-
#2660 by Rodal on 08 Nov, 2017 14:56
-
There are 2 very major difference in EmDrive torsion arm test rigs.
My recollection from the workshop is that TU Dresden also said that they are working on a torsional rig with lower stiffness (higher compliance) such as to ideally allow a 360 degree turn.
1) allowing sufficient background external forces, vibration, that will generate enough initial small end forward acceleration to trigger the self sustaining Motor mode
2) uN/um sensitivy which defines displacement available to support free acceleration before the torsion wire generates enough back force/torque to stop acceleration and when acceleration stops, thrust generation stops. .
As example the
1) EW test rig rates at 24uN/um
2) Jamie's test rig 0.18uN/um
Jamie's measured 3.5uN is equilivant to 19.4um of free to accelerate displacement.
I suggest 20um is a good number for experimenters to design their torsion rigs to support and don't isolate all the external forces or there will be no thrust generated.
Which says an EmDrive torsion test rig needs to be designed to be EmDrive thrust generation friendly.
Perhaps Todd can also confirm whether he also heard about those plans.
An experiment allowing a big rotation would be interesting to see (present experiments being discussed allow only infinitesimal displacements)
-
#2661 by TheTraveller on 08 Nov, 2017 15:02
-
There are 2 very major difference in EmDrive torsion arm test rigs.
My recollection from the workshop is that TU Dresden also said that they are working on a torsional rig with lower stiffness (higher compliance) such as to ideally allow a 360 degree turn.
1) allowing sufficient background external forces, vibration, that will generate enough initial small end forward acceleration to trigger the self sustaining Motor mode
2) uN/um sensitivy which defines displacement available to support free acceleration before the torsion wire generates enough back force/torque to stop acceleration and when acceleration stops, thrust generation stops. .
As example the
1) EW test rig rates at 24uN/um
2) Jamie's test rig 0.18uN/um
Jamie's measured 3.5uN is equilivant to 19.4um of free to accelerate displacement.
I suggest 20um is a good number for experimenters to design their torsion rigs to support and don't isolate all the external forces or there will be no thrust generated.
Which says an EmDrive torsion test rig needs to be designed to be EmDrive thrust generation friendly.
Perhaps Todd can also confirm whether he also heard about those plans.
An experiment allowing a big rotation would be interesting to see (present experiments being discussed allow only infinitesimal displacements)
Hi Jose,
Good to learn. Still need to know the uN/um sensitivity and that the test rig is not so vibration isolated that there are no precursor small end forward external forces available to trigger Motor mode and self sustaining acceleration.
But YES rotary test rig, allowing at least 360 deg of free acceleration are a superior way to test EmDrives vs scales or torsion test rigs. -
#2662 by PotomacNeuron on 08 Nov, 2017 15:17
-
There are 2 very major difference in EmDrive torsion arm test rigs.
1) allowing sufficient background external forces, vibration, that will generate enough initial small end forward acceleration to trigger the self sustaining Motor mode
My understanding is that this assertion came from Mr. Shawyer's observation that his rotary test rig did not rotate unless he gave it an initial "bang". However, in contrast to this hard to understand assertion, that observation had a much easier interpretation, that an initial bang was needed to overcome the air bearing's low energy resting position ( think of static friction as an analogy ).Quote2) uN/um sensitivy which defines displacement available to support free acceleration before the torsion wire generates enough back force/torque to stop acceleration and when acceleration stops, thrust generation stops. .
If "when acceleration stops, thrust generation stops", since the torsion wire's back force is still there, the torsion balance will swing back. I remembered Mr. Shawyer's rotary test rig swung back from it's furthest reach. Did this assertion come from that observation? If so, however, in contrast to this hard to understand assertion, that observation also had an easier interpretation: A hanging magnetic needle swings back from its furthest reach if released from a high potential energy position.QuoteAs example the
1) EW test rig rates at 24uN/um
2) Jamie's test rig 0.18uN/um
Which says the EW torsion test rig is 133 times stiffer than Jamie's test rig. Being tighter means for the same thrust, the EmDrive would have 133x LESS displacement/movenent to self accelerate and get solidly into Motor mode.
