Webb, W. W. | Engineering Papers

NASA NTRS1976

Dynamic control of SRB thrust tailoff for separation

The use of the difference in chamber pressure between solid rocket booster engines as a controlling signal to the flight control system during booster thrust tailoff was examined. In addition, the control capability of the Generalized Attitude Control System (GACS) was compared to that of the baseline. Results indicate that the difference in chamber pressure signal provided essentially no improvement. However, the GACS is considerably better than the baseline in controlling during tailoff disturbances.

Webb, W. W.↗

NASA NTRS1975

Roll maneuver evaluation

The current roll maneuver to the flight azimuth following lift-off is achieved by commanding roll attitude using a linear profile with no roll rate command. The linearity of this command profile implies an infinite acceleration to a constant roll rate; the vehicle cannot instantaneously achieve this rate, so the actual roll attitude lags the command attitude throughout the maneuver. The roll attitude error which thus develops can be reduced by augmenting the attitude command with a rate command and utilizing finite slopes on the rate command to give the vehicle time to accelerate. Results obtained from commanding various roll attitude and rate combinations to perform the maneuver are presented.

Webb, W. W.↗