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A Hybrid of Coil and Rail gun Answered

So I said i'd throw this up in the comments section on Youtube not too long ago, and I don't like it when something easy and free doesn't happen.

This is some ideas and observations that have to do with coil guns (mostly). I'm in the process of finishing up several projects, so my resources are kinda spread out. I should have a prototyped coil gun finished in 2-3 weeks though, so if this doesn't clear things up, hopefully that video will. I should point out, I am a chemist with expertise in biochemistry, not electrical engineering.

Basically my idea is to combine a railgun and a coil gun for the expressed purpose of avoiding the pitfalls that a pure coilgun or a pure rail gun have. At present, none of the designs out there would be capable of competing with an actual gun. By mixing the two, i'm hoping to get something that might eventually be capable of doing so.

So.. I've included a very poor drawing (I'm not an artist). The barebones circuit is sketched in the lower right hand corner. The gun barrel, which is a piece of aluminum tubing split into two pieces to sever as a rail system, is sketched in the upper left, and again in the middle figure to show how to integrate the coil and rail system.

Looking at the circuit design, you can see that this starts off as a very basic capacitor-inductor circuit. The charge is purposefully allowed to trickle through the circuit until the coil reaches saturation and the capacitor(s) are charged.

When the trigger is pushed, the inductor side of the circuit has to dump into the rail system to complete the full closed loop.
Because of the ferromagnetic material (the brown stuff), the magnetic force persists for a while (that is to say, it has high reluctance). The ferromagnetic material does one other thing that is important here. It forces the middle of the coil to be far off center. The coil is pulling the projectile into the middle of the magnetic field, but that is not necessarily in the center of the winding. Adding ferrite, or other high reluctance material, towards the end of the barrel biases the field towards that end. 

At the same time that the coil stops getting current, the rail system become active. This allows a charge to pass through the bullet/projectile, and, even though the majority of the force is going to be caused by the inductive coil, the rail system allows an eddy current to setup in the bullet. This does several things.
First the bullet doesn't have to be iron, nickel, or cobalt. With a stray eddy current in the projectile, any conductive material will work. The advantage here is that once the current stops, the non-magnetic material stops being  to the magnetic field, preventing backwards acceleration of the projectile as it exits the barrel. 
Second, Rail systems and coil systems are not often used because they are perpendicular to one another, but, this can be used to put spin on the projectile, in a similar manner to rifling in a barrel. 

After the projectile is fired, the circuit is open, preventing excessive electrical discharge. 

My circuit design is really badly drawn... =T
if it needs more explanation please post up questions. 


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5 months ago

It’s cool that someone else thought about making a hybrid between a rail and coil gun although I never thought about rifling or making the bullet spin however i did think of what to make the bullet out of preferably i would use a coating of a sliver tungsten alloy around a synthetic ruby/sapphire core the reason being tungsten is very heat resistant and sliver is the most conducive metal so a combination of the two would be perfect for the job and the ruby or sapphire is because they are the same gemstone with a hardness of 9 plus rubys are made of aluminum the color is from a different oxide and only affects the color not the hardness without it the gem is colorless or clear but with the way i’m thinking of making the gem it will have some iron impurity’s making it slightly gray colored


7 months ago

Have you thought about stages rather than one single piece(for the rails and coils both), as this will allow for lower saturation time on the coils and possibly lower the back emf affect the projectile experiences from the coils. This should also require lower voltage for power the rail system as each stage is shorter than on your typical railgun device. Not sure how well it works still working on the first prototype.


4 years ago

Even I'm going to build a similar prototype soon. The coil should not be wound around the rails but on top of them. Refer to left hand rule and right hand grip rule. I don't think you can put a spin on the projectile this way. It's better to put the coil in series with the rails. My YouTube channel: