Sci-fi roleplaying and worldbuilding community

User Tools

Site Tools


"Taihō" Scalable Mass Driver

The Taihō (Yamataigo: 大砲 “Cannon”) Scalable Mass Driver is a coaxial, Helical railgun, a sort of hybrid between a railgun and a coilgun. It can launch either magnetic slugs with dense tungsten penetrators, or, like a plasma railgun, toruses of plasma or balls of lightning that explode on impact and have devastating effects on electronics.

About the "Taihō" Scalable Mass Driver

Yugumo Corporation began a policy of reducing, with the goal of eliminating entirely, reliance on external vendors for their internal use. While Yugumo Corporation made a variety of plasma and antimatter weapons, for a kinetic solution, they had relied on Origin Industries systems such as the Light Gauss Starship Cannon.

When Cecily Winters was hired as Yugumo Corporation Vice President of Armaments Systems Development and Procurement in YE 43, she was presented with this problem as the most pressing issue for her division. With the requirement the system be scalable at any tier like the Plasma Projection System, the Scalable Mass Driver, soon dubbed the “Taihō” (meaning simply “cannon” in Yamataigo) was her solution. Disregarding specifics of implementation, the Scalable Mass Driver was designed as a core weapons platform to build specific applications from, rather than a single weapons system application.

Nomenclature Information


The exact appearance of the “Taihō” Scalable Mass Driver depends on the particular application and any platform that carries it. For handheld or crew-served applications, the weapon looks much like the underlying platform on which it is built, such as a pistol, rifle, or machine-gun. Mounted Mecha and Starship applications depend greatly on the turret and vehicle configuration. All applications feature in common the shroud to protect and cool the helical rail system. In general, any hand-held application at any tier will have Yugumo's design aesthetic that skirts the line between sleek and blocky.

"Taihō" Personal Defense Weapon
Taihō Personal Defense Weapon

Discharge Information

Discharge is dependent on firing mode.

Kinetic Projectiles

  • Muzzle Flash: A small flash from the electrical arc between the rails.
  • Retort: In an atmosphere, a roar and hiss as the projectile's velocity heats the atmospheric fluid to plasma, and a crack and whine as it breaks the atmospheric sound barrier.
  • Projectile/Beam Appearance: In an atmosphere, there is a glowing trail left by the projectile where it superheats the surrounding atmosphere to plasma, similar to that of a tracer round. Outside of an atmosphere there is nothing besides the projectile itself.
  • Effective Range: Dependent on tier.
  • Rate of Fire: Rate of Fire is dependent on implementation, and generally is inversely proportional to the size of the weapon. Power-armor-sized mass drivers are capable of rapid fire like a GPMG with proper power, larger ones fire more slowly.
  • Recoil: Appropriate to the size and rate of fire of the implementation. Perceived recoil is reduced by the force acting outwards on the rails, perpendicular to the firing plane in all directions.
  • Velocity: Dependent on application.


  • Muzzle Flash: A small sphere of blue-white light as the plasma torus or ball lightning is launched.
  • Retort: In an atmosphere, a roaring, hissing sound as the plasma torus or electricity superheats the atmospheric fluid.
  • Projectile/Beam Appearance: A torus of plasma or sphere of ball lightning that is launched at such a velocity to appear to be a blue-white beam to most observers.
  • Effective Range: Up to 300,000 km (186,411 miles). Max. range is 900,000km (559,234 miles).
  • Rate of Fire (Cannon)1): A single discarge every three seconds.
  • Rate of Fire (Gun)2): Two discharges per second.
  • Recoil: Negligible relative to size of implementation, but scales up and can be significant for an oversized weapon for the platform.
  • Velocity: Near-light speed

Ammunition/Energy Source

Handheld personnel-tier weaponry is powered by the BR-E2A battery magazine, while power-armor and frame tier weaponry is powered by the PA or Frame. Mounted and emplaced weaponry at any tier is powered externally by the platform. Crew-served weapons systems may be powered by a battery or an external power source. Battery-powered applications may recharge wireless when in the presence of a power field such as aboard ship or in a building. Battery-powered applications intended for the Star Army of Yamatai may instead use the BR-28 Series Battery Magazine or YB-28A Triple-Power Magazine.

Plasma and ball lightning mode is fed by the platform's onboard plasma system, if any, and as such may fire as long as the plasma system has access to matter. Without a plasma system or other source of plasma, the application may only fire kinetic projectiles. Details on kinetic projectiles are below.

  • Ammunition: Ferrous-alloy magnetic slugs with tungsten penetrators
  • Purpose: Variable-tier, depends on application and platform.
  • Round Capacity: Limited by size of application and platform
Kinetic Projectile Damage Quickchart
Damage Tier Kinetic Projectile Size
1 3x15mm
2 5x25mm
3 7x35mm
4 10x50mm
5 12x60mm
6 15x75mm
7 20x100mm
8 30x150mm
9 50x250mm
10 125x625mm
11 180x900mm
12 250x1250mm
13 500x2500mm
14 1000x5000mm
15 2000x10000mm

A ferromagnetic shell around a shaped tungsten penetrator allows for the penetrating mass to be launched by electromagnetic force at very high velocities. Smaller weapons can achieve supersonic-to-hypersonic3) velocities, while starship-tier weapons achieve relativistic velocities of significant fractions of the speed of light.

Kinetic penetrators contain a sensor module and small reservoirs of nano-machines and compressed gas in order to disintegrate the round and disperse it widely if it is launched and travels more than 900,000km without striking anything.

Weapon Mechanisms

  • Firing Mechanism: Electronic firing
  • Loading: Dependent on application and platform. Handheld weapons use various-sized detachable mags, crew-served and mounted weapons use an external ammunition feed. All models have a port for an external plasma supply.
  • Mode Selector: Dependent on application and platform.
  • Firing Modes: Dependent on application and platform. Plasma firing modes require access to plasma.
  • Safety Mechanism: Dependent on application and platform.
  • Weapon Sight: Dependent on application and platform.
  • Attachment Hard Points: Dependent on application and platform.


The “Taihō” Scalable Mass Driver is just a core system, and much of a particular weapon system implementation depends on external parts and accessories to complete it. When mounted and connected, it can also serve as an emitter for an onboard Plasma Projection System.

"Taihō" Armor Service Rifle
Taihō Armor Service Rifle


  • “Taihō” Scalable Mass Driver
    • Pistols, Rifles, Submachine-guns, Support Weapons: 1250 KS per tier
    • Mounted and Crew-Served Weapons: 1000 KS per (tier x 1.5)
    • Automatic Fire (Burst, Full-Auto) Capability: additional 10% of base cost (additive).
    • Atmospheric Hypersonic Capability: additional 10% to base cost (additive)
    • Relativistic Base Speed: additional 10% to base cost (additive)
    • Capital (Tiers 13-15): final total of above increased by 10%

Example applications are described below. Firing Modes, Effective Atmospheric Range, and velocity are for kinetic projectiles. Relativistic velocities are in vacuum only, these weapons are Hypersonic in an atmosphere4). Velocity is one category greater in a vacuum. Effective range in vacuum is approximately one Light-second (≈300,000km) for all Relativistic velocity weapons, and about 1/1000th of a light-second for Hypersonic weapons, and much lower for slower weapons. Kinetic projectiles self-destruct, disintegrating and dispersing after 900,000km in any case.

