Author Topic: EM Drive Developments - related to space flight applications - Thread 7  (Read 1680394 times)

Offline Chrochne

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I do not understand so much optimism (from critics) here after the chinese new negative results....
Scientists are interested in finding the truth about Nature.  As such people involved in R&D understand that nullification of prior wrong results is something to be happy about, as it clears the fog of ignorance.  A researcher explores several roads to a possible destination.  When a discovery shows that one is in the wrong road, that is something to be celebrated.  It would be foolish to persist on the wrong road leading to a precipice.  The sooner that one returns to the correct road the better.

I do not understand so much optimism (from critics) ...I at least hope they will end with their harsh language towards the people that try...
I have not used name calling towards people, I only address the technical issues.  Look at your own writing: you are the one referring to people that are optimistic upon seeing Yang's latest result as "critics".  You don't need to use names to refer to people that embrace Yang's new results, but if you want to use a word, you should lead by example: you could refer to them as "scientists", or "objective people", or"people that seek the truth in Nature" instead of calling them "critics".

I was not refering to you Dr. Rodal. You are one of few who do not used any name calling. But you must admit some of the colleagues (not here on NSF thankfully) used so much harsh words that it put doubt in my mind, if those people calling themselves scientists really want to see some progress. And yes I connected that with the criticism on purpose because I see it as that.
You need those lets say little "crazy" people to put new ideas forward. You can not do without them. Look on Einstein. Many called him lunatic in his time.



Offline Rodal

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Dear NSF forum:

Just to stick my oar in briefly: this is just to point out that the new Chinese data are consistent with MiHsC.

Assuming these values: P=220W, Q=1531 (as in your wiki table) and cavity dimensions as before, MiHsC predicts 0.28 mN of thrust. Their sensitivity was quoted as 3 mN so this is below detection threshold.

Regards, Mike
Hi Mike,

Thank you for notifying me of your post at NSF, separately (there is so much activity here during the past day due to Yang's new publication, it is hard to keep up)  :)

I would appreciate it if you would refresh my mind, since I sincerely forgot.  I just quickly went over your latest article featured in MIT's Technology Review, and I don't see the name of the experimenters in the table (just letters) but I did not see a Q=1,531. (See attachment below)

http://arxiv.org/abs/1604.03449


Does this mean that you had previously not considered any of Yang's results to compare with your theoretical predictions?

Or did you previously include Yang's previous results, with Yang claiming 1 N/kW and were you showing in your table that your theory was off by orders of magnitude from predicting Yang's previous results?

Or had you compared your theory to Yang's results using a Q much larger than 1,531?  If so what Q did you use in your comparisons and where did it come from?

Didn't you compare your theory with Yang's results at one point in time in your blog (long ago)?

Concerning the dimensions and the Q you are using to arrive at these estimates, please observe:

1) the dimensions you are using were estimated by me after a lot of work, going over Yang's prior papers, her tables and equations, and using my exact solution for the mode shapes in the truncated cone.  My estimated dimensions were heavily criticized: at one point early in time a DIY builder made a truncated cone with very different dimensions based on early estimates that I considered to be very wrong.  There was a lot of controversy regarding the cone angle.  I don't think I ever got much acceptance on my dimensional estimates.  However I put those dimensions on the table because my assessment was that the dimensions that others were arguing for had a much weaker basis, and my estimate had a much stronger basis.  People arguing for other dimensions did not perform any mode shape calculations nor were they addressing the proper equations governing mode shape and frequency for a truncated cone.

2) similarly there was a lot of controversy on what was the quality of resonance Q in Yang's experiments.  I was the one that insisted on using Q=1531, because this was the only experimental value shown in her prior report.  Several people (including TheTraveller) did not approve this estimate: they thought that Yang's Q must have been closer to 100,000 than to 1,531.  They argued that the Q=1,531 was just one case and that it was not representative of the Q for her high thrust results.  In her latest results (2016) Yang provides no quality of resonance Q information.

