An air vehicle configured to augment effective drag to change the rate of descent of the air vehicle in flight via propeller shaft rotation direction reversal, i.e., thrust reversal.

An air vehicle configured to augment effective drag to change the rate of descent of the air vehicle in flight via propeller shaft rotation direction reversal, i.e., thrust reversal.

An air vehicle configured to augment effective drag to change the rate of descent of the air vehicle in flight via propeller shaft rotation direction reversal, i.e., thrust reversal.

An air vehicle configured to augment effective drag to change the rate of descent of the air vehicle in flight via propeller shaft rotation direction reversal, i.e., thrust reversal.

Provided herein is a rotor attachment assembly for an aircraft. A rotor attachment assembly includes a connecting assembly associated with the aircraft and a rotor assembly configured to be connected to the connecting assembly. The rotor assembly includes a plurality of fins configured to fit a respective plurality of cut-outs of the connecting assembly, a hollow section configured to accommodate at least a part of a pin of the connecting assembly so as to center the rotor assembly relative to the connecting assembly, and a spring configured to expand to allow the fins to pass and to close to retain the fins when the rotor assembly is connected to the connecting assembly.

Provided herein is a rotor attachment assembly for an aircraft. A rotor attachment assembly includes a connecting assembly associated with the aircraft and a rotor assembly configured to be connected to the connecting assembly. The rotor assembly includes a plurality of fins configured to fit a respective plurality of cut-outs of the connecting assembly, a hollow section configured to accommodate at least a part of a pin of the connecting assembly so as to center the rotor assembly relative to the connecting assembly, and a spring configured to expand to allow the fins to pass and to close to retain the fins when the rotor assembly is connected to the connecting assembly.

A technique for controlling vertical propulsion units of an aerial vehicle includes determining whether an initial thrust command output vector results in a thrust command clipping of one of the vertical propulsion units. The vertical propulsion units are physically organized into propulsion rings including an inner ring and an outer ring. Torque associated with the initial thrust command output vector is transferred from each the vertical propulsion units in the outer ring to the vertical propulsion units in the inner ring when the thrust command clipping of one of the vertical propulsion units in the outer ring occurs. A revised thrust command output vector is determined after transferring the torque. The vertical propulsion units are driven according to the revised thrust command output vector.

An aerial vehicle includes an airframe; vertical propulsion units, and a controller. The vertical propulsion units are mounted to the airframe and include propellers oriented to provide vertical propulsion to the aerial vehicle. The vertical propulsion units are physically organized in quadrants on the airframe with each of the quadrants including two or more of the vertical propulsion units. The controller is coupled to the vertical propulsion units to control operation of the vertical propulsion units. At least two of the vertical propulsion units in each of the quadrants are adapted to counter-rotate from each other during flight of the aerial vehicle.

A technique for controlling vertical propulsion units of an aerial vehicle includes determining whether an initial thrust command output vector results in a thrust command clipping of one of the vertical propulsion units. The vertical propulsion units are physically organized into propulsion rings including an inner ring and an outer ring. Torque associated with the initial thrust command output vector is transferred from each the vertical propulsion units in the outer ring to the vertical propulsion units in the inner ring when the thrust command clipping of one of the vertical propulsion units in the outer ring occurs. A revised thrust command output vector is determined after transferring the torque. The vertical propulsion units are driven according to the revised thrust command output vector.

A propeller system combines innovative strategies to create a new methodology to reduce propeller or rotor noise. The propeller is specifically aimed for ultra-quiet electrically powered aircraft for use in high proximity aviation, but its low-noise advantages will extend to other purposes. The propeller blade includes geometries, along with size and operational limitations that minimize rotational and vortex noise, vibration and span-wise air flow on the blade. To further reduce noise, the propeller provides greater relative thrust on the inboard portions of the blade than do conventional propellers and provides less than conventional relative thrust including negative thrust at the outermost portions of the blade. The propeller blade includes stepped changes in shape at calculated intervals that can reduce resonant blade vibrations and their resultant noise. This ultra-quiet propeller design can also be used for quieting hovercraft, drones, surveillance aircraft, indoor fans, wind tunnels and other applications.