I believe Dave's test rig was looser than Jamie's as his test rig arms were longer. Maybe Dave will provide the uN/um sensitivity for his test rig?
Jamie's measured 3.5uN is equilivant to 19.4um of free to accelerate displacement.
I suggest 20um is a good number for experimenters to design their torsion rigs to support and don't isolate all the external forces or there will be no thrust generated.
Which says an EmDrive torsion test rig needs to be designed to be EmDrive thrust generation friendly.
This assertion is also hard to understand, "don't isolate all the external forces or there will be no thrust generated". Think of gravity. It is always there. If you want an external force on the axle direction, just tilt the frustum with 1 degree of angle. -
#2663 by Rodal on 08 Nov, 2017 15:19
-
...
My recollection is that the TU Dresden torsional testing of the EM Drive had by far the best vibration isolation of any EM Drive tested up to now. They went out of their way to have an expensive new foundation and vibration isolation. I know that this is the opposite of what you advocate, but my understanding is that TU Dresden's intent is to lower all possible sources of noise as much as possible, to be able to measure less than a microNewton.
Hi Jose,
Good to learn. But still need to know the uN/um sensitivity and that the test rig is not so vibration isolated that there are no precursor small end forward external forces available to trigger Motor mode and self sustaining acceleration.
But YES rotary test rig, allowing at least 360 deg of free acceleration are a superior way to test EnDrives vs scales or torsion test rigs.
For example, they tested Aachen's tiny Baby EM Drive (Hackaday). My recollection for the Baby EM Drive is that they did not measure any force above the noise. -
#2664 by TheTraveller on 08 Nov, 2017 15:22
-
This assertion is also hard to understand, "don't isolate all the external forces or there will be no thrust generated". Think of gravity. It is always there. If you want an external force on the axle direction, just tilt the frustum with 1 degree of angle.
Hi PN,
Please read:
http://www.emdrive.com/EmDriveForceMeasurement.pdfQuote4. Practical static measurement techniques
A number of methods have been used in the UK, the US and China to measure the forces produced by an EmDrive thruster.
In each successful case, the EmDrive force data has been superimposed on an increasing or decreasing background force, generated by the test equipment itself.
Indeed, in the UK when the background force changes were eliminated, in an effort to improve force measurement resolution, no EmDrive force was measured.
This was clearly a result of attempting to measure the forces on a fully static thruster, where T and R cancel each other.
UK flight thruster measurements employ this principle to calibrate the background noise on the force balance prior to carrying out force measurements.
What is needed are vibrational forces that can generate a small and very short term small end forward acceleration, which generates the needed internal Doppler shifts to trigger Motor mode and self sustained acceleration.
What is difficult to understand? -
#2665 by meberbs on 08 Nov, 2017 15:59
-
What is difficult to understand?
Two things are difficult to understand:
1. Why you continue quoting a paper that clearly illustrates that the author does not even slightly understand the concept of a force balance or F = m*a.
2. The quoted section of the paper states that the thrust goes away when error sources are eliminated. I am not sure how any conclusion can be drawn from that other than "thrust measurements are due to experimental error." -
#2666 by Bob012345 on 08 Nov, 2017 18:27
-
What is difficult to understand?
Two things are difficult to understand:
1. Why you continue quoting a paper that clearly illustrates that the author does not even slightly understand the concept of a force balance or F = m*a.
2. The quoted section of the paper states that the thrust goes away when error sources are eliminated. I am not sure how any conclusion can be drawn from that other than "thrust measurements are due to experimental error."
The paper is clear enough. He didn't say there was no EMDrive force, he said there was no force measured in his particular setup and he explained why. -
#2667 by PotomacNeuron on 08 Nov, 2017 18:50
-
Hi PN,
Please read:
http://www.emdrive.com/EmDriveForceMeasurement.pdf
I do not understand this document. The meaning is that I can not make it resonate in my brain with physics I have learned. Either it is not consistent with reality, or the physics I have learned does not describe reality, or my brain does not have the ability to relate them. -
#2668 by Bob012345 on 08 Nov, 2017 19:12
-
Hi PN,
Please read:
http://www.emdrive.com/EmDriveForceMeasurement.pdf
I do not understand this document. The meaning is that I can not make it resonate in my brain with physics I have learned. Either it is not consistent with reality, or the physics I have learned does not describe reality, or my brain does not have the ability to relate them.
It made sense to me just fine. Maybe the difference is physics as a physicist describes it vs. experiment as an engineer does it. Both are true but sometimes are expressed in different language.
-
#2669 by mgfitter on 08 Nov, 2017 19:34
-
This may be a dumb question from a layperson here in the peanut gallery, but I can't help wondering...
There appears to be considerable work, time and expense involved in isolating these devices in order to detect tiny thrust levels. Could those resources be better spent in building a larger device designed to produces sufficient thrust to make these noise sources irrelevant?
Could I ask Monomorphic: Roughly how much have you spent (time & money) on all these activities to isolate your system, and how would that compare to trying to make a more powerful system that would be sufficiently powerful that all these noise sources would be inconsequential? Where do you think that line is?
Thanks,
-MG -
#2670 by meberbs on 08 Nov, 2017 19:48
-
I have both physics and engineering backgrounds, and from neither perspective does that paper make sense. It pretty much translates to "pushing a box to the left will make the box move to the right."
Hi PN,
Please read:
http://www.emdrive.com/EmDriveForceMeasurement.pdf
I do not understand this document. The meaning is that I can not make it resonate in my brain with physics I have learned. Either it is not consistent with reality, or the physics I have learned does not describe reality, or my brain does not have the ability to relate them.
It made sense to me just fine. Maybe the difference is physics as a physicist describes it vs. experiment as an engineer does it. Both are true but sometimes are expressed in different language. -
#2671 by Rodal on 08 Nov, 2017 19:59
-
This may be a dumb question from a layperson here in the peanut gallery, but I can't help wondering...
This is an excellent question. Do not feel that "you are a layperson in the peanut gallery."
There appears to be considerable work, time and expense involved in isolating these devices in order to detect tiny thrust levels. Could those resources be better spent in building a larger device designed to produces sufficient thrust to make these noise sources irrelevant?
Could I ask Monomorphic: Roughly how much have you spent (time & money) on all these activities to isolate your system, and how would that compare to trying to make a more powerful system that would be sufficiently powerful that all these noise sources would be inconsequential? Where do you think that line is?
Thanks,
-MG
This question has also been asked by aerospace engineering managers at a number of companies.
Although you will probably otherwise be given a variety of excuses like "heat concerns," "cost," "complexity," "power management" etc. I think that after decades of people working on this device, and still debating whether there is a force or not, the answer must be either because
1) the effect is not well understood and therefore people do not have a good engineering idea of how to maximize the force so that it is much higher than sources of noise (and if so this means that none of the "explanatory theories" are very useful even to scale up the effect)
or
2) the effect is not scalable. A worrisome reason for such lack of scalability is that it may be due to experimental artifacts
FACTS:
A) The Chinese EM Drive that reportedly is being tested in space looks radically different than the EM Drives tested by Shawyer, NASA Eagleworks, TU Dresden and Yang. It has a cylindrical cross-section instead of a truncated cone as tested by all those others. Instead of the truncated cone used to explain the force by several theories.
B) The "force" direction in many experiments is in the opposite direction than predicted by theories. A force at 90 degrees to the longitudinal direction, as reported now by TU Dresden is not explained by most theories (Shawyer, McCullogh, etc.) and even if somebody writes that for example the White QV theory explains forces in all directions that should be a cause of concern right there, if you think about its consequences...
If a theory cannot accurately predict ahead of time the outcome of an experiment, such a theory is of not much value...
