Abstract: A torque and pitch managed four rotor aircraft includes intersecting blades connected by synchronizing gears. The power for the rotors is provided by individual motors, one for each rotor, the motors preferably electric. Each rotor-motor assembly includes a torque management system including a set of torque sensors mounted on the drive shaft of the rotor-motor, the torque management system configured to balance the load torque presented by the rotors against the torque supplied by the motors. An additional overriding feedback system regulates rotational speed of the rotors. Direction of the aircraft is effected by adjusting the pitch of the individual rotors, and power is supplied through a battery and/or a motor-generator system located in the aircraft.

Abstract: A torque and pitch managed four rotor aircraft, having intersecting blades connected by synchronizing gears. The power for the rotors is provided by individual motors, one for each rotor, preferably electric. Each rotor-motor assembly includes a torque managing means comprising two torque sensors, one measuring the load torque presented by the rotors and one measuring the drive torque supplied by the motors. A feedback or servo system for each rotor causes the motors to supply a drive torque that is equal to the load torque for each rotor. A second, overriding feedback system regulates the rotors rotational speed. Speed and direction of the aircraft is effected by adjusting the fixed pitch of the individual rotors. Power is supplied through a battery and motor/generator system located elsewhere in the aircraft.

Abstract: The present invention provides a feedback-controlled audio system. A single internal pressure-sensitive detector is used as the sensor. The primary radiator is mounted facing inward to minimize acoustical delay from the speaker. The present invention also provides a method for increasing acoustical accuracy using such an audio system.