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#3080
by
meberbs
on 23 Feb, 2016 13:21
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I have to run in a bit. Just thought I would point this out:
A photon rocket with energy output of 299792458 watts.
Accelerates a 1 kg spacecraft from 100,000 km/s to 100,001 km/s
Under KE=1/2m*v^2 the kinetic energy of the craft increases by 100,001 joules.
This equation is not valid at a third of the speed of light, you need special relativity equations. (That is not the main problem with your analysis, since you could have used 10 m/s instead)
Given the equation N=W/c one of those joules of energy can be accounted for the redshift of light due to imparting momentum on the craft. No matter how fast the craft is going, an observer directly behind it moving in the same direction at the same speed will always see the light being emitted at a redshifted by a frequency sufficient to remove the energy being turned into motive force.
This is not how it works, the difference in energy of the photons emitted in the spacecraft frame and the energy of the photons in the "rest" frame is irrelevant, since energy is not conserved between reference frames. An observer sees energy from the fuel source (say fusion for example) turn into a combination of energy of the photons and kinetic energy of the spacecraft (plus possibly waste heat, etc.)
Given that we are talking about relativistic velocities, fusion releases energy by measureably reducing the rest mass of the fuel, but the increased kinetic energy of the spacecraft will balance this with the increased relativistic mass (minus the energy expelled in the form of photons)
All values for measured energy would be different in different reference frames. You have to do
ALL energy calculations in a single frame.
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#3081
by
Mulletron
on 23 Feb, 2016 13:33
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There's a ton of fake free energy machines on YouTube. Magnets don't do work and gravity is a conservative field.
This one is just a clever under unity gadget, not a perpetual motion machine as some would claim. Friction and magnetic field weakening eventually stops the toy, but think its useful to spark a kids imagination. I used to be a judge at annual science fairs at my kids school...have a soft spot for gadgetry I guess.
There's still value in these things because they make you think.
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#3082
by
CW
on 23 Feb, 2016 13:58
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There's a ton of fake free energy machines on YouTube. Magnets don't do work and gravity is a conservative field.
This one is just a clever under unity gadget, not a perpetual motion machine as some would claim. Friction and magnetic field weakening eventually stops the toy, but think its useful to spark a kids imagination. I used to be a judge at annual science fairs at my kids school...have a soft spot for gadgetry I guess.
There's still value in these things because they make you think.
Ha! I once designed and built a mechanical machine, that was supposed to get energy out of centrifugal forces, feed the energy back into the cycle and keep it going. Of course the whole free energy thing didn't work out.. but it was a fantastic learning experience in mechanical engineering and overcoming profound misconceptions. Nowadays, it could easily serve as a toy for free energy dreamers to get their dreams shattered (for free!) and understand what really is going on. I think one can only appreciate conservation of energy, when having played around with it for good measure. Reading 'energy conservation' from books and then just believing it with zero critical stance, is not better than believing in flying spaghetti monsters with meat balls creating the world in six minutes.
I should dust the machine off once in a while. In case a random free energy person pops in
.
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#3083
by
rfmwguy
on 23 Feb, 2016 14:54
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Always a good idea to build and find out for yourself there's no free energy lunch. Guess its what fascinates me about the emdrive. Lots of energy going in, many assuming near 100% of it is lost to heat. If photons weren't so "ghostly" I'd have moved on a long time ago. There's just enough unknowns to keep my interest. The heat conversion troubles me. Thermal cam vids of my observational tests showed very little thermal rise of the cavity...all was around the magnetron and where it came into contact with the cavity. So guess I'm searching for evidence of direct heating based on photon absorption (losses) in copper. Found little so far outside of the mag assembly. Shells mag is remote. Anxious to see thermal pics of the cavity under power. Our math experts here could calculate surface area, mass and temp rise of the cavity and give us a pretty good idea what percentage of energy is lost to heat. Higher cavity Q would naturally have less heating.
Off to cut some copper...
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#3084
by
zen-in
on 23 Feb, 2016 17:10
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A lot of us emdrive types are gadget minded and we've discussed gravity and magnetism at length...so to keep us all in a clever mood, here's a gravity and magnetism demo that would make a fun science project for our kids and grandkids. Think gravity, mass and em:
The base looks awful thick. I wonder what is under it. Could there be some batteries and a coil that gets pulsed off and on? When pulsed on the steel ball saturates. This stops the attraction to the permanent magnet. The ball falls under the influence of gravity, making the wheel turn. The coil switches off and the ball rolls up the wheel, attracted to the permanent magnet again. You can see the ball moving up and down the track slightly even though the permanent magnet's position is fixed.
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#3085
by
Notsosureofit
on 23 Feb, 2016 17:33
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FYI:
http://www.nature.com/articles/srep22018Direct observation of negative-index microwave surface waves
Abstract
Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon.
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#3086
by
cee
on 23 Feb, 2016 17:55
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Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
Thank you rq3, this is what I was suggesting, that vibration (or other mechanical distortion) could briefly alter the resonant frequency of the cavity and bring it close enough to resonance, momentarily, to allow it to lock to the oscillator.
