Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2104429 times)

Offline Notsosureofit

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So, before I trundle off to bed...(be'in old an' all)
When we are in the AFR that removes the cavity dispersion at the expense of splitting the frequency into doppler components, and giving us a flat metric tensor, what tensor quantities can we generate which will give zero force in this frame (despite the difference in frequency) and allow us to find the force in the rest frame of the cavity.  Then the question is: can this be done in GR or does it need extensions (such as Sachs-Schwebel, etc)

Offline CW

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Dear Mr. Shawyer, it is very simple. Put your device PLUS power supply on a balance scale, switch it on. If the scale moves (or most preferably in ~vacuum in LEO, kindly ask your chinese friends to arrange for that - they reported almost a Newton "thrust", didn't they), you become an eternally famous person. If it however does not move, stop deluding yourself and others. Deal?
« Last Edit: 01/04/2015 06:58 AM by CW »
Reality is weirder than fiction

Offline QuantumG

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Considering that NASA will fly just about anything of scientific note into space for the cost of the paperwork (and the Ukrainians will fly anything for you for less than $100k) most of these gadgets could be demonstrated in LEO.. if they worked.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Online Req

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ISTM like they may be able to get a clear signal without going all the way into LEO.  Couldn't they send an appropriately sensitive test rig up on a vomit comet or a balloon(then drop it), vacuum chamber included if need be?  1 Newton sounds like a lot with respect to sensitivity/margins/etc in microgravity, so the test rig probably shouldn't need to be terribly complicated or expensive in either case.  At least not when compared to something that's going to LEO and the associated launch/operation costs.
« Last Edit: 01/04/2015 02:52 PM by Req »

Offline Star One

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Considering that NASA will fly just about anything of scientific note into space for the cost of the paperwork (and the Ukrainians will fly anything for you for less than $100k) most of these gadgets could be demonstrated in LEO.. if they worked.

Is this something that could be tested on the outside of ISS?

Online Rodal

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So, before I trundle off to bed...(be'in old an' all)
When we are in the AFR that removes the cavity dispersion at the expense of splitting the frequency into doppler components, and giving us a flat metric tensor, what tensor quantities can we generate which will give zero force in this frame (despite the difference in frequency) and allow us to find the force in the rest frame of the cavity.  Then the question is: can this be done in GR or does it need extensions (such as Sachs-Schwebel, etc)
It would a big surprise if this would be possible within General Relativity: it would certainly go against what Sean M. Carroll and John Baez have stated (particularly concerning frames of reference).  The implication is that extra coupling terms and/or nonlinearities would be needed, such as Sachs-Schwebel.
« Last Edit: 01/04/2015 06:14 PM by Rodal »

Offline Mulletron

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Things are coming together slowly. I have the connectors and pigtails. Got the N-type female bulkhead threaded solder cup connectors and N-type male to SMA male connectors. Also got the panel type bulkhead connectors which I'm familiar with but don't really like, as a backup. I purchased instead of borrowed and shipping costs more than the actual product. The horn antennas in which to couple the rf across the gap will be homebrew (have to make these myself because standard gain horns are way too expensive; this could make it or break it). Copper sheeting is expensive so I didn't just order a bunch of it yet. Mostly because I don't want to waste material, and honestly I'm being lazy (and am still unsure on wasting expendable cash on a failed experiment), and I spent most of my extra cash on Christmas for the kids. Today I finally got around to planning out the frustum configuration and dims. Attached is a screen shot of the cut sheet utilizing a 2x4' sheet. The full CAD is in the google drive link. I can do a light cone (by the base) and a 45 degree (by the apex) with one sheet and have room for cutouts to make the flat ends. The design intent is to provide a cone in which I can quickly change resonant modes by inserting discs of varying diameter. With this setup I can support 2.4ghz ISM band at the narrow end and support 2 full wavelengths plus more in length. 5ghz is also supported.

