-
#400
by
SeeShells
on 22 Mar, 2016 14:49
-
Since no-one else has asked:
A) How have you measured the minimum force required to move a EMdrive-equivalent mass on that air-track? (And what is the minimum force?)
B) Do you have a way of measuring the force produced by your EMDrive, or are you just looking at a binary yes/no result from displacement?
A properly designed air track has no minimum force required to get it moving because it has zero stiction. All retarding forces it experiences (drag/friction) are dynamic and dependent on being in motion.
The air-track is pretty much binary, it either moves or it doesn't. The interferometer will allow me to do much more precise measurements of displacement. This is accomplished by counting the interference fringe patterns as they change.
Lastly, there is a third set-up mode: the White-Juday Field Interferometer. In this configuration the laser passes through the center of the frustum to look for variations in the path time.
Unless you perform this experiment in a vacuum chamber, there will be air resistance, characterized by a coefficient of drag, CD (dependent on the Reynolds number) and (approximately) the square of the velocity.
Looking at the picture of your setup, this air drag will produce a torque moment on the EM Drive, tilting the leading end of the EM Drive, because the air drag force has a moment arm around the air track support (the axis of application of the air drag force is located at a distance from the air track support), since the EM Drive is unsymmetrically located, on one side, of the air track. This moment will produce additional resistance, as well as additional aerodynamic contributions, and it will produce pressure on the air track support.
Normally one doesn't worry about such small contributions but since the forces that experimenters want to measure in these EM Drive experiments are so small (microNewtons for NASA's and Tajmar's experiments, milliNewtons for Yang's experiments), it may be worthwhile to consider their contributions in the experiment.
PS: There is also the issue of how is the EM Drive powered. Ideally it would be powered from a battery, self-integrated, as this would avoid issues due the fact that energy is transmitted from an outside source to the EM Drive (hence there is a tiny amount of momentum due to this which would only be eliminated when using a battery source in a self-integrated configuration).
There is also the issue of possible Lorentz forces from cables, and the issue of unequal heated surfaces and unequal surface areas of the EM Drive due to induction heating, producing unsymmetric thermal convection (if not tested in a vacuum): buoyancy resulting in pressure on the track, convection asymmetry resulting in line force (due to density asymmetry) and torque (due to the moment arm), and asymmetric thermal radiation asymmetry, which I will not repeat here in the interest of brevity, since they have been discussed in previous threads.
I see what your saying Dr. Rodal. But let's take a look at the air pressure and the forces that are brought to the beam and how small of an effect an accelerating drive would impact to the beam. It looks like monomorphic has a 4x4 hollow beam that the bearing surface is about 24" long. If he even inputs 10 PSI unto the hollow beam that gives a surface area of 10 PSI across one square inch. One side of the air bearing is 4x4x24 = 384 Square inches x 10PSI = 3840 pounds times 2 to include the other side 3840x2=7,680 pounds for a lifting force. He could float a truck on the beam.
The placement of the drive in the center balance point is minor the other issues. The jets aligned in rows symmetrically placed around the air beam, the carriage will have to "push" into these row of jets as it travels down the beam which will give a leading edge resistance when the carriage tries to move over it.
I might have done it a little differently using a solid hollow beam and building a large 12x24" PCV pipe airtank on top that could provide a regulated 3-4 PSI in a floating air bearing carriage assembly. Then balance the drive and hardware. This would eliminate issues that you and I just brought up.
My .02 cents is maybe worth .01 cent, but we're just being picky old fuddy dutties.
Shell
-
#401
by
rfmwguy
on 22 Mar, 2016 14:54
-
Regarding the mysteries of patents, disclosures, claims, refutations, etc: A working EMdrive is bigger than patents. You could call it a military technology, or a world-changing invention. Many groups may be jostling for position in attempts to get valuable information, or funding, while at the same time protecting their own secrets. "Dirty tricks" may happen. My advice is to be wary.
Amen to that. What is happening here is actually pretty bizzare - people are trying to replicate what would be extremely valuable technology in open cyberspace - the equivalent of a sunny open field, where every so often strangers wander up and chip in comments. Particularly interesting are the visitors who say "That's definitely not worth trying!" or "This way not that way!" when there is no publicly accepted theory of operation. Wary is definitely good, as is being wary of conspiracy theories. Nonetheless "Cui Bono?" is a very good question to bear in mind.
