally, I believe if one of the components in a device governed by Mach Effects is actually altering its Mass periodically. Then the Kinetic energy for that component also varies. If the Kinetic energy for that component is varying then I don't think it is automatically invalid for Woodward to make the assumptions made in what you call part 3 of your report. -
#1055 by birchoff on 27 Sep, 2016 14:48
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The Mach Effect Thruster has always bothered me as the classical analogue clearly results in no thrust.
I can imagine something similar to a metronome fixed to a spaceship, with a sliding weight that moves up and down the pendulum depending on the direction of the swing. Obviously, this will always result in a net 0 movement in any direction for the spaceship. Acknowledging that electrons and the weight are different animals and my knowledge of physics at the level of the electron is laughably small, I can't see how it could possibly work.
The problem is we keep treating the capacitor analogy as if it is an accurate representation of how the mass fluctuates in a device governed by ME. the capacitor analogy is an oversimplification meant to illustrate that the mass is fluctuating not how the mass fluctuates in the first place. It's the same reason supporters end up talking about Rockets. Every time one is used you will notice a bunch of constraints put on the behavior of the rocket. I believe this is being done because like a Rocket the fluctuating mass component changes its mass. However, unlike a rocket that mass is not lost forever. It is my understanding that it is made to fluctuate in the following manner; when the ship powered by an ME device is at rest , t0, the Fluctuating Mass component is at its rest mass (FMCrm). at t1 the Fluctuating Mass component moved from FMCrm to FMCrm+dM. Then at t2 the Fluctuating Mass component moves from FMCrm+dM to FMCrm-dM. Now I have always assumed that dM is fixed in the device, mainly because if it wasn't Woodward would have been able to show a self-levitating demo. However, I recently realized that his theory doesn't forbid being able to dynamically change the magnitude of dM during operation of an ME device. The only open question is what is the theoretical upper and lower bound on the magnitude of dM. The ability to change the magnitude of dM during operation is important because if you cannot do that each stroke of the actuator pushing on the FMC when it is heavier and pulling on it when it is lighter should yield less and less unidirectional force over the acceleration period. This should be so because unless there is technology to enable this. The actuator doing the pushing and pulling can only do this with a fixed or maximum amount of force. So eventually the fluctuating Kinetic Energy in the FMC will be too much for the actuator to push against; since the FMC is being pulled in the direction of motion of the ship and pushed in the opposite direction of motion of the ship. -
#1056 by Monomorphic on 27 Sep, 2016 15:06
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Has anyone considered CNC metal spinning?
That has been discussed before. My understanding with CNC metal spinning is that a die cast is used to form the metal onto. That is part of the reason I chose whole integers for the spherical radii of my endplates. 50cm and 25cm. I figure there are already die casts of spheres of those dimensions. I'm also looking into building or buying a spherometer.
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#1057 by jaydurst on 27 Sep, 2016 16:55
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Quote
It is my understanding that it is made to fluctuate in the following manner; when the ship powered by an ME device is at rest , t0, the Fluctuating Mass component is at its rest mass (FMCrm). at t1 the Fluctuating Mass component moved from FMCrm to FMCrm+dM. Then at t2 the Fluctuating Mass component moves from FMCrm+dM to FMCrm-dM.
If we consider the metronome (bad) analogue, it's the fluctuation process of the mass that results in the zero net thrust. From the layman's perspective (mine), the electrons moving out of the capacitor would seem to cause the forces to net to zero if we considered them little balls of mass, but, again, the analogy is poor at best, and likely just wrong.
Back to the peanut gallery for me. -
#1058 by Bob012345 on 27 Sep, 2016 17:00
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Gilbertdrive writes;
QuoteBut, as Shawyer calculates the imput power of the emdrive, he founds an enormous 6,04*10^20 Joules, he is happy and he considers that CoE is verified.
That is where the important point here. Shawyer admit that the Kinetic Energy in the Earth referential can not be superior to the energy spent by the ship. He just forgot to take into account his own theory in his thrust formula, and than, he made a mistake in calculating the imput power. (I calculated 6.311*10^13 Joules for 10 years of operation of the 200KwE generator, not taking into account the fact that the time goes more slowly for the ship.
No, I don't think he forgot anything. If he did then the reviewers did too which is unlikely. Shawyer's reduction in thrust as I understand it, is due to the cavity not supporting the acceleration, not actual speeds but regardless, his energy calculation for his probe allows continuous acceleration reduced by relativistic effects.
It is an authority argument. "If it is published, there is no big mistake"
At least, you should concede that the reviewer who accepted the Kinetic Energy to be calculated by 1/2*mv² for a speed of 0,67C made here a mistake, since the relativist formula was needed. The aim was to calculate a ratio that is around 0,31. so the relativist formula was making a real difference.
Also, the main point of my intervention was to show that in Shawyer theory paper, the thrust is supposed to decrease as acceleration from the time frame of the departure of the ship was increasing, so that CoE is verified. Are you convinced by the extracts that I have given, or do you think that, is this paper theory, the force is supposed to be constant ?
Here, the question is not what is true, it is what Shawyer is saying. Once we will agree on what Shawyer is saying in his theory paper, we can go to the other debate.
I agree he should have used relativistic kinetic energy if he applied relativistic effects to the cavity dynamics but then to be entirely consistent the integration over time would need to be done on both sides of the relation and things would get messy and mostly cancel out anyway. His probe is conceptual, not a precise mission plan so it doesn't matter much for this paper. I agree we are discussing what he is saying. In that vein, my thoughts follow.
In his earlier work, Shawyer showed how acceleration can collapse Q and thus force which the collapses acceleration. Looking at the papers you referenced, it's very clear that Shawyer was discussing energy conservation in relation to how the cavity can support a acceleration as the acceleration effects Q and not energy conservation as we have been debating with regards to fundamental considerations of classical mechanics that apply to all situations with a constant force. Not also that the velocity in figure 3.1 is the average velocity over the whole trip, not the instantaneous velocity.
In his later work Shawyer developed and discusses compensation techniques that allow the cavity to maintain a constant acceleration over the whole trip (or at least nearly so allowing a terminal velocity of 0.67c at the target star). It is in this context that he designed the parameters of his Interstellar Probe. I do not believe he forget anything as you suggested.
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#1059 by birchoff on 27 Sep, 2016 17:26
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Quote
It is my understanding that it is made to fluctuate in the following manner; when the ship powered by an ME device is at rest , t0, the Fluctuating Mass component is at its rest mass (FMCrm). at t1 the Fluctuating Mass component moved from FMCrm to FMCrm+dM. Then at t2 the Fluctuating Mass component moves from FMCrm+dM to FMCrm-dM.
If we consider the metronome (bad) analogue, it's the fluctuation process of the mass that results in the zero net thrust. From the layman's perspective (mine), the electrons moving out of the capacitor would seem to cause the forces to net to zero if we considered them little balls of mass, but, again, the analogy is poor at best, and likely just wrong.
Back to the peanut gallery for me.
You are correct, simply fluctuating the mass doesn't yield a net force. Which is why another requirement for getting net force is that you manage to push on the FMC (Fluctuating Mass Component) while it is heavier and pull on the FMC when it is lighter. A much better analogy would be rowing a boat; where the extraction phase is similar to pushing on the FMC while its mass is heavier and the retraction phase is similar to pulling on the FMC when it is lighter. It's the reason I used it to illustrate my understanding of what is going on here. If you want an accurate description of how you manage to push and pull on the FMC at the right time please see the papers linked to here.
