The Chimera-class was a type of starship in service with Starfleet during the latter half of the 24th century. (Star Trek Encyclopedia) The Chimera was designed as a fast frigate and launched in 2366. It is derived from the Excelsior-class sharing the same saucer and nacelle design. The Chimera has three nacelles, one located above and two below. (Ship Recognition Manual, Volume 1: The Ships of Starfleet)