Author Topic: EM Drive Developments Thread 1  (Read 797126 times)

Offline Rodal

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Re: EM Drive Developments
« Reply #2740 on: 10/28/2014 02:50 PM »
...
I'm assuming this was tested with internal vacuum. Or was it just frozen air that was vaporized by RF energy?

Quote
the POC cavity and attached vacuum tubing are only supported by the central vacuum pipe depicted in Figure 4. The central vacuum pipe is attached to a support arm depicted in Figure 4. During experimental runs, the cavity and attached vacuum tubes are supported by two Cooper Instruments LFS 210 load cells.
....
the helium dewar depicted in Figure 4 is vacuum sealed.  Pressure over the liquid helium is reduced to 50 Torre reducing its temperature to 2.3 K. Prior to experimental runs, the vacuum seal on the helium vessel is broken, bringing pressure above the liquid helium to atmospheric pressure. Tests on the cavity were then run while the liquid helium bath was below its atmospheric boiling temperature. The helium pump-down procedure eliminated boiling helium buoyancy beneath the cavity as a potential cause of false-positive experimental results.

Frobnicat: your comments would be appreciated whether the heated air artifact would be nullified by this test

« Last Edit: 10/28/2014 03:08 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #2741 on: 10/28/2014 02:51 PM »
I am starting to wonder if the info needed the most (predictive equations, measurements, frequencies) isn't hidden away by Non Disclosure Agreements.  Might account for the lack of later papers (after 2007) by Doctor White, and why getting other info is like pulling teeth.

There just doesn't seem to be all that much to most of these devices.  A competent machinist could probably build one in a weekend from scratch for not much more than beer money.  Oddly shaped and constructed microwave ovens basically.

Sonny told Pop Sci when they came for a visit that he was restrained by NDA, but there are long odds on that.  Who would have asked him to sign it?  (Apart from the outside work they did for Boeing, wich makes perfect sense.)  Rather he has likely asked others to so sign.  The real issue here is that Sonny can't patent anything since he didn't invent the stuff.  Best he can do is operate under trade secret status so you should not expect ever to get much detail about his setup.

BTW as we mentioned before, this cannot be done with a microwave oven magnetron.  It needs a continuous wave magnetron.  They're much more expensive, most often water cooled and not the kind of thing you can pick up on EBay for $25.  They draw several kW of power and if you mess up with one, they're fry the inside of your eyeballs in 3 seconds.  So this is  not as simple as it seems.

Nope, POPSCI got it wrong:

"Did Harold White sign NDAs as an individual or as a NASA civil servant? Who did he sign these NDAs with?

White has not signed any NDAs. The article has it backwards. In order for the Popular Science author to get briefed on the referenced technology, he would need to sign an NDA with the government as the noted technology has an invention disclosure. An NDA is the mechanism to protect the IP content, but still allow access to interested parties for consideration."

http://spaceref.com/nasa-hack-space/propulsion/clarifying-nasas-warp-drive-program.html

Challenge your preconceptions, or they will challenge you. - Velik

Offline Mulletron

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« Last Edit: 10/28/2014 03:03 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Rodal

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Re: EM Drive Developments
« Reply #2743 on: 10/28/2014 03:03 PM »
@Rodal

Is what you're looking for from Dr. White on page 5?

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023492.pdf

Thanks for taking the time to look for this, but no, this report by Dr. White does not contain any explicit equation with which one can calculate a thrust force.

Offline Mulletron

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Re: EM Drive Developments
« Reply #2744 on: 10/28/2014 03:24 PM »
http://www.nasa.gov/pdf/501329main_TA02-InSpaceProp-DRAFT-Nov2010-A.pdf

Here's some feel goods, for the dreamers out there.
Challenge your preconceptions, or they will challenge you. - Velik

Offline Mulletron

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Re: EM Drive Developments
« Reply #2745 on: 10/28/2014 03:33 PM »
@Rodal

Is what you're looking for from Dr. White on page 5?

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023492.pdf

Thanks for taking the time to look for this, but no, this report by Dr. White does not contain any explicit equation with which one can calculate a thrust force.

That's the most math I've seen come out of Dr. White's public releases on his QVT. That lack of usable material and transparancy is what drove me looking for the kind of answers linked to below.

I always suspected that White was just taking what he was researching about dielectric thrust and applying that to already known methodology used in ion thrusters or MHD drives, and getting his thrust calcs that way. I wasn't satisfied with that so I went looking for more.

http://forum.nasaspaceflight.com/index.php?topic=29276.msg1269074#msg1269074

« Last Edit: 10/28/2014 03:36 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Rodal

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Re: EM Drive Developments
« Reply #2746 on: 10/28/2014 04:01 PM »
The amplitude vs. frequency response is very nonlinear, and  the researchers don't quite know at what precise frequency the maximum amplitude takes place and they lack the precise equipment to keep the frequency steady at the peak amplitude.

