Author Topic: Propellantless Field Propulsion and application  (Read 664294 times)

Offline Giovanni DS

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Re: Propellantless Field Propulsion and application
« Reply #1240 on: 03/29/2011 12:40 PM »
Ignoring the fact that you're simply wrong for a moment, so what if it has?

Do you think the millions to billions of dollars required to make this functional are going to start flowing just because of a lab demonstration?

Assuming that it works (and I am not positive about this), we would be talking about a *propellantless* propulsion system, money should start flowing as soon as possible because it could be a strategic technology.

Without this kind of breakthrough wasting money in "human space exploration" is simply pointless. Chemical rockets will bring you nowhere except a little beyond LEO regardless the amount of money spent. The better you can hope for is a flags and footprints mission on Mars and that is all.

Without a breakthrough money would be better spent here on Earth IMO, watching rockets is fun but it is in research that money should go.

Giovanni
« Last Edit: 03/29/2011 12:41 PM by Giovanni DS »

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1241 on: 03/29/2011 01:51 PM »
Quote
Emdrive is a working system.

No, it is not.

There's several very good reasons why this is so.  First, there's no independent confirmation.  Second, the term "working system" is so broad as to be meaningless, and is readily dismissed.

So first:  OK, nobody else has done this, but is that because they can't or won't, or [cue dramatic music] they are being kept from demonstrating the validity of Shawyer's theory?  I know that there's all sorts of conspiracies out there, since I get the Illuminati newsletter regularly. So it's not like I don't have a soft spot for conspiracies.

One of the simplest explanations for the lack of funding for Emdrive is the conspiratorial one.  ATK, just to pick a rocket company completely at random, is not at all interested in competition, so I'd expect that their lobbyists would, if they thought it worth paying attention to, counsel lawmakers that Shawyer's work is untenable, and shouldn't be funded.  This shouldn't be difficult, since their rocket produces 12.5MN of thrust, and Shawyer's contraption, which isn't even a rocket, only several hundred mN of thrust.

It's hard for me to think that there's a "clear path to space" with this drive, and that Shawyer is some victim of a conspiracy.

But secondly:  What the farouk (pardon the Arabic) does "working system" mean?  In this case, nothing, I'd say.  If the "system" being described is a mechanism for slowly rotating large laboratory apparati on frictionless bearings, then I'd have to say without equivocation, that he's got a "working system".  But if "working sysworking sat stationkeeping thrust assembly, then no, it is not a working system.

There is not a logical chain of thought which starts with "Emdrive is not a working system" and ends with "therefore propellantless propulsion will never be made a reality".  Which is a roundabout way of saying, don't blame me; I'm not holding anybody back; but at the same time, nobody's "proved" anything yet. 

If a system can be found which converts electrical energy directly into forward momentum without expelling mass, that would be a good thing for spaceflight.  And a pretty major discovery in and of itself.  Worthy of a Nobel prize, after the discovery has been proven, not before.  Which is unlike their criteria for the Peace prize, whose current holder has been actively leading two wars, and has recently started another one.  But I digress.

I'd say that the experimental video which shows this device slowly rotating, without apparently pushing on anything, to be impressive in a lot of ways.  But if it said that "NASA agrees that it works", there would have to be a NASA citation proving that statement.  Will that statement be forthcoming?  'Cause I'm not going to give that statement any credit otherwise.  Also, I just watched a video.  Don't expect me to say that something has been proven on that basis.  'Cause I have no idea if he's proven anything or not.

Quote
Do you think the millions to billions of dollars required to make this functional are going to start flowing just because of a lab demonstration?

Well, uhhh, yeah.

Otherwise, I'd have to ask what is the point of lab demonstrations to funding agencies in the first place?

Which is not the same as saying that this particular demonstration was a demonstration to funding agencies.
Sometimes I just flat out don't get it.

Offline mikorangester

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Re: Propellantless Field Propulsion and application
« Reply #1242 on: 03/30/2011 03:17 AM »
Whatever. The science is proven and it works. Hopefully they start perfecting it and Darpa may actually one day get their "transportation vehicle that can drive and fly"

(https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&id=be792877dbda574d29f703d3f6ca06d0&_cview=0)

Offline aceshigh

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Re: Propellantless Field Propulsion and application
« Reply #1243 on: 03/30/2011 06:46 AM »
repeat 100 times the phrase "the science is proven" and it will magically be proven!!!

I will believe when they produce a prototype that can accelerate in a liner, not circular, motion.

like one user in Youtube commented on the video of the EMDrive: "my washing machine can do this".

Online QuantumG

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Re: Propellantless Field Propulsion and application
« Reply #1244 on: 03/30/2011 07:47 AM »
Otherwise, I'd have to ask what is the point of lab demonstrations to funding agencies in the first place?

What indeed.. think about it, you have in your possession a revolutionary technology which flies in the face of not only conventional practice but also conventional physics.. do you a) tell everyone about it or b) keep it secret and tell only who you need to in order to make it practicable? 

(sidenote: If you chose "a" because you think your patents are going to protect you, then you don't understand how the patent system works).

Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1245 on: 03/30/2011 01:57 PM »
There's nothing wrong with circular motion; that's what electric motors do.  Here on Earth, it is child's play to make "Things that Go!".  Without gravity, atmo or friction, it would be a different type of complexity.  They could probably rig up a battery of flywheels, and get them spinning at various speeds, and convert the angular momentum into forward momentum.

But I didn't take the emdrive video to postulate rotary motion only.  Certainly, linear thrust along the tangent to a circle results in, well, circular motion.  It's a tiny force; in order to even measure it, ya gotta use a friction-free bearing.  (And by friction free, I mean that the friction is, well, free.  Comes with the apparatus)  The experiment purports to have demonstrated some work, as narrowly defined in a thermodynamic sense.   A couple hundred mN's of thrust.  I keep forgetting; how much thrust has Woodward discovered or claimed?

The patent system in our country is broken, as witnessed by the patenting of genes of individual humans, taking what can only be called one of the most basic properties away from an individual.  But I digress.

Most members of the scientific group would not accept the term "whatever", a term that I probably overuse in the political realm, as the equivalent of the scientifically, narrowly defined term "proof".
Sometimes I just flat out don't get it.

Online QuantumG

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Re: Propellantless Field Propulsion and application
« Reply #1246 on: 03/31/2011 12:40 AM »
They could probably rig up a battery of flywheels, and get them spinning at various speeds, and convert the angular momentum into forward momentum.

Facepalm. 
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline mlorrey

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Re: Propellantless Field Propulsion and application
« Reply #1247 on: 03/31/2011 04:00 AM »
They could probably rig up a battery of flywheels, and get them spinning at various speeds, and convert the angular momentum into forward momentum.

Facepalm. 

Yeah, John, that doesnt work, the time averaged inertia cancels out. This is an experiment I actually did over a decade ago, with a couple different designs, one mechanical, one hydraulic. You can't extract momentum like you are describing unless the masses involved are varying their speeds at high percentages of light speed, where relativity causes mass variations.

This is basically how one of the terms in the Mach Effect equation works, with the electrons in the capacitors bulk mass varying due to relativity over the course of the charge/discharge cycle.
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Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1248 on: 03/31/2011 01:11 PM »
They could probably rig up a battery of flywheels, and get them spinning at various speeds, and convert the angular momentum into forward momentum.

Facepalm. 

It took about 30 seconds to type that, and that time would represent the level of analysis as well.  It would not represent my hold on the opinion.  I keep trying to believe in the conversion of electrical energy to forward momentum.  The only way, according to my next 30 second analysis, that the M-E drive could work, would be if it were harnessing relativistic effects.

Please don't complain about the 30 second analysis intervals in this lone example, which is atypical for me, or I might complain about the power consumed to barely distinguish the claimed movement from the background noise, which other, more thorough analysts have also noticed.
Sometimes I just flat out don't get it.

Offline kkattula

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Re: Propellantless Field Propulsion and application
« Reply #1249 on: 03/31/2011 01:41 PM »
...
I keep trying to believe in the conversion of electrical energy to forward momentum. 
...

What's belief got to do with it? I hope it works but I wait to see evidence, and practical application.

e.g. I don't believe my car works, I know it from experience.

Belief is only necessary to justify an emotional stance, when there is insufficient evidence.

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1250 on: 04/02/2011 01:12 PM »
Having thought a bit more:  Gyroscopic ACS is widely used for satellites.  Is that active principle only angular momentum?  Which would mean that circular motion is only good on the surface of a planet, where gravity and friction provide that which must be pushed upon.
Sometimes I just flat out don't get it.

Offline mlorrey

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Re: Propellantless Field Propulsion and application
« Reply #1251 on: 04/03/2011 03:02 AM »
Having thought a bit more:  Gyroscopic ACS is widely used for satellites.  Is that active principle only angular momentum?  Which would mean that circular motion is only good on the surface of a planet, where gravity and friction provide that which must be pushed upon.

Satellites use gyroscopes only to provide signals to attitude control systems. A separate technology is that of the momentum wheel, which is like a gyroscope and is used to store angular momentum and translate it, so a spacecraft can roll/yaw/pitch without using thrusters (why momentum wheels aren't used on shuttle, dragon, etc rather than the thruster systems, I do not know). One example of its use is on Hubble, which can't use thrusters due to its long life in orbit as well as the need to keep the optics free of exhaust gasses. Momentum wheels are also useful for despinning satellites that are put into orbit by spin stabilized upper stages.

You can't use the momentum in momentum wheels to create linear thrust because the satellite isn't on a planetary surface, and it can't push against itself. Momentum wheels still obey laws of action and reaction (which is why they are often also called reaction wheels).
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Offline mlorrey

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Re: Propellantless Field Propulsion and application
« Reply #1252 on: 04/03/2011 03:04 AM »
...
I keep trying to believe in the conversion of electrical energy to forward momentum. 
...

What's belief got to do with it? I hope it works but I wait to see evidence, and practical application.

e.g. I don't believe my car works, I know it from experience.

Belief is only necessary to justify an emotional stance, when there is insufficient evidence.

Conversely, I keep seeing evidence that it works, my disbelief is reserved for those who continue to deny that it works despite the evidence.
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Offline GeeGee

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Re: Propellantless Field Propulsion and application
« Reply #1253 on: 04/03/2011 08:29 PM »
I found this comment on physicsforums.com pertaining to Dennis Sciama:

"Note that linear frame-dragging works like inertia, in that a test object experiences a force proportional to its mass m if nearby objects are accelerating relative to it. It would be very neat if this could be extended so that when everything in the universe is accelerating relative to it with average acceleration a, it experiences a force exactly equal to ma. From the point of view of the rest of the universe, that force would then appear to be due to the inertia of the test object opposing its acceleration (in the opposite direction), and requires an equal and opposite force to maintain the acceleration. This is pointed out in Dennis Sciama's 1953 paper "On the Origin of Inertia". This idea is one of the possible simplifications that would arise from a gravity theory that satisfies Mach's Principle.

Unfortunately, it can be shown that in GR this "Sum for inertia" of the effects of the individual accelerations cannot exactly duplicate this effect, mainly because in GR the gravitational constant G is fixed, but the sum depends on the distribution of the masses of the universe and therefore cannot be fixed. This means that either this neat Mach's Principle model is wrong or GR is wrong. (I personally suspect that GR is an approximation which is very accurate at the solar system scale but very inaccurate at larger scales)."

Is this accurate? If Dennis Sciama's model is correct, then it invalidates GR? Can someone explain?
« Last Edit: 04/03/2011 08:30 PM by GeeGee »

Offline cuddihy

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Re: Propellantless Field Propulsion and application
« Reply #1254 on: 04/03/2011 09:00 PM »
.
Unfortunately, it can be shown that in GR this "Sum for inertia" of the effects of the individual accelerations cannot exactly duplicate this effect, mainly because in GR the gravitational constant G is fixed, but the sum depends on the distribution of the masses of the universe and therefore cannot be fixed. This means that either this neat Mach's Principle model is wrong or GR is wrong. (I personally suspect that GR is an approximation which is very accurate at the solar system scale but very inaccurate at larger scales)."

Is this accurate? If Dennis Sciama's model is correct, then it invalidates GR? Can someone explain?

Hard to say, I have no idea what explanation this comment is referring to by "it can be shown."

I think in Woodward's derivation that the statement "the sum depends on the distribution of the masses of the universe and therefore cannot be fixed" would be dismissed pretty easily -- in fact I think IIRC effectively the distribution of the masses in the universe is fixed, due to the increasing effect of the greater amount of mass at greater distances. So in other words, although it is NOT fixed, it is close enough for GR to see no difference.

In fact it's parallel to the argument that first-time viewers of ME theory often raise, that if inertia was gravitational in nature, you would see the effect of local masses (such as the earth, Jupiter, or the Sun,) very easily because they are so close. In fact Woodward shows via calculation that, counter-intuitively, the local masses actually have a 9-to-10 orders of magnitude smaller effect than the  "distant far-off active mass," (i.e. all other mass inside the observeable universe horizon), despite their much farther average distance, due to the (literally) overwhelming mass differential of the rest of the mass.

So basically from the viewpoint of any local mass, "G" is effectively fixed. There's just no way to observe a difference. So GR is valid even in an ME universe.

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #1255 on: 04/04/2011 01:52 AM »
No way to observe the difference?  How useful a property is that?
Sometimes I just flat out don't get it.

Offline kkattula

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Re: Propellantless Field Propulsion and application
« Reply #1256 on: 04/04/2011 03:52 AM »
No way to observe the difference?  How useful a property is that?

God: "I'm sorry, you want the Universe to be useful now, too?"  ;)

Offline sanman

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Offline GeeGee

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Re: Propellantless Field Propulsion and application
« Reply #1258 on: 04/04/2011 06:17 AM »


Hard to say, I have no idea what explanation this comment is referring to by "it can be shown."

I think in Woodward's derivation that the statement "the sum depends on the distribution of the masses of the universe and therefore cannot be fixed" would be dismissed pretty easily -- in fact I think IIRC effectively the distribution of the masses in the universe is fixed, due to the increasing effect of the greater amount of mass at greater distances. So in other words, although it is NOT fixed, it is close enough for GR to see no difference.

In fact it's parallel to the argument that first-time viewers of ME theory often raise, that if inertia was gravitational in nature, you would see the effect of local masses (such as the earth, Jupiter, or the Sun,) very easily because they are so close. In fact Woodward shows via calculation that, counter-intuitively, the local masses actually have a 9-to-10 orders of magnitude smaller effect than the  "distant far-off active mass," (i.e. all other mass inside the observeable universe horizon), despite their much farther average distance, due to the (literally) overwhelming mass differential of the rest of the mass.

So basically from the viewpoint of any local mass, "G" is effectively fixed. There's just no way to observe a difference. So GR is valid even in an ME universe.

Thanks. I wonder if this person is aware of Derek Raine's 1981 paper that Woodward often cites.

The same poster actually had a critique of Woodward's conjecture (keep in mind he does seem to support Sciama's origins of inertia):

"After reading the patent and some of the other material, in particular the paper "MACH’S PRINCIPLE, MASS FLUCTUATIONS, AND RAPID SPACETIME TRANSPORT" linked from Woodward's web site, I'm extremely sceptical.

In Special Relativity, all four components of four-momentum (that is, energy and linear momentum) are locally conserved at the microscopic level, with an equation of continuity. This also applies locally within GR, and is thought to apply on a larger scale too although there is some difficulty in describing this in GR because gravitational energy cannot be localized in a unique way.

It is certainly true that local conservation rules do NOT apply to rest mass, but Newton's law applies to total energy rather than rest mass, so this isn't relevant.

What may not be immediately clear is that this means that if energy is supplied to something by any means, regardless of whether it is via wires, pipes, axles, fields or whatever, then any change in energy or momentum must flow through that route.

For example, if you look up "dipole gravity" you'll find that many years ago Eue Jin Jeong had an idea that if you spin up a hemispherical object around its axis of symmetry, you will shift the center of mass slightly along the axis because of relativistic considerations. (This can be better illustrated by considering an axle with two wheels on it of the same mass but different radii, so one gets more rotational kinetic energy than the other as the rotation rate increases). It is true that the center of mass of the system shifts, but if you use Special Relativity to analyze the details of how the torque is applied through the axis, you will find that if the assembly were free to slide along its axis, it would shift to keep the center of mass in the same place, and a force has to be applied to prevent that from happening, so there is no overall shift of the center of mass. (However, Eue Jin Jeong has ignored this analysis and is now apparently trying to profit from this idea).

Similarly, I think Woodward must be ignoring some part of the energy or momentum flow to achieve his result. For example, it appears that he thinks that there is a loophole related to dm/dt terms in Newton's law. However, this isn't relevant, because the microscopic conservation of four-momentum is exact, and even if the calculations in difficult cases involve extra terms, these cancel out when you consider the flow of energy from one described system to another.

Similar ideas relating to unbalanced forces in sufficiently complex systems such as gyroscopes have been presented many times before (such as in the "Dean Drive" and ideas from Eric Laithwaite). In each case, a complex calculation appears to show unbalanced terms. However, as four-momentum is locally conserved, any such effect must be due to an incomplete or incorrect calculation, even if it is very difficult to find a specific error.

This means that if there is any possibility of some propellantless drive, it cannot arise from combining existing physical effects in a new complicated way, as all of those physical effects are known to be subject to the local conservation rules. It can only arise from new physics."


Offline mlorrey

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Re: Propellantless Field Propulsion and application
« Reply #1259 on: 04/04/2011 09:38 AM »
I found this comment on physicsforums.com pertaining to Dennis Sciama:

"Note that linear frame-dragging works like inertia, in that a test object experiences a force proportional to its mass m if nearby objects are accelerating relative to it. It would be very neat if this could be extended so that when everything in the universe is accelerating relative to it with average acceleration a, it experiences a force exactly equal to ma. From the point of view of the rest of the universe, that force would then appear to be due to the inertia of the test object opposing its acceleration (in the opposite direction), and requires an equal and opposite force to maintain the acceleration. This is pointed out in Dennis Sciama's 1953 paper "On the Origin of Inertia". This idea is one of the possible simplifications that would arise from a gravity theory that satisfies Mach's Principle.

Unfortunately, it can be shown that in GR this "Sum for inertia" of the effects of the individual accelerations cannot exactly duplicate this effect, mainly because in GR the gravitational constant G is fixed, but the sum depends on the distribution of the masses of the universe and therefore cannot be fixed. This means that either this neat Mach's Principle model is wrong or GR is wrong. (I personally suspect that GR is an approximation which is very accurate at the solar system scale but very inaccurate at larger scales)."

Is this accurate? If Dennis Sciama's model is correct, then it invalidates GR? Can someone explain?

Doesnt invalidate GR< but if the constant G isn't fixed, and instead depends on the distribution of masses in the universe, then everything is fine. The important thing to understand is that from any given point in the universe, the distribution of mass around any chosen point averages out to a fairly constant value, i.e. there isn't more mass on one side of the universe than the other from any given point.
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