Author Topic: NASA released peer reviewed study on the EM drive  (Read 956 times)

Offline Semnae

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Offline Remak

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Re: NASA released peer reviewed study on the EM drive
« Reply #1 on: November 21, 2016, 05:54:27 am »
Could you summarize what it says and why it is exciting? I tried to read the introduction but didn't really understand much of it :(. So I didn't try to read the rest

Offline Tiffanys

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Re: NASA released peer reviewed study on the EM drive
« Reply #2 on: November 21, 2016, 06:27:13 am »
This is the summary:
Quote
It was previously reported that radio-frequency (RF) resonant cavities generated anomalous thrust on a low-thrust torsion pendulum [1,2] in spite of the apparent lack of a propellant or other medium with which to exchange momentum. It is shown here that a dielectrically loaded, tapered RF test article excited in the transverse magnetic 212 (TM212) mode (see Fig. 1) at 1937 MHz is capable of consistently generating force at a thrust-to-power level of 1.2±0.1  mN/kW with the force directed to the narrow end under vacuum conditions.

Basically, it works.

This should be more digestible for you: http://www.sciencealert.com/it-s-official-nasa-s-peer-reviewed-em-drive-paper-has-finally-been-published

Offline Semnae

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Re: NASA released peer reviewed study on the EM drive
« Reply #3 on: November 21, 2016, 07:05:48 am »
Long story short, the EM drive is a propulsion system that has long been thought to be impossible because it appears to break Newton's Third Law of Motion. The Third Law of Motion states that for every action there is an equal and opposite reaction. That means in order for thrust to be produced in one direction, some force must be applied  in the opposite direction. The EM drive uses microwaves bouncing around a conical chamber to produce continuous thrust with no propellant. Scientists have not been able to discern why bouncing microwaves around in a conical chamber produces thrust. It's a mystery which wasn't taken seriously for years because everyone thought it was a hoax.

The existing EM drive prototypes produce very little thrust, but this still has major applications in space. Like the lightsail, it can provide continuous thrust without the need for the craft to carry any heavy fuel. It has been suggested that an EM drive could reduce the time and cost of traveling to Mars dramatically
« Last Edit: November 21, 2016, 07:21:54 am by Semnae »

Offline Burkingam

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Re: NASA released peer reviewed study on the EM drive
« Reply #4 on: November 21, 2016, 07:58:23 am »
This is really weird. Either the NASA somehow managed to reproduce a hoax which would be really strange or they just confirmed a hypothesis which will require major changes in our understanding of basic physics in the future.
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Offline Tanis

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Re: NASA released peer reviewed study on the EM drive
« Reply #5 on: November 21, 2016, 02:52:21 pm »
IF it can be replicated a few more times, then I'm rather hopeful for some future space exploration.

It will also be kind of cool to see, if it's true, how this will change our understanding of the universe.

Offline Krudda

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Re: NASA released peer reviewed study on the EM drive
« Reply #6 on: November 21, 2016, 11:13:55 pm »
This is really weird. Either the NASA somehow managed to reproduce a hoax which would be really strange or they just confirmed a hypothesis which will require major changes in our understanding of basic physics in the future.
Oh, but isn't our understanding of the laws of physics near-perfect? You don't mean to say we don't actually know anything? Noooooo.
</sarcasm>


So can we use this for other things like trains? Or even hyperloop one upgrades?

Offline kitamesume

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Re: NASA released peer reviewed study on the EM drive
« Reply #7 on: November 22, 2016, 03:16:01 am »
So can we use this for other things like trains? Or even hyperloop one upgrades?

nope, just auxiliary thrusters for spacecraft voyage.

the issue here is that, the thrust is on a millinewton scale, too microscopic for any serious propulsion.
in comparison, a single boeing 777 engine has 138 meganewtons of thrust.

Offline capnmorgan

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Re: NASA released peer reviewed study on the EM drive
« Reply #8 on: November 22, 2016, 03:34:56 am »
Maybe with propulsion like this we will see more micro satellites for observation as well as communication.  It might also reduce the light pollution for observers with lower powered telescopes.  Smaller surface areas reflecting light from the sun, that kind of thing. 


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Offline kitamesume

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Re: NASA released peer reviewed study on the EM drive
« Reply #9 on: November 22, 2016, 03:37:09 pm »
Maybe with propulsion like this we will see more micro satellites for observation as well as communication.  It might also reduce the light pollution for observers with lower powered telescopes.  Smaller surface areas reflecting light from the sun, that kind of thing. 

only if this thing didn't suck up so much power.

at the moment NASA's test unit is at ~7 millinewtons per kilowatt.

Offline Semnae

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Re: NASA released peer reviewed study on the EM drive
« Reply #10 on: November 22, 2016, 08:09:38 pm »
So can we use this for other things like trains? Or even hyperloop one upgrades?

nope, just auxiliary thrusters for spacecraft voyage.

the issue here is that, the thrust is on a millinewton scale, too microscopic for any serious propulsion.
in comparison, a single boeing 777 engine has 138 meganewtons of thrust.

only if this thing didn't suck up so much power.

at the moment NASA's test unit is at ~7 millinewtons per kilowatt.

