846. Use of Mass Properties Data to Assess Engine Performance


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T Goyette: 846. Use of Mass Properties Data to Assess Engine Performance. 1970.



Early Titan IIIC flight data indicated problems with large outages on the third stage (transtage). The accuracy of the data used to establish outage for these flights was questioned. A search was established for a different data source to verify the validity of the large outages. As a result, an alternative technique for evaluating third stage performance (mixture ratio and outage) from mass properties data was developed. The technique used the side-by-side propellant tanks and the effects of the propellants contained therein on center of gravity location to determine inflight propellant consumption, inflight mixture ratio and outages. Tracking the center of gravity location was accomplished by evaluating yaw guidance error command (relative position of the thrust vector). By comparing the preflight predicted center of gravity location versus time from mass properties reports with center of gravity location versus time during flight, engine performance assessment was achieved. The technique was shown to be as accurate as level sensors for determining outage and with refinements could be made more accurate than level sensors.


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