The Boeing Company

Monte R Evans

Kioumars Najmabadi

Edward E Coleman

Robert J Bleeg

Richard S Breuhaus

Timothy A Nelson

Dorr Marshall Anderson

Mithra M K V Sankrithi

David Paul Eggold

Stephen L Wells

Wendi M DeWitt

Antonius A Lambregts

Adam Marshall Thoreen

Timothy G Overton

Jonathan P Lee

Leo L Engstrom, Jr

Robert E Buchholz

Ross A Landes

Brian N Nield

The present invention provides a method of modifying the pitch attitude of an aircraft during landing, comprising: commanding the flaps to move to a landing setting; providing a current value for a flight condition parameter; providing a current flaps setting; comparing said current value to at least one threshold value; if said current value exceeds said threshold, determining a new flaps setting capable of producing an improvement in at least one of a selected aft body contact margin and a selected nose gear contact margin for the aircraft; and adjusting the flaps to said new flaps setting.

Quiet landing attitude modifier for airplane

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.

Aircraft tailstrike avoidance system

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 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.

A bias correction system for use in a neutrally-stable aircraft having a control column and a pitch control system is provided. The position of the control column is generally represented by a control column position signal. The bias correction system is for removing control column bias when the control column is in a neutral position. The bias correction system includes a first combining unit for combining the control column position signal and a correction signal, and a switch. The switch includes activated and deactivated states. The switch is set to the deactivated state when the control column is physically displaced from its neutral position. The deactivated state allows the correction signal to remain at its last value, the activated state allows the correction signal to equal approximately the control column position signal. In one embodiment, the bias correction system includes a smoothing filter for receiving the control column position signal and outputting a smoothed correction signal when the switch is in the activated state. In another embodiment, the bias correction system includes a unit for limiting the correction signal to control column position signal values within a limited predefined range.

Aircraft pitch-axis stability and command augmentation system

A method of providing speed protection to a neutrally-stable aircraft including the calculation of at least one of a stall protection signal and an overspeed protection signal. The aircraft includes a pitch control system having a command pitch signal received from pilot input to a control column. The protection signal is provided to the pitch control system to limit the commanded pitch signal during flight. The calculation of a stall protection signal includes differencing the aircraft's current airspeed with a reference speed and multiplying the difference by a scaling factor that corresponds to the force required by the pilot to move the control column. The calculation of an overspeed protection signal includes calculating a first signal based on airspeed, calculating a second signal based on Mach, selecting the large of the two signal and passing it through a limiter. The limiter is a function of roll attitude and corresponds to the force required by the pilot to move the control column. Also provided is a method of calculating a flare compensation signal to emulate ground effects encountered by an aircraft while executing a landing. The flare compensation signal is determined using a table of gear heights versus flare compensation amounts. The flare compensation signal is limited to a value between zero and a positive upper limit.

Method of speed protection and flare compensation for use with aircraft

Disclosed is a pitch-axis stability and command augmentation system (19) in which a pilot column input (.delta..sub.C) is provided to a pitch command processor (26), the output of which is a C*U feedforward command (C*U.sub.FFC) that is supplied as an additive input to a combining unit (20). The combining unit (20) receives a second additive input of an augmented feedback command signal (AFB.sub.COM). The resulting output is filtered and generates an elevator command signal (.delta..sub.e,FILT). The command processor (26) additionally supplies a corrected column position signal (.delta..sub.C,COR) to a pitch command C*U processor (26) that converts the corrected column position signal (.delta..sub.C,COR) into a C*U pitch command (C*U.sub.PilotCmd), representative of the pilot's requested elevator pitch which is generated by movement of the control column. A computed C*U processor (32) forms a computed C*U signal (C*U.sub.Computed) that is based on the current state of the aircraft. The C*U processor (32) includes a speed stability processor (150) that computes the difference between a reference speed (V.sub.REF) and calibrated airspeed (V.sub.CAS). The speed stability processor (150) includes phugoid damping (400) in generating a speed error signal (E.sub.z), and providing a means by which the pilot may set a reference airspeed (V.sub.REF) by using a trim device. An underspeed protection signal (C*U.sub.US) is supplied by a stall protection processor (416). A flare compensation signal (C*U.sub.FR) is supplied by a flare compensation processor (414). An overspeed protection processor (412) supplies an overspeed protection signal (C*U.sub.OS). A combining unit (424) is provided to combine the stall protection signal (C*U.sub.US), flare compensation signal (C*U.sub.FR), and overspeed protection signal (C*U.sub.OS) to form a compensation and protection signal (C*U.sub.C&P). A combining unit (22) combines the pilot-requested C*U command (C*U.sub.PilotCmd), the computed C*U signal (C*U.sub.Computed), and the compensation and protection signal (C*U.sub.C&P). The resulting signal is an error signal (E.sub.C*U) which is supplied to an integrator (28) that outputs a C*U integral command signal (IC*U.sub.COM). Another combining unit (23) receives the C*U integral command signal (IC*U.sub.COM) and combines it with a pitch rate damping command signal (Q.sub.COM). The output of the combining unit (23) is the augmented feedback command signal (AFB.sub.COM).

