(covers information from an alternate timeline)
In an alternate timeline, the Yellowstone-class runabout was an upgraded design of the Danube-class runabout designed in the late-24th century. The Yellowstone-class was equipped with tetryon plasma warp nacelles and designed for a variety of mission profiles.
The prototype vessel of this class was the USS Yellowstone, which was designed by the Starfleet Engineering Corps and constructed in 2371. Two key members of the design team were Lieutenant Lasca and Ensign Harry Kim. Kim was responsible for designing the new tetryon plasma warp engines.
The Yellowstone had one key design flaw in terms of working out a dilithium fracture problem. Several weeks were spent on resolving the problem, which was "cured" with new plasma flow equations. On stardate 49011, after six months of work, Lasca and Kim conducted a presentation to Admiral Strickler on the Yellowstone, focusing on the fracture problem. Strickler found the design of the Yellowstone to be interesting.
Although spaceworthy, construction on the Yellowstone was still underway in early 2372. Many of the ship's defensive systems were yet unfinished, including unplaced safety interlocks. The runabout was stored in spacedock. (VOY: "Non Sequitur")
Ships of the classEdit
The Yellowstone-class runabout only appeared in the alternate timeline shown in "Non Sequitur" and is the only appearance of a runabout in Star Trek: Voyager. It is unknown if the ship design existed in the "prime" reality.
While not explicitly stated, the name Yellowstone implies that, unlike the Danube-class runabouts, which are named after rivers, Yellowstone-class runabouts would named after national parks.
In the video game Star Trek Online the Yellowstone-class is a special version of the Danube-class runabout. It has a more smoothly sloped hull than the Danube-class and features a unique tetryon plasma impulse engine which can vent plasma into space behind it, damaging and even immobilizing ships that pass through it.