Author Topic: EM Drive Developments Thread 1  (Read 780999 times)

Online Mulletron

  • Full Member
  • ****
  • Posts: 1116
  • Liked: 779
  • Likes Given: 1029
Re: EM Drive Developments
« Reply #1620 on: 10/06/2014 06:18 PM »
...

The dummy load was inside! Processing.......

Okay It wasn't elucidated that I can see, but in order to derive the  9.6 micronewton null force, you would have to take into account the thrust from the test article first, subtract the thrust (if any from the dummy load, which takes into account a lot of variables, including non linearaties of the heat produced by the dummy load itself coupled with the geometry of the test chamber. AND this is assuming the dummy load impulse effects were less than the test article, otherwise the dummy load's heat offload would dominate the impulse measured and it would appear thrust is happening, but they got the sign wrong...........(amiright?).You know what? This all sounds like BS because 1, we don't have enough info and 2 the effects are way small. I'm about to abandon this level of critical analysis of the paper because there are way too many assumptions based on too little info. The emdrive's supposed thrust is so close to the noise floor, that this way of analyzing it is not effective. We're gonna have to wait and see what other people do.
Well, these are some of the reasons why I have been bringing this up.  But there are more,  there are also magneto-thermo mechanical and dynamic aspects to this coupling as well.  That is why the classical set-up of Cavendish has been used to measure gravitational inverse-square law and the Casimir force in classical experiments and that's why Brito et al used a Cavendish type of setup with oil damping that falsified their inverted flexure beam experiments. 

I understand why Dr. White's team went this way: they wanted to have the setup to be small enough to fit inside their vacuum chamber.  This is the inverted pendulum they had. They did not have access to one as for example designed by Prof. Martinez-Sanchez at MIT to eliminate mode coupling between swinging and torsional modes.

Fine, we have to live with this: these are the experimental results we have and we need to take these issues into account in order to assess their validity.  So, we continue as we have been doing, we have made a lot of progress in analyzing this, and we should continue.

So, Ron's comments and answers concerning Mulletron's and my questions would still be appreciated, because the better we understand this coupling the better we can assess the significance of the results.

I need to walk away from this for a while. I need to revisit the actual paper which I marked up with notes very early on, because it isn't fresh in my mind anymore and I have new insights to apply. I need to digest and reflect and give time for others to do the same.....
Challenge your preconceptions, or they will challenge you. - Velik

Offline aero

  • Senior Member
  • *****
  • Posts: 2778
  • 92129
  • Liked: 721
  • Likes Given: 246
Re: EM Drive Developments
« Reply #1621 on: 10/06/2014 06:30 PM »
Guys, you are analyzing EagleWorks' set-up to death. I can understand why we need clean data to see how the force actually behaves with power, frequency, Q, dielectric, ... but don't overlook the fact that Shayer and Ling also claim results. I don't know their test set-ups but I doubt that the error modes were common to the EagleWorks set-up.

In other words, "Don't lose sight of the forest for the trees!" :)
Retired, working interesting problems

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6043
  • Likes Given: 5315
Re: EM Drive Developments
« Reply #1622 on: 10/06/2014 07:21 PM »
Guys, you are analyzing EagleWorks' set-up to death. I can understand why we need clean data to see how the force actually behaves with power, frequency, Q, dielectric, ... but don't overlook the fact that Shayer and Ling also claim results. I don't know their test set-ups but I doubt that the error modes were common to the EagleWorks set-up.

In other words, "Don't lose sight of the forest for the trees!" :)

<<Shayer and Ling also claim results. I don't know their test set-ups >>

Hi @aero.  This, in my opinion, is, among Shawyer's papers, the one with the most complete explanation of his experimental setup and results:  http://www.emdrive.com/IAC-08-C4-4-7.pdf
« Last Edit: 10/06/2014 07:21 PM by Rodal »

