Author Topic: EM Drive Developments Thread 1  (Read 762620 times)

Offline Stormbringer

  • Full Member
  • ****
  • Posts: 1285
  • Liked: 222
  • Likes Given: 80
Re: EM Drive Developments
« Reply #200 on: 08/06/2014 04:20 AM »
without knowledge; such a thing may be equivalent to shouting "Swamp Gas!" at every unknown areal phenomenon though. it may be that it's not Swamp Gas; It Could be Venus! or a illumination flare. a person that reflexively hollers swamp gas isn't advancing science. whether it really is a LGM or if it turns out to be any explanation other than swamp gas. the swamp gas camp does a diservice if it is really Venus and they didn't bother to check things out. the real thing remains unknown if the debunking is via the critic's own bunkum.
When antigravity is outlawed only outlaws will have antigravity.

Offline ChrisWilson68

  • Senior Member
  • *****
  • Posts: 3519
  • Sunnyvale, CA
  • Liked: 2075
  • Likes Given: 2412
Re: EM Drive Developments
« Reply #201 on: 08/06/2014 04:28 AM »
I was replying to an unqualified statement with a qualified statement.  The unqualified statement I was replying to said that claiming flaws does not advance science.  My reply was qualified, to point out that in some cases it does.

Offline Stormbringer

  • Full Member
  • ****
  • Posts: 1285
  • Liked: 222
  • Likes Given: 80
Re: EM Drive Developments
« Reply #202 on: 08/06/2014 04:33 AM »
I see. I missed that. My mistake.
When antigravity is outlawed only outlaws will have antigravity.

Offline aero

  • Senior Member
  • *****
  • Posts: 2736
  • 92129
  • Liked: 704
  • Likes Given: 235
Re: EM Drive Developments
« Reply #203 on: 08/06/2014 04:37 AM »
Quote
The proper question to ask of Occam's razor whether it's more likely that three small groups made mistakes in their test setups that gave them the results they desperately wished to see, or that tens of thousands of physicists working over decades completely failed to find an effect that is easy to produce on a variety of different devices that are simple to make.

No. The proper question to ask of Occam's razor whether it's more likely some large number of the tens of thousands of physicists working over decades are righteously offended after completely failing to investigate an unknown effect that is easy to produce on a variety of different devices that are simple to make after one man stumbled across that effect and three small groups reproduced it, or if the effect could in fact be real.

Retired, working interesting problems

Offline aero

  • Senior Member
  • *****
  • Posts: 2736
  • 92129
  • Liked: 704
  • Likes Given: 235
Re: EM Drive Developments
« Reply #204 on: 08/06/2014 04:54 AM »
Quote
If there is a good reason to suspect an experimental flaw, pointing out that reason and spreading the idea about that flaw does absolutely advance scientific knowledge.

While that is true, it is also true that the main reason to suspect an experimental flaw is that posters don't understand how the device could work as claimed. Now this may be a good reason, but I don't think so. No one knows everything. I have suggested that a better way to advance science would be to propose a germ of an idea that could maybe explain the phenomena for further development by the crowd. Crowd sourced science.

Of course it is hard to propose an idea because doing so sets the proposer up as the butt of the criticism that is currently aimed at the experimenters. What sane person would eagerly step into that line of fire? In order for crowd sourced science to work, the thread would need a strong and heavy handed moderator, with name calling an absolute "no-no."
« Last Edit: 08/06/2014 04:57 AM by aero »
Retired, working interesting problems

Offline aero

  • Senior Member
  • *****
  • Posts: 2736
  • 92129
  • Liked: 704
  • Likes Given: 235
Re: EM Drive Developments
« Reply #205 on: 08/06/2014 07:54 AM »
I just finished reviewing the full AIAA paper that NASA submitted. There are several very interesting details once you get into the meat of it. One thing in particular was this:

Quote
There appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be evaluated using numerous COMSOL® iterations to arrive at a viable thruster solution. We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust.

I don't know what it means, but it says that they took out one little piece and that little piece proved to be critical to producing thrust.

Of course I guess that little piece could have been central to the "experimental error."

What is a dielectric RF resonator and what is it used for?

Another point of interest is that that COMSOL® computer program they have seems to predict the thrust produced to quite high fidelity. I guess the computer program must have a built in "experimental error" bias.