:!: Attention :!:
Buyers5) must ensure they read the Catalog6) carefully to ensure they select the appropriate form factor, firing modes, rate of fire, and range for their intended use case.
All sales are final. Yugumo Corporation and its subsidiaries do not offer refunds for reasons not covered by manufacturer's or extended warranty.
Scalable Mass Driver Price Quickchart
Tier Nomenclature Description Price Form Factor7)8) Modes/RoF9) Eff. Range10) Velocity11)12)
1 Yu-W6-1A Light Pistol 1250 KS P:P SF,SA 200m B
2 Yu-W6-2A Service Pistol 2500 KS P:P SF,SA 240m T
2 Yu-W6-2B Personal Defense Weapon 2750 KS P:B SF,SA,BF3,FA360 300m T
2 Yu-W6-2C Scout Rifle 2500 KS P:R SF,SA 500m S
3 Yu-W6-3A Service Rifle 4400 KS P:R SF,SA,BF3,FA240 600m S
3 Yu-W6-3B Light Support Weapon 4400 KS P:S SF,FA600 600m S
3 Yu-W6-3C Interdiction Rifle 4000 KS P:R SF,SA 2400m S
4 Yu-W6-W4304A Light Armor Service Rifle 5500 KS PA:R SF,SA,BF3,FA240 1600m S
4 Yu-W6-W4304B Light Machine Gun 6600 KS P:C,PA:S,M SF,FA420 1800m S
4 Yu-W6-W4304C Armor Service Pistol 5500 KS PA:P SF,SA,BF3 800m S
5 Yu-W6-W4305A Armor Service Rifle 6875 KS PA:R SF,SA,BF3,FA180 2200m S
5 Yu-W6-W4305B General Purpose Machine Gun 8250 KS P:C,PA:S,M SF,FA360 2400m S
6 Yu-W6-W4308A Heavy Armor Service Rifle 8250 KS PA:R SF,SA,BF3,FA240 4800m S
6 Yu-W6-W4306B Armor Interdiction Rifle 7500 KS PA:R SF,SA 7500m S
6 Yu-W6-W4306C Medium Machine Gun 9900 KS P:C,PA:S:M SF,FA300 5500m S
7 Yu-W6-W4307A Light Frame Service Rifle 9625 KS F:R SF,SA,BF3,FA120 7500m S
7 Yu-W6-W4307B Heavy Machine Gun 11550 KS P:C,PA:C,F:S,M SF,FA240 10,000m S
7 Yu-W6-W4307C Frame Service Pistol 9625 KS F:P SF,SA,BF3 3500m S
8 Yu-W6-W4308A Frame Service Rifle 12000 KS F:R SF,SA,BF3,FA90 18,500m13) H
8 Yu-W6-W4308B Frame Support Weapon 12000 KS F:S SF, FA180 24,000m14) H
8 Yu-W6-W4308C Light Auto-cannon 14400 KS M SA,FA180 48,000m15) H
9 Yu-W6-W4309A Frame Interdiction Rifle 15785 KS F:R SF,SA 75,000m16) H
9 Yu-W6-W4309B Auto-cannon 16200 KS M SA,FA120 100,000m17) H
10 Yu-W6-W4310 Light Starship Cannon 19500 KS M SA,FA90 100,000m18) R
11 Yu-W6-W4311 Starship Cannon 21450 KS M SA,FA90 100,000m19) R
12 Yu-W6-W4312 Heavy Starship Cannon 23400 KS M SA,FA75 100,000m20) R
13 Yu-W6-W4313 Capital Artillery 23595 KS M SS 100,000m21) R
14 Yu-W6-W4314 Heavy Capital Artillery 25410 KS M SS 100,000m22) R
15 Yu-W6-W4315 Super-Heavy Capital Artillery 27725 KS M SS 100,000m23) R

Form Factors

Yugumo Corporation uses very specific terminology in their technical and marketing materials to refer to specific weapon applications.

  • Pistol: Handheld weapon with a short barrel and no stock.
    • Light Pistol: A lightweight, small-caliber pistol often with a very short barrel. Highly concealable, generally a backup or undercover weapon.
    • Service Pistol: A pistol designed as a main sidearm for a security, law enforcement, or military force.
  • Submachine Gun: Pistol-caliber weapon with a high rate of fire and carbine barrel.
    • Personal Defense Weapon: A high-capacity, lightweight submachine gun meant to engage defensively at close ranges.
  • Rifle: Full sized weapon with a long barrel and stock.
    • Interdiction Rifle: An intermediate-to-large caliber rifle with a very long barrel and a very high muzzle velocity, intended for making precise shots at extreme ranges.
    • Scout Rifle: A lightweight rifle designed primarily to not impair the mobility of an individual. Generally not intended for military-on-military engagements.
    • Service Rifle: A rifle designed as a main arm for a security, law enforcement, or military force.
  • Support Weapon: Large, rifle-caliber weapon with a very high rate of fire. Bulky and somewhat hard to maneuver with. Generally full-auto only. Fires from a bipod or from the hip.
    • Light Support Weapon: A lighter, more compact, less powerful support weapon that can be fired from the shoulder like a rifle as well as from a bipod.
  • Crew-Served Weapon: Fired from a tripod or quick-release, manually-operated vehicle mount. Too large and powerful to be carried and operated on the move by an individual. Generally relies on external supplies of power and ammunition.
  • Mounted: A weapons system built into a vehicle, ship, or edifice, often turreted. Exclusively relies on external supplies of power and ammunition.
    • Autocannon: A light cannon, heavier than a heavy machine gun, capable of high-rates of fully automatic fire.
Taihō Service Rifle, Extended Taihō Service Rifle, Retracted
Extended Retracted
Taihō Service Rifle

Replaceable Parts and Components

An “XX” in the nomenclature represents the size of the weapons, such as Yu-W6-W4311 for a Light Anti-Starship helical rail/coil system. A “YY” in the nomenclature represents the size of the weapon plus 15, such as Yu-W6-G4326 representing the power control unit for the same system. Likewise, a ZZ represents that number with 30 added, so the plasma feed for that same weapon would be Yu-W6-G4341.

  • Yu-W6-W43XX Helical rail/coil system: 500 KS / tier
  • Yu-W6-G43XX Hyper Capacitor: 250 KS / tier
  • Yu-W6-G43YY Power Control Unit: 100 KS / tier
  • Yu-W6-E43XX Ballistic Computer: 300 KS / tier
  • Yu-W6-E4300 Multispectrum Sensor and Camera Suite: 400 KS
  • Yu-W6-E4316 Multicolor Light and Laser Package: 50 KS24)
  • Yu-W6-E4317 Wireless and Induction Communication Module: 75 KS25)
  • Yu-W6-P43ZZ Plasma Feed System: 100 KS / tier
  • Yu-W6-M43XX Kinetic Projectile Loading System: 125 KS / tier

Spare kinetic projectile magazines (Yu-W6-W43XXMG) for Yu-W6 handheld weapons are 5 KS / tier for every 10 rounds of capacity. Two magazines come with the appropriate applications, in 20-round capacity for pistols, 30-round capacity for rifles, 50-round magazines for submachine-guns, and 100-round ones for support weapons that accept detachable magazines. For example, a 100-round magazine for a Tier 3 (Heavy Anti-Personnel) Service Rifle would retail for 150 KS, while one for a Tier 8 (Medium Anti-Mecha) Frame Service Rifle would be 400 KS.

Handheld personnel weaponry made by Yugumo Corporation uses parts from the Yugumo E2 Energy Pistol and Sakura Type 43 Compact Carbine “Bushi”, depending on application.

Although personnel-tier handheld weapons systems have an external port to be connected to a plasma supply and the system to feed it into the firing chamber, but in practice these applications are used almost exclusively for launching kinetic projectiles. Power armor, frame, and ship applications are generally paired with a platform that has a a compatible plasma supply system, such as those manufactured by Yugumo Fleetworks.

Optional Attachments

Personnel-tier, handheld weaponry made by Yugumo Corporation uses accessories and attachments for the Yugumo E2 Energy Pistol and Sakura Type 43 Compact Carbine “Bushi”, depending on application.


Kinetic Projectile Price Quickchart
Tier Type Price (100 Round Box)
1 3x15mm 20 KS
2 5x25mm 30 KS
3 7x35mm 50 KS
4 10x50mm 100 KS
5 12x60mm 200 KS
6 15x75mm 300 KS
7 20x100mm 1000 KS
8 30x150mm 2000 KS
9 50x250mm 3000 KS
10 125x625mm 5000 KS
11 180x900mm 7500 KS
12 250x1250mm 10000 KS
13 500x2500mm 50000 KS
14 1000x5000mm 100000 KS
15 2000x10000mm 200000 KS

Yugumo Weapons Policies

The Yugumo Corporation does not allow the purchase of weapons from buyers outside of the Yamatai Star Empire. Starship models sold outside of the nation come without weapons and are discounted appropriately.

OOC Notes

The toroidal plasma firing mode is inspired by MARAUDER, an actual military plasma railgun weapon system developed in the early 1990's.

Yuuki created this article on 2021/12/19 19:03 using the Weapon Template. Approval Thread

Products & Items Database
Product Categoriesweapons: other
Product Name"Taihō" Scalable Mass Driver
ManufacturerYugumo Corporation, Yugumo Fleetworks
Year ReleasedYE 43
DR v3 maxTier 15
Tier 6 or greater, no less than 1 tier smaller than platform
Less than Tier 6 or smaller than platform
at 1 Yamatai (Planet) atmosphere
P:X: Personnel, PA:X: Power Armor, F:X: Frame, M:X Mounted
X:P: Pistol, X:B: Submachine gun, X:R: Rifle, X:C: Crew-Served Weapon, X:S: Support Weapon
SF: Safe, SS: Single Shot, SA: Semi-Automatic, BFX: Burst Fire (X rounds), FAX: Fully-Automatic (X rounds per minute, sustained)
B: Subsonic (less than Mach 0.8), TS: Transonic (Mach between 0.8 and 1.2) S: Supersonic (Mach 1.2 to 5), H: Hypersonic (Mach 5 or greater), R: Relativistic (greater than 0.2c, Hypersonic in atmosphere)
Sonic speed reference in 1 Yamatai Atmosphere
100,000m trans-atmospheric
180,000m trans-atmospheric
200,000m trans-atmospheric
250,000m trans-atmospheric
17) , 18) , 19) , 20) , 21) , 22) , 23)
300,000m trans-atmospheric
24) , 25)
generally only hand-held applications

corp/yugumo_corporation/weapons/taihou.txt · Last modified: 2023/03/19 12:08 by yuuki