You are forgetting that these are prototypes. They've not even begun to try to optimize the energy to thrust ratio. They don't know how the thrust is being produced, so optimization is going to be a long process of trial and error to see how different modifications effect the energy:thrust ratio. We have absolutely no idea what a fully optimized and upscaled EM drive could do.

Offline Tiffanys

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Re: NASA released peer reviewed study on the EM drive
« Reply #11 on: November 22, 2016, 08:40:00 pm »
Heck, we don't even understand how it works. We can't begin to optimize it, potentially even improve it, until we do understand how it works. Understanding it could open entire new areas of physics we didn't think possible. I mean it's possible once we do understand how it works that we could make it work with gamma instead of microwave, or any number of other things.

Offline kitamesume

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Re: NASA released peer reviewed study on the EM drive
« Reply #12 on: November 22, 2016, 09:00:39 pm »
You are forgetting that these are prototypes. They've not even begun to try to optimize the energy to thrust ratio. They don't know how the thrust is being produced, so optimization is going to be a long process of trial and error to see how different modifications effect the energy:thrust ratio. We have absolutely no idea what a fully optimized and upscaled EM drive could do.

i know, they had already conducted simulations with regards to it's efficiency.
they've pretty much concluded that it has higher efficiency at higher power inputs.

https://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/

Quote
Dr. White’s computer analysis also shows that increasing the input power focuses the virtual particle flow from near omnidirectional at the low powers used in the NASA experiments, to a much more focused jet like beam at the higher power (kilowatts as compared to less than 100 Watts) used in the UK and China experiments.

The simulation for the 100 Watts input power (as used in the latest tests at NASA) predicted only ~50 microNewtons (in agreement with the experiments) using the HDPE dielectric insert, while the 10 kiloWatts simulation (without a dielectric) predicted a thrust level of ~6.0 Newtons.  At 100 kiloWatts the prediction is  ~1300 Newton thrust.

The computer code also shows that the efficiency, as measured by the thrust to input power ratio, decreases at input powers exceeding 50 kiloWatts.

the only issue with this regard is that to generate 10KW ~ 100KW of power it also requires a huge generator.

Offline Semnae

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Re: NASA released peer reviewed study on the EM drive
« Reply #13 on: November 23, 2016, 02:39:06 am »
Heck, we don't even understand how it works. We can't begin to optimize it, potentially even improve it, until we do understand how it works.

That's not entirely true. While understanding how it works would certainly aid in the optimization process, it's not required. Remember, we used and improved upon hi-temp superconductors for almost 30 years without understanding how they worked. Sometimes technology outpaces Science.
« Last Edit: November 23, 2016, 02:47:35 am by Semnae »

Offline Bozobub

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Re: NASA released peer reviewed study on the EM drive
« Reply #14 on: November 26, 2016, 04:25:22 am »
nope, just auxiliary thrusters for spacecraft voyage.

the issue here is that, the thrust is on a millinewton scale, too microscopic for any serious propulsion.
in comparison, a single boeing 777 engine has 138 meganewtons of thrust.
Absolutely false, re; "auxiliary" thrusters, vs. "primary".  Why?  Three reasons:
- You don't have to use just one engine.  Why not 100? 1000? 10,000?  And so on...
- You don't need reaction mass at all, just power.  Enough solar panel acreage, for example, and you could flit about the Solar System indefinitely.
- Constant acceleration is far more important in almost all cases than maximum thrust, when in free fall.  With constant acceleration, no matter how tiny, you also don't have to take lowest-energy orbit paths any more, which is HUGELY important to space exploration, travel, and development.

Ion thrusters, while distinctly more powerful, still have very low thrust (less than a milligee is common), yet are expected to make trips to Mars much faster and safer.  In fact, if you could strap together enough of these to achieve 1g of constant  thrust, you could get to Proxima Centauri in 11 years or so, subjective time (time dilation effects would be pretty strong, though, meaning 50+ years would have passed on Earth), assuming a flipover at the halfway point for deceleration.

That's not entirely true. While understanding how it works would certainly aid in the optimization process, it's not required. Remember, we used and improved upon hi-temp superconductors for almost 30 years without understanding how they worked. Sometimes technology outpaces Science.
Absolutely true!  A good, lower-tech additional example is the fact that we understood how to make glass, and improve upon it in innumerable ways, long before we truly understand anything about the stuff.  No one knew WHY glass was transparent, for example, but they damn sure learned how to make superior optical glass =) .
« Last Edit: November 26, 2016, 05:20:29 am by Bozobub »

Offline Mistgun_Zero

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Re: NASA released peer reviewed study on the EM drive
« Reply #15 on: November 26, 2016, 08:49:15 am »
So can we use this for other things like trains? Or even hyperloop one upgrades?

nope, just auxiliary thrusters for spacecraft voyage.

the issue here is that, the thrust is on a millinewton scale, too microscopic for any serious propulsion.
in comparison, a single boeing 777 engine has 138 meganewtons of thrust.

