What would it take to make my own EM Drive?

[cubinator]

So I did some research, and basically an EM drive works by bouncing microwaves around in a resonating cavity and it magically produces thrust. From a physics perspective, this is mind-blowing. But from an engineering perspective, it's quite a simple machine. The ones that have been made are basically just a hollow truncated cone made of a conductive material like copper or silver, with a hole in the side with a magnetron from a microwave oven. Turn on the magnetron and the Kraken pushes it a little harder on one end than the other, producing thrust. The thrust measured has been minuscule, but there is a mention on the official website (scroll to the very bottom) that if the cavity is superconducting, it would produce a lot of thrust. So basically, in order to do this, you need the cavity in the right truncated cone shape, made of a superconductive material, cooled to superconducting temperatures while it's being blasted with microwaves originally intended specifically for heating things up. That takes a bit of effort.

My idea would be to have the cavity made of a high-temperature superconductor like yttrium beryllium copper oxide, with another cavity surrounding it which is filled with liquid nitrogen which is continuously pumped through and refrigerated, as what is in there will quickly heat up from the magnetron's heat. In order to do this, I would basically have to make the cavity myself. I would do so using this method, but I'm not sure how i would manage to get a truncated cone out of that. Then I would have to make the outer shell out of something that retains heat and is airtight so that the nitrogen stays in and doesn't get heated up from outside. Then I would need a refrigeration system that would keep the nitrogen cold and thus keep the cavity cold. Also, I would need some liquid nitrogen.

So all in all that's kind of a lot, but it would be doable if I had a few thousand dollars to spare. I don't expect to be doing it anytime soon, but I'd just like to know how feasible it is. The non-superconducting version would be easy, just get some sheet metal and gut an old microwave. But the superconducting version would be much harder to do, but possible if I had the materials readily available, and it would produce really definite thrust that can actually be used for something if it works. What do you think?

 

 

[Scotius]

http://forum.nasaspaceflight.com/index.php?topic=38577.0

 

This is seemingly main hub for private efforts at building EMdrive ( mostly in garages ) People there reported some successful tests. But as of this moment no one attempted to build superconducting cavity.

[PB666]

The thruster causes electrons to build up in nodes inside the cavity. Never heard anything about the super conducting stuff.  Basically you need an rf generator that inserts near the juction if the cone and the resonator. 

Its not a drive until its proven to produce thrust in a stand alone state. 

If you have a microwave rf generator the nitrogen aint going to keep it cold for long. I don'think you need alot, these new graphite conductors may suffice. 

Edited December 7, 2015 by PB666

[K^2]

HTSC has pretty low critical field at LN temperatures. I'd wager, it will transition to normal as soon as you turn on the magnetron, making the whole thing work even worse than a good conductor like copper. If you want a superconducting cavity here, you need the sort of superconductors that are used in particle accelerator coils and medical MRI equipment. That means liquid helium cooling, keeping the superconductor at 2-4K.

Another thing to note is that you don't have flowing LN. That's not how you cool things with LN. It cools by evaporating, which means, all you have to do is submerge something in it, then make sure you keep the container topped off. Same with LHe. However, if you want to go down to 2K or so, you'll have to also reduce pressure in the chamber to drop boiling point to 2K. This requires very expensive hardware, which is why it's only used on particle accelerators, where they really need cavities to be superconductive.

Backing HTSC into whatever shape you need is fairly straight forward. I mean, in the way that it's not harder than just making HTSC. And that's an interesting project all on its own. There are a LOT of safety factors there, however. If you want to try it, make sure you understand all of the relevant precautions for both working with the oven you'd need to bake HTSC and for working with LN.

[cubinator]

7 hours ago, K^2 said:

There are a LOT of safety factors there, however. If you want to try it, make sure you understand all of the relevant precautions for both working with the oven you'd need to bake HTSC and for working with LN.

Yes, I realize that there's a lot of stuff that could get me hurt or killed working with radiation, chemical powders, furnaces, and super cold liquids. I would make sure I know what I'm doing before I actually do it.

[fredinno]

I have the answer, just put a microwave in a cool-looking box with a hole at one end! Now you have an EM Drive!

But seriously, EM Drives don't work anyways.

[PB666]

38 minutes ago, fredinno said:

I have the answer, just put a microwave in a cool-looking box with a hole at one end! Now you have an EM Drive!

But seriously, EM Drives don't work anyways.

Ten or so experiments to date suggest they work _on earth_. 

[PB666]

1 hour ago, cubinator said:

Yes, I realize that there's a lot of stuff that could get me hurt or killed working with radiation, chemical powders, furnaces, and super cold liquids. I would make sure I know what I'm doing before I actually do it.

I 've been burnt by liquid n2. Those cyroprotecting gloves dont work all that well, Its a deep long lasting pain (about 2 weeks) that feels like you have a bee sting about a half inch under the skin. 

