There have been several variations of the Hover Unit, though they maintain the same overall appearance. Their primary design is of a bulbous egg-shaped hovercraft with two hatches on both sides near the rear of the craft (some models also featuring an alternate roof hatch and loading ramp on the underside). There are two seats for a pilot and co-pilot at the front of the craft, and the cabin can be modified to suit the needs of the mission being performed at the time.
The Hover Unit generally features a two-tone dark grey/black paint scheme, though in "Sonic Racer" several Hover Units had varying colors participating in a race Robotnik was holding as a trap to catch Sonic. Robotnik also had a personal hovercraft which featured a red and black color scheme.
Features and abilities
The Hover Unit is used as an attack craft; its typical armament consisting of one or more laser cannons mounted on the exterior of the craft. Robotnik's personal hovercraft was further armed with a missile launcher and cloaking device, which allowed him to escape undetected when his plans backfired.
The Hover Units were equipped with various sensors for use in patrolling Robotropolis, such as searchlights and Infra-Red sensors for detecting heat signatures of organic intruders (though these could be confused by emissions from power stations within the city). The Hover Units are also shown being capable of flying in space and surviving planetary re-entry, as seen when Sonic and Rotor commandeer one to escape an exploding space station in "Harmonic Sonic".
The Hover Units serve as the primary means of transport for Dr. Robotnik's military forces and his resources, piloted by his Swat-Bot army. On rare occasions, the Knothole Freedom Fighters were able to commandeer these craft and employ them against Robotnik, either to counteract one of his latest plans or as a covert means of infiltrating his operations.
Hover Tanks are low-altitude, uncovered Hover Units with a large mounted blaster.
Swat-Bot/Hover Unit model
A similar vehicle, but yellow/peach in coloration instead. This unnamed model is a non-flying Swat-Bot/Hover Unit hybrid that is used for repairs and maintenance throughout Robotropolis. It employs a series of hovering platforms that allow it to reach its destination almost as fast as the Hover Units.
In vehicle mode, this model relies on four wheels for mobility, but it can shift into a bipedal mode, with the axles forming arms and legs, and the tires serving as ankle and wrist joints. Though its cockpit is similarly to its flight-bound brethren, it is only large enough to accommodate a single Mobian/Robian driver. It presumably runs from an onboard AI. This model also possesses a laser cannon on the underside as opposed to the roof like the Hover Units.