Em drive good news...

[NeverEnoughFuel!!]

Well I stumbled on this today... http://www.digitaltrends.com/cool-tech/nasa-paper-emdrive/

and this https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU/view

Can someone of math whiz guys calculate how much thrust you would get from let's say 1 megawatt? There are  submarines with up to 12 MW reactors...

[Steel]

31 minutes ago, NeverEnoughFuel!! said:

Well I stumbled on this today... http://www.digitaltrends.com/cool-tech/nasa-paper-emdrive/

and this https://drive.google.com/file/d/0B7kgKijo-p0ibm94VUY0TVktQlU/view

Can someone of math whiz guys calculate how much thrust you would get from let's say 1 megawatt? There are  submarines with up to 12 MW reactors...

Well the paper's abstract gives us the headline figure of 1.2 (+/- 0.1) mN/kW, so 1 MW (assuming a perfectly linear relationship) would give 1.2 N of thrust.

 

Interesting to note that the authors, in their own conclusion, cede that the effects of thermal expansion were only "addressed to a degree" and that further testing would need to be performed to completely rule out thermal expansion having an impact on reported results.

EDIT: Reading a little further, even the units of the headline figure are a little odd, considering it quotes a figure in mN/kW, when in fact their tests only go up to 80W. It's a fair bit of extrapolation to go from 80W to 1000W...

EDIT #2: also can we please talk about how these guys have assumed a straight line fit over a range of input power in the kilowatts, based on a data set of three points over range of 40W...

Edited November 8, 2016 by Steel

[Nefrums]

1 minute ago, NeverEnoughFuel!! said:

Can someone of math whiz guys calculate how much thrust you would get from let's say 1 megawatt? There are  submarines with up to 12 MW reactors...

Well it hardly takes a math whiz to put 1 MW into:   1,2+- 0,1 mN/kW   you get: 1.2 N

 

[NeverEnoughFuel!!]

Ooookaaaay (Will Smith in MiB)...and how much is that? Too little? 

[Steel]

1 minute ago, NeverEnoughFuel!! said:

Ooookaaaay (Will Smith in MiB)...and how much is that? Too little? 

1.2 N is the force you would feel on your hand due to gravity if you placed a 120g mass on it.

[Tullius]

1 minute ago, NeverEnoughFuel!! said:

Ooookaaaay (Will Smith in MiB)...and how much is that? Too little? 

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.

[NeverEnoughFuel!!]

So for 1kilonewton you would need gigawatts? Seems KSPI is right after all... lol

[Nefrums]

11 minutes ago, NeverEnoughFuel!! said:

Ooookaaaay (Will Smith in MiB)...and how much is that? Too little? 

it is about two orders of magnitude less than an ion engine but two orders of magnitude more than a Photonic laser engine.

 

 

It is very interesting that not even Nasa where able to disprove this engine.

So Newtons first law disproved? Not likely, but what is making this work then?

 

Edited November 8, 2016 by Nefrums

[magnemoe]

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.
 

[Nefrums]

When they figure out how it works thre will likely be able to build something that have several orders of magnitude better thrust/W

[Darnok]

1 hour ago, Nefrums said:

So Newtons first law disproved? Not likely, but what is making this work then?

 

It is pushing away from "space". If you consider space as particle then it makes sense, but this makes quantum physics and relativity wrong... that is why EM inventor didn't wanted to explain "how does it work?" on his own

 

[magnemoe]

3 minutes ago, Darnok said:

It is pushing away from "space". If you consider space as particle then it makes sense, but this makes quantum physics and relativity wrong... that is why EM inventor didn't wanted to explain "how does it work?" on his own

Now how does the EM-drive behave regarding kinetic energy. 
Any rocket engine is an reaction engine propelling reaction matter backward, this gives and an constant acceleration if we ignore that the weight goes down because of less reaction mass. 

Doubtful the em-drive will have constant acceleration, if so you could get free energy, have an em-drive on an long rotating arm in vacuum, with an constant acceleration at some point the speed increase of drive would add more kinetic energy to the arm than you need to power it, you can now tap the kinetic energy with an generator and feed the em-drive with it. 