The hibernating author in me is fascinated by all the drama surrounding the emdrive. It would make a great book...but I'm not in a writing mode. As a builder, I am very wary of advice, especially from those who are not building or testing. It certainly is worth trying and its been a great learning experience and polishing up my rusty electromechanical skills. Just need to stress that safety is first, these things can be deadly if in the wrong hands.
-
#402
by
Monomorphic
on 22 Mar, 2016 15:10
-
I might have done it a little differently using a solid hollow beam and building a large 12x24" PCV pipe airtank on top that could provide a regulated 3-4 PSI in a floating air bearing carriage assembly. Then balance the drive and hardware. This would eliminate issues that you and I just brought up.
I'm still working on the air pressure system. Right now i'm using a simple shop vac and a PVC water valve to control the flow. It's crude, but works. However, the shop vac just can't generate the PSI past a certain point, so this air-track is limited in how much it can lift unless I switch to a more robust air system.
The whole apparatus must be balanced AND the glider must be balanced. The structure is balanced using 4 fine thread bolts attached to each foot. Works very well. The glider is balanced by hanging it by a wire.
I have no doubt there will be a lot of calibration required to get results.
-
#403
by
Monomorphic
on 22 Mar, 2016 15:13
-
A summary of other experimental small forces. There is also the issue of how is the EM Drive powered. Ideally it would be powered from a battery, self-integrated, as this would avoid issues due the fact that energy is transmitted from an outside source to the EM Drive (hence there is a tiny amount of momentum due to this which would only be eliminated when using a battery source in a self-integrated configuration).
I've always planned on going with a battery eventually. That's why I am pursuing the RF transmitter route as well. A system like that could be run with a couple of high discharge li-po RC batteries. Heck, with a 1200 watt inverter, I could run a 600 watt magnetron off RC batteries for several minutes at a time.
-
#404
by
SeeShells
on 22 Mar, 2016 15:22
-
I might have done it a little differently using a solid hollow beam and building a large 12x24" PCV pipe airtank on top that could provide a regulated 3-4 PSI in a floating air bearing carriage assembly. Then balance the drive and hardware. This would eliminate issues that you and I just brought up.
I'm still working on the air pressure system. Right now i'm using a simple shop vac and a PVC water valve to control the flow. It's crude, but works. However, the shop vac just can't generate the PSI past a certain point, so this air-track is limited in how much it can lift.
The whole apparatus must be balanced AND the glider must be balanced. The structure is balanced using 4 fine thread bolts attached to each foot. Works very well. The glider is balanced by hanging it by a wire.
I have no doubt there will be a lot of calibration required to get results.
I can see that air requirement going up very high Monomorphic when your providing air for the whole hollow beam instead of just a floating carriage.
When we did air bearing carriages for our dicing machines we didn't do the whole beam we did just the carriage and that dropped the air requirements orders of magnitude.
Fine tuning on a air bearing surface can be very fine work, you have that right.
Shell
-
#405
by
Monomorphic
on 22 Mar, 2016 16:40
-
When we did air bearing carriages for our dicing machines we didn't do the whole beam we did just the carriage and that dropped the air requirements orders of magnitude.
If I attached an air system to the glider and got thrust, critics could claim it was torque from spinning fans/motors. I've seen this mentioned about Shawyer's demonstration model and the pump for the water coolant.
It's not so much that I need a much higher PSI, it's that the air-vac is simply incapable of providing more than a few PSI. The air backs out through the fan. The frustum floats now, but once loaded with batteries, magnetron and transformer... I may need to go to a pressurized tank. Once the RF transistor amp is completed, that should eliminate the heavy transformer and magnetron.
-
#406
by
FattyLumpkin
on 22 Mar, 2016 18:07
-
Monomorphic , what does your modeling predict for "amount" expected thrust? Thanks ,
F L
-
#407
by
SeeShells
on 22 Mar, 2016 18:34
-
When we did air bearing carriages for our dicing machines we didn't do the whole beam we did just the carriage and that dropped the air requirements orders of magnitude.
If I attached an air system to the glider and got thrust, critics could claim it was torque from spinning fans/motors. I've seen this mentioned about Shawyer's demonstration model and the pump for the water coolant.
It's not so much that I need a much higher PSI, it's that the air-vac is simply incapable of providing more than a few PSI. The air backs out through the fan. The frustum floats now, but once loaded with batteries, magnetron and transformer... I may need to go to a pressurized tank. Once the RF transistor amp is completed, that should eliminate the heavy transformer and magnetron.
