Quote from: DrBagelBites on 07/08/2015 03:07 pmQuote from: SeeShells on 07/08/2015 01:52 pm@rfmwguy or any that care to answer.Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.ShellEDIT: readabilityHave we run a Meep simulation of the input signal being an oscillating signal from one frequency to another and back down again? I'm not even sure Meep can do that.Perhaps, creating something like a square wave pattern would be ideal instead of sinusoidal.A Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.
Quote from: SeeShells on 07/08/2015 01:52 pm@rfmwguy or any that care to answer.Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.ShellEDIT: readabilityHave we run a Meep simulation of the input signal being an oscillating signal from one frequency to another and back down again? I'm not even sure Meep can do that.Perhaps, creating something like a square wave pattern would be ideal instead of sinusoidal.
@rfmwguy or any that care to answer.Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.ShellEDIT: readability
Quote from: SeeShells on 07/08/2015 02:42 pmQuote from: rfmwguy on 07/08/2015 02:35 pmQuote from: SeeShells on 07/08/2015 01:52 pm@rfmwguy or any that care to answer.Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.ShellEDIT: readabilityFWIW, High Q and pure signals are where I've always tried to be, but this thing is different somehow. Before putting time/money at signal purity, CW and highest Q possible, I'm just trying to test a basic concept. There is a good chance that I'll stop there if I have null results and pass the hat to someone else. First, we take baby steps with whatever we have, then tweak it...mainly to test other's claims. So my advice is take a swing at it without over-engineering/over-thinking it. The smallest amount of positive results can lead to modifications, such as top-hat tuning, reduced power/cleaner signal, etc.You're right but I'm thinking after this very basic run. I sometimes feel that I'm pounding a nail with a large rock this first test, when I need a small hammer.Shell - have you made any progress in getting a VNA from local hams? I think a VNA may be a very useful piece of test gear, particular as the EMDrive locks in to freq/modulation and/or changes mode; particular if the data can be captured at a high enough data rate. Just FYI, here are a couple of links to a (more or less) affordable 2 port VNA.http://miniradiosolutions.com/ -the mini VNA tiny will go to 3Ghzhttp://www.hamradio.com/detail.cfm?pid=H0-013596 HRO has them for about $575. **Context Switch**"Mote in God's Eye" - one of the books I re-read every few years. Maybe the best science fiction ever - perhaps excluding Heinlein. I still want to be Sir Kevin Renner when I grow up.Herman-W5HLP
Quote from: rfmwguy on 07/08/2015 02:35 pmQuote from: SeeShells on 07/08/2015 01:52 pm@rfmwguy or any that care to answer.Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.ShellEDIT: readabilityFWIW, High Q and pure signals are where I've always tried to be, but this thing is different somehow. Before putting time/money at signal purity, CW and highest Q possible, I'm just trying to test a basic concept. There is a good chance that I'll stop there if I have null results and pass the hat to someone else. First, we take baby steps with whatever we have, then tweak it...mainly to test other's claims. So my advice is take a swing at it without over-engineering/over-thinking it. The smallest amount of positive results can lead to modifications, such as top-hat tuning, reduced power/cleaner signal, etc.You're right but I'm thinking after this very basic run. I sometimes feel that I'm pounding a nail with a large rock this first test, when I need a small hammer.
Quote from: SeeShells on 07/08/2015 01:52 pm@rfmwguy or any that care to answer.Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.ShellEDIT: readabilityFWIW, High Q and pure signals are where I've always tried to be, but this thing is different somehow. Before putting time/money at signal purity, CW and highest Q possible, I'm just trying to test a basic concept. There is a good chance that I'll stop there if I have null results and pass the hat to someone else. First, we take baby steps with whatever we have, then tweak it...mainly to test other's claims. So my advice is take a swing at it without over-engineering/over-thinking it. The smallest amount of positive results can lead to modifications, such as top-hat tuning, reduced power/cleaner signal, etc.
Quote from: rfmwguy on 07/08/2015 03:39 pm...A Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.What is your guesstimate for the date of your first test ?
...A Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.
Quote from: WarpTech on 07/08/2015 05:47 pm...Your equation for Pout is wrong.Pout = d/dt(0.5 m v2) = m v a + 0.5 v2 dm/dtWhen you leave out dm/dt, it results in your over-unity paradox. In order to have acceleration, dm/dt cannot be zero. The kinetic energy gained can never exceed the change in mass, dm * c2.ToddWhile I understand the physics I would like to offer an example that seems to violate this. An electrodynamic tether uses solar electrical power to energize a long cable that is normal to the geomagnetic field. DC power flows through the tether and then back through space with the help of charged particles.
...Your equation for Pout is wrong.Pout = d/dt(0.5 m v2) = m v a + 0.5 v2 dm/dtWhen you leave out dm/dt, it results in your over-unity paradox. In order to have acceleration, dm/dt cannot be zero. The kinetic energy gained can never exceed the change in mass, dm * c2.Todd
The Lorentz force on the tether, F = B X I * L causes the tether to accelerate....
...Considering the geomagnetic field to be constant for sake of argument and also if the current is constant, the acceleration of the tether will be constant. The geomagnetic field strength does vary around the Earth but we will ignore that. The geomagnetic field strength also doesn't change when the observer is moving. And of course dM/dt = 0. How is this apparent paradox resolved?
Quote from: deltaMass on 07/08/2015 08:44 amQuote from: deltaMass on 07/07/2015 11:01 pmQuote from: deltaMass on 07/07/2015 09:36 pmI see that Shawyer's "latest paper" contains a specification of 2/3 N/W. This corresponds to a breakeven velocity of 3 m/s, mechanically an easily attainable value. Can we therefore expect Shawyer to branch out into the power generation field in the near future?Just a little follow-up here to answer a question that some may be asking: "What is a reasonable value of Newtons/Watt such that overunity could be achieved with a rotary device in a terrestrial lab?"It's a mechanical limitation. An aggressive spec. is something like 1,000 gee with a 1 metre radius arm. That's about 1,000 rpm and a tangential velocity of about 100 m/s. That in turn calls for a minimum k-value of 0.02 N/W.Keep that figure in mind.@kdhilliard has been kind enough to point out to me that the correct figure here should be 0.01 N/W, because the power breakeven velocity is what's important from a practical point of view. To recap:Energy breakeven velocity = 2/kPower breakeven velocity = 1/kThe power breakeven proof is not difficult:Pout = d/dt(0.5 m v2) = m v a = Pin when v := vpSo vp = Pin / (m a) = Pin / F = Pin / (k Pin) = 1/kQEDYour equation for Pout is wrong.Pout = d/dt(0.5 m v2) = m v a + 0.5 v2 dm/dtWhen you leave out dm/dt, it results in your over-unity paradox. In order to have acceleration, dm/dt cannot be zero. The kinetic energy gained can never exceed the change in mass, dm * c2.Todd
Quote from: deltaMass on 07/07/2015 11:01 pmQuote from: deltaMass on 07/07/2015 09:36 pmI see that Shawyer's "latest paper" contains a specification of 2/3 N/W. This corresponds to a breakeven velocity of 3 m/s, mechanically an easily attainable value. Can we therefore expect Shawyer to branch out into the power generation field in the near future?Just a little follow-up here to answer a question that some may be asking: "What is a reasonable value of Newtons/Watt such that overunity could be achieved with a rotary device in a terrestrial lab?"It's a mechanical limitation. An aggressive spec. is something like 1,000 gee with a 1 metre radius arm. That's about 1,000 rpm and a tangential velocity of about 100 m/s. That in turn calls for a minimum k-value of 0.02 N/W.Keep that figure in mind.@kdhilliard has been kind enough to point out to me that the correct figure here should be 0.01 N/W, because the power breakeven velocity is what's important from a practical point of view. To recap:Energy breakeven velocity = 2/kPower breakeven velocity = 1/kThe power breakeven proof is not difficult:Pout = d/dt(0.5 m v2) = m v a = Pin when v := vpSo vp = Pin / (m a) = Pin / F = Pin / (k Pin) = 1/kQED
Quote from: deltaMass on 07/07/2015 09:36 pmI see that Shawyer's "latest paper" contains a specification of 2/3 N/W. This corresponds to a breakeven velocity of 3 m/s, mechanically an easily attainable value. Can we therefore expect Shawyer to branch out into the power generation field in the near future?Just a little follow-up here to answer a question that some may be asking: "What is a reasonable value of Newtons/Watt such that overunity could be achieved with a rotary device in a terrestrial lab?"It's a mechanical limitation. An aggressive spec. is something like 1,000 gee with a 1 metre radius arm. That's about 1,000 rpm and a tangential velocity of about 100 m/s. That in turn calls for a minimum k-value of 0.02 N/W.Keep that figure in mind.
