Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1878521 times)

Offline SeeShells

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

  It seems that they no longer use the magnetic suspension as in their first test.
  That's good since the magnetic field could have coupled with the rest of the assembly and transmit momentum to it.

  Did they explain their reasons for abandoning the magnetic suspension ? I can't find anything on their web site.
This maybe of use as to why they might be seeing oscillations on the pendulum. Living in California we had suspended a string with a weight on it about 4 foot long. It would start to move and oscillate on its own. The reason was minor tremors and earthquakes would cause the pendulum to move (P and S waves) as the waves from the quakes would travel under it. The rest of the earth would move but the end with the weight would not until it recentered itself to earth's gravity.   I was surprised at the number of minor quakes.

Offline Prunesquallor

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.
« Last Edit: 06/14/2015 05:01 PM by Prunesquallor »
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Offline Rodal

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

Thank you for taking the time to do that.

What information do you gather from this exercise?  Do you get information here pointing towards the EM Drive displaying what has been claimed as thrust by other researchers ?

To me it seems like a null test, with a lot of noise and no thrust signal.

Offline zen-in

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Second test of the baby EM drive and problems with oscillation. I think they are looking for suggestions to resolve this?

https://www.youtube.com/watch?v=Y8uyIgzdzS4&feature=youtu.be

More info.

https://hackaday.io/project/5596-em-drive/log/19417-torsion-test-no-data-due-to-oscillations

My guess is the pendulum is being excited by vibrations.   Even the smallest vibration or movement of the whole apparatus will make the pendulum swing back and forth at its natural frequency.   This effect is much more noticeable than any possible thrust from the RF.   A method used by holography experimenters is to use a container filled with sand as the base, and have that container situated on a concrete floor.  The apparatus has legs that are sunk into the sand.   Any table or floor of a wood frame house will be swaying from vibrations, wind outside, etc.   This movement is coupled to the whole apparatus, making the pendulum swing.  But the effect of seismic activity, waves crashing on a distant shoreline, heavy trucks passing, construction activity, etc, etc, will still affect the measurement.   Any thrust from the RF will always be too far below the noise level to even be measured, no matter what methods are used to analyze the "data".
« Last Edit: 06/14/2015 05:19 PM by zen-in »

Offline Prunesquallor

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

Thank you for taking the time to do that.

What information do you gather from this exercise?  Do you get information here pointing towards the EM Drive displaying what has been claimed as thrust by other researchers ?

To me it seems like a null test, with a lot of noise and no thrust signal.

It's pretty noisy.  I might believe that I see depression of the mean during the first long thruster on-time.  But I would have to want to believe.

If anyone knows of a better technique of extracting S/N that Excel could handle, I'd be will to try.
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Offline SeeShells

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

Thank you for taking the time to do that.

What information do you gather from this exercise?  Do you get information here pointing towards the EM Drive displaying what has been claimed as thrust by other researchers ?

To me it seems like a null test, with a lot of noise and no thrust signal.

It's pretty noisy.  I might believe that I see depression of the mean during the first long thruster on-time.  But I would have to want to believe.

If anyone knows of a better technique of extracting S/N that Excel could handle, I'd be will to try.
this help any?
http://www.bostonaudiosociety.org/articles/extracting_data_from_excel.htm

Offline Rodal

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

Thank you for taking the time to do that.

What information do you gather from this exercise?  Do you get information here pointing towards the EM Drive displaying what has been claimed as thrust by other researchers ?

To me it seems like a null test, with a lot of noise and no thrust signal.

It's pretty noisy.  I might believe that I see depression of the mean during the first long thruster on-time.  But I would have to want to believe.

If anyone knows of a better technique of extracting S/N that Excel could handle, I'd be will to try.

I have dozens of tools that I use  for processes governed by non-stationary randomness, from simple Autocorrelation, and Power Spectral Density computations, to non-parametric statistical methods and more complicated stuff, but what I see in this output is that there is no useful recoverable signal here.   Even in the stock market one sees "signals" that are not really there (they are constructs of the mind).  This output is even worse.

The human mind is built by Nature to see patterns.  Often, humans see patterns where there is just noise (the face on Mars, the face on the Moon, trees on Mars, canals on Mars, artificial patterns in the stock market, etc. etc.)