Read the paper people, quit fooling yourselves with second hand information.
Retired, working interesting problems

Offline MP99

Re: EM Drive Developments
« Reply #206 on: 08/06/2014 09:17 AM »



This discovery came about because Shawyer was trying to explain the thrust generated by the microwave transmitters on satellites which exceeded what was expected and required additional fuel to correct.

This would really make an interesting subject to read or a comparison point to read up on.
who you be able to supply a link or a paper?

I have spent about 5 hours and have been unable to find it again.  Google is worthless because any keywords I can think of only find hundreds of news articles about the recent NASA experiment.  It was a mention in a forum, it wasn't an official paper.  Perhaps someone with better google-fu can find it.

Sounds like this may be of some use, then, to weed out the new news:-

http://www.quora.com/Can-I-restrict-Google-searches-by-a-date-range

Cheers, Martin

Offline Darkseraph

  • Full Member
  • ****
  • Posts: 446
  • Liked: 165
  • Likes Given: 84
Re: EM Drive Developments
« Reply #207 on: 08/06/2014 09:33 AM »
I suppose the question to ask next is, Has NASA finally invented a thruster that finally defies Betterridge's Law of Headlines?


Color me skeptical after Flesichmann-Ponns, OPERA...

Great if it was true (or terrifying considering the inevitable military applications) but I will wait a while this blows over and see if it sticks.

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline JohnFornaro

  • Not an expert
  • Senior Member
  • *****
  • Posts: 9162
  • Delta-t is the salient metric.
  • Planet Eaarth
    • Design / Program Associates
  • Liked: 610
  • Likes Given: 314
Re: EM Drive Developments
« Reply #208 on: 08/06/2014 01:55 PM »
I step into this debate with trepidation. My perspective is that neither proponent has developed a successful characterisation of any effect...

Pretty much Bingo, I'd say.  Still, I think that NASA is correct to offer them the opportunity to test.  From:

http://ntrs.nasa.gov/search.jsp?R=20140006052

Quote
Financial Sponsor: NASA Johnson Space Center; Houston, TX, United States

I imagine that NASA spent an appropriate sum on this testing.  There has to be some official acknowledgement that these people are attempting to validate a theory, and they do need a place to set up the experiment.  I also noted the results for the null article.

The commentary on the intertubes site that I read is, well, inspiring and informative:

This is strangely arousing.

Sabina's yoga class is at 5:30 this afternoon.  Sadly, I guess, neither strange nor arousing, nor dismissive of the laws of physics.  You can't get into a pose that you can't get into.

Quote from: Steve Kelsey
A rocket motor utilises the shape of the nozzle to convert chemical energy to a directed force, which we call thrust. Is it possible that all that happening here is microwave energy is converted to thrust by the shape of the chamber?

They never photograph the "other end" of the "nozzle".  I do not believe that it is open.  No matter is expected to be expelled from the thought to be open end of the nozzle.  The device is expected to move without expelling matter.

In essence, they claim to be able to convert electricity to microwaves to forward momentum.

Image found at:

http://www.scribd.com/doc/235868930/Anomalous-Thrust-Production-from-an-RF-Test-Device-Measured-on-a-Low-Thrust-Torsion-Pendulum
« Last Edit: 08/06/2014 02:00 PM by JohnFornaro »
Sometimes I just flat out don't get it.

Offline Star One

  • Senior Member
  • *****
  • Posts: 7970
  • UK
  • Liked: 1274
  • Likes Given: 168
Re: EM Drive Developments
« Reply #209 on: 08/06/2014 02:17 PM »
I suppose the question to ask next is, Has NASA finally invented a thruster that finally defies Betterridge's Law of Headlines?


Color me skeptical after Flesichmann-Ponns, OPERA...

Great if it was true (or terrifying considering the inevitable military applications) but I will wait a while this blows over and see if it sticks.

What military applications, I could see you could produce a very stealthy air vehicle through it but what else?

Updated article based on the full paper.

http://nextbigfuture.com/2014/08/full-nasa-cannae-drive-and-emdrive-test.html

@JohnFornaro

What is they say extraordinary claims need extraordinary evidence to back them up.
« Last Edit: 08/06/2014 02:21 PM by Star One »

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 2896
  • Liked: 475
  • Likes Given: 719
Re: EM Drive Developments
« Reply #210 on: 08/06/2014 03:02 PM »
What military applications, I could see you could produce a very stealthy air vehicle through it but what else?
As you say, stealth is one thing, the other is endurance. With solar cells, this thing could stay aloft for a long time, provided it really works as advertised...

