The basics of Impulse Engine design have underpinned the feasibility and speed of interplanetary travel in the Alpha and Beta quadrants for centuries. Although often overshadowed by the achievements of warp drive, impulse drive is no less important to the ease and convenience of space flight. What warp drive does to make interstellar flight practical and expedient, impulse drive does for everyday interplanetary travel.

Although the design specifics of impulse engines may vary from culture to culture, there are four primary components that remain essentially the same through all of them: fuel storage, reactors, the space-time driver coils (cochrane coils), and the exhaust assembly. Notwithstanding the fact that all of these components are critical to operation of an impulse drive unit, the space-time driver coils, or cochrane coils are what allows vessels to achieve speeds and accelerations that would have otherwise been fuel prohibitive by Newtonian thrust-based systems such as ion drives.

Space-time driver coils are essentially extremely low-level subspace field coils. When energized by an active plasma flow, they lower the effective mass of a starship enough to allow ionized gas from the exhaust ports to propel the vessel at much higher speeds and extreme accelerations than would be normally be possible. In theory, this property of impulse drives could be used to propel a ship as fast as .99c, but because it is a sublight drive, ships operating under impulse power are still subject to the rules of relativity, meaning issues with time dilation can become a serious factor. It is because of this that impulse travel is generally limited to .25c, the speed commonly called "full impulse."

Impulse engines require a comparatively minute "amount" of subspace to operate; several hundred orders of magnitude lower than the subspace required for the operation of warp drive. It is because of this rather meager requirement that often subspace devices or interference which would make warp travel impossible in a given area have no appreciable effect on the operation of impulse drive. The plasma used to energize the space-time driver coils can be derived from a variety of different reactions, including total-conversion matter-antimatter, fusion, and even fission. StarFleet uses deuterium fusion reactors in their impulse drives, and channels the resulting helium plasma through the driver coil assembly to create the mass-lightening effect. Once the plasma passes through the driver coils, it is ejected into space through vectored exhaust ports, leaving an ion trail in the ship's wake.

Since it's first demonstration to Imperials during the skirmish at Imatia, impulse drive became one of the great envies of the Galactic Empire against the Federation. Their desire for such technology soon entered them into a trade agreement with the Ferengi Alliance, who provided them with 22nd century models and information from which to develop their own impulse drive technology.