-
#1640 by Gilbertdrive on 14 Oct, 2016 11:22
-
Well, it's friday morning, I swear nothing stronger than tea has passed my lips for more than 24 hours, and yet still I think it's about time to provoke some weekend fun, with a hypothesis 'du jour'.
1. The vacuum is not immutable
2. It is like a frictionless fluid which has both a local mass density and velocity field
3. Its mass density is almost entirely uniform, because non-uniformity dissipates very quickly
4. Consequently the net gravitational effect of the vacuum on any object is almost entirely nil, and the mass of the vacuum is undetectable in the lab.
5. The EMdrive works by transferring momentum to the vacuum, creating a 'flow' of massive vacuum.
6. However, the vacuum is special: we cannot detect motion through the vacuum. Once it is moving, it has 'dark momentum' - actually I quite like that name. 'dark momentum' is inherent in 'dark matter' after all...
7. Similarly, variations in the local mass-density of the vacuum on astronomical scales might account for 'dark matter'.
8. The EMdrive is propellant-less much like an Ocean Liner: it finds its reaction mass in its path. It is indeed not a rocket.
9. Gradients in the local velocity field of the vacuum caused by the EMdrive might cause local gravitational effects, which would be expected to dissipate quickly, much like the wake of a ship. However, a ship is not limited in its thrust to power ratio by the energy to momentum ratio of the waves which dissipate its wake. Nature takes as long as it needs to do that.
Anyway: I know this is not an 'explanation' of the EMdrive or Dark Matter, but it does have explanatory power and more than a hint of Occam's razor about it. When we look for dark matter and find nothing, the answer is obvious if slightly tautologous - 'nothing' has mass....
I guess now is when I'm told about the glaring mistake...
Why not ? I love theories.
But I am not sure I have understood all the implications of this theory. For example, I do not see the link between 3 and 4. The fact that the mass density is uniform should not justify that there is no gravity effect. (The vacuum catastrophe)
Also, I am not sure than 3 and 6 are compatible. If any non uniformity of the quantuum vacuum dissipates quickly, it would be logical that the dark momentum also dissipates quickly.
By The Way, a general question about Quantuum Vacuum. Is there an experimental evidence that the density of Quantuum vacuum is the same in deep space than in laboratory on earth ?
For example, the density of Quantuum Vacuum is lower between 2 mirrors (the casimir effect)
Should it be compatible with known experiments that the density of Quantuum vacuum is lower in deep space ? I know it is not supposed to be the case, but is it also against experimental evidence ? -
#1641 by Gilbertdrive on 14 Oct, 2016 11:25
-
I also do not beleive that Shawyer will give us flying cars in 2017.
What about a propellerless / jetless winged drone?
What order of magnitude for the weight of the jetless winged drone ? What order of thrust ?
Say 50kg thrust or 500N which at specific force 10, 000N/kWrf would need 50Wrf.
And the mass of the device/mass of the drone ? -
#1642 by OnlyMe on 14 Oct, 2016 11:56
-
I do also have a copy of that paper and ran across it when trying to find where I came up with treating the kinetic energy of a spaceship as fictitious. But no cigars here either.
Really I think it best to leave things with the last sentence in my last post on the issue. Since January of this year I have been dealing with a situation that has had a significant impact on my ability, and perhaps the patience required, to spend the time and effort most of these papers deserve. Considering the circumstances it would not be unreasonable to assume that I might even at times have difficulty separating my own random associations while reading a technical paper or report with the report itself.
What I am getting at is that even though I have a clear memory of having read a report/paper that treated the kinetic energy of a spaceship as fictitious, I also recognize that it is entirely possible that, that is a false memory conflating my own random thoughts and extrapolations with the content of the paper I was reading at the time. In the future I will attempt to dig out the reference before posting, when possible.
I still feel that (without reference) the kinetic energy of a rocket (spaceship or even EMDrive), as defined from any frame of reference other than that of the rocket, has nothing to do with how the rocket's propulsion system functions. The rate and results of combustion are not affected by the rocket's velocity associated kinetic energy.
Ask to the dinosaurians if the Kinetic energy of the asteroid that killed them was fictitious.
The Kinetic Energy is a given referential is very concrete when there is a collision.
For example, the Kinetic Energy of an asteroid in the earth referential is very relevant when the asteroid hit the earth.
If somebody shots on me, the Kinetic energy of the bullet in my reference frame will seem very relevant of my point of view.
The fact that the Kinetic Energy is frame dependent does not means at all that it is not very usefull, and relevant.
Anyway, in GR, everything has frame dependance. That is why the name of relativity because almost everything is relative to a reference frame.
