Abstract: An unmanned aerial vehicle (UAV) includes a fuselage, a pair of fixed wings attached to the fuselage, a tail assembly attached to an aft portion of the fuselage and including a pair of stabilizers, a plurality of distributed propulsion units having first propellers that rotate about first rotational axes positioned below the fixed wings, and a plurality of tail propulsion units having second propellers that rotate about second rotational axes each positioned inline with one of the stabilizers. The first propellers are mounted fore of the fixed wings and the second propellers are mounted fore of a corresponding one of the stabilizers. Three or more of the distributed propulsion units are mounted to each of the fixed wings.

Abstract: A technique of operating an unmanned aerial vehicle (UAV) adapted for a package delivery mission includes: powering distributed propulsion units during takeoff and landing segments of the package delivery mission and idling at least a portion of the distributed propulsion units while powering a pair of outboard propulsion units during a cruise segment of the package delivery mission. The distributed propulsion units are mounted below fixed wings of the UAV and have first propellers mounted fore of the fixed wings. The outboard propulsion units are each mounted to a corresponding one of the fixed wings outboard of the distributed propulsion units. The outboard propulsion units include outboard propellers having a larger diameter than the first propellers.

Abstract: A propeller blade for an unmanned aerial vehicle (“UAV”) is disclosed. The UAV includes a plurality of lift propellers and at least one thrust propeller. Each of the plurality of thrust propellers includes a thrust propeller blade coupled to a hub of the thrust propeller. The thrust propeller blade is configured such that a centrifugal force acting on the thrust propeller blade causes a thrust propeller disk area to increase from a first disk area when the UAV is in a first operational state to a second disk area when the UAV is in a second operational state.

Abstract: A propeller blade for an unmanned aerial vehicle (“UAV”) is disclosed. The UAV includes a plurality of lift propellers and at least one thrust propeller. Each of the plurality of thrust propellers includes a thrust propeller blade coupled to a hub of the thrust propeller. The thrust propeller blade is configured such that a centrifugal force acting on the thrust propeller blade causes a thrust propeller disk area to increase from a first disk area when the UAV is in a first operational state to a second disk area when the UAV is in a second operational state.

Abstract: An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

Abstract: An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

Abstract: An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

Abstract: A computer implemented method of distributing noise exposures to unmanned aerial vehicles (UAVs) over a neighborhood includes: accessing a noise exposure map stored in a database and generating a new flight path over the neighborhood for a first UAV of the UAVs based at least in part on the noise exposure map. The noise exposure map includes noise exposure values indexed to locations within the neighborhood. Each of the noise exposure values quantifies a cumulative noise exposure of a corresponding one of the locations due at least in part to historical flight paths of the UAVs over the neighborhood.

Abstract: A technique of controlling tonal noises produced by an unmanned aerial vehicle (UAV) includes generating thrust with a plurality of rotor units mounted to the UAV to propel the UAV into flight. Each of the rotor units includes a bladed rotor. A rotation rate or a phase delay of at least one of the rotor units is adjusted relative to another of the rotor units. The adjustment causes a spread in the tonal noises generated by the rotor units.

Abstract: An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

Abstract: An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

Abstract: A computer implemented method of distributing noise exposures to unmanned aerial vehicles (UAVs) over a neighborhood includes: accessing a noise exposure map stored in a database and generating a new flight path over the neighborhood for a first UAV of the UAVs based at least in part on the noise exposure map. The noise exposure map includes noise exposure values indexed to locations within the neighborhood. Each of the noise exposure values quantifies a cumulative noise exposure of a corresponding one of the locations due at least in part to historical flight paths of the UAVs over the neighborhood.

Abstract: A computer implemented method of distributing noise exposures to unmanned aerial vehicles (UAVs) over a neighborhood includes: receiving flight routing requests to fly the UAVs over the neighborhood; accessing a noise exposure map stored in a noise exposure database in response to the flight routing requests; and generating new flight paths for the UAVs over the neighborhood that load level additional noise exposures that the new flight paths will contribute to the noise exposure map. The noise exposure map includes noise exposure values indexed to properties within the neighborhood. The noise exposure values quantify cumulative noise exposures of the properties due to historical flight paths of the UAVs over the neighborhood.

Abstract: A computer implemented method of distributing noise exposures to unmanned aerial vehicles (UAVs) over a neighborhood includes: receiving flight routing requests to fly the UAVs over the neighborhood; accessing a noise exposure map stored in a noise exposure database in response to the flight routing requests; and generating new flight paths for the UAVs over the neighborhood that load level additional noise exposures that the new flight paths will contribute to the noise exposure map. The noise exposure map includes noise exposure values indexed to properties within the neighborhood. The noise exposure values quantify cumulative noise exposures of the properties due to historical flight paths of the UAVs over the neighborhood.

Abstract: A technique of controlling tonal noises produced by an unmanned aerial vehicle (UAV) includes generating thrust with a plurality of rotor units mounted to the UAV to propel the UAV into flight. Each of the rotor units includes a bladed rotor. A rotation rate or a phase delay of at least one of the rotor units is adjusted relative to another of the rotor units. The adjustment causes a spread in the tonal noises generated by the rotor units.

Abstract: An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.