Aircraft tailstrike avoidance system
First Claim
1. In an aircraft flight control system having a normal pitch command signal provided to a pitch control device for altering the aircraft'"'"'s pitch attitude, an improvement for reducing the likelihood of an aircraft tailstrike, the improvement comprising:
- (a) determining a current tailskid height and a current tailskid closure rate wherein the current tailskid closure rate is determined at least in part by vertical speed of at least a part of the aircraft;
(b) comparing the current tailskid closure rate with a threshold closure rate to determine an excess closure rate amount, the threshold closure rate being dependent upon the current tailskid height; and
(c) adding an incremental nose-down pitch command signal to the normal pitch command signal to avoid a potential aircraft tailstrike, the incremental nose-down pitch command signal being calculated as a function of the excess closure rate amount.
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Abstract
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 attitude. 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.
27 Citations
20 Claims
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1. In an aircraft flight control system having a normal pitch command signal provided to a pitch control device for altering the aircraft'"'"'s pitch attitude, an improvement for reducing the likelihood of an aircraft tailstrike, the improvement comprising:
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(a) determining a current tailskid height and a current tailskid closure rate wherein the current tailskid closure rate is determined at least in part by vertical speed of at least a part of the aircraft;
(b) comparing the current tailskid closure rate with a threshold closure rate to determine an excess closure rate amount, the threshold closure rate being dependent upon the current tailskid height; and
(c) adding an incremental nose-down pitch command signal to the normal pitch command signal to avoid a potential aircraft tailstrike, the incremental nose-down pitch command signal being calculated as a function of the excess closure rate amount. - View Dependent Claims (4, 5, 6, 7, 9, 11, 13, 15, 16, 17, 18, 19, 20)
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2. In an aircraft flight control system having a normal pitch command signal provided to a pitch control device for altering the aircraft'"'"'s pitch attitude, an improvement for reducing the likelihood of an aircraft tailstrike, the improvement comprising:
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(a) determining a current tailskid height and a current tailskid closure rate wherein the current tailskid closure rate is determined at least in part by vertical speed of at least a part of the aircraft;
(b) comparing the current tailskid height with a threshold height to determine an excess height amount, the threshold height being dependent upon the current tailskid closure rate; and
(c) adding an incremental nose-down pitch command signal to the normal pitch command signal to avoid a potential aircraft tailstrike, the incremental nose-down pitch command signal being calculated as a function of the excess height amount. - View Dependent Claims (3, 8, 10, 12, 14)
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Specification