Author Topic: EM Drive Developments - related to space flight applications - Thread 5  (Read 965554 times)

Offline not_a_physicist

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In my opinion it will be very unstable.
I attached a propeller to it and made the rig spin a bit. A video is attached. It at least looks stable. It does wobble like you'd expect if you poke it right, though.

I'm sure a magnetic bearing or that graphite-on-metal bearing would be better, but actually building something roughly emdrive-like is beyond me either way -- just hoping to throw an idea out there for people who can do that sort of thing.

Offline rfmwguy

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. Last pic is screenshot of another can with Phase overlay.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88
« Last Edit: 10/25/2015 08:06 PM by rfmwguy »

Offline SeeShells

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. I'll take some data and give you the Q in a few minutes.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88
Glad to help!

You think the Q could be low because of???? Where are you inserting the maggie in the frustum? You have other points to check?

Nice Slaughtering.  :o ;D Don't you hate soldering to a heavy heat sink?


Offline rfmwguy

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. I'll take some data and give you the Q in a few minutes.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88
Glad to help!

You think the Q could be low because of???? Where are you inserting the maggie in the frustum? You have other points to check?

Nice Slaughtering.  :o ;D Don't you hate soldering to a heavy heat sink?

I have my trusty BMF soldering iron...no worries. Think lower Q is almost all attributed to mesh sides as opposed to solid copper. Now that I know these dimensions give a great resonance and thermal lift is going to be there anyway, Phase II testing will probably be done with a new solid copper frustum. Bucyrus, here I come.

Edit - lower Q might also relate to the 50 ohm mismatch to magnetron radome. I was pleased to see 1.8:1 vswr overall, but it is not as good as a monopole or loop tuned for 2.4 GHz.
« Last Edit: 10/25/2015 08:30 PM by rfmwguy »

Offline SeeShells

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. I'll take some data and give you the Q in a few minutes.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88
Glad to help!

You think the Q could be low because of???? Where are you inserting the maggie in the frustum? You have other points to check?

Nice Slaughtering.  :o ;D Don't you hate soldering to a heavy heat sink?

I have my trusty BMF soldering iron...no worries. Think lower Q is almost all attributed to mesh sides as opposed to solid copper. Now that I know these dimensions give a great resonance and thermal lift is going to be there anyway, Phase II testing will probably be done with a new solid copper frustum. Bucyrus, here I come.

Edit - lower Q might also relate to the 50 ohm mismatch to magnetron radome. I was pleased to see 1.8:1 vswr overall, but it is not as good as a monopole or loop tuned for 2.4 GHz.
I have a propane blowtorch I use but I guess somethings are left to the big girls.  ;D

I read somewhere on the net, gwad it was months ago, I'll see if I can find it again where someone replaced the radome with a antenna arrangement. I'll have to find it again.

If you're exciting a TM mode then much is in the walls If I remember correctly, but today the brain is fried. Need football.... lol

Offline SeeShells

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Offline tchernik

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. I'll take some data and give you the Q in a few minutes.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88
Glad to help!

You think the Q could be low because of???? Where are you inserting the maggie in the frustum? You have other points to check?

Nice Slaughtering.  :o ;D Don't you hate soldering to a heavy heat sink?

I have my trusty BMF soldering iron...no worries. Think lower Q is almost all attributed to mesh sides as opposed to solid copper. Now that I know these dimensions give a great resonance and thermal lift is going to be there anyway, Phase II testing will probably be done with a new solid copper frustum. Bucyrus, here I come.

Edit - lower Q might also relate to the 50 ohm mismatch to magnetron radome. I was pleased to see 1.8:1 vswr overall, but it is not as good as a monopole or loop tuned for 2.4 GHz.


Interesting. It seems Q factor was really low with the copper wire mesh, which could explain the low thrust.

It now seems evident copper mesh wasn't the best option after all.

But if you got evidence of anomalous thrust even in those conditions, I wonder what a certifiably high Q frustum would do with your same setup...

Best of luck!

 

 

Offline Bob Woods

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Just about ready to put all the parts together....
Pics and Centerfolds (clean centerfolds)
http://s1039.photobucket.com/user/shells2bells2002/media/CE%20Electromagnetic%20Reaction%20Thruster/EM%20thruster%20016_zpsdj5mg8vf.jpg.html?sort=3&o=0

That is one helluva job there Shell. I'm very impressed.

Congratulations.  :D

Offline SeeShells

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Offline TheTraveller

NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. Last pic is screenshot of another can with Phase overlay.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88

Nice work Dave. Good to see the SPR inspired spreadsheet's dimensional data got your frustum's resonance into the maggies output freq range.

