Magnetic Accelerator Cannon (TFCverse)

"Noise? How the hell do those things produce noise in space?" 
"They aren't audible outside the ship, but inside is a whole other story. It's like being inside the Galaxy's largest bell." 
- Two UNSCDF Navy Servicemen
The Magnetic Accelerator Cannon (MAC Gun) has been the primary spinal weapon of United Nations Space Command Defense Forces Navy warships since the 2450s. Providing a rock solid punch that not even Covenant ships could sustain for long. The weapon is known for range, accuracy, and sheer destructive power as its one of the most destructive weapons ever devised by human hands. While in the post-war era, the MAC Gun has been supplemented by the Energy Projector, it still retains significant viability on the modern battlefield due to its flexible nature, which means that it is going to remain a staple of UNSCDF Navy warships and UNSCDF Air Force orbital defense platforms for likely centuries to come. 
The MAC Gun replaced a variety of different weapon systems in service that the UNSCDF had at the time which could serve as spinal weapons. These weapons were an eccentric mixture of different types but they were primarily directed energy weapons: Free-Electron Pulse Lasers, Heavy Particle Beams, and Proton Particle Beams. This was due, in-part, to the development of Titanium-A Battleplate which was dense and strong Armor Metamaterial that provided superior radiation protection against Proton Beams as well as being much more difficult to penetrate with lasers and heavy particle beams, resulting in a dramatic shift in UNSC design to a primarily kinetic based weapon loadout with anti-ship missiles primarily mounting Casaba Howitzers -also known as Plasma Spears- simply because the durability of Titanium-A had rendered many of the previous weapons obsolete. 
It should be noted that there are a number of magnetic weapons within service in the UNSC across time that were used in a wide variety of roles. To make this article relatively concise, this article will be focusing on Magnetic Accelerator Cannons in reference to the spinal weapons commonly found on UNSC warships. 
== Principle ==
The basic principle of the Magnetic Accelerator Cannon is simple enough to understand. Its a coilgun, meaning it uses a sequence of magnetic coils applying electromagnetic force to pull-push the projectile along using a form of physics known as Gaussian Acceleration. When the electromagnetic coils engage, they first pull projectile down the barrel, but after it passes the halfway mark of the coil set, it starts pushing the projectile while the next coil set -if the weapon has it- begins to pull the projectile further down the barrel. Through this process the kinetic round gains momentum at an exponential rate, therefore gaining potential energy until the round flies from the muzzle and towards the target at velocities simply unattainable with propellant based weaponry. 
It should be noted however, that this primarily applies for Magnetic Accelerator Cannons prior to 2550, when the UNSC finally made Helical Railguns at the Magnetic Accelerator Cannon level plausible. This results in the weapon being able to take advantage of not only Gaussian Acceleration which is what coilguns use, but the superior Lorentz Acceleration -due to its higher force-to-energy conversion ratio- which is used by railguns, for getting around the friction issue that made railguns on the scale of the MAC gun burn out incredibly quickly, the UNSC had the Covenant to thank for that. By studying Covenant plasma applications, the UNSC learned how to make Plasma Conduction possible at the shipboard Magnetic Accelerator Cannon scale, ODPs had long used Plasma Conduction to throw their rounds at significantly higher velocities than what ships could manage. This circumvented the issue of friction entirely since the round doesn't touch the rails or the barrel itself, instead a layer of plasma completes the circuit allowing the magnetic coils and rails to provide acceleration. This has the added benefit of allowing for greatly increased muzzle velocities because friction isn't as much of an issue. Technically, these new guns were Plasma Augmented Helical Railguns, but they were still called MAC guns to save a mouthful. 
