The Thunderbolt Fighter is the Imperial Navy's primary heavy atmospheric fighter. Its nose armament will make a mess of anything in front of it, and its airframe is easily loaded with whatever payload a particular mission requires, like missiles (air-to-air and air-to-ground) or bombs, or even reconnaissance equipment. Though it looks about as aerodynamic and maneuverable as a flying brick (seriously, its wings are like slabs of metal), it apparently is capable of serving as an air superiority fighter, and its bulk brings survivability and ease of repair -- its pilot is actually capable of repairing damaged drive systems mid-flight!
It is equipped with a rocket in its tail in addition to its two jet engines; the rocket is not suitable for space combat, but rather used to launch from an orbiting mother-ship into the upper atmosphere (and vice versa), as well as take-offs from hydraulic "fast-launch" ramps (essentially aircraft-carrier catapults, but on the ground).
The model was produced by Forge World, with rules first published in Imperial Armour Volume One - Imperial Guard and Imperial Navy, and periodically updated since (most recently in Imperial Armour Aeronautica).