Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum. - Page 1
Forum section: electronics / general

author: firewalker
author_rank: Super Contributor
timestamp: November 19, 2016, 10:12:25 am
content: The final results.https://science.slashdot.org/story/16/11/18/2230229/final-nasa-eagleworks-paper-confirms-promising-em-drive-resultsAlexander.

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 19, 2016, 08:31:39 pm
content: You may need a better title for your post likeLAWS OF PHYSICS BROKEN!! EM DRIVE PROVEN TO WORK!!!!Don't know what to make of this. Is this one where people need to figure out what they did wrong with their experiment?I guess the next step is replicate, explain...

author: firewalker
author_rank: Super Contributor
timestamp: November 19, 2016, 10:35:35 pm
content: Did anyone manage to download the actual paper?Alexander.

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 19, 2016, 10:51:07 pm
content: Yes.PDF:http://arc.aiaa.org/doi/pdf/10.2514/1.B36120HTML:http://arc.aiaa.org/doi/10.2514/1.B36120

author: firewalker
author_rank: Super Contributor
timestamp: November 19, 2016, 11:01:04 pm
content: It always say "Ip banned". I tried several different computers and ips. Even tor.Alexander.

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 19, 2016, 11:44:35 pm
content: Maybe try going through a web proxy?

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 19, 2016, 11:56:42 pm
content: Looks like the paper was leaked earlier. These look pretty much the same as the published paper:http://www.thisweekintomorrow.com/wp-content/uploads/2016/11/Q-Thruster-In-Vacuum-Fall-2015-Test-Report.pdfhttp://www.focus.it/site_stored/imgs/0005/046/q-thrusterin-vacuum-fall-2015-test-report.pdf

author: John Coloccia
author_rank: Super Contributor
timestamp: November 20, 2016, 12:11:55 am
content: Quote from: rfeecs on November 19, 2016, 08:31:39 pmPersonally, I think the thing probably works. There's nothing particularly fundamental about conservation of momentum. It's a first principle that's taken on faith and backed by experiment. Even if a more reasonable explanation can't be found that doesn't violate this conservation law, what typically happens is you realize that it's part of some deeper, even more fundamental conservation law that simply wasn't apparent where/how we were looking.

author: Brumby
author_rank: Unknown
timestamp: November 20, 2016, 12:25:33 am
content: Quote from: rfeecs on November 19, 2016, 08:31:39 pmIs your suggested title simply one for clickbait - or do you believe the laws of physics would need to be broken?If the latter - why?

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 20, 2016, 12:42:51 am
content: Yes, it's more for click bait. I think it's an interesting subject that people might pass over because of the title.Is there a classical physics explanation of how this thing generates thrust?I realize people are working on proposing quantum mechanical arguments of what might be happening.I am a little suspicious this might be a case like the neutrinos that were going faster than the speed of light.Or cold fusion.But it would be exciting if it were real.

author: IanB
author_rank: Super Contributor
timestamp: November 20, 2016, 01:00:01 am
content: Quote from: rfeecs on November 20, 2016, 12:42:51 amTo begin with, it does have to be real. Which means first the paper has to describe exactly the experimental setup and conditions to reproduce the effect, and second two or three other experimenters have to independently reproduce the same measurements in different labs. After that has been done, then people can search for an explanation.

author: Brumby
author_rank: Unknown
timestamp: November 20, 2016, 01:16:01 am
content: Quote from: IanB on November 20, 2016, 01:00:01 amI'd start with one of these....

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 20, 2016, 01:27:54 am
content: Quote from: Brumby on November 20, 2016, 01:16:01 amThe Crookes radiometer doesn't work in a vacuum. It doesn't work by radiation pressure. I don't see the connection.

author: Brumby
author_rank: Unknown
timestamp: November 20, 2016, 01:38:24 am
content: Entry-level teaser.Simple experiment that appears to demonstrate something - but working out what is actually going on will lead onto bigger and better things.

