Abstract: An ultrasonic air data system can include a pole having a length longer than a boundary layer thickness of a boundary layer flow such that at least a distal end of the pole is configured to extend outwardly from an aircraft surface to be at least partially outside of the boundary layer flow. The system can include a transmitter disposed on or in the pole at or near the distal end of the pole such that the transmitter is located at least partially outside of the boundary layer flow when in use, wherein the transmitter is configured to output a transmitter signal. The system can include one or more receivers disposed downstream of the pole as defined by the boundary layer flow and configured to receive the transmitter signal.

Abstract: A wave generator for an ultrasonic air data system can be configured to collect data derived from a flow of air in a downstream direction. The wave generator can include an ultrasonic wave source configured to output ultrasonic waves from a first end and a wave shaper connected to the first end of the ultrasonic wave source. The wave shaper can be configured to focus the ultrasonic waves into an area downstream from the ultrasonic wave source bounded by a first plane parallel to the downstream direction and a second plane orthogonal to the first plane.

Abstract: An acoustic airspeed sensor system can include at least one acoustic transmitter configured to provide an acoustic pulse, a plurality of acoustic receivers including at least a first acoustic receiver, a second acoustic, receiver, and a third acoustic receiver, each positioned at a first radial distance from the at least one acoustic transmitter. The first acoustic receiver, the second acoustic receiver, and the third acoustic receiver are each configured to receive the acoustic pulse at a first time, a second time, and a third time, respectively, and output a first receiver signal, a second receiver signal, and a third receiver signal respectively. The system can include a computation unit operatively connected to the acoustic receivers and configured to generate a propagation function. The computation unit is further configured to determine true air speed based upon a receiver signals and the propagation function.

Abstract: An acoustic airspeed sensor system can include at least one acoustic transmitter configured to provide an acoustic pulse, a plurality of acoustic receivers including at least a first acoustic receiver, a second acoustic, receiver, and a third acoustic receiver, each positioned at a first radial distance from the at least one acoustic transmitter. The first acoustic receiver, the second acoustic receiver, and the third acoustic receiver are each configured to receive the acoustic pulse at a first time, a second time, and a third time, respectively, and output a first receiver signal, a second receiver signal, and a third receiver signal respectively. The system can include a computation unit operatively connected to the acoustic receivers and configured to generate a propagation function. The computation unit is further configured to determine true air speed based upon a receiver signals and the propagation function.

Abstract: An ultrasonic air data system (UADS) can include a body configured to mount to an aircraft, an acoustic signal shaping feature associated with the body, and an acoustic source operatively connected to the acoustic signal shaping feature, the acoustic source configured to emit a directional acoustic signal. The acoustic signal shaping feature can be configured to reshape the directional acoustic signal from the acoustic source into an at least partially reshaped signal. The system can include one or more acoustic receivers disposed on or at least partially within the body for receiving the reshaped signal.

Abstract: An ultrasonic air data system (UADS) can include a body configured to mount to an aircraft, an acoustic signal shaping feature associated with the body, and an acoustic source operatively connected to the acoustic signal shaping feature, the acoustic source configured to emit a directional acoustic signal. The acoustic signal shaping feature can be configured to reshape the directional acoustic signal from the acoustic source into an at least partially reshaped signal. The system can include one or more acoustic receivers disposed on or at least partially within the body for receiving the reshaped signal.

Abstract: An acoustic air data sensor for an aircraft includes an acoustic transmitter, an acoustic receiver, an acoustic signal generator, timing circuitry, speed of sound determination circuity, and communication circuitry. The acoustic transmitter is located to transmit an acoustic signal through an airflow stagnation chamber that is pneumatically connected to an exterior of the aircraft and configured to receive and stagnate airflow from the exterior of the aircraft. The acoustic receiver is positioned at a distance from the acoustic transmitter to receive the acoustic signal. The pulse generator causes the acoustic transmitter to provide the acoustic signal. The timing circuitry determines a time of flight of the acoustic signal from the acoustic transmitter to the acoustic receiver. The speed of sound determination circuity determines, based on the time of flight and the distance, a speed of sound through air in the stagnation chamber. The communication circuitry outputs the speed of sound.

Abstract: An acoustic air data sensor for an aircraft includes an acoustic transmitter, an acoustic receiver, an acoustic signal generator, timing circuitry, speed of sound determination circuity, and communication circuitry. The acoustic transmitter is located to transmit an acoustic signal through an airflow stagnation chamber that is pneumatically connected to an exterior of the aircraft and configured to receive and stagnate airflow from the exterior of the aircraft. The acoustic receiver is positioned at a distance from the acoustic transmitter to receive the acoustic signal. The pulse generator causes the acoustic transmitter to provide the acoustic signal. The timing circuitry determines a time of flight of the acoustic signal from the acoustic transmitter to the acoustic receiver. The speed of sound determination circuity determines, based on the time of flight and the distance, a speed of sound through air in the stagnation chamber. The communication circuitry outputs the speed of sound.

