Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797723 times)

Offline TheTraveller

Shawyer has updated his device Force generation and direction summary to include the Tajmar results as attached.

That makes 8 devices, tested in 4 countries and 5 labs.
« Last Edit: 07/29/2015 12:12 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline birchoff

  • Full Member
  • **
  • Posts: 267
  • United States
  • Liked: 122
  • Likes Given: 95
Shawyer has updated his device Force generation and direction summary to include the Tajmar results as attached.

That makes 8 devices, tested in 4 countries and 5 labs.

Why is shawyer's updated results saying that dresden measured 0.164mN of trust when the report said 0.020mN

Offline TheTraveller

Shawyer has updated his device Force generation and direction summary to include the Tajmar results as attached.

That makes 8 devices, tested in 4 countries and 5 labs.

Why is shawyer's updated results saying that dresden measured 0.164mN of trust when the report said 0.020mN

Is specific Force / kW. So 164uN/kW.

The vacuum Force can be thrown, IMO, away as the cavity insides were oxidised and there were numerous issues with the vac test rig that need sorted.

Here are averaged the atmo Force measurements from 38 test runs.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline Flyby

  • Full Member
  • ***
  • Posts: 382
  • Belgium
  • Liked: 447
  • Likes Given: 46
Email from Roger Shawyer just arrived giving author access to his official peer reviewed paper and a video presentation on the right side which mentions the Tajmar results.

Back from holiday...   fwew... had a lot of catching up to do...

Had a quick diagonal look at the presented document and find it disappointing...
It bothers me that all the numbers are theoretical calculations and future projections. I could not spot any real hard data from a functional second generation device.

It is all too easy to make linear extrapolations based upon (questionable?) theoretical contemplations, where as most engineers inhere know all too well that there is a huge gap between a project build on paper and an actual build one, that functions as predicted/hoped.
There are always a lot of unforeseen difficulties that bog down the estimated performances.

So really, until i see some REAL test data, I have a hard time believing all the air castles we're promised.
A clearly functional prototype is what's needed to give the...euh... EM drive.... the credibility it so badly needs...

The Tajmar papers are not conclusive enough to either validate or disprove the EMdrive.
Depending on how you look at that fact, it is either encouraging or disappointing. Fact remains that no real advance has been made... sadly...

To Seeshell: sorry to read about the loss of the person you loved so much... :(

To dr.Rodal: I'll try to finish up the "guesstimate" drawing of the Yang frustum+waveguide, once I've plowed through the piles of work that has accumulated here, during my absence...
Is there any additional measurement/drawing that can be done on the Tajmar frustum? (noticed some issues on the dimensions)
« Last Edit: 07/29/2015 08:19 PM by Flyby »

Offline glennfish

  • Full Member
  • ***
  • Posts: 387
  • Liked: 281
  • Likes Given: 168
Re: Tajmar's paper

See this study:  http://aml.jlu.edu.cn/Htdocs/bd/jq/article/MMTA061.pdf

Note the sensitivity of the scale under Experimental Methods.

Also consider the surface area of an arbitrary cross section of the upper and lower portions of the cone.

Also note that Tajmar reports a reduction in Q due to oxidation.

The cited study notes that oxidation rates increase with temperature.

The cone heats up, oxidation increases.  The cone cools down, oxidation decreases.

Oxidation results in weight gains.

The weight gains would be greater at the wide portion of the cone, than the narrow portion.  It's just possible that the force vectors are a result of differential oxidation weight changes  across the length of the cone, which would be measurable over time at the scale measured in his paper.

However in the vacuum reported, there's only about 5 micrograms per cubic meter of potential oxidant.

So.... just some speculation
« Last Edit: 07/30/2015 01:23 AM by glennfish »

Online Rodal

  • Senior Member
  • *****
  • Posts: 5834
  • USA
  • Liked: 5901
  • Likes Given: 5249
Re: Tajmar's paper

See this study:  http://aml.jlu.edu.cn/Htdocs/bd/jq/article/MMTA061.pdf

Note the sensitivity of the scale under Experimental Methods.

Also consider the surface area of an arbitrary cross section of the upper and lower portions of the cone.

Also note that Tajmar reports a reduction in Q due to oxidation.

Oxidation results in weight gains.

The weight gains would be greater at the wide portion of the cone, than the narrow portion.  It's just possible that the force vectors are a result of differential oxidation weight changes  across the length of the cone, which would be measurable over time at the scale measured in his paper.

However in the vacuum reported, there's only about 5 micrograms per cubic meter of potential oxidant.

