SP42 Cobra

The Special Purpose-42 Main Battle Tank, commonly known as the Cobra, is a hybrid anti-matériel and anti-fortification vehicle built by Misriah Armory. It was adopted into Colonial Military Authority (CMA) service in 2497, though most units were eventually transferred into United Nations Space Command (UNSC) control during the Human-Covenant War.

Design details
Despite the Cobra's classification as a main battle tank it is designed to be lightly armored, fast, and maneuverable. Unlike most tanks the SP42 uses six all-terrain wheels that enable impressive mobility even over rough terrain and are protected by pivoting front and rear wheel guards. The two rear wheels are retracted when the vehicle enters lockdown mode. They are designed to supplement more standard tanks such as the M808 Scorpion by serving as a more agile tank hunter and mobile gun system.

The Cobra can be upgraded with additional hardened steel deflection plating on the sides of the turret to provide extra protection while in its locked-down state.

Armament
The SP42 MBT is equipped with a pair of turret-mounted 16MJ M66 30mm light railguns that fire high-density ferrous slugs; these slugs are twice the size of those used by the M68 Gauss cannon and are designed to penetrate enemy armor using sheer kinetic energy. The railguns fire intermittently, not in a single burst, as the energy required to accelerate the slugs to the speeds required to pierce the heaviest armor can only be managed for one of the cannons at a time. Synchronized fire from both railguns can destroy even the most heavily armored tank, with penetration that easily outguns the M808 Main Battle Tank's standard M512 90mm cannon.

In addition to the Cobra's anti-vehicle role the tank can be stabilized upon the ground, "locking down", and deploy a 8MJ M98 105mm light railgun which fires a conventional explosive shell at supersonic velocities. The explosive and kinetic forces of the shell complement each other to increase the damage inflicted. An M98's shell, when specially outfitted, can penetrate a 's energy shield and destroy the platform; a single shot can likewise disable the shields occasionally outfitted on the  and deal minor damage to the hull. Massed fire from several M98s can quickly destroy even a Covenant citadel, a massive structure outfitted with starship-grade armor plating.

Operational history
The SP42 Cobra was first deployed in 2497 during Operation: CHARLEMAGNE, as a supplement of the M808 Scorpion. Most of the production units were later inherited from the CMA by the UNSC during the Human-Covenant War, but would their production was not continued. They saw use among the ground complement of during the vessel's campaigns in early 2531, seeing action in the Harvest campaign, Battle for Arcadia and Battle of Trove.

Halo Wars
The Cobra can be produced at the Vehicle Depot from at a cost of  and. It can be upgraded with the following enhancements:
 * Deflection Plating - gives the Cobra extra protection. Cost.
 * Piercing Shot - enables railgun to penetrate multiple targets, damaging each. Cost.

Trivia

 * Like most UNSC vehicles the Cobra is superficially similar to its animal namesake. When locked down the SP42 MBT lowers itself and becomes poised to fire; this is similar to actual cobras, which typically coil before striking. The vehicle is especially similar to the spitting cobra, which can project venom to great distances.
 * The Cobra's artillery mode has an uncanny resemblance to the Terran siege tank from Starcraft, which can transform from tank mode to siege mode, with a sacrifice of mobility for longer range and greater firepower.
 * Despite its designation as a main battle tank, the Cobra is technically a hybrid self-propelled gun and tank destroyer. The "tank" moniker is likely an in-universe misnomer or simplification, as with the M9 Wolverine.

List of appearances

 * Halo Wars