A method of mounting a metal blade root to a composite propeller blade body includes inserting a connection portion of the blade body into a bore formed in the blade root, wherein the connection portion comprises at least one depression formed in an outer surface thereof, and applying pressure to the outer surface of the blade root to cause it to deform and engage with the depressions, thereby mechanically coupling the blade root to the propeller blade body.

A propeller system combines innovative strategies to create a new methodology to reduce propeller or rotor noise. The propeller is specifically aimed for ultra-quiet electrically powered aircraft for use in high proximity aviation, but its low-noise advantages will extend to other purposes. The propeller blade includes geometries, along with size and operational limitations that minimize rotational and vortex noise, vibration and span-wise air flow on the blade. To further reduce noise, the propeller provides greater relative thrust on the inboard portions of the blade than do conventional propellers and provides less than conventional relative thrust including negative thrust at the outermost portions of the blade. The propeller blade includes stepped changes in local blade stiffness at calculated intervals that can reduce resonant blade vibrations and their resultant noise. This ultra-quiet propeller design can also be used for quieting hovercraft, drones, surveillance aircraft, indoor fans, wind tunnels and other applications.

A propulsion engine for an aeronautical vehicle defines a radial direction and a cooling air flowpath. The propulsion engine includes a power source; and a fan including a fan blade rotatable by the power source and extending generally along the radial direction, the fan blade defining an inlet, an outlet, and a cooling air passage extending between the inlet and the outlet and in airflow communication with the cooling air flowpath, the inlet being positioned inward from the outlet along the radial direction to provide a cooling airflow through the cooling air flowpath.

A propulsion engine for an aeronautical vehicle defines a radial direction and a cooling air flowpath. The propulsion engine includes a power source; and a fan including a fan blade rotatable by the power source and extending generally along the radial direction, the fan blade defining an inlet, an outlet, and a cooling air passage extending between the inlet and the outlet and in airflow communication with the cooling air flowpath, the inlet being positioned inward from the outlet along the radial direction to provide a cooling airflow through the cooling air flowpath.

A fan is disclosed. The fan includes a base mountable to a ceiling; a base motor contained in the base; a multi-section shaft operably connected to the base motor and moveable between a collapsed position and an extended position; and a fan assembly connected to the multi-section shaft and including a fan motor and at least one fan blade operably connected to the fan motor, wherein in response to a signal, the base motor raises or lowers the fan assembly by moving the multi-section shaft between the collapsed position and the extended position.

A fan is disclosed. The fan includes a base mountable to a ceiling; a base motor contained in the base; a multi-section shaft operably connected to the base motor and moveable between a collapsed position and an extended position; and a fan assembly connected to the multi-section shaft and including a fan motor and at least one fan blade operably connected to the fan motor, wherein in response to a signal, the base motor raises or lowers the fan assembly by moving the multi-section shaft between the collapsed position and the extended position.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.

The present invention provides a power device generating greater propelling force and finds that traditional power devices do not include all propelling forces based on the fundamental core propelling force source problem. External pressure is guided to the traditional power devices since the inner speed is higher the outer speed, power consumption for overcoming fluid resistance is high, and mutual contradiction results are obtained. The unique difference between the present invention and general common sense lies in opposite fluid pressure directions; inner fluid channels and outer fluid channels with higher flow speeds are formed to generate pressure differences which guides the fluid pressure to the outside and serve as propelling force, thus the present invention creatively finds three propelling force sources, two lifting force or propelling force sources of helicopters or airplanes driven by propellers and two propelling force sources for sufficient burning of fuel in combustion chambers of engines.

In one embodiment, an assembly fixture may include a base structure including a plurality of strands of a fiber-reinforced thermoplastic material comprising a thermoplastic embedded with a plurality of reinforcement fibers, wherein the plurality of reinforcement fibers is aligned within each strand of the plurality of strands, and wherein the base structure further comprises an anisotropic thermal expansion property based on an orientation of the plurality of reinforcement fibers within the base structure, The assembly fixture may further include a plurality of fastening structures coupled to the base structure, wherein the plurality of fastening structures is configured to fasten a plurality of components of a composite structure for assembly using a heated bonding process.

In one embodiment, an assembly fixture may include a base structure including a plurality of strands of a fiber-reinforced thermoplastic material comprising a thermoplastic embedded with a plurality of reinforcement fibers, wherein the plurality of reinforcement fibers is aligned within each strand of the plurality of strands, and wherein the base structure further comprises an anisotropic thermal expansion property based on an orientation of the plurality of reinforcement fibers within the base structure, The assembly fixture may further include a plurality of fastening structures coupled to the base structure, wherein the plurality of fastening structures is configured to fasten a plurality of components of a composite structure for assembly using a heated bonding process.