Here, even the human mind cannot even see a pattern, and much less a trend.  And the amount of data is really not massive enough to do much statistical analysis either.

I don't understand why they are using water instead of oil to dampen the oscillations.
« Last Edit: 06/14/2015 07:05 PM by Rodal »

Offline Prunesquallor

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

Thank you for taking the time to do that.

What information do you gather from this exercise?  Do you get information here pointing towards the EM Drive displaying what has been claimed as thrust by other researchers ?

To me it seems like a null test, with a lot of noise and no thrust signal.

It's pretty noisy.  I might believe that I see depression of the mean during the first long thruster on-time.  But I would have to want to believe.

If anyone knows of a better technique of extracting S/N that Excel could handle, I'd be will to try.
this help any?
http://www.bostonaudiosociety.org/articles/extracting_data_from_excel.htm

Yeah,I was thinking about trend lines, but didn't know what they would mean with (potential) step functions in the input.  Maybe just an average value of the data during each of the thruster on/off periods.

Will have to come later - being take to "Jurassic World" for Father's Day.  Dinosaurs for Father's Day!  How cool is that?
« Last Edit: 06/14/2015 05:24 PM by Prunesquallor »
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Offline SeeShells

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And a Happy Fathers Day to all the Fathers!

Offline RotoSequence

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Isn't Father's Day on the 21st?  ???

That second set of Baby-EM drive data doesn't look like much more than noise, to me.  :-\

Offline deltaMass

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

Thank you for taking the time to do that.

What information do you gather from this exercise?  Do you get information here pointing towards the EM Drive displaying what has been claimed as thrust by other researchers ?

To me it seems like a null test, with a lot of noise and no thrust signal.
Concur.

I see pretty much zero correlation between drive on/off and the data itself.
Said otherwise, a high confidence level in the null hypothesis.
Said otherwise, there is no "there" there in this test.

Test #1 is a lot more convincing.

Offline Star One

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And a Happy Fathers Day to all the Fathers!

Father's day is Sunday, June 21 in the USA  ;)

(I just asked my children  ;) )

And the UK.

Offline SeeShells

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And a Happy Fathers Day to all the Fathers!

Father's day is Sunday, June 21 in the USA  ;)

(I just asked my children  ;) )
Wanted to be the first?
I'm off to a 50th birthday and Fathers Day cookout. So poo I'm confused. ;)

Offline deuteragenie

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Data from second Baby EmDrive test

https://hackaday.io/project/5596-em-drive/log/19468-torsion-test-2-data

Using their data, I plotted maxima and minima, then averaged: ave(t) = [min(t)+max(t-1)]/2.  Thruster on/off times were interpreted from hackaday plot.

As others have said you would need to perform proper signal / time series analysis on this to be sure.
Maybe something that could be useful for a start is if to compute the average the Ys for the periods where the drive is "off" and then for the period where the drive is "on".  Is there any noticeable pattern ?
 

Offline rfmwguy

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Any signal that cannot escape noise is likely zero. Null test is my vote for our Aachen friends.

Offline deltaMass

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My advice is "give it up" for this test #2. The "signal" is so small and the amount of data taken so small that "it doesn't work in this configuration" pretty much covers it.

What's needed now is a repeat of Test #1 in vacuum.

Offline snoozdoc

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 ... Imagine the space shuttle in orbit. The cargo bay doors are open. An astronaut equipped with an MMU fires his gas jets, accelerates from space outside the shuttle, and smacks into the back wall of the cargo bay. The astronaut transfers his momentum to the shuttle, and recieves a concussion for his trouble.

The momentum flow is Gas from the Jets go left, shuttle goes right. CoM is satisfied.

Two asprin later the astronaut+mmu is in the cargo bay with the bay doors closed and sealed. The bay is a hard vacuum. The astronaut reluctantly fires the MMU jets and smacks into the back wall again. A small amount of momentum is transferred to the shuttle, and the astronaut rethinks his "glamorous" career with Nasa.

For conservation of momentum to be satisfied the force of the gas striking the inside of the cargo bay must exactly balance the force of the shuttle to the right for there to be no net momentum change. This exact balance of gas pressure does not match my understanding of gas behavior at all. I expect instead to see the all kinds of non-Newtonian action in the gas as it expands randomly into the bay in all directions. Turbulence and brownian motion will rob energy out of the gas literally left and right.

