Abstract: A lock nut and tang washer mechanism preloads and locks components in a rotating environment. A drive system mechanism preloads and locks the device in a rotating environment and provides a double locking safety requirement needed in most aircraft for applications operating in an enclosed environment. The mechanism holds a required torque for the duration of the drive system operating life without the need for periodic visual inspections.

Abstract: A conversion system for a tiltrotor aircraft may be configured to control tilting of a pylon assembly relative to a wing of the aircraft. The system may include a means for generating asymmetric thrust with a propulsion rotor carried by the pylon assembly to generate a first torque on the pylon assembly in a first direction. The system may include a brake mechanism to selectively resist the first torque on the pylon assembly by applying a second torque to the pylon assembly in a second direction opposite the first direction. The rotor (via asymmetric thrust generated by the rotor) and the brake mechanism are coordinated to work against each other to control the tilt rate and angle of the pylon assembly during conversion between flight modes of the tiltrotor aircraft. Other aspects of the present technology include methods of tilting rotors of tiltrotor aircraft using asymmetric thrust and brake mechanisms.

Abstract: Embodiments of an environmental barrier and seal include physical shields to protect against mechanical damage, labyrinth features to inhibit fluid/particle intrusion, impeller features, and a brush seal. Combinations of these features are presented in various embodiments, specific to particular operating conditions, to create an environmental barrier that protects primary carbon face seals and other shaft seals.

Abstract: A shaft assembly (which may be a rotor mast for a rotorcraft) may include a shaft body formed with composite material and one or more metal fittings attached to the shaft body. A metal fitting may include an interior opening with a cross-section having a non-circular perimeter (such as an oval or an ellipse). The interior opening may also include contouring, such as a first tapered section in which the fitting converges toward the longitudinal axis of the shaft body and a second tapered section in which the fitting diverges from the longitudinal axis.

Abstract: A lightweight gearbox control mechanism for air cushion vehicles provides change in direction of rotation for the vehicle lift fan and allows the gearbox to be used at port or starboard vehicle locations without the use of specialty tools.

Abstract: A lock nut and tang washer mechanism preloads and locks components in a rotating environment. A drive system mechanism preloads and locks the device in a rotating environment and provides a double locking safety requirement needed in most aircraft for applications operating in an enclosed environment. The mechanism holds a required torque for the duration of the drive system operating life without the need for periodic visual inspections.

Abstract: A compact and unobtrusive rotor control mechanism is presented that provides collective and cyclic pitch change to both rotors of a coaxial rotor system as well as a differential collective pitch change to one or both rotors simultaneously.

Abstract: A rotor hub is presented that uses a low profile and frontal area design that reduces drag and combines the advantages of utilizing a virtual flapping hinge and a soft in-plane rotor hub.

Abstract: A dual, coaxial rotor helicopter is provided that is relatively easy to fly. Thrust is provided by two ducted fans that are mounted at the rear of the aircraft and spaced apart laterally. Differential thrust generated by the fans provides yaw control for the aircraft, and forward thrust is provided by the fans working in combination. The coaxial rotors are preferably utilized primarily for lift, and not for forward thrust, which simplifies the control requirements. The coaxial rotor with ducted fan configuration also results in lower vibratory loads being imposed on the helicopter, thereby increasing its speed capability. The fan ducts serve to protect the fans, augment the fan thrust at low airspeeds, increase the efficiency of the fans at cruise speeds, and provide horizontal and vertical stabilizing surfaces to ensure aircraft flight stability.