Shown here is the post-boost propulsion system for the Minuteman II intercontinental ballistic missile (ICBM). Unlike the solid-propellant lower stages, the post-boost system carried liquid propellants to help steer the missile. The system consists of small propellant tanks and a smaller helium tank to provide pressure to force the propellants into the combustion chambers.
Upon precise electronic commands, the system activates small bursts of thrust from four equidistant nozzles around the wall of the missile, thereby correctiing its attitude.
Bell Aerosystems donated the post-boost propulsion system to the Smithsonian in 1968.
Bell Aerosystems Co,