Quote from: aero on 10/22/2014 05:49 pmWhat you are saying is that these EM thruster devices need to be checked with a smoke trails, like air flow in a wind tunnel is highlighted. Hold a lighted punk stick next to it and turn the device on. Wouldn't their be some time delay between power on/off and thrust on and off?Have to think about what would a time constant involved in delay depend on. The electric effect is practically instantaneous. Momentum transfer has to do with hydrodynamics. There is no heat capacity and thermal difussivity involved like in a thermal effect. Time constant could depend on Reynolds number, hence viscosity, but viscosity of air is low. Also, speed of sound in air is 343 metres per second, which is pretty fast for these considerations.What is the time delay for the craft shown in this video? Seems to take off in an impulsive manner:
What you are saying is that these EM thruster devices need to be checked with a smoke trails, like air flow in a wind tunnel is highlighted. Hold a lighted punk stick next to it and turn the device on. Wouldn't their be some time delay between power on/off and thrust on and off?
Quote from: zen-in on 10/22/2014 06:52 pmQuote from: aero on 10/22/2014 06:19 pmThe time delay is not noticeable. I don't know if the time delay difference between this device and the EM thrusters could be detected. I don't think it can be with the data we have available to us.Actually the time delay is visible in these two plots of thrust data vs time. The first one is from Shawyer's 2008 paper. His 2013 and 2014 IAC papers don't have this kind of raw data. Both the up and down thrust roughly follow an exponential rise after power is applied and there is continued acceleration after the power is turned off.The second plot is from the JSC paper - Brady, White, et al. This also has a roughly exponential rise and continued thrust after RF power is turned off until the Cal pulse wipes it out.Both experiments have a thermal effect signature.Yes, some kind of a delay but not thermal for NASA Eagleworks. Around page 30 to 40 of this thread I calculated the thermal time delay based on the thermal diffusivity (thermal capacity and thermal conductivity) for the NASA Eagleworks experiments and ruled out the time delay and time decay as due to thermal effects because the Fourier time due to thermal effects is much longer than the ~2 second delay in the NASA Eagleworks experiments in the pulse rise from the baseline.The exponentially decaying rise after the initial 2 sec pulse may indeed be a thermal effect. Maybe related to their "baseline problem due to the magnetic damper interaction with the power cable..." Ionic wind time delay ?Paul March had also though about thermal effects and wrote about it. It is interesting that while these researchers can rule out thermal effects (based on standard heat transfer texts) the theory of ionic wind has not been written until recently. Perhaps nobody has computed or ruled out ionic wind, really...
Quote from: aero on 10/22/2014 06:19 pmThe time delay is not noticeable. I don't know if the time delay difference between this device and the EM thrusters could be detected. I don't think it can be with the data we have available to us.Actually the time delay is visible in these two plots of thrust data vs time. The first one is from Shawyer's 2008 paper. His 2013 and 2014 IAC papers don't have this kind of raw data. Both the up and down thrust roughly follow an exponential rise after power is applied and there is continued acceleration after the power is turned off.The second plot is from the JSC paper - Brady, White, et al. This also has a roughly exponential rise and continued thrust after RF power is turned off until the Cal pulse wipes it out.Both experiments have a thermal effect signature.
The time delay is not noticeable. I don't know if the time delay difference between this device and the EM thrusters could be detected. I don't think it can be with the data we have available to us.
Quote from: Star One on 10/20/2014 11:17 amHere is the PDF mentioned above.http://www.emdrive.com/iac2014presentation.pdfIs there a paper with more details to be published ?"4 independent organisations, in 3 different countries" : what organisations ? with what kind of balance ? Someone present at the conference to take notes and give some context ?
Here is the PDF mentioned above.http://www.emdrive.com/iac2014presentation.pdf
...I wish we would get a Cavendish-type measurement (as performed by Brito Marini and Galian to nullify the MET-type drive) at John Hopkins as soon as possible....