== Recoil Absorption ==
The recoil of a MAC gun when it is fired is absolutely immense. The weapon itself weighs hundreds if not thousands of metric tons, the projectile its firing at relativistic velocities weighs at minimum hundreds of tons. All of this force has to go somewhere, it doesn't magically vanish into the either. This recoil force is partially reduced by using non-Newtonian fluid shock absorbers and magnetic rails whose purpose is to deliver the recoil force to the superstructure over a longer period of time than what would happen otherwise, reducing stress delivered to the spaceframe since its not delivered all at once but over the period of the firing and post-firing call it maybe a half-second all told. Additionally the sheer mass of UNSC warships which is on the order of millions if not billions of metric tons of metals, polymers, and ceramics which further helps reduce the strain delivered to the superstructure. Finally, the last part that contributes to making sure that UNSC ships aren't rendered unspaceworthy after just a couple of firings is the sheer mass of the gun system itself whose mass is not inconsiderable. 
When firing the MAC, the recoil force despite all of this is to sufficient to cause the entire warship to ring like a bell when the weapon fires. In early MAC armed ships, this noise was sufficiently loud enough that eventually, outright hearing loss would manifest, requiring flash cloning of the ear in order to rectify the issue. This issue would get straightened out by the turn of the 26th Century. 
== Projectiles ==
Like all UNSC magnetic weapons; the projectiles for the MAC Gun is made of a tungsten metamaterial which has a density that's slightly higher than Depleted Uranium, roughly 22-grams per cubic centimeter, resulting in a higher sectional density allowing for extremely high level of material penetration. Furthermore the material provides excellent resistance to the high acceleration and heat associated with firing MAC guns. This allows the rounds to be relatively small, with an emphasis on relatively as the rounds are still absolutely enormous, with the 600-ton Heavy Rounds used by Cruisers, having dimensions of 2x8.69-meters. 
Part of the reason for using a singular material instead of varying materials is primarily because once you get up above a certain velocity, roughly 3,000-meters per second or 9,842.52-feet per second. The material of the round doesn't matter, because on impact the round will convert itself into plasma in a very violent release of energy through a hypervelocity impact. By manufacturing projectiles out of this singular material it saves a significant amount of credits since you don't need acquisition of multiple material types for the factories to convert into projectiles. 
Also, contrary to popular belief, MAC guns can't fire in void engagements projectiles with a conventional explosive payload or EMP warheads. The sheer velocity of the round and the forces involved at launch would either result in the round exploding in the barrel or the payload being obliterated on impact before it can function. However, it is possible for bombardment rounds as they're fired at significantly lower velocity, to carry a payload that's worth something. Usually highly specialized kinetic kill munitions that are launched to increase the damage done by low velocity rounds in a low velocity orbital bombardment. 
However, besides the unguided kinetic slugs and specialized bombardment rounds that MAC guns are most widely known for. Other things can be fired through the barrels of this immense weapon. Kinetic Kill Vehicles usually, however Harpoon Torpedoes, Cargo Pods, and even small space craft can be launched via the MAC; though the last one can only be launched by notably large MACs and those are usually of a specialized design mounted to special ships. 
Regardless, the ability to fire Kinetic Kill Vehicles provides the MAC an effective range that normally wouldn't be possible with a kinetic weapon due to the fact that these projectiles are guided and hit just as hard as conventional MAC rounds. During the Human-Covenant War however, a major improvement would be made to these Kinetic Kill Vehicles as a way to boost their velocity after launch which would be done by strapping the propulsion assembly from a couple of Archer Missiles to the round, giving the projectile an acceleration curve. 
== Effects ==
The effects of MAC cannon strike against an unshielded void target is frankly devastating. The rounds launched are literal boulders traveling at a velocity that's a few tenths of a percent of lightspeed. When they impact, they don't penetrate the target. Instead they smash into it with all of the subtly of an asteroid striking a planet, when it hits, one of two things happens depending on if the target has sufficient armor to cause the round to completely vaporize on impact or if it doesn't, 
* In the former case the target has a visible ripple go through it as the round vaporizes transferring its momentum and kinetic force into the target while sending a plasma jet into the target that has the same momentum as the round which just vaporized on impact. This can ignite the atmosphere inside the ship, causing the pressure hull to rupture and tear itself to pieces as a surge of fire rips through the target causing a dramatic increase in atmospheric pressure inside the pressure hull as the atmosphere violently expands due to the surging heat. In these cases, the ship usually has the mass and survive to take such a blow, but the area where the round impacted would be completely unrecognizable compared to everything else and you would have large amounts of shock damage. 