Looking back over the fact that Yang used a connecting waveguide, just like Tajmar, I would not be surprised at Yang having a low Q because of overcoupling.  However, please take into account that TheTraveller strongly objected to Q=1,531 and actually wrote that Yang was "very clever" in getting a very high Q closer to 100,000 and that "Roger was very clever" and that Yang was a loyal disciple of Roger that would not have such a low Q.
« Last Edit: 05/02/2016 02:57 pm by Rodal »

Offline rfmwguy

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Dear NSF forum:

Just to stick my oar in briefly: this is just to point out that the new Chinese data are consistent with MiHsC.

Assuming these values: P=220W, Q=1531 (as in your wiki table) and cavity dimensions as before, MiHsC predicts 0.28 mN of thrust. Their sensitivity was quoted as 3 mN so this is below detection threshold.

Regards, Mike
Thanks for returning my invitation to rejoin the conversation Dr McCullouch...lots of theory here that we all need help with. Your MiHsC has been a good lead for us to investigate. Speaking for myself only, I continue my own 2nd generation build without a firm adherence to a particular Theory, so the more I can understand MiHsC as it relates SPECIFICALLY to my build, the better. I have read your blog and papers with a great deal of interest. I will be posting Q, frequency and power numbers on the 2nd gen soon. Welcome back!

Offline SeeShells

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Dear NSF forum:

Just to stick my oar in briefly: this is just to point out that the new Chinese data are consistent with MiHsC.

Assuming these values: P=220W, Q=1531 (as in your wiki table) and cavity dimensions as before, MiHsC predicts 0.28 mN of thrust. Their sensitivity was quoted as 3 mN so this is below detection threshold.

Regards, Mike
Thank you for posting this  :)

I would appreciate it if you would refresh my mind, since I sincerely forgot.  I just quickly went over your latest article featured in MIT's Technology Review, and I don't see the name of the experimenters in the table (just letters) but I did not see a Q=1,500.


Does this mean that you had previously not considered any of Yang's results to compare with your theoretical predictions?

Or did you previously include Yang's previous results, with Yang claiming 1 mN/kW and were you showing in your table that your theory was off by orders of magnitude from predicting Yang's previous results?

Concerning the dimensions and the Q you are using to arrive at these estimates, please observe:

1) the dimensions you are using were estimated by me after a lot of work, going over Yang's prior papers, her tables and equations, and using my exact solution for the mode shapes in the truncated cone.  My estimated dimensions were heavily criticized: at one point early in time a DIY builder made a truncated cone with very different dimensions based on early estimates that I considered to be very wrong.  There was a lot of controversy regarding the cone angle.  I don't think I ever got much acceptance on my dimensional estimates.  However I put those dimensions on the table because my assessment was that the dimensions that others were arguing for had a much weaker basis, and my estimate had a much stronger basis.  People arguing for other dimensions did not perform any mode shape calculations nor were they addressing the proper equations governing mode shape and frequency for a truncated cone.

2) similarly there was a lot of controversy on what was the quality of resonance Q in Yang's experiments.  I was the one that insisted on using Q=1531, because this was the only experimental value shown in her prior report.  Several people (including TheTraveller) did not approve this estimate: they thought that Yang's Q must have been closer to 100,000 than to 1,500.  In her latest results (2016) Yang provides no quality of resonance Q information.

Listing the differences between the two tests highlights questions that still need to be answered. I don't consider Yang's a dead end test but good data to use, and as I've said before, there is no bad data.

1. What measured differences will be seen in a test rig that can do both teeter todder balance beam and torsional pendulum, when Lorentz forces and thermals are taken into account and mapped.

2. What differences will be seen with a clean narrow band RF signal versus a AM modulated broad band width? Would a controlled Pulse Width Modulated duty cycle on a 1 MHz clean magnetron find a sweet spot in a thrust component and work better than the chaotic actions of a microwave oven power supply?
http://www.gigatronics.com/practical-guide-microwave-switch-selection

3. Using and profiling different inserts or combinations of inserts in the cavity show better effects.

4. Will two antennas into the cavity work better than one? Will shifting the phase of one with respect to the other help or hinder a thrust component?

They're many different options and paths to check and these are just a couple on the list.

Shell

PS: I would like to thank Yang for taking the time and having the integrity and honor to publish her new results.