I see that Shawyer's "latest paper" contains a specification of 2/3 N/W. This corresponds to a breakeven velocity of 3 m/s, mechanically an easily attainable value. Can we therefore expect Shawyer to branch out into the power generation field in the near future?
For rfvp in response to Post #3648The generic DIY-er can easily and cheaply make or have made a frustum projected to resonate at 2.45 GHz. Can he/she design and build the circuitry necessary to phase lock it to an external reference or injection lock it to the frustum? Or mechanically lock the frustum to the magnetron? When hooked to the frustum, which of the many resonant frequencies does it lock to? How does the DIY-er know? If no thrust is detected with the first mode, how does he test the other resonant modes? If the magnetron is injection locked to the frustum how does the experimenter tune the magnetron outside the bandwidth of the thruster to determine if the thrust is related to resonance or an artifact of the test apparatus?----***I'm trying to secure the equipment needed to do just that. I wish I still had my business as I had fun toys like Spec Analysers and O-Scopes and Power Supplies and and and. Miss it.Controlling a 1000 w magnetron is not that hard, there are ways to make it a full wave 100% duty cycle and control the bandwidth and power out and even frequency lock it to the frustum cavity. What is the fly in the ointment is that thrusts have been measured with the magnetron unaltered and stuck onto the Frustum. I built a lot of flexibility into this first design and tried to stabilize the testing rig for repeatability. Simply it's hitting it with a rock first to see if it hollers, then get a set of micrometers to fine tune. To me it's like putting a firecracker into a can to see it fly when you should just tap it on the side, but it's data that needs to be gotten and I've said it before we need data. Not as much as CERN thank God.-----Put a tuning slug on the frustum. How does that affect the Q and mode(s) of resonance? How does the DIY-er know? When tuning, what is the feedback to the person doing the tuning, so that he knows what is going on? *** You insert a simple loop probe the cavity, monitor the frequencies. Simple stuff.-----Don’t get me wrong; I am VERY supportive of DIY-ers who have the initiative to try to ‘make it happen’; I am just pessimistic as to their chances of success using a free-running magnetron and not as sanguine as you about the triviality of ‘just tune the frustum and allow the magnetron to injection lock to it ‘ solutions to the known problems. I am aware that magnetrons HAVE been used, reportedly with success. I am also aware that one reason that the reported success of the magnetrons is greeted with so much skepticism is that with a magnetron it is difficult to know your test environment with precision. The good news is that if the magnetron is hooked to the frustum and unambiguous thrust appears and disappears in concert with the magnetron being turned on and off, victory can be declared, and we can turn the data over to the theorists to figure out why. Of course the theorists would probably like to know such details as which mode was being excited, the exact frequency that was responsible for the thrust, the Q at that mode, the power being injected within the bandwidth of the frustum and so on, but that could probably be determined post hoc. The bad news would occur if thrust DIDN’T occur. Especially if the frustum had a relatively high Q. Would the principle be falsified? Operating in the wrong mode? Spectral output of the magnetron places little or no energy into the bandwidth of the frustum? What next?-------****See my first comment on a raw magnetron radiation spewing malstrom into the cavity. If we really knew what was the best configuration and the theory was solid we wouldn't need to start off with a worse case. And it may be this is the key.It needs to be tested in this configuration... data we need more data. What happens if we control the frequency, power and the lock to give the best Q and poof it doesn't work? I built a lot of flexibility into this first frustum to start the step by step detailed analysis of power, frequencies, harmonics, different physical cavity lengths, antenna placements, dipole to helical to modified helical generating 1/4 wave backfires, waveguide insertion, dual slaved magnetrons into a wave guide locked to the cavity resonance, different end plate configurations small and large.I'm doing this test not to have fun as much as we need data, we need to know detailed step by step piece by piece analysis. Also and i posted this here before and it may be corny but i don't care.Because I choose to dream. I believe we are at a cusp of our growth on this ball of mud and if we don't evolve from this tiny seed called earth we may perish and never know the glorious heights that await us, or the true challenges of a universe that has no bounds. Yes, I dream, for humanity.-------As for SeeShells and the other builders: I don’t know where you are geographically or what access you have to microwave stuff in your ‘day job’, but if you are in the Northern VA/DC/Suburban MD area I MAY be able to get you access to such desirable widgets as a vector network analyzer, precision sig gens (including vector signal generators that in addition to the standard am/fm/cw allow you to generate signals with an arbitrary output spectrum), power meters, spectrum analyzers, and power amplifiers in the 100+ watt range. I am retired, but there is some possibility, considering the implications of real microwave thrusters, that my old employer would give me access, on a not to interfere basis, to any or all of the above. I haven’t asked. Yet.
