mach thrusters

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GIThruster
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Postby GIThruster » Tue Dec 21, 2010 12:37 am

Diogenes wrote:I'm a bit confused. From what I recall reading, the Mechanical transfer characteristics have been a big problem with any sort of Stacked design. I was thinking that your plates need to be chemically bonded to your dielectric to reduce this problem as much as possible.


Yes. In fact, in order to avoid the issues of acoustic impedance reflections, etc. we intended to make at least 4 attempts through various means. I have 4 of these wafers. Our first attempt intended to connect the PZT discs, one on each side; to the wafer with cyanoacrylate, since CA has fill ability smaller than the imperfections on both the wafer and the disc--it should be transparent to acoustics since there is no serious "barrier" there. The sides of the discs are then connected to the wafer electrodes with silver epoxy, but said epoxy is not between, the electrode on the disc and that on the wafer.

We have three other iterations to try if that doesn't work. Of course, the assembled stack, disc-wafer-disc; also has to be held inside a cage to stop the component parts from flying apart, and to provide the proper electrical connections.

If you're seriously interested, shoot me a note with a couple sentences of bio, your skill set, background and interest, and I'll forward it to Jim, see if I can get you on the technical distribution list. We haven't had any technical distributions to speak of this season, but I expect this to change very soon.
Last edited by GIThruster on Tue Dec 21, 2010 1:40 am, edited 2 times in total.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

GIThruster
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Joined: Tue May 25, 2010 8:17 pm

Postby GIThruster » Tue Dec 21, 2010 12:41 am

Diogenes wrote:
I suspected that's what the large bandwidth was intended for and why this might be thought of as complicated by a PHD. The impedance will change as you change frequency, and so your amplifier will experience a change in it's loading characteristics as you attempt to find the "Sweet spot."

I still don't see it as a deal killer. Impedance matching is mostly important to insure that power transfers efficiently. You can still transfer power with an impedance mismatch, you will just be dealing with losses. Again, as efficiency ought not to be of primary concern, I am thinking that a big enough heat sink would tolerate any mismatch. Another issue might be eliminating harmonics and parasitics. I'm thinking that if the leads between the drivers and the capacitor are kept short enough, this shouldn't be much of a problem at these low frequencies.


This is an issue all the EE's are not in complete agreement about. Certainly, if you are not continuously matched as you sweep, then you'll have different power into the thruster at different frequencies, and you'll have a very difficult time determining where the natural resonance and maximum thrust is. Also, mismatching causes lots of rf flying around which is not good for your instrumentation. Since we planned to use a Mettler H20 and it is entirely mechanical, not so much trouble as could be, but. . .rf is rf. It gets everywhere. :-)
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Diogenes
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Postby Diogenes » Tue Dec 21, 2010 3:43 pm

GIThruster wrote:
Diogenes wrote:
I suspected that's what the large bandwidth was intended for and why this might be thought of as complicated by a PHD. The impedance will change as you change frequency, and so your amplifier will experience a change in it's loading characteristics as you attempt to find the "Sweet spot."

I still don't see it as a deal killer. Impedance matching is mostly important to insure that power transfers efficiently. You can still transfer power with an impedance mismatch, you will just be dealing with losses. Again, as efficiency ought not to be of primary concern, I am thinking that a big enough heat sink would tolerate any mismatch. Another issue might be eliminating harmonics and parasitics. I'm thinking that if the leads between the drivers and the capacitor are kept short enough, this shouldn't be much of a problem at these low frequencies.


This is an issue all the EE's are not in complete agreement about. Certainly, if you are not continuously matched as you sweep, then you'll have different power into the thruster at different frequencies, and you'll have a very difficult time determining where the natural resonance and maximum thrust is.



I thought of that. It can be manually corrected by creating a look-up table for calibrating the impedance and drive so that it compensates for the changes as you vary the frequency, or someone could write a bit of code to create the compensation as a software component of the driver code.


In other words, modify your driver program to do impedance matching frequency correction on the fly. If the characteristics of the capacitor are predictable, then it should be easy enough to incorporate an equation in the driver software to modify the output waveform amplitude to compensate for the impedance changes.

Might take a bit of trial and error to make sure it's consistent across the entire rage of frequencies, but that's what tinkering is for! :)


GIThruster wrote: Also, mismatching causes lots of rf flying around which is not good for your instrumentation. Since we planned to use a Mettler H20 and it is entirely mechanical, not so much trouble as could be, but. . .rf is rf. It gets everywhere. :-)



The RF problem could be a SERIOUS problem. When you have 200 amp pulses at 1-2 mhz, you are going to HAVE Radiant RF, pretty much regardless of what you try to do to get rid of it. You can suppress it, but making it play nice with sensitive balances or other instrumentation might be a difficult problem.