Now replace the lossy sides with solid polished copper and see if that increases your loaded Q.

Please remember Rogers advise to run these scans as slow as you can so to give the frustum enough time to properly fill the cavity (at least 10x the expected cavity time constant dwell time at each freq step) or the reported loaded Q value may be lower and the VSWR higher than reality.

It might also be interesting to see the result if the antenna is mounted on the frustum side wall as Iulian did. You could try quite a few mounting sites and record any changes to resonance and VSWR.
It Is Time For The EmDrive To Come Out Of The Shadows

Offline rfmwguy

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. I'll take some data and give you the Q in a few minutes.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88
Glad to help!

You think the Q could be low because of???? Where are you inserting the maggie in the frustum? You have other points to check?

Nice Slaughtering.  :o ;D Don't you hate soldering to a heavy heat sink?

I have my trusty BMF soldering iron...no worries. Think lower Q is almost all attributed to mesh sides as opposed to solid copper. Now that I know these dimensions give a great resonance and thermal lift is going to be there anyway, Phase II testing will probably be done with a new solid copper frustum. Bucyrus, here I come.

Edit - lower Q might also relate to the 50 ohm mismatch to magnetron radome. I was pleased to see 1.8:1 vswr overall, but it is not as good as a monopole or loop tuned for 2.4 GHz.


Interesting. It seems Q factor was really low with the copper wire mesh, which could explain the low thrust.

It now seems evident copper mesh wasn't the best option after all.

But if you got evidence of anomalous thrust even in those conditions, I wonder what a certifiably high Q frustum would do with your same setup...

Best of luck!
Thanks. Yes, the mesh worked, but didn't hinder thermal lift like I thought. Certainly not worth lower Q. Already am planning on solid copper for phase II. That alone should gain some force increase.

Offline rfmwguy

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NSF-1701 Update - Thanks to Shell, I received the defective magnetron, took the connector off and soldered an SMA pigtail to it. Works great! Also attached very first VNA return loss scan. Note it centers right up where it is supposed to. Last pic is screenshot of another can with Phase overlay.

Center frequency = 2.432 GHz with 11.6dB return loss
Q per Yang method = 821
Q per Nasa method = 437

My Qr factor = 1.88

Nice work Dave. Good to see the SPR inspired spreadsheet's dimensional data got your frustum's resonance into the maggies output freq range.

Now replace the lossy sides with solid polished copper and see if that increases your loaded Q.

Please remember Rogers advise to run these scans as slow as you can so to give the frustum enough time to properly fill the cavity (at least 10x the expected cavity time constant dwell time at each freq step) or the reported loaded Q value may be lower and the VSWR higher than reality.

It might also be interesting to see the result if the antenna is mounted on the frustum side wall as Iulian did. You could try quite a few mounting sites and record any changes to resonance and VSWR.
That's right Phil, the spreadsheet was spot-on at resonance predictions. Congrats on creating that useful builder tool. Yes, solid copper for phase II is the plan.

Offline TheTraveller

That's right Phil, the spreadsheet was spot-on at resonance predictions. Congrats on creating that useful builder tool. Yes, solid copper for phase II is the plan.

Not my work alone. Roger laid a trail of bread crumbs for me to follow and helped in comparing the spreadsheet predictions as against the in house SPR EMDrive design tool predictions.

Your VNA resonance freq data adds more credibility yet again to the predictions the spreadsheet makes.

You, Shell and I are older engineers who like to know what we are building has a even or better chance of working as desired.
It Is Time For The EmDrive To Come Out Of The Shadows

Offline SeeShells

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Thoughts??? I'm considering on putting a top cap to deflect hot air 900 away from the frustum. The beryllium gasket seal between the ceramic top plate and tuning chamber will leak hot air.

Offline rfmwguy

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Thoughts??? I'm considering on putting a top cap to deflect hot air 900 away from the frustum. The beryllium gasket seal between the ceramic top plate and tuning chamber will leak hot air.
Forcing hot air horizontally will eventually find an edge and rise. But..if it could be cooled enough before edge was reached...hmmmm

Offline SeeShells

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Thoughts??? I'm considering on putting a top cap to deflect hot air 900 away from the frustum. The beryllium gasket seal between the ceramic top plate and tuning chamber will leak hot air.
Forcing hot air horizontally will eventually find an edge and rise. But..if it could be cooled enough before edge was reached...hmmmm
I know, you're a sharp guy.

Maybe it's simpler to just to throw a heater in it and profile the thermal component?
Or...
Added: I've thought of adding a reflective heat barrier at the top and fill the cavity with
Added: http://www.radiantguard.com/collections/reflective-insulation/products/reflective-insulation-double-bubble-white-rgwii48x125
I'll have enough of this left over to do a circle to set in the very top.
https://cdn.shopify.com/s/files/1/0054/6682/products/scrubber_in_pipe_cut.jpg?v=1399309566
I could cool it down easy enough
« Last Edit: 10/26/2015 02:30 AM by SeeShells »

Offline CW

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Perhaps it makes more sense to create a bad vacuum (e.g. one tenth of atmospheric pressure) with a simple and cheap pump in an enclosure with the test article in it? We just want to increase SNR considerably, right? I don't think that a hard vacuum is needed. We just want to get rid of most of the buoyancy for now. My 2 cents ;) .

Edit: Actually, it should easily be possible to create a pretty hard vacuum the cheap way:

1) 3D-print a metallic enclosure with cooling channels for liquid nitrogen in the walls, perhaps even just the bottom/floor of the enclosure.
2) Put an automated, complete test article in it (sorta like a space probe)
3) Shut the enclosure and fill it with pure CO2, so that all other gases are pushed out of the enclosure
4) Seal the enclosure and start pumping liquid nitrogen through the wall channels. The CO2 freezes out, until there's only solid dry ice left (maybe best only on bottom/floor of enclosure)
5) You got vacuum  8)

What do you guys think about this method?
« Last Edit: 10/26/2015 07:24 AM by CW »
Reality is weirder than fiction

Offline Mezzenile

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Thoughts??? I'm considering on putting a top cap to deflect hot air 900 away from the frustum. The beryllium gasket seal between the ceramic top plate and tuning chamber will leak hot air.
Forcing hot air horizontally will eventually find an edge and rise. But..if it could be cooled enough before edge was reached...hmmmm
This WEB page gives formula to make estimate of the air velocity in the center of a convective flow : http://www.engineeringtoolbox.com/convective-air-flow-d_1006.html

The study of the sensitivity of the formula to its parameters can help to chose a design which reduces the velocity of the convective flow.

Offline TheTraveller

Perhaps it makes more sense to create a bad vacuum (e.g. one tenth of atmospheric pressure) with a simple and cheap pump in an enclosure with the test article in it? We just want to increase SNR considerably, right? I don't think that a hard vacuum is needed. We just want to get rid of most of the buoyancy for now. My 2 cents ;) .

Edit: Actually, it should easily be possible to create a pretty hard vacuum the cheap way:

1) 3D-print a metallic enclosure with cooling channels for liquid nitrogen in the walls, perhaps even just the bottom/floor of the enclosure.
2) Put an automated, complete test article in it (sorta like a space probe)
3) Shut the enclosure and fill it with pure CO2, so that all other gases are pushed out of the enclosure
4) Seal the enclosure and start pumping liquid nitrogen through the wall channels. The CO2 freezes out, until there's only solid dry ice left (maybe best only on bottom/floor of enclosure)
5) You got vacuum  8)

What do you guys think about this method?

Or you can increase the EMDrive generated Force so it is very much larger than the buoyancy Force as Roger did with his 2002 Experimental EMDrive.

The buoyancy Force level and effects are very clear in his measurement data. The Force ramps are due to mechanical tuning at each end of the Frustum. This was the last frustum with flat end plates and using a dielectric.
It Is Time For The EmDrive To Come Out Of The Shadows

Offline CW

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A number of our DIYers do have an own setup or are in the process of building it. I proposed this ad-hoc method to have a way to create a very good testing vacuum without any expensive vacuum pumps. This method does not really have anything to do with Mr. Shawyer's or anyone else's device. I'm just going by the principle that what's not there cannot influence the measurements. Why compensate for something, if there is a way to get rid of that something altogether? What plagues EM-drive research is really having to account for a number of annoying effects that hide the mostly miniscule effects. And I still find it worrysome that almost no experiments were performed under vacuum conditions. BTW, if Mr. Shawyer's device is as powerful as you state, I think we would all appreciate a public demonstration with multi-Newton performance anytime soon. As far as I can see, it's just talk talk talk about how wonderful Mr. Shawyer's device is. It's PowerPoint level credibility. That's why I esteem our DIYers so highly on this forum - they actually show their stuff. Quite the opposite of PowerPoint level 'discussions'.

Best regards
Reality is weirder than fiction

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