People may reply that aerospace companies like Boeing have "gone dark" scaling it up
I don't believe it...Still looking for the flying cars and the single stage vehicle to orbit...I only have seen them in movies so far...Last year was supposed to be "the year" and suddenly now this year is almost over... -
#2672 by wicoe on 08 Nov, 2017 21:08
-
It made sense to me just fine. Maybe the difference is physics as a physicist describes it vs. experiment as an engineer does it. Both are true but sometimes are expressed in different language.
I don't think this depends on the background... if you believe this document makes sense, do you also believe that my comments below (in red) make NO sense? If yes, can you please elaborate?
-
#2673 by Ricvil on 08 Nov, 2017 21:20
-
This may be a dumb question from a layperson here in the peanut gallery, but I can't help wondering...
This is an excellent question. Do not feel that "you are you are a layperson in the peanut gallery."
There appears to be considerable work, time and expense involved in isolating these devices in order to detect tiny thrust levels. Could those resources be better spent in building a larger device designed to produces sufficient thrust to make these noise sources irrelevant?
Could I ask Monomorphic: Roughly how much have you spent (time & money) on all these activities to isolate your system, and how would that compare to trying to make a more powerful system that would be sufficiently powerful that all these noise sources would be inconsequential? Where do you think that line is?
Thanks,
-MG
This question has also been asked by aerospace engineering managers at a number of companies.
Although you will probably otherwise be given a variety of excuses like "heat concerns", "cost", "complexity", "power management" etc. I think that after decades of people working on this device, and still debating whether there is a force or not, the answer must be either because
1) the effect is not well understood and therefore people do not have a good engineering idea of how to maximize the force so that it is much higher than sources of noise (and if so this means that none of the "explanatory theories" are very useful even to scale up the effect)
or
2) the effect is not scalable. A worrisome reason for such lack of scalability is that it may be due to experimental artifacts
FACTS:
A) The Chinese EM Drive that reportedly is being tested in space looks radically different than the EM Drives tested by Shaywer, NASA Eagleworks, TU Dresden and Yang. It has a cylindrical cross-section instead of a truncated cone as tested by all those others. Instead of the truncated cone used to explain the force by several theories.
B) The "force" direction in many experiments is in the opposite direction than predicted by theories. A force at 90 degrees to the longitudinal direction, as reported now by TU Dresden is not explained by most theories (Shawyer, McCullogh, etc.) and even if somebody writes that for example the White QV theory explains forces in all directions that should be a cause of concern right there, if you think about its consequences...
If a theory cannot accurately predict ahead of time the outcome of an experiment, such a theory is of not much value...
People may reply that aerospace companies like Boeing have "gone dark" scaling it up
I don't believe it...Still looking for the flying cars and the single stage vehicle to orbit...I only have seen them in movies so far...Last year was supposed to be "the year" and suddenly now this year is almost over...
Cylindrical cross-section with what kind of termination (end shape)?
There are pictures of this particular chinese emdrive? -
#2674 by Ricvil on 08 Nov, 2017 22:38
-
I have found this
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=42978.0;attach=1446975;image
At the botton of cavity, he apparently is trying to force an artificial boundary condition with circular concentric cavities, and forcing a mode with specific nodes.
The concentric cylinders are forming coaxial structures, then he may want to force the coupling with TEM modes, except in the central one.
I can not determine what kind of mode is on the top, perhaps a TE one.
-
#2675 by Freddled Gruntbuggly on 08 Nov, 2017 22:58
-
This may be a dumb question from a layperson here in the peanut gallery, but I can't help wondering...
There appears to be considerable work, time and expense involved in isolating these devices in order to detect tiny thrust levels. Could those resources be better spent in building a larger device designed to produces sufficient thrust to make these noise sources irrelevant?
Could I ask Monomorphic: Roughly how much have you spent (time & money) on all these activities to isolate your system, and how would that compare to trying to make a more powerful system that would be sufficiently powerful that all these noise sources would be inconsequential? Where do you think that line is?
Thanks,
-MG
I believe that there were a couple of high power builds under development back in thread 9 by ARW (10kw) and CraigPichach (100kw). Unfortunately both of these users ceased posting in February of 2016. -
#2676 by spupeng7 on 09 Nov, 2017 00:20
-
The action / reaction confusion is built into the UK engineering curriculum. Please don't let it concern you as it is just a sideways technique for getting students, and everyone else, to think it through for themselves...