Which raises the next question, does resonance lock within a waveguide, allowing sustain of a signal at a slightly different frequency to its natural frequency. And if so, to what extent does this alter Q from that of an otherwise identical waveguide whose natural frequency is perfectly tuned to its oscillator?
Even with a thermally stabilized magnetron with a clean DC source it takes the heater ~4 seconds to stabilize it's output until the heater turns off. Until that time the signal is jittery all over the spectrum. This alone slams the frustum in and out of resonance lock. You can literally hear it lock and unlock during that time as the VSWR changes.
Got my magnetron finished off and will be doing some testing very soon. The reason for the cooling scheme is to cool the magnetron better over longer runs and stabilize frequency drift.
Back to work...
Shell
Shell, there is an art to liquid cooling of these tubes as well. Your coolant jacket is in contact with the maggie anode and thus at a very high potential, ~5 kv. You need to take special precautions to insulate it. Here is a link to a good discussion on water cooling microwave tubes.
http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1985/04/page32/index.html
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#3087
by
rfmwguy
on 23 Feb, 2016 18:15
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Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
Thank you rq3, this is what I was suggesting, that vibration (or other mechanical distortion) could briefly alter the resonant frequency of the cavity and bring it close enough to resonance, momentarily, to allow it to lock to the oscillator.
Which raises the next question, does resonance lock within a waveguide, allowing sustain of a signal at a slightly different frequency to its natural frequency. And if so, to what extent does this alter Q from that of an otherwise identical waveguide whose natural frequency is perfectly tuned to its oscillator?
Even with a thermally stabilized magnetron with a clean DC source it takes the heater ~4 seconds to stabilize it's output until the heater turns off. Until that time the signal is jittery all over the spectrum. This alone slams the frustum in and out of resonance lock. You can literally hear it lock and unlock during that time as the VSWR changes.
Got my magnetron finished off and will be doing some testing very soon. The reason for the cooling scheme is to cool the magnetron better over longer runs and stabilize frequency drift.
Back to work...
Shell
Shell, there is an art to liquid cooling of these tubes as well. Your coolant jacket is in contact with the maggie anode and thus at a very high potential, ~5 kv. You need to take special precautions to insulate it. Here is a link to a good discussion on water cooling microwave tubes. http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1985/04/page32/index.html
Good suggestion but pretty sure outer case of mag is ground potential as cooling fins connect from there to ground Yoke. Always worth checking tho...
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#3088
by
cee
on 23 Feb, 2016 19:05
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Shell
[/quote]
Shell, there is an art to liquid cooling of these tubes as well. Your coolant jacket is in contact with the maggie anode and thus at a very high potential, ~5 kv. You need to take special precautions to insulate it. Here is a link to a good discussion on water cooling microwave tubes.
http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1985/04/page32/index.html[/quote]
Good suggestion but pretty sure outer case of mag is ground potential as cooling fins connect from there to ground Yoke. Always worth checking tho...
[/quote]
Yes, Dave that should be the case, On these setups the anode is at ground but positive with respect to the cathode filament which is at ~-5kv. I was thinking of a normal setup where the anode is at full B+.
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#3089
by
SeeShells
on 23 Feb, 2016 20:48
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Shell
Shell, there is an art to liquid cooling of these tubes as well. Your coolant jacket is in contact with the maggie anode and thus at a very high potential, ~5 kv. You need to take special precautions to insulate it. Here is a link to a good discussion on water cooling microwave tubes.
http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1985/04/page32/index.html[/quote]
Good suggestion but pretty sure outer case of mag is ground potential as cooling fins connect from there to ground Yoke. Always worth checking tho...
[/quote]
Yes, Dave that should be the case, On these setups the anode is at ground but positive with respect to the cathode filament which is at ~-5kv. I was thinking of a normal setup where the anode is at full B+.
[/quote]
I thought about that Cee and you know
I highly respect anything you post here. Great link!!! Thanks!
If this was the case then the aluminum cooling vanes would be isolated and not connected to the ground return by being bracketed to the side walls of the magnetron support frame. I have also planned not to change that that and left the copper tubes long enough to keep that pathway in the circuit by clamping the lines off to the outer frame just like the aluminum fins were. The extra support doesn't hurt either. I may run another copper tube along and on the outside of the current one, but that's TBD.
THANKS GUYS!!!
Shell
PS: No Drive work today, 12 inches (or for others not on inches 300mm) of wet, heavy, back breaking snow (fixed)... glad I'm young at heart.
PSS: Added: The pump I have will pump ~ 1 GPM through the radiator which I have a fan running through. If testing proves this isn't enough then I'll stabilize it even more with another wrap of copper tubing and another radiator. If this isn't enough then I'll dump the entire radiator(s) into a large bucket of water and ice. If that's not enough I have spare radiators from cars sitting around and I'll add Pyrolytic Graphite Sheets to the outside of the magnetron... but I don't think I'll need to worry that far ahead. . . yet.
