Author Topic: Propellantless Field Propulsion and application  (Read 664768 times)

Offline blazotron

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Re: Propellantless Field Propulsion and application
« Reply #260 on: 04/20/2009 09:30 AM »
Quote
Quote
EM-Drive is not fake science. They have a WORKING prototype and are moving towards a flight test in 2009. www.emdrive.com. This uses actual physics and obeys all the convervation laws.

I am NOT impressed by this site.  It states that just like a laser ring gyro is a closed system and can measure rotation rate, this drive is a closed system that can produce force.  Newton and all have NO problem with a closed system measuring rotation rate.  No need to introduce Special Theory effects to explain this.  Explaining away the closed system problem by using the laser ring gyro as an analogy tells me these people are incorrect.

However I do hope I am wrong and they produce a really nice rocket engine someday.  I for one will not be investing my money in this technology.

Danny Deger

P.S.  Maybe there is some change of momentum of the photons that balances the change of momentum of the rocket.  This would make the device not violate the law of the conservation of momentum.

I took me a while to understand how it works. There is a basic property of a waveguide that describes how the group velocity of a wave changes as the size of the waveguide changes. For the em-drive it is this that creates the force imbalance on the end walls of the cavity. In terms of momentum, if there are two equal masses and the total momentum p=p1-p2 then p is non zero when the velocities of the particle colliding at each end of the waveguide differ. The slope of the walls of the cavity ensure the collisions with the walls along the length result in a nonlinear force ie: the differing group velocities along the length of the sloping cavity ensure the particles don't just bounce around inside the cavity canceling each others forces totally out. One uses the law of relativistic velocity addition to see that there is forward motion when the thruster is viewed by an outside observer (thus an open system).
To illustrate:
If one fires two opposing canons within a closed box the impact of the canonballs against the walls will cancel out to result in zero motion. If either the velocity or the mass of one of the balls changes en-route to the wall then the impacts will not cancel out and there will be motion. The trick then is to deal with the lost mass or velocity. It has to have gone somewhere.
From the point of view of momentum; The em-drive looks at the change in velocity whereas the woodward drive looks at the change in mass. The both deal with the imbalance in different ways. EM-drive uses the properties of waveguides and relativity whereas woodward's drive uses machian mass fluctuations and a rectifier.
When one accounts for the energy absorbed into the system to create the motion then one retains conversation of energy. Same for momentum.

So I think I understand. Took me a while but I think I'm there. And it is basic physics! It USES newton laws. It just needed a different perspective.





I don't have time right now to go through the whole "theory paper" at emdrive.com line-by-line to show where the analysis is flawed, but there are *numerous* problems with the physics.  Hopefully I will get around to this at some point in the reasonably near future.  From a first read through of the text, though, my reaction was to quote Pauli: "That's not right, it's not even wrong."

For starters, the very first section claims that the group velocity of a wave in a waveguide changes with diameter of the waveguide.  OK, fine.  Then it starts to go wrong...  The next statement claims that the difference in group velocity from one end to the other causes a force imbalance, resulting in a net thrust.  To support this, the author brings up the completely unrelated Lorentz force equation (which describes the force on a charged particle in an electromagnetic field).  In that equation, the velocity referred to is the velocity of the charged particle, yet the author suggests that we should substitute the group velocity of a wave instead to see that the force changes.  He claims that because this equation responds to a change in velocity in one way, another unrelated system should as well.

The next section asserts that the force of radiation on a reflective flat plate is just 2nhfA, which is the correct classical result based on momentum transfer of the incident photons in the light.  Then he states, completely without support, that the force imparted by a wave with group velocity vg is 2nhfA*(vg/c).  Nowhere in the text is it explained why we should be using the group velocity of the wave to calculate force.

In reality, it is the momentum of the photons that we care about, not the group velocity.  And guess what, photons always travel at c.  Always.  Regardless of what the group velocity of the wave is (which can in fact be different than c).  Now they may change energy by interacting with an object, and thus momentum and force, but that is never mentioned in the text (which is actually a major problem).

There are other, worse, problems with the text (relativistic frames of reference problems, relativistic simultaneity and timeline problems, unaccounted for changes in photon energy, etc.), but those will have to wait until I have more time to really dig in. 

Please also keep in mind that this is not a peer-reviewed paper.  It is just the unverified writing of one person.  It should give anyone reading it pause when they realize he includes only three references, and one of them is a college physics textbook...

