Linear warp drive

Linear warp drive is a variation on warp drive used in Federation starships, recognizable through the flattened, vertically oriented nacelles.

One of the first production vessels using this technology was the USS Prospero (NCC-1820), launched around 2265. 

The first ship-of-the-line with this drive was the USS Dekatur, the 2270 prototype of what became the in the late 2270s. (, vol. 1 [revised])

The USS Enterprise (NCC-1701) was upgraded to linear warp drive in its refit around 2273. 

starships using this drive were active from the late 23rd and 24th centuries. (DS9: )