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#3460
by
txdrive
on 16 May, 2015 01:39
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Have modified my Shawyer Df calculator and best Df scanner as per the derived Shawyer Df equation, using cutoff wavelength and guide wavelength as per microwave industry supplied equations. I assume Shawyer did not supply these equations in his papers as they are equations that should be known to microwave industry individuals skilled in the art. Anyway they are now in the public record.
The scanner still sweeps the frequency range 0Hz to 10GHz but reports the frequency that generates a Df as close to 1 as possible but not over.
The attached results are very interesting as the frequency needed to get the Df to just below 1 is very close to the Rf driving frequency used to generate Lambda0 or free wavelength in the selected medium.
While I'm still testing the spreadsheet, which meets both of Shawyers boundary conditions, the results for my Flight Thruster design are looking to be very close to what I could build. Bit of dimension tweaking should get the Df 1 frequency to the 3.85GHz Shawyer used.
Will post the spreadsheet after a bit more testing.
I've built and tested many microwave cavities over many years.
You're guided wavelength equation is wrong, because this is for a rectangular wave guide (i.e., not even a rectangular cavity)
You need to derive mode of frequency yourself (unless there is a paper somewhere) for a circular tapered cavity. There is no other way around it. I would start with Balanis - Advanced Engineering Electromagnetics as he derives a few examples for other topologies. Right now everything you are doing is wrong because you don't understand the physics. I would study that book from front to cover if I were you.
Also, to the guy operating the microwave magnetron outside of the microwave: STOP
At best you are violating the laws of your local government's regulatory committee for the electromagnetic spectrum. At worst you will damage your body. At this frequency, the damage is somewhat insidious. Due to low water content of your skin, you don't feel the heat, but internal nerve endings can be damaged so that chronic phantom pain can appear. Sometimes days after exposure. Please STOP otherwise you will inevitably be reported to your government.
The biggest danger, in my understanding, is cooking your eyes. The thermal conductivity is very low and there are no pain receptors.
This thread, the posts some people are making here, have a potential to actually,
physically hurt some people, to cause an irreversible vision loss.
There had been a result of ~50uN from ~2.6 watts. This is a safe power level which can be obtained with low voltage components, and this is a force that should be measurable to sub 1% accuracy (in spite of the heating) with a torsion pendulum consisting of a rod suspended from the ceiling on a metal string, in still air, without requiring an external power feed.
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#3461
by
deltaMass
on 16 May, 2015 01:52
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Yes. And the way to silence sceptics is to make measurements on a fully-boxed rig - including battery. All these trailing feeds generate pseudo-forces. That would be OK if thrust were Newton level - but it ain't, so it ain't.
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#3462
by
A_M_Swallow
on 16 May, 2015 02:42
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Yes. And the way to silence sceptics is to make measurements on a fully-boxed rig - including battery. All these trailing feeds generate pseudo-forces. That would be OK if thrust were Newton level - but it ain't, so it ain't.
The Dynamic Tests of the EM Drive showed a slowly rotating table top of machinery. So sufficient force was being produced to move the equipment 2 metres in a few minutes.
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#3463
by
SeeShells
on 16 May, 2015 02:46
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The search function aren't that super here euuuuu.
Why is the RF injected into the side of the EM Device. I know it's a basic question but can someone expand on it a little more?
Shells
No one else has chimed in, so I'll give this a shot. 
I believe the choice of antenna position is predominantly a function of the antenna beam pattern, and the desire to couple maximum energy into the cavity.
A simple dipole antenna radiates/couples well in the perpendicular direction, so placing a dipole antenna perpendicular to the cavity wall would allow direct coupling into the dominant resonant direction (i.e. between the concave/convex end plates).
(attached image from http://www.trevormarshall.com/byte_articles/byte1.htm)
I had proposed (many pages back) that the use of a waveguide to inject a magnetron's signal had the effect of a directional beam pattern that was much better at injecting energy than removing energy from the cavity. (since resonanting energy is dominantly between the end plates, a waveguide input roughly perpendicular to the walls would inject energy better than remove energy) However, I'll readily admit my reasoning may be overly simplistic.
Thanks,
James
Thanks James!
Know the pattern well and that pattern is in free space, but it makes me wonder sitting in the EM funnel shaped chamber what kind of witches brew of harmonic and sub-harmonic patterns it would make. I've just downloaded some software and I'm going to try my hand at seeing what I end up with.
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#3464
by
Rodal
on 16 May, 2015 03:06
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I am back with an updated draft after some terrible news around about NASA dismissing these researches. They should not as, otherwise, it could happen as with Galilei having his detractors even not trying to look in the telescope, just dismissing on faith.
I have analysed the case of the frustum and the results appear to be striking. One must admit that geometry comes to rescue not just general relativity. For this particular geometry the cavity can be made susceptible to gravitational effects if your choice of the two radii of the cavity is smart enough. This is something to be confirmed yet, just my theoretical result, but shocking anyway.
As usual, any comment is very welcome.
In page 8, equation 34 of http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=830137,
for the integral on dr', should the limits, instead of
0 to ((r2-r1)/h) z' + r2
be
r1 to ((r2-r1)/h) z' + r1 ?
Good Point ! But volume integral ? 0 to ... ((r2-r1)/h) z' + r1 /l0 ? (seems circular that way)
It's Eq. 18 that still bothers me a bit. Invoking the Heaviside step function is OK, but I don't see the addl. components being detectable outside the cavity w/o a non-linear term. Maybe I'm missing something ?
1) Good point about Eq. 18: how do those harmonic components make it outside the cavity? Do they go outside the cavity because of the small transparent portholes on the EM Drive through which the interferometer laser beam is going through?
2) If one wants to nondimensionalize the expression, it would have to be
r1/lo to ((r2-r1)/h) z'/l0 + r1 /l0
instead of
0 to ((r2-r1)/h) z' + r1 /l0
and since
zbar= z/l0
zbar' = z'/l0
then
r1 /l0 to (r2-r1)/h) zbar' + r1 /l0
but the last integral would have to be on drbar' instead of on dr'
and the first integral would have to be on dzbar' instead of on dz,
and the first integral would have to be over
0 to h/lo
instead of
0 to h
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#3465
by
deltaMass
on 16 May, 2015 03:27
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Yes. And the way to silence sceptics is to make measurements on a fully-boxed rig - including battery. All these trailing feeds generate pseudo-forces. That would be OK if thrust were Newton level - but it ain't, so it ain't.
The Dynamic Tests of the EM Drive showed a slowly rotating table top of machinery. So sufficient force was being produced to move the equipment 2 metres in a few minutes.
A constant force produces a constant acceleration, unless you are prepared to abandon Isaac-baby. Where was it? Coupled [sic] with which, the table contained several rotating devices like fans and a hard drive.
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#3466
by
Rodal
on 16 May, 2015 03:42
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Yes. And the way to silence sceptics is to make measurements on a fully-boxed rig - including battery. All these trailing feeds generate pseudo-forces. That would be OK if thrust were Newton level - but it ain't, so it ain't.
The Dynamic Tests of the EM Drive showed a slowly rotating table top of machinery. So sufficient force was being produced to move the equipment 2 metres in a few minutes.
A constant force produces a constant acceleration, unless you are prepared to abandon Isaac-baby. Where was it? Coupled [sic] with which, the table contained several rotating devices like fans and a hard drive.
That's in free-space.
If there was a torsional kinetic friction associated with the bearing, then there was a torque due to that torsional kinetic friction, and therefore there was a force (times the radius) associated with that kinetic friction, under constant velocity.
The force due to kinetic friction could be roughly (pun intended) constant for dry friction at constant velocity, if the force being exerted was just enough to balance the kinetic friction.
Even a fluid bearing will have a force due to the viscosity of the fluid.
Or it could have accelerated.
Who knows? Does anybody have a displacement vs. time trace for that test in the YouTube video?
