Author Topic: EM Drive Developments Thread 1  (Read 764004 times)

Offline IslandPlaya

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Re: EM Drive Developments
« Reply #400 on: 09/08/2014 08:45 AM »
Great post!
Welcome to the forum.

Offline Star One

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Re: EM Drive Developments
« Reply #401 on: 09/08/2014 03:42 PM »

Great post!
Welcome to the forum.

Be interesting to hear about the response as I imagine that is just one amongst many, many pieces of correspondence that have no doubt been fired in his direction since the announcement.

Offline aceshigh

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Re: EM Drive Developments
« Reply #402 on: 09/08/2014 05:59 PM »
insteresting...

considering NSF user Stardrive (Paul March) works with Dr. Sonny White at Eagleworks Lab, specifically at the Q-Thrusters experiments (though if I am not mistaken he attributes the effects to Woodward Effect), I wonder if there would be any chance of him answering that.
« Last Edit: 09/08/2014 06:53 PM by aceshigh »

Offline sghill

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Re: EM Drive Developments
« Reply #403 on: 09/08/2014 11:39 PM »
insteresting...

considering NSF user Stardrive (Paul March) works with Dr. Sonny White at Eagleworks Lab, specifically at the Q-Thrusters experiments (though if I am not mistaken he attributes the effects to Woodward Effect), I wonder if there would be any chance of him answering that.

Well, I think Dr. Jose was mixing up EMDRIVE with Qthruster, but otherwise, let's hope for a response.
Bring the thunder Elon!

Offline Rodal

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Re: EM Drive Developments
« Reply #404 on: 09/09/2014 12:12 AM »
The authors (Brady, White, et.al.) of the paper ("Anomalous Thrust..."July 28-30, 2014, Cleveland, OH; AIAA/ASME/SAE/ASEE Joint Propulsion Conference) referred to ALL the tested thrusters, in general as  "potentially interacting with the quantum vacuum" in their abstract:

<<Test campaign results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma>> (Abstract)

or "potentially a Q-thruster":

<<... the RF launcher tube assembly with dielectric cylinder common to both the [Cannae] slotted and smooth test articles is potentially a Q-thruster where the pillbox is simply a matching network>> (p.10)

<<Tapered Cavity RF Evaluation, General Findings and Lessons Learned...We discovered early in the COMSOLŪ analysis process that just because you can achieve a great RF solution does not mean that it will be an ideal Q-thruster implementation.>> (p.18)

<<The near term objective is to complete a Q-thruster breadboard test article that is capable of being shipped to other locations which possess the ability to measure low thrust for independent verification and validation (IV&V) of the technology>> (p.21)

<<D. A. Brady... thanks Kent Joosten for his substantial contribution to Q-thruster mission analysis>> (p.21)

So, I intentionally adopted the author's general description of "Q-thruster" for all the devices tested by the authors  in their paper, because the different explanation I offer above (transient thermal unsymmetric expansion) for their experimental measurements applies equally well to all the different types of devices (both the Cannae-type and the Tapered Cavity ) tested by the authors.
« Last Edit: 09/09/2014 01:12 AM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #405 on: 09/09/2014 12:52 AM »
Furthermore, Dr. White himself has repeatedly used the general word "Q-thruster" in the past to refer to ALL of the electromagnetic devices he has tested (including the EM Drive).   

For example see slide 40 of his presentation "WARP FIELD PHYSICS" (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140000851.pdf ) where he shows photographs for six different test campaigns for different devices (including the Boeing, Lockheed-Martin, EM Drive, Cannae, and two others) ALL under the same title of "Q-thruster Physics Data"
« Last Edit: 09/09/2014 12:58 AM by Rodal »

Offline Slyver

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Re: EM Drive Developments
« Reply #406 on: 09/09/2014 09:28 AM »
@Rodal

Can you provide the calculations you used for your analysis?

I attempted to do a quick model of the system with your ideas.  Using a few assumptions:

-- 25mm diameter x 5mm height cylindrical dielectric
-- 150mm length cavity
-- 5 degrees increase in temperature
-- Thermal expansion of the dielectric peaked instantly

I got a tangential torque of -5.6 x 10^-7 NM.  This is in the opposite direction, and two orders of magnitude less than the net force on the system.

The dielectric, assuming it was fastened to the top of the cavity (i.e. the face in the direction of the thrust) expands in the opposite direction (outward from the face) and thus changes the center of gravity of the system in the same direction as the expansion (and opposite of the measured thrust).

I did not run an analysis of the rate of thermal expansion of the dielectric, but you seem to have its net thermal expansion at the measured thrust (i.e. after 1s) ~ the same as its steady state expansion at the increased temp, and yet you state in your email only how long it takes to reach steady state.  The measurements in the data show both a very sharp increase in thrust (~1s from 0 to peak) and peak equal to initial thrust, suggesting by your model that there is no increase in thermal expansion between 1s and steady state (minutes).

I am only asking for detailed explanations (in both math and words preferably), not saying you are incorrect.  It is entirely possible I made mistakes in both my assumptions and my quick math.

Offline aceshigh

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Re: EM Drive Developments
« Reply #407 on: 09/09/2014 02:38 PM »
Rodal, I posted your question at Talk Polywell Forum, where Paul March (who works at Eagleworks Lab with Dr Sonny White, at the Q-Thrusters, and I guess also took part in the investigation of the EMDrive) sometimes reads stuff.


Here is his answer:

Quote
AcesHigh:

You can inform Dr. Rodal that most of the observed forces in the Eagleworks Lab frustum devices were prompt with the same rise and fall times as our electrostatically derived calibration forces and therefore are not thermal in origins. That's not to say we didn't see thermal effects, especially with input RF power levels greater than ~35W, but the thermal effects with these large copper plus dielectric test articles, (2.5 to 5.0kg), always take tens of seconds to develop and are easily distinguished from the prompt E&M or more interesting force inputs since they always exhibit exponential rise and fall times.

BTW, the copper frustum's temperature never rose more than 1.0 degree F. when using the above average power levels and test articles.

Best,
Paul March


« Last Edit: 09/09/2014 03:05 PM by aceshigh »

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #408 on: 09/09/2014 02:46 PM »
I have concluded that thermal transient effects are a likely explanation for the measured deflections and forces in NASA's torsion pendulum experiments of the Q drives.  Explicitly, that they are the result of a shift in material location of the center of mass due to differential thermal expansion resulting from heating of the dielectric resonator which is positioned unsymmetrically. ...

I hope that these considerations, convince you ... that thermal transient effects are important and therefore that it merits strong consideration that the measured deflections and forces in your torsion pendulum experiments of the Q drives are the result of a shift in material location of the center of mass due to differential thermal expansion resulting from heating of the dielectric resonator which is positioned unsymmetrically, as explained above.

Thank you very much for the quite readable analysis.

1.  Could you provide your calculations, following the order of your correspondence, perhaps tagging the calcs to the paragraphs?

2. It seems clear that vacuum testing of the device would be necessary.  Could you describe or sketch a possible experimental mechanism which would more closely simulate an unrestrained body?

3. Is the torsion pendulum the only way to test a device of this sort on Earth?

4.  How crucial is the dimension of the Teflon resonator to your argument?
« Last Edit: 09/09/2014 02:48 PM by JohnFornaro »
Sometimes I just flat out don't get it.

Offline aceshigh

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Re: EM Drive Developments
« Reply #409 on: 09/09/2014 03:05 PM »
@John Fornaro: I just posted an answer by Paul March, who works with Dr Sonny White, regarding Radal's questions.


