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#1680 by X_RaY on 12 Jan, 2017 16:43
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https://forum.nasaspaceflight.com/index.php?topic=41732.msg1626572#msg1626572
Can EmPro calculate Q?
Again, at the moment I don't believe in this Q values based on calculations with HOBF. I get freaky inconclusive results when using it.As you can see in the first two results the situation differs from calculation to calculate. The reason is slightly different mesh size and coupling factors.
Don't forget to include the spherical end-plate frustum with Q of 111,454. That is a pretty significant increase.
EDIT
This is the same frustum as used for the Q compare but using HOBF and fine mesh. Instead of natural possible QL~36000, i get 207000 loaded Q!
If yes can you check the results with EmPro?
FEKO SE calculation is above, EMPro (FEM Eigenresonance solver) below.
Dimensions are the same, material is copper in both cases. EMPro results should show Q0.
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#1681 by WarpTech on 12 Jan, 2017 17:00
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If the answer is that you have a communication from Shawyer saying that the Demonstrator had spherical ends, can you please post such an excerpt from Shawyer, as you had in the past posted other responses from Shawyer?
Thanks
Email received from Roger 8 Dec 2015:QuoteWe used shaped end plates with a magnetron source successfully in our Demonstrator Engine. The water cooled, 1.2kW magnetron locked on to the cavity frequency once it had warmed up.
I could be mistaken, but I vaguely remember Shawyer telling TT that the curvature of the small end plate was not that critical and a flat one could be used just as well. It was the spherical big end plate that was the most significant. So perhaps the flight thruster was this way to allow for adjustments? Shawyer's latest patent has a flat big end and a quasi-spherical small end, so he's gone in that direction himself, it would seem. -
#1682 by sanman on 12 Jan, 2017 17:06
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I could be mistaken, but I vaguely remember Shawyer telling TT that the curvature of the small end plate was not that critical and a flat one could be used just as well. It was the spherical big end plate that was the most significant. So perhaps the flight thruster was this way to allow for adjustments? Shawyer's latest patent has a flat big end and a quasi-spherical small end, so he's gone in that direction himself, it would seem.
Makes sense - if nothing (or hardly anything) is making it to the small-end plate, then why worry too much about its shape? The Big End is where it's all happening. BigEndians For The Win! -
#1683 by Rodal on 12 Jan, 2017 17:13
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I could be mistaken, but I vaguely remember Shawyer telling TT that the curvature of the small end plate was not that critical and a flat one could be used just as well. It was the spherical big end plate that was the most significant. So perhaps the flight thruster was this way to allow for adjustments? Shawyer's latest patent has a flat big end and a quasi-spherical small end, so he's gone in that direction himself, it would seem.
Makes sense - if nothing (or hardly anything) is making it to the small-end plate, then why worry too much about its shape? The Big End is where it's all happening. BigEndians For The Win!
If the small end does not matter that much, then why does Shawyer place so much emphasis on his "cut-off guideline" for the small end, particularly when it is well known that there is no sharp cut-off for an electromagnetically resonant cavity?
We cannot have it both ways. If the Shawyer cut-off guideline is so important, so is the small end. -
#1684 by PotomacNeuron on 12 Jan, 2017 17:22
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Dave,
I'm not building the KISS Thruster as it has spherical end plates that are probably beyond the capability of DIY builders.
At this point in time of the discussions with the fabricators, the spherical end plates will be formed using a male and female mold and the cone with the flanges spun. Then everything will be skim machined to +-100um tolerance and rough polished, then copper electropolished and oxidation protected.
I do wish I could build this at home but with a goal of 2mN with 8W Rf, the build quality, polish and Q needs to be at Ql of 50K or above.
Also understand the KISS Thruster is in competition with those that bought your NSF1701B thruster. See you / them in the market.
I, for one, do not agree with your choice. Why not use that good old flat end frustum, with 100W-200W amplifier? Does that setting enough to produce 2mN, according to your theory (recall your 8mN claim of your last build) ? That will at most add a few hundred $ to your original budget. Many, me included, will think that you use the difficulty of manufacturing as an excuse to delay the delivery. Indeed, you have postponed it from end of January 2017 to end of 2017.
You have not priced a 2.45 GHz, 100W, DC Powered amplifier. They are closer to $3000, not a "few hundred $". I was going to go that route, but it's out of my price range.
You can harvest one from a solid state microwave oven, or a solid state microwave lamp. I bought two broken lumix lamps with $40. But I finally abandoned my plan to test an Emdrive, because I am skeptic and my experiment showing no thrust will not mean anything. -
#1685 by sanman on 12 Jan, 2017 17:33
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If the small end does not matter that much, then why does Shawyer place so much emphasis on his "cut-off guideline" for the small end, particularly when it is well known that there is no sharp cut-off for an electromagnetically resonant cavity?