* The latter case is arguably a hundred times worse, because the round isn't fully vaporized on impact. Thus part of the projectile manages to penetrate the target, as it does so and goes ripping through bulkheads, decking, and overhead, the round transfers a little bit more of its kinetic energy to the target as it goes through it like a relativistic wrecking ball. Atmosphere ignites as each successive impact occurs, violently compressing the atmosphere with each breached compartment, hypervelocity spalling is sent flying when the round passes through a bulkhead which causes further damage, etc. Like the in the previous case, the target is rippling apart but it does so in an even more catastrophic fashion often disintegrating as if it had been a ball glass that had just been smashed by a wrecking ball, the vessel flying apart in all directions amid a catastrophic flash of light. 
Covenant vessels, while exceptionally durable by UNSC standards at the start of the Human-Covenant War couldn't survive a direct hit from a Magnetic Accelerator Cannon unless they were one of the big ones and even then, the vessel would suffer shock damage and have casualties on every single deck. That being said, their were Covenant ships that were sufficiently armored that the phrase "Non-penetration" comes to mind. The ships that could do this were primarily Covenant Heavy Capital Ships, though some of the lighter Covenant warships, most notably ORS class Heavy Cruisers when properly angled against incoming fire, could pull this off.
The effects of a "Non-Penetration" with a MAC gun isn't what it sounds like. The round impact and vaporizes into plasma, but due to either angling increasing the thickness of the belt relative to the round or through sheer thickness, the resulting plasma jet fails to punch through the target. Instead, the target rings like a bell as dozens if not hundreds of tons of material is blasted away from the target in a flash of light. This leaves behind a glowing gouge in the ship's exterior and spalling damage can be sent down into the hull. Spalling occurs when fragments of say armor break off the back of the armor and is driven into the superstructure. This can have fatal results for crew members if it manages to penetrate the pressure hull. 
Another thing that could happen with the effects of a MAC hit involve the energy shields. When a MAC round impacts an energy shield, the shields have several things they must absorb within the space of a fraction of second. First they must absorb the round impacting and vaporizing upon the barrier, then they must deflect the ensuing plasma jet, while absorbing the kinetic energy that's delivered to the shield emitters and generator. If the energy shields in a given sector aren't strong enough, depending on the strength of the shields several things could happen:
* The first is that the round destroys itself on the shields and they absorb the plasma jet but doing so completely collapses that sector. This is generally bad, but can be survivable if your Point-Defenses and CIWS are on the ball. 
* The Second is that the round shatters upon the shields, but the shields aren't strong enough to stop the resulting plasma jet. Depending on a ship's tonnage and the size of the round, this can result in the armor getting a fresh gouge or the plasma jet punching through the armor and ravaging the pressure hull beyond. 
* The third is arguably the worst case, the shield fails before the round is completely vaporized, then the armor is impacted and damaged if not outright penetrated by a plasma jet and then what's left of the round, a literal boulder impacts at a greatly reduced velocity and mass. This usually results in greatly localized damage, but even so, said damage would still be significant. 
=== Orbital Bombardment Effects ===
Depending on the velocity of the orbital bombardment. The effects of a MAC strike against a planet can have a wide variety of effects. In Low-Velocity Orbital Bombardment, essentially asteroid impact level velocities, a few dozen kilometers per second. A round's destructive effects can be described as essentially a localized earth-penetrating nuclear warhead without the fallout. Not the greatest for causing devastation over a wide area for which nuclear warheads are better for that as are lighter kinetic armaments at full power. These strikes can be used on strategic targets, but several times during the Insurrection they've been used as a means to force rebels to surrender.