The time is frame dependent.
The distances are frame dependent (an observer that cross the solar system at 0,9C will see smaller distances)
The speeds are frame dependent. (and that is because of that that the Kinetic Energy is frame dependant)
The relativistic mass are frame dependent.
The rest mass is not.
With your way of thinking, almost everything would be fictitious.
The only thing not fictitious that I could ask to a girl about her would be her rest mass. Not sure it is the best thing to do.
Also, it is true that the rate and results of combusion are not affected by the Kinetic Energy of a rocket, but that is taking the things in the wrong way. That is the Kinetic Energy of the rocket that is directly affected by the rate of the combustion. A sugar rocket will get less Kinetic Energy than a metane/Lox rocket.
That is also true that the consideration of the rocket alone in the earth referential is not adapted, you have to take into account the rocket propellant.
Kinetic energy is important to collisions. For the case of rockets and even EMDrives being discussed any frame dependent kinetic energy they gain after take off is not related to either colliding with the earth.
You mention relativistic mass which is far closer to my point. On that I refer you to the following...
The Concept of Mass, by Lev Okun http://www.hysafe.org/science/KareemChin/PhysicsToday_v42_p31to36.pdf
And
On the Abuse and Use of Relativistic Mass, by Gary Oas https://arxiv.org/abs/physics/0504110
A bullet does not gain mass because it is moving. Even the discussion over the concept that heat adds to an object's mass is theoretical, and if true unmeasureable at present.
Most of the debate about the velocity and acceleration related aspects of a rocket or EMDrive, does not require the inclusion of kinetic energy associated with velocity or acceleration. In the case of a rocket, the propellant combusts in the rocket's frame of reference and any kinetic energy associated with the rocket's velocity relative to any inertial frame of reference (other than the rockets should it be in an inertial state), does not change the energy or force the rocket drives from the fuel's combustion. To the extent that the combustion chamber is not fully contained, it could be argued that at some rate of acceleration the rocket would be moving away from the point of combustion fast enough to adversely affect efficiency, but I am unsure a chemical rock could produce that kind of acceleration even in deep space.
It seems to me that kinetic energy was introduced in attempts to address the issues of conservation of momentum CoM and conservation of energy CoE. From frames of reference other than that of the rocket or EMDrive. That would only be relevant if one attempts to harvest energy from the acceleration or acquired velocity, within the context of a lab or the earth's frame. Once the system (rocket or EMDrive), is separated from our preferred inertial frame, the earth, either by distance or having reached escape velocity, it would take additional work to do the harvesting.
-
#1643 by Chrochne on 14 Oct, 2016 12:17
-
Good morning guys,
Intreview with Rorger Shawyer went live. There is really a lot of interesting information there!
http://www.ibtimes.co.uk/emdrive-exclusive-roger-shawyer-confirms-mod-dod-interested-controversial-space-propulsion-tech-1586392
-
#1644 by Gilbertdrive on 14 Oct, 2016 12:28
-
Kinetic energy is important to collisions. For the case of rockets and even EMDrives being discussed any frame dependent kinetic energy they gain after take off is not related to either colliding with the earth.
You mention relativistic mass which is far closer to my point. On that I refer you to the following...
The Concept of Mass, by Lev Okun http://www.hysafe.org/science/KareemChin/PhysicsToday_v42_p31to36.pdf
And
On the Abuse and Use of Relativistic Mass, by Gary Oas https://arxiv.org/abs/physics/0504110
A bullet does not gain mass because it is moving. Even the discussion over the concept that heat adds to an object's mass is theoretical, and if true unmeasureable at present.
Most of the debate about the velocity and acceleration related aspects of a rocket or EMDrive, does not require the inclusion of kinetic energy associated with velocity or acceleration. In the case of a rocket, the propellant combusts in the rocket's frame of reference and any kinetic energy associated with the rocket's velocity relative to any inertial frame of reference (other than the rockets should it be in an inertial state), does not change the energy or force the rocket drives from the fuel's combustion. To the extent that the combustion chamber is not fully contained, it could be argued that at some rate of acceleration the rocket would be moving away from the point of combustion fast enough to adversely affect efficiency, but I am unsure a chemical rock could produce that kind of acceleration even in deep space.
It seems to me that kinetic energy was introduced in attempts to address the issues of conservation of momentum CoM and conservation of energy CoE. From frames of reference other than that of the rocket or EMDrive. That would only be relevant if one attempts to harvest energy from the acceleration or acquired velocity, within the context of a lab or the earth's frame. Once the system (rocket or EMDrive), is separated from our preferred inertial frame, the earth, either by distance or having reached escape velocity, it would take additional work to do the harvesting.
