Abstract: A pilot-actuated spool valve comprises a generally cylindrical valve cage having a central axial cavity open at both ends and a plurality of generally radial openings connecting the central axial cavity to the external cylindrical surface of the cage; a valve sleeve sized to slide within the central axial cavity of the cage and having a first sealing surface at a first end and a second sealing surface at an opposing second end; a piston responsive to fluid pressure at a pilot inlet of the valve; a piston rod connected at a first end to the piston and having a threaded second end opposite the first end; and a cap nut in threaded engagement with the second end of the piston rod securing the valve sleeve to the piston rod. The cap nut is sized and configured to provide a clearance gap between the cap nut and the valve sleeve when the cap nut is fully tightened onto the threaded second end of the piston rod.

Abstract: A pilot-actuated spool valve comprises a generally cylindrical valve cage having a central axial cavity open at both ends and a plurality of generally radial openings connecting the central axial cavity to the external cylindrical surface of the cage; a valve sleeve sized to slide within the central axial cavity of the cage and having a first sealing surface at a first end and a second sealing surface at an opposing second end; a piston responsive to fluid pressure at a pilot inlet of the valve; a piston rod connected at a first end to the piston and having a threaded second end opposite the first end; and a cap nut in threaded engagement with the second end of the piston rod securing the valve sleeve to the piston rod. The cap nut is sized and configured to provide a clearance gap between the cap nut and the valve sleeve when the cap nut is fully tightened onto the threaded second end of the piston rod.

Abstract: A method and apparatus for controlling airflow with a gapped trailing edge device having a flexible flow surface. The airfoil can include a first portion having a first leading edge, a first flow surface, and a second flow surface facing opposite from the first flow surface. The airfoil can further include a second portion having a second leading edge and a trailing edge, with at least part of the second portion being positioned aft of the first portion. The second portion is moveable relative to the first portion between a first position and a second position, with the second leading edge separated from at least part of the first portion by an airflow gap when the second portion is in the second position. The second portion includes a flexible flow surface that has a first shape when the second portion is in the first position, and has a second shape different than the first shape when the second portion is in the second position.

Abstract: Trailing edge devices configured to carry out multiple functions, and associated methods of use and manufacture are disclosed. An external fluid flow body (e.g., an airfoil) configured in accordance with an embodiment of the invention includes a first portion and a second portion, at least a part of the second portion being positioned aft of the first portion, with the second portion being movable relative to the first portion between a neutral position, a plurality of upward positions, and a plurality of downward positions. A guide structure can be coupled between the first and second portions, and an actuator can be operatively coupled between the first and second portions to move the second portion relative to the first portion. In one embodiment, a flexible surface can track the motion of the second portion and can expose a gap at some positions.

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.

Abstract: A method and apparatus for controlling airflow with a gapped trailing edge device having a flexible flow surface. The airfoil can include a first portion having a first leading edge, a first flow surface, and a second flow surface facing opposite from the first flow surface. The airfoil can further include a second portion having a second leading edge and a trailing edge, with at least part of the second portion being positioned aft of the first portion. The second portion is moveable relative to the first portion between a first position and a second position, with the second leading edge separated from at least part of the first portion by an airflow gap when the second portion is in the second position. The second portion includes a flexible flow surface that has a first shape when the second portion is in the first position, and has a second shape different than the first shape when the second portion is in the second position.

Abstract: An airfoil assembly, such as a wing or horizontal stabilizer, has a gapped trailing-edge control surface and a door connected to the control surface by a linkage such that deflection of the control surface in one direction causes the door to pivot, thus opening an air flow slot for air to flow through. The air flow slot begins to open immediately with deflection of the control surface from its nominal position, thus establishing a desirable level of air flow to suppress separation on the control surface. The linkage connecting the control surface to the door is free of rolling or sliding elements, consisting exclusively of members pivotally connected to one another.

Abstract: 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.

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.

Abstract: An airplane having a fuselage (11), opposed main wings (12), and blunt-leading-edge raked wingtips (8) is provided. Each main wing includes an outboard end (9) and a leading edge (14) having an outboard end leading-edge nose and nose radius. One blunt raked wingtip (8) is located at each main wing outboard end (9) and includes a leading edge (20) swept back from the main wing leading edge (14). Each blunt raked wingtip (8) further includes a plurality of local airfoils each having a leading-edge nose radius and a chord. The nose radius is greater than about 2% of the local chord for the majority of the airfoils. The relative bluntness of the raked wingtips minimizes boundary-layer separation, drag associated with boundary-layer separation, and premature buffeting of the aircraft during low speed flight.