ADDJUST-A View of the First 25 Years

Abstract

Various technologies and innovative launch operations were developed during the 50 years of the Centaur upper stagethe first launch vehicle to use high performing liquid hydrogen fuel. One innovation was ADDJUST, which enabled the successful negotiation of upper level winds measured only hours before launch. Initial causes for its creation, development, and operation during countdown are detailed. Problem definition, wind measuring/monitoring process, pitch and yaw steering coefficient generation, loads analysis, angle of attack, major risks/concerns, and anecdotal recollections are provided. Launch availability improved from as low as 55 to 95 percent due to ADDJUST, which is still in use