Even if I remove the relativistic mass from the list, it still makes many things fictititous in your way of thinking.
An Emship can go at alpha century, and come back and hit the earth. At this moment, according to you, the Kinetic Energy is relevant.
Since an encounter is one day possible, the Kinetic energy has to be relevant during all the way.
Kinetic Energy, even if it is frame dependent, is something very usefull in physics, and that is perfectly consistent. So, it can be calculated.
Also, you are right saying that you do not need to use CoE when you calculate the trajectory of a rocket. If you read carefully what has been written, we do not use CoE to calculate the trajectory. We describe how the rocket works, in a way that it is perfectly consistent with CoE.
Also, the Kinetic Energy in a reference frame is only defined by the speed in this reference frame, and the mass.
If you think that Kinetic Energy is ficticitous, that means that speed is also fictitious.
I realy do not see the point. Why something frame dependent would be fictitious ?
In fact, I think that there is a misunderstanding about the word fictitious. It is too vague.
Can you tell what this word implies ?
For example :
-Useless ?
-inconsistent ?
-incoherent ?
Or something else ? -
#1645 by TheTraveller on 14 Oct, 2016 12:46
-
EmDrive exclusive: Roger Shawyer confirms MoD and DoD interested in controversial space propulsion tech
http://www.ibtimes.co.uk/emdrive-exclusive-roger-shawyer-confirms-mod-dod-interested-controversial-space-propulsion-tech-1586392
Uncut interview:
JV with Gilo Industries confirmef. -
#1646 by Monomorphic on 14 Oct, 2016 12:52
-
Monomorphic -
The comment that the fields in your simulation of Shawyer's new frustrum are above the breakdown potential gradient in dry air doesn't seem to have got a lot of airtime, but it does seem that the whole solution can't be valid because of that.
Are these runs being done with the cavity implicitly vacuum? Does FEKO allow the cavity to be filled with air as a dielectric, and can it compute the consequences of breakdown in that case?
FEKO assumes a vacuum. I could fill the cavity with a dialectric with the properties of air, but I do not believe FEKO computes the consequences of breakdown. -
#1647 by Monomorphic on 14 Oct, 2016 13:00
-
EmDrive exclusive: Roger Shawyer confirms MoD and DoD interested in controversial space propulsion tech
http://www.ibtimes.co.uk/emdrive-exclusive-roger-shawyer-confirms-mod-dod-interested-controversial-space-propulsion-tech-1586392
I liked Roger's comment about internet trolls.
-
#1648 by Flyby on 14 Oct, 2016 13:03
-
I am a bit sad to hear the confirmation of the right-out abusive language he had to endure.
Call me naive, but i never understood it : You can perfectly disagree with people in a polite and even constructive way... so, why does it have to be hateful and destructive?
Regardless whether it is a greatest invention or the greatest hoax of the 21th century, there is never a reason to attack somebody on a personal level. Challenge his theories, question his experimental results, but it is a very very low form of skepticism when you have to resort to personal attacks to tear down an idea or claim.
However, the video did not change my skepticism and that will remain so, till I can really see a working EMdrive that can only be explained through an EM effect (whatever that may be).
Like most people inhere, I keep an open mind to it, patiently waiting, but I want to see clear, crisp results...
-
#1649 by Flyby on 14 Oct, 2016 14:00
-
EmDrive works.
Roger's theory works.
Accept it.
Get over it.
Move on.
There is nothing "to get over", simply because I'm not against it...
Words and claims are cheap these days, but show us that it works...and I'll gladly embrace it.
You still don't get it do you?
A lot of people inhere are NOT against the EMdrive. They just don't want to jump the gun, based upon inconclusive "evidence" or what might "possibly be a valid signal".
The reason why we/I keep discussing it inhere is because there is that intriguing possibility that it might indeed work.
But...Skepticism is an absolute requirement for scientific rigor. period.
You may not like it, but it is a very needed obstacle on your path, to ensure that you're going in the right direction...
If it wasn't for my obvious lack of knowledge on electronics, I would have started building myself more then a year ago. Just to satisfy my curiosity, because I do find it a very intriguing concept. But as often warned inhere, if you're not knowing what you're doing , it is better not to start a DIY build...And that's exactly why I didn't...
so really, all I want is to see a working setup that has addressed all of the previous remarks and Roger/you/or any other DIY will get all the thumbs up he/she deserves from me... -
#1650 by OnlyMe on 14 Oct, 2016 14:32
-
Kinetic energy is important to collisions. For the case of rockets and even EMDrives being discussed any frame dependent kinetic energy they gain after take off is not related to either colliding with the earth.
