PROGRAMS:

COMPANIES:

• North American Aviation
• Rocketdyne

LOCATIONS:

Rocketdyne, Canoga Park, CA

COMMENTS:

Larry Sack was responsible for engine transient analysis for the Space Shuttle Main Engine.  The SSME was the first computer controlled rocket engine and had the requirement to throttle down during max Q and then return to normal thrust with the capability of going to a still higher emergency power level if necessary. As a staged combustion engine, control during transient operation is particularly difficult. The transient analysis required much greater detail and accuracy than previous engines.  Larry’s analysis established the parameters for the control design for the engine including valve requirements and settings.  The proof of the excellence of the analysis was shown by the flight record and later deep throttling tests in support of the single stage to orbit program in which an SSME was rum from full thrust to one percent of full thrust and then back to full thrust with no problems.