I recall reading about the attempt by John Cramer's test of the Mach Principle with his "Mach Guitar" and thinking to myself, I will be very shocked if that experiment actually works. The Drive levels were so high I thought the system couldn't help but suffer from some sort of feedback problem.

I looked for years for some word of his results, and finally I found where he said the results were inconclusive because the experiment seemed to be plagued with feedback problems. :)

One more thing, The system needs to be in mechanical but not electrical resonance. If it goes into electrical resonance you will easily exceed the 50 volt dialectric breakdown threshold. I see no reason why the system won't work with just the mechanical aspects of it resonant.

On the other hand, if it becomes mechanically resonant, the varying thickness of the dielectric may also cause the varying voltage on the plates to exceed the 50 volt threshold. This might require that it be driven at a lower amplitude than originally anticipated.

AcesHigh
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Postby AcesHigh » Tue Dec 28, 2010 12:37 am

as for ME Effect, can someone (maybe StarDrive) comment on this section of the Wikipedia article on Woodward Effect?
The hypothesis is also related to the Nordtvedt effect proposed by Kenneth L. Nordtvedt from Montana State University, who observed that some theories of gravity suggest that massive bodies should fall at different rates depending upon their gravitational self-energy. This would violate the strong equivalence principle that the laws of gravitation are independent of velocity and location, a principle considered fundamental by many theoretical physicists.[14] The Lunar Laser Ranging Experiment has shown that if the Nordtvedt effect exists at all, it is extremely weak.

chrismb
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Postby chrismb » Tue Dec 28, 2010 1:11 pm

Is there a straightforward schematic of such a 'thruster' somewhere so that the build can be attempted by someone else?

GIThruster
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Postby GIThruster » Tue Dec 28, 2010 11:50 pm

chrismb wrote:Is there a straightforward schematic of such a 'thruster' somewhere so that the build can be attempted by someone else?


Chris, anyone who wants to be involved in M-E technology is invited to be so involved. However, this stuff is seriously complex and complicated. If someone wants to do M-E tech, they need to be able to give themselves to huge amounts of study and cooperation with those doing the work.

Just saying--anyone who wants to devote their time and effort to the M-E work, has a way open. They need to be able to work with those doing the work. If they're so able, there is lots of work to do.

Self-agrandizers look somewhere else. This is a group effort, not the effort of someone who thinks with meager skills, they'll somehow WOW the world and make a name for himself/herself.

Learn/work/accomplish. . .together, openly if you have the time and energy.

Otherwise, you're not the type we need involved in the work.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

D Tibbets
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Postby D Tibbets » Wed Dec 29, 2010 12:53 am

That is a very evasive answer to the question Chrismb asked.

Dan Tibbets
To error is human... and I'm very human.

GIThruster
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Postby GIThruster » Wed Dec 29, 2010 1:08 am

Okay, Dan. Please formulate the question as you like and I'll do the best to answer.

Paul can come answer more technical issues as you like.

Fact is, peeps don't really understand the details of M-E physics.

Anyone willing to give him/her-self to such understanding, is welcome in our ranks.

All interested parties WELCOME.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

D Tibbets
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Postby D Tibbets » Wed Dec 29, 2010 1:24 am

I neither have the desire or competence to pursue this very far, but for someone asking a question, the appropriate response is : "I don't know", "Here is a reference you can pursue", "Here is a site that might lead you to more information", "Sorry, the information is propitiatory", ... even expresing a reluctance to share information due to previous perhaps unreasonable criticisms or fatigue about the topic is reasonable, but
to belittle the questioner is not appropriate. This is actually very common. It occurs in medicine, engineering, various institutions, and anything which can claim some speciality.

It all boils down to "There are no stupid questions, only stupid answers".

Dan Tibbets
To error is human... and I'm very human.

chrismb
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Postby chrismb » Wed Dec 29, 2010 1:37 am

Thanks Dan. You said that far more tactfully than I'd have done if I'd been the first to reply!

Basically it looks like GIT is saying you can only build a working device if you believe in it. A kind of 'Peter Pan' device?

Betruger
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Postby Betruger » Wed Dec 29, 2010 2:53 am

Dan - Proprietary :)
Chris - Till P.March comes around, you can find some high level (probably pretty vague for you, but maybe better than nothing) diagrams in some of the docs attached in that "propellantless propulsion" thread in the Advanced Concepts subforum at NASASpaceflight.