So.... just some speculation

WELCOME to the thread.  Thank you for making these great points.

Online Rodal

  • Senior Member
  • *****
  • Posts: 5834
  • USA
  • Liked: 5901
  • Likes Given: 5249
Shawyer has updated his device Force generation and direction summary to include the Tajmar results as attached.

That makes 8 devices, tested in 4 countries and 5 labs.

In that chart



Shawyer  shows the "Force Direction" in the TU Dresden (Tajmar et al) experiments to be in the opposite direction as the "Force Direction" in the NASA experiments.

NASA force is shown as "Thrust" and pointing from small end to large end.  But Paul March emphasized that the force they measured at NASA was in the opposite direction, from big base to small base.  Both the force that NASA reported and the displacement motion that NASA measured were pointing towards the small base, as Paul March said explicitly.  Why does Shaywer show the NASA force to be in the direction of the Big Base, which is the complete opposite of what Paul March reported? 

Please elaborate as to where is the evidence that the force direction is in opposite directions between NASA and Dresden.

Thanks
« Last Edit: 07/29/2015 01:13 PM by Rodal »

Offline madsci

  • Member
  • Posts: 22
  • Liked: 4
  • Likes Given: 3
By the way, here you can find legit non-paywalled links to the papers presented by Martin Tajmar in PDF format at AIAA 2015, among others.

http://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/rfs/forschung/folder.2007-08-21.5231434330/ag_raumfahrtantriebe/breakthrough_propulsion_physics

P.S.

I don't know how to make a correct hyperlink. Hopefully this doesn't break the page format.

  Thanks for the link, it works.

Offline TheTraveller

Looking at the Up and Down Force curve chart I created from the Tajmar summary it suggests:

Peak powered Up force was 620uN
Peak powered Down force was -391uN.
From that Up buoyancy Force was 115uN.
Adjusted Up and Down peak powered Forces are then 505uN at 660W (VSWR 1.622:1) or 0.765mN/kW.

Further adjusting the specific Force for Q 48.8 to Q 50,000 yields 784mN/kW which brings the specific Force into the range I would expect.

« Last Edit: 07/29/2015 01:21 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

Shawyer has updated his device Force generation and direction summary to include the Tajmar results as attached.

That makes 8 devices, tested in 4 countries and 5 labs.

In that chart



Shawyer  shows the "Force Direction" in the TU Dresden (Tajmar et al) experiments to be in the opposite direction as the "Force Direction" in the NASA experiments.

NASA force is shown as "Thrust" and pointing from small end to large end.  But Paul March emphasized that the force they measured at NASA was in the opposite direction, from big base to small base.  Both the force that NASA reported and the displacement motion that NASA measured were pointing towards the small base, as Paul March said explicitly.  Why does Shaywer show the NASA force to be in the direction of the Big Base, which is the complete opposite of what Paul March reported? 

Please elaborate as to where is the evidence that the force direction is in opposite directions between NASA and Dresden.

Thanks

Will ask Paul and report back.

I should add that with the dielectric in the EW frustum, it may be possible, depending on mode and how vibration kicks off MOTOR mode and how well tuned is the frequency to the centre of the frustum bandwidth, to get Force in either directing being toward the big end if dielectric triggered or toward to small end if the non dielectric Forces win.

BTW Dr. Rodal are you running LANL's SuperFish to do your frustum calcs? It is built to do resonant cavity designs. Asked because SuperFish does gen cavity Q and you started giving out cavity Q as well as resonance. Good to see our 2 different resonance and mode analysis methods are predicting the same resonance frequency and mode, which is good news for DIY builders. ;)
« Last Edit: 07/29/2015 01:31 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline rfmwguy

  • EmDrive Builder (retired)
  • Senior Member
  • *****
  • Posts: 2165
  • Liked: 2681
  • Likes Given: 1124
Thanks to Dr Tajmar for his paper and willingness to dip into a controversial area. I venture to say that those playing it safe, sitting back and not piecing something together should give him some props for outside the box thinking.

That being said:

Size matters - After reading the paper and about anything else I can find, his frustum design and launcher probably should have been more conventional (upsized) so we can compare relative apples to relative apples. While the miniaturized version is interesting, it appears we may need to work in a larger scale, at least at 2.45 GHz.

Oxidation - Yes, I can relate to this. Before I began thermal testing, I removed LOTS of black copper oxide which had been deposited at room temperature storage. Copper flashing on RF modules are quickly covered with silver or nickel, to prevent this. It will add weight and more importantly, degrade performance. I suggest all oxides be removed prior to any electrical testing.