Liquid n2 is excessive diificult to contain, it will crack most polyalkenes after several uses, dewer flask dont work all that well. If you try to run it through a line it boils and you have a vapor lock unless you place one end of the line under negative pressure.  You could coat the copper with a spray foam insulator, but then that degasses quite readily under experimental conditions and you could not test the result. 

The biggest and most obvious issue is that moving liq n2 in a copper line adds momentum to the system, so this cannot be calculated out, even if the inlet and outlet where on the same point of the axis, the boiling of the nitrogen in the evaporator coil will create a constantly changing differential momentum. You would actually have to cool the whole thing to the boiling point of nitrogen, which is problematic because the the nitrogen in the air would begin to precipitate on the device, not to mention all the moisture and higher boiling point gases, you would have to displace the air of the system with helium. 

'

[cubinator]

Theoretically I would use a very insulating material on the outer shell so that outside heat is not a problem. It would likely be vacuum-sealed and pressurized too if I can do it safely. If it works the way it's "supposed to" the thrust produced by the drive itself would be much more significant than the flow of nitrogen/helium which would work better but be way harder to deal with. 

8 hours ago, fredinno said:

But seriously, EM Drives don't work anyways.

This has not been proven nor disproven. The reason for this experiment would be to see if a superconducting cavity produces enough thrust for "terrestrial applications" as stated by the official site to avoid calling it "flying cars" like it would mean ***IF IT WORKS***
The thrusts that have been measured have been within experimental error, whereas the thrust from a superconducting drive ***should*** produce much more definite thrust, ***if*** we are seeing actual fuel-less thrust and not some other artifact of zapping materials with microwaves. Notice that there are a lot of "ifs." We really don't know what's going on with these things, but whatever it is, it's intriguing. That's why I'm interested in this. It's quite natural for humans to be interested in something that we don't understand, that's why we have learned so much. Because we choose to find out things anywhere from "what is on the other side of that hill" to "why do the planets move" to "is this machine producing thrust without consuming fuel?" It's questions like these that drive us, and in my opinion, it's ok if the EM drive is proven not to produce fuel-less thrust, because then we will have the new question of "what was causing those miniscule forces we observed?" And so there will always be another mystery to solve, and that is the beauty of science.

[PB666]

2 hours ago, cubinator said:

Theoretically I would use a very insulating material on the outer shell so that outside heat is not a problem. It would likely be vacuum-sealed and pressurized too if I can do it safely. If it works the way it's "supposed to" the thrust produced by the drive itself would be much more significant than the flow of nitrogen/helium which would work better but be way harder to deal with. 

This has not been proven nor disproven. The reason for this experiment would be to see if a superconducting cavity produces enough thrust for "terrestrial applications" as stated by the official site to avoid calling it "flying cars" like it would mean ***IF IT WORKS***
The thrusts that have been measured have been within experimental error, whereas the thrust from a superconducting drive ***should*** produce much more definite thrust, ***if*** we are seeing actual fuel-less thrust and not some other artifact of zapping materials with microwaves. Notice that there are a lot of "ifs." We really don't know what's going on with these things, but whatever it is, it's intriguing. That's why I'm interested in this. It's quite natural for humans to be interested in something that we don't understand, that's why we have learned so much. Because we choose to find out things anywhere from "what is on the other side of that hill" to "why do the planets move" to "is this machine producing thrust without consuming fuel?" It's questions like these that drive us, and in my opinion, it's ok if the EM drive is proven not to produce fuel-less thrust, because then we will have the new question of "what was causing those miniscule forces we observed?" And so there will always be another mystery to solve, and that is the beauty of science.

This will never result in flying cars, unless the car is flying around on mimas. It produces thrust on earth, we do not know why, in that sence it is a 'drive'. However it has never been shown to produce thrust in an environment like space. People seem easily to forget, this thing produces 10 times more thrust than pure EM 'drive', but thats not very much thrust at all, discounting the energy in reaction mass of most thrusters, thrusters like ion drives and VASiMR produce alot more thrust per emf, and even these could not produce a flying car.

No flying cars, no perpetual motion machines, none of that bs stuff, its simply a novelty that might give a long-lived science ship the ability to travel to multiple targets in the system, it might even allow an orbiter around pluto, thats pretty much the limit. 

[cubinator]

11 minutes ago, PB666 said:

This will never result in flying cars, unless the car is flying around on mimas. It produces thrust on earth, we do not know why, in that sence it is a 'drive'. However it has never been shown to produce thrust in an environment like space. People seem easily to forget, this thing produces 10 times more thrust than pure EM 'drive', but thats not very much thrust at all, discounting the energy in reaction mass of most thrusters, thrusters like ion drives and VASiMR produce alot more thrust per emf, and even these could not produce a flying car.

No flying cars, no perpetual motion machines, none of that bs stuff, its simply a novelty that might give a long-lived science ship the ability to travel to multiple targets in the system, it might even allow an orbiter around pluto, thats pretty much the limit. 

Taken directly from the official EM drive website:  "The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications. "

That sounds like flying cars to me. Again, I cannot stress enough that I am by no means assuming this thrust really exists. It's just an interesting and intriguing possibility. And I think an orbiter around pluto or a flying Mimas car is pretty darn cool too. And if it can fly on Mimas, I think it's just a simple case of "moar booster" to lift something on Earth. And the TWR would be constant as it doesn't have anything to do with atmosphere. If you lift something with 1 drive on Mimas, well you just need 150 drives to lift the same thing on Earth.

[PB666]

17 minutes ago, cubinator said:

Taken directly from the official EM drive website:  "The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications. "

That website is complete BS, and they are just trying to spin a buck. 

First the force they are talking was demnstrated 80 years ago, the company didnt even exist in. 

[Nuke]

i think i would opt for a woodward drive. all you really need is a 4 phase rf power supply and a few passive components found in any electronics hacker's junk drawer.

[KerbonautInTraining]

Using these for anything other than Dawn-like operations is kind of pointless.

The website cconveniently forgets that these engines are spewing tons of microwave radiation. Obviously the best place to fire them is in a populated city, even better if you use them to pass over crowded streets in a flying car.

(Note that any aggression is pointed solely towards the aforementioned website)

[Mazon Del]

Actually they don't "spew tons of microwave radiation", that is why a lot of people hate the concept of the EMDrive. None of the energy leaves the engine, so it shouldn't move. And yet...it does.

HOWEVER! As they say repeatedly on the NASA forums, if you are looking to make a homebrew drive, make EVERY effort to be safe, a leaky waveguide can seriously harm or blind you.

[SomeGuy123]

50 minutes ago, KerbonautInTraining said:

Using these for anything other than Dawn-like operations is kind of pointless.

The website cconveniently forgets that these engines are spewing tons of microwave radiation. Obviously the best place to fire them is in a populated city, even better if you use them to pass over crowded streets in a flying car.

(Note that any aggression is pointed solely towards the aforementioned website)

Also, even if the Kraken is pushing on em, they probably still obey conservation of energy.  Technically, "hovering" in midair must consume a vast amount of energy because you're actually producing as much work as the mass of the vehicle falling over 1 second times mgh.

At least, I think so...

And one could reasonably expect that even if it works, the force per joule should be a whole lot less than a rotor turning in the atmosphere.  TLDR, it's not going to be possible to fly at all without a ridiculous power source.

[YNM]

Probably you'll need the magnetron, the cavity, and the liquid nitrogen. Or you can drop the liquid nitrogen.

Working/ not working aside, maybe asking some enthusiast to have one device sent to space would be a great idea : telling whether something works at the actual condition.

 

 

[Kerbol Macrosystems]

I recommend you take it slow of you're going to try this. Test your ability to handle the different components first. Build a room temperature EM drive. Test it to make sure you're not spitting microwaves all over the place. 

Read a lot on material handling safety. The Chemical Safety Board Http://www.csb.gov and the American Institute of Chemical Engineering's Center for Chemical Process Safety http://www.aiche.org/ccps might point you at some chemical safety practices. Our at least show you how horribly wrong playing with chemicals can end up. You're going to need special gloves, the right kind of respirator, and a lot of other personal protective equipment. 

Once you're there try making any ceramic in your lab oven before you make toxic ones. 

If you really insist on getting liquid nitrogen try doing stuff in open air first. Freeze some Rose petals. If you get your ceramic just pour liquid nitrogen over it and play with a magnet.  

Trying to contain liquid nitrogen is horribly dangerous. The American Society of Mechanical Engineers publishes the Boiler and Pressure Vessel Code. You're going to need to build your cooling jacket to those standards. Nitrogen expands a lot on evaporation, which means that it can throw shrapnel really far. The BPVC is all about dealing with pressurized gasses and liquids. Don't use carbon steels. They can stress crack under -20F. You'll need cryogenic rated valves. Remember to stress relieve your equipment. It's about to go under a LOT of thermal stress. 

Also nitrogen thinks your normal refrigerator is really hot. The refrigerant used doesn't get cold enough. Plan on going through lots and lots of nitrogen. You'll need to let it boil to atmosphere so that everything stays as cold as the LN2 boiling point. Don't let it evaporate inside. The nitrogen will chase all the air out of the room and you'll asphyxiate.

You're getting into the realm where there's no cheap way to run your experiment safely. Working with toxic powders requires a bunch of specialized gear. Even if you don't die you could end up with the EPA wondering why there is a toxic spill in a residential neighborhood. Working with cryogenics requires a whole different set of specialized equipment. Working with pressurized cryogenics requires even more specialization. You're in for a lot of work before you even think about assembling all these components into an EM drive. 

[wumpus]

Note:  In the almost certain case that "the EM Drive" doesn't really work, you can always build an EM drive by firing a laser/radio/EMwave of your choice as a rocket propellant.  Photons have mass and momentum, you can use them as thrust (you can also use a ground-based laser and us that to push up a launcher).

You could also rig up a cyclotron for arbitrarily high ISP.  Note that such a thing would have insignificant thrust, so presumably would be on a multi-century sleepership and wouldn't be started until the ion thrusters ran out of fuel (and then run for a few centuries).  Or maybe you just wanted something that would take a Voyager record into intergalactic space (after a few millenia).

[cubinator]

It was just an idea, it's very improbable that I would actually play with these things until I become a rocket scientist or something. It might be a project for years from now, but at this time I don't have what I'd need for any major experimentation. I do think that somebody should rig up one of these things to a small satellite, launch it into LKO LEO, and fire it up just to see if it really runs. That seems to be just about the only way to prove/disprove it, as all the Earth-based tests have been so controversial.

[EladDv]

you cant make it period, you could possibly make a device that shoots electromagnetic waves towards a conical metalic surface but i dont see what would that accomplish. 

Now assuming this device works and actually produces thrust we are going to need to invent totally new theories about either momentum or electromagnetism which (while totally possible) is extremely unlikely that would happen, plus none of the "experiments" done so far have been peer-reviewed and most of them are inconclusive anyways so really i wouldnt hold my breath to some guy inventing a real life kraken drive

[PB666]

1 hour ago, EladDv said:

you cant make it period, you could possibly make a device that shoots electromagnetic waves towards a conical metalic surface but i dont see what would that accomplish. 

Now assuming this device works and actually produces thrust we are going to need to invent totally new theories about either momentum or electromagnetism which (while totally possible) is extremely unlikely that would happen, plus none of the "experiments" done so far have been peer-reviewed and most of them are inconclusive anyways so really i wouldnt hold my breath to some guy inventing a real life kraken drive

Let the 6 figure income physicist figure it out, the engineers job is to optimize and innovate. However as  i previously one cannot optimized if boiling liquid nitrogen creates milliNewton noise and you are optimizing in the micronewton range. Look for passive cooling methods. 

Is standard uWave so inefficient that the transformers need to be superconducting?

[A35K]

I don't get why people are always so skeptical about these new things. Sure, they might seem to violate laws of physics, but maybe there is more to learn about? I myself don't think these things will be able to produce enough thrust for flying cars etc., but IF they work in space, it would revolutionize space travel. And also, aren't there other speculated types of "reactionless drives", such as the Quantum Vacuum Plasma Thruster? I know all of these are not proven to work, but they are a starting point... And anyway, aren't photons technically supposed to have momentum, due to wave-particle duality? So wouldn't a thrust generated by massless photons NOT disobey the conservation of momentum? What about solar sails?

Edited December 19, 2015 by A35K

[cubinator]

The drives tested have had cavities made from conductive materials like copper or silver. This allows the microwaves to bounce around in the cavity and increasing the net forces inside. The conductive cavities have a low "Q," basically the amount that it resonates. It's like a bell that you are trying to ring as loudly as possible. Apparently, if the cavity was superconducting, it would increase the thrust enough to do something with on Earth. That's the point of making it superconducting, because then the thrust (if working as expected) would lift the thing right off the ground. That would totally remove the "experimental error" factor and prove the device working (or not).

The other way to prove/disprove it definitely is to stick a standard non-superconducting one on a satellite and try to fly it to the Mun Moon. That should be fairly easy to do, all it takes is someone to put it on a cubesat or something. If no one does it, I'll become an astronaut and toss the satellite out the airlock myself if I have to. The people in charge are just too skeptical right now. Someone needs to do it.

[KerbonautInTraining]

40 minutes ago, cubinator said:

(Lotsa stuff)

The other way to prove/disprove it definitely is to stick a standard non-superconducting one on a satellite and try to fly it to the Mun Moon. That should be fairly easy to do, all it takes is someone to put it on a cubesat or something. If no one does it, I'll become an astronaut and toss the satellite out the airlock myself if I have to. The people in charge are just too skeptical right now. Someone needs to do it.

The problem is that it's very expensive to launch stuff into orbit. (Note that this thing wouldn't be small enough to be a cubesat) There is a very real possibility that it won't work at all. Until we're reasonably certain that it will, there's no sense in launching one up. You'd have to launch it into a pretty high orbit too, as the thrust could be small enough that it's overshadowed by atmospheric drag.

I'm just stating why we haven't done it yet, not saying we shouldn't do it.