Author Topic: EM Drive Developments - related to space flight applications - Thread 5  (Read 945784 times)

Offline Corlock Striker

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The Frustums vary a bit is size, by mine is 10.2 inches height by 11.01 large diameter and 6.25 small diameter. Is your system capable of this?

As I said previously, the Peachy Printer works by floating liquid resin over salt water.  I did forget to mention how it raised the level of the resin, previously though.  It does this by adding drops of salt water from a secondary container to the build area and passing each drop through a conductive area.  The salt water completes the circuit momentarily and the system knows that a drop of water has passed by.

So, essentially, it works by having two containers of salt water, one higher than the other.  One is your build area, which the liquid resin floats on top of and the laser then cures.  The second is higher than that, and the water drips from that to fill the build area and raise the level of the water in the build area.  You can make the size of these containers whatever you want.  So, yes, the Peachy Printer can handle the size of your Frustum, as long as I have two containers large enough for the water.

Here's a link to the Peachy Printer website.
« Last Edit: 10/28/2015 10:17 PM by Corlock Striker »

Offline rq3

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OK, so Potomac Neuron wrote me back at reddit and I'm having trouble digesting this visual. Perhaps someone here can. He said that the lorentz force will have a vertical component, like a Compass Needle mounted vertically.

I'm at a bit of a duh moment I cannot visualize. Anything to this?
I think it is this: If you have a compass on its side such that N points towards the sky and W points north, then it will rotate itself such that N points north and W points towards the ground. That rotation is on the axis that could make a balance beam tilt, so we would describe the force it's producing as having a vertical component.

The earths field isn't as simple as a bar magnet with a piece of paper over it and iron fillings scattered on it.
Shell
Guess I picked the wrong week to stop sniffing glue (Airplane 1980) but what gives a vertical force to a common compass, which I can only imagine as a horizontal force? Help me shell...  :o

The Earth looks like a huge bar magnet. At a gross level (there are local variations), the magnetic field is parallel to the Earth's surface at the equator, and vertical to the Earth's surface at the poles. Which is why a magnetic compass is useless for polar navigation. The needle wants to point at the center of the Earth.

This effect is known as magnetic dip, or magnetic inclination. High quality compasses (for example, those used in aircraft), are specifically designed for use in particular areas. One buys a compass for northern or southern hemisphere use, and sometimes based upon the latitude of intended use. The higher the latitude, the greater the dip, and the compass is designed to compensate (to a point, no magnetic compass will work at the Earth's poles to indicate direction. At the North Pole, north is down).

Offline zen-in

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...

The Earth looks like a huge bar magnet. At a gross level (there are local variations), the magnetic field is parallel to the Earth's surface at the equator, and vertical to the Earth's surface at the poles. Which is why a magnetic compass is useless for polar navigation. The needle wants to point at the center of the Earth.

This effect is known as magnetic dip, or magnetic inclination. High quality compasses (for example, those used in aircraft), are specifically designed for use in particular areas. One buys a compass for northern or southern hemisphere use, and sometimes based upon the latitude of intended use. The higher the latitude, the greater the dip, and the compass is designed to compensate (to a point, no magnetic compass will work at the Earth's poles to indicate direction. At the North Pole, north is down).

I don't think the geomagnetic field is a strong influence in em-drive measurement error.   The paper recently talked about was concerned with the powerful NIB magnets used to dampen the balance.   The Earth's magnetic field has a field strength of 5X10-5 Tesla.   The force on a current carrying length of wire due to an external magnetic field that is aligned at right angles to it is:
F = BIL,  where I = current in Amps (assume 10 Amps), L = length in meters (assume .01 Meters)
so the resultant force woukd be F = 5X10-5 X 10 X .001  = 5 microNewton.

This is just a rough estimate and on the high side by maybe a factor of 10 but it does give us an idea of how small the effect of the geomagnetic field would be.

And shielding with mumetal will not work.    The magnetic field generated by a current carrying wire just goes into the mumetal where it meets any external magnetic field.   Mumetal shielding only works when the item being shielded, like a Gaussmeter's Hall effect probe, has very small currents flowing through it.
« Last Edit: 10/28/2015 10:00 PM by zen-in »

Offline rfmwguy

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...

The Earth looks like a huge bar magnet. At a gross level (there are local variations), the magnetic field is parallel to the Earth's surface at the equator, and vertical to the Earth's surface at the poles. Which is why a magnetic compass is useless for polar navigation. The needle wants to point at the center of the Earth.