« Last Edit: 05/02/2016 01:51 pm by SeeShells »

Offline MikeMcCulloch

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Dear NSF forum:

Just to stick my oar in briefly: this is just to point out that the new Chinese data are consistent with MiHsC.

Assuming these values: P=220W, Q=1531 (as in your wiki table) and cavity dimensions as before, MiHsC predicts 0.28 mN of thrust. Their sensitivity was quoted as 3 mN so this is below detection threshold.

Regards, Mike
Hi Mike,

Thank you for posting this  :)

I would appreciate it if you would refresh my mind, since I sincerely forgot.  I just quickly went over your latest article featured in MIT's Technology Review, and I don't see the name of the experimenters in the table (just letters) but I did not see a Q=1,531. (See attachment below)

http://arxiv.org/abs/1604.03449


Does this mean that you had previously not considered any of Yang's results to compare with your theoretical predictions?

Or did you previously include Yang's previous results, with Yang claiming 1 mN/kW and were you showing in your table that your theory was off by orders of magnitude from predicting Yang's previous results?

Or had you compared your theory to Yang's results using a Q much larger than 1,531?  If so what Q did you use in your comparisons and where did it come from?

Concerning the dimensions and the Q you are using to arrive at these estimates, please observe:

1) the dimensions you are using were estimated by me after a lot of work, going over Yang's prior papers, her tables and equations, and using my exact solution for the mode shapes in the truncated cone.  My estimated dimensions were heavily criticized: at one point early in time a DIY builder made a truncated cone with very different dimensions based on early estimates that I considered to be very wrong.  There was a lot of controversy regarding the cone angle.  I don't think I ever got much acceptance on my dimensional estimates.  However I put those dimensions on the table because my assessment was that the dimensions that others were arguing for had a much weaker basis, and my estimate had a much stronger basis.  People arguing for other dimensions did not perform any mode shape calculations nor were they addressing the proper equations governing mode shape and frequency for a truncated cone.

2) similarly there was a lot of controversy on what was the quality of resonance Q in Yang's experiments.  I was the one that insisted on using Q=1531, because this was the only experimental value shown in her prior report.  Several people (including TheTraveller) did not approve this estimate: they thought that Yang's Q must have been closer to 100,000 than to 1,531.  They argued that the Q=1,531 was just one case and that it was not representative of the Q for her high thrust results.  In her latest results (2016) Yang provides no quality of resonance Q information.

Looking back over the fact that Yang used a connecting waveguide, just like Tajmar, I would not be surprised at Yang having a low Q because of overcoupling.  However, please take into account that TheTraveller strongly objected to Q=1,531 and actually wrote that Yang was "very clever" in getting a very high Q closer to 100,000 and that "Roger was very clever" and that Yang was a loyal disciple of Roger that would not have such a low Q.

On a blog last year I compared the Chinese results initially using a high Q in my calculations (32,000 - 50,000). My source on those values was NSF. Then, someone on the forum discovered that the Chinese were using a different definition of Q to all the other experiments and so their 'real' Q was unknown. So, I could not use the Chinese results for my paper (see my paper, 2nd paragraph).

Regarding the new Chinese results I naturally went to the emdrive wiki table and found your estimate of Q (1531). Obviously, to be useful as a test, the new result's Q needs to be known. I'll email Dr Yang (I did last year too, but received no reply).

Offline Rodal

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...

On a blog last year I compared the Chinese results initially using a high Q in my calculations (32,000 - 50,000). My source on those values was NSF. Then, someone on the forum discovered that the Chinese were using a different definition of Q to all the other experiments and so their 'real' Q was unknown. So, I could not use the Chinese results for my paper (see my paper, 2nd paragraph).

Regarding the new Chinese results I naturally went to the emdrive wiki table and found your estimate of Q (1531). Obviously, to be useful as a test, the new result's Q needs to be known. I'll email Dr Yang (I did last year too, but received no reply).
OK thanks for the clarification. 