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#3467
by
SeeShells
on 16 May, 2015 03:46
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Yes. And the way to silence sceptics is to make measurements on a fully-boxed rig - including battery. All these trailing feeds generate pseudo-forces. That would be OK if thrust were Newton level - but it ain't, so it ain't.
The Dynamic Tests of the EM Drive showed a slowly rotating table top of machinery. So sufficient force was being produced to move the equipment 2 metres in a few minutes.
A constant force produces a constant acceleration, unless you are prepared to abandon Isaac-baby. Where was it? Coupled [sic] with which, the table contained several rotating devices like fans and a hard drive.
You're right it was with hard drives and fans, but weren't they running before they switched on the EM Drive?
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#3468
by
WarpTech
on 16 May, 2015 03:47
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The competition
http://nextbigfuture.com/2015/05/photonic-laser-thruster-has-moved-one.html
That's what I'm talking about! Something like this would be at least 20% more efficient than an EM Drive could ever be. IMO, no competition...
Todd D.
How do you figure that?
Because, IMO the EM Drive has no thrust without losses. Resonating modes do not exert any NET force. It is the attenuation of evanescent modes that provide whatever thrust can be had.
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#3469
by
SeeShells
on 16 May, 2015 03:56
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#3470
by
deltaMass
on 16 May, 2015 04:04
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#3471
by
deltaMass
on 16 May, 2015 04:06
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Yes. And the way to silence sceptics is to make measurements on a fully-boxed rig - including battery. All these trailing feeds generate pseudo-forces. That would be OK if thrust were Newton level - but it ain't, so it ain't.
The Dynamic Tests of the EM Drive showed a slowly rotating table top of machinery. So sufficient force was being produced to move the equipment 2 metres in a few minutes.
A constant force produces a constant acceleration, unless you are prepared to abandon Isaac-baby. Where was it? Coupled [sic] with which, the table contained several rotating devices like fans and a hard drive.
You're right it was with hard drives and fans, but weren't they running before they switched on the EM Drive?
Excellent point! Unless of course they had clamped the table until the EmDrive was switched on
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#3472
by
Rodal
on 16 May, 2015 04:06
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Anyone seen this little tidbit?
http://phys.org/news/2015-05-newton-law-broken.html
Non-equiibrium thermodynamics
I have to find my old copy of the book by S. R. De Groot, P. Mazur and other such books I have in boxes
and see whether we can derive a force for the EM Drive based on Onsager's relations
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#3473
by
deltaMass
on 16 May, 2015 04:07
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The competition
http://nextbigfuture.com/2015/05/photonic-laser-thruster-has-moved-one.html
That's what I'm talking about! Something like this would be at least 20% more efficient than an EM Drive could ever be. IMO, no competition...
Todd D.
How do you figure that?
Because, IMO the EM Drive has no thrust without losses. Resonating modes do not exert any NET force. It is the attenuation of evanescent modes that provide whatever thrust can be had.
I'm glad someone understands how the EmDrive works!!
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#3474
by
deltaMass
on 16 May, 2015 06:09
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Reading that makes me feel that I've just taken a wrong turn and ended up on the film set of Fear And Loathing In Las Vegas.
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#3475
by
Mulletron
on 16 May, 2015 07:53
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#3476
by
Flyby
on 16 May, 2015 08:08
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I'm glad someone understands how the EmDrive works!!
Does it?
I'm still at the stage that i very much want to believe it, but I don't...
At east, not until someone can produce additional proof it actually moves.
Let's hope that in 2 months time, the people at Eagleworks will be able to share their test results.
Or that any of the homebuilders inhere gets some amazing results to show.
Must say I'm impressed by the preparation and analytical work done by TheTraveller. Let's hope it yields some results...
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#3477
by
StrongGR
on 16 May, 2015 09:37
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I am back with an updated draft after some terrible news around about NASA dismissing these researches. They should not as, otherwise, it could happen as with Galilei having his detractors even not trying to look in the telescope, just dismissing on faith.
I have analysed the case of the frustum and the results appear to be striking. One must admit that geometry comes to rescue not just general relativity. For this particular geometry the cavity can be made susceptible to gravitational effects if your choice of the two radii of the cavity is smart enough. This is something to be confirmed yet, just my theoretical result, but shocking anyway.
As usual, any comment is very welcome.
In page 8, equation 34 of http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=830137,
for the integral on dr', should the limits, instead of
0 to ((r2-r1)/h) z' + r2
be
r1 to ((r2-r1)/h) z' + r1 ?
The choice of the integration limits was done taking into account that if the integrand is 1 I recover the volume of the frustum. However I do not evaluate this integral rather I solve the Poisson equation for L.
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#3478
by
StrongGR
on 16 May, 2015 09:46
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I am back with an updated draft after some terrible news around about NASA dismissing these researches. They should not as, otherwise, it could happen as with Galilei having his detractors even not trying to look in the telescope, just dismissing on faith.
I have analysed the case of the frustum and the results appear to be striking. One must admit that geometry comes to rescue not just general relativity. For this particular geometry the cavity can be made susceptible to gravitational effects if your choice of the two radii of the cavity is smart enough. This is something to be confirmed yet, just my theoretical result, but shocking anyway.
As usual, any comment is very welcome.
In page 8, equation 34 of http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=830137,
for the integral on dr', should the limits, instead of
0 to ((r2-r1)/h) z' + r2
be
r1 to ((r2-r1)/h) z' + r1 ?
Good Point ! But volume integral ? 0 to ... ((r2-r1)/h) z' + r1 /l0 ? (seems circular that way)
It's Eq. 18 that still bothers me a bit. Invoking the Heaviside step function is OK, but I don't see the addl. components being detectable outside the cavity w/o a non-linear term. Maybe I'm missing something ?
That's interesting. The effect of the modified geometry is to couple the resonant mode of the cavity with the external source that in this case is a laser beam. This enters into the correction factor L(v) (sorry for the unfortunate choice of the notation, this is not the same L I use below). I do a first order computation to uncover such a coupling.
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#3479
by
StrongGR
on 16 May, 2015 09:48
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I am back with an updated draft after some terrible news around about NASA dismissing these researches. They should not as, otherwise, it could happen as with Galilei having his detractors even not trying to look in the telescope, just dismissing on faith.
I have analysed the case of the frustum and the results appear to be striking. One must admit that geometry comes to rescue not just general relativity. For this particular geometry the cavity can be made susceptible to gravitational effects if your choice of the two radii of the cavity is smart enough. This is something to be confirmed yet, just my theoretical result, but shocking anyway.
As usual, any comment is very welcome.
In page 8, equation 34 of http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=830137,
for the integral on dr', should the limits, instead of
0 to ((r2-r1)/h) z' + r2
be
r1 to ((r2-r1)/h) z' + r1 ?
Good Point ! But volume integral ? 0 to ... ((r2-r1)/h) z' + r1 /l0 ? (seems circular that way)
It's Eq. 18 that still bothers me a bit. Invoking the Heaviside step function is OK, but I don't see the addl. components being detectable outside the cavity w/o a non-linear term. Maybe I'm missing something ?
1) Good point about Eq. 18: how do those harmonic components make it outside the cavity? Do they go outside the cavity because of the small transparent portholes on the EM Drive through which the interferometer laser beam is going through?
2) If one wants to nondimensionalize the expression, it would have to be
r1/lo to ((r2-r1)/h) z'/l0 + r1 /l0
instead of
0 to ((r2-r1)/h) z' + r1 /l0
and since
zbar= z/l0
zbar' = z'/l0
then
r1 /l0 to (r2-r1)/h) zbar' + r1 /l0
but the last integral would have to be on drbar' instead of on dr'
and the first integral would have to be on dzbar' instead of on dz,
and the first integral would have to be over
0 to h/lo
instead of
0 to h
That's right. All the quantity in the integral should be intended overlined. But this integral is never computed.