Offline Spacenick

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Re: Propellantless Field Propulsion and application
« Reply #261 on: 04/20/2009 11:06 AM »
If and only if there is any truth to this science, then this type of drive would be more then revolutionary even if it had only a thrust of half a newton and even then it would be more then enough for use in human space flight in general. The thing people have to understand is that to go the moon for the most part of the trip we don't need a levitatiing device such a device would be nice but it is absolutely not needed.
If we could construct a tug that could carry 25 mt to lunar orbit from LEO within a timeframe of say 1 year, we would already have a huge advantage for manned spaceflight because we could build a salyut size lunar orbiting station for less money then sending a space shuttle to the ISS.
If that tug would be reusable and we could build say 25 of them, we could easyly be talking about a lunar base, and we could probably do it without any heavy lift launches only with current rockets.

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #262 on: 04/20/2009 01:43 PM »
Thanks for the explanation. Thrust efficiency is the term I was looking for.

A pico-newton is one trillionth of a newton.  It may be that the technology will scale as you hypothesise, but that's still a long way to go.

Is that level of thrust even enough to tweak a satellite's orbit?  And the current state is, roughly, a Carvin amp, at about 20 pounds, some kind of power supply, and some extra circuitry.  On the back of the ol' envelope, you'd roughly need a satellite of about 50-100 pounds to just demonstrate this in the real world. I'm sure something could be better modeled in software, but right now, the thrust efficiency is too low.

Further, the results haven't been replicated by a different lab, for reasons which sound vague.

I've read the article once, and now have blazotron's remarks to assist in my understanding.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #263 on: 04/20/2009 03:01 PM »
There's some other things worthy of note wrt emdrive.

About funding.  The Chinese have expressed interest in this technology, and seem willing to invest:

http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=1898

Also:

http://peakoil.com/energy-technology/chinese-say-they-re-building-impossible-space-drive-t45867.html

So there is some interest out there regarding this idea.  However, a Google search of the term:

CULLEN A.L. ‘Absolute Power Measurements at Microwave Frequencies’IEE Proceedings Vol 99 Part IV 1952 P.100

yields 45 English pages, which are related to either the two sites above or to variants on Roger Shawyer or SPR.  It's hard to find other points of view on this subject than Shawyer's.

Perhaps someone has a better online source to review this paper.  I think it is important to pursue becasue this reference is cited as the explanation for the derived equation "2nhfA*(vg/c)" which blazotron finds fault with in his analysis above.  With only a basic understanding of the math involved, it seems clear to me that group velocity does not have a place in a force calculation.

Perhaps this relationship can be better explained.
Sometimes I just flat out don't get it.

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #264 on: 04/20/2009 03:17 PM »
"By what mechanism is it reacting against the rest of the universe?  Why do other devices not react with the rest of the universe like this?  Why is this one special?  How can it instantaneously signal the rest of the universe to react?  Saying it is so doesn't make it so."

You sound like a physicist so let me appeal to you as if you are one.

The question you raise is the subject of all of Jim Woodward's theoretical writings found over the years in places like Foundations of Physics.  If you're a physicist with a real interest, you'll want to read the papers rather than take the word of a mindless philosopher like myself.  You can find some of the papers here:

http://physics.fullerton.edu/Woodward.html

However, to answer your question in short: the mechanism you are asking about is the ability to create a Mach Effect (M-E) otherwise known as a "mass fluctuation."  Jim's true genius apart from being a wonderfully gifted experimenter, is his bringing Mach's Principle together with Einstein's General Theory of Relativity, in order to show that under very specific conditions, the mass of a material will undergo a temporary fluctuation.  What we have is the entire, casually connected universe and its consequent "gravinertial field' as per Mach's Principle, can be used to generate a gravinertial flux into and out of the ceramic in question, causing its mass to fluctuate temporarily.

I'm sure that sounds like an outrageous claim to any physicist who has never studied Mach's Principle or read any of Jim Woodward's papers.  :-)  It's not so outrageous and this was all peer reviewed more than a decade ago.

So let me invite you to take a few minutes and read at least one of Jim's papers from over the years.

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #265 on: 04/20/2009 03:28 PM »
Thanks for the explanation. Thrust efficiency is the term I was looking for.

A pico-newton is one trillionth of a newton.  It may be that the technology will scale as you hypothesise, but that's still a long way to go.

Is that level of thrust even enough to tweak a satellite's orbit?  And the current state is, roughly, a Carvin amp, at about 20 pounds, some kind of power supply, and some extra circuitry.  On the back of the ol' envelope, you'd roughly need a satellite of about 50-100 pounds to just demonstrate this in the real world. I'm sure something could be better modeled in software, but right now, the thrust efficiency is too low.

Further, the results haven't been replicated by a different lab, for reasons which sound vague.

I've read the article once, and now have blazotron's remarks to assist in my understanding.

Well, we're not talking about pico-Newtons.  We're talking about uN or micro-Newtons which are also pretty small but not quite so small as you're talking.  :-)

Again about power system size.  Look, go on EBay and look for an ultrasonic carpet cleaner or an ultrasonic contact lens cleaner.  You'll find a $10 item that is handheld and weighs about 1/4 to 1/2 pound. The power supply in these items would work well to power a future MLT or UFG and the amount of thrust it would produce depends upon the thrust efficiency of the thruster.  But in short, though these power systems need to be carefully impedance matched, just as with any power system, they are not large, heavy etc.  As I said, one has been built and run for a 1 Mhz thruster that was half the size of a Coke can.  The power systems and supplies do not have to be large and heavy, but useful thrusters do need to have a certain level of thrust efficiency.

This work has been done in at least two labs, Jim Woodward's lab at CS Fullerton and Paul March's lab in Houston. I would love to see more replications happen very soon.  Perhaps the rotator, since it is such an inexpensive experiment to do; will get some more people interested.

Offline Star-Drive

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Re: Propellantless Field Propulsion and application
« Reply #266 on: 04/20/2009 08:07 PM »
Folks:

Let me clarify a few things that G/I Thruster has said recently.  I know of at least nine other attempts at replicating Jim's Woodward mass fluctuation conjecture, his unidirectional force generators (UFG) or the Mach-Lorentz Thruster (MLT) devices.  I’ll list them below in the year they were first published:

1.   Hector Brito’s ~1996 self contained battery operated MLT like device running at ~40 kHz that demonstrated ~1.0 micro-Newton level thrusts based on his E&M Slepian approach to this propellantless thruster business. 

2.  Andrew Palfreyman’s 1990’s UFG experiment reporting null results.

3.  Woodward’s 1997-9 graduate student Tom Mahood with his ~50 kHz UFG torque pendulum in a vacuum experiments that demonstrated thrust levels on the order of 0.10 to 1.00 micro-Newton.

4.  John Mckeever’s Oak-Ridge lab team’s 2000 MLT replication that reported thrust signatures  that were attributed to thermal effects.

5.  Paul March’s 2004 & 2005 MLT data running at 2.2 and 3.8 MHz reported up to 5.0 milli-Newton results.

6.  John Cramer’s 2005 thru 2007, 220 Hz Machian Guitar mass fluctuation experiment which resulted in an ambiguous results before their BPP money ran out.

7.  Nembo Buldrini’s 2006, 50 kHz and 2.0 MHz ambiguous or null results.

8.  John Strader’s 2006, ~400 kHz MLT experiments that reported null results.

9.  Duncan Cumming’s 2007 self-contained coke can MLT running at ~400 kHz reported null results.

10.  Jim Woodward’s latest 2008/2009 M-E rotary proof of principle tests that have clearly demonstrated above the noise 2-omega M-E like mass fluctuations signatures.


Looking back over this list I can appreciate why a lot of folks view Woodward’s M-E conjecture in the same light as they do the “Cold Fusion” conjecture, but in a similar way, I believe that Woodward’s M-E conjecture will be validated in a similar manner as the cold fusion story has unfolded over the last twenty years.  (See attached CBS 60 Minutes story on the resurrection of cold fusion that aired yesterday (04-19-2009).  Why do I think this way?  Because of the extreme difficulty in getting the phase relations between the acoustical and electrical drive signals in these M-E based devices to constructively interfere with each other instead of killing each other off.   In others words there are thousands of ways to build and operate these devices where they won’t work, but there is only a few ways to build and operate them where they will work.  Hector Brito, Tom Mahood and I are the only folks that I know of who happened to luck into the right combination of ingredients to make it play with my and Jim Woodward’s Mach-2MHz MLT experiment providing the largest thrust signatures to date.

BTW, Woodward’s lowest vacuum pressure ever achieved in his lab was on the order of ~2x10^-3 Torr and not 1x10^-6 Torr as reported by G/I thruster.  Considering that Woodward has never pumped his Plexiglas vacuum chambers with anything more than a standard Welch vacuum roughing pump, that is hardly surprising.  However, ~2x10^-3 Torr pressure is quite sufficient to kill off 99.99% of the ion wind issues that could contaminate Woodward’s MLT results, even when his MLTs were only producing a few micro-Newton. 
Star-Drive

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #267 on: 04/20/2009 09:19 PM »
Yes well, memory fades.  I checked and you're right Paul, Jim's vacuum is E-3T.  But your memory isn't so good either!  I think John ran at 200 khz and Duncan at 1 mhz.  :-)  Also, since Hector was not even looking at Woodward's theory, and John was trying to run self induced currents, you wouldn't necessarily put them on the list.

And certainly you missed all of Jim's work until 2008.  Oooops. . .
« Last Edit: 04/20/2009 10:48 PM by GI-Thruster »

Offline Star-Drive

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Re: Propellantless Field Propulsion and application
« Reply #268 on: 04/21/2009 04:19 AM »
G/I Thruster:

Dr. Cumming ran two different experiments with the first one running at 430 kHz and the second one in self contained Coke can version at ~1.0 MHz, so I was wrong on the second one and correct on the first.  However, both of these tests were still null results. 

As to Hector Brito's Slepian work, Hector may not have based his theoretical approach on Dr. Woodward's M-E conjecture, but the end results created near identical experimetnal ExB designs when compared to Jim's MLTs, so if it works or doesn't, IMO it still has a bearing on this verification list.

BTW, I didn't include the majority of Dr. Woodward's experiments during this time period because I was trying to list independent verifications by other experimenters and I only included Jim’s latest 2008/9 M-E proof of principle rotary work because of its importance and since nobody has tried a replication of it yet. 


Star-Drive

Offline D_Dom

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Re: Propellantless Field Propulsion and application
« Reply #269 on: 04/21/2009 05:59 AM »
I have been thinking about small scale technology demonstrators. Comments earlier about ultrasonic contact lens cleaner reminded me of a toothbrush I bought recently. Manufacturer claims 1.6 Mhz for over twenty minutes cumulative between charges. Amazingly small and light, I wonder how far it will fly after I modify it into a model rocket. I have had great fun launching 35mm film canisters from my hand after filling with a little water and half an alka-seltzer tablet. Makes a wonderful demonstration for grade school kids.
Space is not merely a matter of life or death, it is considerably more important than that!

Offline blazotron

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Re: Propellantless Field Propulsion and application
« Reply #270 on: 04/21/2009 08:26 AM »
"By what mechanism is it reacting against the rest of the universe?  Why do other devices not react with the rest of the universe like this?  Why is this one special?  How can it instantaneously signal the rest of the universe to react?  Saying it is so doesn't make it so."

You sound like a physicist so let me appeal to you as if you are one.

The question you raise is the subject of all of Jim Woodward's theoretical writings found over the years in places like Foundations of Physics.  If you're a physicist with a real interest, you'll want to read the papers rather than take the word of a mindless philosopher like myself.  You can find some of the papers here:

http://physics.fullerton.edu/Woodward.html

However, to answer your question in short: the mechanism you are asking about is the ability to create a Mach Effect (M-E) otherwise known as a "mass fluctuation."  Jim's true genius apart from being a wonderfully gifted experimenter, is his bringing Mach's Principle together with Einstein's General Theory of Relativity, in order to show that under very specific conditions, the mass of a material will undergo a temporary fluctuation.  What we have is the entire, casually connected universe and its consequent "gravinertial field' as per Mach's Principle, can be used to generate a gravinertial flux into and out of the ceramic in question, causing its mass to fluctuate temporarily.

I'm sure that sounds like an outrageous claim to any physicist who has never studied Mach's Principle or read any of Jim Woodward's papers.  :-)  It's not so outrageous and this was all peer reviewed more than a decade ago.

So let me invite you to take a few minutes and read at least one of Jim's papers from over the years.

I'm an engineer, but I have a strong background in physics, so I can hold my own until the math gets really gnarly.  I have not looked at any of Woodward's papers before, so I'll gladly do that when I get a chance.  Unfortunately, I am leaving in a few days for a 3 week stint at a caving expedition to Mexico (http://www.usdct.org if you are interested--and no I am not insane enough to dive in-cave), so it will be a while before I can sit down and really absorb them. 

[edited for typo]
« Last Edit: 12/02/2009 08:51 AM by blazotron »

Offline blazotron

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Re: Propellantless Field Propulsion and application
« Reply #271 on: 04/21/2009 08:47 AM »
Folks:

Let me clarify a few things that G/I Thruster has said recently.  I know of at least nine other attempts at replicating Jim's Woodward mass fluctuation conjecture, his unidirectional force generators (UFG) or the Mach-Lorentz Thruster (MLT) devices.  I’ll list them below in the year they were first published:

1.   Hector Brito’s ~1996 self contained battery operated MLT like device running at ~40 kHz that demonstrated ~1.0 micro-Newton level thrusts based on his E&M Slepian approach to this propellantless thruster business. 

2.  Andrew Palfreyman’s 1990’s UFG experiment reporting null results.

3.  Woodward’s 1997-9 graduate student Tom Mahood with his ~50 kHz UFG torque pendulum in a vacuum experiments that demonstrated thrust levels on the order of 0.10 to 1.00 micro-Newton.

4.  John Mckeever’s Oak-Ridge lab team’s 2000 MLT replication that reported thrust signatures  that were attributed to thermal effects.

5.  Paul March’s 2004 & 2005 MLT data running at 2.2 and 3.8 MHz reported up to 5.0 milli-Newton results.

6.  John Cramer’s 2005 thru 2007, 220 Hz Machian Guitar mass fluctuation experiment which resulted in an ambiguous results before their BPP money ran out.

7.  Nembo Buldrini’s 2006, 50 kHz and 2.0 MHz ambiguous or null results.

8.  John Strader’s 2006, ~400 kHz MLT experiments that reported null results.

9.  Duncan Cumming’s 2007 self-contained coke can MLT running at ~400 kHz reported null results.

10.  Jim Woodward’s latest 2008/2009 M-E rotary proof of principle tests that have clearly demonstrated above the noise 2-omega M-E like mass fluctuations signatures.


Looking back over this list I can appreciate why a lot of folks view Woodward’s M-E conjecture in the same light as they do the “Cold Fusion” conjecture, but in a similar way, I believe that Woodward’s M-E conjecture will be validated in a similar manner as the cold fusion story has unfolded over the last twenty years.  (See attached CBS 60 Minutes story on the resurrection of cold fusion that aired yesterday (04-19-2009).  Why do I think this way?  Because of the extreme difficulty in getting the phase relations between the acoustical and electrical drive signals in these M-E based devices to constructively interfere with each other instead of killing each other off.   In others words there are thousands of ways to build and operate these devices where they won’t work, but there is only a few ways to build and operate them where they will work.  Hector Brito, Tom Mahood and I are the only folks that I know of who happened to luck into the right combination of ingredients to make it play with my and Jim Woodward’s Mach-2MHz MLT experiment providing the largest thrust signatures to date.

BTW, Woodward’s lowest vacuum pressure ever achieved in his lab was on the order of ~2x10^-3 Torr and not 1x10^-6 Torr as reported by G/I thruster.  Considering that Woodward has never pumped his Plexiglas vacuum chambers with anything more than a standard Welch vacuum roughing pump, that is hardly surprising.  However, ~2x10^-3 Torr pressure is quite sufficient to kill off 99.99% of the ion wind issues that could contaminate Woodward’s MLT results, even when his MLTs were only producing a few micro-Newton. 


Star-Drive:

Thank you for the nice summary of experimental work.

I wanted to comment that while 2E-3 Torr may be plenty to kill off most of the ion effects, it places the pressure almost at the peak of the Crookes Radiometer effect:
http://en.wikipedia.org/wiki/Crookes_radiometer

Offline Star-Drive

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Re: Propellantless Field Propulsion and application
« Reply #272 on: 04/21/2009 12:18 PM »
Blazotron:

This independent M-E conjecture experimental verification list is not exhaustive, but it does cover the major replication efforts I'm familiar with. 

As to the Crookes Radiometer effect, that is somewhat problematic at 2x10^3 Torr and it is one reason I keep harping on going down to at least 1x10^-6 Torr or even 1x10^-7 Torr where the vacuum relay folks hang their hats.  However, Woodward did mitigate the Radiometer effect and others like it by potting all his latter vacuum test articles in steel Faraday shields that would have killed off any such thrust effects.  In other words what he is reporting is most likely something that is NOT due to mundane effects.  He is too good an experimeter to get caught in that trap more than once.
Star-Drive

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #273 on: 04/21/2009 04:43 PM »
Folks:

Let me clarify a few things that G/I Thruster has said recently.  I know of at least nine other attempts at replicating Jim's Woodward mass fluctuation conjecture, his unidirectional force generators (UFG) or the Mach-Lorentz Thruster (MLT) devices.  I’ll list them below in the year they were first published:

1.   Hector Brito’s ~1996 self contained battery operated MLT like device running at ~40 kHz that demonstrated ~1.0 micro-Newton level thrusts based on his E&M Slepian approach to this propellantless thruster business. 

2.  Andrew Palfreyman’s 1990’s UFG experiment reporting null results.

3.  Woodward’s 1997-9 graduate student Tom Mahood with his ~50 kHz UFG torque pendulum in a vacuum experiments that demonstrated thrust levels on the order of 0.10 to 1.00 micro-Newton.

4.  John Mckeever’s Oak-Ridge lab team’s 2000 MLT replication that reported thrust signatures  that were attributed to thermal effects.

5.  Paul March’s 2004 & 2005 MLT data running at 2.2 and 3.8 MHz reported up to 5.0 milli-Newton results.

6.  John Cramer’s 2005 thru 2007, 220 Hz Machian Guitar mass fluctuation experiment which resulted in an ambiguous results before their BPP money ran out.

7.  Nembo Buldrini’s 2006, 50 kHz and 2.0 MHz ambiguous or null results.

8.  John Strader’s 2006, ~400 kHz MLT experiments that reported null results.

9.  Duncan Cumming’s 2007 self-contained coke can MLT running at ~400 kHz reported null results.

10.  Jim Woodward’s latest 2008/2009 M-E rotary proof of principle tests that have clearly demonstrated above the noise 2-omega M-E like mass fluctuations signatures.


Looking back over this list I can appreciate why a lot of folks view Woodward’s M-E conjecture in the same light as they do the “Cold Fusion” conjecture, but in a similar way, I believe that Woodward’s M-E conjecture will be validated in a similar manner as the cold fusion story has unfolded over the last twenty years.  (See attached CBS 60 Minutes story on the resurrection of cold fusion that aired yesterday (04-19-2009).  Why do I think this way?  Because of the extreme difficulty in getting the phase relations between the acoustical and electrical drive signals in these M-E based devices to constructively interfere with each other instead of killing each other off.   In others words there are thousands of ways to build and operate these devices where they won’t work, but there is only a few ways to build and operate them where they will work.  Hector Brito, Tom Mahood and I are the only folks that I know of who happened to luck into the right combination of ingredients to make it play with my and Jim Woodward’s Mach-2MHz MLT experiment providing the largest thrust signatures to date.

BTW, Woodward’s lowest vacuum pressure ever achieved in his lab was on the order of ~2x10^-3 Torr and not 1x10^-6 Torr as reported by G/I thruster.  Considering that Woodward has never pumped his Plexiglas vacuum chambers with anything more than a standard Welch vacuum roughing pump, that is hardly surprising.  However, ~2x10^-3 Torr pressure is quite sufficient to kill off 99.99% of the ion wind issues that could contaminate Woodward’s MLT results, even when his MLTs were only producing a few micro-Newton. 


Star-Drive:

Thank you for the nice summary of experimental work.

I wanted to comment that while 2E-3 Torr may be plenty to kill off most of the ion effects, it places the pressure almost at the peak of the Crookes Radiometer effect:
http://en.wikipedia.org/wiki/Crookes_radiometer

That's a very astute observation.  However, Woodward's controls care after even that issue.

The point of vacuum is that if there is any ion wind or thermal contamination of the data, this will be apparent from even E-1T.  If you run a test item and get a specific thrust result, then run it at E-1T and E-2T and get the same result, then you can guess you'll get the same at E-3T and you're justified in accepting there is no ion wind or thermal forms of spurious.  Another way we know we are not seeing something like Crooke's is that the thrusters are reversible.  For instance, an MLT will produce no thrust when its e and b fields are phased at 0 or 180 degrees.  They produce thrust in one direction at 90* and thrust in the opposite direction at 270*.  That's not something that can be explained by reference to radiometers.

Cool that you're caving.  Too bad you're not doing the diving.  Did someone hire you to carry out the em. . .you know. . .stuff you can't leave behind?  Or are you paying someone else to carry their trash?  :-)

Offline JohnFornaro

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Re: Propellantless Field Propulsion and application
« Reply #274 on: 04/21/2009 07:19 PM »
Sorry about the misunderstanding between pico- and micro-.  I got pico-from stardrives post on 04-19-09.

Backing up to the Warpstar craft.  It is not actually designed, it is thought to be designed.  Without getting too hung up semantically, it is not designed at the same level of detail that Ares is, or even Jupiter Direct.  Therefore I think it’s a bit premature to be speaking of it as if it were designed to reach the Moon in a couple of hours, whereas the folks designing Ares seem to have more credibility in saying that their craft is designed to reach the Moon in a couple of days.

Again, a semantic bit of hand waving.  I’m not satisfied with the idea that science can’t “prove” any thing, because what science does is provide “compelling evidence”.  Let me rephrase my remarks to suggest that Jim Woodward has not offered sufficient “compelling evidence” so that there is little room for debate as to the outcome of his experiments.

But also about the power requirements.  There’s a post above that mentions a Carvin 2kw amp.  This thing has got to weigh twenty pounds or more, and be supplied by 110V current, right?  Please explain how a 2kw power supply provides only micro-newtons of force.  It would seem that an electric motor is more efficient.

But more about the math and my reading of IAC- 08 – C4.4.7.  which I’ll call “The Theory Paper”.

Group velocity is the speed with which the modulation of the wave propagates through space.  It is not the speed which any particles propagate. It is here that the paper falls apart for me, and is precisely the point in the cannonball analogy above where the analogy falls apart.  All of the cannonballs’ momentii (if that’s the word) will cancel out, unless the mass of a cannonball changes.  Then the analogy can propel itself forward.  But there’s no explanation of what it is that changes about the cannonballs to provide momentum.

Group velocity is dw/dk, where w is the wave’s angular frequency and k is the wave number.  I don’t see how this affects momentum.

In blazotron’s analysis of the theory paper, he states: “Then [Shawyer] states, completely without support, that the force imparted by a wave with group velocity vg is 2nhfA*(vg/c).  Nowhere in the text is it explained why we should be using the group velocity of the wave to calculate force.”  I think blazeotron is somewhat incorrect in stating where in the text is this explained.  The author alludes to:

CULLEN A.L. ‘Absolute Power Measurements at Microwave Frequencies’ IEE proceedings Vol 99 Part IV 1952

as explaining where he gets the above derivation.  But this is not an actual explanation, so semantically I guess, blazotron is right!

Please post Cullen’s paper on this forum.  A simple web search will not provide this paper online.
Sometimes I just flat out don't get it.

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #275 on: 04/21/2009 08:09 PM »
"But also about the power requirements.  There’s a post above that mentions a Carvin 2kw amp.  This thing has got to weigh twenty pounds or more, and be supplied by 110V current, right?  Please explain how a 2kw power supply provides only micro-newtons of force.  It would seem that an electric motor is more efficient."

Em, yeah.  An electric motor would be more efficient than the test articles to date if indeed it had something in space to actually push off of--which it would not--which is why till the foreseeable future we're stuck with rockets.

Look, yer joshin' me right?  How many times do you need an answer to the same question?

To the best of my knowledge, the most power ever dissipated in any of the test articles is about 400 watts.  You can get that from a single battery the size of a wine cork.

Look, if you want to form a meaningful comparison between M-E thrusters and existing tech, perhaps we can fumble through one though I don't see this as useful yet.  But lets have at.

I don't know how many watts Paul March used on his MTL but lets say he used 250.  He got 5 mN thrust.  If that's so, then the same thruster could be bundled with three others and you'd have 20 mN thrust, the same as the max thrust of the ion thrusters on the GOCE.  Now I don't know what the power requirements are for the GOCE thrusters but I do know they require 40 kg of Xenon for a 2 year mission, plus the power system.  So if your MLT bundle is anywhere in the ballpark of 40 kg, and the power requirements are anything near the same (1KW), you know that the MLT is competitive with some of the best ion tech out there.

