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#1400 by Chrochne on 19 Apr, 2016 07:33
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Bit off topic, but..
One wonders if EmDrive will be able to fly like this new Flyboard from the Zapata Racing company
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Found second link. You can see liftoff as well.
Usual training day - https://www.facebook.com/181423698582027/videos/1063955080328880/
I want that now!
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#1401 by rfmwguy on 19 Apr, 2016 14:28
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While we're reflecting on hovercraft as a potential downrange application of emdrive technology, March 29, 2016 video of darpa's Aurora VTOL scale demonstrator using hybrid electric engines. Scale model weight 300+ lbs
http://nextbigfuture.com/2016/04/darpa-vertical-take-offlanding-x-plane.html -
#1402 by Rodal on 19 Apr, 2016 15:07
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Dr. Rodal, suffice it to say that Q thrusters are NOT in the EWL paper now in review? Only Em and Cannae drives? thnx , K Cauliflower shaped? LOL
If you are seeking public information on Q-thrusters that are not the EM Drive and that are not RF resonant cavity thrusters like the Cannae drive, please note:
1) one of the inventors of the MLT thruster, Paul March is associated with NASA's Eagleworks efforts (co-author of several papers, including the 2014 Brady et.al. report)
2) Prof. Woodward's experimental and theoretical work on thrusters is being continued by Prof. Heidi Fearn (see this for her latest publications: https://www.researchgate.net/profile/Heidi_Fearn )
3) concerning Serrano's thruster (built by Gravitec Inc. at the request of Boeing and DARPA tested by NASA in 2013), I just checked, and his company Gravitec efforts appear to still be in existence. Their public summary reads:Quote from: Serrano, President / CTO GravitecGravitec Inc is developing a “propellantless propulsion system” for in space vehicles, like satellites and beyond. Our breakthrough propulsion system does not work via classical physical principles.
While we cannot speak for the agencies and organizations that have tested and that are testing our technology in their laboratories, we can admit to the fact that our technology is being independently tested.
We don’t like secrecy but the controversial nature of the technology requires that we keep the identity of the interested parties and our clients very discrete. Gravitec is about results not theory. We are not afraid to prove ourselves and our technology.
To date no individual or entity has found a classical explanation for the root cause of the thrust being observed. Theories abound but none fit all the facts.
Patent :
World Intellectual Property Organization: http://www.google.com/patents/WO2000058623A2?cl=en
http://www.google.com/patents/WO2000058623A3?cl=en
US Patent (lapsed ? as per Google Patents) http://www.google.com/patents/US6492784?cl=en -
#1403 by rfmwguy on 19 Apr, 2016 18:26
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Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Edit clearer pic
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#1404 by SeeShells on 19 Apr, 2016 18:54
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Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Edit clearer pic
That actually looks very good Dave. Nice work.
Shell -
#1405 by Monomorphic on 19 Apr, 2016 20:03
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Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Did you stick with 1mm copper or go thinner? -
#1406 by Rodal on 19 Apr, 2016 20:25
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.../...
I don't know where I read this, but I believe it was in one of the thousands of posts.
True, EagleWorks melted the nylon screws holding in the dielectric. The reason was the threads on the nylon screws didn't bind well in the treads. With the small gaps left the threads the microwave actions around the threads heated up the nylon screw and melted it. They used Teflon tape to wrap the screws and make a more secure fit and eliminated the problem of melting.
ShellMy understanding was that the Nylon screws were holding (through) a PTFE disk, the thick slab of dielectric, not that any thin Teflon tape was involved in wrapping things.
I have the same understanding
Upon further review of this subject:
1) I have not found anything on my notes, or on the EM Drive threads (using Google Advanced Search) concerning NASA using Teflon tape to solve this Nylon screw "melting" problem.
Perhaps Shell's memory about Teflon is related to one or both of these things:
1A) One of the dielectric materials that NASA used, (besides the now standard HDPE dielectric) was PTFE, and as we know, DuPont's tradename for PTFE is Teflon. An event described as the Nylon screws "melting" occurred when they were holding a PTFE dielectric, as one can notice in the following photograph:
1B) NASA considered (or used ?) a center bolt made out of PTFE ("Teflon") (*), since the center bolt did not have an issue with "melting" because of its center position (recall that the issue with "melting" screws was mode-dependent and therefore location-dependent as the "melting" was due to induction-heating of the end plate, and not just thermal contact between the induction heated metal end plate but also dielectric heating due to any gap thereof), much lower tan delta than Nylon (PTFE "Teflon" tan δ =0.00028 @ 3 GHz vs. PA "Nylon" tan δ =0.0800 @ 1 MHz ), and higher melting temperature than Nylon (PTFE "Teflon" Tm = 620.3°F vs PA "Nylon" Tm= 428 °F)
1C) aero made MEEP computer runs showing the electromagnetic field being able to escape through thread gaps
2) Review of the material properties makes it clear that the problem with the PA "Nylon" screws was due entirely to its huge value of tan δ (tan δ =0.0800 @ 1 MHz, (tan δ > 0.1 @ 10 GHz see Krupka) which is known to be hundreds of times higher than the tan δ for HDPE or PTFE. Hence dielectric heating of Nylon is hundreds of times greater (for the same electromagnetic power) than for materials like HDPE or PTFE.
3) I'm sure that NASA must have solved the PA "Nylon" screw issue purely by addressing the huge value of tan δ, and substituting with a polymer screw of similar tan δ as the HDPE or PTFE dielectrics used by NASA.(*)
4) Also upon reviewing this subject it is obvious that the HDPE dielectric never melted in any of NASA's tests. Not only it was inspected after tests and found to have preserved its shape, but due to its very low tan δ, the HDPE dielectric experiences very low dielectric heating at these levels of power input used in EM Drive tests (as one can readily verify by runnig calculations, using COMSOL, FEKO or ANSYS FEA or BEM), the heating experienced by the dielectric HDPE being mainly due to any thermal contact it may have with the induction-heated metal end.
BOTTOM LINE: PA "Nylon" screw "melting" was due to Nylon's huge value of (imaginary permittivity/(real permittivity)) tan δ ~ 0.1000 at 2 GHz, hundreds of times higher than the tan δ for HDPE or PTFE . This huge value of tan δ for Nylon is related to Nylon's time-temperature dielectric transition (as shown in Krupka's dielectrometer measurements).
The Nylon screws were going through the metal end plate to hold the dielectric, and hence the Nylon screws were subjected to dielectric heating (even if there would not be any electromagnetic fields escaping through thread gaps).
_____________
(*) Looking at readily available (McMaster-Carr), relatively-inexpensive, polymer cap screws, it looks like Polypropylene cap screws would be a great choice as cap screws for this application to hold the HDPE dielectric, because of its higher modulus of elasticity than PTFE (three times greater, see https://en.wikipedia.org/wiki/Young%27s_modulus, 1.5–2 GPA for Polypropylene vs 0.5 GPA for PTFE) while also having a low value of tan δ (see the classic masterpiece by Krupka et.al: http://tinyurl.com/j899zq4and this nice chart http://tinyurl.com/z464crm for comparison of PP, PTFE and HDPE and PA)
(mod edit - tinyurl inserted to prevent page break on long urls) -
#1407 by SeeShells on 19 Apr, 2016 21:13
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http://forum.nasaspaceflight.com/index.php?topic=39772.msg1521122#msg1521122
Upon further review of this subject:
1) I have not found anything on my notes, or on the EM Drive threads (using Google Advanced Search) concerning NASA using Teflon tape to solve this Nylon screw "melting" problem.