In High-Velocity Orbital Bombardment, the effects are much more devastating. On par with large scale asteroid impacts in terms of devastation, everything in an entire region will be utterly decimated by either the impact itself, the resulting earthquakes, the shockwave, or the thermal pulse. A catastrophe that is both eerie to watch from orbit and at the same time utterly appalling because of the sheer devastation that's unleashed.
== Models, Projectiles, and Yields ==
MAC guns are arranged by Mark as for how they are classified, they are also classified by coil type. Which refers to the abilities of the gun and can also give a hint to the weight of its standard projectiles. It also gives a hint as to the weapon's recharge time and wherever or not its burst capable. The ship classes that the gun is usually mounted on as well as its nominal yield will be listed in the list below. One thing that must be noted is that for UNSC Magnetic Accelerator Cannons, muzzle velocities are standardized to make fleetwide salvoes easier to coordinate with the mass of rounds being what increases the damage. The only exception to this rule are the Mark Vs that are the crowning jewel of the extensive weapon suite of UNSC Orbital Defense Platforms as well as Dreadnoughts, Battlecruisers, and Supercarriers. 
Prior to the Human-Covenant War and during the first 12-years of the conflict, UNSC MAC guns could manage at full power 12,000-km/s this gave unguided slugs a maximum effective range (where they could reliably hit a target that was paying attention) of roughly 84,000-kilometers or about seven seconds out, assuming that their relative velocity was close to zero. However, when relative velocity of the firing ship was taken into account and it wasn't zero, it could be much farther. The exception to this was the Mark V which due to the insane power the ODPs, capable of throwing a round out at significantly higher velocities than ships because it couldn't rely on relative velocity to improve the range of the rounds due to being in GSO. This velocity applied for slugs and kinetic kill vehicles, due to barrel and coilset wear, Heavy Rounds were typically limited to 10,000-km/s. 
In 2537, the UNSC, thanks to advances in metamaterials and electromagnetic coils, made it possible for all shipboard MACs to have increased velocities. This increase wasn't much, from 12,000-km/s to 15,000-km/s; but this allowed a significant increase in range with unguided munitions at targets that are aware of the threat with a minimum of relative velocity from the launching ship, up to 105,000-kilometers in fact. This made Heavy Rounds more powerful as well, velocities of 12,000-km/s were now attainable for the weapon. 
In 2550, the UNSC cracked the code on Plasma Conduction for shipboard MACs, prior to this, only SMACs made use of it as did UNSC Point Defense Railguns, this was because for the former the ODPs and ships which used SMACs had enormous power generation capability which meant they could do it efficiently. For the latter, it was primarily because the barrel and rounds were short and light respectively which made it significantly easier to generate the plasma to complete the circuit. Thanks to breakthroughs in studying Covenant plasma applications, plasma conduction could be applied to shipboard MACs and velocities previously thought to be unattainable with such weapons and indeed all UNSC shipboard kinetic weapons were suddenly possible. The standard velocity for shipboard MACs became 24,000-km/s, for unguided kinetic slugs, this resulted in a range against targets that were aware, with minimal launching ship relative velocity taken into account, to be hit at ranges approaching 170,000-kilometers. It also meant that MAC guns could have their shell weight greatly increased without having to worry about damage to the barrels, however, due to the sheer number of projectiles for the older MACs produced however meant that the lower yield rounds would remain in service for the foreseeable future. 
The projectiles fired by Magnetic Accelerator Cannons can also broadly be summed up, at least in regards to void warfare, into four general categories: Standard, Heavy, Guided, and Heavy Guided. Standard and Heavy projectiles are unguided slugs, once they leave the barrel, they are nobody's friend. Guided and Heavy Guided projectiles take the standard and heavy projectiles and make them smart weapons. Equipped with a multi-spectrum imager capable of thermal, lidar, and radar imaging along with a connection to the battle network and a Reaction Control System attached, these rounds are a little heavier than standard, by about five tons and are slightly longer. However, they allow for shots that ordinarily would be impossible with conventional unguided projectiles. 
