An improvement to an aircraft flight control system is provided for reducing the likelihood of an aircraft tailstrike. The flight control system includes a pitch command provided to a pitch control device for altering the aircraft's pitch attitute. The improvement is a system of altering the pitch command to avoid an aircraft tailstrike. The improvement includes determining a current tailskid closure rate and a current tail height; comparing the current tailskid closure rate with a threshold closure rate to determine an excess closure rate amount; and adding an incremental nose-down pitch command with the pitch command to avoid a potential aircraft tailstrike. The threshold closure rate is dependent upon the current tailskid height. The incremental nose-down pitch command is calculated as a function of the excess closure rate amount. An alternative embodiment is provided in which the current height is compared with a threshold height (that is a function of the current tailskid closure rate) to determine an excess height amount. The excess height is then used to form an incremental nose-down pitch command. Another embodiment is described using both height and rate thresholds to calculate the incremental nose-down pitch command. Alternative arrangements may be used in which other non-derivative and derivative values are used, e.g., pitch angle margin and pitch rate.
申请公布号
WO0140051(A3)
申请公布日期
2001.10.25
申请号
WO2000US32862
申请日期
2000.11.30
申请人
THE BOEING COMPANY
发明人
DEWITT, WENDI, M.;EGGOLD, DAVID, P.;EVANS, MONTE, R.;SANKRITHI, MITHRA, M., K., V.;WELLS, STEPHEN, L.