Abstract: An acoustic air data sensing system includes an acoustic transmitter, a plurality of acoustic receivers, and a skin friction sensor. The acoustic transmitter is located to transmit an acoustic signal into airflow about an exterior of a vehicle. Each of the acoustic receivers is located at a respective angle from a wind angle reference line and a respective distance from the acoustic transmitter. The skin fiction sensor is positioned in a boundary layer region of the airflow that interacts with the acoustic receivers and transmitter. Based on time of flight values of the acoustic signal from the transmitter to each of the receivers and a skin friction measurement from the skin friction sensor as inputs to a transformation matrix, the acoustic air data sensing system outputs, from the transformation matrix, the true airspeed, the relative wind angle, and the speed of sound for operational control of the vehicle.

Abstract: An ultrasonic air data system can include a pole having a length longer than a boundary layer thickness of a boundary layer flow such that at least a distal end of the pole is configured to extend outwardly from an aircraft surface to be at least partially outside of the boundary layer flow. The system can include a transmitter disposed on or in the pole at or near the distal end of the pole such that the transmitter is located at least partially outside of the boundary layer flow when in use, wherein the transmitter is configured to output a transmitter signal. The system can include one or more receivers disposed downstream of the pole as defined by the boundary layer flow and configured to receive the transmitter signal.

Abstract: An acoustic air data sensing system includes an acoustic transmitter, a plurality of acoustic receivers, and a skin friction sensor. The acoustic transmitter is located to transmit an acoustic signal into airflow about an exterior of a vehicle. Each of the acoustic receivers is located at a respective angle from a wind angle reference line and a respective distance from the acoustic transmitter. The skin fiction sensor is positioned in a boundary layer region of the airflow that interacts with the acoustic receivers and transmitter. Based on time of flight values of the acoustic signal from the transmitter to each of the receivers and a skin friction measurement from the skin friction sensor as inputs to a transformation matrix, the acoustic air data sensing system outputs, from the transformation matrix, the true airspeed, the relative wind angle, and the speed of sound for operational control of the vehicle.

Abstract: Aspects of the disclosure are directed to a system associated with an engine of an aircraft comprising: a duct, an inlet coupled to the duct, and a fence coupled to the inlet or located upstream of the inlet. In some embodiments, the system further comprises a valve body coupled to the duct. In some embodiments, the valve body includes at least one valve that is configured to rotate between a closed state and an open state.

Abstract: A rotor blade includes an elongated body having a leading edge, a trailing edge, a proximal end, and a distal end; a fluid inlet; a fluid outlet arranged near the distal end of the elongated body; and a fluid duct contained within the elongated body, the fluid duct being substantially open between the fluid inlet and the fluid outlet, the fluid duct having a shape to reduce fluid velocities C generated by the interaction of fluid exiting the fluid duct and external fluid at the distal end.

Abstract: Aspects of the disclosure are directed to a system associated with an engine of an aircraft comprising: a duct, an inlet coupled to the duct, and a fence coupled to the inlet or located upstream of the inlet. In some embodiments, the system further comprises a valve body coupled to the duct. In some embodiments, the valve body includes at least one valve that is configured to rotate between a closed state and an open state.

Abstract: A propeller is provided including a hub and a first blade group and a second blade group. The first blade group includes at least one first propeller blade and the second blade group includes at least one second propeller blade. The at least one first propeller blade and the at least one second propeller blade are mounted to and equidistantly spaced about the hub. The at least one first propeller blade of the first blade group has at least one geometric characteristic different from the at least one propeller blade of the second blade group. The different blade groups will generate different noise signatures over a wider range of frequencies allowing for the design of low noise propeller systems.

Abstract: A propeller is provided including a hub and a first blade group and a second blade group. The first blade group includes at least one first propeller blade and the second blade group includes at least one second propeller blade. The at least one first propeller blade and the at least one second propeller blade are mounted to and equidistantly spaced about the hub. The at least one first propeller blade of the first blade group has at least one geometric characteristic different from the at least one propeller blade of the second blade group. The different blade groups will generate different noise signatures over a wider range of frequencies allowing for the design of low noise propeller systems.

Abstract: A sound enhancement device for a detector includes a cylindrical portion having a tubular body and an interior cavity longitudinally coextensive therewith. The device includes a first elongated portion and at least a second elongated portion with both portions coupled to the cylindrical portion. The first elongated portion includes a first body portion having a first cavity that is coextensive with the first body portion while the at least second elongated portion includes a second body portion having a second cavity that is coextensive with the second body portion. The cylindrical portion and each of the first and at least the second elongated portions comprise a length of a quarter wavelength of a predefined frequency. The sound enhancement device includes radii of curvatures for causing a wavefront emanating from the sound enhancement device to maximize the radiation efficiency of the sound enhancement device.