(covers information from several alternate timelines)
List of unnamed Earth starship classes.
Delta-shaped hull class []
This type of starship was used by Starfleet during the mid-22nd century. The primary hull was triangular in shape, and had two nacelles mounted port and starboard angled upward from and slightly above the hull.
These vessels were equipped with forward and aft phase cannons. (ENT: "The Expanse", "Twilight")
This class was also present in the mirror universe. (ENT: "In a Mirror, Darkly", "In a Mirror, Darkly, Part II")
In an alternate 2165 this type of vessel was included in the Earth convoy destined to settle on Ceti Alpha V. (ENT: "Twilight")
The CGI model of the Delta-shaped hull-class ship was designed by John Eaves and actually started out originally as the "back end" of the Emmette-type warp ship model seen flying above Luna during the opening credits of the Star Trek: Enterprise, and was constructed as such at at Foundation Imaging.
During the second season, Eaves was called upon to modify his original design. The final draft script of "The Expanse" called for "warp two ships". Visual Effects (VFX) Supervisor Robert Bonchune clarified, "The next season when we needed some "older" starships (than NX-01), John Eaves went ahead and truly finalized the complete shape as was seen in the episodes. However, since this was considered a more advanced production version, the "back end" old style rocket exhausts were deleted and replaced with more "advanced" 'nurnies' and 'greebling'." [1] Bonchune described the inspiration of this design as "a kind of Romulan/Federation hybrid." [2]
Detached primary and secondary hull-class []
This type of starship was used by Starfleet during the mid-22nd century.
These vessels had a primary and secondary hull connected via the nacelles, which were directly attached to the primary hull and via pylons to the secondary hull. (ENT: "Storm Front, Part II")