KitemanSA
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Location: OlyPen WA

Postby KitemanSA » Wed Dec 29, 2010 1:47 pm

Link?

GIThruster
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Postby GIThruster » Wed Dec 29, 2010 6:11 pm

Diogenes wrote:
GIThruster wrote: Also, mismatching causes lots of rf flying around which is not good for your instrumentation. Since we planned to use a Mettler H20 and it is entirely mechanical, not so much trouble as could be, but. . .rf is rf. It gets everywhere. :-)



The RF problem could be a SERIOUS problem. When you have 200 amp pulses at 1-2 mhz, you are going to HAVE Radiant RF, pretty much regardless of what you try to do to get rid of it. You can suppress it, but making it play nice with sensitive balances or other instrumentation might be a difficult problem.

I recall reading about the attempt by John Cramer's test of the Mach Principle with his "Mach Guitar" and thinking to myself, I will be very shocked if that experiment actually works. The Drive levels were so high I thought the system couldn't help but suffer from some sort of feedback problem.

I looked for years for some word of his results, and finally I found where he said the results were inconclusive because the experiment seemed to be plagued with feedback problems.


Yes well Cramer had the sorts of issues you describe but the real issue is he ran out of funding. IIRC, he was working with a NASA grant and it was for a specific period of time. When that time ran out, the project closed. Given more time I suspect he would have solved the rf issues.

The reason for using a Mettler H20 is that it is a purely mechanical balance--no electronics to be messed up with flying rf. You still want to shield the thruster, and any electrical instrumentation, but personally I would not worry about shields until you see thrust. Once you have a signal you go about removing any possible spurious causes. That can take time. Eventually you want vacuum. However, you don't necessarily need to supply that yourself. If you have what seems an authentic signal and it maintains after shielding, etc., then probably it's worth using another test setup that already has vacuum, than in paying the price of your own vacuum system. You could for example take the entire setup to Fullerton and put it on the Arc Lite balance. I'm just guessing but I'd imagine Jim would be very accommodating should someone get a large thrust signature.

There is one trouble with the Mettler. If you're running DC, then you could have magnetic coupling since the Mettler is metal. The way around that is a Mu metal cage. Before building a cage though, you can simply wave bits of Mu metal around to see if it changes a thrust signature. If it doesn't, you know you don't have coupling and you know you don't need a cage.

Likewise you can work incrementally with vacuum. Once you have a thrust signature you need vacuum to eliminate the possibilities of thermal and ionic wind. You can for this use a relatively low vacuum setup, because if you have these spurious effects, they will scale with even E-3T which you can get with a cheap Welch roughing pump. If you get the same thrust signature at room pressure as you do at E-3T, you know you don't have ionic wind or thermal contributions, and you don't then even need to bother with your vacuum system during further testing. This is why I suggest people not worry too much about building expensive polycarb vacuum systems with thousands invested in pumps for E-7T. You simply don't need it for most tests and others have that equipment.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

D Tibbets
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Joined: Thu Jun 26, 2008 6:52 am

Postby D Tibbets » Wed Dec 29, 2010 8:04 pm

A link for some information about Mach Thrusters,


http://nextbigfuture.com/2009/09/mach-e ... march.html

with a sub link to a paper by Woodward

http://physics.fullerton.edu/~jimw/staif2000.pdf

Dan Tibbets
To error is human... and I'm very human.

Diogenes
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Joined: Mon Jun 15, 2009 3:33 pm

Postby Diogenes » Wed Dec 29, 2010 8:23 pm

GIThruster wrote:
chrismb wrote:Is there a straightforward schematic of such a 'thruster' somewhere so that the build can be attempted by someone else?


Chris, anyone who wants to be involved in M-E technology is invited to be so involved. However, this stuff is seriously complex and complicated. If someone wants to do M-E tech, they need to be able to give themselves to huge amounts of study and cooperation with those doing the work.

Just saying--anyone who wants to devote their time and effort to the M-E work, has a way open. They need to be able to work with those doing the work. If they're so able, there is lots of work to do.

Self-agrandizers look somewhere else. This is a group effort, not the effort of someone who thinks with meager skills, they'll somehow WOW the world and make a name for himself/herself.

Learn/work/accomplish. . .together, openly if you have the time and energy.

Otherwise, you're not the type we need involved in the work.


I think that is the gist of my difficulty. I simply don't have the time or energy to spare to pursue this. It is a very interesting area of research, but I am simply too busy just taking care of my responsibilities to undertake something of this difficulty level right now.


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