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#2660
by
Monomorphic
on 22 May, 2016 13:26
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Monomorph, the advantage of oil damping is that, that is all it does. It is a tried and tested method. The added complexity of remote control devices should maybe not be added unless necessary. Plexiglass draught exclusion and faraday cage sound to me like essentials.
I think I have decided to integrate the laser onto the tortional pendulum, so that will need to be controlled remotely anyway. Then it is just a matter of VPNing into the computer in the workshop to control the webcams. Powering the magnetron is already accomplished via a remote switch, so it will be simple to run that switch into the adjacent room.
So for the cost of a few remote control switches, I could eliminate the need for a draught exclusion enclosure - by conducting the experiment from another room. I'm not sure a Faraday cage is necessary.
http://nl.aliexpress.com/store/product/Wireless-Remote-Control-Switch-433mhz-3-7v-4-5v-5v-6v-9v-12v-Micro-Receiver-Switch/318345_32222742949.html?storeId=318345
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#2661
by
SeeShells
on 22 May, 2016 15:46
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Monomorph, the advantage of oil damping is that, that is all it does. It is a tried and tested method. The added complexity of remote control devices should maybe not be added unless necessary. Plexiglass draught exclusion and faraday cage sound to me like essentials.
I think I have decided to integrate the laser onto the tortional pendulum, so that will need to be controlled remotely anyway. Then it is just a matter of VPNing into the computer in the workshop to control the webcams. Powering the magnetron is already accomplished via a remote switch, so it will be simple to run that switch into the adjacent room.
So for the cost of a few remote control switches, I could eliminate the need for a draught exclusion enclosure - by conducting the experiment from another room. I'm not sure a Faraday cage is necessary.
http://nl.aliexpress.com/store/product/Wireless-Remote-Control-Switch-433mhz-3-7v-4-5v-5v-6v-9v-12v-Micro-Receiver-Switch/318345_32222742949.html?storeId=318345
Sounds like a great idea to do it remotely.
Believe it or not, a gnat weighs ~2 milligrams and were trying to measure his wings. You bet I'm going to enclose my test bed. If you glued a gnat onto the side of your frustum you could measure the thrust he generated when he tried to fly with this setup.
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#2662
by
FattyLumpkin
on 22 May, 2016 19:23
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X_Ray, are you running FEKO LITE or do you have a more advanced version. I want to download FL, but am not sure if it would be adequate for appropriate sims. I'd still like to go with a x2 build, but wouldn't move on it without excellent sims. FL, Kevin
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#2663
by
Monomorphic
on 22 May, 2016 19:24
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I had to fabricate a monopole antenna to use with the miniVNA Tiny. This mounts in the same place as the magnetron, so it is easy to switch them back and forth. Hope to have some return loss sweeps by this evening.
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#2664
by
X_RaY
on 22 May, 2016 19:49
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X_Ray, are you running FEKO LITE or do you have a more advanced version. I want to download FL, but am not sure if it would be adequate for appropriate sims. I'd still like to go with a x2 build, but wouldn't move on it without excellent sims. FL, Kevin
You will find the answer there
http://forum.nasaspaceflight.com/index.php?topic=39214.msg1536573#msg1536573To stay clear these are Eigen-resonance calculations. If you like to model the frustum with antenna and antenna feed a full version of any calculation program is strongly recommended!
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#2665
by
Monomorphic
on 22 May, 2016 20:54
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More images showing how the laser was integrated into the torsional pendulum. There will be a 3.7v remote-control switch to turn it on and off.
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#2666
by
frobnicat
on 22 May, 2016 22:00
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Monomorph, the advantage of oil damping is that, that is all it does. It is a tried and tested method. The added complexity of remote control devices should maybe not be added unless necessary. Plexiglass draught exclusion and faraday cage sound to me like essentials.
I think I have decided to integrate the laser onto the tortional pendulum, so that will need to be controlled remotely anyway. Then it is just a matter of VPNing into the computer in the workshop to control the webcams. Powering the magnetron is already accomplished via a remote switch, so it will be simple to run that switch into the adjacent room.
So for the cost of a few remote control switches, I could eliminate the need for a draught exclusion enclosure - by conducting the experiment from another room. I'm not sure a Faraday cage is necessary.
http://nl.aliexpress.com/store/product/Wireless-Remote-Control-Switch-433mhz-3-7v-4-5v-5v-6v-9v-12v-Micro-Receiver-Switch/318345_32222742949.html?storeId=318345
Sounds like a great idea to do it remotely.
Believe it or not, a gnat weighs ~2 milligrams and were trying to measure his wings. You bet I'm going to enclose my test bed. If you glued a gnat onto the side of your frustum you could measure the thrust he generated when he tried to fly with this setup.
@Shell, just to be clear, are you aiming at measuring
down to µN levels with your setup ? One kilogram force is (roughly) 10 newtons, one gram force is (roughly) 10 millinewtons,
one milligram force is (roughly) 10 micronewtons. 1 mN (millinewton) ≈ 0.1 g (a tenth of a gram) amounts to the weight of a 3.5cm by side cut out square of standard copier paper, roughly a letter stamp. A 2mg gnat is worth 20µN, I don't remember many EMdrive experiments navigating the realms of sub 20µN measurements except EagleWorks torsion pendulum.
@Monomorphic, a viscous friction damping system correctly tuned, such that the natural oscillations around the axis of interest are (roughly) being critically damped, will not decrease sensitivity as displacement for a given force will be the same when equilibrium is reached, and you'll avoid swinging beyond and back around the equilibrium, and the time to reach such equilibrium will not be significantly longer than the time needed for an un-damped system to run to same point... and overshoot, and ring around forever. A good viscous damping will not make the measurement more "sloppy" nor less sensitive. And it's not that expensive a piece of equipment.
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#2667
by
keithpickering
on 22 May, 2016 23:16
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7) Running an experiment with a power cord is therefore similar to running an experiment with a normal rocket using propellant coming from a stationary source. Such a test may be OK once one knows that rockets work, and one just wants to test their thrust, but it is unsatisfactory for a propellant-less device that is very much under question whether it can work in Space to self-accelerate.
It is entirely possible to test a rocket engine using propellant from a stationary source. In fact, it's done all the time. Usually that's done with a completely fixed engine. But it's possible to imagine a rocket engine on a rotary test stand with center-fed liquid fuel, for example. I fail to see how such a setup would necessarily give invalid test results.
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#2668
by
SeeShells
on 23 May, 2016 00:44
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Monomorph, the advantage of oil damping is that, that is all it does. It is a tried and tested method. The added complexity of remote control devices should maybe not be added unless necessary. Plexiglass draught exclusion and faraday cage sound to me like essentials.
I think I have decided to integrate the laser onto the tortional pendulum, so that will need to be controlled remotely anyway. Then it is just a matter of VPNing into the computer in the workshop to control the webcams. Powering the magnetron is already accomplished via a remote switch, so it will be simple to run that switch into the adjacent room.
So for the cost of a few remote control switches, I could eliminate the need for a draught exclusion enclosure - by conducting the experiment from another room. I'm not sure a Faraday cage is necessary.
http://nl.aliexpress.com/store/product/Wireless-Remote-Control-Switch-433mhz-3-7v-4-5v-5v-6v-9v-12v-Micro-Receiver-Switch/318345_32222742949.html?storeId=318345
Sounds like a great idea to do it remotely.
Believe it or not, a gnat weighs ~2 milligrams and were trying to measure his wings. You bet I'm going to enclose my test bed. If you glued a gnat onto the side of your frustum you could measure the thrust he generated when he tried to fly with this setup.
@Shell, just to be clear, are you aiming at measuring down to µN levels with your setup ? One kilogram force is (roughly) 10 newtons, one gram force is (roughly) 10 millinewtons, one milligram force is (roughly) 10 micronewtons. 1 mN (millinewton) ≈ 0.1 g (a tenth of a gram) amounts to the weight of a 3.5cm by side cut out square of standard copier paper, roughly a letter stamp. A 2mg gnat is worth 20µN, I don't remember many EMdrive experiments navigating the realms of sub 20µN measurements except EagleWorks torsion pendulum.
@Monomorphic, a viscous friction damping system correctly tuned, such that the natural oscillations around the axis of interest are (roughly) being critically damped, will not decrease sensitivity as displacement for a given force will be the same when equilibrium is reached, and you'll avoid swinging beyond and back around the equilibrium, and the time to reach such equilibrium will not be significantly longer than the time needed for an un-damped system to run to same point... and overshoot, and ring around forever. A good viscous damping will not make the measurement more "sloppy" nor less sensitive. And it's not that expensive a piece of equipment.
@frobnicat Even though a gnat weighs in at 2mg it takes more than 20uN of lift for it to fly. A torsional pendulum with fine enough wire can measure smaller than 20uN, even a DYIers (depending on the thickness, stiffness and length of the wire).
By just using a laser you can achieve better than 20uN resolution. It just takes time. F=M*A
In my case I will test using a set of digital scales and a laser to compare results.
I agree with you on the oil dampener not impacting the measurement for monomorphic.
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#2669
by
keithpickering
on 23 May, 2016 01:20
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As my earlier post illustrated, hanging an UN-POWERED magnetron from a torsion balance wire can yield about a 30 degree rotation, just from alignment with the Earth's magnetic field with the magnetron magnets.
That could be negated by surrounding the test setup with mu-metal. I'd be interested in knowing if solid foil would be required, or if a cage would work.
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#2670
by
FattyLumpkin
on 23 May, 2016 02:45
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Herr X_Ray, I'd like to be able to model (sim) both open and closed resonant cavities, for the closed, yes the frustum definitely, but also Cannae or Cannae equivalent geometries. As to RF I'm not entirely certain what would be needed, I suspect Maggie mono and di-pole + (?) others. As aforementioned, I have long suspected the Cannae geometry of being an asymmetric LINAC type cavity (see attached), and while LINACs are closed, I'd like to perform sims with an opening in a certain location with the cavity of a certain design.
Thanks for you input , FL
PS: Monomorphic, if you're not too swamped please chime in. K
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#2671
by
Rodal
on 23 May, 2016 07:24
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7) Running an experiment with a power cord is therefore similar to running an experiment with a normal rocket using propellant coming from a stationary source. Such a test may be OK once one knows that rockets work, and one just wants to test their thrust, but it is unsatisfactory for a propellant-less device that is very much under question whether it can work in Space to self-accelerate.
It is entirely possible to test a rocket engine using propellant from a stationary source. In fact, it's done all the time. Usually that's done with a completely fixed engine.
I have personally known that for several decades, as I have performed many such experiments with a hybrid rocket engine tested on the ground.
The point that was made, was not at all whether one is able to test a chemical rocket that way (as testing chemical rockets that way is a well known fact), but instead it was that:
"Such a test may be OK once one knows that rockets work, and one just wants to test their thrust, but it is unsatisfactory for a propellant-less device that is very much under question whether it can work in Space to self-accelerate"
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#2672
by
mk65
on 23 May, 2016 08:41
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Monomorph, the advantage of oil damping is that, that is all it does. It is a tried and tested method. The added complexity of remote control devices should maybe not be added unless necessary. Plexiglass draught exclusion and faraday cage sound to me like essentials.
I think I have decided to integrate the laser onto the tortional pendulum, so that will need to be controlled remotely anyway. Then it is just a matter of VPNing into the computer in the workshop to control the webcams. Powering the magnetron is already accomplished via a remote switch, so it will be simple to run that switch into the adjacent room.
So for the cost of a few remote control switches, I could eliminate the need for a draught exclusion enclosure - by conducting the experiment from another room. I'm not sure a Faraday cage is necessary.
http://nl.aliexpress.com/store/product/Wireless-Remote-Control-Switch-433mhz-3-7v-4-5v-5v-6v-9v-12v-Micro-Receiver-Switch/318345_32222742949.html?storeId=318345
Hello (please ignore if already thought about), just as a reminder to prevent additional experimental errors: As these items are only capable of switching ~1 A (which will hardly be sufficient), please just remember that when using electromechanical relays in addition, the switching motion of the relay contact, of course depending on its orientation and placement on the test rig also represents a potential shift of center of mass and accelerative impulse! So maybe one should better decide to use high power solid state switching devices.
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#2673
by
Monomorphic
on 23 May, 2016 10:47
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Hello (please ignore if already thought about), just as a reminder to prevent additional experimental errors: As these items are only capable of switching ~1 A (which will hardly be sufficient), please just remember that when using electromechanical relays in addition, the switching motion of the relay contact, of course depending on its orientation and placement on the test rig also represents a potential shift of center of mass and accelerative impulse! So maybe one should better decide to use high power solid state switching devices.
These switches would only power the laser and other small battery powered components. Powering the magnetron using batteries and a remote control will require something a lot beefier.
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#2674
by
Monomorphic
on 23 May, 2016 13:09
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Herr X_Ray, I'd like to be able to model (sim) both open and closed resonant cavities, for the closed, yes the frustum definitely, but also Cannae or Cannae equivalent geometries. As to RF I'm not entirely certain what would be needed, I suspect Maggie mono and di-pole + (?) others. As aforementioned, I have long suspected the Cannae geometry of being an asymmetric LINAC type cavity (see attached), and while LINACs are closed, I'd like to perform sims with an opening in a certain location with the cavity of a certain design.
Thanks for you input , FL
PS: Monomorphic, if you're not too swamped please chime in. K
If you plan on doing sims of anything more complicated than a simple frustum, then you may need to look at the full version of FEKO. FEKO lite limits the number of triangles per model to under a few hundred I believe. The sim I did of the Cannae drive was over 500 triangles.
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#2675
by
ByStander
on 23 May, 2016 15:20
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Monomorphic:
Have you considered simulating a stellarator shape?
It looks to me like some of the fields depicted in the frustums are spiraling. If the (possible) thrust is a result of interaction with the sides of the frustum, and if the field is sprialing, then sides having some variation of stellarator shape might be worth investigating.
Just a question from the peanut gallery. Please ignore and move on if it's too stupid.
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#2676
by
SeeShells
on 23 May, 2016 15:53
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NSF-1701A Update - About ready to test - FYI
Final cosmetic touches will be added to the frustum this week. The pressure is on me by Jamie's design and probably what Shell's will look like, so I don't want an ugly looking emdrive 
I will probably run a live webcam for the initial test where I can do a test stand walk-around and frustum reveal at one time. The initial powered test will have the emdrive pointing down to establish a baseline reading for power-on. Lorentz forces will be the only thing I would expect to see and I am using Mr. Li's advice plus new things to mitigate it.
Each direction (there will be 6) will have 20 datasets of about 20 minutes each run. Somebody is going to be very busy with 10's of thousands of data points... 
Best estimate for live webcam test/walkaround this Saturday 7 PM EST 5/28/16. If anything changes, will advise.
You get thrust, there is NO ugly! Good Luck and God's Speed.
Shell
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#2677
by
FattyLumpkin
on 23 May, 2016 15:57
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Monomorphic, "FEKO LITE" is no longer available, so full a version or more of the whole enchilada would have to be purchase. (Assuming one can buy various versions.) It's nice to hear from you. Good luck with your experiments + Looking forward to your results FL/K
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#2678
by
Monomorphic
on 23 May, 2016 16:11
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First VNA results from my old TE311 frustum. Not very good, and physical tuning just seemed to make it worse. Physical tuning did nothing to the RL peak frequency, though it did have other effects at different frequencies not shown here. It also looks like I have two modes very near one another. I could remove the tuning section and solder on the small end-plate to see if that improves things, but I think it's best to move on to a new frustum.
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#2679
by
Monomorphic
on 23 May, 2016 16:21
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First VNA results from my old TE311 frustum. Not very good, and physical tuning just seemed to make it worse. Physical tuning did nothing to affect the RL peak frequency, though it did have other effects at different frequencies not shown here. It also looks like I have two modes very near one another. I could remove the tuning section and solder on the small end-plate to see if that improves things, but I think it's best to move on to a new frustum.
Dual resonance mode is perhaps not a bad thing since the magnetron is wideband.
Good point. I'm going to run a number of tests on it before another frustum is ready. I need to get those two modes in the 2.445Ghz - 2.45Ghz range. Maybe I can try some dialectric inserts as well.