Tools used:
https://www.google.com/?gws_rd=ssl#q=right%20circular%20cone%20calc%3A%20find%20A_L&skip=s
http://www.analyzemath.com/Geometry_calculators/surface_volume_frustum.html
http://www.calculatorsoup.com/calculators/geometry-solids/conicalfrustum.php
http://www.cleavebooks.co.uk/scol/calsect.htm
http://en.wikipedia.org/wiki/IEEE_802.11#Channels_and_frequencies
http://www.wavelengthcalculator.com/

CAD drawing with cut sheet:
https://drive.google.com/folderview?id=0B4PCfHCM1KYoTXhSUTd5ZDN2WnM&usp=sharing#list

Copper:
http://basiccopper.com/10-mil-copper-sheet-24-x-4-1.html (not cheap)
http://basiccopper.com/24x416milcos.html (might go with thicker, more expensive 16mil.
 
I think 10 mil is the way to go (I'm going for strength enough to support its own weight, but still be lightweight) but before I drop a hunski on it I'm going to get a sampler http://basiccopper.com/samplerpacks.html. I might go with 16 mil http://basiccopper.com/24x416milcos.html. It depends. Here's why I think 10mil or alternate 16mil is the right choice: http://basiccopper.com/thicknessguide.html


« Last Edit: 01/04/2015 05:34 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline aceshigh

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By the way, John Baez (in his blog https://plus.google.com/117663015413546257905/posts/C7vx2G85kr4 , answering correspondence) had some non-flattering things to say about Woodward's approach as well.

which however is not the subject of this thread, as you pointed out at page 2 and 3 of this thread

Quote from: Rodal
As Chris Bergin made clear, the purpose of this forum is to deal with SPACEFLIGHT APPLICATIONS (of EM Drives: those propellantless drives comprised of a microwave cavity as the devices tested by Shawyer in the UK, Prof. Juan Yang in China and Brady, March, White, et.al. at NASA):

Why is this prescription by Chris Bergin being ignored?

Although the latest Woodward experiments (Fearn, Zachar, Woodward & Wanser) show that it takes 20,000 times more power to produce a given level of thrust than the power required to produce the same thrust for the EM Drive (Shawyer demo), and therefore these experiments do not constitute "EM Drive Spaceflight Applications" (as instructed by Chris Bergin) Woodward fans persist on carrying a debate on this thread rather than their own Woodward thread.   

Frankly, I don't understand what is the goal being pursued here by Woodward-effect fans to insist to carry arguments concerning Woodward's theory and experiments in this thread. 

The curtailment of the previous EM Drive thread by this forum's moderator was due to disruptive discussions regarding the validity of the Woodward effect, including a negative review of Woodward's book by a physicist.


seriously Rodal, you chastised us and now posts about Woodward here? Looks like a bait for someone to come defend Woodward theory here...  ::)

if you want to post about Woodward Theory, be it questions, praise, analysis, ARTICLES or CRITICISM, the place is this thread
http://forum.nasaspaceflight.com/index.php?topic=13020.1845

and yes, the article was about EM Drive, but you specifically called out in your comment the criticism by John Baez regarding Woodward Theory, and THAT criticism should be pointed out and discussed in the appropriate thread, as pointed out by yourself in the 2nd and 3rd pages.
« Last Edit: 01/04/2015 05:10 PM by aceshigh »

Offline zen-in

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Good that Shawyer has clarified the force measurement.  Referring to his Fig. 1 from the paper
http://www.emdrive.com/EmDriveForceMeasurement.pdf
and reproduced below, I conclude he is saying the force that is acting on the EM-drive is in the same direction as the vector labeled T.   The only difficulty I have with this is from looking at the videos of the EM=drive.   When it is operating it moves with the small end forward.


In the earlier thread I stated that maybe the thrust was due to heat convection from the sloped sides.   This was dismissed because the EM-drive moves in the opposite direction as seen in the video.


