View source for TechMemo:Sublight Drive

{{header menu}}{{techmemo}}{{BuTECH}}
Star Fleet Engineering<br>
Technical Memorandum<br>
Stardate: 100116 (16 January 1998)
Updated:  170403 (3 April 2005)

RE: Sublight Drive Systems
----
There are a number of slower-than-light, or sublight, drive systems employed by the various races of the Milky Way Galaxy.  By far the most common system employed by the races that the United Federation of Planets has yet encountered is the ion drive system.  The following is a list of various drive types and general classifications.

==REACTION DRIVE SYSTEMS==

Reaction drives are those drives that expel mass to create momentum through the law for conservation of momentum of a center of mass.  These drives utilize solid propellant rockets, liquid propellant rockets, fusion-powered rockets, etc.  The latter are o ften employed in a class of drive system known as ion drives.

===Ion Drive Systems===
;(including Impulse Drives)
An ion drive system creates forward momentum by expelling a high-velocity stream of electrically charged particles through a nozzle.  Some advanced ion drives implement thrust vectoring or reversing technologies to allow the vessel equipped with such a dr ive to have greater maneuverability and the ability to reverse acceleration without reversing the heading of the ship.  More primitive systems generally require the vessel to point the drive nozzle in the direction in which the ship needs to accelerate.

Ion drive systems are almost always supplemented by maneuvering thrusters which may themselves be small ion drives.  Maneuvering thrusters change the three-dimensional heading of the ship.  Normally, these thrusters apply force transverse to the direction of desired motion without effectively altering the primary component of momentum, but rather rotate the ship.  All maneuvering thrusters must have an opposing set of thrusters in order to function properly.  Since a maneuvering thruster has the ability to push in only one direction, there must be a thruster which imparts motion opposite to the direction of any given thruster so that the vessel can stop its turn.

The most advanced impulse drives in use in the Federation actually use inertia reduction technology.  Since 2344 and the introduction of the ''Ambassador'' class, compact space-time drive coils, similar to those used in warp drives, were included in the impulse drives.

===Photon Drive Systems===
One special type of reaction drive is the photon drive which uses photons, (which are light), to propel the craft.  Depending on the technology employed, photon drives may exhaust nothing detectable, harmless colored light, or ravening beams of heat, lase r light, gamma-rays with extreme intensities.  Due to the extremely small mass of the photon, this form of reaction drive, while nearly 100 percent energy efficient, is limited to accelerations of only a few gravity's.  These drives are ideal for craft wi thout inertial compensators because of their power efficiency.  However, performance limitations generally mean that they are not employed when inertial compensator technology would allow for greater accelerations without damage to the crew.

==GRAVITIC DRIVE SYSTEMS==

Gravitic drive systems include many of the faster-than-light drive systems, such as warp drives and hyperspace drives (including dimensional warp systems).  This technology may also be applied to sublight propulsion.

===Inertia Reduction Drive Systems===
;(including distortion kinetic drives)
Inertia reduction drive systems work by bending (or rather unbending space) so that the gravity well created by the ship is shallower than it should be for a ship of a given mass.  Thus, the effective mass of the vessel is reduced as is the impulse needed to give the vessel a given momentum; consequently, velocity can be increased.  These drives will not propel the ship without being coupled with another form of sublight propulsion.

===Gravity Planing Drives===
A gravity planing drive warps the gravity well of the ship so that the ship is pulled in any direction by the distorted gravity well.  This form of drive allows a vessel to accelerate at the same rate in any direction with equal facility.  Such drives are often paired with inertia reduction drives resulting in vessels with unsurpassed maneuverability.