Anyone know what GOCE's thrusters require?

But again let me state in no uncertain terms that I am NOT SAYING this is a useful comparison.  Before we could talk about competing with things like ion, we'd have to solve issues like the ceramic ageing issue and we haven't even begun to look into that yet.  We are not working on prototyping.  We're working on pure research.
« Last Edit: 04/21/2009 08:39 PM by GI-Thruster »

Offline Star-Drive

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Re: Propellantless Field Propulsion and application
« Reply #276 on: 04/21/2009 10:22 PM »

"But also about the power requirements.  There’s a post above that mentions a Carvin 2kw amp.  This thing has got to weigh twenty pounds or more, and be supplied by 110V current, right?  Please explain how a 2kw power supply provides only micro-newtons of force.  It would seem that an electric motor is more efficient."

Em, yeah.  An electric motor would be more efficient than the test articles to date if indeed it had something in space to actually push off of--which it would not--which is why till the foreseeable future we're stuck with rockets.
.
(snip)
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I don't know how many watts Paul March used on his MTL but lets say he used 250.  He got 5 mN thrust.  If that's so, then the same thruster could be bundled with three others and you'd have 20 mN thrust, the same as the max thrust of the ion thrusters on the GOCE.  Now I don't know what the power requirements are for the GOCE thrusters but I do know they require 40 kg of Xenon for a 2 year mission, plus the power system.  So if your MLT bundle is anywhere in the ballpark of 40 kg, and the power requirements are anything near the same (1KW), you know that the MLT is competitive with some of the best ion tech out there.

Anyone know what GOCE's thrusters require?

But again let me state in no uncertain terms that I am NOT SAYING this is a useful comparison.  Before we could talk about competing with things like ion, we'd have to solve issues like the ceramic ageing issue and we haven't even begun to look into that yet.  We are not working on prototyping.  We're working on pure research.

Guys:

The Mach-2MHz that produced a peak thrust of ~5.0 milli-Newton was absorbing approximately 7.0 Watts from the 3.8 MHz transmitter it was attached to at the time.  In other words its efficiency was ~0.714 mill-Newton/Watt or its Newton/Watt efficiency was 0.00071 Newton/Watt.

If you don't like that performance metric, how about the equivalent specific impulse (Isp-e) approach that utilizes the E=m*c^2 energy to mass equivalency equation which indicates that the Mach-2MHz had an Isp-e of ~1.0 tera-seconds, see the attached derivation.  This level of performance is currently very competitive with a number of ion rockets on an Isp basis, but as noted by G/I Thruster, its lifetime is only measured in minutes, instead of years required by current satellite customers, and its thrust level needs to be brought up to the ~100 milli-Newton range to be competitive with the likes of NASA's Deep Space-1.
« Last Edit: 04/21/2009 10:24 PM by Star-Drive »
Star-Drive

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #277 on: 04/21/2009 11:19 PM »
Thanks Paul but if you could help us out here, I honestly believe John's concern is better answered not by looking at Isp and mass energy equivalence, but by comparison to something like GOCE.  If your test article only dissipated 7 watts, then using it as an example, we can say that 4 of them would provide the same thrust as the GOCE system.  GOCE is covered in PV cells and it's a safe bet I think that the thrusters need a lot more than 28 watts.  So if we ignore the ceramic die-off issue, and toss in some spit-ball figures for MLT thermal stability subsystems, we can still assert that your experiment shows performance well in advance of this new satellite station keeping system.  An MLT with no thrust efficiency improvement over what you saw in the lab would be vastly more capable than this cutting-edge system being flown by ESA.

Offline Jim

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Re: Propellantless Field Propulsion and application
« Reply #278 on: 04/21/2009 11:23 PM »
cutting-edge system being flown by ESA.

What cutting-edge system?  Ion propulsion is not new.

Offline GI-Thruster

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Re: Propellantless Field Propulsion and application
« Reply #279 on: 04/21/2009 11:38 PM »
cutting-edge system being flown by ESA.

What cutting-edge system?  Ion propulsion is not new.

Ion is not new.  It's had millions in development for more than 4 decades.  But as the text says, no normal propulsion system can do what it does.  GOCE itself is new.  Very new.  A good standard to measure against when talking about satellite station-keeping:

http://www.esa.int/SPECIALS/GOCE/SEMSZCEH1TF_0.html

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