Question: what's the speed of light

Wrong answer: an unqualified 299 792 458 meters/second

Correct answer: it depends on the medium


Add up to the fact that the experimenters don't precisely know the frequencies at which peak amplitude (and thus peak Q) resonance occurs, and they cannot keep the frequency within the very narrow bandwidth for high Q the fact that the speed of light depends on the medium, and the nonlinearities associated with dielectrics and what one has is a lot of confusion talk and confusion writing from the experimenters when dealing with dielectrics.  When dealing with dielectrics to me they are more like people feeling their way around a dark room, very empirically.  I write that, because none of the labs to my knowledge, including Eagleworks, has dielectrometry, DSC, TGA, TMA, DTMA, FTIR, MTS, and other means to properly assess the material properties of the polymer dielectric materials involved.

They put a dielectric in, the amplitude vs. frequency response changes, they feel their way around, sometimes they may end up with a higher amplitude.  It depends on their frequency sweep precision, tuning, staying within bandwith, etc.
« Last Edit: 10/28/2014 05:10 PM by Rodal »

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2747 on: 10/28/2014 04:15 PM »
It looks that you are assuming that one half is a male and the other half is a female and they mate with each other...

Nahh...   You really think I'm gonna fall for that one?

Not sure how they made the thing, but I was figuring the 1cm depth, plus a 0.5cm "lip", visible in the section and the detail.  You make two of the round things things, and join 'em lip to lip.  (don't start with a mating call, pardner)  Either you weld them together, or you mechanically fasten them with a 1cm (-) band.

Perhaps thru a lost wax process, you could make the hollow round thing, but I'm guessing not.  Note that their cut-away view kinda sorta implies that the fictional dewar was monolithically cast.

Count with me to six, now, willya?

Seriously, you say, "...to me they are more like blind people feeling their way around very empirically."  What is driving you to such exhaustive consideration of these various reports?
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #2748 on: 10/28/2014 04:20 PM »
There is no explicit mating shown in the referenced picture (reproduced below), and again you are considering the lip from only  one side.  There is also a contacting lip on the other side that I took into account as well as the curved recess from the other side.  There is no penetration shown in this picture so you have 1 cm + 0.4 cm lip + 0.6 lip + 1cm = 3 cm depth of cavity (measured in vertical direction)

« Last Edit: 10/28/2014 04:28 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #2749 on: 10/28/2014 06:02 PM »
...
Sorry, I re-checked the code because that statement about the 7 sec didn't make sense to me and I found an error on my definition of the exponential function (I had the variable "time" instead of "t" which mean different things in my code.  I'll be back with the correct result

Yes, any tau>0.2 sec is clearly discernable.

For tau ~ 1 sec the difference is unacceptable

I'll post some pictures tomorrow after I double check everything.   I need to do some work for which I get real $$$ first  :)

All right. I'm a bit surprised then. Maybe not 7s but 2s seemed like possible to me (with eyeballs used to look at basic second order ringing oscillators).

Eagleworks inverted torsional pendulum response to exponentially decaying forcing functions (force in Newtons)

  Rodal 2014  :)


Piecewise[{{(80*10^(-6))*(1-Exp[-t/tau]),t<30},{0,t>= 30}}],tau=0,0.5,1,2,3

Piecewise[{{(80*10^(-6))*(1-Exp[-t/tau]),t<30},{(80*10^(-6))*(Exp[-(t-30)/tau]),t>= 30}}],tau=0,0.5,1,2,3

Piecewise[{{(80*10^(-6))*(1-Exp[-t/tau]),t<30},{(80*10^(-6))*(Exp[-(t-30)/tau]),t>= 30}}],tau=2
« Last Edit: 10/28/2014 06:42 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #2750 on: 10/28/2014 06:33 PM »
I want to thank and recognize in public, aero, who sent me the following message noticing that there is yet another formula to calculate the thrust:



Dr. Rodal,

The Chinese paper gives this formula for thrust. ..Fe and Fm are the electrical and magnetic field forces and the subscripts are 1-big, 2-small, 3-sidewall.

