“The USS Kelcie Mae has a single warp nacelle, an underslung deflector dish, and a pointed hull rather than a saucer section. It’s this unusual physical arrangement that makes the ship stand out, at least from a visual standpoint. In fact, it reminds us distinctly of the Olympic-class USS Pasteur as seen in the alternate future of All Good Things under the command of Captain Beverly Picard …”
ST doesn’t have carriers because fighters are uncommon and bombers are unheard of, for a variety of good reasons. There are a few exceptions, like Jem’hadar “fighters” (which are basically equivalent to a smaller Bird of Prey in terms of crew and armament, but actually seem to serve as troop transports?), runabouts, or the Delta Flyer. That size of ship is also roughly equivalent to the Jedi ships, both in terms of travel range and capacity for violence.
@MikeyMongol @snowyday Yeah, they even make a note of how unusual the Defiant is.
“Tough little ship!”
The Defiant is an interesting middle ground, basically a corvette type of thing, and it’s only practical because it has a cloak and it’s (for the ST universe) grotesquely overpowered and overgunned. Well it’s only practical because the writers wanted it to be, but that’s the in-universe explanation.