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Hi, I'm designing coilgun and I have a problem which I'm not able to solve. So here's my question: How can I choose the best coil for my gun? Is there an equation to find the force of solenoid or other physical quantity which will allow me to compare coils? Thank you for your answers.
Registered Member #1906
Joined: Sat Jan 03 2009, 05:06PM
Location:
Posts: 39
I don't know much about the equations but Barry has got a couple of nice applets on his site that may help you find the optimal coil size for your needs. They don't deal with the force though.
Yes, I know Barry's site and his simulators but there isn't anything about chosing the best coil which will provide the best force (and what follows the best acceleration).
Registered Member #90
Joined: Thu Feb 09 2006, 02:44PM
Location: Seattle, Washington
Posts: 301
Tell me more about how you would define "best coil"?
This is an elusive definition, as the answer can range from electrical considerations to price and weight and ease-of-construction (think: liquid nitrogen?) and altogether a myriad of factors.
The reason we have no simple or analytic solution for force is that it's highly dependent on 3d geometry and material properties and applied current. For example, any coilgun of interest will be operating with enough current to enter the non-linear portion of the ferrous material's B-H curve. Furthermore, the material's response depends on its position in relation to the coil.
To really analyze and understand the "best" coil for any given situation, you need to run a finite-element magnetics modelling program, and program it to nudge the piece along its path while solving for forces at each step. There are some examples on my FEMM Modelling pages.
Cheers, Barry If you're not scared or angry at the thought of a human brain being controlled remotely, then it could be this prototype of mine is finally starting to work.
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
This question has been asked a bunch of times before, so you might get more information if you search for similar topics instead of waiting for people to repeat their posts.
Registered Member #14
Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383
There's not something as the "best coil" but the best coil for a given projectile and energy level exist and it is determined by calculation or experimental setup modulation.
Barry, thank you for tour exhaustive answer. I'll look closer at FEMM and your examples as soon as possible.
TheMerovingian, can you tell me more about calculating the best coil for a given projectile and energy level? I want to compare similar circuits with different coils to find the one which will provide the best acceleration of projectile.
Registered Member #14
Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383
There are some generic guidelines. Such as the lenght should be similar to projectile lenght, the external diameter as small as possible, the resistance and inductance chosen to have a pulse width compatible with your speed goal, etc.
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
Yes, the best you can do is make sims and get an aproximate coil design and optomise from there. It would be possible to design a perfect coil but I would require alot of time skills and expensive simulation software.
The best method is to estimate then trial and error from there.
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How can I choose the best coil?
