Noise Reduction in Drone Flight

A high-efficiency, low-noise rotor wing design for unmanned aerial vehicles that improves flight efficiency and reduces noise compared to traditional rotor blades. The wing has a unique shape with a sequential connection of a smooth section and a sweepback section. The sweepback section has an anti-paddle tip, a sweep upper arc, and a sweep lower arc that meet at a pointed end. This configuration provides higher lift-drag ratio, better stability, and reduced noise compared to symmetrical blades. The sequential connection allows smooth airflow transition between the sections. The anti-paddle tip prevents stall vortices. The pointed end reduces noise by smoothing airflow separation.

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Noise-reducing propeller for indoor drones to significantly reduce the noise generated by drones when flying indoors. The propeller is designed using the Betz minimum energy loss criterion and blade theory. The blade chord lengths and pitch angles are calculated to minimize energy loss and noise. The chord length distribution is weighted with 0.18 at the tip and 0.46 at the root. This reduces the tip chord length for lower energy loss and less noise conversion. The pitch angles gradually decrease from the root to tip. This noise-reducing propeller can be used on indoor drones to significantly lower their indoor noise levels.

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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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A propeller for an aircraft that reduces noise without sacrificing efficiency compared to conventional unducted fan propellers. The propeller has an upstream row of rotating blades and a fixed downstream row. The blades in the downstream row are positioned in a specific angular region around the propeller axis. This configuration allows the downstream blades to avoid interference with vortices generated by the upstream blades. The blades in the downstream row are truncated to reduce noise, but by positioning them in a way that avoids vortex interactions, the noise reduction is more effective than just blindly truncating them. This reduces noise levels without compromising efficiency compared to untruncated blades.

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Low noise, high efficiency propellers for unmanned aerial vehicles (UAVs) that reduce noise and power requirements compared to conventional propellers. The propellers have blades with tapered angles near the tips that decrease below zero lift. This unloaded region reduces vortex formation and induced drag, lowering noise and power. The propellers also have shorter overall length than conventional propellers to further reduce noise. The propellers maintain high efficiency without needing higher rotational speeds to compensate for reduced lift.

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Thrust generating device for VTOL aircraft that reduces noise compared to conventional propeller ducts. The device has a duct with stators surrounding the propeller, but unlike conventional ducts that have stators in front of the propeller, the stators are placed behind the propeller. This avoids obstructing the airflow into the propeller and disrupting the propeller's airflow, which creates noise. The stators are located aft of the propeller to still provide thrust and improve efficiency.

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Aerial vehicles like drones with rotor units having asymmetric blade shapes to reduce perceived noise compared to symmetric blades. The asymmetric blades are designed such that their vortex interactions cause the rotor unit to emit a broader spectrum of softer frequencies instead of just strong fundamentals. This makes the overall sound output less objectionable to humans. The asymmetry is selected based on blade area relationships to achieve this acoustic behavior.

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Propeller design for rotorcraft that improves aerodynamic efficiency and reduces noise compared to conventional propellers. The propeller has blades with specific twist angles at three radial locations: 36°, 59.5°, and 83.3% of the radius. This twist distribution reduces power consumption for the same lift and allows lower rotational speeds. The swept-back blade tip further reduces tip vortex turbulence and noise.

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Propeller blade design for unmanned aerial vehicles that reduces noise and improves efficiency compared to conventional propellers. The propeller blade is a swept shape with torsion angles between the wing sections. This creates a more aerodynamic and tensioned blade profile that reduces noise compared to straight blades. The swept blade shape also improves lift and thrust at lower speeds, making it suitable for unmanned aerial vehicles.

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Aircraft with reduced noise characteristics by using different propeller designs on the same vehicle to distribute energy over a wider spectrum and reduce perceived noise annoyance. The aircraft has multiple electric motors driving propellers with distinct blade geometries that deliver equal thrust at a predetermined RPM. This avoids constructive interference of tonal noise from multiple propellers spinning at the same RPM. Dynamic RPM monitoring and adjustment compensates for deviations.

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Blade design for unmanned aerial vehicles (UAVs) propellers that reduces vortex interference between blades and improves stability. The blade has a dihedral-angled tip that offsets vortex formation downwards. The chord length and installation angle of the blade sections gradually decrease towards the tip. This offsets vortex tracks away from following blades, reducing disturbance and flapping.

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Reducing noise from unmanned aerial vehicle propellers to improve safety and stealthiness. The propeller blades have a special sound absorbing coating applied using a spray welding process. The coating is made by mixing sound absorbing materials like cellulose fibers and melamine resin, and applying it to the blade surfaces using a thermal spray welding process. This coating absorbs and dissipates sound energy instead of reflecting it, reducing the overall noise produced by the propellers.

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A propeller design for unmanned aerial vehicles (UAVs) that reduces high-frequency noise generated by the propeller. The propeller has screw-shaped blades with a helical twist that decreases as you move towards the tip. This twist profile reduces blade tip vortices, which are a major source of high-frequency noise. The screw-shaped blades also have a curved cross-section that further reduces noise by smoothing the airflow over the blade surface.

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A noise-reducing propeller design for unmanned aerial vehicles (UAVs) that reduces noise in both low-altitude and high-altitude environments. The propeller optimizes its shape to improve aerodynamic efficiency and avoid noise peaks. The blade tips are rounded and the trailing edges are serrated. This distribution of loads along the blade span improves efficiency compared to sharp tips and straight edges. The propeller diameter is also optimized to avoid resonance. The goal is to balance noise reduction with power requirements by iteratively optimizing the propeller shape and diameter for both low and high altitudes.

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A noise-reducing blade design for unmanned aerial vehicles (UAVs) to reduce the loudness of rotor blades. The blade has features like protrusions to cut and break up large vortices into smaller ones, zigzag concave sections to prevent tip stall noise, and a distorted 8-shape to reduce impact with objects. The blade shape, protrusions, and concave sections are designed to reduce aerodynamic noise compared to conventional UAV blades.

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Propeller design that reduces noise and vibration compared to conventional straight blades. The propeller has curved wingtip sections that transition smoothly to the blade root. The curved sections have camber and twist to prevent vortex formation at the tips. The propeller can also have blades that are removably attached to the hub for easier manufacturing and replacement. The hub can be integral with the blades or detachable.

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A high-efficiency, low-noise, high-load, and high-safety factor unmanned aerial vehicle (UAV) lifting hook for industrial applications like construction and rescue. The UAV has a unique four-propeller design where the sum of the blade areas exceeds the circular area formed by rotation. This provides better lift efficiency, reduced vibration, and lower noise compared to conventional UAVs. The UAV also has a detachable lifting hook for carrying cargo. The UAV uses a battery, motor, and flight control system like a conventional UAV but with larger blade areas. This allows heavier loads and better lifting performance. The UAV can also tilt and turn like a helicopter for maneuverability.

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Bionic noise-reducing unmanned aerial vehicle (UAV) propeller design that reduces the noise generated by UAV propellers. The propeller has a blade shape inspired by bird wings to create smoother airflow transition and reduce noise. The blade has a leading edge with an outer segment that extends outwards along a spiral tangent line and forms a bird-like wing shape. This wing limit portion allows air to flow smoothly from the blade tip instead of creating turbulent separation. The blade also has a thinned section near the tip to further reduce noise. The propeller can be arranged in a split blade configuration with matching front and rear blades connected to the UAV body using double-layer fasteners.

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Ducted propeller for unmanned aerial vehicles (UAVs) that improves efficiency compared to open propellers. The ducted propeller has a ducted body with a cavity containing the propeller. The inner wall of the duct has clearance grooves matching the blade outer edge path. The blade rotates into the grooves during operation. This reduces tip clearance compared to unducted propellers. The clearance grooves allow the blade to fully fill the duct volume for higher efficiency. The grooves simplify design compared to adhesive tapes used in prior art ducted propellers.

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Rotor mechanism for unmanned aerial vehicles that reduces noise and prevents motor damage if the propeller blades stop rotating. The mechanism has a rotating inner ring that connects to the propeller shaft. If the propeller blades stop, the ring continues rotating relative to the fixed outer shell. A sliding block separates the ring from the shaft, allowing the motor to idle instead of overloading if the propellers stop. This prevents motor damage and reduces noise compared to sudden stops. The inner ring rotation also changes horizontal airflow into vertical to reduce noise.

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