Abstract: Systems and methods to actively control vibrations affecting an aerial vehicle are described. Vibrations affecting a location of interest on an aerial vehicle may be measured, and phases of one or more propellers of the aerial vehicle may be determined. Based on the measured vibrations and determined phases of propellers, adjustments to the phases of the propellers may be determined to modify the vibrations affecting the location of interest. In this manner, vibrations at a location of interest on an aerial vehicle may be reduced, minimized, increased, induced, or otherwise modified as desired.

Abstract: An aerial vehicle may include adjustable shrouds to selectively provide protection for propellers of the aerial vehicle. The adjustable shrouds may be moved to an extended configuration around a periphery of one or more propellers during generally vertical flight or hovering operations, when delivery a payload, and/or upon detecting objects in proximity. Likewise, the adjustable shrouds may be moved to a retracted configuration that eliminates or minimizes adverse aerodynamic effects during generally horizontal flight operations, when operating at high altitude, and/or upon detecting no objects in proximity. The adjustable shrouds may include various designs, such as fan shrouds, telescoping shrouds, folding shrouds, and deployable arm shrouds.

Abstract: Various mechanisms for adjusting pitches of propeller blades are described. For example, the pitch adjustment mechanism may include a propeller hub enclosing a geared mechanism that cooperates with a compound gearbox having first and second planetary stages to adjust pitches of propeller blades. Alternatively, the pitch adjustment mechanism may include a propeller hub enclosing a pitch adjustment assembly that utilizes tension cables and torsion springs, or rack-and-pinion structures, to adjust pitches of propeller blades. Using any of the various mechanisms, the pitches of propeller blades may be rotated at least 90 degrees, and up to and exceeding 360 degrees, in order to effect thrust reversals and/or adjust thrust profiles.

Abstract: Flow conditions affecting an aerial vehicle may be determined using one or more auxiliary aerial vehicles, which may be outfitted with one or more airspeed sensors and other systems for modeling air flow within a vicinity of the aerial vehicle. With the auxiliary aerial vehicles operating in selected positions or formations with respect to the aerial vehicle, the aerial vehicle may perform one or more testing evolutions requiring the operation of any propulsion motors, control surfaces or other systems. Flow conditions during the testing evolutions may be modeled based on data captured by sensors aboard the auxiliary aerial vehicles, and the modeled flow conditions may be used to determine whether the testing evolutions were successfully completed by the aerial vehicle.

Abstract: Aerial vehicles may be equipped with propellers having pivotable blades that are configured to rotate when the propellers are not rotating under power. A pivotable blade may rotate about an axis of a propeller with respect to a hub until the pivotable blade is coaligned with a fixed blade. When the propeller is rotating, a lifting force from the blade may cause the blade to rotate to a deployed position that is not coaligned with the fixed blade.

Abstract: An aerial vehicle having a single wing is configured for vertical-flight and forward-flight operations. The wing has a substantially high aspect ratio. The aerial vehicle includes tilt motor assemblies disposed at a forward end and an aft end of a fuselage. The tilt motor assemblies are configured to orient motors and rotors vertically, horizontally, or at any angle between vertical and horizontal. A pair of parallel booms are mounted beneath the wing on either side of the fuselage. Each of the booms has at least one vertically oriented motor and rotor associated therewith, and a vertical fin extending thereunder. Additionally, a forward tilt motor assembly includes a rotatable extension that is deployed when the motor assembly is configured for vertical flight, enabling the aerial vehicle to land on the vertical fins and the landing rotatable extension.

Abstract: An aerial vehicle may include adjustable configurations to selectively provide protection for propellers of the aerial vehicle. Portions of the wing and/or the tail plane of the aerial vehicle may be reconfigured to an extended configuration around a periphery of one or more propellers during generally vertical flight or hovering operations, when delivery a payload, and/or upon detecting objects in proximity. Likewise, the portions of the wing and/or the tail plane may be reconfigured to a retracted configuration that eliminates or minimizes adverse aerodynamic effects during generally horizontal flight operations, when operating at high altitude, and/or upon detecting no objects in proximity. During the reconfiguration, portions of the leading edge of the wing may be extended or retracted, and/or portions of the tail plane may be extended, retracted, and/or rotated.

Abstract: Various mechanisms for adjusting pitches of propeller blades are described. For example, the pitch adjustment mechanism may include a propeller hub enclosing a geared mechanism that cooperates with a compound gearbox having first and second planetary stages to adjust pitches of propeller blades. Alternatively, the pitch adjustment mechanism may include a propeller hub enclosing a pitch adjustment assembly that utilizes tension cables and torsion springs, or rack-and-pinion structures, to adjust pitches of propeller blades. Using any of the various mechanisms, the pitches of propeller blades may be rotated at least 90 degrees, and up to and exceeding 360 degrees, in order to effect thrust reversals and/or adjust thrust profiles.

Abstract: Aerial vehicles may be equipped with propellers having pivotable blades that are configured to rotate when the propellers are not rotating under power. A pivotable blade may rotate about an axis of a propeller with respect to a hub until the pivotable blade is coaligned with a fixed blade. When the propeller is rotating a lifting force from the blade may cause the blade to rotate to a deployed position that is not coaligned with the fixed blade.

Abstract: An aerial vehicle having a single wing is configured for vertical-flight and forward-flight operations. The wing has a substantially high aspect ratio. The aerial vehicle includes tilt motor assemblies disposed at a forward end and an aft end of a fuselage. The tilt motor assemblies are configured to orient motors and rotors vertically, horizontally, or at any angle between vertical and horizontal. A pair of parallel booms are mounted beneath the wing on either side of the fuselage. Each of the booms has at least one vertically oriented motor and rotor associated therewith, and a vertical fin extending thereunder. Additionally, a forward tilt motor assembly includes a rotatable extension that is deployed when the motor assembly is configured for vertical flight, enabling the aerial vehicle to land on the vertical fins and the landing rotatable extension.