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Registered Member #3118
Joined: Sun Aug 15 2010, 05:34AM
Location: Olney, MD
Posts: 8
so i thought of this a few years ago. has anyone tried making a multistage with pancake coils that are maybe 5mm thick? if you had 20 or so stages it could get powerful. i thought that because there are so many stages they only need 50J and because of that IGBT switching wont cost that much so there can be many stages. also because the coils are so thin the power gets very concentrated near the projectile greatly helping efficiency. also it might look really cool! of course i cant do this my self because i am unable to buy parts online.
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
I don't think this will work: Firstly IGBTs aren't cheap! Secondly I don't you could get enough induction from 50j over 20 coils to move the disk/armature. Thrid you would need a way to get the coils to fire in succession
I don't know too much about induction launchers so thats all I can say.
Registered Member #90
Joined: Thu Feb 09 2006, 02:44PM
Location: Seattle, Washington
Posts: 301
A single-stage pancake coil works well because the projectile is a flat aluminum plate that matches the size and shape of the pancake. The projectile rests flat on top of the coil putting all the windings in extremely close proximity, which is then repelled apart by induced currents in the plate's flat surface.
This arrangement will necessarily make the pancake coil launcher a single-stage device. Example picture here.
If you're thinking of using a cylindrical projectile (instead of a pancake) that passes through the middle of a pancake-coil-with-a-hole, then all those windings on the outside are far away from the projectile and become very ineffective. This is why the best coil shape for hole-in-the-middle multistage launchers always end up using very few layers of thickness.
Or maybe you have something else in mind? Attach some diagrams for us.
Cheers, Barry Grammar police: You don’t write "with baited breath" unless you specifically mean "a mouth full of worms."
Registered Member #3118
Joined: Sun Aug 15 2010, 05:34AM
Location: Olney, MD
Posts: 8
i was thinking more along the lines of a mass driver. if the coils are thin they can be placed very close to each other ( 2mm for sensor) so that the next coil could pull the projectile out of the previous one in the case of suckback. i thought this arrangement is better because it would be easier to get the projectile moving with only 2 or 3 stages (100-150J) rather than wast 1000J on the first stage. after its moving you can have the bigger stages to give it more energy slowly. yes Barry i am thinking of a cylindrical projectile thank you for reminding me about the outer windings i didn't think of that but i guess every design has its flaws.
P.S. GhostNull i have made an induction launcher that stuck a quarter into my ceiling with only 32J (5 camera caps). Quarters are great projectiles!
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
YES, but then because SCR can't be turned off (unless you build a v-switch but that requires another SCR and 2 capacitors per stage) you will need a capacitors for each stage and you will probaly loss efficiency because the coils would be turn on for longer than needed.
Barry, A reconnection coilgun might work in multistage: (second one down)
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new mega multistage coilgun
