Grand Admiral, First Order Central Command
Image Source: Concept Art for Elite Dangerous, presumably copyright Frontier Developments, but got it from this page.
Intent: To make a gnarly hypervelocity cannon because proprietary weapons are in vogue right now.
Development Thread: N/A?
Manufacturer: The First Order
Model: 240mm/83 Mark 74 Hypervelocity Cannon aka “Hepastus Assault Gun”
Affiliation: The First Order
Modularity: N/A
Production: Minor
Material: Duraplast, Durasteel, Alusteel for the wepaon itself. Quadanium Steel for the turret mount.
Classification: Hypervelocity Cannon
Size: Ship-mounted and then some. There are necessarily miles of cables and other supporting gear woven into the ship.
Length: 20m
Weight: A lot. If the Iowa's 16/50's are anything to go off, several hundred tonnes.
Ammunition Type: 24cm Depleted-Baradium solid slugs.
Ammunition Capacity: Lots. Tens of thousands of rounds, probably.
Effective Range: Equivalent to 'Heavy, Long Range' Turbolasers.
Rate of Fire: 120 rounds per minute via gast gun principles (typically 10, 20, and capping at 36 round bursts, firing for 5, 10 or 18 seconds, respectively).
Special Features:
High Rate of Fire
Incredible Power (standard for HVC's)
Somewhat improved accuracy over standard HVC's
The weapon itself is a 4-barreled HVC, that overcomes the usual problems with firing rates on turreted shipboard HVC's by using the four barrels in sequence (a la gast gun principles, also not dissimilar to how gatling guns work) to reduce heat, stress, and metal fatigue as well as ensure accuracy of fire.
The power of the weapon is derived from the extremely dense shell striking at extremely high velocities. It is a weapon of brute force, pummeling its way through shields and pulverizing armor by virtue of the high kinetic impact and sheer volume of fire. As per standard HVC's, the weapon cannot sustain fire indefinitely (and given the nature of it, this is even more true). However the gast system reduces individual barrel stress, so it can fire for 18 seconds straight (though standard procedure is to keep it to 10 seconds bursts). after which there is a 8-10 second cooling/cycle time.
The turret itself is not the whole weapon system, rather it must be integrated into the vessel entirely, with webbed networks of coils to accelerate the shells and the ammunition loading bays located in the depths of the ship. This has a tendency to make the weapon system somewhat susceptible to damage, as it doesn't take a lot to throw off an acceleration coil. In regular operations, this means that the weapon requires a lot of maintenance and experienced technicians to ensure it operates properly. In battle, this means that the effectiveness can degrade rapidly as the vessel sustains damage.
Accuracy is very high (as to be expected from a high-velocity projectile weapon) with a very small spread thanks to the gast system. However the tracking rate of the turret itself limits it's ability to sustain fire on a smaller targets. Strike Craft in general are simply not targeted (the equivalent of trying to shoot a speedboat with the Iowa's 16 inch guns) though the volume of fire put out by the weapon may score a few accidental kills. Similarly, corvettes and frigates (assuming not of the big fat and slow variety) can relatively easily outmaneuver the weapon.
Range is technically unlimited, but realistically beyond conventional long-range (that is, that of a HLR Turbolaser) the target has so much time to make an evasive maneuver that it would only be effective on someone caught totally by surprise or against stationary targets.
Weaknesses:
Extremely large weapon emplacement. Ship must be at least 1000m long (and you could maybe fit one on that).
Particle shields must be lowered to fire.
Internally fragile.
Maintenance intensive and requires technical experts to function properly.
Limited ability to track smaller vessels.
For reference, here's what 120 rounds a minute looks like.
Isard-II for turreted HVC's
Figure it roughly equivalent to 60 turbolasers.
