|Primary users||Soviet Union|
|Developed into||Rk-92 Savage|
The Rk-91 Savage is a second generation Arm Slave produced and operated by Soviet Union. It is the predecessor to the Rk-92 Savage. Despite being old by the start of the series, some are still in use.
After the use of the Rk-89 Shamrock in Afghanistan, in 1990, the more capable Rk-91 Savage was introduced, replacing the earlier AS almost entirely.
The Rk-91 Savage was the frontline AS of the Soviet Union, but the Rk-92 entered service shortly after it. Some pilots prefer the Rk-91 since its diesel piston engine is relatively quiet compared to the howling gas turbine engine of its successor. While the Soviet Union primarily uses the Rk-92 Savage, the Rk-89 Shamrock and the Rk-91 Savage remain in use. In the manga, Sousuke Sagara is seen using an Rk-91 Savage in underground combat.
- Crew: 1
- Height: 8.1 meters
- Power Source: Diesel engine, 1200hp