Offline DMeader

  • Full Member
  • ****
  • Posts: 953
  • Liked: 98
  • Likes Given: 47
Re: EM Drive Developments
« Reply #211 on: 08/06/2014 04:36 PM »
From xkcd:

Offline frobnicat

  • Full Member
  • ****
  • Posts: 518
  • Liked: 500
  • Likes Given: 151
Re: EM Drive Developments
« Reply #212 on: 08/06/2014 06:16 PM »
Back of the envelope rough order of magnitude basic physics principles sanity check :

Let's call L the thrust to power ratio (all SI)
For recall L for physically accepted photon rocket is 1/c = 3e-9 N/W
Cannae cavities tests claim about (order of magnitude) 1µN/W = 1e-6 N/W
Based on the Chinese experiments and their (empiric ?) formulas they expect possibility about 1N/kW = 1e-3 N/W

( I wonder on the nearly 3 orders of magnitude better results of Chinese ... why couldn't they try to replicate the exact same setup, even lower power as thrust would scale linearly or are there expected non linearities with power density ? )

On a given inertial frame a ship of mass M that goes from speed V to speed V+dV in a small time step dt will gain a kinetic energy dE=1/2 M (V˛+2VdV+dV˛ - V˛)=MVdV (discarding second order). That's a received power (in kinetic energy form in the given inertial frame) Pr = dE/dt = MVdV/dt = MVa = MVF/M = VF  ( where F is the thrust and a=F/M is the acceleration of the ship)
Pu is power used by the EM drive : L=F/Pu  or F=LPu, replacing F in above result : Pr=VLPu and finally Pr/Pu=VL

If the ship speed V is faster than Vf=1/L on any given inertial frame then it is now gaining more kinetic energy (relative to this arbitrary frame) than it is spending from its onboard generator. For a photon rocket Vf = c, nice because any arbitrary frame wont get you there.
For the tested and expected devices Vf goes from (again very roughly) 1000 km/s (Cannae) to 1km/s (about Chinese claims and what get them to Saturn in 9 Months straight, or rather  2.5km/s given 0.4 N/kW)

That is IF this L ratio wont depend on some absolute reference frame... So you are not only pushing on a medium that conveniently is always harvested at 0 speed relative to your ship, by doing so you are gaining more energy than spending as soon as above a very modest speed (relative to whatever ground), effectively pumping into the zero point vacuum. They even seem to hope for L=4N/kW, that's a Vf of 250m/s, that's slow enough to be mounted around a rotor : compact free energy generator ! Is this consequence seriously addressed by the Q-thruster theorists ?

If the L ratio depend on some absolute reference frame then the effect would be of lower magnitude when approaching those speeds relative to this frame. Back to aether problems : locally anchored to nearest massive body ? Else the effect would depend on orientation (Michelson-Morley...)

Vf stands for "Velocity of free energy", or "Velocity fishy"

« Last Edit: 08/06/2014 11:04 PM by frobnicat »

Offline SteveKelsey

Re: EM Drive Developments
« Reply #213 on: 08/06/2014 07:32 PM »
I agree with aero the report is worth a careful read. Much of the critique on this thread is answered.
The parts of the report that struck me as being  interesting are:-

There were four test elements

1)   A Shawyer based truncated cone design ( There are images of the closed end in the report John F : ) )
2)   A Cannae Test component with slots
3)   A Cannae test component without slots
4)   A Null test component consisting of a 50 ohm resistive load

The Null test article was useful in identifying a 9.6  micronewton force due to a 5.6 amp current running in the DC supply cable. This Null Force’ was subtracted from the results.

It is reported that the torsion balance can measure down to 1 micronewton

The test protocol included pre and post test calibrations of the balance for each run

Of the four items tested  the 50 ohm load did not produce a force

All of the three test articles, including the Cannae test article without slots  which was anticipated would NOT produce a thrust , produced thrusts well above the sensitivity limit of the balance.

The dielectric does seem to be significant.

It is also clear that this report is part of an ongoing program and the next step is to test at higher power and in a hard vacuum.

Not what I expected, and interesting.

It may still be the result of a test protocol anomaly but there is reason to continue.
« Last Edit: 08/06/2014 07:51 PM by SteveKelsey »
2001 is running a little late, but we are getting there.

Offline Star One

  • Senior Member
  • *****
  • Posts: 7970
  • UK
  • Liked: 1274
  • Likes Given: 168
Re: EM Drive Developments
« Reply #214 on: 08/06/2014 08:14 PM »
Guys I applaud trying to stay on topic, but you're giving so little detail I have no idea what you're talking about. Going to that site shows some terrible "scientific" thoughts, is that what you mean.

Perhaps it needs a separate thread on "misunderstanding science" or whatever the concern is - otherwise an illustration of your concern would be great :)

See link below.

http://www.talk-polywell.org/bb/viewtopic.php?f=10&t=5469

Make of what is posted in there what you will.
« Last Edit: 08/06/2014 08:25 PM by Star One »

Offline IslandPlaya

  • Full Member
  • ****
  • Posts: 582
  • Outer Hebrides
  • Liked: 163
  • Likes Given: 166
Re: EM Drive Developments
« Reply #215 on: 08/06/2014 08:29 PM »
Am proud to be part of the Interesting Times Gang (Thanks Mr Banks.)
I really am intrigued to see the scientific method working properly here (not the blogosphere.) We will see hopefully sooner rather than later what is going on.
 ;D

Offline Space OurSoul

  • Full Member
  • **
  • Posts: 235
  • Seattle, WA
  • Liked: 140
  • Likes Given: 36
Re: EM Drive Developments
« Reply #216 on: 08/06/2014 08:37 PM »
XKCD weighs in:

http://xkcd.com/1404/
A complete OurSoul

Offline IslandPlaya

  • Full Member
  • ****
  • Posts: 582
  • Outer Hebrides
  • Liked: 163
  • Likes Given: 166
Re: EM Drive Developments
« Reply #217 on: 08/06/2014 08:40 PM »
Guys I applaud trying to stay on topic, but you're giving so little detail I have no idea what you're talking about. Going to that site shows some terrible "scientific" thoughts, is that what you mean.

Perhaps it needs a separate thread on "misunderstanding science" or whatever the concern is - otherwise an illustration of your concern would be great :)

See link below.

http://www.talk-polywell.org/bb/viewtopic.php?f=10&t=5469

Make of what is posted in there what you will.
Just speed-read that thread. Isn't GIThruster someone who was banned from NSF back-in-the-day before my time here? What was the score with him? (I can probably guess..)
I'm glad to be with sensible people who can discuss this properly here at NSF.

Offline Star One

  • Senior Member
  • *****
  • Posts: 7970
  • UK
  • Liked: 1274
  • Likes Given: 168
Re: EM Drive Developments
« Reply #218 on: 08/06/2014 09:04 PM »
Guys I applaud trying to stay on topic, but you're giving so little detail I have no idea what you're talking about. Going to that site shows some terrible "scientific" thoughts, is that what you mean.

Perhaps it needs a separate thread on "misunderstanding science" or whatever the concern is - otherwise an illustration of your concern would be great :)

See link below.

http://www.talk-polywell.org/bb/viewtopic.php?f=10&t=5469

Make of what is posted in there what you will.
Just speed-read that thread. Isn't GIThruster someone who was banned from NSF back-in-the-day before my time here? What was the score with him? (I can probably guess..)
I'm glad to be with sensible people who can discuss this properly here at NSF.

Much appreciate the background info and I apologise if people think the thread was inappropriate as a result, I would say in my defence I didn't know he had a known NSF history.
« Last Edit: 08/06/2014 09:04 PM by Star One »

Offline IslandPlaya

  • Full Member
  • ****
  • Posts: 582
  • Outer Hebrides
  • Liked: 163
  • Likes Given: 166
Re: EM Drive Developments
« Reply #219 on: 08/06/2014 09:11 PM »
I really don't know about him/her. Maybe someone who has been here longer can elucidate?
I seem to remember a thread title being "....... (GIThruster, now banned.)....."
Anyway, it doesn't really matter. The thread you linked was interesting but was more full of vitriol than science and reason. IMHO

Tags: