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#1140
by
Freddled Gruntbuggly
on 29 Dec, 2016 21:37
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Hello, I have been quietly watching this subject for some years now with great interest (and hope). I have no engineering or physics background so I hope I am not asking a stupid question here, but regarding TT's rotary rig, would the laptop's exhaust not generate measurable/unwanted air currents in this design?
Keep up the great work everyone.
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#1141
by
Left Field
on 29 Dec, 2016 22:03
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Hello, I have been quietly watching this subject for some years now with great interest (and hope). I have no engineering or physics background so I hope I am not asking a stupid question here, but regarding TT's rotary rig, would the laptop's exhaust not generate measurable/unwanted air currents in this design?
Keep up the great work everyone.
The diagram says it is a fanless laptop and uses a solid state drive, so there are no moving parts. It would still generate heat of course and perhaps that is why he mentioned that it will be in sleep mode (but with the USB port still being active).
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#1142
by
flux_capacitor
on 29 Dec, 2016 22:19
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Thruster project Google Drive updated with images of the various electronics and FC's latest drawing of the "Book Shelf and Piano Wire Rotary Test System" plus Emmett Brown's excellent videos on the movement speed of an silimar test system with 10mN and 2mN applied.
https://drive.google.com/open?id=0B7kgKijo-p0iT0VsSmV2MXl1djQ
The thruster dimensions are being optimised to copy the Df 0.844 design of the Demonstrator thruster but a bit longer to achieve TE013 resonance at 2.45GHz. This also increases Qu and thruster surface area for heat radiation.
...
Are you planning to keep the bottom and top diameters the same (259 and 159 mm) and vary the height above 288 mm to bring the original 2.4 GHz TE013 to 2.45GHz?
You are simulating another project of TheTraveller (
EmDrive Mark 3-7) not related to the current rotary experimental setup, which will instead use a slightly extended Demonstrator Thruster.
Also, try to trigger TE013 mode with a 1/4 wave stub antenna (and not with a loop antenna) placed 1/4 guide wavelength away from the big end,
along the frustum axis sticking out from the side wall and into the max E-field of the centre of the TE013 lobe. The stub is easier and cheaper to build and will not burn with only 8W of power.
Shawyer's Demonstrator big end diameter was 280 mm, small end 149 mm, with an axially tunable length between 187 and 317 mm.
Phil, what will be your fixed length?
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#1143
by
oyzw
on 29 Dec, 2016 23:56
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Thruster project Google Drive updated with images of the various electronics and FC's latest drawing of the "Book Shelf and Piano Wire Rotary Test System" plus Emmett Brown's excellent videos on the movement speed of an silimar test system with 10mN and 2mN applied.
https://drive.google.com/open?id=0B7kgKijo-p0iT0VsSmV2MXl1djQ
The thruster dimensions are being optimised to copy the Df 0.844 design of the Demonstrator thruster but a bit longer to achieve TE013 resonance at 2.45GHz. This also increases Qu and thruster surface area for heat radiation.
...
I've been working on exciting your frustum using a 50 ohm loop through the bottom, but haven't gotten below an S11 of -2dB yet. The loop keeps throwing off the bottom E field node. I've been using spherical end caps but the flat ends aren't much different.
Are you planning to keep the bottom and top diameters the same (259 and 159 mm) and vary the height above 288 mm to bring the original 2.4 GHz TE013 to 2.45GHz?
Your coupling design is not appropriate. The antenna ring should be in the side wall, near the large end position.
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#1144
by
Tcarey
on 30 Dec, 2016 02:16
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Very energy wasteful to feed 12.8Vdc (4x Li Ion batteries) into a 5Vdc regulator. Much better to feed 6.4Vdc (2 Li Ion batteries) into the regulator as less heating of the regulator.
EE 101.
Not quite. It really depends on many factors:
http://www.ti.com/lit/an/slyt293/slyt293.pdf
3 pin reg + 1 resistor = KISS. Switching reg, which I have designed and build too many = pain in the butt. Much simpler to feed 6.4Vdc into a LDO reg to get a nicely regulated 5Vdc while only needing a series resistor.
But hey when you build your KISS EmDrive, please feel free to change it and to put in switchers.
These bucking regulators are dirt cheap and will decrease the amount of heat generated. I have used them in various projects and found them to work well. They have a variety of output voltages available and different current limits. You might find one of these to your liking.
https://www.pololu.com/category/131/step-down-voltage-regulators
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#1145
by
dustinthewind
on 30 Dec, 2016 02:19
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The other patent "An Electromagnetic Thruster Cavity Based on Periodic Structure" CN105781921A presents an RF resonant cavity thruster made of recursive stacked short cavities connected in series. The thruster can be made of square or circular plates, each one having a notch letting RF pass through to the next resonant chamber, and so forth.
...
I don't really understand how this particular cavity has anything in common with a frustum or some asymmetry. However what caught my attention was the series of cavities connected as if to pass on radiation from one to the next. Is this supposed to be like one cavity resonates the light till it red-shifts to a point it no longer resonates in that cavity and then the radiation passes to the next resonate cavity that matches that frequency.
If so this may enhance the spectrum that is allowed to resonate if the frequency is continuously dropping.
My main problem with it is the drawings don't make a lot of sense to me.
This cavity is related to the other patent (please compare the numbers ). An asymmetry should be present for the surface currents, the way along the curved face is much longer than at the flat surface while the total resistance of each path is given by an integral over the skin penetration depth times the resistance of the copper and the path length as well as the temperature of the local resistor. Because of the temperature grows faster at the middle bottom section (higher current density) the resistance grows faster in this region.(Not sure if this construction is usable fore constant thrust generation in space 
)
Does it make sense? 
What you describe sounds like a sort of bandpass filter. The periodic structure may better compared to the slotted cannae device.
I wasn't interested in the half cylindrical cavity. Just the odd multi-cavity device that didn't seem to have any asymmetry. Not sure the half cylinder has the necessary asymmetry itself to induce some change in the radiation wavelength as if it is approaching cutoff.
For all we know it could be something to throw us off. Not that I am implying that is the case. Just considering that possibility.
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#1146
by
dustinthewind
on 30 Dec, 2016 02:22
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Thruster project Google Drive updated with images of the various electronics and FC's latest drawing of the "Book Shelf and Piano Wire Rotary Test System" plus Emmett Brown's excellent videos on the movement speed of an silimar test system with 10mN and 2mN applied.
https://drive.google.com/open?id=0B7kgKijo-p0iT0VsSmV2MXl1djQ
The thruster dimensions are being optimised to copy the Df 0.844 design of the Demonstrator thruster but a bit longer to achieve TE013 resonance at 2.45GHz. This also increases Qu and thruster surface area for heat radiation.
...
I've been working on exciting your frustum using a 50 ohm loop through the bottom, but haven't gotten below an S11 of -2dB yet. The loop keeps throwing off the bottom E field node. I've been using spherical end caps but the flat ends aren't much different.
Are you planning to keep the bottom and top diameters the same (259 and 159 mm) and vary the height above 288 mm to bring the original 2.4 GHz TE013 to 2.45GHz?
You might consider that clover leaf antenna (with out the tilted petals [planar leafs]) as it allows
a larger perimeter/radius of the antenna. It may allow the antenna to penetrate deeper into the electric field region of your simulation and enhance resonance.
If I remember correctly, Rodal pointed out once that putting the antenna in the greatest part of the electric field is desirable, which seemed to make sense to me. I'll try and look up where I saw this antenna on the forum some time ago.
the perimeter of even the clover leaf may not be large enough at the bottom so the antenna flux_capacitor suggests may be more desirable? I would think the top would be more desirable because the electric field at the top appears to be greatest and enhance antenna coupling with the cavity at that particular mode.(the tilted petals will enhance the transverse magnetic which doesn't appear to be what you want, which is why I recommend making flat leafs. )
It was this post here :
https://forum.nasaspaceflight.com/index.php?topic=40959.msg1609040#msg1609040 which was in response to a post from SeaShells.
The other type of antenna may also work in the side wall depending on the configuration as oyzw and flux says.
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#1147
by
SeeShells
on 30 Dec, 2016 03:45
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Thruster project Google Drive updated with images of the various electronics and FC's latest drawing of the "Book Shelf and Piano Wire Rotary Test System" plus Emmett Brown's excellent videos on the movement speed of an silimar test system with 10mN and 2mN applied.
https://drive.google.com/open?id=0B7kgKijo-p0iT0VsSmV2MXl1djQ
The thruster dimensions are being optimised to copy the Df 0.844 design of the Demonstrator thruster but a bit longer to achieve TE013 resonance at 2.45GHz. This also increases Qu and thruster surface area for heat radiation.
...
I've been working on exciting your frustum using a 50 ohm loop through the bottom, but haven't gotten below an S11 of -2dB yet. The loop keeps throwing off the bottom E field node. I've been using spherical end caps but the flat ends aren't much different.
Are you planning to keep the bottom and top diameters the same (259 and 159 mm) and vary the height above 288 mm to bring the original 2.4 GHz TE013 to 2.45GHz?
You might consider that clover leaf antenna (with out the tilted petals [planar leafs]) as it allows a larger perimeter/radius of the antenna. It may allow the antenna to penetrate deeper into the electric field region of your simulation and enhance resonance. If I remember correctly, Rodal pointed out once that putting the antenna in the greatest part of the electric field is desirable, which seemed to make sense to me. I'll try and look up where I saw this antenna on the forum some time ago. the perimeter of even the clover leaf may not be large enough at the bottom so the antenna flux_capacitor suggests may be more desirable? I would think the top would be more desirable because the electric field at the top appears to be greatest and enhance antenna coupling with the cavity at that particular mode.
(the tilted petals will enhance the transverse magnetic which doesn't appear to be what you want, which is why I recommend making flat leafs. )
It was this post here : https://forum.nasaspaceflight.com/index.php?topic=40959.msg1609040#msg1609040 which was in response to a post from SeaShells.
The other type of antenna may also work in the side wall depending on the configuration as oyzw and flux says.
http://www.antenna-theory.com/antennas/cloverleaf.phpThis should help. Position is critical and I'd recommend feeding it better than you did the loop with two vertical wires that will also act as antennas depending on the lengths. Need a coax feed to the antenna (see pictures).
Been a little busy as of late (holidays you know) and just spent the last several hours trying to catch up on critical reading and some great posts here.
Happy Holidays All,
Shell
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#1148
by
TheTraveller
on 30 Dec, 2016 05:16
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The 1st test thruster dimensions, so far, are:
BD: 0.2800m,
SD: 0.1487m
LN: 0.3244m
Df: 0.837
Mode: TE013
Freq: 2.45GHz
Qu: 60k
End plates are flat and made from single sided FR4 PCB blank. Use of the single sided pcb was done as those end plates should be very flat as opposed to what a DIYer may buy from their copper plate supplier. Plus they reduce the thruster weight. The end plates will be hand cut, drilled and very highly polished from the PCB stock
Side wall is rolled 0.5mm 101 copper with a soldered butt side wall joint. 10mm wide 1mm copper flanges will be soldered to the small and big ends of the side wall section so the end plates can be bolted to the side wall section. Hoop rings will be used to ensure a circular form and to assist side wall construction. Side wall 0.5mm copper will be laser/water cut to ensure high accuracy to the SD and that the end plates should be highly parallel to each other and orthogonal to the thruster Z axis. Will later build a few thrusters that have the 0.5mm side wall copper hand cut to compare the Qu. Hopefully the KISS esign will be able to be hand cut and hand rolled.
This design is based around the Df that Roger achieved with the Demonstrator. I took his BD of 280mm, Df 0.844 and freq 2.45 and using his Df equation obtained the SD of 0.1487. Was actually 0.14862, which I rounded up to the next 0.1mm so to allow some manufacturing tolerance.
The length (which doesn't factor into the Df equation) was then calculated to achieve TE013 resonance at 2.45GHz.
Antenna will be a 1/4 wave stub, sticking out from the side wall and into the max E field of the central TE013 lobe. Insertion depth and angle / orientation to the side wall are adjustable so to get the lowest VSWR. As the input power and E field intensity are low, due to the 8W, don't expect the end of the stub to turn into a match stick. This should be a much easier antenna to make and align than a 1/2 side wall loop.
Would appreciate those of you with other modeling tools to have a look at this design. It is NOT the EW thruster, which I will do next. Please check the freq and the Qu so I can get this design bolted down and started to be made real.
As always comments and advise are sought as I feel we all want to see this thruster doing several revs on the test bed.
Thanks,
Phil
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#1149
by
TheTraveller
on 30 Dec, 2016 06:17
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These bucking regulators are dirt cheap and will decrease the amount of heat generated. I have used them in various projects and found them to work well. They have a variety of output voltages available and different current limits. You might find one of these to your liking.
https://www.pololu.com/category/131/step-down-voltage-regulators
Thanks for that.
Nice unit:
https://www.pololu.com/product/2098However my Lorentz advisor, PhotomacNeuron, sees advantage in the two battery packs as it eliminates any Dc current loop which may occur if using a single battery pack to power both the 8W Rf amp and the Rf peramp.
Once that concern is experimentally shown to be not a concern, OK it is just how I see it, and I move forward with the KISS thruster release, for sure the 2 Rf amps will be powered from a single 4 x 3.2Vdc Li Ion battery pack and the 5Vdc supplied from the above step down regulator. Don't want DC current flowing over the coax shield.
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#1150
by
guttigor
on 30 Dec, 2016 06:23
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Heated resonance chamber will result in a convection over it. It will be asymmetrical due to the shape of the compartment. You can expect of force directed to the side. So much more than a laptop - it does not heat up evenly.
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#1151
by
TheTraveller
on 30 Dec, 2016 06:32
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Heated resonance chamber will result in a convection over it. It will be asymmetrical due to the shape of the compartment. You can expect of force directed to the side. So much more than a laptop - it does not heat up evenly.
Laptop will have it's screen closed flat to the keyboard and in sleep mode during the thruster acceleration tests. Even when operating, it doesn't get hot, just slightly warm to the touch. Hard Drive is a non moving SSD.
There will be 4 "NULL" tests done to characterise the thermal effects of every thing on the Book Shelf and their ability to cause rotation.
1) thruster small end pointed Up
2) thruster small end pointed Down
3) thruster small end pointed into the centre
4) thruster small end pointed away from the centre.
All tests started AFTER the thruster is fully powered and has thermally and resonance freq change stabilised. So there should not be any significant thermal heat change of any of the object during the active portion of the rotary tests. Will test to be sure there is no rotary effect being generated by anything during the NULL tests.
Does that address your concerns?
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#1152
by
guttigor
on 30 Dec, 2016 06:53
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Warm air will rose along the side wall of the chamber. Towards the narrower end.
Air flow will be under the computer if the hottest spot will be closer ANY edge.
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#1153
by
oyzw
on 30 Dec, 2016 07:21
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Heated resonance chamber will result in a convection over it. It will be asymmetrical due to the shape of the compartment. You can expect of force directed to the side. So much more than a laptop - it does not heat up evenly.
Laptop will have it's screen closed flat to the keyboard and in sleep mode during the thruster acceleration tests. Even when operating, it doesn't get hot, just slightly warm to the touch. Hard Drive is a non moving SSD.
There will be 4 "NULL" tests done to characterise the thermal effects of every thing on the Book Shelf and their ability to cause rotation.
1) thruster small end pointed Up
2) thruster small end pointed Down
3) thruster small end pointed into the centre
4) thruster small end pointed away from the centre.
All tests started AFTER the thruster is fully powered and has thermally and resonance freq change stabilised. So there should not be any significant thermal heat change of any of the object during the active portion of the rotary tests. Will test to be sure there is no rotary effect being generated by anything during the NULL tests.
Does that address your concerns?
How much is the power is microwave source? TE013 mode?
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#1154
by
oyzw
on 30 Dec, 2016 07:25
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These bucking regulators are dirt cheap and will decrease the amount of heat generated. I have used them in various projects and found them to work well. They have a variety of output voltages available and different current limits. You might find one of these to your liking.
https://www.pololu.com/category/131/step-down-voltage-regulators
Thanks for that.
Nice unit:
https://www.pololu.com/product/2098
However my Lorentz advisor, PhotomacNeuron, sees advantage in the two battery packs as it eliminates any Dc current loop which may occur if using a single battery pack to power both the 8W Rf amp and the Rf peramp.
Once that concern is experimentally shown to be not a concern, OK it is just how I see it, and I move forward with the KISS thruster release, for sure the 2 Rf amps will be powered from a single 4 x 3.2Vdc Li Ion battery pack and the 5Vdc supplied from the above step down regulator. Don't want DC current flowing over the coax shield.
The power of 8W is too small, the cost of purchasing 200W solid-state amplifier is not high, I can provide suppliers, the price is cheap.
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#1155
by
Freddled Gruntbuggly
on 30 Dec, 2016 10:16
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Hello, I have been quietly watching this subject for some years now with great interest (and hope). I have no engineering or physics background so I hope I am not asking a stupid question here, but regarding TT's rotary rig, would the laptop's exhaust not generate measurable/unwanted air currents in this design?
Keep up the great work everyone.
The diagram says it is a fanless laptop and uses a solid state drive, so there are no moving parts. It would still generate heat of course and perhaps that is why he mentioned that it will be in sleep mode (but with the USB port still being active).
My apologies. I glanced at the posted diagram and read TT's posts but did not enlarge the diagram to read the notations. I will get back in my box...
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#1156
by
TheTraveller
on 30 Dec, 2016 12:32
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The power of 8W is too small, the cost of purchasing 200W solid-state amplifier is not high, I can provide suppliers, the price is cheap.
8W should be more than enough if the thruster manuf is high enough quality. Predicted force is 2mN.
Watch the video of what 2mN can do on a wooden plank based torsion balance as attached.
I'm happy to consult with Dr. Chen.
No reason to use high power and thruster heating to make up for a bad design / build.
Get it right at low power and the "Expanse" with +1g crewed ships colonisation the solar system is ours.
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#1157
by
TheTraveller
on 30 Dec, 2016 12:45
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Warm air will rose along the side wall of the chamber. Towards the narrower end.
Air flow will be under the computer if the hottest spot will be closer ANY edge.
There are 4 test modes that are not expected to generate ANY rotation. They will characterise the thermal and Lorentz forces generated by ALL the items on the Book Shelf Balance Beam.
1) thruster small end pointing Up.
2) thruster small end pointing Down.
3) thruster small end pointing into the centre.
2) thruster small end pointing away from the centre.
These 4 tests will be done to show that none of the items on the Bookshelf can cause rotation if the thruster small emd is NOT pointed CW or CCW.
Please understand the only force measurement will be via F = M * A as this test rig will enable sort of Free Acceleration, for hopefully many revolutions, at least until the twisted piano wire absorbs enough reverse torque to stop the free acceleration.
What you should expect to see are several revolution as the thruster generates radial acceleration of the 10kg mass.
So no 1-2um of movement. More like many meters of movement.
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#1158
by
oyzw
on 30 Dec, 2016 12:59
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Warm air will rose along the side wall of the chamber. Towards the narrower end.
Air flow will be under the computer if the hottest spot will be closer ANY edge.
There are 4 test modes that are not expected to generate ANY rotation. They will characterise the thermal and Lorentz forces generated by ALL the items on the Book Shelf Balance Beam.
1) thruster small end pointing Up.
2) thruster small end pointing Down.
3) thruster small end pointing into the centre.
2) thruster small end pointing away from the centre.
These 4 tests will be done to show that none of the items on the Bookshelf can cause rotation if the thruster small emd is NOT pointed CW or CCW.
Please understand the only force measurement will be via F = M * A as this test rig will enable sort of Free Acceleration, for hopefully many revolutions, at least until the twisted piano wire absorbs enough reverse torque to stop the free acceleration.
What you should expect to see are several revolution as the thruster generates radial acceleration of the 10kg mass.
So no 1-2um of movement. More like many meters of movement.
I also think that even if the heating of an asymmetric object, the heat generated can not be sustained in the axial direction of the thrust
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#1159
by
rq3
on 30 Dec, 2016 13:02
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Maybe it's just me, but I find it difficult to comment on a design that consists of a verbal description that keeps changing.
A schematic would be nice, even if it is a photo of a napkin sketch.
Here you go.
Well, not the level of detail I wanted to see, but anyway...
If you "T" off the reflected power and process it, you could feed the result directly into the laptop microphone input (AD converter). The result would be the closed loop I've been advocating all along. Some simple code would let the laptop dynamically and directly achieve best VSWR even if things heat and drift. With little additional cost other than the code development time. With the addition of a cheap accelerometer or force gauge, you could easily make my "force locked loop", which would be ideal.
)