The Daedalus class is an interpretation of an early Matt Jeffries design for the Enterprise. It was first published in Stephen Whitfield's "The Making of Star Trek", on page 82.

Greg Jein made a model of the ship several years ago which appeared in the background of some shots in many episodes and thus the Daedalus became canon.

What I've done is tried to imagine how the Daedalus might have evolved after twenty or more years in service. It has been retrofitted with many experimental systems developed for the Constitution class starships. The warp nacelles have been updated, and you can see a large warp core chamber on the spine of the engineering hull. The sensor package has been upgraded to Constitution standards as well.

The ship I've modeled is the U.S.S Farragut, NCC-165. This is the ship James Kirk served on before being given the command of the Enterprise. When the Farragut was decommissioned, the name was reassigned to a new Constitution class starship, NCC-1702.