From Stargate Wiki
- "...it is nowhere near fast enough to achieve interstellar travel."
- — Jonas Quinn
A Sublight engine is an engine unit used to propel spaceships at subluminal speeds in both space and atmosphere.
Sublight engines are capable of accelerating ships to velocities that are capable of propelling them out of the atmosphere of planets and across solar systems in short amounts of time. Sublight engine speed has also shown to be dependent on the size of the engine units, smaller ships can reach speeds of 10,000 km per hour while larger ships have been known to reach 637,300,000 km per hour. Sublight engines have several functional speeds such as military and emergency thrust and often have auxiliary systems to ensure they are active in emergencies. Sublight engines are dependent on inertial dampeners to maintain the safety of the occupants. (SG1: "Prometheus", "Critical Mass", "The Siege, Part 3", "Aurora", "Beachhead", "Company of Thieves", ATL: "Suspicion")
The Ancients had very advanced sublight engines capable of propelling ships across a solar system in several hours and engines powerful enough to maneuver a city-ship. If sufficient power is supplied to their engines, they are capable of being modified to reach 0.999 the speed of light. (ATL: "The Defiant One", "First Strike", "The Return, Part 1")
The Asgard had powerful, highly maneuverable sublight engines capable of countering the extreme gravitational effects of a black hole and engaging in complex turns at top speed and evade enemy fire. (SG1: "New Order, Part 1", "Camelot")
Goa'uld Ha'taks use their sublight engines to decelerate after exiting hyperspace and rely on crystals for control. Death gliders have powerful engine units which operate in both atmosphere and space. (SG1: "Enemies", "Serpent's Song", "Exodus")
The Ori Motherships have powerful sublight engines to propel their enormous ships. Their smaller ships have engine units which operate in both space and atmosphere at fast velocities. (SG1: "Camelot", "Flesh and Blood", "Line in the Sand")
The Tau'ri have sublight engines reverse engineered from Goa'uld, Asgard and Ancient technology. These engines rely on control crystals to function and are capable of accelerating to 110,000 miles per second. (SG1: "Prometheus")
The Wraith have sublight engines capable of maneuvering their massive ships through space, the engines are powerful enough to move the ship but unable to move the ship if it were any bigger, unless and enormous surplus energy is available, otherwise they would be torn apart by their inertia. (ATL: "Letters from Pegasus", "Enemy at the Gate")