RX-75-4 Guntank

The RX-75-4 Guntank was a prototype long-range artillery mobile suit developed by the Earth Federation Forces. It was the first of three mobile suits produced under Project V, alongside the RX-77-2 Guncannon and RX-78-2 Gundam.

The “R” in the type code meant it was a Federation model¹ and the “X” designated it as an experimental mobile suit. The model number “75” indicated it was from the RX-75 Guntank line. The block number “4” meant it was the fourth design revision.

The Guntank was designed for long-range fire support and artillery bombardment. Unlike traditional mobile suits, its lower body consisted of caterpillar treads rather than legs, trading mobility for stability and firepower. This unique configuration made it ideal for stationary defensive positions and sustained bombardment operations.

History

The Earth Federation initiated Project V in UC 0075 after receiving intelligence about the Principality of Zeon’s mobile suit development programme. The project aimed to develop three complementary mobile weapon systems, each specialised for different combat ranges.

The Guntank was the first unit to be completed in March UC 0079, six months before the outbreak of the One Year War. As the earliest Project V machine, it served as a testbed for many technologies that would be refined in its successors. Its tracked lower body was a compromise solution, as the Federation had not yet perfected bipedal locomotion systems for heavy artillery platforms.

Two Guntank units were deployed to Side 7 for final testing and refinement. When Zeon forces attacked the colony on 18 September UC 0079, both units were evacuated aboard the assault carrier White Base.

During the White Base’s journey, the Guntanks served as long-range fire support units, providing covering fire whilst the more mobile Guncannon and Gundam engaged enemy forces directly. Their powerful cannons proved effective against Zeon forces, though their limited mobility made them vulnerable in close-quarters combat.

One Guntank was destroyed during the battle at the Urubamba Gorge in South America when the Black Tri-Stars attacked the White Base. The unit, piloted by Ryu Jose, was overwhelmed by the coordinated assault of three MS-09 Dom mobile suits using their signature Jet Stream Attack.

The surviving Guntank continued to serve until the final battle at A Baoa Qu in December UC 0079, where it was eventually destroyed. Despite its limitations, the Guntank proved the viability of mobile weapons for artillery roles and influenced the design of later Federation mobile suits.

Design

The RX-75-4 Guntank represented the Federation’s first attempt at creating a mobile artillery platform. Its unconventional design combined the firepower of a self-propelled artillery piece with the flexibility of a mobile weapon system.

Unlike the Guncannon and Gundam, the Guntank used caterpillar treads for its lower body rather than legs. This design decision was driven by practical concerns—the Federation had not yet perfected the complex leg mechanisms required for heavy artillery units. The tracked configuration provided exceptional stability for long-range bombardment and could support the weight of the unit’s substantial armament.

The Guntank’s upper body housed the cockpit and primary weapons systems. Two 120 mm cannons replaced conventional manipulator arms, whilst a rotating turret mounting twin 240 mm cannons sat atop the shoulders. This arrangement gave the Guntank devastating long-range firepower, though it severely limited close-quarters combat capability.

The unit’s armor consisted of Luna Titanium alloy, the same lightweight yet durable material used on its Project V siblings. Whilst this provided good protection against conventional weapons, the Guntank’s tracked lower body was more vulnerable than a mobile suit’s legs, particularly to attacks targeting the treads themselves.

The Guntank’s Minovsky fusion reactor had a lower output than the Guncannon or Gundam, reflecting its role as a support unit rather than a frontline combatant. Its tracked locomotion system was also slower than bipedal mobile suits, with a maximum speed of only 70 km/h on flat terrain. However, this was considered acceptable for its intended role as a long-range artillery platform.

Armaments

The RX-75-4 Guntank’s standard weapons were its shoulder-mounted 240 mm cannons for long-range bombardment, supplemented by arm-mounted 120 mm cannons for medium-range fire. This heavy artillery loadout made it the most powerful long-range combatant among the Project V machines.

240 mm cannons

The Guntank’s primary weapons were twin 240 mm cannons mounted in a rotating turret on its shoulders. These weapons provided the unit with exceptional long-range firepower, capable of engaging targets at distances far beyond the effective range of most mobile suit weapons.

