Abstract: A fan apparatus is disclosed, including a duct having an inlet opening, a fan mounted in the duct, and a plurality of louver devices positioned at the inlet opening. Each louver device has an open position and a closed position, and adjacent louver devices define a plurality of airflow channels. Each airflow channel has a curvature profile that changes as the louver devices move between open and closed positions.

Abstract: Winged tilt-rotor vertical take-off and landing (VTOL) aircraft and related methods are disclosed. Aircraft comprise an airframe comprising one or more wings; one or more tilt-adjustable rotors positioned forward of the one or more wings; and one or more fixed-tilt rotors positioned behind at least one of the one or more wings. Methods comprise tilting only one or more forward rotors positioned in front of one or more wings of the aircraft, and not tilting one or more rearward rotors positioned behind at least one of the one or more wings.

Abstract: Rotor assemblies for aircraft are described where one or more blades of the rotor assembly includes a blade alignment device that passively orients a blade in response to an airflow around the blade alignment device when the rotor assembly is free-wheeling. One embodiment comprises a method of operating a rotor assembly for aircraft. The method comprises operating the rotor assembly in a free-wheeling state, where the rotor assembly includes a rotary hub that rotates about an axis and a plurality of blades extending radially from the rotary hub. At least one of the plurality of blades includes a blade alignment device. The method further comprises aligning the at least one of the plurality of blades in response to airflow around the blade alignment device when the rotor assembly is in the free-wheeling state.

Abstract: A fan apparatus is disclosed, including a duct having an inlet opening, a fan mounted in the duct, and a plurality of louver devices positioned at the inlet opening. Each louver device has an open position and a closed position, and adjacent louver devices define a plurality of airflow channels. Each airflow channel has a curvature profile that changes as the louver devices move between open and closed positions.

Abstract: Winged tilt-rotor vertical take-off and landing (VTOL) aircraft and related methods are disclosed. Aircraft comprise an airframe comprising one or more wings; one or more tilt-adjustable rotors positioned forward of the one or more wings; and one or more fixed-tilt rotors positioned behind at least one of the one or more wings. Methods comprise tilting only one or more forward rotors positioned in front of one or more wings of the aircraft, and not tilting one or more rearward rotors positioned behind at least one of the one or more wings.

Abstract: Rotor assemblies for aircraft are described where one or more blades of the rotor assembly includes a blade alignment device that passively orients a blade in response to an airflow around the blade alignment device when the rotor assembly is free-wheeling. One embodiment comprises a method of operating a rotor assembly for aircraft. The method comprises operating the rotor assembly in a free-wheeling state, where the rotor assembly includes a rotary hub that rotates about an axis and a plurality of blades extending radially from the rotary hub. At least one of the plurality of blades includes a blade alignment device. The method further comprises aligning the at least one of the plurality of blades in response to airflow around the blade alignment device when the rotor assembly is in the free-wheeling state.