We cannot have it both ways. If the Shawyer cut-off guideline is so important, so is the small end.
Perhaps experimental measurement is the only way to resolve any debate, and to flush out any hidden/unpredicted effects.
It's feeling like that story "Journey to Center of the Earth", where the group are making their own way, while sometimes following the breadcrumbs of an elusive fellow who traveled the path before us.
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#1686 by WarpTech on 12 Jan, 2017 17:34
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I could be mistaken, but I vaguely remember Shawyer telling TT that the curvature of the small end plate was not that critical and a flat one could be used just as well. It was the spherical big end plate that was the most significant. So perhaps the flight thruster was this way to allow for adjustments? Shawyer's latest patent has a flat big end and a quasi-spherical small end, so he's gone in that direction himself, it would seem.
Makes sense - if nothing (or hardly anything) is making it to the small-end plate, then why worry too much about its shape? The Big End is where it's all happening. BigEndians For The Win!
If the small end does not matter that much, then why does Shawyer place so much emphasis on his "cut-off guideline" for the small end, particularly when it is well known that there is no sharp cut-off for an electromagnetically resonant cavity?
We cannot have it both ways. If the Shawyer cut-off guideline is so important, so is the small end.
I am leaning toward the idea I had 2 years ago, that (almost) all the data, except Shawyer's highest reported thrust, is well below that of a perfectly columnated photon rocket of power P*Q. So the small end plate cold be acting like a partially reflecting mirror, that gets less reflective and more transmissive as it heats up. So he wants the reflection on the small end plate. He doesn't want the wave cut-off at the sidewalls, where it's not as well columnated. Just a hunch I'm working on... -
#1687 by meberbs on 12 Jan, 2017 17:35
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From almost day 1 on this forum, I have tried to make it very clear that I have a commercial end game. Have also disclosed there are several commercial clients for the very high quality S band thrusters that have been manufactured. Unless my clients disclose and publish photos, those thruster images will not be released.
If you are selling a product there is no reason you can't take pictures of the product before you deliver it, and release those publicly. In fact, it is generally a good idea to do so. (it's called advertising)
Demonstrating that said product works in a public fashion is even better advertising.
And don't say that you have a contract with them that prevents it, it is not their intellectual property, so there is no reasonable reason for them to insist on those terms.
Last comment on this.
The KISS Thruster photos and video will be released.
The 4 x high quality S band thrusters were produced under a commercial contract. Release of any more info is up to the clients.
You should consider that the so far released KISS Thruster data is well in advance of any other EmDrive Thruster detailed design release. Might consider there was considerable experience behind the design decisions. If you doubt that, please show the released thruster data from another DIYer that supports such a high specific force design?
As I stated, there is no reason that the clients would have control over your IP and you would be unable to release any information. (The identity of the clients, or how much they paid would make sense, but not the design or pictures of the thrusters)
How is your KISS data more advanced than any of the other builders? The available evidence from other experimenters makes it unlikely you will produce the thrust that you claim, and you have not released nearly as much details of your setup. The data that you have released is very questionable. Since there isn't data supporting you as having a "high specific force design," your last request is unreasonable. Plus the lack of it is why there is still doubt that the emDrive works at all. -
#1688 by WarpTech on 12 Jan, 2017 17:38
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You have not priced a 2.45 GHz, 100W, DC Powered amplifier. They are closer to $3000, not a "few hundred $". I was going to go that route, but it's out of my price range.
You can harvest one from a solid state microwave oven, or a solid state microwave lamp. I bought two broken lumix lamps with $40. But I finally abandoned my plan to test an Emdrive, because I am skeptic and my experiment showing no thrust will not mean anything.
Tunable? Show me please. I've looked for amplifiers where I could vary the input frequency within the range required. I didn't see anything that could do that, at 100W, that was less than $1600! It can't be a fixed frequency like a Magnetron. That adds a great deal of complexity and issues that have nothing to do with the EmDrive to be tested. -
#1689 by PotomacNeuron on 12 Jan, 2017 18:16
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You have not priced a 2.45 GHz, 100W, DC Powered amplifier. They are closer to $3000, not a "few hundred $". I was going to go that route, but it's out of my price range.
You can harvest one from a solid state microwave oven, or a solid state microwave lamp. I bought two broken lumix lamps with $40. But I finally abandoned my plan to test an Emdrive, because I am skeptic and my experiment showing no thrust will not mean anything.
Tunable? Show me please. I've looked for amplifiers where I could vary the input frequency within the range required. I didn't see anything that could do that, at 100W, that was less than $1600! It can't be a fixed frequency like a Magnetron. That adds a great deal of complexity and issues that have nothing to do with the EmDrive to be tested.
You tune the OSC, not the amplifier. The amplifiers should be expected to work for a certain range. For the 915 MHz luxim LIFI lamp, I expect the amplifier to work at least from 900-930 MHz. -
#1690 by flux_capacitor on 12 Jan, 2017 19:18
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Dave,
I'm not building the KISS Thruster as it has spherical end plates that are probably beyond the capability of DIY builders.
At this point in time of the discussions with the fabricators, the spherical end plates will be formed using a male and female mold and the cone with the flanges spun. Then everything will be skim machined to +-100um tolerance and rough polished, then copper electropolished and oxidation protected.
I do wish I could build this at home but with a goal of 2mN with 8W Rf, the build quality, polish and Q needs to be at Ql of 50K or above.
Also understand the KISS Thruster is in competition with those that bought your NSF1701B thruster. See you / them in the market.
I, for one, do not agree with your choice. Why not use that good old flat end frustum, with 100W-200W amplifier? Does that setting enough to produce 2mN, according to your theory (recall your 8mN claim of your last build) ? That will at most add a few hundred $ to your original budget. Many, me included, will think that you use the difficulty of manufacturing as an excuse to delay the delivery. Indeed, you have postponed it from end of January 2017 to end of 2017.
You have not priced a 2.45 GHz, 100W, DC Powered amplifier. They are closer to $3000, not a "few hundred $". I was going to go that route, but it's out of my price range.
Todd, have you looked into the Chinese power amps sold by Yonlit? TheTraveller said he picked a 100W amp for US$450 and later a 250W model:
100W GSM CDMA DCS Power Amplifier on Alibaba
Product page on yonlit.com
• Max output power 50dBm (100W)
• Input/Output VSWR ≤ 1.5
• Working Voltage 12-13.8VDC or 28VDC depending on the model
• Working Current 8A
• Dimensions 200×150×25 mm or 210×110×25 mm
• Frequency range :
VHF: 137-174MHz
UHF: 380-470MHz
EGSM: 925-960MHz
CDMA: 851-894MHz
DCS: 1805-1880MHz
3G: 2110-2170MHz
Wi-Fi: 2400-2500MHz
4G/LTE2600: 2500-2600MHz
4G/LTE2700: 2600-2700MHz
or Customized
The frequency is adjustable over the specified range set in requirements when ordering.
Yonlit also sells a smaller and cheaper 44.5dBm (25-28W) model (180×91×22 mm) that would be perfect for the KISS thruster
http://www.yonlit.com/ShowProducts.asp?Page=1&ID=26
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#1691 by WarpTech on 12 Jan, 2017 19:24
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Todd, have you looked into the Chinese power amps sold by Yonlit? TheTraveller said he picked a 100W amp for US$450 and later a 250W model:
100W GSM CDMA DCS Power Amplifier on Alibaba
Product page on yonlit.com
• Max output power 50dBm (100W)
• Input/Output VSWR ≤ 1.5
• Working Voltage 12-13.8VDC or 28VDC depending on the model
• Working Current 8A
• Dimensions 200×150×25 mm or 210×110×25 mm
• Frequency range :
VHF: 137-174MHz
UHF: 380-470MHz
EGSM: 925-960MHz
CDMA: 851-894MHz
DCS: 1805-1880MHz
3G: 2110-2170MHz
Wi-Fi: 2400-2500MHz
4G/LTE2600: 2500-2600MHz
4G/LTE2700: 2600-2700MHz
or Customized
The frequency is adjustable over the specified range set in requirements when ordering.
Yonlit also sells a smaller and cheaper 44.5dBm (25-28W) model (180×91×22 mm) that would be perfect for the KISS thruster
http://www.yonlit.com/ShowProducts.asp?Page=1&ID=26
Is this the same Amp TT had that died after a few minutes of operation, and they "lost" the replacement in the mail? If so, it doesn't sound like a good investment to me. -
#1692 by flux_capacitor on 12 Jan, 2017 19:42
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Is this the same Amp TT had that died after a few minutes of operation, and they "lost" the replacement in the mail? If so, it doesn't sound like a good investment to me.
Mmmh… I understand why you are reluctant to buy one. To be more precise, TT specifically said:The Rf amp didn't burn out. The variable attenuator failed to deliver an output signal.
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#1693 by Peter Lauwer on 12 Jan, 2017 20:07
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The German company Kuhne makes amps which are not too expensive. And have interesting specs, broadband for instance (2.0-2.7 GHz, for example, ideal for me).
The 4 W is reduced in price, €399 incl. VAT
https://www.kuhne-electronic.de/kuhne/en/shop/industrial/prof-power-amplifier/KU+PA+2002704A++GaAsFET+Power+Amplifier/?card=443
The 8 W, is about twice as expensive.
http://shop.kuhne-electronic.de/kuhne/en/shop/industrial/prof-converter/prof-up-converter/KU+PA+2002708+A++GaAs+FET+Power+Amplifier/?card=444#_tab_content1 -
#1694 by Peter Lauwer on 12 Jan, 2017 20:14
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... But I finally abandoned my plan to test an Emdrive, because I am skeptic and my experiment showing no thrust will not mean anything.
You are probably not totally skeptic, since you spend your time visiting and replying on this forum.
Would you call me a skeptic, if I put my believe at 10%? Will my experiment only mean something when I do measure an anomalous force?
Never mind, I mainly do this experiment to get an answer for myself. And for the fun of it. I'll decide what to do next when I either find a clear effect or clearly not. -
#1695 by rfmwguy on 12 Jan, 2017 20:51
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Don't mess with expensive mil amps. 200W Microwave source, batteries included:
https://www.cnet.com/products/wayv-adventurer/preview/ -
#1696 by WarpTech on 12 Jan, 2017 20:51
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The German company Kuhne makes amps which are not too expensive. And have interesting specs, broadband for instance (2.0-2.7 GHz, for example, ideal for me).
The 4 W is reduced in price, €399 incl. VAT
https://www.kuhne-electronic.de/kuhne/en/shop/industrial/prof-power-amplifier/KU+PA+2002704A++GaAsFET+Power+Amplifier/?card=443
The 8 W, is about twice as expensive.
http://shop.kuhne-electronic.de/kuhne/en/shop/industrial/prof-converter/prof-up-converter/KU+PA+2002708+A++GaAs+FET+Power+Amplifier/?card=444#_tab_content1
20% efficiency? This sucker burns 40 watts to give you 8! That's awful. -
#1697 by WarpTech on 12 Jan, 2017 21:30
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KISS Thruster update:
Simulation looks good.
Ql 71.5k,
Impedance 49.9 ohms,
VSWR 1.13:1,
TE013 resonance 2.4449GHz
Time to make it real.
How much does the Q change if just the small end plate is flat? Just curious. It would save some time in manufacturing if it doesn't make a huge difference. -
#1698 by Monomorphic on 12 Jan, 2017 22:23
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Don't mess with expensive mil amps. 200W Microwave source, batteries included:
https://www.cnet.com/products/wayv-adventurer/preview/
I would pick one up tomorrow if they were available. Freescale NXP never replied to my inquiries about the MHT31250C RF Cooking Module. I sent them another email today.
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#1699 by Rodal on 12 Jan, 2017 22:29
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KISS Thruster update:
Simulation looks good.
Ql 71.5k,
Impedance 49.9 ohms,
VSWR 1.13:1,
TE013 resonance 2.4449GHz
Time to make it real.
How much does the Q change if just the small end plate is flat? Just curious. It would save some time in manufacturing if it doesn't make a huge difference.
According to the calculations by everybody here, using exact solutions, Finite Element and Boundary Element methods, the Quality factor of resonance (Q) does not change appreciable for either the big end or the small ends being flat or spherical !
Neither of them makes much difference to the quality factor.
This follows trivially from the fact that the geometries being explored by Shawyer (experimental, demonstrator, flight thruster), NASA, and others in their experiments have been close to cylindrical and have only departed marginally from a cylindrical geometry.
This follows trivially from the fact that the cone angles being used in these experiments so far are small.
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The difference in Q due to spherical ends instead of flat ends is of the same order as small changes in geometry or in the conductiivty of the materials involved.
You are not going to get an order of magnitude improvement in Q by simply using spherical ends instead of flat ends for these geometries explored so far. For a high Q, it is much more important to concentrate on the excitation, coupling, mode shape, material conductivity, surface finish and tolerances.
The lowest Q ever reported EM Drive experiment was obtained with both end spherical, Q<50 according to Martin Tajmar
What further proof than Tajmar's experiment that spherical ends are no panacea ?
People using flat ends have reported Q's in the thousands and tens of thousands, compared with Tajmar spherical ends Q<50 which was designed according to Tajmar under Shawyer's advice.