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 21, 2016, 08:00:47 pm
content: I stumbled across this video. A physicist's reaction to the paper.He's skeptical. It would mean you could make a perpetual motion machine, etc:https://youtu.be/JGcvxg7jJTs

author: Augustus
author_rank: Regular Contributor
timestamp: November 21, 2016, 09:22:44 pm
content: Put this thing into a satellite, shoot it into space and check if it works, simple as that

author: raspberrypi
author_rank: Frequent Contributor
timestamp: November 21, 2016, 11:39:57 pm
content: Quote from: Augustus on November 21, 2016, 09:22:44 pmDon't do it on a spaceX rocket. Why is spaceX reinventing the wheel? Anyways is there a midlevel explanation of how this works? I do understand a bit of quantum physics. It seems you either get an extremely technical explanation, or it's really dumbed down that doesn't include even a hint of the math needed to actually understand, and not just take their word for it.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: November 22, 2016, 01:50:06 am
content: Read the paper. You will see that only the most liberal interpretation of the data could show that "it works". For example, the effect does not scale with applied power (the 80 watt displacements are pretty much the same as the 60 w displacements and in some cases are even smaller.) The error bars on the data exceed the effect size. The "thrust" continues after RF power is removed. After RF power is removed there is a displacement in the opposite direction. And etc.There are also problems with the experimental setup. Look at the size of the vacuum chamber compared to the test article.So don't go getting all excited about this report. Maybe it's worth testing in space, but I think this paper is essentially reporting a null result, with "thrust" due to experimental artifact and statistical errors.

author: Cerebus
author_rank: Super Contributor
timestamp: November 22, 2016, 02:11:17 am
content: Quote from: Brumby on November 20, 2016, 12:25:33 am"What are you rebelling against?""Whata ya got?"

author: Brumby
author_rank: Unknown
timestamp: November 22, 2016, 03:02:06 am
content: Curiosity ... and an open mind with a cynical streak.

author: TerraHertz
author_rank: Super Contributor
timestamp: November 22, 2016, 03:34:05 am
content: It sure is tantalizing. A pity their test setup has some sillies, like mounting the entire RF generation system on the torsion balance. Including the bulky heatsink (in a vacuum, so their run time was quite limited.)Haven't they heard of waveguide rotational joints? I'm sure there must be something like that, which has no physical contact between the halves.Anyway, it will be more interesting if anyone ever finds a way to get more thrust, like multiple Newtons as opposed to the pathetic (and potentially an artifact) 1.2mN/KWThe most interesting thing in the papers is the photos of their setup. You can get bigger size images fromhttp://arc.aiaa.org/doi/10.2514/1.B36120(the HTML version), clicking on the tiny images, then in the 'slideshow', clicking on the "Show full size" link down the bottom. Ridiculous rigmarole, but gets there in the end. And someone should buy them a better camera.Pics attached.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: November 22, 2016, 04:36:26 am
content: That "1.2mN/KW" figure is also hilarious, as it implies that the thrust scales with power, when their own data shows very clearly that it does not. The maximum power tested was only 80 watts, and they did not get more thrust than they got with 60 watts, and in some cases even got _less_ thrust with 80 w than they did with 60 w. See Table 2 in the paper.But of course citing a thrust figure of 0.0000012 Newton per Watt doesn't look nearly as impressive as 1.2mN/KW.

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 22, 2016, 04:58:56 am
content: Quote from: TerraHertz on November 22, 2016, 03:34:05 amI'm thinking you need to put the generator on the torsion balance. Otherwise you might not be accounting for momentum transferred from the generator through the waveguide.Quote from: TerraHertz on November 22, 2016, 03:34:05 amThey did get 1.2N per MW!

author: John Coloccia
author_rank: Super Contributor
timestamp: November 22, 2016, 05:12:53 am
content: Quote from: alsetalokin4017 on November 22, 2016, 04:36:26 amBut they got more thrust at 60W than 40W.