Fa=Q[∫A1 (Fe1+Fm1)dA-∫A2 (fe2+fm2)dA -∫A3 (Fe3+Fm3)cosθdA)] (13)

(Equation 13 is on page 6 of the translated 2010 paper. http://www.emdrive.com/NWPU2010translation.pdf
Journal of Northwestern Polytechnical University Vol 28 No 6 Dec 2010, Applying Method of Reference 2 to Effectively Calculating Performance of Microwave Radiation Thruster, Yang Juan,Yang Le,Zhu Yu,Ma Nan
(College of Astronautics,Northwestern Polytechnical University,Xi′an 710072,China) )

where Fe and Fm are normal to the cavity surface, pointing inward,
and
The amount of force is |Fe|=1/2eoE^2
The amount of force is |Fm|=1/2uoH^2

Note that Q does already appear in the force equation (13) above.

aero
« Last Edit: 10/28/2014 06:36 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #2751 on: 10/28/2014 08:30 PM »
...
Sorry, I re-checked the code because that statement about the 7 sec didn't make sense to me and I found an error on my definition of the exponential function (I had the variable "time" instead of "t" which mean different things in my code.  I'll be back with the correct result

Yes, any tau>0.2 sec is clearly discernable.

For tau ~ 1 sec the difference is unacceptable

I'll post some pictures tomorrow after I double check everything.   I need to do some work for which I get real $$$ first  :)

All right. I'm a bit surprised then. Maybe not 7s but 2s seemed like possible to me (with eyeballs used to look at basic second order ringing oscillators).

Eagleworks inverted torsional pendulum response to exponentially decaying forcing functions (force in Newtons)

  Rodal 2014  :)

The previous plots showed the torsional angular motion due those purely torsional forcing functions .

It is interesting to look at the chaotic motion of the swinging angular motion of the pendulum for the lower moment of inertia motion, due to coupled nonlinearity for the following case:

Forcing function for torsional force:
Piecewise[{{(80*10^(-6))*(1-Exp[-t/tau]),t<30},{0,t>= 30}}],tau=0.000001

Forcing function for swinging force excitation (lower moment of inertia angular direction)
Piecewise[{{(80*10^(-6))*(1-Exp[-t/tau]),t<30},{(80*10^(-6))*(Exp[-(t-30)/tau]),t>= 30}}],tau=0.000001

NOTE: the amplitude is about 1% of the previous motion, so the chaotic motion is not noticeable for this forcing function during this time period.  Notice that the chaotic motion persists long after the forcing excitation has died out: a chaotic artifact due to the nonlinear equations of motion  , nothing to do with the excitation. 

That's the problem with inverted pendulum, and that's why I have criticized the use of inverted pendulums instead of a classical Cavendish set-up as used to measure the inverse square law of gravitation and as used by Brito et.al  But again, for this forcing function: so far not noticeable.

« Last Edit: 10/28/2014 08:40 PM by Rodal »

Offline Ron Stahl

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Re: EM Drive Developments
« Reply #2752 on: 10/28/2014 08:43 PM »
I'm not following what you're calling "chaotic".  What's the period period of this beam?

Offline aero

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Re: EM Drive Developments
« Reply #2753 on: 10/28/2014 08:49 PM »
@ Dr. Rodel - You're Welcome.

With the right choice of resonant mode frequency the standing wave within the cavity results in unbalanced axial pressure giving thrust to the cavity, via the equation from the Chinese paper. The question still arises,

"Where does the momentum balance?"

Conservation is still very much of interest after all.

We are kind of at the point in sailing ship days where some crewman tied his sleeping roll to his oar, held it up and told his buddies, "Look, if I hold the corners with my feet I don't have to paddle!!"

That was long before tall ships with area ruled hulls and Bermuda rigged masts.
« Last Edit: 10/28/2014 08:56 PM by aero »
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Offline Rodal

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Re: EM Drive Developments
« Reply #2754 on: 10/28/2014 09:10 PM »
@ Dr. Rodel - You're Welcome.

With the right choice of resonant mode frequency the standing wave within the cavity results in unbalanced axial pressure giving thrust to the cavity, via the equation from the Chinese paper. The question still arises,

"Where does the momentum balance?"

Conservation is still very much of interest after all.

We are kind of at the point in sailing ship days where some crewman tied his sleeping roll to his oar, held it up and told his buddies, "Look, if I hold the corners with my feet I don't have to paddle!!"

That was long before tall ships with area ruled hulls and sloop rigged masts.


1) None, absolutely none of the researchers have actually measured linear acceleration of the center of mass of the system under measurement.  No discussion of conservation of momentum is really an issue until somebody does.  The ideal test would be for a free-free body, as done by the Wright brothers, Goddard, even the Gossamer Albatros, and the recent demonstration of the man-powered helicopter (which was considered impossible until recently).

2) NASA Eagleworks, the Chinese, Cannae, and Shawyer (except his demo) have made measurements on constrained systems.  None of the researchers have analyzed their measurement systems to analyze whether indeed conservation of momentum is being violated.  The closest experiment to a violation of conservation of momentum is Shawyer's demo experiment, but again, the EM Drive demo is restrained and the whole setup is rotating instead of linearly accelerating.  No linear acceleration of the center of mass was measured and the measurement system was not analyzed.