A number of different combinations of 'true/false' conclusions of the air/ground condition of an aircraft are analyzed and compared to automatically provide a signal to a flight control system of the aircraft to indicate whether the aircraft is in the air or on the ground, particularly during transition from air to ground or from ground to air.

System for providing an air/ground signal to aircraft flight control

A method modifying the landing pitch attitude of an airplane during landing approach and touchdown is disclosed. A reference value for a predetermined flight condition parameter is subtracted from a current value of the predetermined flight condition parameter, resulting in a difference value. Based upon the difference value, a schedule determines a corresponding deflection value for a movable surface capable of producing lift. The movable surface is automatically deflected to an amount equal to the deflection value. In alternative embodiments of the invention, the predetermined flight condition parameters include approach airspeed, attitude, and angle of attack.

Landing attitude modifier for airplane

Disclosed is a pitch-axis stability and command augmentation system (19) in which a pilot column input (.delta..sub.C) is provided to a pitch command processor (26), the output of which is a C*U feedforward command (C*U.sub.FFC) that is supplied as an additive input to a combining unit (20). The combining unit (20) receives a second additive input of an augmented feedback command signal (AFB.sub.COM). The resulting output is filtered and generates an elevator command signal (.delta..sub.e,FILT). The command processor (26) additionally supplies a corrected column position signal (.delta..sub.C,COR) to a pitch command C*U processor (26) that converts the corrected column position signal (.delta..sub.C,COR) into a C*U pitch command (C*U.sub.PilotCmd), representative of the pilot's requested elevator pitch which is generated by movement of the control cola. A computed C*U processor (32) forms a computed C*U signal (C*U.sub.Computed) that is based on the current state of the aircraft. The C*U processor (32) includes a speed stability processor (150) that computes the difference between a reference speed (V.sub.REF) and calibrated airspeed (V.sub.CAS). The speed stability processor (150) includes phugoid damping (400) in generating a speed error signal (E.sub.z), and providing a means by which the pilot may set a reference airspeed (V.sub.REF) by using a trim device. An underspeed protection signal (C*U.sub.Us) is supplied by a stall protection processor (416). A flare compensation signal (C*U.sub.FR) is supplied by a flare compensation processor (414). An overspeed protection processor (412) supplies an overspeed protection signal (C*U.sub.OS). A combining unit (424) is provided to combine the stall protection signal (C*U.sub.Us), flare compensation signal (C*U.sub.FR), and overspeed protection signal (C*U.sub.OS) to form a compensation and protection signal (C*U.sub.C&P). A combining unit (22) combines the pilot-requested C*U command (C*U.sub.PilotCmd), the computed C*U signal (C*U.sub.Computed), and the compensation and protection signal (C*U.sub.C&P). The resulting signal is an error signal (E.sub.C*U) which is supplied to an integrator (28) that outputs a C*U integral command signal (IC*U.sub.COM). Another combining unit (23) receives the C*U integral command signal (IC*U.sub.COM) and combines it with a pitch rate damping command signal (Q.sub.COM). The output of the combining unit (23) is the augmented feedback command signal (AFB.sub.COM).

Aircraft pitch-axis stability and command augmentation

A variable bandwidth factor KALT is applied in a total energy control system to obtain a reduction in throttle activity while maintaining system stability. The system has a total energy control loop and an energy distribution control loop. In the former, a net thrust command signal T.sub.c is generated to reduce the total energy error to zero. In the latter, an elevator position command signal .delta.e.sub.c is generated to reduce the energy rate distribution error, i.e. correct the distribution of energy between kinetic energy (speed) and potential energy (altitude). The error signal input into each loop has a flight path component and a speed component. The factor KALT is applied to both components of the total energy error to reduce the bandwidth of the total energy control loop with increasing altitude and thereby reduce throttle activity. The factor KALT is also applied to one of the components of the energy distribution error to prioritize reduction of that component to zero by control of elevator position. Preferably, speed control is prioritized, and energy errors are channeled into short term deviations in altitude.

Growing community of inventors

Federal Way, WA, United States of America

Monte R Evans