The measurement of the EM drive is in thrust-to-power ratio. A totally different form of measurement. That type of measurement is not done (cannot be done? I looked around on net, didn't find much stuff) for other type of systems. In short, 1.2±0.1  mN/kW is pretty huge number when to it comes to fuel-less drives. I think the light sail was around 90mN/kW.

 In space, it can mount to quite a computational quantity if done right.
« Last Edit: November 26, 2016, 09:24:51 am by Mistgun_Zero »

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Offline Bozobub

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Re: NASA released peer reviewed study on the EM drive
« Reply #16 on: November 26, 2016, 09:12:09 am »
It's not "fuel-less", per se, it's reaction mass-less.  You still have to power it in some way, although again, solar panels might be sufficient.  But yeah, you're mostly right, anyway.

The more interesting uses, however, would involve having a nuke plant, or at least a large radioisotope thermal generator (with today's tech, that is).  You could then use these buggers in many way you couldn't, using solar power, such as the night side of any planetary mass.
« Last Edit: November 26, 2016, 12:33:26 pm by Bozobub »

Offline kitamesume

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Re: NASA released peer reviewed study on the EM drive
« Reply #17 on: November 26, 2016, 10:41:46 am »
thrust-to-power ratio is relatively common though.
an engine's performance is measured in horsepower, and their capacity to provide useful thrust.


also power is not unlimited, sure you can provide 10KW~100KW of power, but how massive of a power source is that?
the issue here is whether the thrust gained from 10KW~100KW be enough to propel that enormous mass.
furthermore, the technology doesn't exist yet, an RTG that can supply 10KW+ doesn't exist to date.


so far these propulsion devices are mostly aimed for cruising propulsion, e.g. its to maintain a constant speed.
these devices simply doesn't provide enough thrust for accelerating a payload.
« Last Edit: November 26, 2016, 10:48:31 am by kitamesume »

Offline Bozobub

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Re: NASA released peer reviewed study on the EM drive
« Reply #18 on: November 26, 2016, 12:25:44 pm »
so far these propulsion devices are mostly aimed for cruising propulsion, e.g. its to maintain a constant speed.
these devices simply doesn't provide enough thrust for accelerating a payload.
Absolutely false.  You are, apparently, stuck thinking how it is at the bottom of a gravity well, in a thick atmosphere.  That's simply not how it works in free fall, in a vacuum.

First off, you don't need to "maintain" speed in a vacuum, except vs. other acceleration vectors.  In other words, the solar wind, for example, makes a difference, albeit very small for a non-light sail craft, so heading directly into it would decelerate your craft somewhat (although less than the acceleration given here by a long shot, much less the Sun's gravity), but all in all, if you push an object in space, it will take a VERY, VERY long time to decelerate from "friction" with the vacuum.  We're talking millions of years from a single push by a human hand, assuming the object doesn't fall into a gravity well or somesuch.

Second, these low-impulse engines provide plenty of thrust to accelerate a payload.  As I mentioned above, an ion thruster has, on the average, under a milligee of acceleration (25-250 millinewtons of thrust).  That is projected to enable trips to Mars in 70 days or less!  Even the tiniest delta-V adds up, when applied indefinitely over time in an almost completely frictionless medium ("hard" vacuum).  In fact, as soon as you can apply ANY sustained thrust, no matter how small, you are no longer confined to least-energy orbits on interplanetary trips, as chemical rockets certainly would be.

The power densities required for LARGE amounts of acceleration from either "EM" or ion thrusters would be very difficult to satisfy, certainly, and you'd never be able to use them for launching from the bottom of any major gravity well, but that's also not particularly necessary.  Solar power can work (although the inverse-square law is a problem) but there are other solutions, such as fission power, that are certainly technically (although not necessarily socially or politically) feasible.  And you simply don't try to launch from a planet's surface using these types of thrusters ^^' .

NASA isn't researching these techs for giggles, you know; they're FAR more useful and efficient for deep space exploration than chemical thrusters ever will be; plasma and ion thrusters are already in use for this very reason.  The added bonus of ZERO reaction mass requirements for EM thrusters makes them even more useful; for instance, it makes interstellar travel suddenly quite possible, assuming you can solve the life-support side of that equation :P .
« Last Edit: November 26, 2016, 12:35:12 pm by Bozobub »

Offline kitamesume

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Re: NASA released peer reviewed study on the EM drive
« Reply #19 on: November 26, 2016, 12:53:26 pm »
you're forgetting the fact that space is riddled with gravity fields from other planets and stars, mind you even a small amount of gravity would cause you to accelerate backwards.
these gravity fields are in fact enormous, the sun in particular has a field that reaches as far as the furthest orbiting object around the sun, namely the Oort Cloud.

you need enough thrust to not get pulled back or be decelerated by those gravity fields, and this engine is sufficient for that.
« Last Edit: November 26, 2016, 01:11:59 pm by kitamesume »