EM Drive

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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ScottL
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Re: EM Drive

Postby ScottL » Thu Sep 08, 2016 10:22 pm

https://www.reddit.com/r/EmDrive/comments/51b1r8/nasas_eagleworks_em_drive_testing_searching_for/

My views align with the above reddit poster. These are the exact issues with the EM Drive and what is going on.

birchoff
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Re: EM Drive

Postby birchoff » Sat Sep 10, 2016 4:01 am

ScottL wrote:
birchoff wrote:Umm.. I think you are mistaken.

The very first conference paper that Eagle Works published was for their experiment using a Frustum similar to shawyers but it had a Dielectric insert in it. Whites entire theory for why the thing works is based on the need for that Die electric insert. They also included the results from testing the Cannae device and proposed that the reason the null configuration of the Cannae device failed (showed propulsion) was because it still had a dielectric in it. Now Paul March has discussed on NSF about the issues they have had with some bolts melting during their testing but at no time have they ever said they are moving away from using a Die electric insert in the small end of their frustum.

I have been following the discussion on emdrive fervently since that AIAA conference paper both here and on NSF (Since Thread 1). Before then I was merely familiar with what Roger Shawyer was proposing but figured it was experimental error. Now it is true that their follow up test run after the AIAA paper met with problems using non vac rated parts in hard vacuum. But they retooled and acquired vac rated versions and re ran the tests. So like I said before the EW research is different because they are assuming that a critical part of generating thrust is the die electric. IIRC, I believe it was Paul March on NSF who said they tried without a dielectric and got no thrust. So there is ample evidence on the NSF threads to prove that they are using a Die Electric as of the last time Paul graced that forum.



That's the difference between Cannae and Shawyer's designs, the insert, so I would say they followed a Cannae design, not Shawyers per se. I know Paul mentioned some arcing problems in those designs though, so I would take issue with relying on those results\designs. I can't say definitively if EW is still using inserts or not because Paul isn't saying much on NSF or elsewhere. The last post he had was "we still see a signal," but did not mention any specifics, so there is no point in speculating. I was under the impression by the time they rolled around to the vacuum test they had eliminated the inserts as a possible source and had switched to Shawyer's design, but getting an impression from posts is difficult at best.

Personally, I'm waiting on the paper as I think Shawyer is mistaken much like Yang was until she corrected her experiment. I suspect that once published, EW's paper will receive proper critique, but I can't say whether EW will follow through with corrections to their design (low funding after all.) My fear is that they decide to focus on something else after the paper, having served it's purpose to drum up some funding, and we're stuck in limbo.


The choice of putting a dielectric insert into the frustum was not inspired by cannae. According to a reading of the first AIAA conference paper. It is obvious that cannae didnt believe the dielectric could even be important for thrust. From everything publicly available. It looks like the decision to use a dielectric was all EW's. I suspect this came from the fact that they also did experiments on Paul's Mach Lorrentz Thruster design, and measured thrust. Paul has repeatedly stated that he belives it is likely that the Q-Thruster theory and Mach Effect Theory are two sides of the same coin.

As for speculation on whether or not they continued to use an insert. One was included as of the very last news report explaining the design they were testing. In addition Paul March has said that when they tested without the dielectric (Shawyers configuration) they measured no thrust. In addition the computational model they are using to try and predict thrust includes the dielectric in it. It may not be conclusive proof but I would say there is ample smoke. I owuld be very very surprised if they moved away from the dielectric insert. Primarily because the Modes they are reportedly exciting are not the same as Shawyer's. Which for me is the only explaination that could potentially explain why shawyer may be getting real thrust while EW doesnt.

Carl White
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Re: EM Drive

Postby Carl White » Mon Sep 12, 2016 4:42 am

zapkitty wrote:
Carl White wrote:
zapkitty wrote:... but the configuration inherent to Cannae drive design requires that almost all of that surface area to be facing other drives at close range rather than facing deep space.


Why can't they be spread out? More surface area perpendicular to the axis of motion + significant fraction of light speed = danger from dust particles?


Would work with a long enough spacecraft spine, but the drive faces are represented as just a few degrees off perpendicular to the spine axis (maybe 10 degrees?) so to significantly reduce the number of thermal photon bounces you'd have to add a LOT of spine mass... double it or more?

That's a lot of added mass for a low thrust drive.

At some point, and fairly quickly I think, it'd be more economical to add straight-up thermal control surfaces.


Here is how they explain it:

Cannae wrote:The 5 thrusting cavities are cooled by radiative cooling to deep space. The maximum design temperature of cavity operation is 75 K. The cavities and structural elements around the cavities are coated with a high emissivity black finish. At design power, the thruster cavities receive a combined 73 watts of phase-locked RF power. This power is almost entirely consumed as ohmic heating in the walls of the cavities. The cavities continually radiate this heat to deep space.

The radiating surface area of the thruster section of the probe is approximately 90 square meters. The radiative surface area needed to radiate 73 watts from a temperature of 75 K to 3 K (the effective temperature of deep space) is 40 square meters. When the cavities radiate more than 73 watts of thermal energy, the operating temperature of the cavities drops below 75 K, reducing the radiative power of the cooling mechanism. The system will reach a natural equilibrium temperature that radiates all ohmic heating from the cavitiy walls. This equilibrium temperature will be below the 75 K maximum design temperature. Operating temperatures below 75 K will improve the surface resistance characteristics of the YBCO and improve the power-to-thrust performance of the propulsion system.


So the question seems to be whether a smooth envelope tightly enclosing the stack of drives would have a surface area of at least 40 square meters.
Last edited by Carl White on Mon Sep 12, 2016 5:31 pm, edited 1 time in total.