The Q=1531 is not an estimate, but it is the actual experimental value in Yang's papers.  The controversy about it is not whether she ever measured Q=1531, she did, there is no doubt about it.  The controversy is whether this experimental value corresponded to the same experiments where she claimed the now falsified value of 1 N/kW

The controversy involves the following:

1) Yang calculated (using a computer program, based on calculated skin depth, and conductivity values for brass material, and the theoretical dependence of Q on mode shape because of the dependence of the energy on the volume and the surface area) much higher Q, and published those higher Q's in an earlier paper.  I argued that those calculated values of Q were irrelevant, what matters is the actual measured Q.  (Just for comparison, there are multiple posts at NSF EM Drive thread of people using Meep to incorrectly output Q's of millions, which also should not be taken as realistic).

2) Her experimental paper showed a very low experimental value Q=1531 when using the same definition for Q as used by other experimenters, the standard definition:



Q = 2.45 GHz /0.0016 GHz  = 1531  (see plot below)

3) There is no way to justify Yang's previous claimed experimental results using Shawyer's theory using Q=1,531.  Therefore TheTraveller stated that her Q must have been closer to 100,000, and that her published value of Q=1,531 must have referred to a non-representative experiment.  I presume that also, your theory would not be able to predict her previously claimed (now falsified) 1 N/kW if using Q=1,531

4) It is great that NSF keeps old posts. One can then verify how TheTraveller and others were insisting that it was not possible for Yang's Q to have been 1531 (just like people insisted that Yang's claimed results of 1 N/kW were genuine). It is interesting that after all this, if it turns out that her published value of Q=1531 may turn out to be correct, as well as my estimated dimensions for Yang's frustum may turn out to be correct, and that the value of 1 N/kW shown to be an experimental artifact, nullified when using batteries and a torsional pendulum.  It is indeed interesting if your theory is shown to predict a much smaller value than 1 N/kW when using the value of Q=1531.



5) One must ask oneself why is it that people were more willing to believe the claimed 1 N/kW force/InputPower instead of acknowledging that her Q was 1531 ?  Are similar mistakes made in assessing other EM Drive data?
« Last Edit: 05/02/2016 03:11 pm by Rodal »

Offline MikeMcCulloch

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Indeed, using Q=1531, I would be unable to predict her now-falsified earlier result, but her results are now more in line with others and with MiHsC. I wonder why her results were so different before: an artifact? (I see you also suspect an artifact).
« Last Edit: 05/02/2016 02:57 pm by MikeMcCulloch »

Offline Rodal

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Indeed, using Q=1531, I would be unable to predict her now-falsified earlier result, but her results are now more in line with others and with MiHsC. I wonder why her results were so different before: an artifact? (I see you also suspect an artifact).

Since your theory is linear with Q and InputPower, and you calculate 0.28 mN at 220 Watts, you are calculating only

force/InputPower=0.28 mN/(1000 mN/N)/(220W)/(1000W/kW)= 0.00127 N/kW

for Q=1531

therefore to match her previous claims of 1 N/kW, your theory would need a Q of

Q=(1/ 0.00127)*1531
  =1.2*10^6

a Q over a million, which is impossible unless one has superconductivity

Your theory would need a Q 800 times larger.  That is 3 orders of magnitude larger.

That is how different were her previous claims of 1 N/kW (a factor of 800 times), now falsified with her courageous show of integrity, which she should be applauded for.

The main problem with her prior experiments was the use of a power source using power cables instead of using self-integrated batteries.  The other problem was her testing instrument.

Experimental results using teeter-totters, scales and other faulty instruments are very questionable

The instrument of choice in over 50 years in Aerospace R&D for micro-thrusters has been the torsional pendulum.  NASA, Tajmar (only in vacuum) have used torsional pendulums.   Shawyer has never reported a single test in a torsional pendulum.

It seems that people that report tests not using torsional pendulums are not aware of the many experimental reports for micro-thrusters at MIT Aeronautics and Astronautics Department.

The only experimenters that have reported using batteries to test the EM Drive (prior to Yang's latest results) are the Aachen Germany Hackaway team (Baby EM Drive).

Cannae is reporting now having a torsional pendulum and batteries, and I look forward to their future results.

I also look forward to NASA running tests with the John Hopkins Cavendish torsional pendulum and batteries.