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#3090
by
Mulletron
on 23 Feb, 2016 22:16
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This made me think too. Question, is the physical meaning behind this because friction is a non-conservative force? Or is something else happening?
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#3091
by
zen-in
on 23 Feb, 2016 22:46
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This made me think too. Question, is the physical meaning behind this because friction is a non-conservative force? Or is something else happening?
I'll stick to conventional sailboats. They are easier to control. What is happening in the video is the air blast from the fan bounces off the sail. With no sail the thrust would be F and the boat would go backwards. By bouncing the air blast off the sail the thrust is -2F (approx.). There is no contribution from the suction side of the fan.
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#3092
by
ddunham
on 23 Feb, 2016 23:01
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The base looks awful thick. I wonder what is under it. Could there be some batteries and a coil that gets pulsed off and on? When pulsed on the steel ball saturates....
Unnecessary to tell for certain, but based on the sounds of this (and another similar video) and the awkward way the magnet appears to be held, I suspect forced air from the magnet holder. It may contain a compressed air cartridge, or could obscure an air line run from elsewhere.
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#3093
by
rfmwguy
on 23 Feb, 2016 23:37
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When local machine shops quote too high or don't get back to me, just have to do it myself. Small diameter 1/8 inch copper plate for NSF-1701A frustum. Tools used; compass, jigsaw, grinder, file, sandpaper and rotary polisher. Wish I had a lathe...
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#3094
by
spupeng7
on 23 Feb, 2016 23:49
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There's a ton of fake free energy machines on YouTube. Magnets don't do work and gravity is a conservative field.
This one is just a clever under unity gadget, not a perpetual motion machine as some would claim. Friction and magnetic field weakening eventually stops the toy, but think its useful to spark a kids imagination. I used to be a judge at annual science fairs at my kids school...have a soft spot for gadgetry I guess.
There's still value in these things because they make you think.
The years I wasted building gyroscopes in the hope of detecting thrust, turned out not to be wasted. When emdrive came along I had a grasp of so many technicalities related to detecting thrust, and a gyro inspired diploma in engineering. Now the critics can have me, it will never hurt as much as those desperate gyro days
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#3095
by
rfmwguy
on 24 Feb, 2016 03:08
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Nearly 400,000 views for emdrive T6. Impressive. Thread is getting up there in page count. Be sure to alert me when nsf user warptech's paper hits the british interplanetary journal, we'll start T7 with it to congratulate him.
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#3096
by
Mulletron
on 24 Feb, 2016 03:23
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About the blowing your own sail video and why it got my wheels turning about EmDrive. I'm not sure if this makes sense yet. I've been working on the "secondary" which is the matter in the frustum. (Side note, I'm feeling kind of dumb for dumping the non-conservative electric field and going straight to the non-conservative gravitoelectric field. I'll save the gravity stuff for extra credit. The importance of the curl came to me in the wrong order.)
Here's what I have rattling around. I was thinking about the relationship between heat and kinetic energy.
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/kintem.htmlA molecule incident on the sail, after the inelastic collision, gives some momentum to the sail and gives up heat. The molecule after collision is slower and colder.
Now enter the EmDrive, same concept with a cavity wall being the sail. The cavity walls have a cold side (outside) and a hot side. After all the electromagnetic, quantum gravity, non-conservative yada yada business is over, at the end of the day it's starting (we'll see) to look like to me that the EmDrive is just a heat engine. It doesn't seem to work when there's no "stuff" in the cavity.
So can all this thrust be explained by thermodynamics? I know from Eagleworks thermal camera pics that the temperature is not uniform across the cavity.
Is anyone here really good with thermodynamics stuff? It's not my thing.
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#3097
by
rfmwguy
on 24 Feb, 2016 03:36
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Thermal engine is possible since we are still early in the game. Recall discussions about the pioneer anomaly and its thermal causes. Thought there might be a link several threads ago...never followed up on it. Got too busy planning and building test stand and first unit.
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#3098
by
zellerium
on 24 Feb, 2016 04:14
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Here are the latest and greatest simulations I've made:
any feedback is welcome!
Solidworks tour coming soon...
Hoping we have time to build it before we graduate!
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#3099
by
Tcarey
on 24 Feb, 2016 04:27
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I'm curious about the heat related discussions creating unaccounted for thrust errors.
How much of the RF is being converted into heating the frustrum? Preferably described in watts.
I am wondering why there hasn't been a discussion of placing a heating coil of the appropriate size inside a frustrum and directly measuring the effects. I realize such a measurement would not take into account the Lorentz forces of a powered on Maggie, but at least that should give a handle on how heating affects the particular setup being measured. That would include the effects of beam lengthening, hot air currents, hot air lift on the top lip etc.
Am I missing something here?
I greatly admire what this group is doing. I also have read every post in 6 threads. I'd like to say I understood all that I read, but .....
.
