Abstract: A multi-ratio rotorcraft drive system and a method of changing gear ratios thereof are disclosed. According to one embodiment, the multi-ratio rotorcraft drive system comprises a rotor system comprising one or more rotors and one or more engines. Each engine of the one or more engines is coupled to the rotor system through a multi-ratio transmission. The multi-ratio transmission comprises an output shaft coupled to the rotor system, an input shaft coupled to a respective engine of the one or more engines, a high speed clutch integrated into a high speed gear train, and a low speed clutch integrated into a low speed gear train. The high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft.

Abstract: A multi-ratio rotorcraft drive system and a method of changing gear ratios thereof are disclosed. According to one embodiment, the multi-ratio rotorcraft drive system comprises a rotor system comprising one or more rotors and one or more engines. Each engine of the one or more engines is coupled to the rotor system through a multi-ratio transmission. The multi-ratio transmission comprises an output shaft coupled to the rotor system, an input shaft coupled to a respective engine of the one or more engines, a high speed clutch integrated into a high speed gear train, and a low speed clutch integrated into a low speed gear train. The high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft.

Abstract: A multi-ratio rotorcraft drive system and a method of changing gear ratios thereof are disclosed. According to one embodiment, the multi-ratio rotorcraft drive system comprises a rotor system comprising one or more rotors and one or more engines. Each engine of the one or more engines is coupled to the rotor system through a multi-ratio transmission. The multi-ratio transmission comprises an output shaft coupled to the rotor system, an input shaft coupled to a respective engine of the one or more engines, a high speed clutch integrated into a high speed gear train, and a low speed clutch integrated into a low speed gear train. The high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft.

Abstract: A multi-ratio rotorcraft drive system and a method of changing gear ratios thereof are disclosed. According to one embodiment, the multi-ratio rotorcraft drive system comprises a rotor system comprising one or more rotors and one or more engines. Each engine of the one or more engines is coupled to the rotor system through a multi-ratio transmission. The multi-ratio transmission comprises an output shaft coupled to the rotor system, an input shaft coupled to a respective engine of the one or more engines, a high speed clutch integrated into a high speed gear train, and a low speed clutch integrated into a low speed gear train. The high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft.

Abstract: A hydraulic actuator has an armored section having concentric cylinders and an unarmored section having a cylinder with a frangible piston and a frangible upper gland nut. The hydraulic actuator may have leakage vents adapted to prevent leakage between hydraulic systems used to power the cylinders. The hydraulic actuator also may have a gland seal for sealing an end of the cylinder of the unarmored section and a sensing port adapted for allowing detection of fluid leaking due to damage of the gland seal.

Abstract: A multi-ratio rotorcraft drive system and a method of changing gear ratios thereof are disclosed. According to one embodiment, the multi-ratio rotorcraft drive system comprises a rotor system comprising one or more rotors and one or more engines. Each engine of the one or more engines is coupled to the rotor system through a multi-ratio transmission. The multi-ratio transmission comprises an output shaft coupled to the rotor system, an input shaft coupled to a respective engine of the one or more engines, a high speed clutch integrated into a high speed gear train, and a low speed clutch integrated into a low speed gear train. The high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft.

Abstract: A mechanical flight control system for a rotary-wing aircraft is disclosed. The flight control system comprises an upstream portion, a downstream portion, and an assembly for connecting the upstream portion to the downstream portion. The assembly may comprise dual concentric valve actuators and/or a variety of system load limiting features.

Abstract: A mechanical flight control system for a rotary-wing aircraft is disclosed. The flight control system comprises an upstream portion, a downstream portion, and an assembly for connecting the upstream portion to the downstream portion. The assembly may comprise dual concentric valve actuators and/or a variety of system load limiting features.

Abstract: A hydraulic actuator is configured to provide redundant boost control to an aircraft within approximately the same space required by a single hydraulic cylinder. The hydraulic actuator includes a housing and a piston assembly disposed within the housing. The piston assembly includes a ram, a first piston secured to the ram, and second and third pistons disposed on the ram such that the second and third pistons are translatable relative to the longitudinal axis of the ram. The pistons form two hydraulically separate actuator cylinders within the space required by a single cylinder which results in a reduction in the weight and size of the hydraulic actuator.

Abstract: A multi-ratio rotorcraft drive system and a method of changing gear ratios thereof are disclosed. According to one embodiment, the multi-ratio rotorcraft drive system comprises a rotor system comprising one or more rotors and one or more engines. Each engine of the one or more engines is coupled to the rotor system through a multi-ratio transmission. The multi-ratio transmission comprises an output shaft coupled to the rotor system, an input shaft coupled to a respective engine of the one or more engines, a high speed clutch integrated into a high speed gear train, and a low speed clutch integrated into a low speed gear train. The high speed clutch and the low speed clutch are freewheeling clutches without a friction plate and are capable of disconnecting the output shaft and the input shaft in an overrunning condition when the output shaft spins faster than the input shaft.

Abstract: An actuator control system has a dual concentric servo valve having a spool and at least one motor adapted to selectively displace the spool.

Abstract: A mechanical flight control system for a rotary-wing aircraft is disclosed. The flight control system comprises an upstream portion, a downstream portion, and a booster means for connecting the upstream portion to the downstream portion. The booster means may comprise dual concentric valve actuators and/or a variety of system load limiting features.

Abstract: A hydraulic actuator is configured to provide redundant boost control to an aircraft within approximately the same space required by a single hydraulic cylinder. The hydraulic actuator includes a housing and a piston assembly disposed within the housing. The piston assembly includes a ram, a first piston secured to the ram, and second and third pistons disposed on the ram such that the second and third pistons are translatable relative to the longitudinal axis of the ram. The pistons form two hydraulically separate actuator cylinders within the space required by a single cylinder which results in a reduction in the weight and size of the hydraulic actuator.

Abstract: A hydraulic actuator has an armored section having concentric cylinders and an unarmored section having a cylinder with a frangible piston and a frangible upper gland nut. The hydraulic actuator may have leakage vents adapted to prevent leakage between hydraulic systems used to power the cylinders. The hydraulic actuator also may have a gland seal for sealing an end of the cylinder of the unarmored section and a sensing port adapted for allowing detection of fluid leaking due to damage of the gland seal.

Abstract: A control system for a rotorcraft is disclosed. The control system includes a stepped mixing linkage, such that a selected amount of right-left lateral cyclic output is generated for certain amounts of forward-aft cyclic input. The stepped mixing linkage includes two supporting links and a floating link pivotally coupled between the two supporting links. The ratio of the lengths of the two supporting links to the length of the floating link is small, thereby generating a selected lateral sinusoidal output, a selected rotation of the sinusoidal output, and a selected ramped output in response to each forward-aft pilot input command.

Abstract: An actuator control system has a dual concentric servo valve having a spool and at least one motor adapted to selectively displace the spool.

Abstract: A mechanical flight control system for a rotary-wing aircraft is disclosed. The flight control system comprises an upstream portion, a downstream portion, and a booster means for connecting the upstream portion to the downstream portion. The booster means may comprise dual concentric valve actuators and/or a variety of system load limiting features.

Abstract: A two-stage pressure relief valve for use with hydraulic systems is disclosed. The two-stage pressure relief valve has a first stage that relieves increases in hydraulic system pressure over the normal operating pressure and up to a selected threshold pressure level, and a second stage that brings the hydraulic system pressure down to a selected reduced operating pressure that is below the normal operating pressure in response to increases in the operating pressure over the threshold pressure level.

Abstract: A control system for a rotorcraft is disclosed. The control system includes a stepped mixing linkage, such that a selected amount of right-left lateral cyclic output is generated for certain amounts of forward-aft cyclic input. The stepped mixing linkage includes two supporting links and a floating link pivotally coupled between the two supporting links. The ratio of the lengths of the two supporting links to the length of the floating link is small, thereby generating a selected lateral sinusoidal output, a selected rotation of the sinusoidal output, and a selected ramped output in response to each forward-aft pilot input command.

Abstract: An integrated three function valve (ITFV) that combines the functions of a bypass valve (e.g. 183a, 185a, 161a) into a single assembly is disclosed. The ITFV allows continued operation after any two failures.