.....This is not correct. What they tested was an MLT type drive not a MET type drive.
Am I to understand this 'Ionic Wind' explanation means this device would not produce thrust in a vacuum - or in space?
Good question. There are several explanations that have been proposed for how these (ionic wind) "lifters" work. From the theoretical explanation and experiments conducted by Prof.Barrett at MIT the answer is no, they wouldn't work in a vacuum.
Still useful then as a general principle if they will operate in an atmosphere, question is to me in relation to space how much of an atmosphere do they need to operate.
How can it be postulated that Evanescent Waves by themselves can solve the closed-system, momentum-conservation problem?They can't by themselves using classical physics. One spaceship may transmit an evanescent field to move external small nanosatellites next to it (would not be an interesting form of propulsion, and the center of mass composed by the nanosatellites and the spacecraft system would not accelerate either). But it cannot move itself just by using Evanescent waves without any external field. A spaceship cannot propel itself by using Evanescent Waves any better than it can propel itself using Electromagnetic Fields. It is a closed system. A swimmer can swim in the ocean because the ocean water has its own inertia and resists acceleration. An astronaut cannot propel itself by waving her arms and legs in space. To enable propulsion one must have an open system: external dark matter, external fields: like the Earth's magnetic field, an external aether, even consideration of the external quantum vacuum, etc. But certainly not just Evanescent Fields by themselves that are self generated and only interacting in a closed system.To avoid this confusion one must rely on conservation principles: conservation of momentum, conservation of energy, and variational principles.
QuoteStill useful then as a general principle if they will operate in an atmosphere, question is to me in relation to space how much of an atmosphere do they need to operate.Hence the 'cheat' - have the area around the electrodes partly enclosed, and inject just enough gas into the area for the device to function. You'd have to replenish the gas fairly often, though.But if the 'EM Drive' is a variant of these 'ionic wind lifters' that can function in a vacuum, then things get interesting. Vacuum testing needed.
QuoteSo the complete total of all the photons in the cavity are giving their momentum up, and more, to thrust every second. How can that possible make sense. And even don't look at the energy. Unruh waves can't come close to making a big enough change in mass to cause lost mass to exceed the existing mass. (mi=m(1-L/4T)) For this to work, T would need to be equal to or less than L/4. There is one way of course but if I say "Tachyons," I'll likely be banned.Then don't say 'Tachyons.'I've has idle thoughts about a long shot possible resolution to this problem these past couple of days.Muletron posted a video a couple days ago giving sort of a capsule history of research into subatomic particles. The part that intrigued me was where the narrator put forth a chart showing a dozen plus subatomic particles discovered in the search for the Higgs boson. His attitude - which I'd seen before in print - was one of embarrassed dismissal. The attitude being these particles are a sort of unprofitable sideline, not worth detailed investigation. Yet I wonder...might not one or more varieties of these particles hold part of the solution to this drive? They are elementary 'building block' type critters - maybe certain rules don't fully apply to them? Maybe they're attracted to photons?
So the complete total of all the photons in the cavity are giving their momentum up, and more, to thrust every second. How can that possible make sense. And even don't look at the energy. Unruh waves can't come close to making a big enough change in mass to cause lost mass to exceed the existing mass. (mi=m(1-L/4T)) For this to work, T would need to be equal to or less than L/4. There is one way of course but if I say "Tachyons," I'll likely be banned.
I made a ... estimate of the Flight thruster dimensions operating at 385 GHz.w-small = 7.062943185 cmw-big = 11.02062266 cmheight = 7.114289902 cm
Quote from: aero's doppelganger on 10/22/2014 07:52 pmI ... estimate ... the Flight thruster dimensions ...w-small = 1"w-big = 2"height = 3"...I am dizzy with all the tests that Shawyer has conducted and with the different names he gives the tested device. ...
I ... estimate ... the Flight thruster dimensions ...w-small = 1"w-big = 2"height = 3"...
A much higher frequency might indicate flex in the arm itself.