Perhaps Shell's memory about Teflon is related to one or both of these things:
1A) One of the dielectric materials that NASA used, (besides the now standard HDPE dielectric) was PTFE, and as we know, DuPont's tradename for PTFE is Teflon. An event described as the Nylon screws "melting" occurred when they were holding a PTFE dielectric, as one can notice in the following photograph:
<end clip>
I have also dug through the archives and even pulled out my own notes (dated 8-8-15) where I have a short note on using Teflon tape to secure an tight seal between the bolts and dielectric. Maybe I thought it was a solution and wrote it down wrong thinking it would help to secure the bolts. In the post * from my notes referring to 2-15 it is talked about using tape. I just looked at it and reviewing it. It was scotch tape that was mentioned. On 2-15 I wasn't even a member here but have read all the 1000's of posts.
* https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335327#msg1335327
It was a slip up on my part and sorry if it caused any confusion.
Shell -
#1408 by Rodal on 19 Apr, 2016 21:15
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http://forum.nasaspaceflight.com/index.php?topic=39772.msg1521122#msg1521122
Upon further review of this subject:
1) I have not found anything on my notes, or on the EM Drive threads (using Google Advanced Search) concerning NASA using Teflon tape to solve this Nylon screw "melting" problem.
Perhaps Shell's memory about Teflon is related to one or both of these things:
1A) One of the dielectric materials that NASA used, (besides the now standard HDPE dielectric) was PTFE, and as we know, DuPont's tradename for PTFE is Teflon. An event described as the Nylon screws "melting" occurred when they were holding a PTFE dielectric, as one can notice in the following photograph:
<end clip>
I have also dug through the archives and even pulled out my own notes (dated 8-8-15) where I have a short note on using Teflon tape to secure an tight seal between the bolts and dielectric. Maybe I thought it was a solution and wrote it down wrong thinking it would help to secure the bolts. In the post * from my notes referring to 2-15 it is talked about using tape. I just looked at it and reviewing it. It was scotch tape that was mentioned. On 2-15 I wasn't even a member here but have read all the 1000's of posts.
* https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335327#msg1335327
It was a slip up on my part and sorry if it caused any confusion.
Shell
Thank you for checking
Anyway, I am sure that the problem is unique to Nylon's huge value of tan delta, and that Polypropylene cap screws would be a great choice as cap screws for this application to hold the HDPE dielectric -
#1409 by Oakey on 19 Apr, 2016 21:32
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With regard to DR Rodals continued explanation of glass transition and melting. A real life example is the glass transition of freeze dried products. At a products eutectic point a frozen liquid will allow its internal intra molecular structure to re- organise. Such that channels are possible within crystalline and glass like structure without 'melting'. It's extremely important in freeze drying you hit this point or you get 2 very different outcomes from desired-
1. Too little temp results in a crust on the freeze drying cake often resulting in 'blow off' from build up of pressure
2. Collapse of cake into a goo. - melting.( Dr Rodals 'puddle')
In both cases product is a solid as both ' Frozen'
Apologies at description I haven't worked on FD in twenty odd years.
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#1410 by SeeShells on 19 Apr, 2016 21:39
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http://forum.nasaspaceflight.com/index.php?topic=39772.msg1521122#msg1521122
Upon further review of this subject:
1) I have not found anything on my notes, or on the EM Drive threads (using Google Advanced Search) concerning NASA using Teflon tape to solve this Nylon screw "melting" problem.
Perhaps Shell's memory about Teflon is related to one or both of these things:
1A) One of the dielectric materials that NASA used, (besides the now standard HDPE dielectric) was PTFE, and as we know, DuPont's tradename for PTFE is Teflon. An event described as the Nylon screws "melting" occurred when they were holding a PTFE dielectric, as one can notice in the following photograph:
<end clip>
I have also dug through the archives and even pulled out my own notes (dated 8-8-15) where I have a short note on using Teflon tape to secure an tight seal between the bolts and dielectric. Maybe I thought it was a solution and wrote it down wrong thinking it would help to secure the bolts. In the post * from my notes referring to 2-15 it is talked about using tape. I just looked at it and reviewing it. It was scotch tape that was mentioned. On 2-15 I wasn't even a member here but have read all the 1000's of posts.
* https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335327#msg1335327
It was a slip up on my part and sorry if it caused any confusion.