This effect is known as magnetic dip, or magnetic inclination. High quality compasses (for example, those used in aircraft), are specifically designed for use in particular areas. One buys a compass for northern or southern hemisphere use, and sometimes based upon the latitude of intended use. The higher the latitude, the greater the dip, and the compass is designed to compensate (to a point, no magnetic compass will work at the Earth's poles to indicate direction. At the North Pole, north is down).

I don't think the geomagnetic field is a strong influence in em-drive measurement error.   The paper recently talked about was concerned with the powerful NIB magnets used to dampen the balance.   The Earth's magnetic field has a field strength of 5X10-5 Tesla.   The force on a current carrying length of wire due to an external magnetic field that is aligned at right angles to it is:
F = BIL,  where I = current in Amps (assume 10 Amps), L = length in meters (assume .01 Meters)
so the resultant force woukd be F = 5X10-5 X 10 X .001  = 5 microNewton.

This is just a rough estimate and on the high side by maybe a factor of 10 but it does give us an idea of how small the effect of the geomagnetic field would be.

And shielding with mumetal will not work.    The magnetic field generated by a current carrying wire just goes into the mumetal where it meets any external magnetic field.   Mumetal shielding only works when the item being shielded, like a Gaussmeter's Hall effect probe, has very small currents flowing through it.
So really, we should only be concerned about lorentz force if our emdrive effects were below about 10 micronewtons? I think I came to this conclusion months ago, but I've slept since then :)

"We will post our article tomorrow that has the potential to conclude this discussion" - potomac_neuron on reddit.

I really think the author believed this would end the emdrive discussions/testing. I'll let others decide if that's the case. As for me, its off to phase II.

« Last Edit: 10/28/2015 11:13 PM by rfmwguy »

Offline TheTraveller

Resonance does create more heat than no resonance though.  This is very well known and nothing new; it has to do with impedance, power factor, etc.  The short of it is that in the real world, all resonant systems will reach a maximum stored energy where they dissipate energy at the same rate they take energy in, because no system is perfectly resonant in the sense of zero losses.  At resonance, more energy is delivered to the system than if it were off resonance.  Hence more power is dissipated and therefore the system gets hotter.   

So unfortunately, characterizing thermal lift by screwing around with resonance won't work, because thermal lift is itself intimately tied in with resonance.  Change resonance, change thermal lift.   

How much energy can you store in copper frustum of this size with reasonable Q? And how quickly will it reach steady-state? I'm sure when the system is loaded, the heat produced would be the same in resonating and non-resonating cavity, considering the same power is injected.
I don't see how the system would get hotter in resonance assuming the measurement period is long enough.

A microwave cavity doesn't work like that. If the Rf energy is not at the cavities resonance freq, it will not enter the cavity and will be reflected back to the Rf generator.

To protect the Rf gen from the heating effect of the non resonant reflected energy a circulator is placed between the Rf generator and the resonant load which causes the reflected Rf energy to be directed into a heat sink and thermalised. This is standard microwave built tech.

What this means is the frustum will only heat up if the applied Rf energy is at a freq that is inside the frustums resonant bandwidth.

Microwaves, resonant cavities, circulators and even waveguides work in strange ways. Some call it microwave black magic.
It Is Time For The EmDrive To Come Out Of The Shadows

Offline Bob Woods

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.


Offline rfmwguy

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.
Cubesat has a dimensional problem, meaning a 40 cm w x h limit. Most of our stuff is larger. I've read a little about smallsat but don't have enough info. Cubesat does have 40 cm lengths, so if someone comes up with a working model like the Aachen team, it might work.

Still think its too early to plan for space launch, but one can dream big.

Offline VAXHeadroom

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.

They're using 'toysat' builders and have not had good success.  If I build it, you've got a chance it might actually work once it gets to space.  To do that, we'd need a unit that has a max diameter of 20cm (for it to fit into a 12u cubesat).
(Yes, I build satellites for a living... http://tinyurl.com/lcross-is-go )
Emory Stagmer
  Executive Producer, Public Speaker UnTied Music - www.untiedmusic.com

Offline rfmwguy

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.

They're using 'toysat' builders and have not had good success.  If I build it, you've got a chance it might actually work once it gets to space.  To do that, we'd need a unit that has a max diameter of 20cm (for it to fit into a 12u cubesat).
(Yes, I build satellites for a living... http://tinyurl.com/lcross-is-go )
Problem with cubesat is serious power supply for frustum probably cannot fit into dimensions, not to mention the frustum itself. A 40 cm square drives resonant freq up, driving rf source power down. Tried to imagine an inflatable frustum but had a brain tilt.

Offline Bob Woods

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.

They're using 'toysat' builders and have not had good success.  If I build it, you've got a chance it might actually work once it gets to space.  To do that, we'd need a unit that has a max diameter of 20cm (for it to fit into a 12u cubesat).
(Yes, I build satellites for a living... http://tinyurl.com/lcross-is-go )
Problem with cubesat is serious power supply for frustum probably cannot fit into dimensions, not to mention the frustum itself. A 40 cm square drives resonant freq up, driving rf source power down. Tried to imagine an inflatable frustum but had a brain tilt.

Geeze guys, time to innovate.  :D  You've already done things folks have scoffed at, maybe Eagleworks could get you some  extra space.

Wow, I must have struck a nerve ;D 

Then my work is done.

For today.  8)

Offline Bob Woods

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.

Your URL did not wok for me. Can you check it?
You

They're using 'toysat' builders and have not had good success.  If I build it, you've got a chance it might actually work once it gets to space.  To do that, we'd need a unit that has a max diameter of 20cm (for it to fit into a 12u cubesat).
(Yes, I build satellites for a living... http://tinyurl.com/lcross-is-go )

Offline A_M_Swallow

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A basic 1U cubesat is 10 cm X 10 cm X 10 cm. The popular 3U cubesat is 30 cm X 10 cm X 10 cm. Microprocessor and memory boards exist able fit into these container sizes. Solar panels that fold out are also available. A space grade 6U CubeSat SIDE Solar Panel at the Beginning of Life at 80C produces 16.10 W (more at lower temperatures).
http://www.clyde-space.com/cubesat_shop/solar_panels

To take a 40 cm square drive the satellite would have to be made_to_measure (4 X 4 X 1 = 16U).

Offline zellerium

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I think folks should focus on their builds and producing results that can be reproduced rather than focusing on magnetic force interactions.

Next step may be a CubeSat that can be tested near the edges of magnetic interactions in a vacuum and micro-gravity conditions.

Maybe some of you ought to start talking to the Planetary Society.
Cubesat has a dimensional problem, meaning a 40 cm w x h limit. Most of our stuff is larger. I've read a little about smallsat but don't have enough info. Cubesat does have 40 cm lengths, so if someone comes up with a working model like the Aachen team, it might work.

Still think its too early to plan for space launch, but one can dream big.

I've been thinking a lot about a CubeSat and it would be the ideal test, but wouldn't be easy. But maybe you could design a frustum to resonate at Ka band frequencies so that you could downsize it as well as use an off-the-shelf transmitter. Also putting two of them in opposing directions (as someone brought up on an earlier thread) would be the best way to demonstrate thrust. I'd imagine after pumping even just 5 W at resonance into two opposing frustums you'd be able to measure a significant spin eventually. (an hour or so?)

I wouldn't expect to be able to fit a higher power transmitter on a 6u with all other components, plus powering it via solar panels along with rotation measurement, omnidirectional for comms, charging batteries may or may not be feasible.

Unfortunately thermal cycling will be significant and a Cubesat has little ability to control its temperature range compared to larger spacecraft. And I'd guess that the same temperature change would cause a larger change in resonant frequency for a smaller frustum, but thats just a gut feeling.

But I think its possible

My next questions would be:
How long would it take to create an obvious rotation with 5 W injected into dual opposing frustums? (and what rotation could be deemed proof of concept?)
Can a 5 W Ka band transmitter and two smaller frustums fit on a 6u Cubesat with all other necessary components?
Will the transmitter have the frequency range necessary to power the frustum at the temperature extremes?


Offline chavv

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Months ago, maybe in topic-thread 3, the idea of Cubesat was discussed and someone explained that instabilities/unknown environment on these small orbits are too big - quick calculations returned perturbations nearly on scale of N/Kw. Adding the inability to control directly environment or make any changes once the satelite is launched.