I have both physics and engineering backgrounds, and from neither perspective does that paper make sense. It pretty much translates to "pushing a box to the left will make the box move to the right."
Hi PN,
Please read:
http://www.emdrive.com/EmDriveForceMeasurement.pdf
I do not understand this document. The meaning is that I can not make it resonate in my brain with physics I have learned. Either it is not consistent with reality, or the physics I have learned does not describe reality, or my brain does not have the ability to relate them.
It made sense to me just fine. Maybe the difference is physics as a physicist describes it vs. experiment as an engineer does it. Both are true but sometimes are expressed in different language. -
#2677 by dustinthewind on 09 Nov, 2017 03:10
-
Hi PN,
Please read:
http://www.emdrive.com/EmDriveForceMeasurement.pdf
I do not understand this document. The meaning is that I can not make it resonate in my brain with physics I have learned. Either it is not consistent with reality, or the physics I have learned does not describe reality, or my brain does not have the ability to relate them.
It doesn't make sense to me. If it could accelerate then a force from a device that restricts it from accelerating should measure a force. Even if some gravitational field was acting on the EM drive and acted on the measuring device the measuring device still restricts the Frustum from accelerating so should measure a force.
Even in the case of 2 mirrors and both being restricted from accelerating via light bouncing between them with massive Q, one should still be able to measure a force on the mirror.
The only exception I could possibly think of might be a gravitational field that accelerates both the Frustum and a scale sitting with it. In this case the frustum and scale would both become lighter, Edit: till the scale showed weightless, in the case of lift off, they could both could ascend vertically. This is a big if and regardless the case with the force measurement device attached to a non-moving room will definitely not allow the EM drive to vertically lift off with out resistance.
I would suggest for those who have done the experiment, with the EM drive cavity on the free to rotate accelerating arm, to calculate the force necessary to accelerate their cavity at the rate it appears to. Next, make an apparatus that restricts this free acceleration of the rotating arm, can measure said force, and it should measure a force.
If the vacuum is being accelerated in the opposite direction of the EM drive to carry away some off form of momentum which acts on measurement equipment in opposition of the EM drives acceleration then this implies such measurement equipment in the vicinity of the EM drive is accelerated in the opposite direction. Such masses slightly separated from the EM drive, in the near vicinity, should then also have a measurable force acting on them in the opposite direction as the force applied to the cavity. -
#2678 by TheTraveller on 09 Nov, 2017 03:23
-
What is difficult to understand?
Two things are difficult to understand:
1. Why you continue quoting a paper that clearly illustrates that the author does not even slightly understand the concept of a force balance or F = m*a.
2. The quoted section of the paper states that the thrust goes away when error sources are eliminated. I am not sure how any conclusion can be drawn from that other than "thrust measurements are due to experimental error."
Try understanding:QuoteIn each successful case, the EmDrive force data has been superimposed on an increasing or decreasing background force, generated by the test equipment itself.
The only really good way to test an EmDrive is on a rotary test rig that allows free acceleration, well free angular acceleration. -
#2679 by meberbs on 09 Nov, 2017 03:32
-
That quote changes nothing about my previous statements, and it is a waste of time to respond to directly when you haven't considered those previous statements. Maybe you should look at wicoe's post above for further detail on how incredibly wrong that paper is.What is difficult to understand?
Two things are difficult to understand:
1. Why you continue quoting a paper that clearly illustrates that the author does not even slightly understand the concept of a force balance or F = m*a.
2. The quoted section of the paper states that the thrust goes away when error sources are eliminated. I am not sure how any conclusion can be drawn from that other than "thrust measurements are due to experimental error."
Try understanding:QuoteIn each successful case, the EmDrive force data has been superimposed on an increasing or decreasing background force, generated by the test equipment itself.
The only really good way to test an EmDrive is on a rotary test rig that allows free acceleration, well free angular acceleration.
