Self-Propelled Heavy Artillery
The Self-Propelled Heavy Artillery (SPHA) walker, also referred to as the Mobile Assault Cannon (MAC), functioned as a customizable heavy artillery platform. It saw service with the Grand Army of the Republic during the Clone Wars and continued its service under the Galactic Empire afterwards. This artillery unit shared visual similarities with the smaller RX-200 Falchion, which was also deployed by the Republic forces during the Clone Wars. Depending on its specific loadout, the walker was designated with different names: SPHA-T (turbolaser), SPHA-I (ion cannon), SPHA-V (anti-vehicle laser), SPHA-C (concussion missile launcher), SPHA-M (mass-driver cannon) and SPHA-F (thermobaric cannon).
Description
The SPHA, or Self-Propelled Artillery Walker, utilized a dozen legs to achieve mobility and stability. Due to their significant size and weight, SPHA units could not be transported by LAAT/c gunships, unlike smaller walkers like the AT-TE. Instead, these artillery platforms were deployed directly from landed Acclamator-class assault ships, each capable of carrying 36 SPHAs.
During combat operations, SPHA walkers typically received their instructions from ground-based command centers. These command posts offered a broader and more connected perspective on the battlefield compared to the elevated and isolated viewpoint from within the walkers. Moreover, each SPHA unit included a complement of 30 clone troopers who could be rapidly deployed through a hatch located on the dorsal side of the walker. These soldiers could quickly exit the vehicle and secure the immediate vicinity of the walker, providing defense against enemy infantry and lighter combat units.
Main weapons
The SPHA walker's chassis served as a foundation for various weapon configurations, with the turbolaser (SPHA-T) variant being the most documented. The primary weapon of this version was a heavy turbolaser cannon, designed to inflict substantial direct damage on large or slow-moving targets. This turbolaser possessed exceptional range and the ability to penetrate deflector shields.
A key limitation of this potent weapon was its inability to provide indirect fire support to targets obscured from direct view. This issue was addressed in other SPHA models. Another drawback was the weapon's charging mechanism; after firing a fully charged shot, the depleted gun had to be replaced with a pre-charged one from the rear lines.
Other variants deployed during the Clone Wars included the ion cannon (SPHA-I), anti-vehicle laser (SPHA-V), concussion missile (SPHA-C), thermobaric burst (SPHA-F), and mass-driver (SPHA-M) versions. Certain model variations were equipped with 12 retractable antipersonnel blasters, increasing the command crew size by 10 gunners, in addition to the original crew of 15.
History
Development
Rothana Heavy Engineering was responsible for the development of the SPHA walker.
The power demands of the turbolaser cannon in the SPHA-T variant significantly influenced the design of the vehicle's other components.
Instead of a complex turret system, the designers opted for a design where the entire walker would reposition itself to adjust firing angles. Similar to other walkers, the articulated legs of the SPHA provided resistance to anti-repulsorlift weaponry, albeit at the expense of some maneuverability.
Later, the Galactic Empire engineered a more compact successor, the SPMA. The SPMA offered enhanced mobility and a smaller footprint due to advancements in weight-reduction technologies.
Usage
The SPHA, particularly the SPHA-T variant, made its debut during the First Battle of Geonosis. It played a crucial role in the destruction of several Lucrehulk-class core ships and Hardcell-class interstellar transports.
SPHA units saw widespread use throughout the Clone Wars, participating in ground battles such as the Battle of Cato Neimoidia, the Battle of Muunilinst (where numerous units were destroyed by the agile IG lancer combat droids), the Battle of Rhen Var, and the Second Battle of Tatooine.
Following a suggestion from Anakin Skywalker, numerous Venator-class Star Destroyers belonging to the Open Circle Fleet were outfitted with SPHA-T turbolaser cannons installed within their ventral hangar bays. These proved highly effective during the Battle of Coruscant, particularly against enemy Munificent-class star frigates.
The SPHA line of walkers remained in service during the early years of the Galactic Empire, until the development of the SPMA line. The SPMA vehicles offered greater speed and maneuverability compared to the more cumbersome SPHA-Ts.
Behind the scenes
Erik Tiemens, the Concept Design Supervisor, created the concept art for the SPHA-T. Initially, he envisioned a tracked vehicle, but George Lucas requested a walker design. The SPHA was originally designated "Clone Tank A" during production.
In both Star Wars: Attack of the Clones: The Visual Dictionary and Star Wars: The Complete Visual Dictionary, the SPHA-T's turbolaser is mistakenly identified as a troop hatch. Furthermore, The New Essential Guide to Vehicles and Vessels incorrectly describes the SPHA-T as being propelled by multiple treads. In reality, it is a walker that utilizes twelve legs for locomotion.
The vehicle's precise size remains ambiguous, as the 140-meter length cited in The Official Star Wars Fact File 71 does not align with the scale depicted in Star Wars: Episode II Attack of the Clones or the dimensions presented in The New Essential Guide to Vehicles and Vessels.