Tom Ligon
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Re: EM Drive

Postby Tom Ligon » Mon Sep 12, 2016 3:40 pm

Here's your chance. These podcasts usually have a phone-in line, although I don't know if it will be up for this particular one. The Space Show will have Woodward on:

"5. Sunday, Sept. 18 2016: 12-1:30 PM PDT (3-4:30 PM EDT, 2-3:30 PM CDT): For today I will archive and play the taped interviews from AIAA Space 2016. This will include my visit to the Woodward lab with John Hunt regarding Dr. Woodward's work on the Mach Thrusters. The program will be available as soon as you see it."

The Space Show is now podcasting effective May 3, 2005. Subscribe your pod casters to http://www.gigadial.net/public/station/11253/rss.xml. For questions or additional information, send e- mail to Dr. David Livingston dmlivings@yahoo.com, drspace@thespaceshow.com, or thespaceshow@gmail.com.

Skipjack
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Re: EM Drive

Postby Skipjack » Mon Sep 12, 2016 6:03 pm

Woodward is developing a drive based on a different principle, though.

Tom Ligon
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Re: EM Drive

Postby Tom Ligon » Mon Sep 12, 2016 8:42 pm

I figured anyone following this thread would be at least casually interested.

hanelyp
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Re: EM Drive

Postby hanelyp » Wed Sep 14, 2016 2:38 am

Carl White wrote:Here is how they explain it:

Cannae wrote:The 5 thrusting cavities are cooled by radiative cooling to deep space. The maximum design temperature of cavity operation is 75 K. The cavities and structural elements around the cavities are coated with a high emissivity black finish. At design power, the thruster cavities receive a combined 73 watts of phase-locked RF power. This power is almost entirely consumed as ohmic heating in the walls of the cavities. The cavities continually radiate this heat to deep space....

Why that cold if not for a superconducting chamber, and if the chamber and conduit superconduct how is the RF heating them?
The daylight is uncomfortably bright for eyes so long in the dark.

pbelter
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Re: EM Drive

Postby pbelter » Mon Sep 19, 2016 5:21 pm

An interesting article about the EM workshop this week in Colorado.
Some participants:

http://www.ibtimes.co.uk/emdrive-contro ... ce-1582115

Dr Martin Tajmar, Professor and Chair for Space Systems at the Dresden University of Technology's Institute of Aerospace Engineering, renowned for his work in researching and debunking space propulsion systems

Two researchers from California State University Fullerton (Dr Jim Woodward, an adjunct professor of physics, and Dr Heidi Fearn, a professor of physics) will make an appearance to discuss their experiments on a "Mach Effect Drive"

Professor David Hyland, a professor of aerospace engineering at Texas A&M University, who will be exploring the "Experimental Dynamic Casimir Effect".

Nembo Buldrini, a research scientist at Fotec GmbH

Paul March & Dr Jose Rodal


Carl White
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Re: EM Drive

Postby Carl White » Mon Sep 19, 2016 8:33 pm

pbelter wrote:An interesting article about the EM workshop this week in Colorado.

http://www.ibtimes.co.uk/emdrive-contro ... ce-1582115


Author of the article wrote:However, March will soon be leaving Eagleworks, according to another post in the same thread by another user close to the Nasa researchers.


That doesn't sound promising. :|

Skipjack
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Re: EM Drive

Postby Skipjack » Mon Sep 19, 2016 9:13 pm

Carl White wrote:That doesn't sound promising. :|

From what I understand, he is retiring.

ladajo
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Re: EM Drive

Postby ladajo » Tue Sep 20, 2016 8:51 pm

lat time I talked with him, I kind of recall him saying that the current campaign was probably his last. Although, he had said that before a couple of times as well I think. Paul has been on the ride for a while; he has every right to be tired.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
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Skipjack
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Re: EM Drive

Postby Skipjack » Tue Sep 20, 2016 9:24 pm

ladajo wrote:lat time I talked with him, I kind of recall him saying that the current campaign was probably his last. Although, he had said that before a couple of times as well I think. Paul has been on the ride for a while; he has every right to be tired.

Indeed!

AcesHigh
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Re: EM Drive

Postby AcesHigh » Wed Sep 21, 2016 10:01 pm

anyone listened the SpaceShow Mach Effect interview cited by Tom Ligon above?

birchoff
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Re: EM Drive

Postby birchoff » Wed Sep 21, 2016 11:30 pm

pbelter wrote:An interesting article about the EM workshop this week in Colorado.
Some participants:

http://www.ibtimes.co.uk/emdrive-contro ... ce-1582115

Dr Martin Tajmar, Professor and Chair for Space Systems at the Dresden University of Technology's Institute of Aerospace Engineering, renowned for his work in researching and debunking space propulsion systems

Two researchers from California State University Fullerton (Dr Jim Woodward, an adjunct professor of physics, and Dr Heidi Fearn, a professor of physics) will make an appearance to discuss their experiments on a "Mach Effect Drive"

Professor David Hyland, a professor of aerospace engineering at Texas A&M University, who will be exploring the "Experimental Dynamic Casimir Effect".

Nembo Buldrini, a research scientist at Fotec GmbH

Paul March & Dr Jose Rodal



The SSI conference is not about the EM DRive. It is an Exotic Propulsion conference that will have experimental results for the EmDrive, MET and other possible exotic propulsion devices; along with potential theories explaining how they believe those devices work.

pbelter
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Re: EM Drive

Postby pbelter » Fri Sep 30, 2016 3:28 pm



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