Author Topic: EM Drive Developments - related to space flight applications - Thread 5  (Read 713421 times)

Offline rfmwguy

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Please dont give up, i am looking forward to your (and SheShell's) next results!
I hope sometimes we can explain this effect with the math(More conclusive than the present tries.).
That's possibly the way to the stars. :)
Nope, not quitting right now. I figured whatever emdrive effect I measured is about 2.4x of my noise floor and I did my best to account for all system noise. Altho I have a high confidence factor, I am also a realist and realize 177 micronewtons will not get us to the stars anytime soon. So, my Phase II design (on same test bed) will shoot for 17.5 millinewtons. When this happens, its back to the books to work on theory. Don't think my humble home lab could get higher performance.

Offline Prunesquallor

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Think thats why I temporarily gave up on the theory end of things as nothing I read or already knew made any sense when trying to apply it to emdrive. So to avoid brain tilt, thought I would build one and see. Now thats done and I might get more dramatic results in Phase II (if that happens) I might stick my toe back into the theory world. I'll then try again to look for anything that references kinetic energy and electromagnetic radiation. Seem to recall I drew a big fat zero as no one, including me, would have ever thought to look for it.

One avenue I wanted to explore someday is geosyncronous sats. The ones that transmit downlinks at fairly high power. What is their station-keepin needs, etc.

Not getting exactly why you are interested in geostationary, but to answer your question (kinda) the station keeping requirements are relatively low, both from a thrust level and total impulse, but quite strict - to keep your sat from intruding on anyone else's slot (Russians don't seem to feel this applies to them). Modern geosats use electric propulsion thrusters, so one might think that EMDrive thrusters would be applicable, but because the lifetime impulse is so low, the sats don't use a lot of propellant, so a "propellant less" thruster might not be that advantageous.
« Last Edit: 10/30/2015 08:01 AM by Prunesquallor »
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Offline rfmwguy

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Think thats why I temporarily gave up on the theory end of things as nothing I read or already knew made any sense when trying to apply it to emdrive. So to avoid brain tilt, thought I would build one and see. Now thats done and I might get more dramatic results in Phase II (if that happens) I might stick my toe back into the theory world. I'll then try again to look for anything that references kinetic energy and electromagnetic radiation. Seem to recall I drew a big fat zero as no one, including me, would have ever thought to look for it.

One avenue I wanted to explore someday is geosyncronous sats. The ones that transmit downlinks at fairly high power. What is their station-keepin needs, etc.

Not getting exactly why you are interested in geostationary, but to answer your question (kinda) the station keeping requirements are relatively low, both from a thrust level and total impulse, but quite strict - to keep your sat from intruding on anyone else's slot (Russians don't seem to feel this applies to them). Modern geosats use electric propulsion thrusters, so one might think that EMDrive thrusters would be applicable, but because the lifetime impulse is so low, the sats don't use a lot of propellant, so a "propellant less" thruster might not be that advantageous.
Interesting...has anyone ever studied the "drift" or stationkeeping requirements over months or years? For example, for steady state believers it would seem no stationkeeping would be required at all. If there is, what is the cause and in which vector does the satellite want to "drift"?

Offline meberbs

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Interesting...has anyone ever studied the "drift" or stationkeeping requirements over months or years? For example, for steady state believers it would seem no stationkeeping would be required at all. If there is, what is the cause and in which vector does the satellite want to "drift"?

What do you mean by "steady state believers"?

Geostationary satellites have to deal with pressure from the solar wind, drift due to inexact placement (not perfect altitude/not perfectly circular, etc.), and effects from lunar gravity. They don't have to deal with the residual atmospheric drag and earth oblateness effects that LEO satellites do, but the effect from the moon should be stronger. I haven't done any work to characterize the needs, but I am fairly confident things like direction would depend on the initial conditions and strength of the solar cycle too sensitively to predict accurately.

Usually satellites are designed with full control in all rotational and linear directions, generally in a configuration that allows some redundancy. That way there is no need to know the exact requirements in advance.

Edit: according to Wikipedia, 40-50 m/s per year is required to account for gravitational perturbations to the orbit (solar and lunar gravity effects) Presumably, depending on the total drift allowed, there could be ways to optimize propellant use and an individual satellite may need more or less.
« Last Edit: 10/30/2015 12:52 PM by meberbs »

Online 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.