Outside reaction engines systems tend to be energy bound. Your car braking is an good example, force of braking is pretty constant, however your use four time longer to stop if your speed is twice as high as you need to get rid of your kinetic energy.
I assume this is true for the em-drive too, will the reference frame be the starting frame like low orbit or earth escape trajectory if sent out with an normal rocket engine? 
I assume an solar sail or magnetic sail would also be energy limited? 

[Nefrums]

7 minutes ago, magnemoe said:

Now how does the EM-drive behave regarding kinetic energy. 

1 W = 1 Nm/s

So you get about about a 1/10^6 of the energy you put in as kinetic energy.

 

[Darnok]

7 minutes ago, magnemoe said:

Now how does the EM-drive behave regarding kinetic energy. 
Any rocket engine is an reaction engine propelling reaction matter backward, this gives and an constant acceleration if we ignore that the weight goes down because of less reaction mass.
 

IF you consider space as particle, then you don't have to eject any particles from your engine, all you have to do is to create field that will push way from those space-particles, same as submarine engine is pushing away from water particles.

 

7 minutes ago, magnemoe said:

Doubtful the em-drive will have constant acceleration, if so you could get free energy, have an em-drive on an long rotating arm in vacuum, with an constant acceleration at some point the speed increase of drive would add more kinetic energy to the arm than you need to power it, you can now tap the kinetic energy with an generator and feed the em-drive with it. 
 

Em-drive has nothing to do with free energy, to power it up you need lots of energy.

[magnemoe]

26 minutes ago, Nefrums said:

1 W = 1 Nm/s

So you get about about a 1/10^6 of the energy you put in as kinetic energy.

 

 

5 minutes ago, Darnok said:

Em-drive has nothing to do with free energy, to power it up you need lots of energy.

True, however if you continue to accelerate at an constant rate your energy use is constant while your kinetic energy increase by an factor of two. 
At some point your kinetic energy will increase faster than the energy you use to power the drive. 
This is an common argument against the em-drive.
personally I think you will not get constant acceleration but that you will be limited by kinetic energy.

[Darnok]

16 minutes ago, magnemoe said:

 

True, however if you continue to accelerate at an constant rate your energy use is constant while your kinetic energy increase by an factor of two. 
At some point your kinetic energy will increase faster than the energy you use to power the drive. 
This is an common argument against the em-drive.
personally I think you will not get constant acceleration but that you will be limited by kinetic energy.

It should be limited by frequency of field that is generated by em-drive.

[NeverEnoughFuel!!]

So if we look at this in layman terms (as I am), and compare it to a submarine moving trough water... some invisible field (higs-bosson maybe or something similar) is water, and Em drive is a propeller, and frequency is rpm? And kinetic energy is water's drag/resistance? It seems to me that infinite acceleration is naturally impossible... just a layman... don't jump on me please!  

[Kerbart]

3 hours ago, Steel said:

EDIT: Reading a little further, even the units of the headline figure are a little odd, considering it quotes a figure in mN/kW, when in fact their tests only go up to 80W. It's a fair bit of extrapolation to go from 80W to 1000W...

Why, is it that much off the scale to assume that if you fit 10 of these devices together, you wouldn't get 10× the output of an individual one? Maybe there's some scaling effects if you make one big one, but linear upscaling seems valid to me.

If you're willing to believe that it's actually generating thrust in the first place, and that we're not measuring some unaccounted for side-effect.

[p1t1o]

My money is on: instrument sensitivity has been rising steadily, now we are getting tiny readings from nowhere that we couldnt detect before - is it from tiny environmental factors or newly discovered, ground-breaking physics?

I'll let you try out Occams razor on that one.

[Technical Ben]

Has anyone tried rotating the test device (including rig, sensors and entire building!), to confirm if this is directional to the earths magnetic field?

[NeverEnoughFuel!!]

33 minutes ago, Kerbart said:

Why, is it that much off the scale to assume that if you fit 10 of these devices together, you wouldn't get 10× the output of an individual one? Maybe there's some scaling effects if you make one big one, but linear upscaling seems valid to me.

If you're willing to believe that it's actually generating thrust in the first place, and that we're not measuring some unaccounted for side-effect.

Well this is basically what is driving me nuts! WHY THEY ARE NOT SCALING IT UP? As far as I know from some previous reading and interviews with inventor he stumbled upon Em drive while working on aiming devices/radars for ICBM's... is that technology so expensive? To re - purpose some old air force radar? Some old MRI medical aperture?

Lol... this reminds me of the documentary about how did Soviet union developed closed cycle rocket engines... make it/launch it/BOOM, make it/launch it/BOOM ... and so on for ten times until the first one didn't go BOOM ... A-haaaa ... it's time for a kickstarter people!

Edited November 8, 2016 by NeverEnoughFuel!!

[p1t1o]

9 minutes ago, Technical Ben said:

Has anyone tried rotating the test device (including rig, sensors and entire building!), to confirm if this is directional to the earths magnetic field?

Im not sure, but IIRC one of the most prominent tests did try the test with the thruster upside-down....and measured a force in the same direction as right-side up....

Edited November 8, 2016 by p1t1o

[Steel]

51 minutes ago, Kerbart said:

Why, is it that much off the scale to assume that if you fit 10 of these devices together, you wouldn't get 10× the output of an individual one? Maybe there's some scaling effects if you make one big one, but linear upscaling seems valid to me.

If you're willing to believe that it's actually generating thrust in the first place, and that we're not measuring some unaccounted for side-effect.

It's not that 10 of these wouldn't produce ten times the thrust of one, it's whether the same design scaled up to use 10 times the power would produce ten times the thrust. Considering how little understanding we have of how or even why these things work, it's not scientific to assume that just because a relationship is linear for a thruster using 40-80W that it will scale up if you build a thruster to use 1000 W or more

Edited November 8, 2016 by Steel

[Kerbart]

14 minutes ago, Steel said:

It's not that 10 of these wouldn't produce ten times the thrust of one, it's whether the same design scaled up to use 10 times the power would produce ten times the thrust. Considering how little understanding we have of how or even why these things work, it's not scientific to assume that just because a relationship is linear for a thruster using 40-80W that it will scale up if you build a thruster to use 1000 W or more

For NASA to be interested in this two things have to happen:

• It needs to work (a healthy amount of skepticism is warranted, “if it sounds too good to be true, it’s because...” etc)
• It needs to be useful

For the second point a simple “we have a lab model that produces 0.0001 N of thrust” isn't meaningful, especially not when followed by “when powered by a nuclear reactor.” So the measured output is scaled to something that is easily to understand, in this case N/kW. I'm sure it's easy to look up how many kW solar cells or RTG's produce, and from there on you can extrapolate how much thrust your EM drive can produce. I doubt the measurement was intended as a statement of we assume it will scale lineary, more of if you have x kW of power on board, you can have at least y N of thrust with this device. Which for mission planners is interesting to see if this device would be useful to them in the first place.

All, provided of course, it works as its inventor claims it does. That still remains to be seen though; looking forward to a cubesat test!

[magnemoe]

7 minutes ago, Kerbart said:

For NASA to be interested in this two things have to happen:

• It needs to work (a healthy amount of skepticism is warranted, “if it sounds too good to be true, it’s because...” etc)
• It needs to be useful

For the second point a simple “we have a lab model that produces 0.0001 N of thrust” isn't meaningful, especially not when followed by “when powered by a nuclear reactor.” So the measured output is scaled to something that is easily to understand, in this case N/kW. I'm sure it's easy to look up how many kW solar cells or RTG's produce, and from there on you can extrapolate how much thrust your EM drive can produce. I doubt the measurement was intended as a statement of we assume it will scale lineary, more of if you have x kW of power on board, you can have at least y N of thrust with this device. Which for mission planners is interesting to see if this device would be useful to them in the first place.

All, provided of course, it works as its inventor claims it does. That still remains to be seen though; looking forward to a cubesat test!

True, it's still to good to be true, however experimental data indicate that it works or that we are into something just as strange. 
The latest test is not the best version tested, version was selected because it eliminated error sources. 

You have something with 1/10 of an decent ion engine performance but no fuel use and no moving parts. Looks like it can be scaled down pretty well too.
Both deep space use, think dawn and satellite operations are obvious ones. 
Optimized engines will open new options depending on optimization level