Well, Edison was one of the greatest inventors. He was completely self-taught (with visits to the Cooper Union). Edison was born only 16 years after Maxwell. Edison was responsible for some of the greatest electromagnetic inventions ever, yet he was not a theoretical physicist like Maxwell or Hertz. Who was the inventor? Edison or Maxwell?. Why should Shawyer be the one expected to explain the physics of why it works (if it does work)?
QuoteWell, Edison was one of the greatest inventors. He was completely self-taught (with visits to the Cooper Union). Edison was born only 16 years after Maxwell. Edison was responsible for some of the greatest electromagnetic inventions ever, yet he was not a theoretical physicist like Maxwell or Hertz. Who was the inventor? Edison or Maxwell?. Why should Shawyer be the one expected to explain the physics of why it works (if it does work)?People here and elsewhere say a coherent theory is needed in order to advance with this project....
Quote from: JPLeRouzic on 02/27/2015 09:48 amQuote from: aero on 02/27/2015 04:37 amIt's to bad that we can't find a way that one of the little known or unknown solutions to Maxwell's equations can cause a momentum. There is obviously momentum in electromagnetic waves. There are also some little known electromagnetic effects that create torque. http://arxiv.org/abs/0807.1310
Quote from: aero on 02/27/2015 04:37 amIt's to bad that we can't find a way that one of the little known or unknown solutions to Maxwell's equations can cause a momentum. There is obviously momentum in electromagnetic waves. There are also some little known electromagnetic effects that create torque.
It's to bad that we can't find a way that one of the little known or unknown solutions to Maxwell's equations can cause a momentum.
Quoting @AeroQuoteUnless of course it is surface electrons excited by the high power resonant RF, tunnelling through the 35 micron copper ends.Quoting @JPLeRouzicQuoteYes, and many other things may happen were not tested nor even proposed. I wonder how people can know that a lot of energy is pumped in this device and imagine nothing will get out. At the very least thermal effects should happen. Testing it in (near) vacuum doesn't eliminate the thermal hypothesis. Even Pioneer's acceleration that was due to thermal effects after all: http://spectrum.ieee.org/aerospace/astrophysics/finding-the-source-of-the-pioneer-anomalyAnother thing that strikes me is that people search for a unique cause explaining everything, which is a bit unlikely.One last thought: If a simulator shows results, build this device and publish results in a mainstream conference. Interesting things may happen ;-)There are absolutely thermal effects. For every watt pumped in, you get that much heat out as IR. An RF dummy load is an efficient converter of RF to heat. The systemic effects slide with the dummy load attached is the control for heat. Thermal artifacts were a major area of exploration in both threads. Paul March provided lots of data to show that thermal effects were extensively studied over at Eagleworks. There's a thermal analysis on this thread, one of many indications that heat was controlled for: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326997#msg1326997 Plus the math that has been done numerous times for a photon rocket doesn't add up. So the vacuum did eliminate the thermal hypothesis.
Unless of course it is surface electrons excited by the high power resonant RF, tunnelling through the 35 micron copper ends.
Yes, and many other things may happen were not tested nor even proposed. I wonder how people can know that a lot of energy is pumped in this device and imagine nothing will get out. At the very least thermal effects should happen. Testing it in (near) vacuum doesn't eliminate the thermal hypothesis. Even Pioneer's acceleration that was due to thermal effects after all: http://spectrum.ieee.org/aerospace/astrophysics/finding-the-source-of-the-pioneer-anomalyAnother thing that strikes me is that people search for a unique cause explaining everything, which is a bit unlikely.One last thought: If a simulator shows results, build this device and publish results in a mainstream conference. Interesting things may happen ;-)
Great find and thanks for bringing it to our attention, this is the first time I see this patent.Very thought provoking, and interesting in its own right.I note that Shawyer's patent was file in 1988 !, that's 27 years ago !This man has been working at this for a long, long time
An electronic propulsion engine that creates a propulsive force or thrust using forces or electrostatic electromagnetic forces, with an effect that is similar to the thrust of a jet or rocket engine. Forces are generated using electromagnets or capacitor plates that are separated by dielectric spacer cores and are operated with two modulated currents. The two modulated currents are synchronized, but with a relative phase such that the forces on the two magnets or capacitor plates are not balanced. Included are techniques to reduce circuit impedance and control field dispersion, such as tuned LCR circuits, dielectric core materials between the magnets or capacitor plates, and RF superconductors result in high propulsion efficiencies. The system operates at RF frequencies and can also be used as a communication device.
Hi. Newcomer here but I have been following since thread 1....
...To my knowledge Roger Shawyer filed 4 patent applications related to the EmDrive, here they are attached at the bottom of this message....
Quote from: Mulletron on 02/27/2015 08:24 pmSo the vacuum did eliminate the thermal hypothesis....5*10-6 Torr is hardly a vacuum good enough to eliminate the thermal hypothesis. That's what you encounter at 1000 km high or so.Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects.
So the vacuum did eliminate the thermal hypothesis.
http://www.ebay.com/itm/AERCOM-Microwave-RF-Isolator-Circulator-2-4GHz-20dB-isolation-Low-I-L-TESTED-/281549538390?ssPageName=ADME:L:OU:US:1120Picked up one of these puppies on Ebay to protect my amp. Another example of broken time reversal symmetry in action.Got about an oz of very expensive liquid metal from here:http://www.amazon.com/Gallium-Indium-Eutectic-GaInSn-68-5%25/dp/B00KN92MWW/ref=sr_1_3?ie=UTF8&qid=1425074693&sr=8-3&keywords=galinstanSo back to the copper from way back: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326742#msg1326742...Been working with the supplier with a machine shop I posted about way back:http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326669#msg1326669 I'm going that route. The quote I got is: price: $120.00 layout + $51.63 for part + freight. So I have to pay the layout, then anyone else who wants one of these: but built in 16oz copper, with a smooth butt seam inside, and 1/4" flange around edges, can get one for about 50 bucks plus shipping. If all this works out, it'll fulfill my goal of making a replication by DIYers easier. For me, paying the layout plus price about breaks even with buying the sheet myself and fumblefuddeling around trying to solder up a cone at home. So I'm happy. I'll get back with more later, when the items are at home.
How do you intend to measure the (very tiny) thrust ? Reading back NASA's paper, it seems they had to run the experiment in a lab with complex (and expensive) tools to remove all parasite effects that would interfere with the thrust from the apparatus. Maybe you have access to such equipment ?
Quote from: MathieuA on 02/28/2015 06:30 pmHow do you intend to measure the (very tiny) thrust ? Reading back NASA's paper, it seems they had to run the experiment in a lab with complex (and expensive) tools to remove all parasite effects that would interfere with the thrust from the apparatus. Maybe you have access to such equipment ?- Roger Shawyer achieved 174 mN of thrust at an input power of 450 W in 2010 (he then operated its engine up to 600 W but thrust levels are not known fort that power).- Chinese NWPU achieved 720 mN @ 2500 W in 2010.- Eagleworks achieved 116 µN @ 17 W in 2014.So if you're gonna try an EmDrive at home, you'd better feed it with at least severals hundred of watts of electric power to be able to measure tens to hundreds of millinewtons. Staying below 100 W seems to produce thrusts in the micronewton range, way too low and something only a dedicated lab like Eagleworks can detect with expensive apparatus. At that level you detect any low-frequency vibrations like small seismic events. Indeed you noticed in the paper that Eagleworks used an isolated test rig from the Apollo program era with an extremely sensitive torsion pendulum, and on windy days they were able to detect the waves from the Gulf of Mexico, about 25 miles southeast of JSC… This low-power experiment was intended for a specific purpose: test the EmDrive in a hard vacuum. Only a small device with a compact and light onboard power amplifier could be tested, hence the very low power used compared to previous experiments by Shawyer and the Chinese. The Chinese pursue a different path: they try to brutally produce the maximum thrust available with cheap but high power magnetrons. This way they cannot eliminate convection current or test their drive in a hard vacuum, but they can show the thrust achieved is too high to be accounted only for trivial reasons. Besides they showed the engine could compete with modern ion thrusters and perhaps one day overtake them.You can also let the test article rotate. But it's not easy. Shawyer conducted such dynamic tests on a rotating rig. The whole device weighted 100 kg, comprising the thruster and a cooling system mounted on a beam, supported on a low-friction air bearing. The device reportedly consumed 300 W of power and produced a force of 96.1 mN, a maximum speed of 2 cm/s over 185 cm during testing in October 2006. See this 2007 article by Eureka magazine who covered the story, and this article from Wired the year after, which displays a video where you can see the mammoth.Interesting thing to note: Shawyer claims the engine starts to accelerate only when the magnetron frequency locks to the resonant frequency of the thruster, following an initial warm up period where it does not move; thus according to him eliminating possible spurious forces.We'd need some data of tests made with high-Q superconducting cavities. But only Cannae LCC briefly talked about such test results before shutting down their web site.
....Interesting thing to note: Shawyer claims the engine starts to accelerate only when the magnetron frequency locks to the resonant frequency of the thruster, following an initial warm up period where it does not move; thus according to him eliminating possible spurious forces.....
Quote from: JPLeRouzic on 02/28/2015 12:51 pmQuote from: Mulletron on 02/27/2015 08:24 pmSo the vacuum did eliminate the thermal hypothesis....5*10-6 Torr is hardly a vacuum good enough to eliminate the thermal hypothesis. That's what you encounter at 1000 km high or so.Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects.@Mulletron must have meant "So the vacuum did eliminate the [natural convection] thermal hypothesis" . He wrote "thermal hypothesis" without the words "natural convection" because he thought that it was obviously understood he was referring to convection in the context he was discussing: what is the difference between ambient pressure and 5*10-6 Torr. Obviously this pressure makes a huge difference for natural convection currents, as a trivial calculation can show that 5*10-6 Torr vacuum does eliminate the natural convection hypothesis that was advanced in most media (including Prof. Baez's blog) as the most likely explanation for the measurements. @Frobnicat, was proposing the thermal convection hypothesis as a possible artifact, and he worked some equations in Thread 1. I do not recall @Frobnicat objecting to a 5*10-6 Torr vacuum nullifying the hypothesis of natural thermal convection from the EM Drive being able to produce the measured forces. Concerning <<Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects>>, yes the Pioneer anomaly was successfully explained by a team of JPL engineers/scientists on the basis of thermal radiation effects (not natural convection thermal effects). Thermal radiation, an entirely different (from convection) means of thermal transport, will take place even in a perfect vacuum, as thermal radiation is electromagnetic radiation and therefore does not need a gas or a fluid as a transport medium. On the other hand natural convection is completely dependent on fluid or gas medium to carry it, and without a fluid or a gas, there cannot be any thermal convection. Thermal convection involves fluid advection.Radiative heat transfer is the only form of heat transfer that can take place in a vacuum. Radiative heat transfer depends on the difference between the fourth power of the temperatures between the radiating surface and the irradiated surface, the surface areas and the emissivities of the radiating and irradiated surfaces and the Stefan–Boltzmann constant . It may be important for the Pioneer anomaly: an extremely small effect comprising an acceration towards the Sun, of only 8.74×10^(−10) m/s^2, due to asymmetrical radiation of heat from the Radioisotope thermoelectric generators or from the spacecraft electronics reflecting from the back of the spacecraft's dish-like main antenna, causing a recoil like sunlight striking a solar sail.But in the case of the EM Drive, how much does the temperature difference between radiated and irradiated surfaces have to be to to justify the measured thrust forces ?
Quote from: Rodal on 02/28/2015 03:21 pmQuote from: JPLeRouzic on 02/28/2015 12:51 pmQuote from: Mulletron on 02/27/2015 08:24 pmSo the vacuum did eliminate the thermal hypothesis....5*10-6 Torr is hardly a vacuum good enough to eliminate the thermal hypothesis. That's what you encounter at 1000 km high or so.Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects.@Mulletron must have meant "So the vacuum did eliminate the [natural convection] thermal hypothesis" . He wrote "thermal hypothesis" without the words "natural convection" because he thought that it was obviously understood he was referring to convection in the context he was discussing: what is the difference between ambient pressure and 5*10-6 Torr. Obviously this pressure makes a huge difference for natural convection currents, as a trivial calculation can show that 5*10-6 Torr vacuum does eliminate the natural convection hypothesis that was advanced in most media (including Prof. Baez's blog) as the most likely explanation for the measurements. @Frobnicat, was proposing the thermal convection hypothesis as a possible artifact, and he worked some equations in Thread 1. I do not recall @Frobnicat objecting to a 5*10-6 Torr vacuum nullifying the hypothesis of natural thermal convection from the EM Drive being able to produce the measured forces. Concerning <<Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects>>, yes the Pioneer anomaly was successfully explained by a team of JPL engineers/scientists on the basis of thermal radiation effects (not natural convection thermal effects). Thermal radiation, an entirely different (from convection) means of thermal transport, will take place even in a perfect vacuum, as thermal radiation is electromagnetic radiation and therefore does not need a gas or a fluid as a transport medium. On the other hand natural convection is completely dependent on fluid or gas medium to carry it, and without a fluid or a gas, there cannot be any thermal convection. Thermal convection involves fluid advection.Radiative heat transfer is the only form of heat transfer that can take place in a vacuum. Radiative heat transfer depends on the difference between the fourth power of the temperatures between the radiating surface and the irradiated surface, the surface areas and the emissivities of the radiating and irradiated surfaces and the Stefan–Boltzmann constant . It may be important for the Pioneer anomaly: an extremely small effect comprising an acceration towards the Sun, of only 8.74×10^(−10) m/s^2, due to asymmetrical radiation of heat from the Radioisotope thermoelectric generators or from the spacecraft electronics reflecting from the back of the spacecraft's dish-like main antenna, causing a recoil like sunlight striking a solar sail.But in the case of the EM Drive, how much does the temperature difference between radiated and irradiated surfaces have to be to to justify the measured thrust forces ?You are indeed right about the two thermal effects you mention, and I don't want to be pushed into territories that I don't master and that were not the subject of my initial post.However I believe (and in writing this, I do something stupid ) that thermal convection means implicitly that the mean molecular free path is negligible so thermal convection anyway can't exist at all at this pressure. However that doesn't means we should stop here. At 5*10-6 Torr there are still 5*10^11 molecules per cm3 and mean free path is in the 5m range. I did rule of thumb calcs (that indeed I will never publish ), and the thrust is still in the 5-10 µNewton range. My calcs are obviously wrong but indicate that one cannot conclude easily there is absolutely no thermal effect possible at 5*10-6 Torr.
Quote from: JPLeRouzic on 02/28/2015 12:51 pmQuote from: Mulletron on 02/27/2015 08:24 pmSo the vacuum did eliminate the thermal hypothesis....5*10-6 Torr is hardly a vacuum good enough to eliminate the thermal hypothesis. That's what you encounter at 1000 km high or so.Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects.@Mulletron must have meant "So the vacuum did eliminate the [natural convection] thermal hypothesis" . He wrote "thermal hypothesis" without the words "natural convection" because he thought that it was obviously understood he was referring to convection in the context he was discussing: what is the difference between ambient pressure and 5*10-6 Torr. Obviously this pressure makes a huge difference for natural convection currents, as a trivial calculation can show that 5*10-6 Torr vacuum does eliminate the natural convection hypothesis that was advanced in most media (including Prof. Baez's blog) as the most likely explanation for the measurements. @Frobnicat, was proposing the thermal convection hypothesis as a possible artifact, and he worked some equations in Thread 1. I do not recall @Frobnicat objecting to a 5*10-6 Torr vacuum nullifying the hypothesis of natural thermal convection from the EM Drive being able to produce the measured forces. ...
Concerning <<Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects>>, yes the Pioneer anomaly was successfully explained by a team of JPL engineers/scientists on the basis of thermal radiation effects (not natural convection thermal effects). Thermal radiation, an entirely different (from convection) means of thermal transport, will take place even in a perfect vacuum, as thermal radiation is electromagnetic radiation and therefore does not need a gas or a fluid as a transport medium. On the other hand natural convection is completely dependent on fluid or gas medium to carry it, and without a fluid or a gas, there cannot be any thermal convection. Thermal convection involves fluid advection.Radiative heat transfer is the only form of heat transfer that can take place in a vacuum. Radiative heat transfer depends on the difference between the fourth power of the temperatures between the radiating surface and the irradiated surface, the surface areas and the emissivities of the radiating and irradiated surfaces and the Stefan–Boltzmann constant . It may be important for the Pioneer anomaly: an extremely small effect comprising an acceration towards the Sun, of only 8.74×10^(−10) m/s^2, due to asymmetrical radiation of heat from the Radioisotope thermoelectric generators or from the spacecraft electronics reflecting from the back of the spacecraft's dish-like main antenna, causing a recoil like sunlight striking a solar sail.But in the case of the EM Drive, how much does the temperature difference between radiated and irradiated surfaces have to be to to justify the measured thrust forces ?
Quote from: Rodal on 02/28/2015 03:21 pmQuote from: JPLeRouzic on 02/28/2015 12:51 pmQuote from: Mulletron on 02/27/2015 08:24 pmSo the vacuum did eliminate the thermal hypothesis....5*10-6 Torr is hardly a vacuum good enough to eliminate the thermal hypothesis. That's what you encounter at 1000 km high or so.Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects.@Mulletron must have meant "So the vacuum did eliminate the [natural convection] thermal hypothesis" . He wrote "thermal hypothesis" without the words "natural convection" because he thought that it was obviously understood he was referring to convection in the context he was discussing: what is the difference between ambient pressure and 5*10-6 Torr. Obviously this pressure makes a huge difference for natural convection currents, as a trivial calculation can show that 5*10-6 Torr vacuum does eliminate the natural convection hypothesis that was advanced in most media (including Prof. Baez's blog) as the most likely explanation for the measurements. @Frobnicat, was proposing the thermal convection hypothesis as a possible artifact, and he worked some equations in Thread 1. I do not recall @Frobnicat objecting to a 5*10-6 Torr vacuum nullifying the hypothesis of natural thermal convection from the EM Drive being able to produce the measured forces. ...My specific proposition at the time was a pressure difference build-up between inside cavity and outside, enough to "jet" supposedly warmed air through small apertures of the cavity. I recall having said about 5 month ago I would give a definite answer within 2 month (so much for my credibility with deadlines). This specific "warm jet" hypothesis would have been easily nullified even by a very more modest rough vacuum level of a few Torr. So this specific hypothesis is now ruled out, and I'm glad the experimental progress at Eaglworks outpaced my episodic armchair scientist investment on that matter For anything pressure related (even complex anisotropic molecular flow like in a Crookes radiometer effect) a characteristic value would be an extreme case of a completely asymmetric pressure difference around 5e-6 Torr = 6.65e-4 Pa on a surface of 11'' diameter = 6.13e-2 m˛ (roughly, cross section of the frustum) that yields about 41µN. Unfortunately still in the ballpark of the signal... so maybe hardcore sceptics could still require 2 orders of magnitude better vacuum, just to be sure... (edit : I see JPLeRouzic reach similar conclusion)Anyway, it's clear that it becomes difficult to find remaining thermo-aerodynamic effects that would need better than 5e-6 Torr to be ruled out : this is good enough to put possible asymmetric gas flow effects much below the observed signal.QuoteConcerning <<Pioneer lives in a vacuum *one million* times better that 5*10-6 Torr and there are still thermal effects>>, yes the Pioneer anomaly was successfully explained by a team of JPL engineers/scientists on the basis of thermal radiation effects (not natural convection thermal effects). Thermal radiation, an entirely different (from convection) means of thermal transport, will take place even in a perfect vacuum, as thermal radiation is electromagnetic radiation and therefore does not need a gas or a fluid as a transport medium. On the other hand natural convection is completely dependent on fluid or gas medium to carry it, and without a fluid or a gas, there cannot be any thermal convection. Thermal convection involves fluid advection.Radiative heat transfer is the only form of heat transfer that can take place in a vacuum. Radiative heat transfer depends on the difference between the fourth power of the temperatures between the radiating surface and the irradiated surface, the surface areas and the emissivities of the radiating and irradiated surfaces and the Stefan–Boltzmann constant . It may be important for the Pioneer anomaly: an extremely small effect comprising an acceration towards the Sun, of only 8.74×10^(−10) m/s^2, due to asymmetrical radiation of heat from the Radioisotope thermoelectric generators or from the spacecraft electronics reflecting from the back of the spacecraft's dish-like main antenna, causing a recoil like sunlight striking a solar sail.But in the case of the EM Drive, how much does the temperature difference between radiated and irradiated surfaces have to be to to justify the measured thrust forces ?Very clear. For the last question, I would be tempted to say : temperatures needing 300 times the actual operating power of the system, since the force/power ratios are ~300 times better than a photon rocket. Unless the space between the frustum and the vacuum chamber's walls could amplify the effect by bouncing hotter IR photons around a few times and make high temperature, high radiation pressure "traps". IR photons are emitted around all the time, but at thermal equilibrium those radiative pressures have equal contribution on all side of an object in the bath. Anyone knows the typical reflectivity of more or less polished metals in thermal IR ? That would put an upper bound on the "boost" factor compared to the photon rocket equivalent thrust, likely much below 300.
@ RODALStill have question about the Shawyer "Demo" cavity w/ 174mN. What are the current estimates of the cone dimensions, frequency (3.85GHz?), and Q (6000 est?). When I put in TM02 and 450W, I get 174.8microN, rather than the 174milliN reported. I would like to recheck those numbers. Even w/ Q=45000, I need to get X up around (65 Very high mode) to get those numbers. Is that possible w/ 3.85GHz ??Thanks
Quote from: flux_capacitor on 02/28/2015 07:30 pm....Interesting thing to note: Shawyer claims the engine starts to accelerate only when the magnetron frequency locks to the resonant frequency of the thruster, following an initial warm up period where it does not move; thus according to him eliminating possible spurious forces.....That's very interesting stuff. Thank you for bringing it up.Do you have a reference as to where Shawyer made that interesting claim?
The frequency offset curve shows that initial magnetron thermal drift ends with frequency lock. At this point, 130 secs into the test run, the velocity data shows the start of acceleration under power. The prior thermal drift period, with no acceleration, shows that the thrust is not a result of spurious thermal effects. When the power is turned off, at 210 secs, there is a coast period as the slosh effects of 5kg of coolant maintain a reduced acceleration. This is followed by the deceleration due to the friction torque. A maximum velocity of 2cm/s was achieved and a total distance of 185cm was "flown".