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I was also thinking about this, but never had tube to test it. I have a magnet from Bicycle Computer (tachometer), which is perfectly round, and I also have bigger magnet from some russian speaker, which is little weakess than smaller one. I can place foto if you want, it is about 5 and 13mm diameter. But how the hell you want to be sure it´ll be in right direction, when you fire? And... these magnets are made of something silver, maybe neodymium...
Registered Member #567
Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147
If you want to use neodymium magnets, I think you could coat it with some epoxy resin, to absorb part of the force and keep the shards from flying everywhere. The magnet will probably break regardless, but at least there won't be shrapnel.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
Using a magnet for a small coil might help, but for anything that would have an output worth building the fields produced by the coil will be orders of magnitude greater than that of the magnet, and actually can end up remagnetizing it.
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
I don't think so. A well-designed coilgun should avoid saturating the projectile, and even a not-so-well designd one shouln't saturate the projectile by orders of magnitude!
A nice side-effect of this permanent magnet coilgun would be that fact that you could "push" projectiles instead of "sucking" them, therefore avoiding the pulse-shaping trial and error to avoid suck-back.
Regarding the magnets: For gods sake, just look at any of the Wondermagnets-whatever web shops or even on eBay. There are lots of places selling cylindrical magnets, even I have 10s flying around even though it never occured to me they could be used for a coilgun.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
A nice side-effect of this permanent magnet coilgun would be that fact that you could "push" projectiles
Joe, you can ''push'' normal soft iron very well.
Once it is magnetized by coil's field, it will not be much different from magnet. Maximum flux density (2,2T) is also close to what neo magnet achieves.
In a multistage design, each coil is to be situated with opposite polarity than last one, so it uses the current magnetization of the projectile to accelerate and reverses it in process. Next coil does the same but vice-versa. Not much different from a transformer or motor operation.
Ideally you could use unlimited number of stages as long as you assure each coil gives equal volt-seconds to the projectile (which is difficult) to assure that projectile doesn't walk into saturation. Only problem is that with such a small max flux density, energy that can be transferred to the projectile in each stage is very low.
This was my understanding at least, and I think magnet would not do much except introduce large remanence losses. What I considered ideal reluctance projectile is soft material with highest possible saturation B.
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Magnetic Munition