Shell
Thank you for checking
Anyway, I am sure that the problem is unique to Nylon's huge value of tan delta, and that Polypropylene cap screws would be a great choice as cap screws for this application to hold the HDPE dielectric
There was no way could I let it go, the truth is out there you know.
Shell -
#1411 by rfmwguy on 19 Apr, 2016 23:43
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I kept the 1mm copper. Its about as thin as I would want to go considering the mass of the endplates.Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Did you stick with 1mm copper or go thinner? -
#1412 by Eusa on 20 Apr, 2016 07:03
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Considered spherical endplates with the same curvature center point?
I kept the 1mm copper. Its about as thin as I would want to go considering the mass of the endplates.Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Did you stick with 1mm copper or go thinner? -
#1413 by rfmwguy on 20 Apr, 2016 12:13
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Axial signal injection, higher costs and uncertainty of payoff kept me from this. I expect this to be my last emdrive build and hope whatever results occur will help others in the future.
Considered spherical endplates with the same curvature center point?
I kept the 1mm copper. Its about as thin as I would want to go considering the mass of the endplates.Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Did you stick with 1mm copper or go thinner? -
#1414 by Monomorphic on 20 Apr, 2016 12:54
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Considered spherical endplates with the same curvature center point?
Fabricating spherical end-plates with the same curvature center point would be very expensive or labor intensive. I've even considered this method:
Other methods i've seen proposed are Electroplating Copper...
...and Copper Casting.
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#1415 by SeeShells on 20 Apr, 2016 13:13
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May want to contact this company.Considered spherical endplates with the same curvature center point?
Fabricating spherical end-plates with the same curvature center point would be very expensive or labor intensive. I've even considered this method:
Other methods i've seen proposed are Electroplating Copper...
...and Copper Casting.
https://www.fabricorproducts.com/online-store/bobeches-dishes-spun.html
Shell -
#1416 by Monomorphic on 20 Apr, 2016 13:19
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May want to contact this company.
https://www.fabricorproducts.com/online-store/bobeches-dishes-spun.html
Shell
Forgot about spinning. That's another method i've seen talked about here. Have you seen an estimated price from them? -
#1417 by SeeShells on 20 Apr, 2016 13:28
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They publish some of the prices and they are not expensive. I have several quotes $60-200May want to contact this company.
https://www.fabricorproducts.com/online-store/bobeches-dishes-spun.html
Shell
Forgot about spinning. That's another method i've seen talked about here. Have you seen an estimated price from them?
https://www.fabricorproducts.com/online-store/conical-spun-shapes-tapers/results,11-10.html
https://www.fabricorproducts.com/online-store/hollow-balls-half-balls-spun/half-balls-spun/results,11-10.html
They do have a 60 dollar min order -
#1418 by Eusa on 20 Apr, 2016 13:29
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Gess why the nature haven't often formed large-scaled warping drives... Of course because using the air is much easier.
Axial signal injection, higher costs and uncertainty of payoff kept me from this. I expect this to be my last emdrive build and hope whatever results occur will help others in the future.
Considered spherical endplates with the same curvature center point?
I kept the 1mm copper. Its about as thin as I would want to go considering the mass of the endplates.Hand cut copper and basic edge finish. Now awaiting tooling. All major copper cuts all done...finally.
Did you stick with 1mm copper or go thinner? 
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#1419 by Rodal on 20 Apr, 2016 13:52
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...
Excellent and insightful point !
Gess why the nature haven't often formed large-scaled warping drives...
An Astrophysicist has also inquired as to the fact that if the EM Drive concept would be possible, it would probably occur in Nature, and hence be observable with astrophysical instruments, yet, as it is my understanding, that he remarked that astrophysical data shows no such phenomena whatsoever, compatible with the notion of the EM Drive or Q-thrusters.
The lack of astrophysical data compatible with the notion of the EM Drive is something important to be addressed, together with the EM Drive conundrums regarding conservation of energy and conservation of momentum.
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