Quote from: WarpTech on 07/08/2015 05:47 pm...Your equation for Pout is wrong.Pout = d/dt(0.5 m v2) = m v a + 0.5 v2 dm/dtWhen you leave out dm/dt, it results in your over-unity paradox. In order to have acceleration, dm/dt cannot be zero. The kinetic energy gained can never exceed the change in mass, dm * c2.ToddWhile I understand the physics I would like to offer an example that seems to violate this. An electrodynamic tether uses solar electrical power to energize a long cable that is normal to the geomagnetic field. DC power flows through the tether and then back through space with the help of charged particles. The Lorentz force on the tether, F = B X I * L causes the tether to accelerate. Considering the geomagnetic field to be constant for sake of argument and also if the current is constant, the acceleration of the tether will be constant. The geomagnetic field strength does vary around the Earth but we will ignore that. The geomagnetic field strength also doesn't change when the observer is moving. And of course dM/dt = 0. How is this apparent paradox resolved?
...Show me please where dm/dt figures in there...
...In other words, until a high Q frustum is tested with a stable, high power source whose frequency, power, and even output spectrum can be controlled at will, with wide enough frequency coverage to allow excitation at ALL resonant modes, it will not be possible, except for blind squirrel luck, to either confirm OR reject the existence of the generic EmDrive principle. ...
In response to SeeShells' Post #3877“It needs to be tested in this configuration... data we need more data. What happens if we control the frequency, power and the lock to give the best Q and poof it doesn't work? I built a lot of flexibility into this first frustum to start the step by step detailed analysis of power, frequencies, harmonics, different physical cavity lengths, antenna placements, dipole to helical to modified helical generating 1/4 wave backfires, waveguide insertion, dual slaved magnetrons into a wave guide locked to the cavity resonance, different end plate configurations small and large.”Sounds like a real, genuine engineer who knows what they are doing. Need a lab tech?Only semi-serious. Got home issues that would prevent me from leaving Northern VA for an extended period. If those could be resolved would be willing to follow directions and help any way I could. FWIW: I would be willing to work cheap. I. e. free.If my situation change before your testing is complete I'll let you know.
A Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.
In other words, until a high Q frustum is tested with a stable, high power source whose frequency, power, and even output spectrum can be controlled at will, with wide enough frequency coverage to allow excitation at ALL resonant modes, it will not be possible, except for blind squirrel luck, to either confirm OR reject the existence of the generic EmDrive principle.
Ok then, why no DIYer plan to use a klystron?
-I've been unable to find an old varian catalog to decode the part numbers.
