Author Topic: EM Drive Developments Thread 1  (Read 762968 times)

Offline Stormbringer

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Re: EM Drive Developments
« Reply #280 on: 08/09/2014 06:49 AM »
i have seen people here pan fusion propulsion.; a likely near term advancement. i have seem them pan VASIMR and other advanced concepts that aren't that unlikely. i have even seen them argue about this or that chemical propulsion scheme being unrealistic or undesireable. so exactly what advanced concepts are non "woo woo?" to everyone's satisfaction? hamster flatulence? what?

Seems to me that everyone wants to talk about the stuff that has no hope of working and no-one ever wants to talk about the stuff that could be made to work with enough money. People used to love talking about solar sails, but now that one has flown (IKAROS) and two more are under development (Sunjammer and LightSail) suddenly no-one is interested anymore. Similarly, few people are terribly interested in talking about nuclear thermal rockets unless they're some impractical fusion contraption, but they were all the rage back in Heinlein's day. Reality has the nasty habit of boring the dreamers.
oh there are plenty of threads about all of those things and countless ones discussing this or that chemical scheme. but the ones that break new ground get a lot of grief. while in my opinion there is no purely chemical scheme that should be classified as advanced. solar sails sure. even though there are a lot of issues that are not easy to fix. plasma sails; ok I'll buy it; but they are leaky. NTRs? sure; but do it already. damn it we have had the knowledge from the 1960s. do it already or shaddap. Fusion? ok. there are some things that may be as few as 5 years off there. This other (what they think of as woo woo or oogly moogly) stuff? low probability of success but huge payoff upon success for not much effort or money. worth discussing. worth low level funding at least. It's not like it hurts funding for other projects. NASA won't launch one less probe because they gave Dr White some modest resources. Not one Orion was hurt in the making of his coil thingy.
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Offline Stormbringer

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Re: EM Drive Developments
« Reply #281 on: 08/09/2014 06:57 AM »
Dr White may have in fact gotten his funding by couch fishing in the employee break room chair cushions for all i know. It'd probably cover it.
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Offline Star One

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Re: EM Drive Developments
« Reply #282 on: 08/09/2014 09:30 AM »

i have seen people here pan fusion propulsion.; a likely near term advancement. i have seem them pan VASIMR and other advanced concepts that aren't that unlikely. i have even seen them argue about this or that chemical propulsion scheme being unrealistic or undesireable. so exactly what advanced concepts are non "woo woo?" to everyone's satisfaction? hamster flatulence? what?

Seems to me that everyone wants to talk about the stuff that has no hope of working and no-one ever wants to talk about the stuff that could be made to work with enough money. People used to love talking about solar sails, but now that one has flown (IKAROS) and two more are under development (Sunjammer and LightSail) suddenly no-one is interested anymore. Similarly, few people are terribly interested in talking about nuclear thermal rockets unless they're some impractical fusion contraption, but they were all the rage back in Heinlein's day. Reality has the nasty habit of boring the dreamers.

I think with solar sails it's more their slow pace of development, I am sure we were talking about these back in the eighties but they are still in the early stages of use. Unfortunately the internet seems easily bored with little patience for such projects.

Online sanman

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Re: EM Drive Developments
« Reply #283 on: 08/09/2014 12:47 PM »
i have seen people here pan fusion propulsion.; a likely near term advancement. i have seem them pan VASIMR and other advanced concepts that aren't that unlikely. i have even seen them argue about this or that chemical propulsion scheme being unrealistic or undesireable. so exactly what advanced concepts are non "woo woo?" to everyone's satisfaction? hamster flatulence? what?

Seems to me that everyone wants to talk about the stuff that has no hope of working and no-one ever wants to talk about the stuff that could be made to work with enough money. People used to love talking about solar sails, but now that one has flown (IKAROS) and two more are under development (Sunjammer and LightSail) suddenly no-one is interested anymore. Similarly, few people are terribly interested in talking about nuclear thermal rockets unless they're some impractical fusion contraption, but they were all the rage back in Heinlein's day. Reality has the nasty habit of boring the dreamers.

Even if it seems flimsy, people naturally want to look for some new possibility that can bypass some of the existing strictures that limit spaceflight. "But physics can't be bypassed," you say - well who can claim omniscient knowledge of physics? There may be small exploit opportunities which can be exposed here and there. The fact is that the Quantum Vacuum exists, and it interacts with everything in our world - without violating Conservation of Momentum. Maybe there's a way to push off it without expelling propellant, and maybe this device is demonstrating such an effect. It seems relatively straightforward to attempt a more thorough investigation to provide either proof or disproof that some kind of propulsive effect is happening.


Offline SteveKelsey

Re: EM Drive Developments
« Reply #284 on: 08/09/2014 04:02 PM »
Classical physics ( Newton plus Maxwell) thought it had the universe sewn up and all that was left was details and taxonomy. The view at the time was that it could explain everything, except for one little problem called black body radiation.
Through this small chink in the armour we got quantum mechanics, QED, and eventually the Standard Model. At the time, quantum mechanics was reviled by mainstream authocrats. QM seemed bizarre and irrelevant but something had to explain the odd and ' unscientific' results.

The  Standard Model is hugely successful, and full of holes. http://www.math.columbia.edu/~woit/wordpress/?p=5946&cpage=1
There is no single standard model. The current orthodoxy did not predict and currently cannot explain neutrino mass, entanglement, dark matter, dark energy,accelerated  inflation, the 'cold dark spot' the 'axis of evil'.
How many chinks in the armour of your orthodoxy do you need?
When  the fifty or so 'free parameters' and the need for normalisation have been removed then it might be possible to claim we understand everything. Until that point, experiment carefully and be prepared for surprises.
2001 is running a little late, but we are getting there.

Offline frobnicat

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Re: EM Drive Developments
« Reply #285 on: 08/09/2014 07:13 PM »
It's not that we know everything, but at some energy densities/scales the amount experience confirming the "laws" is so huge than when an experiments claims to see a phenomenon that is in apparent contradiction to those laws without resorting to high energy physics or cosmological scales then it is a sure bet to discard the said experiment at a glance of the summary : the explanation to make said anomaly real and yet compatible with already known results seems far too contrived and unnatural. For instance if someone claims that a fancy shape has slightly more buoyancy than the weight of fluid displaced by such shape, because of the shape, you would surely dismiss the claim without looking the details of the shape and measuring apparatus : Archimedes principle holds and will continue to hold whenever a macroscopic shape is immersed and stand still in a fluid, no matter how old beard physics or how fancy the shape. The good old principles are only broken when going beyond some scope of validity, say newtonian additivity of speed is broken, but only when approaching c, mass conservation is broken but only when taping into nuclear energy levels, the sum of the angles of a triangle is not 180 but only near very heavy compact objects, mass_energy conservation is apparently broken but only on cosmological space-time scales...
So yes we had quite a number of surprises last century or so but the absolute principles of 19th century and before stayed good principles, even as approximations, in their range of validity. What does the EMdrive to reach beyond the range of validity so well established for conservation of energy ? Pushing on vacuum virtual particles sounds nice but vacuum is lorentz invariant so far (it's not like possible violations have not been investigated : http://en.wikipedia.org/wiki/Modern_searches_for_Lorentz_violation) and pushing on a lorentz invariant "medium" is not only cheap momentum but basically "free energy", so you cannot claim that without claiming free energy, or some form of transfer of energy from vacuum zero point to the device, that would imply negative energy radiating (contrary to a static casimir effect gap), probably FTL I can't tell, but the point is the whole contemporary physics edifice is crumbling, you can't just borrow a little bit of cheap lorentz invariant momentum and keep the rest untouched.
The whole contemporary physics edifice will probably be extended/replaced some times ahead (and shown to be an approximation or limit to more general principles) but has shown enough validity in a wide range of scales/densities that a device that appear to be well within those ranges be met with utter skepticism by the tenants of the orthodoxy who have a view of the amazing consistency of the whole so far, even if "full of holes". This should be no surprise, this is not a scandal. If the thrust depended clearly on its orientation relative to the stars (aether wind) I guess this would be met with more curiosity as it could relieve the "free energy" aspect.
That said, while I would put my bet with the skeptics, well, you never know, I think this experience's results is worth elucidation, a week clearly is not enough for a small team to check a number of parameters against the values : what if in vacuum, what if changing place of device relative to chamber walls, what if adding another strong magnet somewhere else to the damping one, hell, what if halving the power, we don't even know if the effect would be linear ... would need hundreds measuring sessions. If only for advancing the know how of reliably measuring orthodox low or null thrusts when RF resonant cavities are involved somehow is worth more.

Online sanman

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Re: EM Drive Developments
« Reply #286 on: 08/09/2014 07:26 PM »
For the sake of argument, if the entire electrical input to the test apparatus had been converted into photons, then could the resulting photon rocket have generated comparable levels of force as what was observed?

Offline CW

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Re: EM Drive Developments
« Reply #287 on: 08/09/2014 07:42 PM »
I think one has to be careful when calling found physical principles 'laws'. They are not laws in the absolute sense, as in given by 'God', or being the final answer. The only thing we can say about the principles that we found and verified by peer-reviewed experiments up to any given point in time is: To the best of our current knowledge, this is what happens. A very important point to make.

When an experiment seems to 'violate' known physical 'laws', then one could also say instead: That experiment seems to demonstrate a behavior that, to the best of our current knowledge, should not occur. You see the difference that the wording makes? The first paraphrase pretends to be a prosecutor in court, immediately declaring anyone who goes against "that what we know so far" a criminal who 'violates' a 'law'. It is a funny position, because this is what it really says: Something was measured, that seems to go against that which we know to be 'true' - and since it is like that, it must be wrong. This is not how science works. For that to decide, there is peer-review.

I acknowledge that too many revolutionary inventions were claimed, in the biggest part by self-deluded individuals and oftentimes outright frauds. But when science becomes dogma, you can stop your work and go pray in a church. It would be time better spent.

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Offline CW

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Re: EM Drive Developments
« Reply #288 on: 08/09/2014 07:46 PM »
For the sake of argument, if the entire electrical input to the test apparatus had been converted into photons, then could the resulting photon rocket have generated comparable levels of force as what was observed?

That is an excellent question. I think that the difference lies in the fact that in a photon rocket, each photon that imparts impulse to the rocket, only gets reflected exactly one time. In a superconducting high-Q resonant cavity, the photons get reflected e.g. a billion times until they get lost. So, my best guess is: No, the levels of force should not be comparable at all, since the photons can impart an impulse to a compact cavity many millions or even billions of times per second. Quite a hefty multiplier.
« Last Edit: 08/09/2014 07:51 PM by CW »
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Online sanman

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Re: EM Drive Developments
« Reply #289 on: 08/09/2014 07:53 PM »
For the sake of argument, if the entire electrical input to the test apparatus had been converted into photons, then could the resulting photon rocket have generated comparable levels of force as what was observed?

That is an excellent question. I think that the difference lies in the fact that in a photon rocket, each photon that imparts impulse to the rocket, only gets reflected exactly one time. In a superconducting high-Q resonant cavity, the photons get reflected e.g. a billion times until they get lost. So, my best guess is: No, the levels of force should not be comparable at all, since the photons can impart an impulse to a compact cavity many millions or even billions of times per second. Quite a hefty multiplier.

That's what I figured the response would be - but doesn't Conservation of Momentum apply to a resonant cavity, no matter how many times photons bounce back and forth inside it? If those were pingpong balls bouncing back-and-forth inside a cavity, we'd say there was no net momentum imparted to the apparatus from all their bouncing, because of Conservation of Momentum.

So if the force level observed is greater than what a photon rocket would hypothetically create, then doesn't that imply that there's more going on here than what traditional physics would suggest? (eg. Q-thruster, some interaction with Quantum Vacuum, etc)
« Last Edit: 08/09/2014 07:54 PM by sanman »

Offline aero

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Re: EM Drive Developments
« Reply #290 on: 08/09/2014 08:15 PM »
For the sake of argument, if the entire electrical input to the test apparatus had been converted into photons, then could the resulting photon rocket have generated comparable levels of force as what was observed?

That is an excellent question. I think that the difference lies in the fact that in a photon rocket, each photon that imparts impulse to the rocket, only gets reflected exactly one time. In a superconducting high-Q resonant cavity, the photons get reflected e.g. a billion times until they get lost. So, my best guess is: No, the levels of force should not be comparable at all.

No. I already did that calculation. The problem with that is the jet energy which would result. If the force, F = mdot * Ve were caused by photons moving at the speed of light, then mdot = 3.04E-13 kg/s and the jet energy, E= mdot * Ve^2/2 = .5*F*Ve . That gives E =  13,670.54 J/s or watts for a drive power of 17 watts. So conservation of energy is violated.

I have imagined a different failure mode. I hope i'ts wrong because I really want the EM thruster to be real, and I wonder how an outfit with "Aeronautics" in its name could make such a mistake, but consider this.

The EM thruster has never been tested in vacuum, and they all have been leaky, that is, total air pressure inside and outside is equal and equals atmospheric. Imagine then that some mechanism sets up an air circulation within the EM thruster. Circulating air moves with some velocity V across the inside of the large end of the thruster, recirculating around the open cavity past the small end. Air pressure outside the large end = Pt, total pressure but static air pressure inside the large end, Ps = Pt -q and q = 0.5* rho*V^2.

I ran the numbers assuming 140 mm diameter, uniform velocity and sea level air density. The force of air pressure equals the thrust force claimed when V = ~0.1 m/s. The actual number Excel calculated was 95.74677721 mm/s.

I hope you can gently shoot down this idea.
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Offline CW

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Re: EM Drive Developments
« Reply #291 on: 08/09/2014 08:19 PM »
For the sake of argument, if the entire electrical input to the test apparatus had been converted into photons, then could the resulting photon rocket have generated comparable levels of force as what was observed?

That is an excellent question. I think that the difference lies in the fact that in a photon rocket, each photon that imparts impulse to the rocket, only gets reflected exactly one time. In a superconducting high-Q resonant cavity, the photons get reflected e.g. a billion times until they get lost. So, my best guess is: No, the levels of force should not be comparable at all, since the photons can impart an impulse to a compact cavity many millions or even billions of times per second. Quite a hefty multiplier.

That's what I figured the response would be - but doesn't Conservation of Momentum apply to a resonant cavity, no matter how many times photons bounce back and forth inside it? If those were pingpong balls bouncing back-and-forth inside a cavity, we'd say there was no net momentum imparted to the apparatus from all their bouncing, because of Conservation of Momentum.

So if the force level observed is greater than what a photon rocket would hypothetically create, then doesn't that imply that there's more going on here than what traditional physics would suggest? (eg. Q-thruster, some interaction with Quantum Vacuum, etc)

All that we can IMHO say so far is, that if the measurements are confirmed under better controlled conditions as well, that by some hitherto unknown physical interaction an imbalance in momentum transfer is produced and that the photons, which are reflected N times in this resonant cavity on the desired surface, get N times the opportunity to do a momentum transfer. If this really works, then it would make sense that, as Shawyer claims, such a drive would be the perfect means to produce a static force that counteracts the gravitational force of any kind of airborne objects.

There is one thing I find a bit curious. Momentum is defined as p = m*v . Now, if the drive were just to produce a force to counteract Earth's gravity, in how far is impulse conservation not adhered to? Above formula states clearly, that you need to have some relative speed going on for any kind of measurable momentum. No movement - no impulse. I mean, it is IMHO comparable to a book standing on a table. No-one would imply that the book were to 'violate' impulse conservation in any way ;) . So, what's going on here?

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Offline Stormbringer

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Re: EM Drive Developments
« Reply #292 on: 08/09/2014 08:42 PM »
For the sake of argument, if the entire electrical input to the test apparatus had been converted into photons, then could the resulting photon rocket have generated comparable levels of force as what was observed?

That is an excellent question. I think that the difference lies in the fact that in a photon rocket, each photon that imparts impulse to the rocket, only gets reflected exactly one time. In a superconducting high-Q resonant cavity, the photons get reflected e.g. a billion times until they get lost. So, my best guess is: No, the levels of force should not be comparable at all.

No. I already did that calculation. The problem with that is the jet energy which would result. If the force, F = mdot * Ve were caused by photons moving at the speed of light, then mdot = 3.04E-13 kg/s and the jet energy, E= mdot * Ve^2/2 = .5*F*Ve . That gives E =  13,670.54 J/s or watts for a drive power of 17 watts. So conservation of energy is violated.

I have imagined a different failure mode. I hope i'ts wrong because I really want the EM thruster to be real, and I wonder how an outfit with "Aeronautics" in its name could make such a mistake, but consider this.

The EM thruster has never been tested in vacuum, and they all have been leaky, that is, total air pressure inside and outside is equal and equals atmospheric. Imagine then that some mechanism sets up an air circulation within the EM thruster. Circulating air moves with some velocity V across the inside of the large end of the thruster, recirculating around the open cavity past the small end. Air pressure outside the large end = Pt, total pressure but static air pressure inside the large end, Ps = Pt -q and q = 0.5* rho*V^2.

I ran the numbers assuming 140 mm diameter, uniform velocity and sea level air density. The force of air pressure equals the thrust force claimed when V = ~0.1 m/s. The actual number Excel calculated was 95.74677721 mm/s.

I hope you can gently shoot down this idea.
i dunno if this EM thruster has been tested in vacuum or not but I know that Dr Woodward's version of this thing has been tested in vacuum.
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Offline Stormbringer

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Re: EM Drive Developments
« Reply #293 on: 08/09/2014 08:45 PM »
Dr Woodward's slide shows a vacuum strength of 5.0 milli Tor.
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Offline Hanelyp

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Re: EM Drive Developments
« Reply #294 on: 08/09/2014 08:52 PM »
That's what I figured the response would be - but doesn't Conservation of Momentum apply to a resonant cavity, no matter how many times photons bounce back and forth inside it? If those were pingpong balls bouncing back-and-forth inside a cavity, we'd say there was no net momentum imparted to the apparatus from all their bouncing, because of Conservation of Momentum.

So if the force level observed is greater than what a photon rocket would hypothetically create, then doesn't that imply that there's more going on here than what traditional physics would suggest? (eg. Q-thruster, some interaction with Quantum Vacuum, etc)
The forces inside a resonant chamber should be balanced, except for the feed point.  The transmission cable connecting the resonant chamber to the microwave generator is carrying momentum along with the energy.  If there's a poor match between feed line and resonator, photons bouncing back and forth may carry momentum far in excess of a single transfer of the energy.  This can be a problem for experimental integrity if the microwave generator is not on the force balance.

Offline aero

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Re: EM Drive Developments
« Reply #295 on: 08/10/2014 03:49 AM »
Back on the previous page, I pose a situation where air circulation inside the thruster caused the pressure difference measured as thrust. http://forum.nasaspaceflight.com/index.php?topic=29276.msg1241487#msg1241487

It occurs to me that this idea does not hold water because it was reported that with the dielectric RF resonator removed, the measurement was zero to the system precision. If air circulates with the resonator installed, then it should also circulate (to some extent) with the resonator removed, shouldn't it?
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Offline GregA

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Re: EM Drive Developments
« Reply #296 on: 08/10/2014 05:20 AM »

The forces inside a resonant chamber should be balanced, except for the feed point.  The transmission cable connecting the resonant chamber to the microwave generator is carrying momentum along with the energy.  If there's a poor match between feed line and resonator, photons bouncing back and forth may carry momentum far in excess of a single transfer of the energy.  This can be a problem for experimental integrity if the microwave generator is not on the force balance.
The null test should have also had similar error?

Offline su27k

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Re: EM Drive Developments
« Reply #297 on: 08/10/2014 03:18 PM »
Dr White's presentation on this recent work: http://new.livestream.com/accounts/4950775/events/3217776/videos/58616741, starts after 52 mins.

Offline Stormbringer

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Re: EM Drive Developments
« Reply #298 on: 08/11/2014 04:09 AM »
thanks for the link. i will actually watch the thing through later but from the description you gave it seems nothing new has happened since his last recorded presentation.


i was just thinking...

if Mach's principle worked via advanced waves and retarded waves as opposed to quantum flux or one of the other ideas... would that not mean that you also have an ansible because you could then modulate a mach drive so as to encode information in the advanced and retarded waves?
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Offline Stormbringer

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Re: EM Drive Developments
« Reply #299 on: 08/11/2014 08:45 AM »
i think Dr White said more about the EM drive this time. including details of the test rig power, measurements, calibration and so forth. if you can bear the crappy sound quality and the guy apparently expiring from TB in the background there is a lot in there to satisfy critics.

on the warp thing: his teams is quantifying and accounting for false signals. and has set up type of test for the warp thing involving time of flight measurements for a second laser beam. these measurement regimes take place at the same time so that false positives that affect one method generally don't affect the other.
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