Adhesives - Nope, not using any. Solder only with excess flux removed. Outgassing can happen with them.

Dissimilar metals - Normally do not use different metals for supression of intermodulation, but also for potential buildup of galvanic corrosion over time.

Balance beam - Respectfully disagree with this method being useful. Sticking with it for now.




Online Rodal

  • Senior Member
  • *****
  • Posts: 5834
  • USA
  • Liked: 5901
  • Likes Given: 5249
...
BTW Dr. Rodal are you running LANL's SuperFish to do your frustum calcs? It is built to do resonant cavity designs. Asked because SuperFish does gen cavity Q and you started giving out cavity Q as well as resonance. Good to see our 2 different resonance and mode analysis methods are predicting the same resonance frequency and mode, which is good news for DIY builders. ;)
I am NOT running Superfish or any other "black box" code.
I only run my own codes.  As previously stated using Wolfram Mathematica to write my own software.  The natural frequency, and Q calculations are based on an exact solution using Associated Legendre and Spherical Bessel Functions.  Only recently I wrote the code routine to calculate the maximum possible Q value based on material resistivity and the exact solution for the electromagnetic fields.
Some time ago I also wrote a subroutine to calculate the best equivalent solution for flat faces based on the spherical face exact solution, so whenever calculating flat faces I base it on that.

Making substantial progress in calculating a force: it is definitely pointing towards the small end, but my calculated force is substantially smaller than what others claim.  Not ready for publication yet.
« Last Edit: 07/29/2015 01:53 PM by Rodal »

Offline sghill

  • Full Member
  • ****
  • Posts: 1298
  • United States
  • Liked: 1427
  • Likes Given: 1969
Both the force that NASA reported and the displacement motion that NASA measured were pointing towards the small base, as Paul March said explicitly.  Why does Shaywer show the NASA force to be in the direction of the Big Base, which is the complete opposite of what Paul March reported?

The AA batteries were in backwards? :)
Bring the thunder Elon!

Online Rodal

  • Senior Member
  • *****
  • Posts: 5834
  • USA
  • Liked: 5901
  • Likes Given: 5249
Both the force that NASA reported and the displacement motion that NASA measured were pointing towards the small base, as Paul March said explicitly.  Why does Shaywer show the NASA force to be in the direction of the Big Base, which is the complete opposite of what Paul March reported?

The AA batteries were in backwards? :)

I don't understand why TheTraveller is going to be asking Paul March,

...Will ask Paul and report back....

 when Paul March has clearly stated that the force he reported and the displacement are both pointing towards the small base.  The question is why Roger Shawyer reporting the opposite direction for the force that NASA reported.  How can Roger Shawyer know more and better about what NASA measured than NASA themselves ???

It seems to me that the person to ask this question is to Roger Shawyer: where is Shawyer getting the information that NASA measured a force towards the big base?  It may be simply an error on Shawyer's part.
« Last Edit: 07/29/2015 01:59 PM by Rodal »

Online Rodal

  • Senior Member
  • *****
  • Posts: 5834
  • USA
  • Liked: 5901
  • Likes Given: 5249
Thanks to Dr Tajmar for his paper and willingness to dip into a controversial area. I venture to say that those playing it safe, sitting back and not piecing something together should give him some props for outside the box thinking.

That being said:

Size matters - After reading the paper and about anything else I can find, his frustum design and launcher probably should have been more conventional (upsized) so we can compare relative apples to relative apples. While the miniaturized version is interesting, it appears we may need to work in a larger scale, at least at 2.45 GHz.

Oxidation - Yes, I can relate to this. Before I began thermal testing, I removed LOTS of black copper oxide which had been deposited at room temperature storage. Copper flashing on RF modules are quickly covered with silver or nickel, to prevent this. It will add weight and more importantly, degrade performance. I suggest all oxides be removed prior to any electrical testing.

Adhesives - Nope, not using any. Solder only with excess flux removed. Outgassing can happen with them.

Dissimilar metals - Normally do not use different metals for supression of intermodulation, but also for potential buildup of galvanic corrosion over time.

Balance beam - Respectfully disagree with this method being useful. Sticking with it for now.


The main issue with Tajmar's test was the ridiculously low Q (less than 50).  This is the most important thing he should address.  Possibly due to overcoupling.

Exciting the lowest mode (TE111) at 2.45 GHz instead of higher modes makes eminent sense, since lower modes should produce higher response.  To excite the lowest mode (TE111) at 2.45 GHz you need to make the cavity smaller.  Otherwise, at the same size you are using for NSF-1701, you need to excite around 1 GHz, because the natural frequency of TE111 for NSF-1701 size is around 1 GHz.

I question whether he would have been able to measure ANY force with a Q below 50 if he would have used higher modes like TE012 (used by Yang), TM113, (both of these previous ones possibly excited by Yang/Shell) TM114 or TM212  (NSF-1701 and NASA) that would take place in a bigger cavity.

I would actually predict that if you try NSF-1701 with a Q below 50 you will be hard pressed to measure a force.

Shawyer probably gave the go ahead to excite TE111 with a smaller cavity, but probably was not involved in the Q=50 overcoupling.  Shawyer is probably pleased to find out that even with a Q=50 (below) and if one can measure the tiny resultant force, the force still fits the semi-log linear with Q formula --that's what he probably finds very comforting about this experiment.  That's why he has now published the formula showing Q semi-log linearity.

Notice that Shawyer's graph is not a linear graph (as what his formula would require), but it is a semi-log graph.  He probably does this due to the huge range of Q's in the graph, which would be difficult to graph otherwise.

The formulas of Shawyer, McCulloch and Notsosureofit are linear with Q, which is not strictly linear in a semi-log scale.
« Last Edit: 07/29/2015 02:19 PM by Rodal »

Offline wallofwolfstreet

  • Full Member
  • *
  • Posts: 165
  • Liked: 169
  • Likes Given: 436
Why is shawyer's updated results saying that dresden measured 0.164mN of trust when the report said 0.020mN

Is specific Force / kW. So 164uN/kW.

The vacuum Force can be thrown, IMO, away as the cavity insides were oxidised and there were numerous issues with the vac test rig that need sorted.

Here are averaged the atmo Force measurements from 38 test runs.

But then:

Looking at the Up and Down Force curve chart I created from the Tajmar summary it suggests:

Peak powered Up force was 620uN
Peak powered Down force was -391uN.
From that Up buoyancy Force was 115uN.
Adjusted Up and Down peak powered Forces are then 505uN at 660W (VSWR 1.622:1) or 0.765mN/kW.

Further adjusting the specific Force for Q 48.8 to Q 50,000 yields 784mN/kW which brings the specific Force into the range I would expect.

So which one is it?  Is the specific force for the Tajmar emdrive 164 uN/kW or 765 uN/kW?  From my read of that paper, I'd go with the force measurement in a vacuum (since two experiments now have indicated force drops in vacuum, and ultimately vacuum is the only thing that matter for a propellant-less propulsion system).  So then it would be 20 uN for 700 W, or 28.6 uN/kW.  About 8.6 times better than a photon rocket.
« Last Edit: 07/29/2015 02:21 PM by wallofwolfstreet »

Offline WarpTech

  • Full Member
  • ****
  • Posts: 1223
  • Do it!
  • Vista, CA
  • Liked: 1290
  • Likes Given: 1740
...How do you reconcile this line of argument with the (way above) 6 orders of magnitude difference in time constants between decaying resonant EM energy (about 1s for high Q, probably less than 100ns at Q=50) and apparent lingering "thrust" decaying time >>1s ?...
Tajmar's Fig 5b which shows a summary of the small end Up, small end Down and small end Horizontal might be seen to be making an incorrect conclusion.

I took the Down curve and inverted it to show the negative Forces generated in the 2nd attachment. What we see is the lingering, after power off Force being generated in each direction. Buoyancy could not do this as it would only generate lift and not generate a lingering downward Force.

There does appear to be buoyant in effect as the Up force is greater than the Down Force by 229uNs or a bouyancy Force of 115uN applied to a +505uN Up Force and to a - 505uN Down Force.

Why both the Up and Down Forces lingered after power off is a question to be answered.
I question the elasticity of the scale as being responsible for not springing back.  We should not assume that the scale acts like a perfect elastic body.

To analyze why the scale is not acting as perfect elastic we would need to analyze the Sartorius AX224 scale.

Hold on, it's not just the scale. Tajmar says his scale and setup was capable of measuring forces < 1uN. This must require that the restoring-force of the scale that is coupled to his balance is << 1uN. We are used to seeing real-world forces, where scales "snap-back" to zero very quickly because the internal spring mechanism or whatever supplies the restoring force is strong. Here, the restoring force is necessary weaker than the EM drive thrust. Such a tiny restoring force "should" take a long time to restore the balance to equilibrium once the thrust is removed. If he had a setup where the balance quickly went back to zero, it would not be able to measure such small forces accurately.

The DIY's using balance beams should consider that if it's oscillating, it will have a very slow oscillation before it comes to a complete stop. How slow? Could it take minutes to settle? I'm sure it could if the restoring force is << 1uN!
Todd
« Last Edit: 07/29/2015 02:33 PM by WarpTech »

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
Looking at the Up and Down Force curve chart I created from the Tajmar summary it suggests:

Peak powered Up force was 620uN
Peak powered Down force was -391uN.
From that Up buoyancy Force was 115uN.
Adjusted Up and Down peak powered Forces are then 505uN at 660W (VSWR 1.622:1) or 0.765mN/kW.

Further adjusting the specific Force for Q 48.8 to Q 50,000 yields 784mN/kW which brings the specific Force into the range I would expect.

No, over your excitement you get it all wrong : both the up and down set ups do record a force up.
Peak powered Up force was +620uN
Peak powered Down force was +391uN.
With algebraic values positive upward.

Please check Tajmar paper, only in the case of the latest experiments horizontal pendulum with no magnetic damping there is inversion of thrust following geometrical 180 turn of test article :
Quote from: Tajmal et al. page 8
The negative thrust orientation went indeed negative down to -27 μN. This was the first time that we have actually seen a real thrust reversal.

Bold added for emphasis. Notice this is also the only force indicated as negative, and all other "real" thrusts are obtained by subtracting. In air on vertical scale this is not ((+620)+-(-391))/2 as you think, it is (+620)-(+391)=229N of difference, that would amount to 229/2 = 114N above and below an hypothetical symmetrical spurious orientation independent rising force (such as buoyancy). Albeit in such interpretation the horizontal "null" should record a plot between the up and down (making possible an average). So this really makes no sense at all, but there clearly isn't much of an ambiguity that your interpretation is wrong.


Online Rodal

  • Senior Member
  • *****
  • Posts: 5834
  • USA
  • Liked: 5901
  • Likes Given: 5249
...Hold on, it's not just the scale. Tajmar says his scale and setup was capable of measuring forces < 1uN. This must require that the restoring-force of the scale that is coupled to his balance is << 1uN. We are used to seeing real-world forces, where scales "snap-back" to zero very quickly because the internal spring mechanism or whatever supplies the restoring force is strong. Here, the restoring force is necessary weaker than the EM drive thrust. Such a tiny restoring force "should" take a long time to restore the balance to equilibrium once the thrust is removed. If he had a setup where the balance quickly went back to zero, it would not be able to measure such small forces accurately.

The DIY's using balance beams should consider that if it's oscillating, it will have a very slow oscillation before it comes to a complete stop. How slow? Could it take minutes to settle? I'm sure it could if the restoring force is << 1uN!
Todd

That's correct.  It is not just the scale itself but the beam balance mechanics that are very much at play here.
« Last Edit: 07/29/2015 02:47 PM by Rodal »

Offline Chrochne

  • Full Member
  • *
  • Posts: 182
  • Liked: 104
  • Likes Given: 247
New comment by Martin Tajmar
« Reply #5619 on: 07/29/2015 02:57 PM »
I just come across an article that was posted 60 minutes ago. IBT talked to Prof. Martin Tajmar and here are his comments. It does not sound encouraging for the enthusiast side of the spectrum  :( . I guess critics might celebrate their victory this or next year. I just hope they will at least be more polite than Mr. Sean Caroll.

Here is the extract and the link

http://www.ibtimes.co.uk/emdrive-dr-martin-tajmar-generates-thrust-test-controversial-space-propulsion-technology-1513151

"Next steps include better magnetic shielding, further vacuum tests and improved EmDrive models with higher Q factors and electronics that allow tuning for optimal operation. As a worst case we may find how to effectively shield thrust balances from magnetic fields."

Tajmar told IBTimes UK that he feels his EmDrive experiments are just a "work in progress" at the moment. "I believe there is no real news here yet. I specifically wrote in the abstract and conclusion of the paper that our measurements can not confirm or refute anything here regarding the EmDrive."

"After building our own setup we did indeed measure effects similar to what you would expect from an EmDrive - but also in directions where you would expect zero thrust. Our setup therefore produced a null effect within our measurement resolution which is on the order of the claimed thrust we did identify magnetic forces from the power cables that may still lead to a significant influence which must be assessed in future work."

Tags: