The SIE-TIE twin ion engine, an ion drive, was engineered by Sienar Advanced Systems, under the leadership of Raith Sienar, near the end of the Separatist Crisis. This engine served as a developmental prototype for the P-s4 twin ion engine that was later implemented in TIE Series starfighters.
Raith Sienar conceived the SIE-TIE engine. It employed microparticle accelerators to energize ionized gases, propelling them to near-light speeds. Furthermore, it incorporated independently controlled ion stream deflector manifolds, which allowed for extremely precise maneuvering. To augment power output, it also included solar collection panels, a feature that would become a defining characteristic of TIE fighter designs for many years.
Before the beginning of the Clone Wars, Republic Sienar Systems officially endorsed and adopted the SIE-TIE design. This announcement was conveyed to HoloNet News reporters on Lianna. The SIE-TIE was scheduled for large-scale production, making it available for purchase by the governing bodies of Republic member planets. The approval announcement caused Santhe/Sienar Technologies stock to immediately surge by 27.58 credits, and it was estimated that Raith Sienar's personal wealth increased by 640 million credits due to this stock market activity.
Despite the SIE-TIE's initial success, Republic Sienar Systems indicated that power-yield compatibility problems with existing hyperdrive, life support, and shielding systems could significantly hinder the engine's integration into their starship designs. This shortcoming persisted in the subsequent P-s4 model.