Drives

Introduction

Astrogation drives are the primary method by which spacecraft traverse the galaxy. Despite the numerous methods in operation the most common will be represented here, in addition to notation of experimental or proprietary drive systems, or special research initiatives.

Proven Types

Chemical

Ion

ECRM

The electrodeless cyclotron resistojet motor utilizes resistance heating of a (typically non-volatile) liquid medium to assist in the expansion and ignition of a propellant accelerated by a cyclotron; usually sorium. These engines are poor main drives as their mass and volume is relative to their efficiency. The larger the ECRM, the greater the amount of propellant to be ignited and the more resistor chambers required. A very large ECRM can use many times more energy to run than other equivalent engine types.

HELFIRE

As a drive, the helical electrostatic Lorentz-force induction ram engine is among the most efficient methods of electronic propulsion. It is notable as the culmination of several drive systems hybridized. The HELFIRE system is adaptable and takes on many forms. It typically sees service as a main engine in smaller craft and as a maneuvering thruster in capital ships. A HELFIRE uses electrostatic induction to affect a chemical change in a propellant. Most examples use lithium ions for fuel.

Nuclear

ICF

Inertial confinement fusion, when discussed as a spacecraft propulsion system, is one of the more effective forms in common use. A 1,000 ton engine of this type can produce 100,000,000 Newtons of thrust quite easily. Fusion fuel pellets - typically hydrogen - are fed into a magnetic field where they are bombarded by lasers. The pellet, no more than a few millimeters in size, heats up and undergoes fusion nearly instantly. The release of energy is directed as exhaust using a magnetic field.

Photon

Plasma

Antimatter

SCAP

Solid Core Antimatter Propulsion is the simplest method of antimatter-based propulsion. The eponymous solid core of the engine is bombarded with microscopic amounts antiprotons, the energy released in their annihilation heats the core, which in turn heats the propellant (usually hydrogen). High thrust levels can be achieved with this method, but care must be taken not to melt the core and propellant efficiency is low, meaning large amounts of reaction mass are required.

GCAP

Gas Core Antimatter Propulsion is slightly more difficult than SCA, microscopic amounts of antimatter are injected into a large mass of propellant, usually hydrogen or water, which is heated to a plasma by the annihilation. Magnetic confinement is used to contain the pions produced in the annihaltion to further heat the plasma and direct it through the exhaust nozzle to create thrust. It uses less propellant than SCA, but produces more waste heat.

BCAP

Beam Core Antimatter Propulsion directly reacts equal amounts of matter and antimatter, and uses magnetic confinement to use the production from the annihilation reaction directly for thrust. This form of antimatter propulsion is hardest to engineer, and produces a low amount of thrust, but reduces the mass required for fuel and propellant to a fraction of a percent of that of other drives. BCAP drives do have problems with gamma rays and annihilation products transmuting parts of the engine into radioactive isotopes.

Experimental Types

Gravitic

Bias

The bias drive projects a gravity well in front of and behind the craft equipped with it. For such a vessel to be crewed it must also project a well above, below, and to either side of the craft to maintain inertial equilibrium on board. Bias drives consume fantastic amounts of energy and require antimatter/matter reactors to operate. By regulating the streams of particles to their collusion points, the gravity wells can be throttled, thus affecting velocity. The gravity wells make excellent armaments.

However, this drive is considered too dangerous for manned spaceflight; if even one well is out of sync the results are deadly.

Diametric

Utilizing little understood 'negative mass', this drive uses a diametric chamber to propel a spacecraft in the direction desired. The 'positive mass' is anchored to the ship while the negative mass is suspended in space and it's position is adjusted electromagnetically. Negative mass is pulled toward positive mass' gravity well as would be expected. However, negative mass has a 'negative gravity fountain', which pushes rather than pulls. The closer the negative mass repulsor is moved to the positive mass resistor, the faster the positive mass is pushed away from the negative gravity of the negative mass, and the faster the negative mass is pulled toward the positive mass. Once set, the distance between the masses never changes as they are equal.

Negative matter is a form of exotic matter whose mass is measured in a sign opposite of positive matter. The majority of it's properties are considered extreme. The synthesis of such matter is too expensive to make this drive practical.

Disjunction

A less volatile and more benign gravitic drive method, the disjunction drive takes advantage of 'cosmic strings'. Cosmic strings are intensely gravitational one-dimensional defects in the universe which form wherever non-symmetrical phase transitions have occurred (not unlike cracks). Minor strings are found radiating from most stars but major strings can be found extending between nebulae and regions of intense starforming. However, they are always broken by domain walls, their two-dimensional equivalents.

Laser interferometers are used to find these strings and, once located, a craft equipped with a disjunction drive navigates to the string under conventional propulsion. Sophisticated computers pinpoint the precise location along the string most ideal for disjunction. Initiating disjunction is as simple as occupying the proper point in spacetime. Ideally, the string is aligned with the longitudinal axis of the vessel, whereupon it disassociates the gravity well of the craft from the craft itself.

It is thought to function by pulling the combined well of the entire vessel, including crew, at faster than the speed of light. The craft ends up occupying a point in space on the slope of the gravity well and is pulled along at tremendous velocity.

Although effective and capable of near lightspeed velocities, this drive requires weeks of computation and setup time to engage. Furthermore, coming into contact with a domain wall will stop the ship in question instantaneously with violent consequences.

Drive Safety

The sale, ownership and operation of most types of FTL drives is closely regulated by both governments and corporations. Used incorrectly or inappropriately, certain drives have the potential for extreme levels of destruction. While this may simply mean the complete annihilation of the ship trying to use the drive, other inappropriate activations, especially within a planet's atmosphere, can result in much more dangerous situations.

While most FTL drives generally have advanced safeguards in place to prevent this, jury rigged drives have been used in some instances as makeshift warheads. Given the potential this holds for extremist groups, the level of regulation and control surrounding drives is a well monitored and hotly debated issue.