If an astronaut inside a spacecraft puts a sensor on a wall of a spacecraft and then takes a big hammer and hits the wall of the spacecraft, he will measure dynamic motion of the wall of the spacecraft.  That doesn't mean that conservation of momentum was violated.  In that experiment the center of mass of the whole system (astronaut, hammer and walls) did not experience any acceleration due to the astronauts hammering the wall.  However, the wall did move and it had a noticeable dynamic response.

Discussions of violation of conservation of momentum are premature until an experimenter shows that the center of mass of the whole system experienced an acceleration response either by flying the object unrestrained (free-free) or they properly analyze the measurement system - which nobody has done.
« Last Edit: 10/28/2014 09:35 PM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2755 on: 10/28/2014 09:46 PM »
@ Dr. Rodel - You're Welcome.

With the right choice of resonant mode frequency the standing wave within the cavity results in unbalanced axial pressure giving thrust to the cavity, via the equation from the Chinese paper. The question still arises,

"Where does the momentum balance?"

Conservation is still very much of interest after all.

We are kind of at the point in sailing ship days where some crewman tied his sleeping roll to his oar, held it up and told his buddies, "Look, if I hold the corners with my feet I don't have to paddle!!"

That was long before tall ships with area ruled hulls and sloop rigged masts.


1) None, absolutely none of the researchers have actually measured linear acceleration of the center of mass of the system under measurement.  No discussion of conservation of momentum is really an issue until somebody does.  The ideal test would be for a free-free body, as done by the Wright brothers, Goddard, even the Gossamer Albatros, and the recent demonstration of the man-powered helicopter (which was considered impossible until recently).

2) NASA Eagleworks, the Chinese, Cannae, and Shawyer (except his demo) have made measurements on constrained systems.  None of the researchers have analyzed their measurement systems to analyze whether indeed conservation of momentum is being violated.  The closest experiment to a violation of conservation of momentum is Shawyer's demo experiment, but again, the EM Drive demo is restrained and the whole setup is rotating instead of linearly accelerating.  No linear acceleration of the center of mass was measured and the measurement system was not analyzed.

If an astronaut inside a spacecraft puts a sensor on a wall of a spacecraft and then takes a big hammer and hits the wall of the spacecraft, he will measure dynamic motion of the wall of the spacecraft.  That doesn't mean that conservation of momentum was violated.  In that experiment the center of mass of the whole system (astronaut, hammer and walls) did not experience any acceleration due to the astronauts hammering the wall.  However, the wall did move and it had a noticeable dynamic response.

Discussions of violation of conservation of momentum are premature until an experimenter shows that the center of mass of the whole system experienced an acceleration response either by flying the object unrestrained (free-free) or they properly analyze the measurement system - which nobody has done.

Gtocha - Though Shawyer's Demonstrator test on the turntable looks suspiciously like motion ... That is a data sample of one and we have enough trouble with a data sample of seven.
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Offline Ron Stahl

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Re: EM Drive Developments
« Reply #2756 on: 10/28/2014 10:13 PM »
Shawyer made an explanation years ago about how the thruster would develop less and less thrust the faster it was going, but the mechanism made no sense, and it still proposed to violate conservation, and the whole notion of velocity changing thrust is again, a violation of relativity.  Velocity relative to what exactly?  Made no sense and that was just before they cut his funding in Great Britain, IIRC. 
« Last Edit: 10/28/2014 10:13 PM by Ron Stahl »

Offline aero

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Re: EM Drive Developments
« Reply #2757 on: 10/28/2014 10:36 PM »
Shawyer made an explanation years ago about how the thruster would develop less and less thrust the faster it was going, but the mechanism made no sense, and it still proposed to violate conservation, and the whole notion of velocity changing thrust is again, a violation of relativity.  Velocity relative to what exactly? ...snip...

I agree with that. His explanation seemed to me to require the thruster to remember the reference frame at the time of "Power on" and limit itself to accelerations that conserved everything. Maybe he was saying something else but if so, it was very obscure to me.

I don't know about his funding.
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Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2758 on: 10/29/2014 12:08 AM »
There is no explicit mating shown in the referenced picture (reproduced below), and again you are considering the lip from only  one side.

Not quite sure I unnerstand ya, doc.  Here's my guess as to what the section thru the completely fabricated round thing is.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #2759 on: 10/29/2014 12:18 AM »
There is no explicit mating shown in the referenced picture (reproduced below), and again you are considering the lip from only  one side.

Not quite sure I unnerstand ya, doc.  Here's my guess as to what the section thru the completely fabricated round thing is.

So I reckon that  you came up with the same cavity height: 3 cm (three centimeters), partner

« Last Edit: 10/29/2014 12:34 AM by Rodal »

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