Making a Coilgun - Part 3: Reconsidering Everything

I reconsider my initial assumptions about how a coilgun should be made, and explain my new ideas for a novel coil geometry.

Disclaimer: I may earn an affiliate commission when items are bought through these links.

[homieboi]

It’s so incredible to me that this guy was willing to challenge the concept of a coil gun instead of attempt to perfect the pre existing designs that have flaws we’ve all been avoiding. I always wondered why we have to use capacitors when their discharge is so strange for this sort of application, and that a constant high current would do much better. However, I never thought of changing the coil shape to a curve following a log equation, but after seeing his results and considering his reasoning, it looks infinitely better than most modern designs. Great problem solving man, this kind of work is truly fascinating!

[peasant]

Excellent video. I appreciate the thorough analysis of the problem beforehand, instead of jumping right to building and testing stuff. It's what separates a good engineer from a bad one.

[rodrigotudancafernandez]

Keep it up, man! This channel is brilliant

[jamiemarsden]

@Andries Putter science is about taking constructive critisism in your theoretical ideas and turning that critisism into practicality as with anything theoretical comes practicality and without theory there is no practicality in science. (to think first is to apply ones knowledge and ideas and make all theory practical and logical) and where possible share knowledge thus advancing in our thought of theoretical application via the will to be practical. :) this is science my friend :)

[dalenassar]

Please explain if I am wrong, but at about timestamp 3:05 you draw a V vs T diagram of a capacitor discharge discharge over what you call "a CONSTANT load". Isn't your drawing the discharge over a resistive type load?? Shouldn't the discharge curve over a constant load usually linear? For instance, for a simple linear voltage regulator, don't you see a linear discharge at the input? I have done several computer simulations (in BASIC) of this kind of coil. I graphed the magnetic field for countless windings. I got the peak IIRC mag. field far beyond the coil center, but never got it past about 80% the coil start. Have you looked at the winding of what is called a (zeeman slower)?

[sketchysticks]

Can we make the bullet more conductive to the magnetic field? In ac induction motors you put grooves in the rotor can a similsr solution be made for coilguns?

[sporkeh]

I doubt this will be more efficient. Single stage coil guns have terrible efficiencies (1-2%), the only way to get a coilgun to be efficient is to use multiple stages, that way the degrading magnetic field caused when one coil is switched off is cancelled by an opposing field (in the correct direction) in the next coil. The magnetic coupling of coaxial coils with this geometry would be terrible.

[H...]

I think you're vastly over estimating the discharge rate of capacitors. At higher speeds (above 100 m/s), you're actually going to have the opposite problem. You wont have enough time for the current to build up and rise to it's maximum through the inductors (coils), before you have to switch it off abruptly when the projectile is in the middle to avoid suck back.
Secondly, the currents you're trying to force through these coils are way, way higher than batteries can handle, which is why people use capacitors. More current, gives you more force, more acceleration and a higher exit velocity.

I absolutely understand your reasoning behind the offset coil, but you won't get the constant acceleration you're expecting. It does give you a gradient which moves the projectile towards one end, but it is a less efficient/powerful way to do things. The low number of turns in the start results in a weak magnetic field there, and the magnetic field from the denser part of the coil at the other end is going to be weaker due to the inverse square law. Therefore you're better off with a more uniform, high density coils along the whole barrel that you commutate to move the projectile along, this makes full use of the length of the barrel to apply the maximum amount of force the whole way along.

Secondly, the voltage and current rating of a battery pack are almost unrelated. Your high voltage battery pack will likely not have the current capacity you're expecting, there's a reason people use capacitors.

Sorry, not trying to be negative, just wanted to correct some misconceptions before you sink too much time and money into some of these and then learn they wont work the way you expected. Coil guns are cool, and hard to make efficient/with high exit velocity, and I love seeing new approaches and ideas.

[joecitizen]

Good job ... I've been wiring up the same coil ... but for a lot bigger project ... as soon as I get my patent, I'll share the completed project.

[nissaarwz]

Hi bro, any updates? i am eagerly waiting for a new video for this Coilgun

[AnthonyAllenJr]

Amazing!! This is science, love it. You may need to patent some ideas soon.

[joshuabrand]

You possibly could have multiple discharge points in each conical coil, using a battery to provide a constant charge to the coil, with small light sensors integrated into each conical coil via an inner barrel layer (for the projectile) and an outer barrel to house the diodes and light receptors. Using the light diodes and light receptors to trigger each discharge as the projectile moves down the barrel and each successive conical coil. Using a battery in the stock to provide a small constant baseline voltage in the conical coils themselves, and two to four high voltage batteries integrated into the magazines to power the capacitors. That would probably allow you to use smaller capacitors. Especially if let's say for instance, you use nine capacitors per coil, three per discharge point in each coil (by making your coils in both sections and layers, two layers two be exact with the inner layer being comprised of three sections one capacitor per section, each section dividing the conical coil in thirds by length. And the outer layer providing the constant base voltage going the full length of the conical coil.) You could then use let's say (I'm not sure if you can find or make on but hypothetically) capacitors that are around four to five inches in length and eleven to thirteen sixteenths of an inch in diameter, with a high enough UF rating to handle a high voltage charge source. Then integrate them in semicircular bundles, three layers of three into the foregrip area one bundle under each conical coil to reduce the distance and wire length between the capacitors and the conical coils reducing your discharge delay (even though it's fractions of a second it should make a difference). Along with having a diode and light receptor trigger dedicated to each layer of each capacitor bundle for fine tuning of the system to further decrease any discharge delay. Using the battery in the stock to power the diodes and light receptors along with their accompanying trigger modules and the baseline primer voltage of the outer layer of the conical coils. Allowing the high voltage batteries in the magazine to be dedicated to charging the capacitors. As for your firing mechanism you could have the "breach and bolt assembly" slightly back away from the conical coils just outside of their area of effect, using high rpm electric motors to operate the bolt carrier and load the projectile into the breach, and use a reciprocating electric motor to act as a kicker and quickly shove the projectile into the conical coils field of influence. I hypothesize that what you would have in the end is something of a constant primed rapid pulsed discharged conical coil rifle, that could actually achieve firearm equivalency in muzzle velocity and range. And with further refinement possibly something more equal to if not greater than .50 BMG in velocity and kinetic force while using a lighter and cheaper projectile.You could also integrate railgun rails with a helical geometry into the inner barrel (along with the diodes and light receptors) and patch in the discharge system to the helical rails to make a hybrid system and impart spin stabilization to the projectile. Furthermore you can make your coils into a hybrid design in of themselves. By making the segmented inner layer of the coils conical, and each section in insulating paper (not much just enough to prevent any arcing of the charges between the components) and wrapping your outer layer of the coils in a more cylindrical geometry. The inner conical coil being the rapid pulse discharge system, and the outer layer being the lower voltage primer (that shuts off temporarily as the third discharge is triggered in each coil. While the helical rails in the inner (projectile layer) barrel also have their own dedicated battery integrated into the but stock with a set variable voltage switch so that when you squeeze the trigger it has an instant increase of voltage, with the pulsed discharge sections of each inner conical coil dumping their loads into the helical rails using micro inverters housed with the diodes and light receptors between the inner and outer barrel at each section of the segmented inner conical coils. Further increasing projectile velocity while imparting spin stabilization to increase range and accuracy.

[robertgissing]

I literally thought about this yesterday, thanks for doing this work!

[krisallen]

What about using a high capacity tazer to power the coils on off really fast or for more power output use the Subaru flyback or other vehicle spark coil for on off freq?

[_reddruid_]

It's been 4 years, but I'll give you a hint because I have an EMG, combine two magnets next to each other and force them to both turn on at the same time, but the other one turns off and a little slower than the first one, you can create your curve with the one you were showing and you don't have to make a cone coil

[blackebl]

Building a hobby gun at home and am at a juncture im not sure how to cross. Some people say go capacitor others say use inductors. Which one should I use for pre shot energy storage? Power supply isnt a problem. Just stuck there. Help?

[carlruffier]

When you speak of the barrel is the projectile going to travel through a rifled barrel. It seems you understand the electromechanical ideas but to be accurate it needs to travel the length of the barrel with rifling to put a spin on it to make it accurate. If you want to replace the chemical process with and electromechanical process it needs to be fast, accurate and generate speeds of at 1000 ft per sec which to me is the bottom speed. Let me ask you a question have you ever fired a real rifle to understand the foot-pounds involved in just a 40-grain bullet.

[guerrillaradio]

Seemed to be stronger in reverse. Remember, you're also accelerating the projectile from rest, which is it's point of greatest inertia. The greatest number of windings might actually do more good there if you're hooking it directly to a battery instead of capacitors.

[Potates]

I actually had this idea myself but i never actually put it into practice. Might try it on a larger scale in the future, and now i see one of the issues i should put a steel plate in the back.

[Plobq]

What if you used two capacitors on each coil, would it help keep a steady high energy output rather than a spike and fall? The second capacitor should give it another high energy output right as the first capacitor drops in output. One capacitor to pull the object in and one capacitor to push the object out.