Quote from: zen-in on 10/23/2014 09:43 pmQuote from: aero on 10/23/2014 07:56 pmDon't want to forget that thrust has been measured in the same axial direction relative to the thruster whether the thruster was pointed up, down, left or right. This speaks strongly against outside thermal drafts.It does not speak to thermal expansion of course.My theory on thermally generated thrust claims the cone section transmits heat energy to the surrounding air by conduction. The two ends do not have exposed Copper so the heat flow from each end would be much less. FR4 (high density fiberglass as used in PCBs) is a better insulator than Copper. The fact that March saw < 1 degree change in temperature would be expected because of the good heat transfer from the Copper cone section to the surrounding air. There is no mention of the surrounding air temperature so I am assuming this < 1 degree change refers to just the Copper section of the device. ...You must have meant "transmits heat energy to the surrounding air by conduction convection" because heat transfer by convection in fluids like air occurs much faster than by conduction. Air has very low thermal conductivity and very low thermal diffusivity, so heat does not get transferred in air by conduction, but by convection.But at NASA Eagleworks the measured forces were in the horizontal direction. Furthermore, the direction of the force was always oriented towards the large diameter base, even when they flipped the EM Drive to point 180 degrees in the opposite direction. Furthermore, in the up and down test performed by Shawyer, the direction of the force should not have flipped (as reported by Shawyer) when Shawyer flipped the test article upside down, as natural convection always works such that the warmer part is on the bottom, and the air circulates from the warmer bottom part to the cooler top part of the chamber.Further bad news for explaining the NASA Eagleworks response as natural convection from the warmer EM Drive is that the NASA Eagleworks test show a pulse response rapidly rising in 2 seconds which coincides with the inertial response of the inverted torsional pendulum, and is way too short a time compared with the Fourier dimensionless time based on the thermal diffusivity of the materials involved and the characteristic length. So the initial time-response cannot be explained in terms of thermal natural convection. The speed of heat transfer is restricted by the thermal diffusivity of the material.
Quote from: aero on 10/23/2014 07:56 pmDon't want to forget that thrust has been measured in the same axial direction relative to the thruster whether the thruster was pointed up, down, left or right. This speaks strongly against outside thermal drafts.It does not speak to thermal expansion of course.My theory on thermally generated thrust claims the cone section transmits heat energy to the surrounding air by conduction. The two ends do not have exposed Copper so the heat flow from each end would be much less. FR4 (high density fiberglass as used in PCBs) is a better insulator than Copper. The fact that March saw < 1 degree change in temperature would be expected because of the good heat transfer from the Copper cone section to the surrounding air. There is no mention of the surrounding air temperature so I am assuming this < 1 degree change refers to just the Copper section of the device. ...
Don't want to forget that thrust has been measured in the same axial direction relative to the thruster whether the thruster was pointed up, down, left or right. This speaks strongly against outside thermal drafts.It does not speak to thermal expansion of course.
.....I used the Crooke's radiometer as an example. The rotation of the paddles is not from convection.
Considering Crookes radiometer, eliminates both conduction and convection. Crooke's radiometer is contained in a partial vacuum. None of the tested devices (NASA Eagleworks, Shawyer of Chinese) to my knowledge were tested in a partial vacuum. To my knowledge Crooke's radiometer does not move under ambient pressure conditions.
...Reynolds found that if a porous plate is kept hotter on one side than the other, the interactions between gas molecules and the plates are such that gas will flow through from the cooler to the hotter side. The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.end quote
Thanks also to zen-in that provided the picture that motivated the discussion that motivated this insight.
Quote from: Rodal on 10/23/2014 08:15 pmThanks also to zen-in that provided the picture that motivated the discussion that motivated this insight.And thanks also to Jack, who built the house that... never mind.
Quote from: zen-in on 10/24/2014 12:34 am...Reynolds found that if a porous plate is kept hotter on one side than the other, the interactions between gas molecules and the plates are such that gas will flow through from the cooler to the hotter side. The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.end quoteThis is an interesting effect of another nature. << The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. >>How would this work for the EM Drive? Would we have to posit that the "porous" part is the gap between the flat bases and the surface of the cone?It is a fact that all the EM Drives that were tested had removable flat bases that were simply torqued into place, they were not welded or bonded without porosity, so certainly one has to admit that there is a gap through which gas molecules can move (at the circumferential gap of the bases instead of the edges of the blade of the radiometer).
...Crooke's radiometer theory from Wikipedia:On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.Applying this to the em-drive the large end would be the cold side and the cone section the hot side. Air moves from the cold side to the hot side and generates a tangential force. This force is in the same direction as the theorized em force. (opposite to what I was proposing earlier). I don't think this requires a partial pressure; just a very low friction bearing or torsion pendulum.Shawyer's up/down thrust plot is not symmetrical. The up plot has a faster rise time. I could speculate that this difference is due to convection. But I don't know enough about how these plots were done.