This is what it would take to verify EM Drive thrust (short of experimenting in space):

1) Torsional pendulum

2) Using power provided by batteries self-integrated in the moving platform

3) Vacuum chamber


Tests that don't fulfill all 3 requirements above will just be adding to the noise that has been criticized by Prof. Baez, by Prof. Carroll and others.

For the EM Drive to be accepted we need experimenters to address all 3 items above.  (*)They have been known for a long time: radiation pressure has been a problem to measure (unless one uses vacuum chambers) since the 19th century.  It has been known for 50 year of Aerospace R&D that micro-thrusters should be tested in torsional pendulums.  The problems with Lorentz forces due to cables and thermal expansion, and conservation of energy for electromagnetic propellant-less thrusters have also been known for a long time.

___________

(*) Not a comment on DIY problems.  I am only interested in the subject of this thread EM Drive Developments - related to space flight application.  I am only interested on whether the EM Drive can be used for spaceflight applications.    To address spaceflight applications all 3 considerations need to be met.
« Last Edit: 05/02/2016 03:36 pm by Rodal »

Offline tchernik

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Wow, so many things happening in a little time.

And at least one of them seems to be bad news (at least for people like me that would like if this was true). That is, Yang basically recanted her own previously astounding results.

If I'm honest, that result certainly dispirited me a little bit about the Emdrive as well. And probably it did the same for other people doing their own experiments.

Nevertheless, let's remember that having more knowledge is always better, not worse. If the tests were nullified, so be it. Don't count it as a positive with its given power, frequency, geometry and measure instrument resolution.

For me, this means the remaining Emdrive experiments seem to be showing small thrust in torsion balance tests in a vacuum, at the tested energies, frequencies, geometries and instrument resolutions.

NASA EW and UT Dresden's experiments are better in their setup (AFAIK) and they are still standing. Unless recanted, which I think they would if their authors figured out they were actual measurement errors as Yang's.
« Last Edit: 05/02/2016 03:36 pm by tchernik »

Offline rfmwguy

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It was my first reaction as well, however once some of the papers content began to appear, I realized their experiment had set a very high goal...3 mN minimum resolution/accuracy and a little over 200 watts RF. This is far above other tests. My own test observations were about 0.1 mN at about 900 watts. Granted, it was with a low Q device, not tuned for perfect resonance.

That being said, 3 mN is a robust force to measure at 220W. Wish their torsion wire test stand could resolve 100 μN, they might have observed something. Note per the emdrive.wiki page, they were claiming 160 and 170 mN last time. Probably why they felt 3 mN was sufficient to validate.
« Last Edit: 05/02/2016 04:03 pm by rfmwguy »

Offline Rodal

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It was my first reaction as well, however once some of the papers content began to appear, I realized their experiment had set a very high goal...3 mN minimum reolution/accuracy and a little over 200 watts RF. This is far above other tests. My own test observations were about 0.1 mN at about 900 watts. Granted, it was with a low Q device, not tuned for perfect resonance.

That being said, 3 mN is a robust force to measure at 220W. Wish their torsion wire test stand could resolve 100 μN, they might have observed something. Note per the emdrive.wiki page, they were claiming 160 and 170 mN last time. Probably why they felt 3 mN was sufficient to validate.
No, not 3 mN, please read their report and posts from TellMeAgain, look at what they measured in 20 tests with batteries, 0.7mN (80%) @ 220Watts = 3.18 mN/kW (the force is 0.7 mN (80%)!!!!  ):



As all readers can see from the plot, she actually measured less than 0.7 mN.

You appear to me misinterpreting the meaning of her statistical analysis !!! .

You are confusing measured force in an experiment with confidence estimates given uncertainty.
« Last Edit: 05/02/2016 04:25 pm by Rodal »

Offline Monomorphic

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And at least one of them seems to be bad news (at least for people like me that would like if this was true). That is, Yang basically recanted her own previously astounding results.

Actually this is good news. As an outlier, Yang's results were always suspect. It's good that she has recanted.

Does anyone else find it odd that no exact frustum dimensions are shared and there are zero real images of the build?

Offline Rodal

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And at least one of them seems to be bad news (at least for people like me that would like if this was true). That is, Yang basically recanted her own previously astounding results.