Quote from: deltaMass on 07/08/2015 07:47 pm...Show me please where dm/dt figures in there...Ein = Pin * t = c2 * integral(dm/dt)*dtEout = 0.5 * (m + integral(dm/dt)*dt) * v2break even occurs when v = c, Ein = Eout(1/m(t))*integral(dm/dt)*dt = (1/2)(v/c)^2 * 1/(1 - (1/2)(v/c)^2) = 1 at v = c.Todd
Quote from: ElizabethGreene on 07/08/2015 10:00 pm-I've been unable to find an old varian catalog to decode the part numbers.Just found this: http://www.cpii.com/docs/related/37/VA936-VKC7936%20C-Band.pdfQuestion: What is exactly the "instantaneous 40 MHz bandwidth at –1dB points"?
For rfvp in response to Post #3648...The generic DIY-er can easily and cheaply make or have made a frustum projected to resonate at 2.45 GHz.
Can he/she design and build the circuitry necessary to phase lock it to an external reference or injection lock it to the frustum? Or mechanically lock the frustum to the magnetron? When hooked to the frustum, which of the many resonant frequencies does it lock to? How does the DIY-er know? If no thrust is detected with the first mode, how does he test the other resonant modes? If the magnetron is injection locked to the frustum how does the experimenter tune the magnetron out side the bandwidth of the thruster to determine if the thrust is related to resonance or an artifact of the test apparatus?
Put a tuning slug on the frustum. How does that affect the Q and mode(s) of resonance? How does the DIY-er know? When tuning, what is the feedback to the person doing the tuning, so that he knows what is going on?
I am just pessimistic as to their chances of success using a free-running magnetron and not as sanguine as you about the triviality of ‘just tune the frustum and allow the magnetron to injection lock to it ‘ solutions to the known problems.
The bad news would occur if thrust DIDN’T occur. Especially if the frustum had a relatively high Q. Would the principle be falsified? Operating in the wrong mode? Spectral output of the magnetron places little or no energy into the bandwidth of the frustum? What next?
(I’d use an external circulator just for fun though.).
a TWTA/solid state amp driven by a precision sig gen—where you KNOW what is going on--sound much more attractive to ME. YMMV.
As for SeeShells and the other builders: I don’t know where you are geographically or what access you have to microwave stuff in your ‘day job’, but if you are in the Northern VA/DC/Suburban MD area I MAY be able to get you access to such desirable widgets as a vector network analyzer, precision sig gens (including vector signal generators that in addition to the standard am/fm/cw allow you to generate signals with an arbitrary output spectrum), power meters, spectrum analyzers, and power amplifiers in the 100+ watt range. I am retired, but there is some possibility, considering the implications of real microwave thrusters, that my old employer would give me access, on a not to interfere basis, to any or all of the above. I haven’t asked. Yet.
Quote from: rfmwguy on 07/08/2015 03:39 pmA Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.This is correct. Magnetrons throw dirty RF.Building a Microwave Filter requires the same skills as building an EmDrive resonator. Is it worth filtering the magnetron output to get the output where you want it?You can clean up the magnetron output for cheaper than moving to solid state.In increasing order of cost/complexity:-Swap out your power supply for something more stable-Actively cool the magnetron-Filter and impedance match the output-Use a microcontroller to dynamically tune the magnetron.Tuning is the wrong word here. It's moving the peak of the magnetron output around by changing the magnetic field. Wrap some turns of wire around the magnet coils, measure the post-filter field strength with a micro-controller, and reduce or increase the current to the magnet bias coils with a feedback loop.This last bit is essentially what MasinaElectrica is doing, just with the micro-controller and filter feedback intelligence instead of manually moving the peak.I've looked for digestible resources on constructing traveling wave amplifiers to make solid state oscillators a realistic possibility. I have, to date, failed.
Quote from: flux_capacitor on 07/08/2015 10:07 pmQuote from: ElizabethGreene on 07/08/2015 10:00 pm-I've been unable to find an old varian catalog to decode the part numbers.Just found this: http://www.cpii.com/docs/related/37/VA936-VKC7936%20C-Band.pdfQuestion: What is exactly the "instantaneous 40 MHz bandwidth at –1dB points"?Believe this refers to 1db bandwidth of signal, meaning signal is broadband, 40 mhz wide unmodulated. What is missing here is spurious and harmonic specs. look for a spurious spec...
I am going with dirty power first. There are many combline bp filters, but at this stage, maybe its the chaos of em that makes it tick...too early to say for sure imho.