Edit
An official version of this ship is available in the Command Division sourcebook.

Welcome to Starship Sunday, presenting a new spaceframe for the Star Trek Adventures roleplaying game, filling in some gaps until official material can be released.
This week is the New Orleans-class, in honour of the USS Thomas Paine (NCC-65530), captained by the Bolian, Rixx.

The Thomas Paine was described as a “frigate” in its first appearance and its class was not mentioned. The first true appearance of a New Orleans-class ship was as wreckage following the Battle of Wolf 359 during episode 4×01 The Best of Both Worlds, Part II. The destroyed ship was built from a store bought model kit of the Enterprise-D, modified to appear smaller than a Galaxy-class starship (one of several kit-bashed new starship classes seen in that episode).

Estimates on Memory Beta place the  New Orleans-class estimated to be 425 meters long, making it 2/3rds the size of a  Galaxy-class ship and 25% larger than an Intrepid-class starship like the U.S.S. Voyager. However, Ex Astris Scientia puts the size at closer to 340 meters, which is almost the exact same size as the Intrepid-class.

click the image for a PDF