I want to know the pros and cons of hand held rail guns versus coil guns. They will be given to infantry who can easily lift the weapons. If need be they could have twice the strength of a normal human via cybernetic enhancements. What would be the various pros and cons, especially in rough terrain?
In short (links to follow as I find time to put them in).
Coil guns (aka Gauss guns)
Have a higher max projectile velocity. Powerful switches alternate the electromagnetic poles in the drive coils as the projectile passes through the coils. This requires high voltage, high amperage, high speed electrical switches. Researchers have been trying to build these for decades with only moderate success.
is a type of projectile accelerator consisting of one or more coils used as electromagnets in the configuration of a linear motor that accelerate a ferromagnetic or conducting projectile to high velocity.1 In almost all coilgun configurations, the coils and the gun barrel are arranged on a common axis.
Coilguns generally consist of one or more coils arranged along a barrel, so the path of the accelerating projectile lies along the central axis of the coils. The coils are switched on and off in a precisely timed sequence, causing the projectile to be accelerated quickly along the barrel via magnetic forces. Coilguns are distinct from railguns, as the direction of acceleration in a railgun is at right angles to the central axis of the current loop formed by the conducting rails. In addition, railguns usually require the use of sliding contacts to pass a large current through the projectile or sabot but coilguns do not necessarily require sliding contacts.2 Whilst some simple coilgun concepts can use ferromagnetic projectiles or even permanent magnet projectiles, most designs for high velocities actually incorporate a coupled coil as part of the projectile.
The force the projectile leaves on the weapon is it attempts to compress the coils (you'd get recoil similar to a normal weapon).
Magnetic fields are not inherently dangerous to people as long as they don't have magnetic metals on their person. Other than the difficulties with switches, a coil gun is much more suitable for use by unprotected humans (e.g. infantry):
Video at link: Man portable coil / gauss gun
Are much easier to build from a technological perspective. Current runs down one "rail" through the conductive base of the projectile and back up the other rail. This is the brute force method of electromagnetic projectiles.
A railgun is an electrically powered electromagnetic projectile launcher based on similar principles to the homopolar motor. A railgun comprises a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail.
The forces applied to the railgun try to rip the rails apart. The recoil from the projectile also supplies a recoil like a chemical slug thrower.
Each rail conducts high voltage and amperage current. Touching or getting close to one of the rails would be exceedingly dangerous. This weapon is probably not suitable for infantry use.
While using rail or coil guns as infantry small arms is problematic (due to the various issues already discussed), there may be a place for railguns as a man portable anti tank weapon.
Current ATGM's generally use shaped charge warheads to actually penetrate the armour (the rocket motor just gets it there), and various techniques have been developed since WWII to defeat these types of warheads, including spaced armour (such as the "cages" around modern tanks), explosive reactive armour (the brick like devices attached to the outside of most Russian tanks) and even counter missiles like the Russian "Arena" or Israeli "Trophy" systems. Hypervelocity "darts" (Armour Piercing Discarding Sabot Fin Stabilized; APDSFS) fired from tank cannon are much harder to defeat, and using current or near term technology the only practical means of defeating such rounds is plates of high strength and density armour.
A tank cannon is a huge piece of equipment, firing large 120mm rounds and having massive recoil, so you need the tank to carry it around and use it effectively.
A man portable railgun would resemble a recoilless cannon:
The propellant charge would not be used to drive the round, but rather energize a MHD generator with the jet of high velocity gas exiting the venturi, while the long barrel will house the rails which actually drive the projectile. The actual projectile can be rather small and relatively light, since the damage is delivered in the form of kinetic energy. A small projectile moving fast enough could conceptually be able to engage helicopters and aircraft as well, although a very advanced sighting system and mount capable of rapid movement of the weapon will be needed.
The downside of this weapon will be much like regular recoilless cannon: the jet of the driving charge (in this case driving the MHD generator) will certainly alert any enemy of where you are, and you will need to leave immediately after firing.
Still, this would allow light infantry to be able to take on tanks on a more equal basis, as well as defeat most types of fortification (blasting through bunkers and buildings with relative ease), so something along these lines may be considered as the technology of railguns matures.
They both differ from conventional weapons in that they use electromagnetism to propel the projectile rather than using an explosive charge. Both of them need incredible amounts of energy, which is why they are not practical in an infantry weapon at the moment. The gun barrel and mechanisms do not need to be massively heavy, the problem is supplying the power.
The advantages of rail guns is that they are much simpler to build and operate than a coil gun. They are also more powerful as they have a direct contact between the projectile and the rails while the coil gun has a gap between them.
The advantage of a coil gun though is that the coils can be insulated from the outside world more easily, which could well make them more reliable in the long run. It will be harder for external conditions to interfere with the coils and the coils will take less wear and tear in use. Rail gun rails in particular are subject to a lot of wear even from normal use.
A coilgun is more efficient and needs less maintenance, there is no need for as high currents, and the rail itself won't get damaged as easily. Coil guns however typically need complex control mechanisms to turn the coils on and of, this makes them a lot more fragile and reduces their maximum launch speed. While a good coilgun needs less maintenance on a small scale, a large scale one might easily break so is not as reliable in big warfare. For infantry however a coilgun likely is more reliable due to the lower power usage, and them being able to not be affected as much by things like mud etc.
Not long ago I have been working on a new type of railgun which needs no complex control things like a normal railgun, and also can reach the high speeds, yet which reaches the efficiency of a coilgun, and so requires less maintenance to things like molten rails etc. However given current events it is better if I do not explain how it works, because someone might use it against people. I also don't know if discussing such things would even be legal in a place like this since it would be like handing over a blueprint to a high power high efficiency weapon.
But since this is a worldbuilding discussion place, you can still use them, it is possible even if you don't know exactly how it works. Also you might look to different more fun things like shooting liquid/molten metal. A friend an I once designed a lava shooting gun, such a thing is more a science fair project in practice since it has more of a cool factor than actual use (relatively expensive per shot, low range, and it just shoots very hot scary stuff but if you think about it, a single bullet likely is more dangerous). However in storybuilding such things can be rather cool. It is also something which was very easy to build in real life when you know what kind of methods to use. Extending the range is also doable using water to form explosions caused by the instant boiling but such a weapon realistically only really makes sense in a story where for example you have a super hero, or some evil person who likes to see people suffering and who for example uses it in huge bombs, or if there are specific creatures which heal very fast so that it keeps boiling them for a while. You could combine something like that with a coilgun or railgun and make it boiling metal. however it all depends on your story and how far it must be to what is used and known now, since if it needs to be stuff which is doable now, then a lava gun is just a science fair project which looks cool and keeps doing damage for a while after hitting.