An impulse engine (a colloquialization of internally metered pulse drive) was a nuclear fusion-based propulsion system used primarily for sub-light travel.
History and specifics
- The Last Unicorn RPG module: Starfleet Academy Handbook implies that the first impulse designs were created in 2169, but the phrasing leaves it open to interpretation as to whether they were a new design put into use. Canon sources place the discovery of the impulse engine in the 21st century.
In the early-to-mid 23rd century, Starfleet would test new impulse engine designs at their Impulse Engine Testing Grounds located in the city of El Paso, Texas. (TOS - Who's Who in Star Trek comic: "Issue 1")
Following the discovery of the Bajoran wormhole in 2369, any starship crew that required access to the wormhole had to drydock their vessel at Deep Space 9 to have impulse energy buffers mounted around their impulse engines. (DS9 novel: Bloodletter)
Each impulse engine consisted of one or more nuclear fusion reactors, a series of subspace field coils, and a vectored thrust nozzle to direct the plasma exhaust. The engine produced a high energy plasma that was vented out of the thrust nozzles to propel the starship. In the event of an emergency while at warp, the impulse engines could also be utilized to temporarily generate a Warp field to maintain warp speed for the vessel or the primary hull in the event of Saucer separation. (ST reference: USS Enterprise Owners' Workshop Manual)
The deuterium-based fusion reaction of the impulse drive also served as a secondary power system for a starship, and was utilized for powering internal systems. (TNG reference: Star Trek: The Next Generation Technical Manual)
In addition to a standard impulse drive, several subgroups of impulse engine existed. A hyperimpulse engine, such as the drive system utilized by the Timeship Aeon, had exceptional speed, but high power requirements. (ST video game: Star Trek Online; VOY episode: "Future's End")
Impulse engine types
Earth and Federation impulse drive types
- FIB-3 type
- Loknar-class class VII/VIII/IX frigate (Mk I/Mk II/Mk III)
- Thufir-class class VIII/IX destroyer (Mk I/Mk III)
- ST reference: USS Enterprise Owners' Workshop Manual
- TNG reference: Star Trek: The Next Generation Technical Manual
- ST video game: Star Trek Online
- VOY episode: "Future's End"
- TNG episode: "Relics"
- TOS novel: The Rings of Time
- TOS novel: Final Frontier
- ENT novelization: Broken Bow
- Last Unicorn RPG module: Starfleet Academy Handbook
- DS9 novel: Bloodletter
- EV - Cloak and Dagger comic: "Part 2 of 2"