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NASA's 'impossible' EM Drive works: German researcher confirms (2015)

14 points by cryled 11y ago

cryled 11y ago
https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster http://forum.nasaspaceflight.com/index.php?topic=39004.0 http://forum.nasaspaceflight.com/index.php?topic=39004.0
JoeAltmaier 11y ago
tl;dr: no it doesn't; no it wasn't
cryled 11y ago
Paper cited by article does not confirm it works: "Our test compaign therefore cannnot confirm nor refute the claims of the EMDrive but intends to independantly assess possible side-effects in the measurement methods used so far" http://forum.nasaspaceflight.com/index.php?topic=38577.msg1440938#msg1440938 http://forum.nasaspaceflight.com/index.php?topic=38577.msg14... Wondering why didn't NASA send a EMDrive to space already and just see if it works or not on real conditions instead of testing it on a laboratory?
- ehnto 11y ago
  I imagine the cost coupled with the timeline of other experiments. It's certainly not a trivial thing to do.
snissn 11y ago
Oh cool, another crack pot physics post on hacker news!
- MCRed 11y ago
  IT's a nice change of pace from the crackpot economics posts that normally fill the homepage.
- vixen99 11y ago
  If you have sure-fire evidence that this is indeed 'crackpot' then you should bring it forward otherwise you're offering an opinion minus pertinent observation or support. Perhaps I'm wrong but why should that be interesting enough to post here? Most of the British newspapers including the Guardian and Daily Mail provide an outlet for such comments.
JamesGDev 11y ago
Ok, so this article says: > The EM drive is so thrilling because it yields enormous amounts of propulsion Yet IFL-Science says: > What it actually does is produce a tiny, tiny amount of thrust via a method that’s not entirely understood. I know which one I trust.. Can this be down voted for not been factual.?
- mitchty 11y ago
  The enormous is likely referring to efficiency of the mass to work. Ion engines are similar in that regard. They're great in that it is a constant thrust even though the impulse is low. Now as to why this may produce thrust, I'll wait until we validate it with physics.
- cryled 11y ago
  tiny, tiny amount of thrust during large, large amounts of time = enormous amounts of propulsion... I know article is awful, sorry about that; submited only just because I wanted to read more comments about EMDrives on HN as I think they are cool; and the way HN works old threads are never seen again by most users...
  - JamesGDev 11y ago
    haha, no need to apologise, this site is full of educated people who make up their own mind. I think I snapped a little with my comment (mid way building an iPhone App so stressed) Apologies.
packetized 11y ago
Can we get a [2015] tag?
roywiggins 11y ago
A functioning massless drive is arguably as unlikely as a perpetual motion machine. It's not really worth paying attention to claims that someone built one other than perhaps as entertainment value.
- SAI_Peregrinus 11y ago
  It IS a perpetual motion machine. Stick a few of them on a generator's rotor so that they'll spin it when powered. Use the generated power to run them, and harvest the excess. Infinite free energy!
Animats 11y ago
This paper (non-paywall version)[1] is from last August. It's another one of those phenomenon that's so near the noise threshold that it's hard to measure reliably. They get forces around 70 μN. This is very small, and although they have a balance sensitive enough to measure it, there are lots of effects which can produce tiny forces like that. The experimental work described in the paper is disappointing, in that the original cavity system apparently had a Q of something like 100,000, but their system only has a Q of 50, because it's mistuned for the microwave oven magnetron they're using. ("Unfortunately, the absorption peak at the resonance we were aiming at was smaller then expected (probably also due to misalignments after soldering).") The highest thrust reported by anybody with this is 720 mN, but that was in air. They're almost four orders of magnitude below that, in vacuum. For reference, the ion thrusters on the Dawn spacecraft deliver 90mN. If they had hardware that generated 720mN in air, and tried that in hard vacuum, that would be useful. (In air, all sorts of things, such as heating or electrostatic repulsion, can generate air movement and thus tiny amounts of thrust. So results in air are not too interesting.) [1] http://moscow.sci-hub.bz/ded43880657f12f27fc596f46abbbfe6/10.2514@6.2015-4083.pdf http://moscow.sci-hub.bz/ded43880657f12f27fc596f46abbbfe6/10...
xbmcuser 11y ago
Best way to test the engine is for Elon Musk to make one and send it up on his rocket if it works then he can bring his timeline for mars down a few years.
xbmcuser 11y ago
Best way to test the engine is for Elon Musk to make one and send it up on his rocket if it works then he can bring his timeline for mars down a few years.

14 points by cryled 11y ago

https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster http://forum.nasaspaceflight.com/index.php?topic=39004.0 http://forum.nasaspaceflight.com/index.php?topic=39004.0

JoeAltmaier 11y ago

tl;dr: no it doesn't; no it wasn't

cryled 11y ago

Paper cited by article does not confirm it works: "Our test compaign therefore cannnot confirm nor refute the claims of the EMDrive but intends to independantly assess possible side-effects in the measurement methods used so far" http://forum.nasaspaceflight.com/index.php?topic=38577.msg1440938#msg1440938 http://forum.nasaspaceflight.com/index.php?topic=38577.msg14... Wondering why didn't NASA send a EMDrive to space already and just see if it works or not on real conditions instead of testing it on a laboratory?

ehnto 11y ago
I imagine the cost coupled with the timeline of other experiments. It's certainly not a trivial thing to do.

snissn 11y ago

Oh cool, another crack pot physics post on hacker news!

MCRed 11y ago
IT's a nice change of pace from the crackpot economics posts that normally fill the homepage.
vixen99 11y ago
If you have sure-fire evidence that this is indeed 'crackpot' then you should bring it forward otherwise you're offering an opinion minus pertinent observation or support. Perhaps I'm wrong but why should that be interesting enough to post here? Most of the British newspapers including the Guardian and Daily Mail provide an outlet for such comments.

JamesGDev 11y ago

Ok, so this article says: > The EM drive is so thrilling because it yields enormous amounts of propulsion Yet IFL-Science says: > What it actually does is produce a tiny, tiny amount of thrust via a method that’s not entirely understood. I know which one I trust.. Can this be down voted for not been factual.?

mitchty 11y ago
The enormous is likely referring to efficiency of the mass to work. Ion engines are similar in that regard. They're great in that it is a constant thrust even though the impulse is low. Now as to why this may produce thrust, I'll wait until we validate it with physics.
cryled 11y ago
tiny, tiny amount of thrust during large, large amounts of time = enormous amounts of propulsion... I know article is awful, sorry about that; submited only just because I wanted to read more comments about EMDrives on HN as I think they are cool; and the way HN works old threads are never seen again by most users...
- JamesGDev 11y ago
  haha, no need to apologise, this site is full of educated people who make up their own mind. I think I snapped a little with my comment (mid way building an iPhone App so stressed) Apologies.

packetized 11y ago

Can we get a [2015] tag?

roywiggins 11y ago

A functioning massless drive is arguably as unlikely as a perpetual motion machine. It's not really worth paying attention to claims that someone built one other than perhaps as entertainment value.

SAI_Peregrinus 11y ago
It IS a perpetual motion machine. Stick a few of them on a generator's rotor so that they'll spin it when powered. Use the generated power to run them, and harvest the excess. Infinite free energy!

Animats 11y ago

This paper (non-paywall version)[1] is from last August. It's another one of those phenomenon that's so near the noise threshold that it's hard to measure reliably. They get forces around 70 μN. This is very small, and although they have a balance sensitive enough to measure it, there are lots of effects which can produce tiny forces like that. The experimental work described in the paper is disappointing, in that the original cavity system apparently had a Q of something like 100,000, but their system only has a Q of 50, because it's mistuned for the microwave oven magnetron they're using. ("Unfortunately, the absorption peak at the resonance we were aiming at was smaller then expected (probably also due to misalignments after soldering).") The highest thrust reported by anybody with this is 720 mN, but that was in air. They're almost four orders of magnitude below that, in vacuum. For reference, the ion thrusters on the Dawn spacecraft deliver 90mN. If they had hardware that generated 720mN in air, and tried that in hard vacuum, that would be useful. (In air, all sorts of things, such as heating or electrostatic repulsion, can generate air movement and thus tiny amounts of thrust. So results in air are not too interesting.) [1] http://moscow.sci-hub.bz/ded43880657f12f27fc596f46abbbfe6/10.2514@6.2015-4083.pdf http://moscow.sci-hub.bz/ded43880657f12f27fc596f46abbbfe6/10...

xbmcuser 11y ago

Best way to test the engine is for Elon Musk to make one and send it up on his rocket if it works then he can bring his timeline for mars down a few years.

xbmcuser 11y ago

Best way to test the engine is for Elon Musk to make one and send it up on his rocket if it works then he can bring his timeline for mars down a few years.