Drone Propeller Noise Reduction Methods

Aerodynamic rotors for air-moving devices with reduced noise levels, comprising a single-part bladed disk with a homogenous, monolithic construction. The rotors achieve low acoustic power as a fraction of input power, enabling quiet operation while maintaining airflow and thrust performance. Design parameters include specific ranges for blade quantity, tip chord, hub-to-tip ratio, and blade incidence angle.

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A novel aviation propeller with thick airfoil blades at constant pitch angles arranged at varying circumferential angles, providing high thrust and reduced acoustic signatures comparable to toroidal propellers, and scalable from small drones to large hovercraft.

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Reducing the noise generated by a propulsion unit of an aircraft like a hybrid or electric aircraft. The propulsion unit has a multi-stage fan with two rotors driven by a motor. The position of the rotors is determined based on the motor signature. The rotor positions are then adjusted to actively cancel the noise produced by the rotors. This is done by changing parameters like phase and speed to mitigate the combined noise from both rotors.

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Ducted fan device for VTOL aircraft with improved thrust and noise reduction. The device features a cylindrical larger duct and multiple smaller ducts surrounding fans, with the smaller ducts positioned outside the larger duct on the upstream side. The smaller ducts are arranged at equal angular intervals and have a specific length-to-diameter ratio to optimize airflow and prevent Coanda effect interference. This configuration controls air separation at the larger duct's lip portion, enhancing thrust and quietness during transition modes and crosswind conditions.

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A propeller blade for an unmanned aerial vehicle (UAV) that reduces tip vortex disturbance between adjacent blades. The blade features a downward-angled tip with a swept angle, where the chord length and installation angle decrease gradually from the blade body to the tip. This design enables the blade tip to deflect high-pressure airflow away from the adjacent blade, minimizing vortex interaction and improving propeller efficiency.

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Aircraft and drone noise reduction system that targets the open tips of propeller blades, a previously underaddressed source of acoustic noise. The system employs a novel shroud design that significantly reduces vortex noise, rotational noise due to thickness, and thrust noise, providing a comprehensive solution to propeller noise reduction.

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A fan with noise reduction features that maintains airflow while minimizing noise. The fan includes a body section with a casing and propellers, and at least one damping element with bristles that can be serrations or velvet-like structures. The bristles can be attached to the propeller edges or surfaces, and can be made of flexible materials like silicone. The damping element can be integral to the body section or attached as a separate component.

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A low-noise thrust generating device for unmanned aerial vehicles (UAVs) that achieves comparable thrust to conventional propeller-driven UAVs while significantly reducing noise levels. The device employs an air duct with a narrow injection port and a chevron-shaped nozzle to generate thrust through a combination of reaction force and static pressure difference. The air duct is designed with a unique shape and internal geometry that enhances thrust performance and reduces noise generation. The device is integrated into a UAV body and can be arranged in multiple radial directions to provide stable and efficient flight.

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A propeller for aircraft with a unique blade design that maximizes thrust and efficiency while minimizing noise. The blade features a maximum chord length at the tip, a thin profile, and a high cambered surface. The pitch-to-diameter ratio is approximately 1:1, allowing for smooth transition of blade tip vortices into the axial direction. This design enables increased thrust, improved efficiency, and reduced noise compared to conventional propellers.

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Shroud design for air moving devices like fans and drones that reduces noise by using Helmholtz resonators. The shroud surrounds the blades and has an annular cavity and opening facing the blades. A Helmholtz resonator is defined by this cavity and opening. As the blades rotate, the resonator reflects and cancels out some of the generated noise, reducing overall noise emission from the air moving device.

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A personal aircraft with vertical takeoff and landing capability, featuring multiple independently controlled rotors for redundant lift and control. The rotors are oriented in fixed, non-planar positions to provide lateral and longitudinal control without attitude changes, and are optimized for low-speed and high-speed flight conditions. The aircraft design enables safe, quiet, and efficient operation, with features such as low-tip-speed rotors, ducted rotors, and foldable wings.

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A noise-reducing and efficiency increasing propeller blade design for drones and other applications. The blade has a pattern of serrations covering the entire surface, as well as serrations on the leading and trailing edges. The serrations on the surface are angled relative to the blade axis when viewed from the side. The serration pattern reduces noise by keeping the flow attached and preventing separation. The angled surface serrations also improve efficiency. The edge serrations further reduce noise by reducing flow separation. The combined serration pattern provides both noise reduction and efficiency improvement compared to plain blades.

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Autonomous aerial vehicle technology featuring a rotor blade attachment system that enables secure, tool-free, and vibration-resistant mounting of propellers to a motor shaft. The system employs a bayonet-style locking mechanism that maintains blade position under various flight conditions, including pusher configurations and three-dimensional flight. The design eliminates the need for separate propeller nuts and addresses issues with nut loosening and loss.

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An airfoil profile for reducing noise in aircraft, comprising a leading edge portion and a trailing edge portion spaced apart along a chordwise direction, an airfoil centroid, and upper and lower airfoil surfaces shaped such that the pressure center of the lifting force is positioned at or behind the airfoil centroid along the chordwise direction. The airfoil surfaces are configured to generate a pitch-down momentum that urges the leading edge portion towards a lower angle of attack, thereby reducing noise generation through vortex shedding and separation.

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VTOL aircraft thrust generation system with improved efficiency and reduced noise compared to conventional propeller systems. The system uses a ducted propeller design with a cylinder, hub, and stators around the propeller blades. This duct covers the propeller periphery. The hub and stators are positioned rearward of the propeller. The duct reduces airflow turbulence and noise compared to an exposed propeller. It also improves thrust efficiency by capturing more airflow and reducing losses. The duct can be attached to the rear wing or center of the aircraft. Multiple ducted propeller units can be lined up for thrust vectoring.

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An air mobility device that increases flying range through Coandă effect enhancement and reduces noise through distributed propulsion. The device features a main body with compression motors, rotatable wings with open spaces, and blowers that utilize compressed air to generate additional propulsion. The wing design incorporates asymmetric streamlined shapes to optimize airflow and enhance the Coandă effect, while the distributed propulsion system minimizes noise generation.

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Electrically driven ducted fan engine for aircraft that reduces noise without adding significant weight or aerodynamic drag compared to using acoustic liners on the entire engine housing. The engine has a rotor inside a duct with fixed guide vanes downstream. The guide vanes have acoustic liners to reduce noise. This focuses noise reduction efforts where it matters most, avoiding the issues of using liners on the whole housing. The liners can be Helmholtz-type with cavities covered by perforated plates to absorb sound energy.

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A noiseless flight propellant system that eliminates propeller noise through a novel air-blowing mechanism. The system comprises a rotating disk assembly with open-air core disks that draw in air and expel it in a centrifugal flow pattern, and a hemispherical air collector that channels the expelled air in a predetermined direction. The system also includes an inverted cone-shaped air converger and a steering wing for flight control.

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A low-noise engine for aerospace vehicles that reduces vibration and noise during high-speed operation. The engine features a spiral shaft with a noise reduction device comprising a rotating rod, low-pressure gas machine, heat sink, and shock-absorbing elements. The device is designed to mitigate vibrations and noise through a combination of mechanical and elastic structures, including springs, damping rods, and shock-absorbing plates.

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An unmanned aerial vehicle (UAV) with vertical takeoff and landing (VTOL) capability that generates low noise levels. The UAV uses an ion thruster with asymmetrical electrodes subjected to a potential differential to produce vertical thrust, and a vector thrusting device to control roll, pitch, and yaw. The ion thruster electrodes are integrated into the primary structure of the craft, eliminating the need for separate engines or wings. A thrust vectoring system with pivoting fans enables controlled flight in any direction while maintaining low noise levels.

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