Author Topic: Propellantless Field Propulsion and application  (Read 664849 times)

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1720 on: 11/14/2012 04:04 PM »
No one cares about the thrust measurement device. ... If a particular mechanism is needed to measure the thrust then the results are bogus.

You did read what you wrote, I trust.

Note that neither the EM drive device, nor the thrust measurement device, at this writing, are subject to peer review.
« Last Edit: 11/14/2012 04:04 PM by JohnFornaro »
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Offline aero

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Re: Propellantless Field Propulsion and application
« Reply #1721 on: 11/14/2012 04:26 PM »
No one cares about the thrust measurement device. ... If a particular mechanism is needed to measure the thrust then the results are bogus.

You did read what you wrote, I trust.

Note that neither the EM drive device, nor the thrust measurement device, at this writing, are subject to peer review.

John - You're grasping at straws. The topic is Propellantless Field Propulsion and application. The test stand has no bearing on the topic beyond giving assurances that the thrust measurements were accurately made. Any good test stand will do, even a pendulum.
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Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1722 on: 11/14/2012 05:11 PM »
John - You're grasping at straws. The topic is Propellantless Field Propulsion and application. The test stand has no bearing on the topic beyond giving assurances that the thrust measurements were accurately made. Any good test stand will do, even a pendulum.

Aero:  I'm not grasping at anything.  As you may have noticed, I'm not trying to prove anything.  The experimental protocol here does not seem to be subject to peer review.  Are you saying that it is?  And you are totally satisfied with the paper?  And that the results of this invention are accurate as reported?  I'd ask, to the point of investing in it?  Which of course, I wouldn't ask.  Meh. 

The common wisdom is that EM drive does not work.  In the case of Woodward's work, and probably Shawyer's as well, the test stand is almost as important as the tested device itself, since the expected forces are thought to be very low in the experiments demonstrated.

Woodward and Paul March have gone to great lengths to account for spurious outside signals, and even now, can barely ascertain the output of his device from noise.

A pendulum will most assuredly not work.  Either dig up the thread to find out for yourself about some of these particulars, or take my word for it.  The measurement of the forces is key, until such time as they float one of these devices out on the conference room table.

In my opinion, the measurements of this group cannot be taken at face value and cannot even be checked.  YM, as they say, MV.
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Offline aero

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Re: Propellantless Field Propulsion and application
« Reply #1723 on: 11/14/2012 07:09 PM »
720 mN is 2.6 oz-force. That is small but a real world level of force. It takes nothing special to measure it. It is 3 to 5 orders of magnitude larger than the forces that Woodward and Paul March have gone to great lengths to work with and measure accurately.

Do I think the EMdrive works? I have no opinion on that - see my posted theory about a page up-thread for an idea of what I think of the EMdrive explainations.

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Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1724 on: 11/15/2012 02:20 PM »
720 mN is 2.6 oz-force. That is small but a real world level of force. It takes nothing special to measure it. It is 3 to 5 orders of magnitude larger than the forces that Woodward and Paul March have gone to great lengths to work with and measure accurately.

Well, I gotta say that I completely overlooked the scale of the force here, and got stuck in underestimating it, therefore thinking their measurement device was to be questioned.  My bad.
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Offline aero

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Re: Propellantless Field Propulsion and application
« Reply #1725 on: 11/15/2012 03:12 PM »

Quote
Well, I gotta say that I completely overlooked the scale of the force here, ...

Now that we're on the same page I must say that it is the magnitude of the EMdrive thrust that makes me both interested and skeptical. But thrust is large enough and the EMdrive appears to be simple enough that it could be confirmed by a highschool science level experiment. It utilizes components available in a comon household microwave oven so might possibly be built is a garage. I don't know but the devil is always in the details ...

Really, though, the device doesn't seem any more complex that a fusor and there are a lot of bright people at fuzor.org buillding those devices. Maybe some bright kid will start a web page, EMdrive.org, and we'll start hearing rumors about further test results.

As for my theory about how it works, I ended by guessing that the massive bosons tunnel into the Quantum foam. That is not necessary. The same thrust result could be achieved if the massive bosons dissipated while moving in a preferred direction( due to the shape of the device perhaps), and making a Bose-Einstein condensate dissipate is really easy. Making it dissipate while traveling in a preferred direction would be the trick.
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Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1726 on: 11/15/2012 04:26 PM »
...making a Bose-Einstein condensate dissipate is really easy...

In high school? 

About scale.  Micro, milli, whatevs...
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Offline aero

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Re: Propellantless Field Propulsion and application
« Reply #1727 on: 11/15/2012 04:32 PM »
...making a Bose-Einstein condensate dissipate is really easy...

In high school? 

About scale.  Micro, milli, whatevs...

