Magnetic Accelerator Cannon
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- Nils Thune: "Space? Those things even make noise in zero-gee?"
- Ponder: "If you’re inside a MAC ship when the cannon fires? I don’t know if you’re a religious man, Governor. But it’s a little like a church bell—"
- — Governor Thune and Captain Ponder discussing MACs.[1]
The magnetic accelerator cannon,[2] also referred to as a mass accelerator cannon[1] or MAC, is a type of heavy weapon system employed by humanity, primarily the spacecraft of the United Nations Space Command. Within the UNSC, MACs are defined as a heavy weapon that fires multi-ton projectiles at extraordinarily high velocities from the bow of a capital ship, orbital defense platform or mounted driver emplacement. They are hard-hitting, but relatively short-ranged.[3][4][5] MACs are coilguns employing Asynchronous Linear Induction Motor (ALIM) technology[3] and are typically used in military applications, though similar technology can be used in civilian mass drivers for industrial use.
Overview[edit]
MACs are fitted as a standard armament on most UNSC Navy vessels, ranging from small Gladius-class corvettes to Marathon-class heavy cruisers and even carriers or refit civilian ships such as the Phoenix-class colony ship. With a handful of exceptions, MACs are typically spinally-mounted, meaning that the entire ship is built around the gun, with the cannon running a significant portion of the ship's length. However, the technology is not exclusively used in spinally-mounted MACs, with naval coilguns (themselves sometimes referred to as "Mini-MACs")[2] and even ground-based weapons such as the M68 Gauss cannon and M99 Stanchion operating on the same principle.[1]
Operation[edit]
MACs operate on the basis of a coilgun. When firing, a series of stacked coil motors are sequentially activated, propelling a projectile with vast amounts of kinetic energy.[2] The construction of the weapon takes the form of a series of coiled conducting wires (or solenoids). When a solenoid is activated, the projectile is attracted to the coil. As the projectile reaches the coil, a second coil is activated, attracting the projectile further down the barrel of the gun. This process is repeated as the projectile travels the length of the gun, with each successive solenoid accelerating the projectile to higher and higher velocities. As such, the longer a MAC's length is, the faster the muzzle velocity of the fired projectile.
This process differs from that of a railgun - a similar weapon system that feeds electrical current through a projectile to accelerate it along two conducting rails. Nonetheless, railgun weapon systems are occasionally referred to as MACs - as in the case of the Mini-MAC armament of the M510 Mammoth.[6][7]
To fire a MAC, UNSC ships must draw power from the fusion reactor into a series of capacitors, storing the generated energy for firing. As such, charging the MAC draws power away from other sub-systems such as engines. As such, a MAC can be pre-charged and fired when ready, though at the cost of power to the aforementioned systems. Without the charge being maintained, the charge level does deteriorate. However, MACs can be fired at lower charge levels than 100%[8] though likely to lesser maximum velocity. Likewise, firing the weapon at lower charge rates would also allow the weapon to fire more often if needed.
Ammunition[edit]
MACs are capable of firing a wide array of munitions, depending on bore and model. Some MAC rounds are extremely dense and constructed of ferric tungsten,[3] noted by Captain Wallace of the frigate UNSC Commonwealth as a "heavy round".[9] In the case of the MACs fitted onto the refit-colony ship UNSC Spirit of Fire, the rounds fired from its MACs are "low-mass"[10] or consist of three-hundred-ton depleted uranium slugs.[11] The MAC of the Spirit of Fire was later modified in a special project conducted by Ellen Anders, resulting in a specialised MAC capable of firing rounds that emit an EMP upon impact.[12] Other munitions that can be fired from MACs include semi-autonomous drone missiles[13] and for the larger 27 metre guns of UNSC Infinity, even include cargo pods and small spacecraft.[14] A special kind of MAC round fired by the refit-UNSC Pillar of Autumn was composed of a ferrous core and an outer layer of tungsten carbide, which allows the round to splinter on impact with an enemy vessel, similar to the shredder rounds fired by an assault rifle.[15]
Due to this variation, the masses, velocities and sizes of MAC projectiles can vary, ranging from 10 metre-long, 160 ton models fired by frigates and cruisers,[1] to 600 ton[3] depleted uranium models fired by Paris-class heavy frigates[16] up to 3,000 ton[3] super-heavy rounds[17] accelerated to 4% of the speed of light[18][Note 1] by the Erőd-class orbital weapon platforms above Reach.[19] The MACs of UNSC Infinity are additionally capable of firing various "sub-caliber" munitions (For example, three-thousand-ton slugs) for its massive twenty-seven metre bore, alongside some of the special types mentioned prior.[20] A type of 1,200 feet (366 meters) long MACs have a range of 10,000 miles (16,093 kilometers).[21]
A slug fired by Cairo Station's massive "Super-MAC" gun.
A cross-section of t