Offline TheTraveller

My next questions would be:
How long would it take to create an obvious rotation with 5 W injected into dual opposing frustums? (and what rotation could be deemed proof of concept?)
Can a 5 W Ka band transmitter and two smaller frustums fit on a 6u Cubesat with all other necessary components?
Will the transmitter have the frequency range necessary to power the frustum at the temperature extremes?

Assuming an unloaded Q of 50,000, Df of 0.9 and spherical end plates, 5Ws should generate around 1.5mNs per frustum. Can't share the Rf gen as each frustum will need independent freq tracking. For 2 frustums this project will need 2 duplicate Rf gens and freq tracking.
« Last Edit: 10/29/2015 05:17 AM by TheTraveller »
It Is Time For The EmDrive To Come Out Of The Shadows

Offline A_M_Swallow

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To detect rotation just add cameras to the top and side of the cubesat. We can watch the stars move and use that to calculate the speed of rotation. Small accelerometers are also available.

Offline TheTraveller

To detect rotation just add cameras to the top and side of the cubesat. We can watch the stars move and use that to calculate the speed of rotation. Small accelerometers are also available.

Would need a standard cubesat 3 axis mag torquer to obtain stability before firing up the EMDrives. My youngest son was involved in a multi uni project to design a 2U cubesat. He worked on the command and control system which was in 1 cube that supported additional experiments in the other cube. I got a really good idea how to put a cubesat together and how to control it's orientation.
It Is Time For The EmDrive To Come Out Of The Shadows

Offline TheTraveller

Resonance claims.

On the net is a paper claiming to be an accurate analysis of the EMDrive. As we all know to get Force generation, you must have resonance. So one of the 1st steps in designing an EMDrive is to be able to correctly model what is happening inside the EMDrive so as to be able to calculate the resonance freq.

The attached image is of the frustum design that was modeled for resonance. It has spherical end caps, has a end plate separation of 7.5cm with a big end diameter of 3.52cm and small end diameter of 0.88cm. The small end plate has a radius of 2.5cm and the big end plate has a radius of 10cm. Both radii from the vertex of the frustum. Cone angle is 20 deg.

So this is a small frustum, being 7.5cm along the side wall, 3.52cm across the big end and a very tiny 0.88cm across the small end.

Using my spreadsheet, the small end cutoff frequencies, below which useful resonance is not possible are listed below:

TE11 19.96GHz
TM01 26.08 GHz
TE21 33.12 GHz
TE01 41.55 GHz
TM11 41.55 GHz
TE31 45.36 GHz
TM21 55.69 GHz
TE12 57.81 GHz

Yet the paper author claims he calculates frustum resonance of:

TM mode 4.12 GHz, 6.13 GHz, 7.83 GHz
TE mode 7.438 GHz, 9.359 GHz, 11.10GHz

All of which are well below the 0.88cm small end diameter cutoff frequency.

Roger gave me a simple rule of thumb when dealing with small end cutoff freq in TE01 mode. Cutoff freq = c / (diameter in mtrs * 0.82).

I suspect the author may not fully understand microwave physics and what happens to a EM wave travelling inside a tapered waveguide frustum of variable diameter, that increases the guide wavelength from that external nor how to calculate the cutoff frequency of the small end of his frustum design.

Point being if he can't correctly predict frustum resonance nor the small end cutoff freq, the rest of his model and calculations must be questioned.

http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html

BTW here is Greg Egan's web site:
http://gregegan.customer.netspace.net.au/index.html
« Last Edit: 10/29/2015 07:11 AM by TheTraveller »
It Is Time For The EmDrive To Come Out Of The Shadows

Offline TheTraveller

The most respected labs that have performed this experiment have yielded almost no thrust.

Who are these "Most Respected Labs"? Where is there data, frustum dimensions, excitation modes, VNA resonance freq scans. Force measurement rig designs? I know of no failed EMDrive tests. Such data needs to be analysed as building and testing an EMDrive is not like baking a simple cake recipe. Get one step wrong and there will be no thrust.

So PLEASE SHARE the null data. We might just be able to work out where they went wrong and prevent other builders from making the same mistake.
It Is Time For The EmDrive To Come Out Of The Shadows

Offline rfcavity

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Of course resonances can exist in a tapered cavity that have lower frequencies than the size of the smallest end. The energy would just exist within the largest part effectively shortening the cavity. Greg even shows this in a plot.

This is similar to how partially loaded cavities work, which is a common way to back out permitivitty of materials.

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