Actually this is good news. As an outlier, Yang's results were always suspect. It's good that she has recanted.

Does anyone else find it odd that no exact frustum dimensions are shared and there are zero real images of the build?

I fully agree  :)

Offline rfmwguy

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Indeed, using Q=1531, I would be unable to predict her now-falsified earlier result, but her results are now more in line with others and with MiHsC. I wonder why her results were so different before: an artifact? (I see you also suspect an artifact).

(snip)

This is what it would take to verify EM Drive thrust (short of experimenting in space):

1) Torsional pendulum

2) Using power provided by batteries self-integrated in the moving platform

3) Vacuum chamber


Tests that don't fulfill all 3 requirements above will just be adding to the noise that has been criticized by Prof. Baez, by Prof. Carroll and others.

For the EM Drive to be accepted we need experimenters to address all 3 items above.  (*)They have been known for a long time: radiation pressure has been a problem to measure (unless one uses vacuum chambers) since the 19th century.  It has been known for 50 year of Aerospace R&D that micro-thrusters should be tested in torsional pendulums.  The problems with Lorentz forces due to cables and thermal expansion, and conservation of energy for electromagnetic propellant-less thrusters have also been known for a long time.

___________

(*) Not a comment on DIY problems.  I am only interested in the subject of this thread EM Drive Developments - related to space flight application.  I am only interested on whether the EM Drive can be used for spaceflight applications.    To address spaceflight applications all 3 considerations need to be met.
I think we need to clarify for our readership, that you are referring to Space Qualification testing, which is normally done only after other ground based tests are conducted.

We are now in an early TRL stage, or proof of concept if you will. It is far too early to insist on S-Level testing, nor is it correct to infer that ground level testing is not relevant.

No DIY nor few universities have S-Level capabilities, yet universities continue to design and test cubesats for S-Level qualification testing elsewhere.

So all of what you mention is relevant for S-Level tests, not for observational or proof of concept testing.

A good paper to help the readership understand the difference between Engineering Units and Spaceflight Units and some of the S-Level tests that labs do is here: http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1491&context=theses

Not this one describes only shock & vibration testing. Chances are this is a powered test with umbilicals and not in a vacuum.
« Last Edit: 05/02/2016 04:21 pm by rfmwguy »

Offline Rodal

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Indeed, using Q=1531, I would be unable to predict her now-falsified earlier result, but her results are now more in line with others and with MiHsC. I wonder why her results were so different before: an artifact? (I see you also suspect an artifact).

(snip)

This is what it would take to verify EM Drive thrust (short of experimenting in space):

1) Torsional pendulum

2) Using power provided by batteries self-integrated in the moving platform

3) Vacuum chamber


Tests that don't fulfill all 3 requirements above will just be adding to the noise that has been criticized by Prof. Baez, by Prof. Carroll and others.

For the EM Drive to be accepted we need experimenters to address all 3 items above.  (*)They have been known for a long time: radiation pressure has been a problem to measure (unless one uses vacuum chambers) since the 19th century.  It has been known for 50 year of Aerospace R&D that micro-thrusters should be tested in torsional pendulums.  The problems with Lorentz forces due to cables and thermal expansion, and conservation of energy for electromagnetic propellant-less thrusters have also been known for a long time.

___________

(*) Not a comment on DIY problems.  I am only interested in the subject of this thread EM Drive Developments - related to space flight application.  I am only interested on whether the EM Drive can be used for spaceflight applications.    To address spaceflight applications all 3 considerations need to be met.
I think we need to clarify for our readership, that you are referring to Space Qualification testing, which is normally done only after other ground based tests are conducted.

We are now in an early TRL stage, or proof of concept if you will. It is far too early to insist on S-Level testing, nor is it correct to infer that ground level testing is not relevant.

No DIY nor few universities have S-Level capabilities, yet universities continue to design and test cubesats for S-Level qualification testing elsewhere.

So all of what you mention is relevant for S-Level tests, not for observational or proof of concept testing.
No, I am not referring to Space Qualification Testing.  I am referring to testing that makes sense to corroborate the EM Drive claims, at this point in time, as per NASA, Boeing, Lockheed-Martin, MIT, CalTech, Stanford, ESA, etc.

