Magnetic Accelerator Cannon



"That MAC gun can put a round clean through a Covenant capital ship."

- Sergeant Johnson, talking to the Master Chief on board the Orbital Defense Platform Cairo.

The Magnetic Accelerator Cannon, also known as Mass Accelerator Cannon, or the MAC gun or MAC cannon, is a large coilgun that serves as the primary offensive weapon for UNSC warships.

A larger variant is in service aboard Orbital Defense Platforms. Within the UNSC arsenal, only nuclear ordnance exceeds the power of the MAC. The M68 Gauss Cannon used by UNSC ground forces mounted on some Warthogs may be regarded as a relative of the MAC, albeit on a much smaller scale.

Mounting
The size of a Magnetic Accelerator Cannon is such that it is normally an integral component of a warship's structure. Some types of Defense Stations are literally built around the massive weapon for orbital defense. A good example of this is Cairo Station. The MAC gun can be clearly seen protruding from the rest of the platform.

Ammunition
A typical ship-based MAC fires slugs of either ferric tungsten or depleted uranium slugs at 30,000 m/s. The high muzzle speed gives the 600 ton slug the kinetic energy and momentum necessary to damage a target and partially mitigates the unguided nature of the slug and its lack of maneuverability. ODPs fire an 3000 tonne slug at 40% of the speed of light, enough to utterly destroy even the largest Covenant ship.


 * The Super MAC Slug can be seen on the level Cairo Station; Go out of the elevator to the bomb and immediately turn left, then go into the hollow rail in the middle of the room, you will see the 3000 ton slug being placed into the firing chamber. In other words, stare down the moving thing in the middle of the room. Consequently, walking into the firing chamber will result in the Master Chief being fired out of the MAC gun to his death.

Aiming
The integration of the MAC to its hull means the entire warship or station must maneuver to aim the weapon. Even with an AI aiming the gun, the required precision and the 'dumb' nature of the ordnance fired means that hitting an evading target at 100,000 kilometers is extremely unlikely.

Firing
The firing process of a super MAC gun can be seen in the level Cairo Station. The process uses electromagnetism to fire a ferric-tungsten slug at high velocity. A huge amount of current is put through the first solenoid (coil of conducting wire) which creates a strong magnetic field which attracts the metal slug. As the slug passes into the solenoid, the solenoid is quickly turned off and the second solenoid, which is further up, turns on, which attracts the now high velocity metal slug just like the first solenoid, and the process is carried on. By the time the slug is fired out the end of the barrel it has been accelerated to a speed 40% of the speed of light. At the same time a pair of thrusters on the bottom side of the station fire for a couple of seconds to counteract the acceleration imparted to the station. The process then repeats. It normally takes five seconds to recharge capacitors as well as load the slug, which is why boarding craft have to be deployed to take the stations out.

Standard Magnetic Accelerator Cannon
The standard ship-mounted MAC fires a 600-ton ferric-tungsten projectile with a depleted uranium core at 30,000 m/s (this is circa 2525 - MAC technology might have improved since). The large amount of energy needed to fire the weapon (the muzzle energy is 19.9 terajoules (E=.5mv^2), to be precise) is particularly onerous on a warship, and the extended recharge time is a significant factor in combat against Covenant warships as multiple MAC rounds are required to penetrate Covenant shields. The standard MAC is sufficient to destroy any human vessel or severely damage an unshielded Covenant vessel. Even so, standard MAC rounds seem useless against the Forerunner Dreadnought.

The has been seen using its MAC cannon as a kind of orbital bombardment, firing 6 rounds within 9 seconds at a Scarab from orbit as well as armies of enemy infantry. However judging by the fast rate of fire, and the fact that two direct hits were required to down the Scarab, the Spirit of Fire's cannon may either be a variant that sacrifices power for a fast fire rate, uses smaller slugs, is a special version for orbital bombardments or is an earlier, weaker version of MAC.

An experimental version of the MAC was developed to fire three successive rounds on a single capacitor charge. A prototype was mounted on the.



"Super" Magnetic Accelerator Cannon

 * Main article: Orbital Defense Platform

A UNSC Defense Platform typically mounts a much larger and more powerful version of the standard MAC, nicknamed "Super MAC" or "the Big Stick." These Platforms were the main defense of UNSC held planets and with the help of these platforms bought a little time to mount a better defense.

These cannons fire a 3000-ton ferric-tungsten round at 40% the speed of light, impacting with a massive amount of kinetic energy, almost 7.5 petajoules (E=.5mv^2). This is powerful enough to penetrate and destroy most fully shielded Covenant warships. By receiving power from ground-based power plants, orbital platforms could achieve recharge and reload times as short as five seconds. Due to prohibitively large power and sizing requirements, no UNSC ships are thought to be equipped with Super MAC guns.

M68 Gauss Cannon

 * Main article: M68 Gauss Cannon

The Gauss-cannon is a UNSC weapon mounted on the Gauss Warthog. It uses MAC technology, but on a much smaller scale. It is used as a light anti-armor weapon.

Other MAC Sizes
Although never explicitly elaborated upon, there may be many more different sizes of MAC based on the sizes of possible mounts. For example, one might extrapolate that a frigate would mount a smaller, less powerful cannon than a supercarrier or a, if only for power management issues. Conceivably, a 'large' ship could mount many 'small' MACs. However, the lack of such occurrences might suggest that the power of a MAC, once the mass and volume of all attendant components (ex. capacitors) are accounted for, does not scale linearly. There is one known exception (destroyers), which are outfitted with two MAC cannons. The Pillar of Autumn had one large MAC cannon which could fire three 600 ton rounds in succession on a single charge (see below).

MAC Location
Many believe that the MAC barrel is located near the underside of the ship, where there are three large plates. However, it is more likely that the barrel is located along the entire length of the ship. Logically, the multiple powerful magnets needed to accelerate a 600 ton slug to 0.1c requires an exceptionally long barrel, allowing for many magnets to affect the projectile. The huge 1.17 km length of the Pillar of Autumn would facilitate this, making the most likely muzzle location of the MAC barrel to be located at the protrusion at the ship's bow. This is also supported by the fact that if you look closely at the protrusion, you can see what looks like an opening.

Space Stations MAC Location
Further supporting the hyper cargo elevator, the player can look up and visibly observe the Super MAC platform in action. The slug travels through the entire length of the tower, and exits at the "top" of the further nozzle. Later in the level, the player can notice the loading zone of the slugs at the base of the firing chamber.

Appearances
The following unit types mounted some form of MAC weaponry.


 * s
 * s
 * s (wartime refit)
 * Orbital Defense Platforms
 * UNSC Destroyers
 * UNSC Frigates