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 )

It's a shortcut to a facebook photo gallery, so if you're not on FB it might not work.  Here's my page for LCROSS at NASA Ames: http://lcross.arc.nasa.gov/bios/NG_stagmer.htm
I'm also @VAXHeadroom on Twitter.
I have this project in mind for our current spaceflight electronics designs.  We can output KW for a few minutes per orbit in a Cubesat form factor.  More details once we can publicly announce our avionics.
A 6u Cubesat is 100x225x300mm.  A 12u is 200x225x300mm. the 300 extends to about 365 if you go with the Planetary Systems deployer.  They also have a 27u deployer, but we haven't really investigated that yet.  This means you'd be limited to a 200mm(~8") diameter without an expandable frustrum.  I love the 'collapsible camping cup' idea :)
Thrust can be measured in the Rf Doppler shift - I know from LCROSS that changes in velocity as small as mm/sec can be measured - we measured the shift when the Centaur upper stage was heated up in flight and outgassed water it had soaked up while sitting on the pad in FL.
These size satellites can have down to arcsecond pointing capability, so control is not a problem.  Yes, we're talking about a $1M mission, but I have potential research funding sources if this ever gets out of the 'noise' :)
Emory Stagmer
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Offline rfmwguy

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This is why most people are afraid to build EMDrives:
https://www.facebook.com/stagefreaks/videos/863975723671117/

Offline rfmwguy

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Interesting...has anyone ever studied the "drift" or stationkeeping requirements over months or years? For example, for steady state believers it would seem no stationkeeping would be required at all. If there is, what is the cause and in which vector does the satellite want to "drift"?

What do you mean by "steady state believers"?

Geostationary satellites have to deal with pressure from the solar wind, drift due to inexact placement (not perfect altitude/not perfectly circular, etc.), and effects from lunar gravity. They don't have to deal with the residual atmospheric drag and earth oblateness effects that LEO satellites do, but the effect from the moon should be stronger. I haven't done any work to characterize the needs, but I am fairly confident things like direction would depend on the initial conditions and strength of the solar cycle too sensitively to predict accurately.

Usually satellites are designed with full control in all rotational and linear directions, generally in a configuration that allows some redundancy. That way there is no need to know the exact requirements in advance.

Edit: according to Wikipedia, 40-50 m/s per year is required to account for gravitational perturbations to the orbit (solar and lunar gravity effects) Presumably, depending on the total drift allowed, there could be ways to optimize propellant use and an individual satellite may need more or less.
Immutable vacuum.

So, all the analysis was done with assumptions of gravity and solar wind? What about effects from the Pioneer Anomaly? Sounds to me like station-keeping is a matter of correction, not cause. Am I wrong?

Offline Mezzenile

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Immutable vacuum.

So, all the analysis was done with assumptions of gravity and solar wind? What about effects from the Pioneer Anomaly? Sounds to me like station-keeping is a matter of correction, not cause. Am I wrong?
I  think that the Pionner anomaly is an effect several order of magnitude lower than the perturbations experienced by a geostationary satellite.
One important perturbation is due to the oblatness of the earth which induces an inclination versus time of the equatorial orbit of the satellite.

Today when a satellite reachs its end of life (equipment failure or shortage of power delivered by solar arrays or more probably : no more propelant available to maintain the orbital position), it has to use its last propelant reserve to reach a so called "cemetery orbit" to avoid any risk of disastrous collision with an other geostationary satellites.
« Last Edit: 10/30/2015 07:19 PM by Mezzenile »

Offline Prunesquallor

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Interesting...has anyone ever studied the "drift" or stationkeeping requirements over months or years? For example, for steady state believers it would seem no stationkeeping would be required at all. If there is, what is the cause and in which vector does the satellite want to "drift"?

What do you mean by "steady state believers"?

Geostationary satellites have to deal with pressure from the solar wind, drift due to inexact placement (not perfect altitude/not perfectly circular, etc.), and effects from lunar gravity. They don't have to deal with the residual atmospheric drag and earth oblateness effects that LEO satellites do, but the effect from the moon should be stronger. I haven't done any work to characterize the needs, but I am fairly confident things like direction would depend on the initial conditions and strength of the solar cycle too sensitively to predict accurately.

Usually satellites are designed with full control in all rotational and linear directions, generally in a configuration that allows some redundancy. That way there is no need to know the exact requirements in advance.

Edit: according to Wikipedia, 40-50 m/s per year is required to account for gravitational perturbations to the orbit (solar and lunar gravity effects) Presumably, depending on the total drift allowed, there could be ways to optimize propellant use and an individual satellite may need more or less.
Immutable vacuum.

So, all the analysis was done with assumptions of gravity and solar wind? What about effects from the Pioneer Anomaly? Sounds to me like station-keeping is a matter of correction, not cause. Am I wrong?

All the major perturbing effects can be modeled quite accurately, so the spacecraft designers have a pretty good idea how much propellant they will need over the satellite's lifetime. These are all forces that perturb the satellite from the desired orbit position, so you can't solve it just by accurate initial conditions.

Generally, ground tracking will be keeping track of the satellite's position and velocity, so the mission planners will be able to predict when they will exceed specified limits. Then they will command the appropriate correction maneuver.
Retired, yet... not

Offline X_RaY

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Please dont give up, i am looking forward to your (and SheShell's) next results!
I hope sometimes we can explain this effect with the math(More conclusive than the present tries.).
That's possibly the way to the stars. :)
Nope, not quitting right now. I figured whatever emdrive effect I measured is about 2.4x of my noise floor and I did my best to account for all system noise. Altho I have a high confidence factor, I am also a realist and realize 177 micronewtons will not get us to the stars anytime soon. So, my Phase II design (on same test bed) will shoot for 17.5 millinewtons. When this happens, its back to the books to work on theory. Don't think my humble home lab could get higher performance.
Glad to read that. I am also realistic and, you know, my "way to the stars" -statement was a little metaphorically ::) but it may be (or even not) one of the first steps to realize this dream. However, all of us can learn something more about physics this way in this forum. :) So its a win-win situation even if it doesn't work, or works only with tiny effectivity.
« Last Edit: 10/30/2015 10:34 PM by X_RaY »

Offline TheTraveller

Hey Dave,

Ran your numbers again to find what mode NSF-1701 resonated in. Based on the published dimensions as below

Big end 0.2791m
Small end 0.1588m
Length 0.2591m

I got the closest match for 2.45GHz in TE114 as attached (frustum length was a 1.3mm too short for an exact match at 2.45GHz). Then used Excel goal seek to fine tune the freq and got 2.46GHz which is close enough to what your VNA reported. Of course length variations will alter the resonance a bit.

Data attached.

I'm fairly happy we now have a tool that can both predict frustum resonance and the resonant mode excited.
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Offline TheTraveller

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 )

It's a shortcut to a facebook photo gallery, so if you're not on FB it might not work.  Here's my page for LCROSS at NASA Ames: http://lcross.arc.nasa.gov/bios/NG_stagmer.htm
I'm also @VAXHeadroom on Twitter.
I have this project in mind for our current spaceflight electronics designs.  We can output KW for a few minutes per orbit in a Cubesat form factor.  More details once we can publicly announce our avionics.
A 6u Cubesat is 100x225x300mm.  A 12u is 200x225x300mm. the 300 extends to about 365 if you go with the Planetary Systems deployer.  They also have a 27u deployer, but we haven't really investigated that yet.  This means you'd be limited to a 200mm(~8") diameter without an expandable frustrum.  I love the 'collapsible camping cup' idea :)
Thrust can be measured in the Rf Doppler shift - I know from LCROSS that changes in velocity as small as mm/sec can be measured - we measured the shift when the Centaur upper stage was heated up in flight and outgassed water it had soaked up while sitting on the pad in FL.
These size satellites can have down to arcsecond pointing capability, so control is not a problem.  Yes, we're talking about a $1M mission, but I have potential research funding sources if this ever gets out of the 'noise' :)

How much Force do you need a cubesat EMDrive to deliver? Knowing the Force desired then the needed Rf watts can be calculated. Your job to deliver those Rf watts and ensure there is enough primary power available. Can design to many dimensions knowing the Rf drive freq, which will need to real time track lowest VSWR or lowest reflected power to achieve and hold resonance. I assume it needs to fit inside 1 cube being 100mmx100mmx100mm?
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Offline TheTraveller

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.

