Yeah... I'm not getting how this does not violate conservation of momentum and energy. For example if this works you should be able to construct a perpetual motion free energy machine. If constant electrical power produces constant acceleration you have a problem since kinetic energy increases with the square of velocity. You will quickly reach a point where your kinetic energy vastly exceeds the electrical energy input. Sorry, I smell the stench of cold fusion.
There is one joker in the pack. It seems force produced falls as the payload accelerates, so this is an engine with a "top speed" limit.
Quote from: watermod on 04/30/2015 04:46 pmIf one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?Sort of a sink or swim test.The problem with that would be the power requirement. Dr White's test setup produces something around 50-80 x 10^-6 N of force for 100w of input. The last time I checked triple junction PV cells have hit 43% and thin film types around 16%. A 4 wing roll out design would need 4 wings 10cm x about 1.3m, or 18 10x10cm plates of rigid plates. Either way you're looking at a fairly tricky mechanism construction job to unfold enough array to be useful.
If one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?Sort of a sink or swim test.
Quote from: john smith 19 on 04/30/2015 05:20 pmQuote from: watermod on 04/30/2015 04:46 pmIf one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?Sort of a sink or swim test.The problem with that would be the power requirement. Dr White's test setup produces something around 50-80 x 10^-6 N of force for 100w of input. The last time I checked triple junction PV cells have hit 43% and thin film types around 16%. A 4 wing roll out design would need 4 wings 10cm x about 1.3m, or 18 10x10cm plates of rigid plates. Either way you're looking at a fairly tricky mechanism construction job to unfold enough array to be useful. Just stick it in a shielded hermetic box, powered off a RC airplane battery on a timer, hang it off a hanging Cavendish style torsion pendulum (insensitive to shifts in CoM), and test it in different orientations to rule out magnetic effects. You'd be easily able to get all the drifts into sub-micronewton range with a fully shielded set up.That's a lot cheaper than a satellite and a positive result would be much more convincing.
Quote from: ppnl on 04/30/2015 05:24 pmYeah... I'm not getting how this does not violate conservation of momentum and energy. For example if this works you should be able to construct a perpetual motion free energy machine. If constant electrical power produces constant acceleration you have a problem since kinetic energy increases with the square of velocity. You will quickly reach a point where your kinetic energy vastly exceeds the electrical energy input. Sorry, I smell the stench of cold fusion. Again, as I said above, why are you assuming constant acceleration? Constant increase in kinetic energy would eliminate this objection, at the cost of requiring a fixed inertial reference frame to measure the kinetic energy against. Standard special relativity theory does not allow this, but some newer theories that are equivalent to special relativity in their observed effects do allow this.
The problem with that would be the power requirement. Dr White's test setup produces something around 50-80 x 10^-6 N of force for 100w of input. The last time I checked triple junction PV cells have hit 43% and thin film types around 16%. A 4 wing roll out design would need 4 wings 10cm x about 1.3m, or 18 10x10cm plates of rigid plates. Either way you're looking at a fairly tricky mechanism construction job to unfold enough array to be useful.
Quote from: Dmytry on 04/30/2015 04:33 pmQuote from: Star One on 04/29/2015 07:32 pmBefore we gets lots of questions about terrestrial applications.Quote18.Q. How can the EmDrive produce enough thrust for terrestrial applications?A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.The static thrust/power ratio is calculated assuming a superconducting EmDrive with a Q of 5 x 109. This Q value is routinely achieved in superconducting cavities.Note however, because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper). Whilst the EmDrive can provide lift to counter gravity, (and is therefore not losing kinetic energy), auxiliary propulsion is required to provide the kinetic energy to accelerate the vehicle.http://emdrive.com/faq.htmlOookaaaay. So I start up my 1000kg hover car, in Ecuador, in the spring, and I'm going to work, at the sunrise.See any problem with that? Let me spell it out just in case: unless this drive is pushing against Earth, Earth's orbital energy is increasing at a rate of about 300 megawatts (according to the Sun's rest frame). Worse if taking Sun's motion around the centre of the galaxy.We should be discussing the article, not an external link that we have nothing to do with. Star One seems addicted to posting as many links as his fingers will allow him!
Quote from: Star One on 04/29/2015 07:32 pmBefore we gets lots of questions about terrestrial applications.Quote18.Q. How can the EmDrive produce enough thrust for terrestrial applications?A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.The static thrust/power ratio is calculated assuming a superconducting EmDrive with a Q of 5 x 109. This Q value is routinely achieved in superconducting cavities.Note however, because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper). Whilst the EmDrive can provide lift to counter gravity, (and is therefore not losing kinetic energy), auxiliary propulsion is required to provide the kinetic energy to accelerate the vehicle.http://emdrive.com/faq.htmlOookaaaay. So I start up my 1000kg hover car, in Ecuador, in the spring, and I'm going to work, at the sunrise.See any problem with that? Let me spell it out just in case: unless this drive is pushing against Earth, Earth's orbital energy is increasing at a rate of about 300 megawatts (according to the Sun's rest frame). Worse if taking Sun's motion around the centre of the galaxy.
Before we gets lots of questions about terrestrial applications.Quote18.Q. How can the EmDrive produce enough thrust for terrestrial applications?A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.The static thrust/power ratio is calculated assuming a superconducting EmDrive with a Q of 5 x 109. This Q value is routinely achieved in superconducting cavities.Note however, because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper). Whilst the EmDrive can provide lift to counter gravity, (and is therefore not losing kinetic energy), auxiliary propulsion is required to provide the kinetic energy to accelerate the vehicle.http://emdrive.com/faq.html
18.Q. How can the EmDrive produce enough thrust for terrestrial applications?A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.The static thrust/power ratio is calculated assuming a superconducting EmDrive with a Q of 5 x 109. This Q value is routinely achieved in superconducting cavities.Note however, because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper). Whilst the EmDrive can provide lift to counter gravity, (and is therefore not losing kinetic energy), auxiliary propulsion is required to provide the kinetic energy to accelerate the vehicle.
QuoteThe problem with that would be the power requirement. Dr White's test setup produces something around 50-80 x 10^-6 N of force for 100w of input. The last time I checked triple junction PV cells have hit 43% and thin film types around 16%. A 4 wing roll out design would need 4 wings 10cm x about 1.3m, or 18 10x10cm plates of rigid plates. Either way you're looking at a fairly tricky mechanism construction job to unfold enough array to be useful.Perhaps the Dragon trunk section could be used as a platform for the test after separation from the capsule. I suppose this would require the addition of thrusters of some kind to control the orientation of the solar panels. Probably more effort than a dedicated satellite, but just a thought.
Quote from: punder on 04/30/2015 04:25 pmQuote from: Rodal on 04/30/2015 04:11 pmThere are several questions in this thread regarding the issue of free energy and the issue of acceleration. The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing. Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome? Thanks.It breaks conventional physics no matter what. If it breaks something too obvious, they adjust the theory to break something else instead.
Quote from: Rodal on 04/30/2015 04:11 pmThere are several questions in this thread regarding the issue of free energy and the issue of acceleration. The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing. Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome? Thanks.
There are several questions in this thread regarding the issue of free energy and the issue of acceleration.
Quote from: Dmytry on 04/30/2015 05:37 pmQuote from: john smith 19 on 04/30/2015 05:20 pmQuote from: watermod on 04/30/2015 04:46 pmIf one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?Sort of a sink or swim test.The problem with that would be the power requirement. Dr White's test setup produces something around 50-80 x 10^-6 N of force for 100w of input. The last time I checked triple junction PV cells have hit 43% and thin film types around 16%. A 4 wing roll out design would need 4 wings 10cm x about 1.3m, or 18 10x10cm plates of rigid plates. Either way you're looking at a fairly tricky mechanism construction job to unfold enough array to be useful. Just stick it in a shielded hermetic box, powered off a RC airplane battery on a timer, hang it off a hanging Cavendish style torsion pendulum (insensitive to shifts in CoM), and test it in different orientations to rule out magnetic effects. You'd be easily able to get all the drifts into sub-micronewton range with a fully shielded set up.That's a lot cheaper than a satellite and a positive result would be much more convincing.That will happen. This is not a secret technology controlled by a single guy claiming it works, or anything like that. The data on how to build one is in the open, accessible and feasible to replicate for anyone with enough resources and technical ability to do so. And given its "eppur si muove" type claims, it will unavoidably emerge to the light if it works or not, as long as people keep an open and transparent review process for the test setup and the results. And as more people perform replications on their own, they will certainly try this. So I'm really hopeful because we will soon known if it works, of if it was just a waste of time. Either way, we win (a revolutionary invention, or just knowledge).
Quote from: Mongo62 on 04/30/2015 05:30 pmQuote from: ppnl on 04/30/2015 05:24 pmYeah... I'm not getting how this does not violate conservation of momentum and energy. For example if this works you should be able to construct a perpetual motion free energy machine. If constant electrical power produces constant acceleration you have a problem since kinetic energy increases with the square of velocity. You will quickly reach a point where your kinetic energy vastly exceeds the electrical energy input. Sorry, I smell the stench of cold fusion. Again, as I said above, why are you assuming constant acceleration? Constant increase in kinetic energy would eliminate this objection, at the cost of requiring a fixed inertial reference frame to measure the kinetic energy against. Standard special relativity theory does not allow this, but some newer theories that are equivalent to special relativity in their observed effects do allow this.The observed effects are that laws of physics are invariant relative to Lorentz boosts. Maxwell equations of electromagnetism are explicitly invariant relative to Lorentz boosts. This is a purely electromagnetic device. Which part of Maxwell equations is wrong?
Skepticism and Closed Mindedness are not the same thing. The first is an important frame of mind in scientific investigation; the second is antithetical to science.At the close of the 19th century, virtually every physicist alive was of the belief that everything that could be learned about physics was already known. As described in Thomas S. Kuhn's The Structure of Scientific Revolutions, the world of physics was about to be turned on its head. There were more than a few who accepted neither Relativity nor Quantum Mechanics. The skeptics needed to see the proof, but a skeptic examines evidence and accepts it if reasonable. A closed minded person refuses to abandon old models, in spite of new evidence to the contrary.For over a century now, physics has found itself in limbo, a no man's land of seemingly irreconcilable contradiction between Relativity and Quantum Mechanics. Much has been learned and new discoveries continue to happen, but there is not yet a Unified Field Theory, nor a Grand Unified Field Theory, nor a Theory of Everything (each of those has a different meaning). String Theory is the leading candidate at the moment, yet there are over ten differing models of how String Theory might work. The theory of Loop Quantum Gravity is the second favored theory, and then there are lesser known theories such as Garrett Lisi's E8 Theory.What we understand about the fabric of spacetime, about the Quantum Vacuum is still very limited. We do, however, know that it is something and not nothing. And yet we do not need fully to understand a phenomenon in to make use of it. Roentgen put X-Rays to use long before the mechanism behind their production was understood. In like manner, it is entirely possible that EM Drive may work and that it may be put to use before the entirity of the physics behind it is fully understood.Reactions in this thread range from exuberance to completely closed minds. Science is not about jumping to conclusions, either that a theory is correct or that it is incorrect. Science is about approaching a hypothesis with an open mind, a neutrality regarding belief. It embraces a healthy skepticism for results that tend to be extreme outliers, but does accept them if they are shown to be independently repeatable by other scientists.We used to ask whether the expanding universe had enough inertia to continue expanding forever at a decreasing rate, or if it would stop expanding and all mass implode into one singularity. Only recently did we discover the inflation is ocurring at an accelerating rate, leading us to theorize Dark Energy. It is all about the evidence. We have to follow the evidence. Whether we think this is the next great breakthrough in science or whether we think this is absurd, neither matters. This is not about opinion. What matters is the evidence. At present, there is no proof this is impossible, and there is no proof it is possible. We have to follow the evidence.
It is not close mindedness to point out that violating conservation of energy and momentum create massive problems for the supposed effect. This is especially true when many of the proponents do not understand that the conservation laws are being violated or understand the consequences of those violations.
It is not close mindedness to point out that violating conservation of energy and momentum create massive problems for the supposed effect. This is especially true when many of the proponents do not understand that the conservation laws are being violated or understand the consequences of those violations.Cold fusion should have taught us to be very very skeptical of these types of revolutionary results. Instead I suspect we will see people claiming that the EM drive finally explains where the excess energy in cold fusion comes from.It isn't impossible that there is something interesting here. It is just very very unlikely. This combination of low probability and high desire creates a strong possibility of self deception.
Quote from: Ludus on 04/30/2015 04:38 amWhat's the cheapest EM spacecraft design that should do clearly impossible things?About $10,000. You could Kickstarter it and get it on the next Dragon flight, ala A3R. Heck, there's cubesats that have flown for less.
What's the cheapest EM spacecraft design that should do clearly impossible things?