Offline raketa

  • Full Member
  • **
  • Posts: 216
  • Liked: 37
  • Likes Given: 24
Re: EM Drive Developments
« Reply #1623 on: 10/06/2014 07:26 PM »
I finish book James Woodward: Making Starship and Stargate and it is fascinating book.
1/He is very clearly explaining understanding of our universe base on evolution from Galileo, through Newton and Einstein and recent physicist Feyman, Hawkings. He explains that we are still not able to include influence of gravitation to model of universe.
2/He is revisiting thinking about these troubles and suggests that reason is not understanding of inertia. He is suggesting that inertia is gravitational influence of whole universe on any mass in it. He is also suggesting that electron rest mass could be negative. These 2 ideas first explain, for example how electron could exist at all. The other consequences, that we could temporarily manipulate inertia and get as reaction push from universe gravitation.
3/His theory is very deeply base on the mathematics, I am not able to judge, but it looks like he spend years and years to solve equations used Einstein and others physicist, to include gravity to these description.
4/Base on theoretical finding he was recognizing fact that is probably possible to manipulate inertia and it will be possible even with low budget  to build experiment to confirm his theory.
5/After they build first version they got big feedback, bigger then theory suggest, they spend years and years eliminate outside effect influences.  I think to find flow in their experiment will be silly, from afar without knowing detail and participating.
6/James abandon his persuade for 15 years to continue in practical experiments, because he was not able theoretically solve some issue of his theory.
7/Situation change when he find out that equation points to negative rest mass of electron. It was helping explain model of electron and help him to continue on building device to confirm his theory.
Conclusion:
I/His experiment is based on decades theoretical thinking and solving issue of gravity and inertia
II/They diligently work for years try to eliminate all outside influences to their measured thrust
III/His theory will be possible to confirm by experiment compare for example to string theory, that so much people believe, but not possible ever to confirm it by experiment
IV/His approach has strange consequences to time and reality, but in their theoretical approach it is step back to time we believe we are able to theorize and than confirm our theory by experiment, instead of just believing, like for example string theory

Offline Ron Stahl

  • Full Member
  • **
  • Posts: 210
  • Liked: 32
  • Likes Given: 2
Re: EM Drive Developments
« Reply #1624 on: 10/06/2014 07:33 PM »
Yes, but to a much lesser degree, and as I said, it is easy to isolate with a dummy load.  Woodward's thrusters form a perfect dummy load when the phase angle between the 1w and 2w portions of the signal are moved.  At 90* phase thrust is in one direction, and at 270* the other.  At 0* and 180* there is no thrust expected, so the thruster itself makes a perfect dummy load.

Woodward didn't have any coupling with the magnetic dampener.
thanks.

And what specific kind of "Woodward's thruster" was tested by Woodward et.al. with that setup, the MLT or MET type of thruster?
Both.  The MLT's only generate thrusts in the uN's.  The MET's in the mN.  I'd expect the next gen using PMN should produce far more thrust, but unless he's added some thermal stability, it will just be impulses as he sweeps through the resonant frequency, so far less impressive than one would like.  PMN only has its Colossal Dielectric Constant (CDC) of about 20,000 within a 2*k bandwidth, and only that high when it is sintered in a lead oxide atmosphere to avoid the pyrochlore phase of the compound, and I don't think that's how Woodward's stuff was sintered.  So it will be disappointing, but still when within it's thermal bandwidth, far better than the PZT he was using.

Offline JohnFornaro

  • Not an expert
  • Senior Member
  • *****
  • Posts: 9162
  • Delta-t is the salient metric.
  • Planet Eaarth
    • Design / Program Associates
  • Liked: 610
  • Likes Given: 314
Re: EM Drive Developments
« Reply #1625 on: 10/06/2014 07:41 PM »
Sometimes I just flat out don't get it.

Offline Ron Stahl

  • Full Member
  • **
  • Posts: 210
  • Liked: 32
  • Likes Given: 2
Re: EM Drive Developments
« Reply #1626 on: 10/06/2014 07:59 PM »
. . .otherwise the dummy load's heat offload would dominate the impulse measured and it would appear thrust is happening, but they got the sign wrong...........(amiright?)

Sonny does know better than to trust tests sans vacuum.  And really you can't say too much about tests done without except note that thermal contributions are not prompt, and have a slow decay as well.  Still you want to eliminate them, and ion wind and you can't do that without vacuum.

So yeah, I am agreeing with the general sentiment that we can't do too much analysis of a conference paper, when the authors admit they're still in preliminary testing and haven't worked out their protocols yet.  They absolutely have to get the stuff in vacuum.  Once you have thrust in vacuum, then you can start to look more closely.

Too I would note that the noise floor is not that much an issue.  We retrieve signals out of the noise floor all the time.  Ideally yes, you want a signal way above, but there are authentic ways to tease the signal out, given sufficient controls.  And again for this level of mastery you generally want to run continuous, not sweep through a "sweet spot", be it resonance, or thermal or a combination.

With Eagle's funding, they ought to be able to provide all the necessary controls to get conclusive figures.  They are just not there yet, and hence reason to note the differences between conference papers and peer review.  And if NASA is going to go for multiple labs on these issues, seems there are many millions of dollars going into this now.  DARPA first at Eagle but if NASA mobilizes JPL, Stennis and maybe Marshall, we should get some answers.  IMHO, every one of the centers ought to have a lab able to do this sort of work.

After all, is there something MORE important to NASA than developing a Spacedrive?

Offline zen-in

  • Full Member
  • ****
  • Posts: 531
  • California
  • Liked: 468
  • Likes Given: 365
Re: EM Drive Developments
« Reply #1627 on: 10/06/2014 08:02 PM »
A previous lurker and a newly minted member here.   I have been following this topic for some time and just want to throw in a few thoughts I have had, for what they are worth.
 1) The MCL amplifier used is a Class AB amp.   The output, unless it has a DC blocking cap inside the amp, will have a DC offset = Vdd/2.   My guess is the amp does not have a DC blocking cap because that would affect the bandwidth and MCL likes to advertise their amplifiers as being broadband.   It is also possible that different load configurations (reflected power) will change the offset.   When a dummy load is used the RF feedline is totally coaxial so no external magnetic effects would be present.   However when the cavity is loaded the internal loop, if there is a DC offset, would act like an electromagnet.   Any DC magnetic field generated in the loop would not be shielded by the metal.   There is no mention of any testing or mitigation of a DC offset from the Class AB amplifier in the paper.   I would not expect the dual directional couplers used between the amplifier and the cavity to have DC blocking caps.
 2)  I also question the RF theory of this device.   It is an untuned cavity with a very high Q ceramic resonator inside.   Almost all the RF power will be in the ceramic, and very little power will be bouncing off the inside Cu walls of the cavity.   The cavity is just a Faraday cage.   Its end caps are single-sided FR4 (fiberglass PCB material).  The S11 plot (voltage reflection coefficient at the input) shows this very well.   Very, very little RF power is reflected back to the input at 1932.6 MHz.   That is to be expected.  Any RF-tight enclosure with the same ceramic resonator inside would produce a similar S11 plot.   There is no mystery about it.   Well, except where does the anomalous force come from?
 
« Last Edit: 10/06/2014 08:54 PM by zen-in »

Offline Ron Stahl

  • Full Member
  • **
  • Posts: 210
  • Liked: 32
  • Likes Given: 2
Re: EM Drive Developments
« Reply #1628 on: 10/06/2014 08:06 PM »
2/He is revisiting thinking about these troubles and suggests that reason is not understanding of inertia. He is suggesting that inertia is gravitational influence of whole universe on any mass in it. He is also suggesting that electron rest mass could be negative. These 2 ideas first explain, for example how electron could exist at all. The other consequences, that we could temporarily manipulate inertia and get as reaction push from universe gravitation.
It's okay to say this but I just want to point out that what Woodward is saying is that electrons have an undressed negative mass.  This distinction between dressed and undressed is not like between rest and other states of an electron.  He gives the history behind the notion of "dressing" electrons and those chapters (6 & 7?) in the book are amongst the best.  I am extremely impressed with the complexity of the issue and Woodward's ability as per usual to make it crystal clear.  40 years teaching GR will do that for you.

Offline Ron Stahl

  • Full Member
  • **
  • Posts: 210
  • Liked: 32
  • Likes Given: 2
Re: EM Drive Developments
« Reply #1629 on: 10/06/2014 08:11 PM »
I am a little lost because I don't have the paper, but just to clarify: we're here talking about 2 different geometries at once?  The truncated cone/Shawyer resonator is powered AC, but the power supply for the resonator is on the balance arm and it is powered by DC?  And the other device, similarly?  Both have the power supply on the balance arm powered DC and that DC is coupling with the magnetic damping?
« Last Edit: 10/06/2014 08:13 PM by Ron Stahl »

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6043
  • Likes Given: 5315
Re: EM Drive Developments
« Reply #1630 on: 10/06/2014 08:15 PM »
.... for this level of mastery you generally want to run continuous, not sweep through a "sweet spot", be it resonance,...

While I understand that you are here making a general point, I need to clarify that my understanding of the NASA Eagleworks test results is that they were run at fixed constant frequencies during the duration (ranging from 30 seconds to 45 seconds) of the thrust experiments.  They were not frequency sweeps.

Concerning resonance their tests at 1933 MHz and 1937 MHz are very perplexing (see first two rows of table attached below) because the test with a Q factor 2.5 times higher resulted in a thrust force 1/2 as large with practically the same power input and practically the same frequency (0.3% difference).  Such a result flies on the face of a number of theories (including Dr. White's) that predict a higher thrust force proportional to the Q factor (everything else being the same).

Moreover, since these frequencies are only 0.3 % apart this result is very perplexing (and adds to the issues previously discussed regarding  coupling effects).   A 1933 MHz peak does not appear in their S21 plot attached below.  It only shows a 1936 MHz peak. Of course their plot does not have a frequency range detail that would readily show this 0.3% difference but they did not offer any zooming details.  Their S21 plot does not show such a high resonance peak in that region compared with other peak frequencies, either.  Another interesting thing is that their COMSOL prediction is off the most (compared to the actual amplitudes) in this region.  The COMSOL finite element results [shown in the upper part of the picture, with a white background] predicts a much higher resonance in this region that what the S21 [shown with a black background] results show. (The COMSOL finite element results are also off regarding the frequency at which the peak appears, showing the peak occurring at ~1950 MHz)
« Last Edit: 10/06/2014 09:11 PM by Rodal »

Offline RonM

  • Senior Member
  • *****
  • Posts: 2125
  • Atlanta, Georgia USA
  • Liked: 995
  • Likes Given: 777
Re: EM Drive Developments
« Reply #1631 on: 10/06/2014 08:17 PM »
His approach has strange consequences to time and reality, but in their theoretical approach it is step back to time we believe we are able to theorize and than confirm our theory by experiment, instead of just believing, like for example string theory

I'm glad you brought that up. I'm very skeptical about this whole thing, but at least it can be tested. That's a big plus in my book.

Since string theory can't be tested, it is more philosophy than science. Sure it is a logical progression of science and the math is 'beautiful' as mathematicians like to say, but that doesn't mean it is how reality works.

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6043
  • Likes Given: 5315
Re: EM Drive Developments
« Reply #1632 on: 10/06/2014 09:28 PM »
A previous lurker and a newly minted member here.   I have been following this topic for some time and just want to throw in a few thoughts I have had, for what they are worth.
 1) The MCL amplifier used is a Class AB amp.   The output, unless it has a DC blocking cap inside the amp, will have a DC offset = Vdd/2.   My guess is the amp does not have a DC blocking cap because that would affect the bandwidth and MCL likes to advertise their amplifiers as being broadband.   It is also possible that different load configurations (reflected power) will change the offset.   When a dummy load is used the RF feedline is totally coaxial so no external magnetic effects would be present.   However when the cavity is loaded the internal loop, if there is a DC offset, would act like an electromagnet.   Any DC magnetic field generated in the loop would not be shielded by the metal.   There is no mention of any testing or mitigation of a DC offset from the Class AB amplifier in the paper.   I would not expect the dual directional couplers used between the amplifier and the cavity to have DC blocking caps.
 2)  I also question the RF theory of this device.   It is an untuned cavity with a very high Q ceramic resonator inside.   Almost all the RF power will be in the ceramic, and very little power will be bouncing off the inside Cu walls of the cavity.  The cavity is just a Faraday cage.   Its end caps are single-sided FR4 (fiberglass PCB material).  The S11 plot (voltage reflection coefficient at the input) shows this very well.   Very, very little RF power is reflected back to the input at 1932.6 MHz.   That is to be expected.  Any RF-tight enclosure with the same ceramic resonator inside would produce a similar S11 plot.   There is no mystery about it.   Well, except where does the anomalous force come from?
 

WELCOME to the forum.  Great post.

The S11 plot you are referring to is this one I attach below, is that right? (I want people without immediate access to the report to see it here).  In my report the resolution for this plot is very low, so even if I magnify it, it is very difficult to ascertain the frequency.  (The S21 plot, by comparison is much larger and easier to read).  We can tell the Q=7320, and therefore from the text, ascertain the frequency (1932.6 MHz).
« Last Edit: 10/06/2014 09:37 PM by Rodal »

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6043
  • Likes Given: 5315
Re: EM Drive Developments
« Reply #1633 on: 10/06/2014 09:43 PM »

 1) The MCL amplifier used is a Class AB amp.   The output, unless it has a DC blocking cap inside the amp, will have a DC offset = Vdd/2.   My guess is the amp does not have a DC blocking cap because that would affect the bandwidth and MCL likes to advertise their amplifiers as being broadband.   It is also possible that different load configurations (reflected power) will change the offset.  When a dummy load is used the RF feedline is totally coaxial so no external magnetic effects would be present.   However when the cavity is loaded the internal loop, if there is a DC offset, would act like an electromagnet.   Any DC magnetic field generated in the loop would not be shielded by the metal.   There is no mention of any testing or mitigation of a DC offset from the Class AB amplifier in the paper.  I would not expect the dual directional couplers used between the amplifier and the cavity to have DC blocking caps...
So, if I understand you correctly you agree that the internal loop will act as an electromagnet, and the DC magnetic field will NOT be shielded by the metal. [I would add that any slowly-varying components of the magnetic field will not be shielded either]

We also know that they are using three Neodymium (NdFeB Grade N42) block magnets and they know they have an interaction from the magnetic damper responsible for an acknowledged ~10 microNewton measured artifact and a changing baseline. 

(They blame this as resulting from coupling between the magnetic damper and the power cable, though:

<<This current causes the power cable to generate a magnetic field that interacts with the torsion pendulum magnetic damper system.>> p.14

)

Therefore, there could be an interaction between the DC magnetic field escaping the device, interacting with the magnetic damping field and producing a spurious thrust force that maybe an artifact rather than real thrust ?

In other words, if it is a magnetic artifact, this thing would not propel itself in outer space?
« Last Edit: 10/06/2014 11:26 PM by Rodal »

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6043
  • Likes Given: 5315
Re: EM Drive Developments
« Reply #1634 on: 10/06/2014 09:50 PM »
... I also question the RF theory of this device.   It is an untuned cavity with a very high Q ceramic resonator inside.   Almost all the RF power will be in the ceramic, and very little power will be bouncing off the inside Cu walls of the cavity.   The cavity is just a Faraday cage.  ...
 
Although several of us have come to a similar conclusion, I would like to explore your reasoning a little further.

How do you know that it has a very high Q resonator inside?  (Is it because when they remove it they measure no thrust force?)

How do you know that the resonator is a ceramic?  The report mentions a PTFE ("Teflon") dielectric resonator (albeit for the Cannae device if my memory serves me correctly).  Did I miss the "ceramic" information in the report somewhere. Is this information from another report?

Thank you again for your great post  :)
« Last Edit: 10/06/2014 09:57 PM by Rodal »

Offline Rodal

  • Senior Member
  • *****
  • Posts: 5895
  • USA
  • Liked: 6043
  • Likes Given: 5315
Re: EM Drive Developments
« Reply #1635 on: 10/06/2014 09:53 PM »
...   Its end caps are single-sided FR4 (fiberglass PCB material). ...

OK, this is great information, but I must ask, how do you know that it is single-sided PCB material? Is that in the report?  Is it from your experience? Is it from another report?

How do we know that there is no copper plate behind the PCB material?

Thanks again  :) great to have you here
« Last Edit: 10/06/2014 11:28 PM by Rodal »

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
Re: EM Drive Developments
« Reply #1636 on: 10/06/2014 09:55 PM »
I am a little lost because I don't have the paper, but just to clarify: we're here talking about 2 different geometries at once?  The truncated cone/Shawyer resonator is powered AC, but the power supply for the resonator is on the balance arm and it is powered by DC?  And the other device, similarly?  Both have the power supply on the balance arm powered DC and that DC is coupling with the magnetic damping?

I guess it is about zen-in (Welcome) post ?
If I understood anything at all, I would say yes. The coupling of the DC from lab to "onboard" RF generator is explicitly taken into account by being evaluated with dummy load, then subtracted (albeit "linearly" at the great despair of dr Rodal...)

By AC you mean RF (GHz) don't you ? It wasn't clear in one of your previous post, AC vs DC, Woodward's  devices don't use a modulation of the RF signal, do they ?

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
Re: EM Drive Developments
« Reply #1637 on: 10/06/2014 10:03 PM »
...regardless of the dielectric's acoustic geometry, M-E physics cannot explain thrust from a DC signal.  It can explain thrust impulses from switching transients, and AC signals, but not DC.  You've been reading the paper recently so you should be able to tell more easily than I whether the setup meets the criteria to be acting as a MET....

This is very useful information, thank you.  Could you be so kind as to review the following excerpt from the NASA Eagleworks report and let us know your opinion of whether "M-E physics" can explain thrust from the following signal:

p.8 <<During testing, the Test Engineer controls the RF frequency generation via a 0-to-28 volts dc power input to a voltage-controlled oscillator (VCO). The VCO RF signal output is passed to a variable voltage attenuator (VVA), the output of which is controlled by the Test Engineer via a 0-to-17 volts dc power input. Based upon the VVA output, the amplifier will output up to approximately 28 watts. Amplifier output passes to a dual-directional coupler (DDC), which allows forward and reflected power measurements to be obtained as the power is simultaneously passed to the test article input port. The Test Engineer monitors forward and reflected power and adjusts the input frequency to obtain the desired combination of cavity frequency and power delivery to the cavity.>>
It's DC, so M-E theory cannot explain constant thrust from such a setup unless there is significant ripple in the signal.  There's no data about ripple here.  M-E theory could explain thrust form switching transients here.  Did this experiment generate constant thrust or thrust impulses during switching?

There, what DC are you talking about ? You mean DC like in a 9V battery, or RF power at 1GHz but constant (unmodulated) ? And if modulated, how should it be modulated, in amplitude, at what freq, what shape ?

Offline Ron Stahl

  • Full Member
  • **
  • Posts: 210
  • Liked: 32
  • Likes Given: 2
Re: EM Drive Developments
« Reply #1638 on: 10/06/2014 10:34 PM »
It wasn't clear in one of your previous post, AC vs DC, Woodward's  devices don't use a modulation of the RF signal, do they
They haven't in the past though they may in the future.  There is reason to suppose interrupting the AC into a pulsed AC signal could significantly enhance the thrust, and this is the subject of Jim's latest patent app.

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
Re: EM Drive Developments
« Reply #1639 on: 10/06/2014 10:35 PM »
I would say, assuming it's possible at all to "burn" DM mass into energy, a few % of c, but with unlimited delta V (since feeding on the way)

At least I get the Bussard ramjet idea.  More or less, you don't have to carry your "oxidiser", but you do have to carry your "fuel".  I think.

Not for a Bussard ramjet : incoming mass is the energy, because you fly in a (diluted) gas of light nuclei that has still punch in it to be released when fused. You could do it also in a diluted gas of heavy nuclei (mmm, diluted gas of thorium). But not in a diluted gaz of iron 56. It's like flying in a fuel/oxidiser mixture, only a fuel oxidiser mix is unstable long term, while light nuclei needs special conditions to release their potential (energy) and are otherwise quite stable. But I'm sure you knew that ?

Quote
Quote from: Frobnicat & Mulletron
To be clear : this rectifier effect hypothesis had nothing to do with DM...

No, I got that.  I'm just designing that spacecraft which uses the "rectifier effect hypothesis".  While you don't need an evacuated glass container for the "tube", there would be a lot of mass, and a large size associated with the spacecraft.

Riffing off of caffeine at the moment, I'd guess that you'd need several families of VonNeuman devices, spread out over a large area, fed material some how, and powered, somehow, in order to build the spacecraft.

Which, to my mind, gets back to wondering briefly, on the BOE, how big would that spacecraft have to be?  Both the DM ramjet and the rectifier effect ones.

Well, frankly, for the "rectifier effect" spacecraft, it was a polite way to say the "anomalous thrusts" are spurious measures related to experimental apparatus having a big permanent magnet nearby interfering with some unwanted (and unaccounted for) DC component somewhere. Then you can build as big or small a "rectifier" spaceship you want, as long as another properly driven spaceship is carrying a comparatively big permanent magnet in the vicinity. This would just be a less than efficient tractor beam from tugboat to a free floating hull (a rope being more efficient).

Now if I saw a humongous "rectifier star cruiser" full of guns exiting a wormhole in front of my space limo, I could revise my opinion.

Tags: