Author Topic: Propellantless Field Propulsion and application  (Read 690048 times)

Offline cuddihy

  • Full Member
  • ****
  • Posts: 800
  • Liked: 143
  • Likes Given: 148
Re: Propellantless Field Propulsion and application
« Reply #1400 on: 07/08/2011 11:55 PM »

Cuddihy:

"It's not clear to me, for instance, why the runs are done as a frequency sweep -- it seems like a distractor. Why not do the runs at a rectified constant frequency where the stack is most resonant? Wouldn't that provide the clearest "thrust" signal?"

The problem with the constant drive frequency approach, which Woodward followed in some of his 2002 IIT test series, see attached report, is that the mechanical resonant frequency shifts with increasing PZT-Stack temperature.  Since these EDO EC-65 PZT-Stack caps have a Dissipation Factor (DF) of over 2.0% and a thermal conductivity of only about 1/300 that of copper, they heat up very fast when dissipating the couple of hundreds of RF Watts driving them.  So it turns out that frequency sweeping the stack over the noted 9-second runs will at least show where the stack was resonant and producing the peak thrust results without depoling it due to exceeding its Curie temperature.   And it appears that the peak thrust frequency is offset from the electrical and mechanical resonant frequencies of the stack due to the electrostrictive nonlinearities in the PZT material itself and the Carvin amplifier’s output verses frequency response.  A better solution would be to design a variable frequency negative feedback loop tied to the PZT Stack temperature that would automatically keep the drive frequency at or near the PZT-Stack resonant frequency with a tunable offset of XXX Hz.  Care to design us one?

"Why does the thrust noise trace trend up over the course of a run in a major way?"

I think that is due to thermal drift in the ARC-Lite torque pendulum due to the heat being generated in the test article and being dissipated through the torque penulum's aluminum structure and bearings via IR radiation, but you need to ask Woodward for his opinion on that one as well.

"If the unaveraged thrust signal was about 50 times what it currently is compared to the noise, there really wouldn't be any question."

OK, so you vote for a +/-50-to-100 micro-Newton output thrust using the same ARC-Lite test setup since it is currently producing ~1.3 micro-Newton, check.  As a reminder my Faraday shielded MLT consistently produced a reversable +/-1,000 to 5,000 micro-Newton while it was working...

Best,

Paul M.

Edit:  Corrected typos and units

Thanks for the detailed answer on the frequency sweep.

Absolutely, on the  1-5 mN response of your MLT being more than sufficient if the noise level is similar to Woodward's data above & the spurious sources is as clearly eliminated.

The issue is not the total level of thrust as discussed, but the signal to noise ratio. Since it is a new or unknown phenomenon that we are talking about, of course a higher standard is needed in order to be sure the cause is not a conventional source via an unknown coupling or pathway.

Offline 93143

  • Senior Member
  • *****
  • Posts: 3039
  • Liked: 292
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1401 on: 07/09/2011 12:10 AM »
Since it is a new or unknown phenomenon that we are talking about, of course a higher standard is needed in order to be sure the cause is not a conventional source via an unknown coupling or pathway.

And this is what I'm complaining about.  Why should a conventionally-understood phenomenon be subject to a relaxed standard of observational rigour?  How do you know the signal you get in that case isn't an artifact of poor experimental design?

If a certain level of "proof" is good enough to support an existing theory, why isn't it good enough to support a novel proposal?  Or, to put it the other way around, if it isn't good enough to support a novel proposal, why is it admissible in support of the consensus?

...

Sagan's quote makes some sense in a case where the preponderance of evidence is actually against a novel claim.  You've got a wall to scale there, though even there the standard of evidence should be the same on both sides.  But if the claim is merely not supported by existing theory and prior evidence, its unfamiliarity should be no bar to acceptance of valid evidence in support of it.
« Last Edit: 07/09/2011 04:28 AM by 93143 »

Offline IsaacKuo

  • Full Member
  • ****
  • Posts: 435
  • Liked: 1
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1402 on: 07/09/2011 12:53 AM »
And engine that gives you constant 1G like that is plenty for now,

As I understand it, the claimed accelerations are far smaller than 1 gee.  The accelerations in the claims so far are small enough that others attribute them to conventional forces.

If it's so easy to demonstrate 1 gee, then that should be demonstrated.  It would be impossible to dismiss.

Offline IsaacKuo

  • Full Member
  • ****
  • Posts: 435
  • Liked: 1
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1403 on: 07/09/2011 12:56 AM »
If transient mass fluctuations were being studied without the mention of applications to advanced propulsion, they would not even be regarded as an extraordinary claim.

Are there examples of mass fluctuations in mainstream physics?  I'm aware of various fringe claims of mass reduction, but as I understand mainstream physics, mass is conserved.

Offline 93143

  • Senior Member
  • *****
  • Posts: 3039
  • Liked: 292
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1404 on: 07/09/2011 12:56 AM »
If it's so easy to demonstrate 1 gee, then that should be demonstrated.  It would be impossible to dismiss.

It's not easy because it requires substantial scaling up in frequency, voltage, etc., as well as design refinements in the thrusters.  (It wouldn't hurt to come up with a dielectric that lasted longer than fifteen minutes under the current experimental conditions without annealing, either.)

These people are garage tinkerers, basically.  They have no budget.  But the projected scaling laws make the proponents think that such numbers as 1 N/W and a T/W of 10 or more are plausible with enough focused, well-funded engineering.  If they're right, it isn't just space travel that would undergo a paradigm shift...
« Last Edit: 07/10/2011 06:38 AM by 93143 »

Offline Star-Drive

  • Member
  • Full Member
  • ****
  • Posts: 829
  • TX/USA
  • Liked: 877
  • Likes Given: 9
Re: Propellantless Field Propulsion and application
« Reply #1405 on: 07/09/2011 04:36 AM »
If it's so easy to demonstrate 1 gee, then that should be demonstrated.  It would be impossible to dismiss.

It's not easy because it requires substantial scaling up in frequency, voltage, etc., as well as design refinements in the thrusters.  (It wouldn't hurt to come up with a dielectric that lasted longer than fifteen minutes under the current experimental conditions without annealing, either.)

These people are garage tinkerers, basically.  They have no budget.  But the projected scaling laws make the proponents think that such numbers as 1 N/W and a T/W of 10 or more are plausible with enough focused, well-funded engineering.  If they're right, it isn't just space travel that would undergo a paradigm shift...

Are there examples of mass fluctuations in mainstream physics?  I'm aware of various fringe claims of mass reduction, but as I understand mainstream physics, mass is conserved.

I believe this theory separates inertial mass from real or gravitating mass.  Not sure how it's supposed to result in wormholes, though perhaps I've misunderstood or misremembered something...

93143:

I'm going to append the abstract of Woodward's yet to be published Stargate paper below, and if you look at your e-mail in-basket...

Making Stargates: the Science of
Absurdly Benign Wormholes

James F. Woodward
Department of Physics
California State University, Fullerton, CA 92834
657-278-3596; jwoodward@fullerton.edu

Abstract. Stargates – extremely short throat “absurdly benign” wormholes enabling near instantaneous travel to arbitrarily remote locations in both space and time – have been a staple of science fiction now for decades. And the physical requirements for the production of such devices have been known since the work of Morris and Thorne in 1988. Their work has engendered a small, but significant literature on the issue of making stargates and warp drives. Morris and Thorne approached the issue of rapid spacetime transport by asking the question: what constraints do the laws of physics as we know them place on an “arbitrarily advanced culture” (AAC) in the design and implementation of stargates? Here we invert their question and ask: if “arbitrarily advanced aliens” (AAAs) have actually made stargates, what must be true of the laws of physics for them to have done so? The chief problem in making stargates is that they seem to require the assembly of a Jupiter mass of “exotic” matter concentrated in a thin structure with dimensions of a few tens of meters. Elementary arithmetic reveals that such structures would have a density of on the order of 1022 gm/cm3, that is, orders of magnitude higher than nuclear density. Not only does one have to achieve this stupendous density of negative mass matter, it must be done, presumably, only with the application of “low” energy electromagnetic fields. A few schemes that at least in principle purport to do this that have been proposed by capable physicists are discussed. And one that might actually work is examined in a little more detail.

Keywords: Stargates, Traversable Wormholes; Negative Matter; Time Machines; Semi-Classical Electron Models
PACS: 04.20Cv; 04.80Cc
Star-Drive

Offline sfuerst

  • Member
  • Posts: 35
  • Liked: 0
  • Likes Given: 0
Re: Propellantless Field Propulsion and application
« Reply #1406 on: 07/09/2011 05:22 AM »
Quote
I believe this theory separates inertial mass from real or gravitating mass.

Right, and this is the essence of the problem with M-E propulsion.  Unfortunately, it seems to be impossible to create distributions of gravitational mass/energy that would satisfy the interesting physics required to significantly alter the inertial mass.  Basically, some form of negative mass/energy is needed, and classically this is forbidden.

The real doozy is that if you could create negative energy matter then all sorts of exotic applications would be available.  No non-standard theory of inertia is required.

I think Woodward now realizes this, and hence his call out for new theory.  (The current theory is the scientific version of "begging the question".)

Quote
We keep trying, but I need a data point.  What kind of M-E data set will be required to tear you away from being "skeptical" and make you a believer in the M-E?  In other words, do we really need to float a self-contined, battery powered M-E test article into the confernce room under R-C control, while keeping it floating for XXX minutes to make you a believer?  Or can some subset of this M-E thruster performance level suffice?

What would make M-E interesting to other (theoretical) physicists is a theory of it that is consistent with other known physical phenomena.  The problem is that physicists have done all these pesky things called "experiments" that have tested large amounts of parameter space.  If you want to extend the currently accepted knowledge of how things work, you need to find a way to not be in conflict with all those results.  (Or at least show where those results were misinterpreted.)

Merely having an interesting experiment is not enough in this case.  Unfortunately, systematic error here seems to be orders of magnitude larger than the magnitude of the effect that is predicted.   Someone needs to accurately calculate what traditional physics predicts.  Remember, the real world isn't filled with spherical cows.  The PZ oscillator can have non-linearities.  There can be capacitance and inductance between separate parts of the apparatus giving forces much larger than those you wish to detect.  The sound from the PZ can resonate in strange ways with other components.  Small 1/c^2 effects can be much larger or as large as the force you wish to detect.  These things are not ignorable, even though you might like them to be.

Remember the Pioneer Anomaly.  There were many papers written about it assuming that it must mean that something was wrong with fundamental physics.  However, recently it was shown that "simple" anisotropic thermal radiation pressure was enough to explain everything about it.  Nature doesn't seem to be particularly amiable in allowing new improved descriptions of herself.

Of course, if you do manage to come up with a floating self-contained device.  It doesn't matter what the theory is (or if indeed any exists at all); as long as it is reproducible, it is useful.  Everyone is looking forward to their hoverboards and flying cars in 2015 after all...

Offline IsaacKuo

  • Full Member
  • ****
  • Posts: 435
  • Liked: 1
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1407 on: 07/09/2011 06:50 AM »
It's not easy because it requires substantial scaling up in frequency, voltage, etc., as well as design refinements in the thrusters.  (It wouldn't hurt to come up with a dielectric that lasted longer than fifteen minutes under the current experimental conditions without annealing, either.)

These people are garage tinkerers, basically.  They have no budget.  But the projected scaling laws make the proponents think that such numbers as 1 N/W and a T/W of 10 or more are plausible with enough focused, well-funded engineering.  If they're right, it isn't just space travel that would undergo a paradigm shift...

[...]

I believe this theory separates inertial mass from real or gravitating mass.  Not sure how it's supposed to result in wormholes, though perhaps I've misunderstood or misremembered something...

These really do sound like extraordinary fringe claims to me, that really do require extraordinary evidence.

Since I'm no theoretical physicist and thus can't form a properly informed assessment of my own, there's no way to convince me directly with some subtle disputed experimental results.  It would have to be indirectly by convincing the scientific community which I trust.

Until then, it has the same ring of untruth to me as various discredited claims such as the Dean drive, overunity devices, cold fusion, Joseph Newman's energy machine, and such.

Offline Cinder

  • Full Member
  • ****
  • Posts: 562
  • Liked: 51
  • Likes Given: 189
Re: Propellantless Field Propulsion and application
« Reply #1408 on: 07/09/2011 08:21 AM »
Extraordinary, unlike ... which un-extraordinary conjecture for the origins of inertia?
The pork must flow.

Offline IsaacKuo

  • Full Member
  • ****
  • Posts: 435
  • Liked: 1
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1409 on: 07/09/2011 10:48 AM »
Extraordinary, unlike ... which un-extraordinary conjecture for the origins of inertia?

According to you, what extraordinary claims result from the theory that inertial mass is the same as gravitational mass?

Like I said, you won't be able to directly convince me, because I know I lack sufficient comprehension of theoretical physics to properly evaluate the theory.  All I really know is that the mainstream scientific community finds the equivalence of inertial mass and gravitational mass to be uncontroversial and experimentally confirmed.  But I don't comprehend the subtleties of the theoretical ramifications or the fine subtleties of the experimental verification.

Offline Star-Drive

  • Member
  • Full Member
  • ****
  • Posts: 829
  • TX/USA
  • Liked: 877
  • Likes Given: 9
Re: Propellantless Field Propulsion and application
« Reply #1410 on: 07/09/2011 03:32 PM »
Quote
I believe this theory separates inertial mass from real or gravitating mass.

Right, and this is the essence of the problem with M-E propulsion.  Unfortunately, it seems to be impossible to create distributions of gravitational mass/energy that would satisfy the interesting physics required to significantly alter the inertial mass.  Basically, some form of negative mass/energy is needed, and classically this is forbidden.

The real doozy is that if you could create negative energy matter then all sorts of exotic applications would be available.  No non-standard theory of inertia is required.

I think Woodward now realizes this, and hence his call out for new theory.  (The current theory is the scientific version of "begging the question".)

Quote
We keep trying, but I need a data point.  What kind of M-E data set will be required to tear you away from being "skeptical" and make you a believer in the M-E?  In other words, do we really need to float a self-contined, battery powered M-E test article into the confernce room under R-C control, while keeping it floating for XXX minutes to make you a believer?  Or can some subset of this M-E thruster performance level suffice?

What would make M-E interesting to other (theoretical) physicists is a theory of it that is consistent with other known physical phenomena.  The problem is that physicists have done all these pesky things called "experiments" that have tested large amounts of parameter space.  If you want to extend the currently accepted knowledge of how things work, you need to find a way to not be in conflict with all those results.  (Or at least show where those results were misinterpreted.)

Merely having an interesting experiment is not enough in this case.  Unfortunately, systematic error here seems to be orders of magnitude larger than the magnitude of the effect that is predicted.   Someone needs to accurately calculate what traditional physics predicts.  Remember, the real world isn't filled with spherical cows.  The PZ oscillator can have non-linearities.  There can be capacitance and inductance between separate parts of the apparatus giving forces much larger than those you wish to detect.  The sound from the PZ can resonate in strange ways with other components.  Small 1/c^2 effects can be much larger or as large as the force you wish to detect.  These things are not ignorable, even though you might like them to be.

Remember the Pioneer Anomaly.  There were many papers written about it assuming that it must mean that something was wrong with fundamental physics.  However, recently it was shown that "simple" anisotropic thermal radiation pressure was enough to explain everything about it.  Nature doesn't seem to be particularly amiable in allowing new improved descriptions of herself.

Of course, if you do manage to come up with a floating self-contained device.  It doesn't matter what the theory is (or if indeed any exists at all); as long as it is reproducible, it is useful.  Everyone is looking forward to their hoverboards and flying cars in 2015 after all...

931423: “I believe this theory separates inertial mass from real or gravitating mass.”

Fuerst: “Right, and this is the essence of the problem with M-E propulsion.”

I’m going to append the beginning of Woodward’s “Flux Capacitors and the Origins of Inertia” paper’s “Appendix A”  that you already have below, as a reminder to you that the M-E does NOT violate Einstein’s Equivalence principle between gravitational and inertial effects, no matter what others on this NSF forum might think:

“To derive Equation (6) one considers a “test particle” (one with sufficiently small mass that it does not itself contributes directly to the field being investigated) in a universe of uniform matter density.  We act on the test particle by, say, attaching an electric charge to it and place in between the plates of a capacitor that can be a charged with suitable external apparatus.  That is, we accelerate the test particle by applying an external force.  The acceleration, via Newton’s third law, produces an inertial reaction force in the test particle that acts on the accelerating agent.  In view of the Machian nature of GRT and Sciama’s analysis of the origin of inertia, we see that the inertial reaction force produced in these circumstances is just the action of the gravitational field of the chiefly distant matter in the universe on the test particle as it is accelerated.  So we can write the field strength of the gravitational action on the test particle as the inertial reaction force it experiences divided by the mass of the test particle (since a field strength is a force per unit charge, the “charge” in this case being mass).  Actually, the standard form of field equations are expressed in terms of charge densities, so one has to do a volumetric division to get the force per unit mass expression into standard form.  There are two critically important points to take into account here.  The first is that the mass density that enters the field equation so constructed is the matter density of the test particle, not the matter density of the uniformly distributed cosmic matter that causes the inertial reaction force.  The second point is that in order to satisfy Lorentz invariance, this calculation is done using the four-vectors of relativistic spacetime, not the three-vectors of classical space and time.  Formally, we make two assumptions:

1. Inertial reaction forces in objects subjected to accelerations are produced by the interaction of the accelerated objects with a field – they are not the immediate consequence only of some inherent property of the object.  And from GRT and Sciama’s vector approximation argument, we know that the field in question is the gravitational field generated by the rest of the matter in the universe.

2. Any acceptable physical theory must be locally Lorentz-invariant; that is, in sufficiently small regions of spacetime special relativity theory (SRT) must obtain.”


If the M-E conjecture is Lorentz invariant and salutes SRT and it does on both counts, you know by definition that it observes the gravity/inertia Equivalence principle as well. 

Fuerst:  “Unfortunately, it seems to be impossible to create distributions of gravitational mass/energy that would satisfy the interesting physics required to significantly alter the inertial mass. Basically, some form of negative mass/energy is needed, and classically this is forbidden.”

Please READ and understand Woodward’s “Twists of Fate” (see attached), and Jim's latest Stargate paper before making such statements.  If you need a copy of Woodward's latest Stargate paper, just send him an e-mail requesting one.

Second point, Woodward was extending the olive branch to his ZPE critics in the hopes of forging a more coherent intellectual front for all parties interested in advancing the propulsion arts.  Funding agencies get confused when there is more than one viewpoint being expressed in the room.  Jim was NOT repudiating his M-E conjecture.

Lastly, agreed on the need for higher thusts in the M-E experimental realm so as to do away with the doubts surrounding measured forces in the micro-Newton range.  Milli-Newtons or even larger are a must have dependent on the summation magnitude of all known error sources.

Best,

Paul M. 
Star-Drive

Offline 93143

  • Senior Member
  • *****
  • Posts: 3039
  • Liked: 292
  • Likes Given: 1
Re: Propellantless Field Propulsion and application
« Reply #1411 on: 07/09/2011 03:36 PM »
Quote
I believe this theory separates inertial mass from real or gravitating mass.  Not sure how it's supposed to result in wormholes, though perhaps I've misunderstood or misremembered something...

I was actually fishing for data (a bit lazy of me, I guess).

Looks like I caught some...  thanks.

I did think I remembered some such distinction, but I couldn't remember what it was...
« Last Edit: 07/09/2011 03:39 PM by 93143 »

Offline kurt9

  • Member
  • Posts: 31
  • Liked: 0
  • Likes Given: 0
Re: Propellantless Field Propulsion and application
« Reply #1412 on: 07/09/2011 05:41 PM »

A demonstration around 1 millinewton would convince me its real.

GeeGee:

It should occur this fall with my MLT-2011 self-contained test article.

Kurt9:

1.0 milli-Newton under what circumstances?  My STAIF-2006 paper already demonstrated reversible MLT generated forces well over your 1.0 milli-Newton threshold requirement.

Best,

Paul M.

Your STAIF-2006 paper, is this the work you did with Andrew Palfreyman that includes the spreadsheet, a sample of which is in the presentation for AIAA at JSC in 2006?

Offline sfuerst

  • Member
  • Posts: 35
  • Liked: 0
  • Likes Given: 0
Re: Propellantless Field Propulsion and application
« Reply #1413 on: 07/09/2011 06:50 PM »
Quote
I’m going to append the beginning of Woodward’s “Flux Capacitors and the Origins of Inertia” paper’s “Appendix A”  that you already have below, as a reminder to you that the M-E does NOT violate Einstein’s Equivalence principle between gravitational and inertial effects, no matter what others on this NSF forum might think:

Paul, this isn't the problem.  The issues with M-E propulsion have nothing to do with the theory of inertia!  Any theory at all will do, so long as it couples to the gravitational mass/energy distribution.

The issue is one of engineering.  You simply cannot construct a gravitational mass/energy distribution that will have a time-varying monopole or dipole moment.  To do so requires you to be able to create negative gravitational mass/energy.

The current propulsion model tries to use a matter dipole... but it has a mistake where important terms are left out.  Add those terms, and the purported dipole disappears.

Physically, the lowest multipole order that is possible is the quadrapole.  This unfortunately lowers the magnitude of any effect enormously.  The need for a varying quadrapole moment is a very well known result.  Trying to ignore it doesn't do the M-E folks any favours.

Offline Sith

  • Full Member
  • *
  • Posts: 181
  • Bulgaria, EU
  • Liked: 0
  • Likes Given: 0
Re: Propellantless Field Propulsion and application
« Reply #1414 on: 07/09/2011 07:14 PM »
I like the last 2 paper of yours, thank you.

Offline cuddihy

  • Full Member
  • ****
  • Posts: 800
  • Liked: 143
  • Likes Given: 148
Re: Propellantless Field Propulsion and application
« Reply #1415 on: 07/09/2011 07:56 PM »

Physically, the lowest multipole order that is possible is the quadrapole.  This unfortunately lowers the magnitude of any effect enormously.  The need for a varying quadrapole moment is a very well known result.  Trying to ignore it doesn't do the M-E folks any favours.

Dr Fuerst,

Could you point to a reference that explains or at least expands on the above for us newbs to SRT/GRT?

thanks.
« Last Edit: 07/09/2011 07:56 PM by cuddihy »

Offline sfuerst

  • Member
  • Posts: 35
  • Liked: 0
  • Likes Given: 0
Re: Propellantless Field Propulsion and application
« Reply #1416 on: 07/09/2011 08:31 PM »
Quote
Could you point to a reference that explains or at least expands on the above for us newbs to SRT/GRT?

The beginning of Chapter 36 of MTW's Gravitation covers it in detail.  You can derive it in a couple of ways.  The simplest is from conservation of momentum and angular momentum.  Deeper insight comes from using topology and Brouwer's fixed point theorem to show the difference between the propagation of scalar, vector and tensor fields.

Scalar fields have monopole radiation.
Vector fields (electromagnetism) have dipole radiation.
Tensor fields (GR) have quadrupolar radiation. 

Offline cuddihy

  • Full Member
  • ****
  • Posts: 800
  • Liked: 143
  • Likes Given: 148
Re: Propellantless Field Propulsion and application
« Reply #1417 on: 07/09/2011 10:06 PM »
Quote
Could you point to a reference that explains or at least expands on the above for us newbs to SRT/GRT?

The beginning of Chapter 36 of MTW's Gravitation covers it in detail.  You can derive it in a couple of ways.  The simplest is from conservation of momentum and angular momentum.  Deeper insight comes from using topology and Brouwer's fixed point theorem to show the difference between the propagation of scalar, vector and tensor fields.

Scalar fields have monopole radiation.
Vector fields (electromagnetism) have dipole radiation.
Tensor fields (GR) have quadrupolar radiation. 

Thanks!

Holy Moly, the book's 38 years old & it still costs $55 bucks, used on Amazon.

I'm very interested, so I guess I'll have to bite the bullet.
« Last Edit: 07/09/2011 10:07 PM by cuddihy »

Offline sfuerst

  • Member
  • Posts: 35
  • Liked: 0
  • Likes Given: 0
Re: Propellantless Field Propulsion and application
« Reply #1418 on: 07/09/2011 10:45 PM »
There are other books that are possibly better.  The one by Wald comes to mind.  MTW was just handy at the moment.

Offline cuddihy

  • Full Member
  • ****
  • Posts: 800
  • Liked: 143
  • Likes Given: 148
Re: Propellantless Field Propulsion and application
« Reply #1419 on: 07/10/2011 03:01 AM »
Thanks

Tags: