Railgun

(Copied straight from .XML 'backup' file, needs formatting and corrections. ZM User (talk) 20:15, 22 April 2024 (PDT))

(Moved from "Rail Gun" since common usage both on 'real' Earth today and in the Swarm Universe is one word 'railgun' instead of two separate words 'rail gun'. -ZM)

Railguns

   A Railgun is a device that uses electromagnetic force to launch high velocity projectiles, by means of a sliding armature that is accelerated along a pair of conductive rails.  It is typically constructed as a weapon, and the projectile normally does not contain explosives, instead relying on the projectile's high speed to inflict damage.  The railgun uses a pair of parallel conductors—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.  It is based on principles similar to those of the homopolar motor.

   Railgun construction is complicated by two conflicting requirements.  First, the two rails cannot be allowed to move from their mutual alignment.  Even minor misalignment will prevent a projectile from reaching the aim-point.  This issue is exacerbated by the inevitable wear on the rails from the short-circuit-level currents flowing between the rails and the projectile, and railguns typically require maintenance after several shots in order to maintain military-level accuracy.
   Second, the device depends upon controlled high currents, so the rails must be both electrically and magnetically isolated from their surrounding structure.  This is made more complicated by the need for an open window at the end of the rails for the projectile to leave the ship through as well as a military railgun's operational requirement for rapid reloading.

Projectiles

   A railgun projectile must also be structurally sturdy as the launch acceleration may cause insufficiently strong payloads to fracture.  Payload failure during 'launch' usually ends up damaging or even destroying the rails.  A railgun projectile typically does not contain any mechanical or electronic components due to the rapid acceleration and the magnetic flux from the launch current going THROUGH the projectile.  The projectile is usually a completely inert lump of metal made from a material selected for its magnetic permeance and resistance to erosion, then shaped solely for mechanical alignment with the rails.
   Because of these operational issues, a railgun is easier to build than a coilgun but it is harder to use repeatedly.
   During the Swarm war the PDRs generally used tungsten- or depleted uranium-doped steel slugs as the hardest and densest materials available that would work.  The larger railguns generally used Titanium-doped steel as the best mix of quality and availability.

Development

   People have been building railguns for research and entertainment ever since electricity was invented.  The first one was probably an accident, though.  A conductor accidentally dropped on a pair of bus-bars will be accelerated in the direction dictated by the magnetic fields generated by the short-circuit current.  Unfortunately, the current also eats both 'rails' as well as the projectile, so very few experiments can be run before all components must be replaced.
   Confederacy technology made railguns and coilguns practical, and both were developed concurrently.  The first one fielded as a practical weapon by the Confederacy Navy was a small railgun mounted on ships as a point-defense weapon where it could be fired at incoming projectiles and small craft.  The Point-Defense Railgun or "PDR" worked well, but it suffered from erosion of the rails and required maintenance after only a few shots.  However, as its use was often the only separation between "survival" and "complete destruction" of the mounting ship, the maintenance issues were quietly accepted as a necessary evil.
   Once the basic technology had been demonstrated, Central Command went for broke, building the largest railgun it could and a humongous ship to carry it into battle.  To minimize rail erosion, the railgun was extended as long as possible to enable a lower current but retain the desired muzzle velocity.  The "Hero" Class of battlecruisers were built around a pair of 150-meter-long spinal railguns and they were the largest direct combatant ship the Confederacy Navy built for the first decade of the war.  These weapons accelerated a 1000 kilogram -one metric tonne- projectile to 100 kilometers per second.  At this point in the war, we were aware of no possible defensive structure which could keep a "Hero" projectile out.  Anything hit by one was dead.
   As large as the Hero Class was, as tough as the ships were, and as accurate and powerful as their main weapons were, the Heros were considered to be a failure in service.  They were simply too big.  The railguns were a one-shot-one-kill weapon system, but the entire 200,000 ton hull had to be aimed at the target before the spinal railguns could fire at it.  Any structure able to be defined as a 'ship' was maneuverable enough to avoid this.  Once the Sa'arm realized the Hero's weakness, the larger Sa'arm ships simply avoided being in front of one and kept it busy while it got swarmed over by smaller ships.
   Within a few years it was obvious that the Hero class could not survive in combat without a screen of ships with no other purpose than its protection.  Further, no target worth shooting at could be aimed at for long enough to hit.  The surviving units were reluctantly withdrawn from offensive service.  While several more were completed, the vast majority of hulls already under construction were modified to become the basis for the "Presidential" class of small-craft carrier.  Ironically, if the Presidents had been available when the Heros were first sent out, their small craft would have protected the Heros and they would not have been so futile.
   It took another half-dozen years to get the next weapon system developed.  One of the colonies scaled the Hero gun down to only 1/3 the size and firing a slug 1/10 the mass, calling it a "Junior Hero" gun.  This was mounted variously as a spinal mount on smaller ships, on a vertically pivoting mount with adjustable elevation on larger ships, and finally a turreted version on heavy cruisers almost as large as the original Hero.  All three versions were successful as weapon systems, but only the turret version made it into common use as the other two required the ship to keep a bow-on orientation on the target.
   At the same time, the colony developed an even smaller version, one firing a slug only 50Kg or 1/20th the size of the Hero projectile, calling it a "Baby Hero" gun.  This, in turn, could be a spinal mount on destroyer-sized ships.  These ships had the maneuverability to keep a Sa'arm warship targeted, giving these ships a one-shot-one-kill weapon that could not be deflected by defensive fire and really worked.  The maintenance issues remained, though, and once coilguns were developed in the same sizes the railguns were removed from service.
   Only the PDRs, the original Point-Defense Railguns, were retained in service throughout the Swarm War.  The equivalent coilgun, the PDC or Point-Defense Coilgun, was better in every measurable way but the old PDR still worked and was trusted by the fleet.  Most ships had up to half of their PDRs replaced by PDCs, but very few warship captains were willing to part with their last PDRs.

Confederacy Usage

Several types are in use by the Confederacy:

• Hero railgun fires a 1000 Kg slug of Titanium alloy accurately at 100 Kps.
• Junior Hero railgun fires a 100 Kg slug at 100 Kps.
• Baby Hero railgun fires a 50 Kg slug at 100 Kps.
• Point-Defense Railgun (PDR) is an AI-targeted automatic "Close-in Weapons System".

Story Usage

A textual analysis of the story repository, current as of 9/2019 and performed on 2019-09-21 and using SS Lib ver 1.15.06 (9/19/2019) identified the following usage counts for Railgun:

• Living a CAP Based Present by Allan Joyal 75 instances.
• Ending This Mess by Zen Master 13 instances.
• Independent Command by Zen Master 10 instances.
• The First Command by Zen Master 8 instances.
• Conrad's Folly by Allan Joyal 6 instances.
• We Few, We Happy Few, We Band of Brothers by LughIldanach 3 instances.
• Crisis at Ishtar by Allan Joyal 2 instances.
• Fly By by akarge 2 instances.
• Some Assembly Required by Nuke Danger, 3rd Aye 2 instances.
• Family Letters by Allan Joyal 1 instances.

(Someday this will be a navigation template.  It will provide a bar across the bottom of each article with useful navigation links.  Until then, this is just a placeholder to get rid of all the red "broken link" indicators. -ZM User (talk) 10:00, 3 May 2024 (PDT))