A commanded control signal is compared against an adaptive control signal in order to detect a rotor strike by a rotor included in an aircraft, wherein the adaptive control signal is associated with controlling the rotor and the adaptive control signal varies based at least in part on the commanded control signal and state information associated with the rotor. In response to detecting the rotor strike, a control signal to the rotor is adjusted in order to reduce a striking force associated with the rotor.

Various embodiments include methods, devices, and aerial robotic vehicles for adjusting a proximity threshold implemented in a collision avoidance system based on whether propeller guards are installed. Methods may include an aerial robotic vehicle processor determining whether a propeller guard is installed, setting, a proximity threshold for collision avoidance based on the determination as to whether propeller guard(s) is/are installed on the aerial robotic vehicle, and controlling one or more motors of the aerial robotic vehicle using the proximity threshold for collision avoidance. When propeller guards are installed, the proximity threshold may be set at a smaller distance than when propeller guards are not installed. The determination of whether a propeller guard is installed may be based on sensor data from one or more sensors configured to detect or indicate the presence of a propeller guard, and/or based on rotor revolution rates determined from a motor or motor controller.

Embodiments are directed to a drive shaft apparatus comprising a first rotary member and a second rotary member arranged coaxially with said first rotary member. The rotary members are fixedly connected at a first end so that they rotate together. Each rotary member has a set of elements spaced apart around its circumference at a second end. The elements on the first rotary member are spaced apart from the elements on the second rotary member at rest. The first rotary member undergoes torsion when a load is applied during rotation, which causes the first rotary member elements to move closer to the second rotary member elements. The first elements engage the second elements when a torque load less than a yield torque is applied to the first rotary member, which transfers at least a portion of the torque load to the second rotary member.

Methods and systems are configured to store user data and control access to the user data, wherein the data is stored remotely from the user (such as external to a user's computing device) and the user's data is maintained anonymously. Content is stored in association with a user identifier and access by third parties is controlled by linked third party identifiers.

Disclosed is a drone rotor cage. The drone rotor cage may include a motor housing, a plurality of spars, and a plurality of ribs. The plurality of spars may extend from the motor housing. Each of the plurality of spars may have a spar height and a spar thickness. The spar height may be greater than the spar thickness. Each of the ribs may extend from a respective one of the plurality of spars. Each of the plurality of ribs may have a rib height and a rib thickness. The rib height may be greater than the rib thickness. The plurality of spars and the plurality of ribs may define a space sized to allow a rotor to spin freely when the rotor cage is attached to a drone.

A rotorcraft including a main rotor, flight controls connected to the main rotor the main rotor, a plurality of engines connected to the main rotor and operable to drive the main rotor, a main rotor revolutions per minute (RPM) sensor, and a monitoring system operable to determine an engine failure of the plurality of engines. The monitoring system is further operable to engage an automated autorotation entry assist process in response to at least determining the engine failure and according to the measured main rotor RPM, where the automated autorotation entry assist process comprises the monitoring system generating one or more rotor RPM related commands according to at least a target main rotor RPM and the measured main rotor RPM, where the automated autorotation entry assist process further comprises controlling the one or more flight controls according to the one or more rotor RPM related commands.

Systems and methods for operating an engine in a multi-engine rotorcraft are described herein. A first parameter indicative of torque of a first engine is obtained. A decrease of the first parameter is detected. In response to detecting the decrease of the first parameter, an autorotation of the rotorcraft is accommodated, A second parameter indicative of torque of a second engine of the rotorcraft is assessed while accommodating the autorotation. If the second parameter has not decreased, a shaft shear of the first engine is identified and accommodating of the autorotation is ended. If the second parameter has decreased, the accommodating is maintained.

A battery powered helicopter uses one or more torque arms as the power source directly driving the main rotor blades, causing them to rotate. The helicopter does not require a combustion engine, a clutch, a reducer, a tail driver, a tail boom, a tail rotor, or a fuel supply system. The output shaft of the high-energy motor is coaxial with the main rotor shaft. The centrifugal force of one or more motor(s) is negligible or minimized. The torque arm assembly includes a plurality of torque arms. Each of the torque arms of the plurality of torque arms includes a propeller and a driving system.

A locking device for use in a rotor blade, said locking device comprising: a locking member that is arranged to be movable from an unlocked position to a locking position upon experiencing sufficiently fast rotation; and a selectively engagable retaining device arranged when engaged to retain the locking member in the unlocked position. The locking device will typically default to an unlocked position during normal rotation and will only be locked so as to prevent movement when the retaining device is de-activated. A method of locking an actuator is also disclosed. The locking device has applications in helicopter rotor blades and wind turbine blades amongst others.

An unmanned aerial vehicle comprising a rotor having one or more propeller blades and a propeller guard surrounding the rotor. The propeller guard comprises a main guard surrounding the one or more propeller blades and a movable guard vertically displaced from the main guard. The movable guard is movable from a default position to an engaged position by temporarily deforming the movable guard such that the movable guard contacts and obstructs rotation of the one or more propeller blades.