A point defense cannon (PDC) is a rapid-fire projectile weapon used by all military-grade spaceships for defense against small ships and missiles.
PDCs are turreted rotary autocannons, utilizing a set of six spinning barrels to spew out thousands of rounds per minute to intercept incoming ordinance. PDCs are laid out on a ship's hull to cover all angles with overlapping fields of fire, providing a "curtain of steel" to more easily and effectively take out missiles. They also utilize thrusters on their rear to counteract the recoil of the firing cannon, that would otherwise knock the ship off course.
PDCs are computer-controlled, as even juiced-up human gunners would find it nearly impossible to effectively track and destroy fast targets like torpedoes. Human gunners do, however, select targets for the guns. The cannon turrets can also be retracted into the hull and can extend outwards in mere seconds.
PDCs are mainly used against guided ordinance, but they also perform fairly well as close range ship-to-ship weapons and can be used for direct space-to-surface strikes on personnel. The rounds seem able to penetrate the armor on most smaller ships.
Ships equipped with PDCs: Edit
- Donnager-class battleship: 59✕ Nariman Dynamics 40mm PDCs.
- Scirocco-class assault cruiser: 12✕ Nariman Dynamics 40mm PDCs.
- Raptor-class fast-attack-cruiser: Multiple turrets.
- Morrigan-class patrol destroyer: 2✕ Nariman Dynamics 40mm PDCs.
- Frigate-class frigate: Multiple turrets.
- Corvette-class light frigate: 6✕ Nariman Dynamics 40mm PDCs.
- Xerxes-class battleship: Multiple turrets.
- Truman-class dreadnought: 42✕ Redfield Ballistics 40mm PDCs.
- Leonidas-class battleship: 25✕ Mikazuki Munitions PDCs.
- Munroe-class destroyer: Multiple turrets.
- Phantom-class corvette: Multiple turrets.
- Amun-Ra-class stealth frigate: 4✕ Bush shipyards hypercooled PDCs.
- Magnetar-class battle cruiser: Multiple long-range PDCs.
- Proteus-class battle cruiser: Multiple PDCs.
- Pulsar-class destroyer: Multiple PDCs.
- Protector-class destroyer: Multiple PDCs.
PDCs were first seen in use on the MCRN Donnager, which used her numerous PDCs to shoot down a hail of plasma torpedoes launched by an attacking squadron of stealth ships. While most of the torpedoes were shot down, the advanced guidance systems of the torpedoes, as well as their sheer numbers, allowed two to get through and damage the Donnager's reactor. In the ensuing CQB battle, the Donnager used focused fire from her PDCs to destroy at least two assailants. As the Tachi (later to be renamed Rocinante) escaped the Donnager's hangar bay under a hail of small arms fire, it returned fire with its PDCs to wipe out many of the soldiers that had boarded the Donnager and blow open the hangar door, allowing the ship to escape.
During the Massacre of Anderson Station, Fred Johnson ordered the UNN Nathan Hale to open fire on the station with its PDCs, depressurizing the station and killing everyone onboard.
At the assault on Thoth Station, the Rocinante's PDCs were used to intercept torpedoes, destroy an anti-asteroid cannon on the station, and even take out the far better-equipped stealth ship by riddling it with thousands of rounds at point blank range. The enemy also used their PDCs to disable one of the Rocinante's port-side thrusters, hampering her maneuverability during the battle until Amos repaired the damage.
During the sudden and unexpected Ganymede Incident, due to the close proximity and chaos of the incident, PDCs were used as the main weapon between MCRN and UNN ships engaging in combat in Ganymede's orbit, destroying ships on both sides as well as several orbital structures, resulting in a cloud of debris falling to Ganymede's surface and the loss of thousands of military personnel.
When the Nauvoo was recovered, Johnson had it renamed the OPAS Behemoth. In addition to attaching several missile pods and railgun turrets, an incredible 170 PDCs were mounted to the ship's 2km hulk, giving it impenetrable defensive coverage to compensate for the ship's enormous target profile. This, however, did not compensate for the large.
Known Models Edit
Mikazuki Munitions PDC Edit
A type of PDC manufactured by Mikazuki Munitions that is used by some older UNN warships. The Leonidas-class battleship is equipped with a staggering 25 Mikazuki Munitions PDCs spread across the surface of its hull for maximum defensive coverage to compensate for their reduced accuracy as a result of the warship's low quality targeting suites.
Nariman Dynamics 40mm PDC Edit
A type of PDC manufactured by Nariman Dynamics that is used by most MCRN warships. The Morrigan-class patrol destroyer is equipped with two retractable Nariman Dynamics 40mm PDCs on its dorsal hull. Twelve of these guns are employed on the Scirocco-class assault cruiser and 59 are mounted to the Donnager-class battleship.
Redfield Ballistics 40mm PDC Edit
A type of PDC manufactured by Redfield Ballistics that is used by some UNN warships. The Truman-class dreadnought is equipped with 42 Redfield Ballistics 40mm PDCs spread across the surface of its hull for maximum defensive coverage with 4 mounted on either side of the bow, 28 on the neck, and 6 at the ends of the engines.
Kess-Hashari PDC Edit
A type of PDC manufactured by Kess-Hashari. The Outer Planets Alliance's retrofitted dreadnought OPAS Behemoth is equipped with a total of 170 of these weapons to compensate for its large target profile and poor maneuverability.
Bush Shipyards Hypercooled PDC Edit
PDC turrets specifically designed by the Bush Naval shipyards for Protogen's Amun-Ra-class stealth frigates. Retractable into the hull, they were designed to be rapidly cooled to work with the ship's stealth tech.
- PDC rounds are repeatedly described as "Teflon-coated tungsten". While not explained in detail in the books, this fact could make PDC rounds "armor-piercing sub-calibre ammunition;" a long narrow tungsten arrow acting as an armor breaking component, surrounded with light teflon-edged sabot, providing maximum barrel exit velocity.
- The teflon does not affect the ballistics of the round used, but rather allows for harder armor-piercing materials like tungsten to be used without excess barrel wear, as the teflon lubricates the bullet, allowing it to better engage the barrel without grinding it down. This would be a valuable trait to be found in autocannon ammunition, as with the very high rate of fire, harder AP ammunition would wear down the barrels quickly.
- In the book, unguided weapons like the PDC and railgun, are described as being viable only with ranges of less than 1000km. Given that PDC rounds are far slower than rail gun slugs, their effective range thus is presumably much shorter than even that. Based on the length of ships like the Donnager compared to the visual range at which PDCs are used, this effective range seems to be between 1-5 km.
- ↑ Spacedock Donnager-class video: https://www.youtube.com/watch?v=fFoLbsA5Sx0&index=7&list=FLM-MzPct64OCoqhDMwYb-QQ&t=293s
- ↑ The Expanse TV series: Season 1, episode 4 - CQB, 18:40