Yes. Creating a Bose-Einstein condensate has been hard (until now?) but letting it dissipate is really, really easy. In fact, so easy that avoiding dissipation is the problem.

Scale. You know this - 10^-6, 10^-3, 1 newton = 0.1019716213 kilogram-force
« Last Edit: 11/15/2012 04:38 PM by aero »
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Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1728 on: 11/15/2012 05:17 PM »
Scale. You know this ...

Just sayin'... I'm constantly dropping/adding zeros.  A cross I have to bear...
Sometimes I just flat out don't get it.

Online QuantumG

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Re: Propellantless Field Propulsion and application
« Reply #1729 on: 11/15/2012 07:39 PM »
thrust is large enough and the EMdrive appears to be simple enough that it could be confirmed by a highschool science level experiment. It utilizes components available in a comon household microwave oven so might possibly be built is a garage. I don't know but the devil is always in the details ...

Is there a document somewhere detailing the dimensions of a drive that has actually worked? So far as I can tell, everyone reporting success has failed to provide even that trivial level of detail.


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?

Offline aero

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Re: Propellantless Field Propulsion and application
« Reply #1730 on: 11/15/2012 09:47 PM »
thrust is large enough and the EMdrive appears to be simple enough that it could be confirmed by a highschool science level experiment. It utilizes components available in a comon household microwave oven so might possibly be built is a garage. I don't know but the devil is always in the details ...

Is there a document somewhere detailing the dimensions of a drive that has actually worked? So far as I can tell, everyone reporting success has failed to provide even that trivial level of detail.




http://www.emdrive.com/NWPU2010translation.pdf

Quote
In the conical microwave thrusters in Figure 1, the radiated microwave produce
three forces normal to the axes of the front, back end and its side, Fs1, Fs2 and
Fs3, the net thrust obtained by the thrusters along the axes are
Fa=Fa1-Fa2-Fa3cosθ. In order to obtain the largest thrust, the design of the
cavity requires Fa1/Fa2 to be the largest, Fa3/Fa1 to be the smallest, so
Fa≈Fa1-Fa2.

The paper didn't give dimensions, but does give the relative dimensions. I'm thinking that the microwave frequency (wave length) might define the size of the resonance cavity. The frequency of 2.45 GHz would give a wave length of  12.236 cm.

Edit: WARNING -  Microwave radiation is dangerous, causes cell and eye damage. Microwave radiation can cause cataracts.
« Last Edit: 11/16/2012 01:54 PM by aero »
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Offline Sith

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Re: Propellantless Field Propulsion and application
« Reply #1731 on: 11/17/2012 05:00 PM »
The only thing I regret is that I've been born in the 20th century and that humanity isn't that far yet to stravel between the stars. I hope that before I die I whitness the fistst interstallar human flight in history... Earth need's that for survival.

Online KelvinZero

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Re: Propellantless Field Propulsion and application
« Reply #1732 on: 11/17/2012 11:27 PM »
The only thing I regret is that I've been born in the 20th century and that humanity isn't that far yet to stravel between the stars. I hope that before I die I whitness the fistst interstallar human flight in history... Earth need's that for survival.
I wouldn't worry about it. we have hundreds of icy little worlds right here. Consider Albiorix, a tiny moon of Saturn way down that list, a mere 16km in radius. That translates to a 100km circumference.
These will actually be much easier to colonize than earthlike worlds. If our moon was another earth (pre life, or with incompatible life) I don't know if we would even have managed apollo yet. It wouldnt support  earth life, might actively repel it, and it would be incredibly hard to bring anyone back.
« Last Edit: 11/17/2012 11:47 PM by KelvinZero »

Offline aceshigh

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Re: Propellantless Field Propulsion and application
« Reply #1733 on: 11/18/2012 01:04 AM »
The only thing I regret is that I've been born in the 20th century and that humanity isn't that far yet to stravel between the stars. I hope that before I die I whitness the fistst interstallar human flight in history... Earth need's that for survival.

if you had been born in the future, you would regret you had not been born even further in time, to be able to travel between galaxies, whatever.

just 100 years ago people could barely fly at all.

anyway, immortality or at least life spans of 500 years or more are "almost" within our grasp. Scientists predict the first person that will live 150 years old is alive and is already 50 years old right now.

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1734 on: 11/19/2012 02:05 PM »
Scientists predict the first person that will live 150 years old is alive and is already 50 years old right now.

Dang.  I missed that opportunity almost ten years ago...
Sometimes I just flat out don't get it.

Offline Afrocle

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Re: Propellantless Field Propulsion and application
« Reply #1735 on: 12/03/2012 01:55 PM »
I have not seen a discussion of how the propellantless EMDrive could work using radiation pressure as discussed within the recent Chinese paper.

The Chinese paper states that this propellantless drive works like a solar sail. With a solar sail the radiation pressure from the sun is absorbed at 1 AU from the sun at a pressure of 4.6 uN/m2 and is reflected at twice this pressure at 9.15 uN/m2. The sun has a power flux density of 1.37 kw/m2 at 1AU.

The scale of these solar sail radiation pressures appear to be 100,000 times higher than the EMDrive propulsive force at 720 mN for a 2.5-kw power input, but the EMDrive uses a 2.45-Ghz microwave cavity that may have dimensions of 6-cm which is the half wavelength at 2.45-Ghz. Because radiation pressure is equal to one third of the total radiant energy per unit volume within a space, the unit volume of the EMDrive microwave cavity might be 10,000 times less space (i.e. 0.06-meter x 0.06-m x 0.06-m) than a solar sail in open space which may mean that the total radiant energy for EMDrive is 10,000 times higher per unit volume.

This 10,000 times higher radiant energy per unit volume is then absorbed or reflected over smaller surface areas (i.e. 0.06-m x 0.06-m = 0.0036-m2 versus 1-m2) within the microwave cavity which potentially increases the radiation pressure by additional orders of magnitude.

The photons creating the radiation pressure within the microwave cavity are bouncing around in many directions as they are absorbed, reflected, or scattered inside the cavity walls. These photons carry their momentum to these cavity walls in many different directions, and the Chinese paper describes that all of these different force vectors must be shaped and added to provide a net positive thrust in a single desired direction.

As an analogy, this appears to be similar to the first attempts to sail into the wind over a thousand years ago by adding and shaping the then unknown force vectors of aerodynamic lift (Bernoulli's principal) and hydrofoil hydrodynamic forces of a hull in water. These 2 sets of different forces acting on a sail boat had to be shaped and added to sail against the force of the wind, just like the the EMDrive radiation pressure force vectors must be shaped and added to overcome radiation pressure force vectors going in the "wrong" direction within the microwave cavity.

The photons within the microwave cavity have their mass and number increased due to the energy given to them at 2.45-Ghz. The density, number, and combined mass of these photons create a lot more pressure within the confined smaller density of the microwave cavity and the smaller surface areas that the photons are able to strike. If photons are reflected inside the cavity walls, then they can impart their pressure at twice the absorbtion pressure many times before final photon absorption or scatteing, but all of these force vectors must be shaped and added to obtain a net positive thrust in a desired direction.

I would think that there are many people in this forum who understand the principals of propellantless thrust from radiation pressure on a solar sail and who understand what the radiation pressure a 2.5-kw 2.45-Ghz power source could apply on a surface area located 6-cm away from it. I have not seen a discussion within this forum on how the EMDrive could work in this way (as the Chinese paper discusses), and I am sure that many of you understand this much better than I do.

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1736 on: 12/03/2012 02:16 PM »
Then why not just stay with a solar sail? 
Sometimes I just flat out don't get it.

Offline Afrocle

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Re: Propellantless Field Propulsion and application
« Reply #1737 on: 12/03/2012 03:15 PM »
Then why not just stay with a solar sail? 

Because a solar sail can only receive 1.37-kw/m2 at 1 AU from the sun and the inverse sqaure less radiation pressure further from the sun versus the EMDrive restricitng many more KW or MW of onboard power into the confined volume of a 0.06-m x 0.06-m x 0.06-m microwave cavity giving it maybe over 100,000 times more energy per volume and pressure per surface area than a solar sail.

A solar sail absorbs 4 x 10-6 Newtons per m2 so you need a 1,000-meter by 1,000-meter sail (i.e. 1 km2 solar sail for 4 Newtons of pressure absorbtion) to be within the thrust range of an EMDrive which could provide a similar 4 Newtons of thrust with 18-kw of onboard power sent into its small microwave cavity.

Offline douglas100

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Re: Propellantless Field Propulsion and application
« Reply #1738 on: 12/03/2012 03:28 PM »
Quote from Afrocle:

Quote
If photons are reflected inside the cavity walls, then they can impart their pressure at twice the absorbtion pressure many times before final photon absorption or scattering, but all of these force vectors must be shaped and added to obtain a net positive thrust in a desired direction.

You'll be aware that the part I made bold is controversial. Newtonian mechanics suggests that it is not possible to shape the force vectors within the cavity to produce net thrust in a given direction.

On the other hand, John Fornaro has a point: at least we know the solar sail works.
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Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1739 on: 12/03/2012 03:28 PM »
Afrocle:  Have you vetted their math, or are you accepting it?
« Last Edit: 12/03/2012 03:29 PM by JohnFornaro »
Sometimes I just flat out don't get it.

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