I also don't see what would prevent the astronaut from pulling out a vacuum pump and compressing it back into the MMU's cylinders for another shot.
...


When we were taught CoM at school, our physics teacher encouraged us to think of the centre of mass of our systems.  The trick he was trying to get us to understand was what exactly comprises “the system”.

He suggested we think about rockets (the Gemini test flights had just ended as I recall).  He explained that even with rockets, the centre of mass also remains either stationary or in it’s original path (before its engine is lit) when you consider the  entire system.  Thus when a rocket fires its engine, the rocket moves in one direction and gains a lot of momentum.  But when you consider all the exhaust it throws out of the back, the centre of mass of all that exhaust and the rocket combined remains either stationary or continues in its original path.  (At that age we hadn’t yet discussed reference frames). 

At first this might not seem true because the rockets mass is (generally) much larger than the exhaust and of course it moves.  But the exhaust travels at a much higher velocity and thus in a given time has moves a lot further than the rocket, so the centre of mass remains un-accelerated, continuing in whatever path it originally was in.  The only thing that has changed is the geometry that encloses the system ... it takes up a lot more space!

When one of us asked in class if that was the case when the rocket was launched from earth, I remember our teacher fascinating us by explaining that when you consider all the rockets that had ever been launched from earth, including those that had headed to the moon, mars and those that had missed the moon and got lost in space etc, then the centre of mass of all the atoms in the system which included earth, the rockets and their exhaust material, the moon and mars etc was still continuing in its exact same path it always had.  Its just that the geometry of the system had changed.

That was a pretty powerful notion we had of CoM at age 15 … but a useful one.

When thinking of the astronaut in the cargo bay of the shuttle with his/her gas powered MMU the same thought about what happens to the centre of mass of the system including the exhaust atoms of the MMU should help keep the picture straight.  The geometry of the mass changes but the centre of mass will continue in the same path it always was.  Even with the astronaut bouncing back and fort inside the cargo bay the center of mass will remain in its original path.

The gut feeling I still have is that this is true even with the EM drive and that the thrust that has been measured in these EM drive experiments is either accumulation of measurement errors caused by inadequate understanding of noise sources in the experimental set-up or … and much more interestingly (if extremely unlikely) ... we haven’t yet figured out what the entire system consists of.  This would mean extending the system into fringe physics such as quantum vacuums and the like.  The engineer and space enthusiast in me would love to believe the latter which is why I too am trying to cobble together an experiment.  The gambler in me however is giving astronomical (pun intended) odds against it. 

But if nothing else it is a great learning opportunity for many of us to brush up on our math and physics. 8)

« Last Edit: 06/14/2015 07:48 PM by snoozdoc »

Offline TheTraveller

I added the TE012 NASA test without dielectric insert that registered no thrust force to the EM Drive Experimental Results wiki:

http://emdrive.wiki/Experimental_Results

including a note reading: "@TheTraveller made an argument that the test may have been conducted at the wrong (too low) frequency for resonance"

QUESTION: does anybody have a link to TheTraveller's message where he points out that the test may have been conducted at the wrong frequency, so that the note can link to the message?   Thanks

My spreadsheet can now quickly test 40 x TEm,n,p and 40 x TMm,n,p combos at a set input frequency and find the closest match in terms of physical to theoretical end plate spacing.

Once the best mode is found, Excel Goal Fit can then find the exact frequency to match the physical end plate spacing.

With the EW test of their frustum without a dielectric, my evaluation is showing the excitation at 2.168GHz operates the frustum below cutoff for most common modes.

Will shortly post the results.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline flux_capacitor

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QUESTION: does anybody have a link to TheTraveller's message where he points out that the test may have been conducted at the wrong frequency, so that the note can link to the message?   Thanks

In this post and the following:
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1382477#msg1382477

Offline Rodal

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QUESTION: does anybody have a link to TheTraveller's message where he points out that the test may have been conducted at the wrong frequency, so that the note can link to the message?   Thanks

In this post and the following:
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1382477#msg1382477

Thank you !!!!

Much appreciated.  :)

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