I am referring to what would be acceptable if somebody would request funding for such an experiment to be conducted at a University (graduate program) or at a corporate or public R&D, or at the US Air Force.

MIT has reports discussing the need for torsional pendulum for micro-thruster R&D dating back to several years ago.

People have known about the problems associated with measuring radiation pressure since the 19 th century.

I was certainly not addressing anything concerning your particular building DIY activities, I am only interested in EM Drive Developments - related to space flight applications and addressing what is necessary for proving whether the EM Drive can be used or not for spaceflight applications.

« Last Edit: 05/02/2016 04:33 pm by Rodal »

Offline rfmwguy

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We will have to agree to disagree. What you mentioned is for space qualification, not for an engineering or proof of concept unit. Granted, this opinion is based on my direct work experience at S-Level...which always includes:

1) (impact) Shock & Vibration
2) Fine Leak (for overall assembly)
3) (Other things I've forgotten over the years)

Vaxheadroom is an expert on this as it is his vocation. In my conversations with him, he gave me a lot more of the current reqs...since I've been out of it for 15+ years. Much has changed and I am not an expert on todays reqs. Vax is...

DIYers are performing Engineering Unit (proof of concept) tests with the goal of spaceflight, and not necessarily just for a peer-reviewed paper. A lot can be learned from ground-based tests...such as, is it worth trying to engineer for the next level of testing? No DIYer is there yet AFAIK.

Offline SeeShells

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Indeed, using Q=1531, I would be unable to predict her now-falsified earlier result, but her results are now more in line with others and with MiHsC. I wonder why her results were so different before: an artifact? (I see you also suspect an artifact).

(snip)

This is what it would take to verify EM Drive thrust (short of experimenting in space):

1) Torsional pendulum

2) Using power provided by batteries self-integrated in the moving platform

3) Vacuum chamber


Tests that don't fulfill all 3 requirements above will just be adding to the noise that has been criticized by Prof. Baez, by Prof. Carroll and others.

For the EM Drive to be accepted we need experimenters to address all 3 items above.  (*)They have been known for a long time: radiation pressure has been a problem to measure (unless one uses vacuum chambers) since the 19th century.  It has been known for 50 year of Aerospace R&D that micro-thrusters should be tested in torsional pendulums.  The problems with Lorentz forces due to cables and thermal expansion, and conservation of energy for electromagnetic propellant-less thrusters have also been known for a long time.

___________

(*) Not a comment on DIY problems.  I am only interested in the subject of this thread EM Drive Developments - related to space flight application.  I am only interested on whether the EM Drive can be used for spaceflight applications.    To address spaceflight applications all 3 considerations need to be met.
I think we need to clarify for our readership, that you are referring to Space Qualification testing, which is normally done only after other ground based tests are conducted.

We are now in an early TRL stage, or proof of concept if you will. It is far too early to insist on S-Level testing, nor is it correct to infer that ground level testing is not relevant.

No DIY nor few universities have S-Level capabilities, yet universities continue to design and test cubesats for S-Level qualification testing elsewhere.

So all of what you mention is relevant for S-Level tests, not for observational or proof of concept testing.

A good paper to help the readership understand the difference between Engineering Units and Spaceflight Units and some of the S-Level tests that labs do is here: http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1491&context=theses

Not this one describes only shock & vibration testing. Chances are this is a powered test with umbilicals and not in a vacuum.

I couldn't agree more Dave. Small shop testing has it's limits with testing, budgets and cannot be expected to do level testing in vacuum unless funded to be able to do so. All of the builders here have pushed their test beds and drive designs far past where we were even 6 months ago.

Back to work for me.

Shell

Added: My concern if someone were to invest the large sums needed and test for Space Based systems. What would happen if their best guess at a configuration didn't work? Right now we're not certain which RF source works best wide band AM modulated magnetron or a single narrow band source, or even the mode of operation TE or TEM or TE or if it takes 2 or more modes of TE or TE and TM, or if a dielectric insert works as thought. Fundamental fact finding first and then build up.
« Last Edit: 05/02/2016 04:45 pm by SeeShells »

Offline zen-in

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It was my first reaction as well, however once some of the papers content began to appear, I realized their experiment had set a very high goal...3 mN minimum reolution/accuracy and a little over 200 watts RF. This is far above other tests. My own test observations were about 0.1 mN at about 900 watts. Granted, it was with a low Q device, not tuned for perfect resonance.

That being said, 3 mN is a robust force to measure at 220W. Wish their torsion wire test stand could resolve 100 μN, they might have observed something. Note per the emdrive.wiki page, they were claiming 160 and 170 mN last time. Probably why they felt 3 mN was sufficient to validate.
No, not 3 mN, please read their report and posts from TellMeAgain, look at what they measured in 20 tests with batteries, 0.7mN (80%) @ 220Watts = 3.18 mN/kW (the force is 0.7 mN (80%)!!!!  ):



As all readers can see from the plot, she actually measured less than 0.7 mN.

You appear to me misinterpreting the meaning of her statistical analysis !!! .

You are confusing measured force in an experiment with confidence estimates given uncertainty.

It is to her credit that Yang has disclosed these new experiments.     The 20 experimental results shown in the graph don't look to me like convincing argument for any force.   I don't see a need for fitting a curve to these data.    If all 20 force measurements are averaged the result is -74 microNewtons.   If the outliers are thrown out first (any force measurement greater than .4 mN or less than -.4 mN) the average becomes -30 microNewtons.   While these calculations are just estimates themselves they do show a trend approaching zero.

Offline Rodal

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...I couldn't agree more Dave. Small shop testing has it's limits with testing, budgets and cannot be expected to do level testing in vacuum unless funded to be able to do so. All of the builders here have pushed their test beds and drive designs far past where we were even 6 months ago.

Back to work for me.

Shell
We also have Mr. Li  (TellMeAgain) as a builder that proved that spending $7 on a piano wire, he put together a test using a torsional pendulum to address Lorentz forces.  Much better design that a Teeter_Totter device, as has been known in Aerospace R&D for micro-thrusters over 50 years. And as has been known for hundreds of years ever since Cavendish tests to measure G.

And as it was known from Brito, Marini and Galian's previous falsification of a propellant-less thruster.

Torsional Pendulum --> much better instrument to measure micro-thrust for spaceflight applications than a teeter-totter

BOTTOM LINE: the miss-selection of a teeter-totter over a torsional pendulum was not governed by budget limitations
« Last Edit: 05/02/2016 05:02 pm by Rodal »

Offline Chrochne

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It was my first reaction as well, however once some of the papers content began to appear, I realized their experiment had set a very high goal...3 mN minimum reolution/accuracy and a little over 200 watts RF. This is far above other tests. My own test observations were about 0.1 mN at about 900 watts. Granted, it was with a low Q device, not tuned for perfect resonance.

That being said, 3 mN is a robust force to measure at 220W. Wish their torsion wire test stand could resolve 100 μN, they might have observed something. Note per the emdrive.wiki page, they were claiming 160 and 170 mN last time. Probably why they felt 3 mN was sufficient to validate.
No, not 3 mN, please read their report and posts from TellMeAgain, look at what they measured in 20 tests with batteries, 0.7mN (80%) @ 220Watts = 3.18 mN/kW (the force is 0.7 mN (80%)!!!!  ):



As all readers can see from the plot, she actually measured less than 0.7 mN.

You appear to me misinterpreting the meaning of her statistical analysis !!! .

You are confusing measured force in an experiment with confidence estimates given uncertainty.

It is to her credit that Yang has disclosed these new experiments.     The 20 experimental results shown in the graph don't look to me like convincing argument for any force.   I don't see a need for fitting a curve to these data.    If all 20 force measurements are averaged the result is -74 microNewtons.   If the outliers are thrown out first (any force measurement greater than .4 mN or less than -.4 mN) the average becomes -30 microNewtons.   While these calculations are just estimates themselves they do show a trend approaching zero.

Yes I admit you were right Zen-In from the begining of this thing. That makes a fool of me to believe in such device and advance of the humanity. Guess I need to chill for a while.

So much hope destroyed.. lets keep to exploding engines.. Just hope it will not cost us of too much lives of astronauts

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