If the EM wave can't reach the end plate, as the diameter is well below cutoff, how will the EM wave be able of efficiently propogate to bounce off an end plate it can't reach?

Or do you ignore Roger's advise to ALWAYS operate the small end ABOVE cutoff?

The small end of the cavity is 8.8mm in dia, the big end is 35.2mm in dia and the end plate separation is 75mm.  You really believe that cavity will resonate at 4.1GHz despite the small end cutoff being 40GHz and the big end cutoff being 10GHz.

Even disallowing that both ends are claimed to be happily operating WELL below cutoff, to achieve resonance some whole number of 1/2 waves at the effective overall guide wavelength need to fit between the end plates.

There is no way what can happen.

His resonance model is rubbish.

Waves don't bounce in a cavity. It's a resonance that has math different from physical bouncing. Bouncing is a way to explain to people without math, but the analogy does not hold 100% and is not perfect.

By the way, the method you use to calculate cut off uses cut offs derived from cylinder cavities. In textbooks, these cutoff equations are derived exactly the same way as Greg derives for the tapered cavity. So if he is wrong, by rule, you are also wrong.

However, checking his work, he is right. I trained in EM. Rodal also says he is right. Please, show what part of his work is wrong, instead of writing paragraphs.

No they don't bounce. They get absorbed by the end plate and reemitted.

If you are EM trained then please explain to me how a 8.8mm diameter waveguide can propagate a 4.12GHz EM wave? In fact neither can the big end at 3.52mm diameter propagate that EM wave. So both ends of the proposed Egan cavity are well below cutoff and can NOT propagate a 4.12GHz EM wave, yet he claims resonance.

You may wish to believe the EMDrive is a work of fiction, so be it, but this paper will not support your belief.

BTW please show me where Egan is EM trained or experienced? All I can find is he holds a BS in Maths and is a sifi writer and programmer. What amazes me is despite Egan having apparently no microwave training nor experience, so many EMDrive deniers jumped on this paper and totally ignored his apparent lack of credibility in the black arts of microwave waveguide physics.
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Herman Melville, Moby Dick

Offline TheTraveller


According to your logic, no resonances could exist at all in a cone shaped cavity. That is an incorrect claim, easily testable by experiment. ...

I think you missed the key work efficiently in TT's post. Yes of course you can get any shape to resonate, but to resonate with high quality and low losses we want to minimize the evanescent decay. When wave bounces off an opening because its wavelength is too large to fit, some energy will still propagate into the opening and decay exponentially.
I believe what he and Shawyer are getting at is we should have each side of the resonator be above the cutoff, not that we have to.

Correct.

The only way to achieve a high Q is to ensure the small end operates above cutoff. If your end plates are spherical this also encourages the EM waves to form matching spherical wave fronts, which reduces significantly bounce phase distortion and also reduces side wall radiation pressure to almost nothing.

Getting a EMDrive to work well is like following a somewhat complex baking recipe. Make a major mistake or omission and there is not Force generated, make minor mistakes and you may get some small Force generated or maybe not. Do everything right and the Force will be significant.

I firmly believe that a specific Force of 1N/kW is achieve in DIY EMDrive builds as long as Roger's bread crumb trail is followed.
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Offline TheTraveller

I'm getting excited as I can see, in regard to my health issues, the light at the end of the tunnel.

The delay has probably been overall, a good thing, as I have redesigned my EMDrive, rotary test table and data monitoring / recording system quite a few times. I also understand how and why the EMDrive works a whole lot better than before the prostate cancer issue took me off line as a DIY builder.

My goal now is to be able to publish my results before Eagleworks publishes theirs.

Just to be very clear about my intentions here, which I have stated before, I will do the independent tester program and then start commercial sales of fully operation total EMDrive systems. Each system will be furnished will full test data from many test runs on the rotary test rig.

I believe there are a very significant number of universities, gov labs, commercial companies and individuals which would welcome being able to test and evaluate a known working high fidelity EMDrive in their lab.