The cannons fired high-explosive shells that could devastate enemy formations and fortifications. Their elevated mounting position gave them excellent firing arcs, allowing the Guntank to provide indirect fire support from protected positions. The turret could rotate 360 degrees, giving the Guntank full coverage without needing to reposition its entire body.

The ammunition capacity for the 240 mm cannons was substantial, allowing for sustained bombardment operations. However, the cannons required time to reload between salvos, making them less effective against fast-moving targets.

120 mm low-recoil cannons

In place of conventional manipulator arms, the Guntank mounted twin 120 mm low-recoil cannons. These weapons served as the unit’s medium-range armament, effective for engaging enemy mobile suits at closer distances than the shoulder cannons.

The low-recoil design allowed the Guntank to fire these weapons whilst maintaining stability, even on uneven terrain. The cannons were fixed-forward, requiring the entire unit to turn to engage targets. This limitation was acceptable given the Guntank’s role as a support unit rather than a frontline combatant.

Each 120 mm cannon had a high rate of fire compared to the shoulder-mounted weapons, making them effective for suppressive fire and engaging multiple targets in rapid succession.

60 mm vulcan guns

Like its Project V siblings, the Guntank mounted twin 60 mm vulcan guns in its head. These rapid-fire weapons were primarily used for point defence against incoming missiles and light-armored vehicles.

Each vulcan gun held 400 rounds of ammunition and could fire at 1,600 rounds per minute. Whilst ineffective against mobile suit armor, they proved useful for engaging infantry, aircraft, and support vehicles.

4-tube missile launchers

The Guntank carried two 4-tube missile launchers mounted on its torso. These weapons provided additional firepower for saturation bombardment or engaging multiple targets simultaneously.

The missiles were unguided but could be fired in salvos to blanket an area with explosives. This made them particularly effective against enemy formations or fortified positions.

Beam rifle

Despite its artillery focus, the Guntank could be equipped with a standard Federation beam rifle for emergency close-range combat. However, the lack of manipulator arms made wielding the weapon awkward, requiring special mounting brackets. In practice, this weapon was rarely used, as the Guntank was typically positioned far from close-quarters engagements.

Known pilots

• Hayato Kobayashi
• Ryu Jose

Variants

The RX-75-4 Guntank was preceded by the RX-75 Guntank, an earlier prototype that established the basic tracked configuration. Following the One Year War, the design influenced several descendant units:

The RTX-65 Guntank Early Type was a proposed mass-production variant that saw limited deployment. The RMV-1 Guntank II was developed years later, incorporating lessons learned from the original’s combat performance whilst adding improved mobility systems.

Behind the scenes

The RX-75-4 Guntank was designed by Kunio Okawara for the original Mobile Suit Gundam television series. Its unique tracked design made it instantly recognisable among the Project V machines and represented a transitional step in the Federation’s mobile weapon development.

The Guntank’s design drew inspiration from real-world self-propelled artillery and the concept of walking tanks from earlier science fiction. Its tracked lower body was both a practical design choice for the animation production and a narrative element showing the Federation’s gradual mastery of mobile suit technology.

The unit has been featured in numerous Gundam model kits:

• High Grade Universal Century (HGUC)
  • 1/144 RX-75-4 Guntank (2002)
  • 1/144 RX-75-4 Guntank (Revive) (2021)
• Master Grade (MG)
  • 1/100 RX-75-4 Guntank (2005)
• Real Grade (RG)
  • None produced

Appearances

Anime

• Mobile Suit Gundam
• Mobile Fighter G Gundam (episode 48, cameo)

Films

• Mobile Suit Gundam I
• Mobile Suit Gundam II: Soldiers of Sorrow
• Mobile Suit Gundam III: Encounters in Space

OVAs

• Mobile Suit Gundam MS IGLOO: The Hidden One Year War (episode 3)
• Gundam: Battlefield Record - Avant-title

Games

The Guntank has appeared in numerous Gundam video games, including the Federation vs. Zeon series, Dynasty Warriors: Gundam series, and various Gundam vs arcade games.

See also

• Project V
• RX-77-2 Guncannon
• RX-78-2 Gundam
• Earth Federation mobile suits in Mobile Suit Gundam

External links

• RX-75-4 Guntank on the Gundam Wiki

Footnotes

1. Federation in Japanese is renpou, hence the use of “R”. ↩