You mention relativistic mass which is far closer to my point. On that I refer you to the following...
The Concept of Mass, by Lev Okun http://www.hysafe.org/science/KareemChin/PhysicsToday_v42_p31to36.pdf
And
On the Abuse and Use of Relativistic Mass, by Gary Oas https://arxiv.org/abs/physics/0504110
A bullet does not gain mass because it is moving. Even the discussion over the concept that heat adds to an object's mass is theoretical, and if true unmeasureable at present.
Most of the debate about the velocity and acceleration related aspects of a rocket or EMDrive, does not require the inclusion of kinetic energy associated with velocity or acceleration. In the case of a rocket, the propellant combusts in the rocket's frame of reference and any kinetic energy associated with the rocket's velocity relative to any inertial frame of reference (other than the rockets should it be in an inertial state), does not change the energy or force the rocket drives from the fuel's combustion. To the extent that the combustion chamber is not fully contained, it could be argued that at some rate of acceleration the rocket would be moving away from the point of combustion fast enough to adversely affect efficiency, but I am unsure a chemical rock could produce that kind of acceleration even in deep space.
It seems to me that kinetic energy was introduced in attempts to address the issues of conservation of momentum CoM and conservation of energy CoE. From frames of reference other than that of the rocket or EMDrive. That would only be relevant if one attempts to harvest energy from the acceleration or acquired velocity, within the context of a lab or the earth's frame. Once the system (rocket or EMDrive), is separated from our preferred inertial frame, the earth, either by distance or having reached escape velocity, it would take additional work to do the harvesting.
Even if I remove the relativistic mass from the list, it still makes many things fictititous in your way of thinking.
An Emship can go at alpha century, and come back and hit the earth. At this moment, according to you, the Kinetic Energy is relevant.
Since an encounter is one day possible, the Kinetic energy has to be relevant during all the way.
Kinetic Energy, even if it is frame dependent, is something very usefull in physics, and that is perfectly consistent. So, it can be calculated.
Also, you are right saying that you do not need to use CoE when you calculate the trajectory of a rocket. If you read carefully what has been written, we do not use CoE to calculate the trajectory. We describe how the rocket works, in a way that it is perfectly consistent with CoE.
Also, the Kinetic Energy in a reference frame is only defined by the speed in this reference frame, and the mass.
If you think that Kinetic Energy is ficticitous, that means that speed is also fictitious.
I realy do not see the point. Why something frame dependent would be fictitious ?
In fact, I think that there is a misunderstanding about the word fictitious. It is too vague.
Can you tell what this word implies ?
For example :
-Useless ?
-inconsistent ?
-incoherent ?
Or something else ?
Forget the word fictitious. In a response to Dr. Rodal and I think again to meberbs, I admitted that I could not recall the reference I thought it came from and that my use was not clear... or words to that effect.
For now I would say unnecessary to overly complicating, for the discussion.
Neglecting the effect of gravity you can calculate the rate of acceleration with nothing more than the mass and force involved. The acceleration/velocity dependent kinetic energy does not change the result. Including it only complicates things, because it is different from different frames of reference... and it is only important when you are evaluating a collision of masses, or if you are assuming an external force of resistance like moving through water or air.., or even friction between the wheels of a car and a road. Even then you must clearly define the resistance.
Gravity is important to the issue of a third stage of a rocket, producing more kinetic energy than earlier stages, because it is the decreasing gravitational resistance that causes the later stages to appear to be more efficient. They are doing work against a diminishing gravitational field.
Since velocity related kinetic energy does not affect the efficiency of combustion, including it in the calculations just complicates any attempt to reconcile CoM/CoE. -
#1651 by bmcgaffey20 on 14 Oct, 2016 14:37
-
I also do not beleive that Shawyer will give us flying cars in 2017.
What about a propellerless / jetless winged drone?
What order of magnitude for the weight of the jetless winged drone ? What order of thrust ?
Say 50kg thrust or 500N which at specific force 10, 000N/kWrf would need 50Wrf.
I keep seeing you mention this number, however; if anyone had achieved that specific force we wouldn't still be arguing about whether or not the signal is an anomaly. -
#1652 by meberbs on 14 Oct, 2016 14:43
-
Egan did a derivation directly from Maxwell's equations (the same ones Cullen used), and you have never pointed out a single flaw in the derivation. And unlike your statement, he does find that there is a different force on the end walls, he just also finds that there is an exactly balancing force on the sidewalls. Anyone with experience working in electromagnetism would recognize that there would be an expectation of force on the side walls as well.http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html
The Egan analysis is a work of fiction that does not recognise the guide wavelength alters as the frustum diameter alters and worse still that the EmWave momemtum alters as the guide wavelength alters.
To show a systems is open, all you have to do is point out something else it interacts with or show something entering or leaving the system.A response from THE man himself. Very prompt too. You must be watching these forums very closely!
Maybe General Relativity is involved and your Eureka moment is correct. General Relativity (and several other possible effects) would make this an open system, which would nullify all the conservation of energy arguments being made in NSF pages that deal with conservation of energy as a closed system and ignoring gravitational effects.
So you are saying the device doesn't scale? lol. btw-- thank you for correcting me, I thought I had a eureka moment in understanding the device. Obviously, less than amateur enthusiast here!!
The conservation of energy arguments being made would be like somebody claiming that a Gravity Assist maneuver is impossible, because a spacecraft considered as a closed system, where gravity is ignored, would be breaking conservation of energy in a swing-by maneuver.
I just wanted to clarify what Shawyer maintains, and in no way do I now or I have ever agreed with Shawyer's explanation
http://emdrive.com/faq.htmlQuote2.
Q. How can a net force be produced by a closed waveguide?
A. At the propagation velocities (greater than one tenth the speed of light) the effects of special relativity must be considered. Different reference planes have to be used for the EM wave and the waveguide itself. The thruster is therefore an open system and a net force can be produced.
Shawer does not do this, so the first part of the statement might as well be "the sky is blue." It does nothing to show that the emDrive is an open system. (other theoriesthan Shawyer's point out ways for the emDrive to be an open system, but these require new physics that Shawyer doesn't think is necessary.An EmDrive generates 2 forces that can be measures but not at the same time nor with the same test setup:
You don't seem to understand what a force is.
1) Thrust force with a vector small to big that is the result of the differential radiation pressure on the end plates. This is a static force that can be measured with a scale.
2) Reaction force with a vector big to small and is the equal but opposite force to the Thrust force. This is a dynamic force and can only be measured during free acceleration.
Roger has measured both forces and has shown that they are approx equal in force amplitude but opposite in force vector direction.
Let's go with a simple mechanical analogue that produces the exact same types of forces that Shawyer claims (assuming there is no force on the sidewalls and the EM waves somehow change momentum as they travel down the cavity without transferring that momentum to the cavity):
-Take a cart with wheels on it that let it roll without negligible friction.
-Put a small plate on the front end and a large plate on the back end (plate size doesn't actually matter except for keeping track which end corresponds to which end of the emDrive)
-Have some device in the middle not attached to the cart that bounces rubber balls off of the plates.
-The device bounces low momentum balls off of the small plate and high momentum balls off of the large plate, catching them on the rebound to change their momentum before firing them again
-External forces move the device to keep the device in between the plates moving however the cart moves and balancing momentum from the balls it catches.
So in this system (which is not difficult to set up and test) which direction would the cart move in?
How would you describe the forces involved? -
#1653 by Gilbertdrive on 14 Oct, 2016 14:47
-
Kinetic energy is important to collisions. For the case of rockets and even EMDrives being discussed any frame dependent kinetic energy they gain after take off is not related to either colliding with the earth.
You mention relativistic mass which is far closer to my point. On that I refer you to the following...
The Concept of Mass, by Lev Okun http://www.hysafe.org/science/KareemChin/PhysicsToday_v42_p31to36.pdf
And
On the Abuse and Use of Relativistic Mass, by Gary Oas https://arxiv.org/abs/physics/0504110
A bullet does not gain mass because it is moving. Even the discussion over the concept that heat adds to an object's mass is theoretical, and if true unmeasureable at present.
Most of the debate about the velocity and acceleration related aspects of a rocket or EMDrive, does not require the inclusion of kinetic energy associated with velocity or acceleration. In the case of a rocket, the propellant combusts in the rocket's frame of reference and any kinetic energy associated with the rocket's velocity relative to any inertial frame of reference (other than the rockets should it be in an inertial state), does not change the energy or force the rocket drives from the fuel's combustion. To the extent that the combustion chamber is not fully contained, it could be argued that at some rate of acceleration the rocket would be moving away from the point of combustion fast enough to adversely affect efficiency, but I am unsure a chemical rock could produce that kind of acceleration even in deep space.
It seems to me that kinetic energy was introduced in attempts to address the issues of conservation of momentum CoM and conservation of energy CoE. From frames of reference other than that of the rocket or EMDrive. That would only be relevant if one attempts to harvest energy from the acceleration or acquired velocity, within the context of a lab or the earth's frame. Once the system (rocket or EMDrive), is separated from our preferred inertial frame, the earth, either by distance or having reached escape velocity, it would take additional work to do the harvesting.
Even if I remove the relativistic mass from the list, it still makes many things fictititous in your way of thinking.
An Emship can go at alpha century, and come back and hit the earth. At this moment, according to you, the Kinetic Energy is relevant.
Since an encounter is one day possible, the Kinetic energy has to be relevant during all the way.
Kinetic Energy, even if it is frame dependent, is something very usefull in physics, and that is perfectly consistent. So, it can be calculated.
Also, you are right saying that you do not need to use CoE when you calculate the trajectory of a rocket. If you read carefully what has been written, we do not use CoE to calculate the trajectory. We describe how the rocket works, in a way that it is perfectly consistent with CoE.
Also, the Kinetic Energy in a reference frame is only defined by the speed in this reference frame, and the mass.
If you think that Kinetic Energy is ficticitous, that means that speed is also fictitious.
I realy do not see the point. Why something frame dependent would be fictitious ?
In fact, I think that there is a misunderstanding about the word fictitious. It is too vague.
Can you tell what this word implies ?
For example :
-Useless ?
-inconsistent ?
-incoherent ?
Or something else ?
Forget the word fictitious. In a response to Dr. Rodal and I think again to meberbs, I admitted that I could not recall the reference I thought it came from and that my use was not clear... or words to that effect.
For now I would say unnecessary to overly complicating, for the discussion.
Neglecting the effect of gravity you can calculate the rate of acceleration with nothing more than the mass and force involved. The acceleration/velocity dependent kinetic energy does not change the result. Including it only complicates things, because it is different from different frames of reference... and it is only important when you are evaluating a collision of masses, or if you are assuming an external force of resistance like moving through water or air.., or even friction between the wheels of a car and a road. Even then you must clearly define the resistance.
Gravity is important to the issue of a third stage of a rocket, producing more kinetic energy than earlier stages, because it is the decreasing gravitational resistance that causes the later stages to appear to be more efficient. They are doing work against a diminishing gravitational field.
Since velocity related kinetic energy does not affect the efficiency of combustion, including it in the calculations just complicates any attempt to reconcile CoM/CoE.
I better understand now.
Kinetic Energy is still usefull to verify that there was no miscalculation. Even if there is no imminent collision, it can be calculated to verify the calculus that has been done before.
About the upper stage, the question was about it's Kinetic energy, and an apparent paradox (that was solved)
By definition, we can not solve an apparent paradox about Kinetic energy without speaking of Kinetic Energy.
And there was nothing complicate about CoE and COM and upper stage. Just have to take into account the Kinetic energy of the propellant. Nothing to do with gravity well. At the opposite, even for the upper stage, the Gravity well lowers the final Kinetic Energy, and the apparent paradox was that this final Kinetic energy was higher than expected. So, the diminishing gravitational field was not the explanation. At the opposite, the paradox was bigger if it was taken into account !
I do not understand how you can say that
Since velocity related kinetic energy does not affect the efficiency of combustion, including it in the calculations just complicates any attempt to reconcile CoM/CoE.
You just can not evaluate if something respect CoE without taking into account Kinetic Energy. Of course, even if you do not speak about Kinetic Energy, and apply mecanics, the result will still respect CoE, but you can not discuss the satisfaction of CoE without taking into account Kinetic energy. Kinetic energy is not, in this precise case, a complication, it is the main point. -
#1654 by OnlyMe on 14 Oct, 2016 16:05
-
....
I better understand now.
Kinetic Energy is still usefull to verify that there was no miscalculation. Even if there is no imminent collision, it can be calculated to verify the calculus that has been done before.
About the upper stage, the question was about it's Kinetic energy, and an apparent paradox (that was solved)
By definition, we can not solve an apparent paradox about Kinetic energy without speaking of Kinetic Energy.
And there was nothing complicate about CoE and COM and upper stage. Just have to take into account the Kinetic energy of the propellant. Nothing to do with gravity well. At the opposite, even for the upper stage, the Gravity well lowers the final Kinetic Energy, and the apparent paradox was that this final Kinetic energy was higher than expected. So, the diminishing gravitational field was not the explanation. At the opposite, the paradox was bigger if it was taken into account !
I do not understand how you can say that
Since velocity related kinetic energy does not affect the efficiency of combustion, including it in the calculations just complicates any attempt to reconcile CoM/CoE.
You just can not evaluate if something respect CoE without taking into account Kinetic Energy. Of course, even if you do not speak about Kinetic Energy, and apply mecanics, the result will still respect CoE, but you can not discuss the satisfaction of CoE without taking into account Kinetic energy. Kinetic energy is not, in this precise case, a complication, it is the main point.
Trying to simplify it as much as possible...