Quote from: zen-in on 10/24/2014 01:51 amQuote from: Rodal on 10/24/2014 12:46 amQuote from: zen-in on 10/24/2014 12:34 am...Reynolds found that if a porous plate is kept hotter on one side than the other, the interactions between gas molecules and the plates are such that gas will flow through from the cooler to the hotter side. The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.end quoteThis is an interesting effect of another nature. << The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. >>How would this work for the EM Drive? Would we have to posit that the "porous" part is the gap between the flat bases and the surface of the cone?It is a fact that all the EM Drives that were tested had removable flat bases that were simply torqued into place, they were not welded or bonded without porosity, so certainly one has to admit that there is a gap through which gas molecules can move (at the circumferential gap of the bases instead of the edges of the blade of the radiometer).Crooke's radiometer theory from Wikipedia:On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.Applying this to the em-drive the large end would be the cold side and the cone section the hot side. Air moves from the cold side to the hot side and generates a tangential force. This force is in the same direction as the theorized em force. (opposite to what I was proposing earlier). I don't think this requires a partial pressure; just a very low friction bearing or torsion pendulum.Shawyer's up/down thrust plot is not symmetrical. The up plot has a faster rise time. I could speculate that this difference is due to convection. But I don't know enough about how these plots were done.Mmmm. The person that wrote this on Wikipedia literally copied what Prof. John Baez had already explained in his blog several years ago:http://math.ucr.edu/home/baez/physics/General/LightMill/light-mill.htmlSince Prof. Baez has been one of the very outspoken critics of Dr. White's Quantum Vacuum Plasma explanation and the NASA Eagleworks tests, I find it interesting, that to my knowledge Prof. Baez has not advanced the Crook radiometer theory as an explanation for the NASA Eagleworks experiments. Maybe this is a question that can be posed to Prof. Baez himself since the explanation quoted from Wikipedia has been taken from Baez himself.
Quote from: Rodal on 10/24/2014 12:46 amQuote from: zen-in on 10/24/2014 12:34 am...Reynolds found that if a porous plate is kept hotter on one side than the other, the interactions between gas molecules and the plates are such that gas will flow through from the cooler to the hotter side. The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.end quoteThis is an interesting effect of another nature. << The vanes of a typical Crookes radiometer are not porous, but the space past their edges behaves like the pores in Reynolds's plate. On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. >>How would this work for the EM Drive? Would we have to posit that the "porous" part is the gap between the flat bases and the surface of the cone?It is a fact that all the EM Drives that were tested had removable flat bases that were simply torqued into place, they were not welded or bonded without porosity, so certainly one has to admit that there is a gap through which gas molecules can move (at the circumferential gap of the bases instead of the edges of the blade of the radiometer).Crooke's radiometer theory from Wikipedia:On average, the gas molecules move from the cold side toward the hot side whenever the pressure ratio is less than the square root of the (absolute) temperature ratio. The pressure difference causes the vane to move, cold (white) side forward due to the tangential force of the movement of the rarefied gas moving from the colder edge to the hotter edge.Applying this to the em-drive the large end would be the cold side and the cone section the hot side. Air moves from the cold side to the hot side and generates a tangential force. This force is in the same direction as the theorized em force. (opposite to what I was proposing earlier). I don't think this requires a partial pressure; just a very low friction bearing or torsion pendulum.Shawyer's up/down thrust plot is not symmetrical. The up plot has a faster rise time. I could speculate that this difference is due to convection. But I don't know enough about how these plots were done.
[...Prof. Baez's explanation is a lot easier to follow. The Wikipedia authors left a lot out. It turns out the paddles of a Crooke's radiometer do turn as if a force was pushing against the dark side of each paddle. This analogy does not match the results of the em-drive experiment.
......I'm reasonably confident that Lo is the RF drive wavelength. .......I think my code is right and the equations are copied fairly but the zero value of Lg2 ~0.052 m, is not close to what we measured and looks to be too small even if the cone tapers all the way to the front end of the cylinder. I am misunderstanding Shawyer's paper is what I think.
Quote from: aero on 10/24/2014 05:18 am......I'm reasonably confident that Lo is the RF drive wavelength. .......I think my code is right and the equations are copied fairly but the zero value of Lg2 ~0.052 m, is not close to what we measured and looks to be too small even if the cone tapers all the way to the front end of the cylinder. I am misunderstanding Shawyer's paper is what I think.....Shawyer's Lambdag is the RF drive wavelength instead of Shawyer's Lambda0 (Lo)....
We now suppose that the beam enters a vacuum-filled waveguide. The waveguide tapers from free-space propagation, with wavelength L0, to dimensions that give a waveguide wavelength of Lg and propagation velocity vg.
Quoting from the linked paper above:QuoteWe now suppose that the beam enters a vacuum-filled waveguide. The waveguide tapers from free-space propagation, with wavelength L0, to dimensions that give a waveguide wavelength of Lg and propagation velocity vg. This statement led me to think that L0 was the RF drive wavelength. Or maybe L0 is the diameter of the small end?
Lo =0.894 * (RF drive wavelength)
QuoteLo =0.894 * (RF drive wavelength)Ok. I'll try that.---------------------------------------Now, while reading the above linked paper in detail, I found some Flight Thruster dimensions.Base plate diameter = 265 mm,Height = 164 mm.If those dimensions are consistent with the photograph, then we should be able to extract the small end dimension.---------------------------------------I plugged in Rodel's value of Lo. It moved the zero crossing slightly, but to the left.
Now, while reading the above linked paper in detail, I found some Flight Thruster dimensions.Base plate diameter = 265 mm,Height = 164 mm.If those dimensions are consistent with the photograph, then we should be able to extract the small end dimension.