--------------------------------

kinda off-topic, but is Dr Rodal's first name (José) of portuguese or spanish origin? It changes the way the J is pronounced (if portuguese, itīs similar to english J in Joseph, not the SAME sound, but closer to it than to Spanish J)
« Last Edit: 09/09/2014 03:31 PM by aceshigh »

Offline sghill

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Re: EM Drive Developments
« Reply #410 on: 09/09/2014 03:19 PM »
@John Fornaro: I just posted an answer by Paul March, who works with Dr Sonny White, regarding Radal's questions.

Irrespective of the science, what an awesome use of this forum- and thread!  Thanks to Aces, and John, and Dr. Jose, and Paul for all your contributions!!

How exciting. :)
Bring the thunder Elon!

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #411 on: 09/09/2014 04:13 PM »
Quote from: rodal
However, I have wondered how air convection could be responsible for the reproducible and fairly consistent levels of measured force pulse, as well as the fact that the experimental pulses are so well defined (and that it took practically no time to achieve the measured forces and to go back to zero upon ending the microwave pulse), and that turning the Q-drive around by 180 degrees resulted in practically the same force in the opposite direction.

Quote from: March
You can inform Dr. Rodal that most of the observed forces in the Eagleworks Lab frustum devices were prompt with the same rise and fall times as our electrostatically derived calibration forces and therefore are not thermal in origins.

Rodal has noticed the "prompt" and "well defined" rise and fall times of the measured forces; that part at least, has not been overlooked, nor answered.  Rodal goes on to discuss the rather long times for the Teflon to achieve a thermal steady state, but what Rodal doesn't do is offer his suggestion as to the speed and dimension of the "reaction force" caused by the dielectric resonator, and how it relates to the prompt and well defined rise and fall times of the measured forces.

That's why I asked about the dimensions of the Teflon. 

In order for the device to operate for several days (as if it were flying to the Moon) it would have to be operated rather continuously, and there would be some kind of steady state operation that would have to be engineered.  But that would be a future game.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #412 on: 09/09/2014 05:06 PM »
I'm glad that I posted in this forum, great, quality feedback :D  Thanks to everyone for your comments.

I'll try to answer this evening when I have time available.


____________

@aceshigh, thank you for your initiative to pursue this with Paul March. Please thank him for his answer, which is much appreciated.  It would be great if you could pursue further answers to the following questions:

1) What was the length (between upper support and lower fixture point) of the pendulum ?

2) What was the total weight suspended on the pendulum ?

3) What were the different shapes (cylindrical, disc, etc. ?) and the dimensions of the Teflon dielectric resonators that were used in the experiments?

4) What were (all) the surface Boundary Conditions of the Teflon dielectric resonators ? how were the dielectric resonators put in position?

___________
@aceshigh: answering your off topic question, my first name is a geographic accident of being born in a country where (at that time) there was a law that everyone born there had to be given names chosen from a Government-provided list.  .  The "J" is pronounced as an "H":D
« Last Edit: 09/09/2014 07:49 PM by Rodal »

Offline aceshigh

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Re: EM Drive Developments
« Reply #413 on: 09/09/2014 05:33 PM »
@aceshigh: answering your off topic question, my first name is a geographic accident of being born in a country where (at that time) there was a law that everyone born there had to be given names chosen from a Government-provided list.  .  The "J" is pronounced as an "H":D

if itīs pronounced as an english H, then I guess itīs of spanish origin. I asked because I am brazilian, and as a portuguese speaker, I have the tendency to read José with the portuguese J.

(google translate pronounciation button is very good for these matters, if you are curious)

I will forward your questions to Paul March. I am not sure he can answer all of them. I remember reading a couple of years ago that he had signed a non-disclosure contract with NASA or maybe with Dr White, which was when he stopped being active both here at Nasa Spaceflight Forum and TalkPolywell forum... he used to post LOTS of info about his workings with Dr James Woodward at Mach Effect and such.

