Abstract: A foldable rotor system for a rotorcraft, the foldable rotor system comprising a rotor assembly operably associated with a driveshaft, the driveshaft being operable associated with an engine, the rotor assembly comprising a rotor blade connected to a grip pin. A swashplate is operable associated with the grip pin in order selectively change a pitch of the rotor blade. A blade fold actuator is operably associated with the grip pin such that the blade fold actuator is configured to fold and unfold the rotor blade about a blade fold axis. During an airplane mode, the rotorcraft can stop and fold the rotor blades so that the rotorcraft relies upon thrust from the engine for propulsion. The rotor blades are folded in a spiral fold path so that the rotor blades remain substantially edgewise, or feathered, during the folding process. The spiral fold path minimizes the aerodynamic drag experienced by the rotor blades while being folded during flight of the rotorcraft.

Abstract: A ducted fan for a helicopter includes a transverse duct and a counter-torque device supported within the duct. The counter-torque device includes a rotor rotatably mounted within the duct and a stator fixedly mounted within the duct downstream from the rotor. The rotor includes a rotor hub having a rotor axis, and rotor blades extending from the hub. The Rotor blades have a modulated angular distribution about the rotor axis. The stator includes a stator hub, and a plurality of stator vanes distributed around the stator hub. The stator vanes are angularly modulated around the stator hub.

Abstract: A ducted fan for a helicopter includes a transverse duct and a counter-torque device supported within the duct. The counter-torque device includes a rotor rotatably mounted within the duct and a stator fixedly mounted within the duct downstream from the rotor. The rotor includes a rotor hub having a rotor axis, and rotor blades extending from the hub. The Rotor blades have a modulated angular distribution about the rotor axis. The stator includes a stator hub, and a plurality of stator vanes distributed around the stator hub. The stator vanes are angularly modulated around the stator hub.

Abstract: A foldable rotor system for a rotorcraft, the foldable rotor system comprising a rotor assembly operably associated with a driveshaft, the driveshaft being operable associated with an engine, the rotor assembly comprising a rotor blade connected to a grip pin. A swashplate is operable associated with the grip pin in order selectively change a pitch of the rotor blade. A blade fold actuator is operably associated with the grip pin such that the blade fold actuator is configured to fold and unfold the rotor blade about a blade fold axis. During an airplane mode, the rotorcraft can stop and fold the rotor blades so that the rotorcraft relies upon thrust from the engine for propulsion. The rotor blades are folded in a spiral fold path so that the rotor blades remain substantially edgewise, or feathered, during the folding process. The spiral fold path minimizes the aerodynamic drag experienced by the rotor blades while being folded during flight of the rotorcraft.

Abstract: A ducted fan for a helicopter includes a transverse duct and a counter-torque device supported within the duct. The counter-torque device includes a rotor rotatably mounted within the duct and a stator fixedly mounted within the duct downstream from the rotor. The rotor includes a rotor hub having a rotor axis, and rotor blades extending from the hub. The Rotor blades have a modulated angular distribution about the rotor axis. The stator includes a stator hub, and a plurality of stator vanes distributed around the stator hub. The stator vanes are angularly modulated around the stator hub.

Abstract: An exhaust system for an aircraft has a primary exhaust duct for communicating exhaust gas from an engine exhaust exit and is configured for movement with the engine. A secondary exhaust duct is in fluid communication with the primary exhaust duct and is movably mounted to the airframe. The secondary duct has a portion selectively rotatable relative to the remainder of the secondary duct for directing the exhaust gas vector. The system has means for maintaining a generally consistent relative alignment between the primary duct and the secondary duct.

Abstract: An exhaust system for an aircraft has a primary exhaust duct for communicating exhaust gas from an engine exhaust exit and is configured for movement with the engine. A secondary exhaust duct is in fluid communication with the primary exhaust duct and is movably mounted to the airframe. The system has means for maintaining a generally consistent relative alignment between the primary duct and the secondary duct.

Abstract: An exhaust system for an aircraft has a primary exhaust duct for communicating exhaust gas from an engine exhaust exit and is configured for movement with the engine. A secondary exhaust duct is in fluid communication with the primary exhaust duct and is movably mounted to the airframe. The secondary duct has a portion selectively rotatable relative to the remainder of the secondary duct for directing the exhaust gas vector. The system has means for maintaining a generally consistent relative alignment between the primary duct and the secondary duct.

Abstract: An exhaust system for an aircraft has a primary exhaust duct for communicating exhaust gas from an engine exhaust exit and is configured for movement with the engine. A secondary exhaust duct is in fluid communication with the primary exhaust duct and is movably mounted to the airframe. The system has means for maintaining a generally consistent relative alignment between the primary duct and the secondary duct.

Abstract: A ducted fan for a helicopter includes a transverse duct and a counter-torque device supported within the duct. The counter-torque device includes a rotor rotatably mounted within the duct and a stator fixedly mounted within the duct downstream from the rotor. The rotor includes a rotor hub having a rotor axis, and rotor blades extending from the hub. The Rotor blades have a modulated angular distribution about the rotor axis. The stator includes a stator hub, and a plurality of stator vanes distributed around the stator hub. The stator vanes are angularly modulated around the stator hub.

Abstract: A rotorcraft having an enhanced configuration in which a simple wing and a propulsive anti-torque system are combined is disclosed. The propulsive anti-torque system includes an anti-torque thruster system in which a variable pitch fan is installed internal to the tail boom of the rotorcraft and an anti-torque thruster nozzle is mounted at the extremity of the tail boom. The fan is driven directly from the main rotor drive. The configuration and location of the fan allows the primary exhaust from the engine to be mixed with the compressed air flow from the fan. The mixed air flow from the fan and the engine passes through the tail boom and out the thruster nozzle.

Abstract: A damper has a piston having an axis, an outer surface, and opposing ends. Elastomeric seals are in sealing contact with the outer surface of the piston, the seals being coaxial with the piston and limiting movement of the piston to a path along the axis of the piston. The seals also define fluid chambers adjacent the ends of the piston. A primary passage communicates the fluid chambers, and a selectively switchable valve for controls a flow of fluid from one of the chambers to another of the chambers through the primary passage. When the flow of fluid through the primary passage is permitted, movement of the piston is resisted by a first spring rate due to a shear force required to cause shear deflection of the seals. When the flow of fluid through the primary passage is restricted, movement of the piston is resisted by a second spring rate due to a fluid force required to cause bulging deflection of the seals.

Abstract: A proprotor blade (27a, 27b, 127a, 127b) having a fixed, spanwise, leading edge slot (215) located in at least the inboard portion of the proprotor is disclosed. The slot (215) is formed by a selectively shaped slat (217) disposed in a selectively shaped recessed area (219) located at the leading edge (202) of the main portion of the proprotor blade. The slot (215) is selectively shaped so the a portion of the airflow over the lower airfoil surface of the proprotor blade is diverted between the main portion of the proprotor blade and the slat (217) and exits at the upper airfoil surface of the proprotor blade. The present invention may be used on both military-type tiltrotor aircraft (11) and civilian-type tiltrotor aircraft (111) with only minor variations to accommodate the different shapes of the proprotor blades.