You launch a rocket from earth toward mars. If you calculate its kinetic energy from the frames of reference of; the earth, moon, sun, and mars etc., you get different values. Even values that change constantly over time. And in all frames the fuel consumption is the same and the force and accelerations, as experienced in the rocket's frame of reference winds up the same. Even the time the trip takes in all frames winds up the same. Relativistic effect are insignificantly small at the velocities, distance and time involved.
The kinetic energy will always balance out because it is the product of the mass and acceleration of the rocket in its own frame. Adding kinetic energy may be a good exercise mathematically, but it is unnecessary and over complicates the process, when it is certain that CoM and CoE are conserved in the rocket's frame where the kinetic energy is zero, it is conserved in all frames.
Your third stage argument falls apart if you take gravity out of the picture. It is not a real world problem. As the rocket moves out of the gravity well less force goes to overcoming gravity and directly toward overcoming inertia. At classical velocities and accelerations inertia is insignificant compared with gravity.
If in the rocket's frame, where there is no kinetic energy to deal with, energy is conserved, and your calculations that include kinetic energy disagree, there is a problem.
Maybe you could explain why you think the third stage out performs the earlier stages? Remember, the math and our models should describe what we observe to be real. They are not the reason things are the way we observe them to be.
P.S. If you must evaluate an accelerating rocket from an inertial frame, including kinetic energy may be important, but the results of calculations from the rocket's frame demonstrating CoE, without the introduction of kinetic energy, are valid in all frames. -
#1655 by bmcgaffey20 on 14 Oct, 2016 16:32
-
....
I better understand now.
Kinetic Energy is still usefull to verify that there was no miscalculation. Even if there is no imminent collision, it can be calculated to verify the calculus that has been done before.
About the upper stage, the question was about it's Kinetic energy, and an apparent paradox (that was solved)
By definition, we can not solve an apparent paradox about Kinetic energy without speaking of Kinetic Energy.
And there was nothing complicate about CoE and COM and upper stage. Just have to take into account the Kinetic energy of the propellant. Nothing to do with gravity well. At the opposite, even for the upper stage, the Gravity well lowers the final Kinetic Energy, and the apparent paradox was that this final Kinetic energy was higher than expected. So, the diminishing gravitational field was not the explanation. At the opposite, the paradox was bigger if it was taken into account !
I do not understand how you can say that
Since velocity related kinetic energy does not affect the efficiency of combustion, including it in the calculations just complicates any attempt to reconcile CoM/CoE.
You just can not evaluate if something respect CoE without taking into account Kinetic Energy. Of course, even if you do not speak about Kinetic Energy, and apply mecanics, the result will still respect CoE, but you can not discuss the satisfaction of CoE without taking into account Kinetic energy. Kinetic energy is not, in this precise case, a complication, it is the main point.
Trying to simplify it as much as possible...
You launch a rocket from earth toward mars. If you calculate its kinetic energy from the frames of reference of; the earth, moon, sun, and mars etc., you get different values. Even values that change constantly over time. And in all frames the fuel consumption is the same and the force and accelerations, as experienced in the rocket's frame of reference winds up the same. Even the time the trip takes in all frames winds up the same. Relativistic effect are insignificantly small at the velocities, distance and time involved.
The kinetic energy will always balance out because it is the product of the mass and acceleration of the rocket in its own frame. Adding kinetic energy may be a good exercise mathematically, but it is unnecessary and over complicates the process, when it is certain that CoM and CoE are conserved in the rocket's frame where the kinetic energy is zero, it is conserved in all frames.
Your third stage argument falls apart if you take gravity out of the picture. It is not a real world problem. As the rocket moves out of the gravity well less force goes to overcoming gravity and directly toward overcoming inertia. At classical velocities and accelerations inertia is insignificant compared with gravity.
If in the rocket's frame, where there is no kinetic energy to deal with, energy is conserved, and your calculations that include kinetic energy disagree, there is a problem.
Maybe you could explain why you think the third stage out performs the earlier stages? Remember, the math and our models should describe what we observe to be real. They are not the reason things are the way we observe them to be.
P.S. If you must evaluate an accelerating rocket from an inertial frame, including kinetic energy may be important, but the results of calculations from the rocket's frame demonstrating CoE, without the introduction of kinetic energy, are valid in all frames.
