To be honest, I expected a LOT more of that sort of comment, especially on an unforgiving (mean that in the best possible way) hardcore space site like ours.
It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.
Supposing for a moment that this does actually work and space travel is eventually simpler than travelling between continents at the moment, it's going to highlight a few questions. If you can zoom around the solar system using the product of an afternoon in the High School Metal Shop, then why haven't we been awash in vistors from nearby star systems?
Secondly, how much acceleration could this thing conceivably kick out?
If you pour juice into it will it just keep accelerating? What's the limit to that? How many G's can it sustain and for how long? Are we looking at a torchship, but just without the torch?
There are several questions in this thread regarding the issue of free energy and the issue of acceleration.
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.
I go with "Extraordinary claims require extraordinary evidence". The claim here defies known laws of physics. Therefore, the evidence must be very conclusive. So far, the evidence is enough to support further investigation, but not enough to believe the claim is true. As exciting as this is, there are tons of examples where extraordinary claims were crumbled to dust. Most recently: faster than light neutrinos, primordial gravitational waves, etc.There are some extraordinary claims that came true though, bending of light through gravity, microwave background, etc. But these examples are VERY rare. Far rare than extraordinary claims that could not have been supported. So I will remain skeptical until there is really conclusive evidence. But I absolutely support the idea to generate this evidence, or at least try to.
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.
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.
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.
QuoteThe 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.Quoting 'papers' which have not been peer-reviewed, published, presented before a skeptical, disinterested audience, etc. etc. is of little value beyond this limited enclave of sci-fi enthusiasts.
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: 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?
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.I have read those objections. They all seem to be working from an unstated assumption: that the device produces a constant thrust and therefore acceleration for a given power input. If that were the case, then the kinetic energy would indeed eventually exceed the total input of energy into the drive.So the obvious solution is that for a given energy input, thrust is not linear, but delta kinetic energy is linear instead. So as the kinetic energy increases, the thrust for a given power input would decrease, but the kinetic energy imparted would continue to increase at a steady rate over time.This would mean that trip times for a given input energy would be longer than in the article, but you still avoid the negative effects of the rocket equation, so they remain a lot better than with conventional propulsion.