The Reliant-class was a type of cruiser starship in service to the Federation Starfleet in the 23rd century. The Reliant-class was an enhanced and refitted design of the Anton-class cruisers, in a similar fashion as the Enterprise-class was a refit of the Constitution-class design. (FASA RPG module: Federation Starship Recognition Manual)
The Reliant series of ships is a part of what is known, overall, as the Miranda-class of starships. The designation Miranda extends to older versions of these same vessel before these refits took place, as well as the Reliant refits and other subclasses with different configurations of outboard pods. The terminology referring to the smaller number of vessels of the Reliant series is specific to those vessels that were converted from the Anton class and a number of vessels built in the 2270s and 2280s.
As the engineers began dismantling the Reliant for her refit, Starfleet decided to install FWF-1 and FIE-2 engine systems aboard instead of the standard FWC-2 and FIC-3 systems which were normally incorporated on Mk IV Anton-class ships. Because of the new warp and impulse engine installations, the Reliant now had a radically changed exterior appearance which led Starfleet to christen the design as a new starship class.
As well as the engine changes, the Reliant was also equipped with a "roll bar" weapon pod which gave the ship a better firing arc and allowed for photon torpedoes to be added to the ship's arsenal. The "roll bar" also contained phaser banks which were mounted on the edges.
The Reliant was eventually re-launched on reference stardate 2/1507 as the class ship of the Reliant-class. Construction of new Reliant-class vessels took place at the Morena, Sol IV, and Salazaar shipyards at the rate of 10 ships per year. In all, 52 Mk I Reliant-class cruisers entered service. (FASA RPG module: Federation Ship Recognition Manual)
On reference stardate 2/1802 the Mk II Reliant-class cruisers entered service. The Mk II's were enhanced with an improved impulse drive system and the installation of FH-11 phaser banks. In all, 46 Mk II Reliant's entered service.
The Mk III Reliant-class entered service on reference stardate 2/2204, and was equipped with a more powerful set of warp engines, which actually decreased the ship's mass to 161,600 metric tons. In all, 175 Mk III Reliant's entered service. (FASA RPG module: Federation Ship Recognition Manual)