The Rocketdyne LR89 was a liquid-fueled rocket engine developed in the 1950s by Rocketdyne, a division of North American Aviation. It was designed to serve as a booster engine the Atlas rocket family.[1][2][3][4] The LR89 was a liquid oxygen (LOX) and RP-1 (kerosene) engine.[5]
It was used in configurations where it worked alongside the LR105 sustainer engine to enhance thrust in the first stage of the Atlas, being jettisoned when the vehicle weight had been considerably reduced due to propellant consumption.[5][6]