@TomH:This guy: a_langwich
“Eppur si muove“While it is interesting to theorize on how and why EM may work and even more interesting to speculate on what the ramifications and applications of EM may be I would suggest that it is far more important to adequately fund experimental research to prove or disprove that it works at all. I know that there are many unfunded and underfunded questions in fundamental and theoretical physics that many feel are more important than EM but it would seem to me that clear focus on experimental tests for EM can be done at a fraction of the cost of most others. NASA and other national space agencies are the most likely to benefit immediately from such research and are the logical agencies to fund such research. All the arguments I have seen against EM rest on the lack of theoretical foundations, but eppur si muove! I remain a hopeful skeptic. Hopefully further funding will become available as public interest grows.
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.
6.Q. Is the EmDrive a form of perpetual motion machine?A. The EmDrive obeys the law of conservation of energy and is therefore not a perpetual motion machine. Energy must be expended to accelerate the EmDrive (see Equation 16 of the theory paper). Once the EmDrive is switched off, Newton’s laws ensure that motion is constant unless it is acted upon by another force.http://emdrive.com/faq.html
What's the cheapest EM spacecraft design that should do clearly impossible things?
The reason why the picture shown in the article was chosen is because it is the picture that appears on a NASA report authored by Dr. White. The picture you posted in your post, instead, has "All Rights Reserved" by the artist, Mark Rademaker, a term of art used by artists and content creators to prevent ambiguity and clearly spell out the warning that their content cannot be copied freely. It has not appeared (to my knowledge) in that form, in a NASA report.
I find myself skepitcial as well - but that's based on the old adage “When you hear hoofbeats, think of horses, not zebras”
Quote from: CW on 04/30/2015 09:49 amQuote from: KelvinZero on 04/30/2015 09:22 amcan anyone explain this point better?from http://emdrive.com/faq.htmlQ. Why does the thrust decrease as the spacecraft velocity along the thrust vector increases?A. As the spacecraft accelerates along the thrust vector, energy is lost by the engine and gained as additional kinetic energy by the spacecraft. This energy can be defined as the thrust multiplied by the distance through which the thrust acts. For a given acceleration period, the higher the mean velocity, the longer the distance travelled, hence the higher the energy lost by the engine.This loss of stored energy from the resonant cavity leads to a reduction in Q and hence a reduction of thrust.The key question is why can't you just turn the machine off and start again from a new reference frame, giving you a traditional interpretation of a propellentless drive and free energy.Reading that Q/A, ascribing a 'book-keeping' ability to such a device in regards to reference frames sounds unphysical to me. I can't do anything with that. I tend to believe that Mr. Shawyer might have accidentally found something mind-blowing.. but his explanations just don't add up. It might work for, uh, different reasons than he assumes.Well you might ask how the electrons in the double slit experiment know they are being observed and therefore act differently.
Quote from: KelvinZero on 04/30/2015 09:22 amcan anyone explain this point better?from http://emdrive.com/faq.htmlQ. Why does the thrust decrease as the spacecraft velocity along the thrust vector increases?A. As the spacecraft accelerates along the thrust vector, energy is lost by the engine and gained as additional kinetic energy by the spacecraft. This energy can be defined as the thrust multiplied by the distance through which the thrust acts. For a given acceleration period, the higher the mean velocity, the longer the distance travelled, hence the higher the energy lost by the engine.This loss of stored energy from the resonant cavity leads to a reduction in Q and hence a reduction of thrust.The key question is why can't you just turn the machine off and start again from a new reference frame, giving you a traditional interpretation of a propellentless drive and free energy.Reading that Q/A, ascribing a 'book-keeping' ability to such a device in regards to reference frames sounds unphysical to me. I can't do anything with that. I tend to believe that Mr. Shawyer might have accidentally found something mind-blowing.. but his explanations just don't add up. It might work for, uh, different reasons than he assumes.
can anyone explain this point better?from http://emdrive.com/faq.htmlQ. Why does the thrust decrease as the spacecraft velocity along the thrust vector increases?A. As the spacecraft accelerates along the thrust vector, energy is lost by the engine and gained as additional kinetic energy by the spacecraft. This energy can be defined as the thrust multiplied by the distance through which the thrust acts. For a given acceleration period, the higher the mean velocity, the longer the distance travelled, hence the higher the energy lost by the engine.This loss of stored energy from the resonant cavity leads to a reduction in Q and hence a reduction of thrust.The key question is why can't you just turn the machine off and start again from a new reference frame, giving you a traditional interpretation of a propellentless drive and free energy.
What is the image of the bus-sized spacecraft pictured in the feature article? Who came up with that? It looks like a discarded blueprint from the modelshop of Zombies of the Stratosphere!