This is pretty off topic. How does the third stage of a rocket relate to the emdrive? CoE? I think not. We are unsure if its even an open or a closed system. Debating those things is fine, but not a conventional rocket. The is not NEW PHYSICS. One post, sure.... 3 pages of it? Knock it off please. -
#1656 by wicoe on 14 Oct, 2016 16:57
-
I have a question (sorry if this has been asked/answered before, I'm new to this forum, and google does not give a definitive answer)... For all known tests that show non-zero thrust, is it always in the same direction? If yes, which direction is that? (i.e. small-to-big or big-to-small)? By "direction of thrust" I mean the direction of force that the EmDrive seems to apply to a measurement device (pendulum, scale, etc).
And a follow-up question: which of the current theories are compatible with this direction without inventing "reaction forces" that can cause the device to accelerate *towards* harder-hitting photons as opposed to away from them? -
#1657 by Tellmeagain on 14 Oct, 2016 17:08
-
I have a question (sorry if this has been asked/answered before, I'm new to this forum, and google does not give a definitive answer)... For all known tests that show non-zero thrust, is it always in the same direction? If yes, which direction is that? (i.e. small-to-big or big-to-small)? By "direction of thrust" I mean the direction of force that the EmDrive seems to apply to a measurement device (pendulum, scale, etc).
And a follow-up question: which of the current theories are compatible with this direction without inventing "reaction forces" that can cause the device to accelerate *towards* harder-hitting photons as opposed to away from them?
No, no consistent directions. That is a big alarming sign. -
#1658 by WarpTech on 14 Oct, 2016 17:08
-
I have a question (sorry if this has been asked/answered before, I'm new to this forum, and google does not give a definitive answer)... For all known tests that show non-zero thrust, is it always in the same direction? If yes, which direction is that? (i.e. small-to-big or big-to-small)? By "direction of thrust" I mean the direction of force that the EmDrive seems to apply to a measurement device (pendulum, scale, etc).
And a follow-up question: which of the current theories are compatible with this direction without inventing "reaction forces" that can cause the device to accelerate *towards* harder-hitting photons as opposed to away from them?
My understanding is that force has been generated in both directions. However, primarily it is with the small end leading. Theoretically, it has to do with the motion of the CM of the field inside the frustum and which way it moves. There is insufficient data to show that thrust in both directions are not artifacts. -
#1659 by Rodal on 14 Oct, 2016 17:09
-
I have a question (sorry if this has been asked/answered before, I'm new to this forum, and google does not give a definitive answer)... For all known tests that show non-zero thrust, is it always in the same direction? If yes, which direction is that? (i.e. small-to-big or big-to-small)? By "direction of thrust" I mean the direction of force that the EmDrive seems to apply to a measurement device (pendulum, scale, etc).
And a follow-up question: which of the current theories are compatible with this direction without inventing "reaction forces" that can cause the device to accelerate *towards* harder-hitting photons as opposed to away from them?
QUESTION: << For all known tests that show non-zero thrust, is it always in the same direction? >> ANSWER: No
COMMENT: NASA is the only research group that has unequivocally verified the mode shape being excited in most of their tests: TM212, with an infrared camera (*). For this specific TM212 mode shape, when using a polymer insert at the small end they have verified that both the measured force and the measured displacement, velocity and accelerations are directed in a vector pointing from the big end towards the small end. At NSF, Paul has also reported that he measured forces and displacements in the opposite direction (from the small end towards the big end) for other mode shapes.
(*) For a perfect conductor (Q->Infinity), the TE0np modes being preferred by other researchers can be exactly shown to lead to zero electric fields at all internal surfaces of the frustum of a spherical cone (http://forum.nasaspaceflight.com/index.php?topic=39214.msg1526577#msg1526577). For an imperfect conductor (finite Q) it can be shown that there are very small surface electric fields within the skin depth of the frustum of a cone for TE0np mode shapes (http://forum.nasaspaceflight.com/index.php?topic=39214.msg1542032#msg1542032). This makes determination of TE0np mode shapes based on an infrared thermal camera difficult. Additionally, TE mode shapes have been known to be much more difficult to excite than TM modes (see classic books like Collin, for example). Numerical methods like Finite Difference (much inferior to FE with respect to satisfying Neumann BC's along a boundary), and Finite Element packages are known not to be able to exactly satisfy Neumann boundary conditions along a boundary and hence their output for current at the surface for TE modes can be shown to be inaccurate. The Neumann boundary conditions may be satisfied only in an integral sense when using a Finite Element program, rather than everywhere along the boundary (particularly when the Finite Element user does not conduct a convergence test, which is the norm for Finite Element analysis being displayed at NSF. I don't ever recall anybody showing Finite Element results here ever showing a convergence analysis displaying the asymptotic approach to a solution). Furthermore it is well known that Finite Element methods that rely on the Galerkin method (as many commonly used programs do) do not satisfy the Neumann boundary conditions as well as methods based on variational principles, or using mixed methods.
