Talk-Polywell.org

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.

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.

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.

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....

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

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.

Carl White wrote: That doesn't sound promising.

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.

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