« Last Edit: 01/04/2015 05:14 PM by zen-in »

Offline Mulletron

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I think it is about time for us to get on Eagleworks for an update:

https://www.facebook.com/eagleworksnasa

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

Offline Stormbringer

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@AcesHigh

I think it was because i mentioned Woodward while trying to explain the difference between Vis Vivo forces like electromagnetism, the strong force, weak force and forces that are only apparent when a force or acceleration is applied to a mass such as inertia. such forces are labelled "fictitious" in physics without any negative meaning. everyone realizes there is a such thing as inertia and gravity.

So anyway; i invoked Woodward before Dr Rodal made his reply containing comments on Woodward.
« Last Edit: 01/04/2015 06:29 PM by Stormbringer »
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Online Rodal

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Good that Shawyer has clarified the force measurement.  Referring to his Fig. 1 from the paper
http://www.emdrive.com/EmDriveForceMeasurement.pdf
and reproduced below, I conclude he is saying the force that is acting on the EM-drive is in the same direction as the vector labeled T.   The only difficulty I have with this is from looking at the videos of the EM=drive.   When it is operating it moves with the small end forward.


In the earlier thread I stated that maybe the thrust was due to heat convection from the sloped sides.   This was dismissed because the EM-drive moves in the opposite direction as seen in the video.

Look at Fig. 2 in http://www.emdrive.com/EmDriveForceMeasurement.pdf:

the acceleration according to Shawyer is directed towards the small end, which is entirely consistent with the movement in the video.

Furthermore, Shawyer himself writes that the experiment in the video with the rotary air-bearing with the SPR Demonstrator calculated the force based on measurement of the acceleration (directed towards the small end):

Quote from: Shawyer
It therefore appears that a force measurement can only be made in a dynamic environment, ideally by allowing the thruster to accelerate, measuring that acceleration, and then calculating the thrust from T =   -  Ma. This is not a very easy method, although the SPR Demonstrator Thruster was successfully tested in this way on a rotary air bearing

As discussed by Frobnicat and me in posts above, the definition of the thrust force by Shawyer ( Shawyer defines the thrust force in the opposite direction as to the movement) is highly unorthodox and Shawyer's force arguments are inconsistent, but anyway, as I discuss above, forces can never be measured directly: what can be measured are displacements, strains or accelerations.  The acceleration as defined by Shawyer in Fig. 2 is entirely consistent with the movement in the video.
« Last Edit: 01/04/2015 06:55 PM by Rodal »

Offline Stormbringer

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at the risk of raising the ire or EM thruster purists; this is the time to ask:

only apparent in a dynamic environment, only apparent in excelleration and so forth...

and i noticed that thing i posted in the warp thread thrusts in the opposite direction it should by Newtonian physics. The direction of the induced motion is in the same direction the radiated energy travels. (If I understood it right.)

don't these things kind of resemble "vis inert" or "fictitious" forces?

If not; forgive me, I apparently have that book passage on my mind now, perhaps to uncalled for extremes.
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Offline IslandPlaya

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...and your point is?

Offline Notsosureofit

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Had a couple minutes.  Just thought I'd check the consistency of the dispersion idea against the Greg Egan cavity.  No problem.  It's not a general expression, he has the numeric results for a few modes, but that's enough.

Offline Stormbringer

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...and your point is?
who me? You trying to get me in trouble? ;)

well... I guess it would mean that the EM bit is somewhat misleading. The real mechanism would be from some ordinarily inert and undetectable source that might be non-local or global in nature. He who shall not be named in this thread would suggest the gravitational influence of mostly distant matter. But that is probably far from the only candidate among so called fictitious fields. The EM details, asymmetric capacitors or wobbly cams or whatever was used to create a dynamic environment would only be acting like the small voltage that biases a transistor or the current that pull the contact arm down in a relay. Once you have an *appropriate* dynamic system  the "fictitious" fields would stop pretending to not exist and make themselves known. It would be the aroused dead energy/vis inert that creates the motive force and not necessarily the EM put through the device.

When antigravity is outlawed only outlaws will have antigravity.

Offline IslandPlaya

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Thank you SB. That makes it all as clear as mud.

Offline Stormbringer

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Oh great; then we're both at about the same level of understanding on my ramblings then :)

The references to the effect only being evident when the system was in a dynamic state and others led me to think that that is how inert or dead energies or fictitious energies are described and to speculate that if they sound the same they might be the same. I think it would explain how you can have half a hundred different design approaches that somehow get comparable results. I could go on but I doubt it would be appreciated.
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Offline frobnicat

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ME thrusters are exploring quite a different range of "bulk acceleration" magnitudes (more than 1000s of Gs if I recall, back and forth around the piezos) compared to a freely moving EM drive, horizontally (a few milli Gs ?) or vertically on a scale (1G)... And the "thrusts" (equivalently M times measured a, to deal with recently introduced "special Newtons") should be roughly impacted by a few order of magnitudes less for EM devices than ME devices. That is, if the same "dynamic setting effect" is at play...

Beyond unorthodox pseudo-forces orientation conventions, this "dynamic environment" condition seems quite problematic and ill defined. Ignoring theoretical musings, Shawyer makes 3 phenomenological predictions :
- That a vertical EM thruster on a scale will record no thrust (unless the thruster is efficient enough to fly against 1G)  page 2 "Thus any attempt to measure them by simply placing the thruster vertically on a set of scales will fail"
- That a horizontal EM thruster restrained from accelerating horizontally (through an opposing spring) will record no thrust, page 3 figure 3 "Because the thruster is at rest, no force will be measured on the load cell"
- That a horizontal EM thruster free to move will accelerate horizontally, page 2 figure 2 "In free space, the thruster will simply accelerate at a m/s/s" In this case we are not in free space but on the horizontal axis this is all the same (and claimed results by Shawyer of accelerations on horizontally rotating arms confirm this view from the author)


So if one thing is clear it is that, for him, the definition of "being at rest" is the same whether not moving on a 0G axis (sorry for the ugly wording) as in restrained horizontal situation or not moving in altitude at fixed G pulling, as in vertical situation. Well, maybe that is the common sense most non physicists give to the intuitive concept of "being at rest", but the 2 situations are very different from what equivalence principle would tell : on a horizontal axis a "static object" shows no departure from an inertial rest frame, while on a vertical axis a "static object" (constant altitude) shows an accelerating departure from an inertial rest frame (free falling). Telling the two situations have the same consequence (no differential stressing of springs between device on and off) is either saying that the "effect" does not depend on acceleration relative to inertial rest frames (that is : it is always 0, there is no effect !) or that it breaks equivalence principle.

All right then, equivalence principle is strong but this is not a sacred cow, we can sacrifice it if it's worth. But then there are problems... how can we define "at rest" vs "dynamic environment" in a scientifically sane and quantitatively predictive way as far as measurable quantities are concerned ? Taking the 3 experimental predictions of Shawyer together, certainly not relative to distant matter ( la Machian) since it would depend on local gravity.

Now Shawyer can claim that measuring a 0 net difference on a scale's spring is actually a confirmation of the theory... But if EM drives like to be free, why not just mount the thruster freely in a box, let it accelerate, bump into one end of the box (on a spring) so that the box recoils, and the thruster is free again to accelerate and so on. This cycle would convert "freely accelerating thingy" into net linear momentum, averaged. This box, as seen from outside, could either be itself freely accelerating, or having a net pushing on a spring of a restraining scale as any well behaved thruster is expected to be able to do. Call that a pulsed EM drive.

Offline ChrisWilson68

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Looking over the last several posts, I see absolutely nothing related to space flight applications.  All I see is more of exactly what got the previous version of this thread to disappear for a while.


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