Offline Rodal

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Re: EM Drive Developments
« Reply #414 on: 09/09/2014 07:38 PM »
My understanding is that White et.al. used an inverted torsion pendulum for their experiments.  If there are Non Disclosure Agreements, they must deal with the inner workings of proprietary drives that were tested, but I imagine that the inverted torsion pendulum should NOT be part of these NDA's.  Since White et.al. published their experimental results performed at NASA, I would imagine that a description of the experimental procedure, most importantly the pendulum geometry, should be part of their description for the scientific/engineering community to review, and this would not be covered by NDA's.

My pendulum geometry questions are then more properly framed as follows:

1) What is the length of the inverted torsion pendulum between the lower torsional support and the upper centering bearing ?

2) What is the total weight of the upper portion: the tested object, its support table,  and any other fixtures and equipment on the table?

3) What is the maximum off-center motion allowed by the centering bearing ?

4) What is the spring constant (about a rotating axis normal to the vertical arm of the pendulum) of the bottom joint that tries to keep the inverted pendulum upright in a vertical position?

Offline aceshigh

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Re: EM Drive Developments
« Reply #415 on: 09/09/2014 08:01 PM »
itīs possible Rodal. I already forwarded your previous questions to the Talk Polywell forums, but I also asked Dr Paul March if he could answer your questions directly here, so I can stop playing messenger boy haha ;)

Offline aceshigh

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Re: EM Drive Developments
« Reply #416 on: 09/09/2014 08:06 PM »
Mr Chang from NextBigFuture already caught on to the interesting discussion going on between Dr Rodal and Dr March and posted an update at his site:
http://nextbigfuture.com/2014/09/nasa-cannae-drive-and-emdrive.html

Offline Rodal

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Re: EM Drive Developments
« Reply #417 on: 09/10/2014 12:43 AM »
I attempted to do a quick model of the system with your ideas.  Using a few assumptions:.....
I got a tangential torque ... in the opposite direction, and two orders of magnitude less than the net force on the system.
@Slyver

First of all thank you for taking the time and initiative to do your own independent modeling.  We face at least three problems in modeling this experiment: 1) the NASA paper does not describe the experiment with enough detail that we can model it without making a number of assumptions (hopefully we will get some more details in the future), 2) the experimental set-up is not trivial (for example: the inverted pendulum) and 3) the measured force is extremely small so a number of normally negligible effects can be responsible.   By working independently yet asking questions about our models perhaps we can eliminate some possibilities, correct our models and narrow down the possible explanations.

So let me start with the force that I did not explicitly mention in my write-up nor it appears in yours: gravity.  Did you model the inverted torsion pendulum?

- I am multi-tasking  - running some programs while I'm writing this, so I will do this in short segments.  The next one to follow discussing my inverted pendulum  modeling


Offline Rodal

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Re: EM Drive Developments
« Reply #418 on: 09/10/2014 12:56 AM »
@Slyver  (CONTINUED)

The motion of the inverted torsional pendulum is, in general. the combination of 3 types of oscillation: 1) Torsional,
2) Swinging and 3) Bouncing.  I neglected the (vertical) bouncing oscillation under the assumption that the pendulum's vertical arm (some people call it "leg") is stiff enough (in relation to the supported mass) so that the longitudinal "bouncing" vibration displacements are negligible (of course, we would need to double check this assumption once we know the supported mass and the arm's dimensions and material construction).

Offline Rodal

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Re: EM Drive Developments
« Reply #419 on: 09/10/2014 01:10 AM »
@Slyver  (CONTINUED)

I modeled the swinging oscillation of the inverted pendulum with a natural (angular) frequency

omega= Sqrt[(k/M)-(g/l)]

where:

k= spring constant (about a rotating axis normal to the vertical arm of the pendulum) of the bottom joint that tries to keep the inverted pendulum upright in a vertical position

M=total supported mass ( total weight of the upper portion: the tested object, its support table,  and any other fixtures and equipment on the table)

g=acceleration of gravity

l=length of inverted pendulum's arm between the lower torsional support and the supported mass


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