Spaceships

(The content of this page is based on Terra Invicta Dev Diary #14: Ship design.)

A spaceship is a vehicle used to travel around and between celestial bodies. A spaceship is made of multiple types of components.

Hull
The main thing the hull determines is the number of nose and hull weapon hard points, the number of utility modules, and the length of the hull.

Power Plant
The power plant generates electricity for your spaceship. Certain drives require certain types of power plants. Power plants will scale in output and mass depending on the power requirements of the drive, up to a maximum output limit. They also have a power value that determines their mass per unit of output, and an efficiency rating that determines how much heat they output to the radiators.

Drive
The drive propels the spaceship. The main stats for the drive are thrust and exhaust velocity. Thrust combined with mass determines the ship's acceleration. Exhaust velocity determines how efficiently the drive uses each unit of propellant.

Propellant
Propellant comes in 100-ton tanks, and have no hard limit to the number that can be placed on a ship. However, each tank of propellant adds mass to the ship, which reduces its acceleration and gives diminishing returns for delta-V. The resources used to make propellant is determined by the drive.

Radiator
The radiator expels waste heat from the power plant. More advanced radiators can expel more heat per unit of mass. Radiator mass scales up to match the waste heat of the power plant. Radiators can be more or less vulnerable depending on the type.

Batteries
The battery stores power for weapons and other systems.

Armor
Armor protects your ships from damage. There are three armor slots: Nose, tail, and central hull. More advanced armor material will require less mass per unit of armor, with some materials having extra resistance to certain damage types. Armoring the hull will add much more mass than armoring the nose and tail.

Hardpoints
Nose hardpoints fire in a limited arc, but are generally more powerful than hull hardpoints. Hull hardpoints come in pairs placed on opposite sides of the ship, and can fire in all directions around the ship. Weapons come in the following types:

- Guns: Good old-fashioned cannon (chemical slugthrowers) with performance characteristics similar to modern naval weaponry. Low-tech, cheap, and don't drain your battery.

- Missiles and Torpedoes: Will chase the target. Constrained by ammo limitations. Nuclear weapons are among the warhead types. The difference between missile and torpedo in this context is mass; missiles go fast faster and have larger magazines while torpedoes carry heavier warheads. Also doesn't drain your battery.

- Magnetic weapons: Covers railguns and coilguns that launch high-speed projectiles that can be dodged or shot down. Can be used in orbital bombardment.

- Lasers: Never miss. Damage falls off over distance. Higher input power, larger optics and higher frequencies lead to more damage. Can be used in orbital bombardment, with some limitations for high-frequency weapons trying to bombard through an atmosphere.

- Particle weapons: Short-range weapons that can do severe damage to a ship’s internal components if it penetrates a ship’s armor. Also effective point defense weapons.

- Plasma cannon: These are essentially high-speed, low-mass projectile weapons; their design is based on what descriptions are available of the real-world Shiva Star and Marauder projects. In practice, we’re modeling them as long-range, low rate-of-fire weapons to give them a distinct role in combat. Deep in the tech tree.

Utility Modules
Utility modules contain everything else the ship might need, such as heat sinks, additional batteries, space marines, a science lab, systems that improve drive or weapon performance, space station and outpost kits, and ISRU modules

Ship Roles
Ships also have roles, which informs the game on whether the ship is a combatant or noncombatant, what range it should engage in during combat, and what its strategic range is (so how much delta-V it can carry). The role affects the autodesigner behavior and where the ship is placed in a combat formation.