Tuesday, June 19, 2007

Researchers propose electric jet engines powered by superconducting magnets

Y'know, you sometime wonder if people have thought of something through before they propose it.

These researchers are proposing that aircraft can function more efficiently using superconducting turbines, which are powered by superconducting magnets. I'm not kidding you.

A superconducting magnet, however, would be much more efficient and powerful for its size. When chilled to 77 kelvins (–321 degrees Fahrenheit) or colder, so-called high-temperature superconductors such as the ceramic YBCO (yttrium barium copper oxide) begin to carry electricity without resistance, which produces a strong magnetic field without wasting energy.

Just because YBCO becomes a superconductor at liquid helium temperature does not mean all the problems are solved. It is a Type II superconductors, which means that there will be magnetic vortices migrating all over the place when it is within a magnetic field of sufficient strength. This diminishes it's "zero conductance" property. Furthermore, the reason why these high-Tc superconductors are not used in all those superconducting magnets that are being installed at the LHC is because they can't tolerate high magnetic fields because the low supercurrent density tends to quench superconductivity at sufficiently high fields.

But more importantly, they seem to ignore the fact that (i) you have to carry the cryogenics and (ii) you have to maintain the cryogenics. This adds weight AND require extra power consumption. Did they take this into account when they estimated all of these "efficiency"?

To be fair, I should read the paper they published rather than rely on some silly news report, especially from Sci-Am that lacks any exact citation to it. So I'll try to get a hold of it when see if I will change my mind afterwards.



Anonymous said...

Wow, it looks like you should go to the library and get a good and recent book about high temperature superconductivity. Most of your statements about material are wrong. Read the paper published in IOP Superconductor Science and Technology, try to understand what's in it and come back to discuss the results.

ZapperZ said...

Would you like to list out all of the things that I said that was wrong?

I used to work in high-Tc superconductivity. In fact, I studdied the BSCCO family pretty well using both tunneling and angled-resolved photoemission spectroscopy.

My question about carrying the cryogenics can't be wrong. I mean, how else are they going to cool the damn thing? Furthermore, the vortex migration is a BIG deal. Please spend a lifetime trying to fabricate materials that can pin those vortices.

I will admit that I know very little about what is involved in a "superconducting turbine". I have found this paper but haven't printed it out yet and read it closely. I haven't changed my mind after reading the abstract.


Anonymous said...

On the subject of maintaning the cryogenics it might be possible to start the cryogenics on the ground which would start the super conductors. Which in turn you might be able to use that power to power the cryogenics.

live said...

hey, i know this will catch you by surprise, I've been gathering information on this subject for two years now and guess what? I've successfully developed feasible concepts on how to get rid of the combustion chamber and replace it with an 'heat generator.' the rest remaining the same, in a jet engine. Its simple actually. The three distinct stages in a jet engine will be powered by three separate electromagnets with independent power features. I particularly want to talk about the compressor section. I've modified it in such a way that the low pressure, the high pressure and the intermediate compressor stages can spin at different speeds or at a predetermined spinning ratio because the electro-magnet powering them has concentric shafts. for the combustion chamber, I've placed a heat generator. it is cylinder shaped with tunnels inside and each tunnel has a moving valve to and from end to end. now, I've placed a number of these heat generators into where we have the combustion chamber. The heat generator will be, like all other sections, computer controlled. The devil is in the details.

Trevor said...

I've made a small prototype that works, producing air thrust from battery (LiPo) power only.

I'm working on improving the efficiency, plus the problem that it won't start unless air is moving through the vent. Once started, it runs surprisingly well. There is significant thrust from the unit, I was very surprised. I'm not using a turbine, there are no moving parts.

I need to generate almost 1k thrust per Kilowatt, which is achievable very soon.

I'll build a larger version and test it on the roof of my car. This will enableme to measure thrust output and to be able to get the jet up to higher speeds, when it will become far more efficient.

I intend that it can be used in an aircraft. A small jet could be converted, provided that I can get batteries to replace the fuel weight.

As the unit is only one tenth the weight of a conventional jet, there are also some weight savings on removing the existing engines.
My engine has to be underslung, in the higher pressure air underneath the wing. This should be OK for car testing.

As I say, the main problem to solve is that it needs air movement of approximately 1 metre per second in order to start. Once this is achieved, there is no warm up and full throttle can be applied right away.