If you did a stand alone air tank on the top of the beam driving the carriage you could eliminate the air shooting from the rest of the beam causing issues if you drove it this way.
You can wrap the outside of the center area for strength. I've seen 100+ pound fishing line wrapped around to strengthen the walls laid in with a epoxy.
Like this
http://beamalarm.com/Documents/building_an_external_air_compressor.htmlI hope you don't mind me talking about your project.
Shell
-
#408
by
Monomorphic
on 22 Mar, 2016 18:46
-
If you did a stand alone air tank on the top of the beam driving the carriage you could eliminate the air shooting from the rest of the beam causing issues if you drove it this way.
You can wrap the outside of the center area for strength. I've seen 100+ pound fishing line wrapped around to strengthen the walls laid in with a epoxy.
Like this http://beamalarm.com/Documents/building_an_external_air_compressor.html
I hope you don't mind me talking about your project.
Shell
I actually like this idea a lot. It would be easy to incorporate into the current design. It would eliminate the air-vac and noise associated with the motor and fan.
-
#409
by
Monomorphic
on 22 Mar, 2016 18:52
-
Tuning section complete. To move the small end-plate through the tuning section simply turn the three wing nuts equally.
I hope to have the interferometer up and running soon. I have everything, I just need to figure out how to mount my beam splitter horizontally and create an adjustable mount for the laser.
-
#410
by
SeeShells
on 22 Mar, 2016 19:17
-
If you did a stand alone air tank on the top of the beam driving the carriage you could eliminate the air shooting from the rest of the beam causing issues if you drove it this way.
You can wrap the outside of the center area for strength. I've seen 100+ pound fishing line wrapped around to strengthen the walls laid in with a epoxy.
Like this http://beamalarm.com/Documents/building_an_external_air_compressor.html
I hope you don't mind me talking about your project.
Shell
I actually like this idea a lot. It would be easy to incorporate into the current design. It would eliminate the air-vac and noise associated with the motor and fan.
It would only take enough air pressure from the tank to "float" a couple thousands off the beam. I found out I could
float me standing on a flat 12"x12" air bearing on a smooth concrete floor with just a few pounds of air and surprising very little air flow.
Shell
-
#411
by
X_RaY
on 22 Mar, 2016 19:19
-
Tuning section complete. To move the small end-plate through the tuning section simply turn the three wing nuts equally.
I hope to have the interferometer up and running soon. I have everything, I just need to figure out how to mount my beam splitter horizontally and create an adjustable mount for the laser.
Hi,
is this a slot/gap between the frustum and the big end plate in your pic?
Please be aware of possible radiation through the gap using a high power level magnetron source! Such a gap can act as a kind of slot antenna. Safety first!!
Best regards
BTW nice construction, good luck!!
-
#412
by
Monomorphic
on 22 Mar, 2016 19:27
-
is this a slot/gap between the frustum and the big end plate in your pic?
Please be aware of possible radiation through the gap using a high power level magnetron source! Such a gap can act as a kind of slot antenna.
Please note that there has not yet been any soldering on the build except for some of the internal components related to the tuning section. After happy with overall tolerances, I will slightly compress the frustum using clamps, which closes any gaps, and then flow the silver solder into the gaps.
-
#413
by
Monomorphic
on 22 Mar, 2016 20:49
-
Such a gap can act as a kind of slot antenna. Safety first!!
To illustrate what X-RaY is talking about I ran a sim of my build using perfect geometry and one with 2mm gaps along one side of all major joints.
-
#414
by
Monomorphic
on 22 Mar, 2016 21:23
-
I also ran some sims using the tuning section. Based on this, I may remove the tuning section and run some tests with just the perfect geometry. I'm not so sure tuning will have much benefit for me as the dimensions were already highly optimized for TE311. The added complexity, with possible gaps may not be worth it. I can always add the tuning section later.
-
#415
by
Oakey
on 22 Mar, 2016 22:54
-
Hi Monomorphic, nice build. Do you have any info/pics of the beam splitter your using and how your detecting the interference?
-
#416
by
Monomorphic
on 22 Mar, 2016 23:23
-
-
#417
by
Oakey
on 22 Mar, 2016 23:29
-
Thanks Monomorphic. Good luck with mounting it.
-
#418
by
The_Optimist
on 23 Mar, 2016 10:55
-
-
#419
by
SimonFD
on 23 Mar, 2016 10:55
-
