Em drive good news...

[KSK]

22 hours ago, p1t1o said:

@5thHorseman @monstah I cant believe you *both* forgot to realign the navigational deflector...

Just don't forget the servicing and maintenance. Regular baryon sweeps will keep your deflector in tip-top working order.

 

[DaMichel]

Thunderf00t made a video about it, too ... A brutal debunking video.

 

[Steel]

39 minutes ago, DaMichel said:

Thunderf00t made a video about it, too ... A brutal debunking video.

 

Not really a debunking video, simply a statement of the facts presented by the revered "NASA" paper

Edited November 29, 2016 by Steel

[PB666]

On 11/8/2016 at 7:29 AM, Tullius said:

The ion thrusters of Dawn produced nearly 40 mN/kW , i.e. 30 times more thrust for the same amount of electricity than the EM-drive.

But considering that the EM-drive doesn't need a propellant, it is actually not that bad.

Its pretty bad, because on an ION drive you loose mass and thrust. So overtime the ship gets lighter. For longterm spaceflight assumming Mg ION drive you could have 3 or 4 times the ships weight in feul, you could easily make up for the fact that there is no mass loss by the fact that the ION thrusters are 35 times more energy efficient, and given NTGs are weight and solar panels are weighty also, you would need 35 times as many of these to get the same thrust as ION thruster. I take the solid fuel or even a dense gas over the Cannae drive any day.

Where these things might pay off is if you had a shuttle that went between L2-L1 earth mars and back, a hauler where you didn't need much DV reasonably close to the sun that you can have panels, and you were going back and forth. Suppose you were shuttling dry stock goods, like grains, wood or metal, even meat frozen to -50'C which you could hold for years at a time. This type of transport could pay off because it becomes free of cost. BUT  - - - - - - - - -  - - - - -

We still don't know whether that efficiency will remain in space, in space it might drop to 1mN/300kW.

I might also add, it might make a good interstellar terraforming drive, you have 1000 years to reach 0.005 C then 1000 years to slow down, meh, the lypohilized bugs won't mind.

 

 

On 11/8/2016 at 8:15 AM, magnemoe said:

The tested device is not the one with highest trust/effect ratio. 
It was one with least amount of error sources like thermal expansion or outgassing. 

The work to optimize the design starts now as it looks like they have an workable device. 
The guy who made his own drive managed 18 mN/KW with an cruder but larger design (only tested in atmosphere) 
Think some earlier NASA designs got higher than 10 mN in vacuum too. 
No idea how high they can take this.
 

Yeah, no this is not credible.

 

Edited November 29, 2016 by PB666

[PakledHostage]

Another video attempting to remain objectively realistic about the topic was just released today by PBS Space Time:

 

[Scotius]

No new info. Unfortunately this video is just rehashing old data. It kinda irks me - scientists who actually build and tested EMDrives say "Yes, it's weak but it works." At the same time people who DIDN'T took part in building and testing of said test articles say: "It doesn't work, because it can't.". YT experts...

[Nuke]

everyones rooting for the wrong drives. mach effect thrusters have solid theory behind them, other labs get similar results (you find that em drive tests yield wildly different results in comparison), and scaling laws exist, so we know how to improve their performance (its mostly a materials problem).

everyone seemed to miss this thread i made about the ssi conference held back in september.

http://forum.kerbalspaceprogram.com/index.php?/topic/154661-geeking-out-on-exotic-propulsion-mach-effect-em-etc/

 

Edited January 12, 2017 by Nuke

[Scotius]

I bet it's due to the alluring simplicity of EMdrive While Mach thruster would require exotic and expensive materials to get the best results, EMdrive basically is a sheet of bent copper with a part of a microwave welded on

[p1t1o]

If you ask me, the "EMDrive" is not primarily interesting as a drive, but the fact that we're not sure what is happening yet.

2 hours ago, Scotius said:

No new info. Unfortunately this video is just rehashing old data. It kinda irks me - scientists who actually build and tested EMDrives say "Yes, it's weak but it works." At the same time people who DIDN'T took part in building and testing of said test articles say: "It doesn't work, because it can't.". YT experts...

Actually I percieve the opposite - scientists who have tested it saying "We seem to be getting something but we are not sure if it is real yet" and hundreds of blogs and youtyoobs saying "New SpaceDrive^TM violates the laws of thermodynamics! Scientists dont know how science works! Dont trust scientists!"

[KSK]

Ars Technica ran a pretty good article on this. The title is a bit contentious but the article itself is worth a read. The impression I got was that testing this in a lab is hard (because we're measuring a very small force), the favoured apparatus for doing those tests (torsion balance) is notoriously finicky at the best of times, and so the testing done so far hasn't been terribly rigorous. Hence @p1t1o's 'we're not sure if this is real' comment seems fair.

Likewise much of the 'theory' around this thing would make marvelous technobabble for a Star Trek episode but that's about it.

[hms_warrior]

It is even worse becasue there is no theory predicting this thing.

This means if you build one and run it you never know if the result you get is "true"

Example: you build one and get no reaction. Now do you get no reaction because this thing is a lie? or did one of the hundred things you did just a tiny bit different than that other guy who did get a positive result?

You get a result that is stronger than everything before....did one of those little things you did different improved the drive or do you have some thermal/magnetical/whatever force screwing you up?

[Green Baron]

25 minutes ago, hms_warrior said:

 

This means if you build one and run it you never know if the result you get is "true"

 

lol ... cleverly arranged, isn't it :-))

 

[PakledHostage]

2 hours ago, p1t1o said:

If you ask me, the "EMDrive" is not primarily interesting as a drive, but the fact that we're not sure what is happening yet.

Actually I percieve the opposite - scientists who have tested it saying "We seem to be getting something but we are not sure if it is real yet" and hundreds of blogs and youtyoobs saying "New SpaceDrive^TM violates the laws of thermodynamics! Scientists dont know how science works! Dont trust scientists!"

If you are referring to the video that I posted, then I think you are being overly harsh. Did you even watch it? Nobody in this video said anything remotely close to "Scientists dont know how science works! Dont trust scientists!"

They make the same point that you do: That it is potentially interesting because, if it works, it reveals something about physics that we don't understand.

But, he also makes the point that extraordinary claims require extraordinary evidence and there is a bunch of work that needs to be done to rule out the mundane explanations before we get to those more extraordinary explanations. Even the study's authors identified testing that needs to be done in that regard.

 

Edited January 12, 2017 by PakledHostage

[p1t1o]

Just now, PakledHostage said:

If you are referring to the video that I posted, then I think you are being overly harsh. Did you even watch it?

They make the same point that you do: That it is potentially interesting because, if it works, it reveals something about physics that we don't understand.

But, he also makes the point that extraordinary claims require extraordinary evidence and there is a bunch of work that needs to be done to rule out the mundane explanations before we get to those explanations. Even the study's authors identified some testing that needs to be done in that regard.

Nobody said "Scientists dont know how science works! Dont trust scientists!" At least not in this video.

Ah, dont worry, no not specifically the video that you posted, its the gestalt-feeling I get from all of the places where I have seen it mentioned. Naturally, some sources are better than others

[PakledHostage]

Jeesh! That was quick. You didn't even let me finish my post-posting cleanup...

[YNM]

Well one can always do it by brute force - send one to space, ad see where can it go.

[sal_vager]

It'd be funny if it turns out to have a torque no one has noticed yet, causing it to go in circles unless you have two of them, maybe like this...

[p1t1o]

18 minutes ago, PakledHostage said:

Jeesh! That was quick. You didn't even let me finish my post-posting cleanup...

Sorry I hate when that happens!

11 minutes ago, YNM said:

Well one can always do it by brute force - send one to space, ad see where can it go.

Didnt someone send one up recently? Or was that just a rumour?

[rfmwguy]

I think this episode sets the standard for moving forward with experimentation with an open, yet skeptical mind. Its hard to argue against further testing as a displacement force was noted in many experiments. Whether that was in the noise, a mundane effect or something undiscovered certainly justifies further efforts considering the potential. Pretty logical conclusion from this episode.

[YNM]

9 minutes ago, p1t1o said:

Sorry I hate when that happens!

Didnt someone send one up recently? Or was that just a rumour?

If they need megawatt(s) of power for such tiny thrust, then the smallest one should have some panels as big as 1000 m2. That should be big enough so any launch should be noticeable. (1000 m2 works to around 33*30 m or 22*22 m for two panels)

[wumpus]

2 hours ago, hms_warrior said:

It is even worse becasue there is no theory predicting this thing.

Sort of.  The whole idea of the device was dreamed up because the shape implied a difference when fed through the equations implied difference in momentum applied to the two sides.  Some experimental data appears to confirm this (it is sufficiently small to be inconclusive).

On 11/29/2016 at 5:37 PM, PB666 said:

Where these things might pay off is if you had a shuttle that went between L2-L1 earth mars and back, a hauler where you didn't need much DV reasonably close to the sun that you can have panels, and you were going back and forth. Suppose you were shuttling dry stock goods, like grains, wood or metal, even meat frozen to -50'C which you could hold for years at a time. This type of transport could pay off because it becomes free of cost. BUT  - - - - - - - - -  - - - - -
...
I might also add, it might make a good interstellar terraforming drive, you have 1000 years to reach 0.005 C then 1000 years to slow down, meh, the lypohilized bugs won't mind.

Even going between Earth-Mars, you could presumably pick up enough Xenon (or Argon if you used too much) for each trip.  An em drive is pretty silly for anything other than interstellar (where the mass for the ion drive will eventually run out).  I'd still think you could use cyclotron tricks to get a lot more Isp out of your ions if you cared enough (i.e. if you were going interstellar, once you hit 4 figures of Isp for interplanetary missions other factors become more important).

And yes, this really reminds me of the time that a credible research team kept seeing objects going faster than light... eventually they found the cable plugged into the wrong place.

[magnemoe]

43 minutes ago, YNM said:

If they need megawatt(s) of power for such tiny thrust, then the smallest one should have some panels as big as 1000 m2. That should be big enough so any launch should be noticeable. (1000 m2 works to around 33*30 m or 22*22 m for two panels)

Some leak that China tested it on their space station. Not sure if true or how useful, it would still be close to an huge metal object. 
Simpler is an cube / micro sat, you don't need much trust just enough that orbital period increases over time. 

This only prove if the drive works who would do wonder for funding. No effect can also be broken drive. 

[sal_vager]

1 hour ago, p1t1o said:

Didnt someone send one up recently? Or was that just a rumour?

Guido Fetta plans to put a cannae drive in orbit, but that's a little different to the EMdrive but journalists usually confuse the two.

[HebaruSan]

9 hours ago, Nuke said:

everyone seemed to miss this thread i made about the ssi conference held back in september.

http://forum.kerbalspaceprogram.com/index.php?/topic/154661-geeking-out-on-exotic-propulsion-mach-effect-em-etc/

To be fair, that post didn't explain anything about the drives (or mention what SSI stands for); it just gave some links and said there was stuff to watch or read. Almost more like a homework assignment than a post; and speaking only for myself, there's a decent chance that I'd find presentations from a professional conference hard to understand, impossible to watch, or both. An explanation of the workings of the drive you consider the one to watch might prompt more of a response.

[Nuke]

yea i probibly should have come up with a better description. i was only half way through the videos myself before i had to post about it. if you watch nothing else, watch woodward's video on page 3.