Weapons

Weapons are instruments used to cause harm to a target. This article deals specifically with space and anti-space weaponry.

Kinetic Weaponry
Weapons using kinetic energy (the energy of motion) to deal damage. The greater the velocity of the object relative to the target, the more kinetic energy it will possess. Such weapons can be as simple as rocks dropped into the path of the enemy ship or as complex as a coilgun. As solid pieces of matter, they do not home and must be directed at the target accounting for motion and potential evasive action.

In space, the effectiveness of kinetic weaponry is increased due to the vacuum environment. Without air resistance or gravity, they will continue along the path which they were propelled along until they meet another object, giving them infinite potential range. However, targetting limitations, evasion, and other factors cause them to have an effective range far lower than this.

Kinetic energy can easily be calculated by the following equation (as long as the velocity does not exceed approximately 10% of the speed of light):

KE=0.5 x m x v<sup2 (KE=0.5*m*v^2)

Where:

KE = kinetic energy

m = mass in kilograms

v = velocity in metres per second.

It is evident that an increase in velocity does more to increase kinetic energy than in increase in mass, as the velocity term is squared. Make sure not to confuse kinetic energy with force.

Some good general rules of thumb are that an object at 3km/s delivers kinetic energy equal to its mass in TNT and that an object at 200km/s delivers kinetic energy per kilogram approximately equal to a low-yield nuke. However, projectiles at these velocities will tend to overpenetrate and not deliver all their damage to the target, so it is wise to design them so that they will deform on impact and deliver more energy.

The main methods of propelling a kinetic weapon are through a gun, a railgun, a coilgun, or using a built-in rocket.

Conventional guns use an explosive charge to launch the projectile down a barrel towards the enemy. Modern rifles have a firing pin which strikes a primer charge on the cartridge, causing it to ignite. This releases a jet of burning gas which ignites the propellant charge, which then detonates. Most modern guns do not need an oxygen atmosphere due to the presence of oxygen in the charge.

Railguns use a pair of parallel charged rails through which accelerate a conductive projectile. Factors affecting the acceleration include magnetic field strength, rail seperation, railgun length, and projectile mass. Top current railguns can launch a 2kg projectile close to 4km/s with 6m long rails, but this requires a current through the rails of an enormous 6.5 million amps. Railguns are also notoriously inefficient and produce large quantities of waste heat. Projecting the projectile also causes major wear to the rails, which gets worse as velocity increases. And, due to the conservation of momentum, the railgun will need major bracing to avoid being ripped out of its sockets when the gun fires. Sufficiently powerful railguns actually make a good means of propulsion, if very inefficient. A railgun placed of axis is also likely to cause the ship to begin spinning uncontrollably.

Coilguns use a series of electromagnetic coils to accelerate a ferromagnetic (think iron, steel, nickel) projectile down the barrel. They can reach higher maximum velocities than railguns, but require even more bracing as each magnet is trying to explode under the forces involved. Factors determining the rate of acceleration are similar to those for railguns.

Rocket-propelled projectiles have an inbuilt rocket that causes them to accelerate towards the enemy, like an explosive-less, non-homing missile. The gyrojet is an example. Advantages include not having to worry much about recoil, but disadvantages include ineffectiveness at close range (they're still accelerating) and cost.