Anyone wishing my assistance to design and build a custom EMDrive will be able to engage that process.
« Last Edit: 10/30/2015 11:48 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Online VAXHeadroom

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...
How much Force do you need a cubesat EMDrive to deliver? Knowing the Force desired then the needed Rf watts can be calculated. Your job to deliver those Rf watts and ensure there is enough primary power available. Can design to many dimensions knowing the Rf drive freq, which will need to real time track lowest VSWR or lowest reflected power to achieve and hold resonance. I assume it needs to fit inside 1 cube being 100mmx100mmx100mm?
To fit in a 12u cubesat, large dia can be up to 20cm with length up to 36cm.  To accelerate a 10Kg cubesat at 10mm/s would take...what... 100mN?  I'm guessing on the math here - too late at night - I'm probably off by some powers of 10...  We can give you a KW for several minutes once per orbit, only limit is how hot the batteries get and how far we discharge them.  More than a 20% depth of discharge will limit their life, but this is probably a limited life test anyway (not a multi-year mission) so we can maybe run them harder and/or pack in more batteries to give us more instantaneous power...
« Last Edit: 10/31/2015 12:39 AM by VAXHeadroom »
Emory Stagmer
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Offline TheTraveller

...
How much Force do you need a cubesat EMDrive to deliver? Knowing the Force desired then the needed Rf watts can be calculated. Your job to deliver those Rf watts and ensure there is enough primary power available. Can design to many dimensions knowing the Rf drive freq, which will need to real time track lowest VSWR or lowest reflected power to achieve and hold resonance. I assume it needs to fit inside 1 cube being 100mmx100mmx100mm?
To fit in a 12u cubesat, large dia can be up to 20cm with length up to 36cm.  To accelerate a 10Kg cubesat at 10mm/s would take...what... 100mN?  I'm guessing on the math here - too late at night - I'm probably off by some powers of 10...  We can give you a KW for several minutes once per orbit, only limit is how hot the batteries get and how far we discharge them.  More than a 20% depth of discharge will limit their life, but this is probably a limited life test anyway (not a multi-year mission) so we can maybe run them harder and/or pack in more batteries to give us more instantaneous power...

Quick analysis suggest the 20cm big end limitation reduces the Df ( F = (2 Df unloadedQ P) / c ) quite a bit. But working on that limitation I get a highly optimised small end of 14.95cm and length of 15.07cm (mode TE011 @ 2.45GHz), with spherical end plates, using a 20% solid state amp conversion efficiency to Rf and 1kW power input could deliver, at a conservative unloaded Q of 50,000 (25,000 as measured loaded Q) around 40mN, generating say 4mm/sec acceleration with a 10kg mass.

If a higher unloaded Q of say 100,000, 50,000 as measured, can be achieved, the acceleration climbs to 8mm/sec.

If we can find or afford a higher efficiency Rf amp, the output Rf power would climb as so would the Force generated.

So say 40mN doable and maybe 100mN as the top end.  Note the frustum length is 15cm, so the frustum mass is reduced from your 35cm allowance. This may help to drop the 10kg mass and so increase the acceleration.

Biggest issue I see is sourcing a low mass and highly efficient min 200W solid state Rf amp AND dealing with the 800Ws of waste heat. Maybe better to go for a lower output power Rf amp that can run 24/7, instead of doing short bursts of acceleration.
« Last Edit: 10/31/2015 01:17 AM by TheTraveller »
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Offline SeeShells

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This is why most people are afraid to build EMDrives:
https://www.facebook.com/stagefreaks/videos/863975723671117/

Oh. My. God. Now I'm in tears... good grief rfmwguy I've not laughed that hard in a very long time.

Shell

Offline TheTraveller

This is why most people are afraid to build EMDrives:
https://www.facebook.com/stagefreaks/videos/863975723671117/

Oh. My. God. Now I'm in tears... good grief rfmwguy I've not laughed that hard in a very long time.

Shell

Ditto. Roger that.

That video is a classic and in reality every engineer has done similar stupid stuff, learning very quickly what burnt flesh smells like and what electric shocks feel like. Part of the engineers "Rite of passage".
« Last Edit: 10/31/2015 01:30 AM by TheTraveller »
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Offline ThinkerX

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Quote
Biggest issue I see is sourcing a low mass and highly efficient min 200W solid state Rf amp AND dealing with the 800Ws of waste heat. Maybe better to go for a lower output power Rf amp that can run 24/7, instead of doing short bursts of acceleration.

Suggestion from the peanut gallery:

use the waste heat to generate electricity.  (thermocouples?)   Won't get anywhere near unity, but might offset the power bill some.

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