=== Magnetic Accelerator Cannon Mark I ===
Developed before the notion of magnetic coils would reveal the mass of a given projectile, the Mark I Magnetic Accelerator Cannon which formed the spinal armament on Victoria class Armored Cruisers and refitted Block III Hyperion class Heavy Cruisers was when it entered service in 2453, quite simply put the most powerful magnetically accelerated, non-nuclear weapon ever devised by human hands. This weapon had a considerably smaller barrel bore than later MAC guns, with a nominal barrel bore of only 647mm with the coilset bore increasing it considerably, adding an additional 15-meters to the diameter of the weapon. Furthermore unlike following MAC variants, the Mark I could only fire one projectile size and lacked the ability to fire more specialized rounds that later variants would have the ability to do so, this round was a 647x13900mm round made of tungsten metamaterials at a velocity of 7,000-kilometers per second resulting in a 585.8-megaton impact.
While the Mark I was powerful, by the 2470s, it was made obsolete by the introduction of the Mark II MAC Gun which was vastly more powerful and more compact along with being much more energy efficient, making it theoretically possible for ships with considerably less power generation capability like Frigates and Destroyers to actually ditch the older spinal weapons and mount the Magnetic Accelerator Cannon. 
==== Mark 2490/64.7cm HRG - "Mini-MAC" ====
Usually for a weapon cast aside as obsolete, particularly for UNSC Weapons that were retired before the Human-Covenant War broke out, they would fall into obscurity. However, in this case, the Mark I Magnetic Accelerator Cannon didn't fall into obscurity because it was given a new lease on life when the weapon was revived in the early 2480s as a weapon that could replace the Mark 2457/35cm HRG as a bow flank weapon to supplement the firepower of Spinal MACs, additionally the weapon was looked into as a weapon to give smaller warships a punch that was worth something. 
This initiative was successful and resulted in the Mark 2490/64.7cm Heavy Railgun also known as the Mini-MAC entered service. This weapon took advantage of advances in electromagnetic coils to make the weapon much smaller, it went from having a bore when one counted the barrel and coilset of 15.647-meters to a more workable 5.647-meters, a 66-percent reduction in size. Additionally, the round size was shrunk considerably down from its previous size to 647x7000mm with a mass of 50-tons, despite the reduction in mass, spinal models like those mounted on cruisers above Heavy Cruiser tonnage as well as Gorgon and Halberd class Destroyers along a select few refitted Mako class Light Corvettes, could throw this projectile at 12,000-km/s resulting in a net gain in destructive power, 861-megatons of TNT equal. But it wouldn't be until after the start of the Human-Covenant War that kinetic kill vehicles would be developed for this weapon. 
=== Magnetic Accelerator Cannon Mark II - Light Coil ===
=== Magnetic Accelerator Cannon Mark II - Light Coil, Compact Barrel ===
=== Magnetic Accelerator Cannon Mark II - Light Coil, Heavy Load ===
=== Magnetic Accelerator Cannon Mark II - Rapid Coil ===
=== Magnetic Accelerator Cannon Mark III - Heavy Coil ===
=== Magnetic Accelerator Cannon Mark III - Heavy Coil, Multipurpose Launcher ===
=== Magnetic Accelerator Cannon Mark III - Rapid Coil ===
=== Magnetic Accelerator Cannon Mark IV - Heavy Coil ===
The MAC Mark IV Heavy Coil is a specialized variant of the Mark II Light Coil that had sufficient differences between it and the Mark II to earn its unique designation. Its a unique model that was specially designed for the Paris class Heavy Frigate as a way to give the class more of a punch then the existing Berlin class Frigate, Charon class Assault Frigate, and Stalwart class Aerospace Defense Frigate. Part of this was because unlike these previous designs, Heavy Frigates were meant to tangle with multiple lighter opponents, fight equally sized opponents to a standstill, and if necessary have the ability to deliver a very nasty sucker punch against larger opponents. 
During the Human-Covenant War, this would be one of three Marks of Magnetic Accelerator Cannon that was continuously improved and not phased out by newer marks; the others would be the Mark V and Mark VI respectively. With later models and variants providing the spinal armament for later Daring class Destroyers and Strident class Heavy Frigates. 
When mounted to a Paris class Heavy Frigate, the Mark IV Magnetic Accelerator Cannon runs approximately 50% of the ship's length, 267.5-meters with the weapon having a nominal bore of 1.5-meters, however, if one where to include the coils in the bore diameter, this adds another five meters to the diameter of the Magnetic Accelerator Cannon.
The ability for this model of Magnetic Accelerator Cannon to provide the ability of giving the Paris class Heavy Frigate an ugly sucker punch that was greater than conventional frigates is seen in the mass of the slugs launched by the Paris class Heavy Frigate. Note, the round size also applies to Daring class Destroyers and Strident class Heavy Frigates. 
* The Standard projectile for the Mark IV Heavy Coil measures 1.5x4.12-meters and weighs in at 160-metric tons
** In 2525, this projectile would impact with 2.73-gigatons of TNT
** In 2537, this projectile would impact with 4.3-gigatons of TNT
** In 2550, this projectile would impact with 11.06-gigatons of TNT
* The Heavy projectile for the Mark IV Heavy Coil measures 1.5x15.45-meters and weighs in at 600-metric tons
** In 2525, this projectile would impact with 7.17-gigatons of TNT
** In 2537, this projectile would impact with 10.33-gigatons of TNT
** In 2550, this projectile would impact with 41.49-gigatons of TNT
* The Standard Kinetic Kill Vehicle for the Mark IV Heavy Coil was of broadly similar dimensions to the Standard projectile and weighed in at 165-tons
** In 2525, this projectile would impact with 2.84-gigatons of TNT
** In 2537, this projectile would impact with 4.44-gigatons of TNT
** In 2550, this projectile would impact with 11.41-gigatons of TNT
*The Heavy Kinetic Kill Vehicle for the Mark IV Heavy Coil was of broadly similar dimensions to the Heavy Round and weighed in 605-tons
**In 2525, this projectile would impact with 7.23-gigatons of TNT
**In 2530, this projectile would impact with 10.42-gigaatons of TNT
**In 2552, this projectile would impact with 41.84-gigatons of TNT
=== Magnetic Accelerator Cannon Mark IV - Heavy Coil, Compact Barrel, Ultralight Load ===
=== Magnetic Accelerator Cannon Mark V - Station Coil or Super MAC ===
=== Magnetic Accelerator Cannon Mark V - Ultra-Heavy Coil ===
=== Magnetic Accelerator Cannon Mark VI - Super-Heavy Coil ===
=== Magnetic Accelerator Cannon Mark VII - Light Coil ===
=== Magnetic Accelerator Cannon Mark VII - Rapid Coil ===
=== Magnetic Accelerator Cannon Mark VIII - Heavy Coil ===
=== Magnetic Accelerator Cannon Mark VIII - Rapid Coil ===
=== Magnetic Accelerator Cannon Mark IX - Super-Heavy Coil ===
=== Magnetic Accelerator Cannon Mark IX - Super-Heavy Burst Coil ===
=== Magnetic Accelerator Cannon Mark X - Light Coil ===
=== Magnetic Accelerator Cannon Mark X - Rapid Coil ===
=== Magnetic Accelerator Cannon Mark XI - Heavy Coil ===
=== Magnetic Accelerator Cannon Mark XI - Rapid Coil ===
Category:UNSC Weapons
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