Patent Description:
Modern aircraft often incorporate air data systems that calculate air data outputs based on measured parameters collected from various sensors positioned about the aircraft. For instance, many air data systems utilize air data probes that measure pneumatic pressure of airflow about the aircraft exterior to generate aircraft air data outputs, such as angle of attack (i.e., an angle between the oncoming airflow or relative wind and a reference line of the aircraft, such as a chord of a wing of the aircraft), calibrated airspeed, Mach number, altitude, or other air data parameters. During sideslip of the aircraft (i.e., a nonzero angle between the direction of travel of the aircraft and the aircraft centerline extending through the nose of the aircraft), compensation of various local (to the probe) parameters or signals, such as angle of attack and static pressure, is advantageous for accurate determination of aircraft air data parameters, such as aircraft angle of attack or aircraft pressure altitude (determined from static pressure measurements). The air data probes may also be paired with temperature sensors in order to determine static air temperature, total air temperature, and true airspeed.

Increased accuracy achieved through sideslip compensation is particularly relevant in modern aircraft employing advanced control mechanisms that operate in the National Airspace System, as well as to accommodate fly-by-wire or other control systems that may benefit from increased accuracy achieved through sideslip compensation. To this end, many air data systems utilize multiple pneumatic air data probes positioned at opposite sides of the aircraft and cross-coupled to exchange pressure information. Static pressure sensed by an opposite side probe is used to compensate air data parameter outputs for a sideslip condition. In certain air data systems, cross-coupled probes are pneumatically connected so that the pressure signals are averaged between probes.

As aircraft systems such as flight control systems and stall protection systems become more highly integrated, complex, and automated, the integrity of air data information used by these aircraft systems becomes increasingly important. Air data sensors such as a pitot-static probes, angle of attack vanes, total air temperature (TAT) probes, and other air data sensors that extend into the airflow about the exterior of the aircraft can be susceptible to icing conditions as water vapor in the airflow impinges on the exposed sensor, thereby requiring anti-icing (e.g., heater) components and the electrical power budget associated therewith. Moreover, such sensors that extend into the oncoming airflow can increase drag on the aircraft, thereby reducing efficiency of flight. <CIT>describes an apparatus and method for unmanned aerial vehicle ground proximity detection. <CIT> describes a grounding detecting device for a skid type airplane. <CIT> describes an optical air data system. <CIT> describes an acoustic airspeed measurement system and method.

A system is described herein and defined in claim <NUM>.

A method is also described herein and defined in claim <NUM>.

As described herein, example air data system architectures include low-profile (e.g., flush with the aircraft skin) sensors that provide multiple (e.g., two, three, or more) independent sets of air data parameter outputs for use by consuming aircraft systems, such as automatic flight control systems, flight management systems, avionics systems, cabin pressurization and/or air management systems, or other consuming systems. The example architectures utilize combinations of laser air data sensors and acoustic air data sensors to provide air data parameter outputs, such as aircraft altitude, airspeed (e.g., true airspeed and/or calibrated airspeed), angle of attack, angle of sideslip, Mach number, or other air data parameter outputs that are derived from dissimilar technologies (i.e., optical and acoustic technologies) having dissimilar failure modes, thereby increasing availability and reliability of the air data systems. In some examples, pneumatic static pressure sensors that are disposed, e.g., flush with the aircraft skin, can be utilized in combination with the laser air data sensors and acoustic air data sensors to further increase diversity of the utilized technologies, thereby further increasing system reliability and safety while maintaining the low profile aspects of the air data systems.

<FIG> is a schematic block diagram illustrating system <NUM> including laser air data sensor <NUM> and acoustic air data sensor <NUM> that provide air data parameter outputs to one or more consuming systems <NUM>. Acoustic air data sensor <NUM>, as illustrated in <FIG>, includes acoustic transmitter <NUM>, acoustic receivers 20A, 20B, 20C, and 20D, and static pressure port <NUM>.

Laser air data sensor <NUM> and acoustic air data sensor <NUM> are configured to be mounted on an aircraft to generate air data parameter outputs that are provided to consuming systems <NUM> for operational control of the aircraft. Each of laser air data sensor <NUM> and acoustic air data sensor <NUM> can be mounted on the aircraft such that an exterior face of the sensor is flush with the aircraft exterior (e.g., the aircraft skin). While illustrated and described in the example of <FIG> as including a single laser air data sensor <NUM> and a single acoustic air data sensor <NUM>, it should be understood that system <NUM> can include any one or more laser air data sensors and any one or more acoustic air data sensors. In some examples, system <NUM> can include one or more pneumatic static pressure ports (e.g., flush static ports) that sense static pressure of the air about the aircraft exterior and provide the sensed static pressure to one or more of the laser and/or acoustic air data sensors, as is further described below.

Laser air data sensor <NUM> is configured to emit directional light (e.g., laser light) through a window or other optical element into the atmosphere. For instance, in some examples, laser air data sensor <NUM> is configured to emit directional light along three or more axes into the airflow about the exterior of the aircraft. The three axes (or three of four or more axes) can, in certain examples, be mutually orthogonal, though the three axes need not be mutually orthogonal in all examples. In general, laser air data sensor <NUM> emits directional light into the airflow along three or more axes that are each angularly separated by a threshold angle (or angles) that enables identification of velocities of the airflow along each of the three or more distinct axes.

Laser air data sensor <NUM> receives returns of the directional light in each of the three or more axes due to reflection (or scattering) of the emitted directional light from molecules and/or aerosols that move with the airflow. For example, based on the returns of the emitted directional light off aerosols or other particulates in the air, known in the art as Mie scattering, laser air data sensor <NUM> can determine a line of sight Doppler shift of the emitted directional light along each respective axis. From the determined Doppler shifts, laser air data sensor <NUM> determines velocity information of the airflow in each of the three or more axes. Laser air data sensor <NUM> utilizes the velocity information of the airflow in each of the three or more axes to determine airspeed information as well as a relative wind angle of the airflow corresponding to angle of attack (i.e., an angle between the direction of the oncoming airflow or relative wind and a reference line of the aircraft, such as a chord of a wing of the aircraft) and angle of sideslip (i.e., angle between the direction of the oncoming airflow or relative wind and an aircraft centerline extending through the nose of the aircraft). As such, laser air data sensor <NUM> determines, based on the returns of the emitted directional light, aircraft air data parameter outputs, such as aircraft angle of attack, aircraft angle of sideslip, aircraft true airspeed, or other air data parameter outputs.

In some examples, laser air data sensor <NUM> can be a molecular-based laser air data sensor that receives returns of emitted directional light off molecules in the air, known in the art as Rayleigh scattering. In such examples, laser air data sensor <NUM> can additionally determine, based on the Rayleigh scattering, density information of the air from which laser air data sensor <NUM> can derive static pressure and static temperature of the airflow about the aircraft exterior. Laser air data sensor <NUM> utilizes the static pressure and static temperature information to determine pressure and temperature-based air data parameter outputs, such as altitude, Mach number, or other pressure and/or temperature-based air data parameter outputs.

As illustrated in <FIG>, acoustic air data sensor <NUM> includes acoustic transmitter <NUM> and acoustic receivers 20A-20D. Acoustic transmitter <NUM> can be a piezoelectric speaker, a cone speaker, a micro-electro-mechanical systems (MEMS) speaker, or other electric-to-acoustic transducer. Acoustic receivers 20A-20D can be microphones including MEMS microphones, condenser microphones, or other acoustic-to-electric transducers.

Acoustic air data sensor <NUM> is configured to emit acoustic signals from acoustic transmitter <NUM> that are influenced by the airflow over the aircraft exterior as the acoustic signals propagate to acoustic receivers 20A-20D. Acoustic signals emitted by acoustic transmitter <NUM> can take the form of an acoustic pulse, an oscillating acoustic signal, a broadband acoustic signal, a random source acoustic signal, or other form of acoustic signal. In some examples, acoustic signals emitted by acoustic transmitter <NUM> can be ultrasonic acoustic signals, such as signals having a frequency greater than <NUM> kilohertz (kHz). In other examples, acoustic signals emitted by acoustic transmitter <NUM> can have a frequency that is in the audible range.

Acoustic receivers 20A-20D, in the example of <FIG>, are disposed at a known radius (r) from acoustic transmitter <NUM>. In some examples, the distance (r) between acoustic receivers 20A-20D and acoustic transmitter <NUM> can be a same distance. In other examples, the distance (r) between each of acoustic receivers 20A-20D and acoustic transmitter <NUM> can differ. For instance, the distance (r) between each of acoustic receivers 20A-20D and acoustic transmitter <NUM> can be between four and five inches, or other distances.

As illustrated in <FIG>, acoustic receivers 20A-20D are disposed about acoustic transmitter <NUM> such that axis (u) extending through acoustic receivers 20A and 20C is orthogonal to axis (w) extending through acoustic receivers 20B and 20D. Though illustrated and described in the example of <FIG> as including four acoustic receivers 20A-20D, it should be understood that acoustic air data sensor <NUM> can include more than four acoustic receivers, such as five or more acoustic receivers disposed about acoustic transmitter <NUM> at regular or irregular angular intervals.

Each of acoustic receivers 20A-20D receives the emitted acoustic signal at varying times, as the propagation of the emitted acoustic signal is influenced by the airflow over the aircraft exterior. Based on the known distance (r) between each of acoustic receivers 20A-20D and acoustic transmitter <NUM>, acoustic air data sensor <NUM> determines a time of flight of the acoustic signal between acoustic transmitter <NUM> and each of acoustic receivers 20A-20D. Using two of acoustic receivers 20A-20D along a same axis (e.g., acoustic receivers 20A and 20C along axis w, or acoustic receivers 20B and 20D along axis u), acoustic air data sensor <NUM> determines a speed of sound in the direction of the two acoustic receivers.

For instance, acoustic air data sensor <NUM> can be positioned on a side of the aircraft. For an aircraft in the u-v-w three-dimensional space (e.g., the u axis extending along the body through the nose of the aircraft, the v axis orthogonal to the u axis and extending out through the side of the aircraft, and the w axis orthogonal to both the u and v axes and extending through the bottom of the aircraft), acoustic air data sensor <NUM> is positioned in the u-w geometric plane, as illustrated in <FIG>. Accordingly, acoustic receivers 20A and 20C can be used to obtain a velocity in the w axis direction, and acoustic receivers 20B and 20D can be used to obtain a velocity in the u axis direction. The two determined velocities can be used to form a two-dimensional velocity vector for the u-w plane. Acoustic air data sensor <NUM> can utilize the two-dimensional velocity vector of the airflow to determine a relative wind angle of the airflow about the exterior of the aircraft, the relative wind angle corresponding to angle of attack or angle of sideslip. Because, in this example, acoustic air data sensor <NUM> is positioned on the side of the aircraft (i.e., in the u-w plane), the two-dimensional velocity vector can be used to determine a relative wind angle corresponding to an angle of attack for the aircraft.

In some examples, acoustic air data sensor <NUM> can be positioned on a top or bottom of the aircraft, e.g., in the u-v plane. In such an example, acoustic receivers 20A and 20C can be used to determine a velocity in the u axis direction (e.g., extending along the body of the aircraft through the nose of the aircraft), and acoustic receivers 20B and 20D can be used to determine a velocity in the v axis direction (e.g., orthogonal to the u axis and extending out through the side of the aircraft). Because, in such an example, acoustic air data sensor <NUM> is positioned on a top or bottom of the aircraft in the u-v plane, the two-dimensional velocity vector for the u-v plane can be used to determine a relative wind angle corresponding to an angle of sideslip of the aircraft.

In some examples, multiple (e.g., two or more) of acoustic air data sensor <NUM> can be positioned about the aircraft to obtain both angle of attack and angle of sideslip information. For instance, in certain examples, a first acoustic air data sensor <NUM> can be positioned on a side of the aircraft to obtain angle of attack information, and a second acoustic air data sensor <NUM> can be positioned on a top or bottom of the aircraft to obtain angle of sideslip information.

Acoustic air data sensor <NUM> can determine a static air temperature (SAT) of the airflow about the aircraft exterior, regardless of the orientation of acoustic air data sensor <NUM> as positioned on the exterior of the aircraft. For example, two of acoustic receivers 20A-20D positioned along a same axis (e.g., acoustic receivers 20A and 20C along axis w, or acoustic receivers 20B and 20D along axis u) can be used to sense acoustic signals emitted by acoustic transmitter <NUM>. Acoustic receiver 20B, for example, can be used to determine the time of flight of the acoustic signals upstream from acoustic transmitter <NUM>, and acoustic receiver 20D can be used to determine the time of flight of the acoustic signals downstream from acoustic transmitter <NUM>. Based on the known distance (or distances) between acoustic transmitter <NUM> and each of acoustic receivers 20A and 20D (distance (r) in the example of <FIG>), acoustic air data sensor <NUM> can determine the speed of sound in the airflow about the aircraft exterior. Acoustic air data sensor <NUM> can determine, based on the determined speed of sound, a static air temperature of the airflow, as is known in the art.

As illustrated in <FIG>, acoustic air data sensor <NUM> includes static pressure port <NUM>. Static pressure port <NUM> can be pneumatically connected (e.g., via tubing or other pneumatic connection) to a pressure transducer of acoustic air data sensor <NUM> to measure static pressure of the air about the exterior of the aircraft. In some examples, acoustic air data sensor <NUM> may not include static pressure port <NUM>, but rather may receive static pressure information from a separate static pressure sensor device, as is further described below. In certain examples, acoustic air data sensor <NUM> can receive static pressure information from a static pressure sensor device that is disposed on an opposite side of the aircraft from acoustic air data sensor <NUM> to determine an average of static air pressures on opposite sides of the aircraft to compensate for, e.g., local (to the aircraft) pressure effects at the sensors caused by non-zero sideslip conditions of the aircraft. Acoustic air data sensor <NUM> can utilize the measured static pressure information to determine air data parameter outputs, such as aircraft altitude, calibrated airspeed, or other air data parameters that are based on static air pressure.

Accordingly, system <NUM> including laser air data sensor <NUM> and acoustic air data sensor <NUM> can provide multiple sets of air data parameter outputs including, e.g., aircraft altitude, angle of attack, angle of sideslip, airspeed, Mach number, or other air data parameter outputs to consuming systems <NUM>. Such multiple sets of air data parameter outputs (i.e., provided by each of laser air data sensor <NUM> and acoustic air data sensor <NUM>) can increase reliability and availability of the air data parameter outputs for use by consuming systems <NUM> by virtue of redundancy of the air data parameter outputs as well as diversity of technologies by which the air data parameter outputs are sensed (i.e., both laser-based sensing and acoustic-based sensing). Moreover, the low-profile nature of both laser air data sensor <NUM> and acoustic air data sensor <NUM> (e.g., disposed flush with the aircraft skin) can help to reduce both drag on the aircraft and susceptibility of the sensors to failure modes associated with icing conditions.

<FIG> is a schematic block diagram illustrating air data system architecture 10A for providing air data parameter outputs to consuming systems <NUM>. As illustrated in <FIG>, architecture 10A includes laser air data sensors 24A and 24B, as well as acoustic air data sensor <NUM> mounted on aircraft <NUM>. In the example of <FIG>, laser air data sensor 24A is disposed on side <NUM> of aircraft <NUM>. Laser air data sensor 24B and acoustic air data sensor <NUM> are disposed on side <NUM> of aircraft <NUM>, opposite side <NUM>. In other examples, any one or more of laser air data sensors 24A and 24B as well as acoustic air data sensor <NUM> can be disposed on a same side of aircraft <NUM> (i.e., one of sides <NUM> and <NUM>), a top of aircraft <NUM>, a bottom of aircraft <NUM>, or combinations thereof.

Laser air data sensors 24A and 24B can be substantially similar to laser air data sensor <NUM> of <FIG>. In the example of <FIG>, each of laser air data sensors 24A and 24B is a molecular-based laser air data sensor configured to receive returns of emitted directional light off molecules in the air (i.e., Rayleigh scattering). As such, each of laser air data sensors 24A and 24B is configured to emit directional light in three or more directions into airflow about the aircraft exterior, and to determine air data parameters, such as aircraft angle of attack, aircraft angle of sideslip, airspeed, or other aircraft air data parameters based on velocities of the airflow along each respective axis based on the received returns of the emitted directional light. In addition, each of laser air data sensors 24A and 24B is configured to determine, based on the Rayleigh scattering, density information of the air from which laser air data sensors 24A and 24B derive static pressure and static temperature of the exterior airflow.

Acoustic air data sensor <NUM>, in the example of <FIG>, can be substantially similar to acoustic air data sensor <NUM> of <FIG>. In the example of <FIG>, however, acoustic air data sensor <NUM> does not include static port <NUM> (<FIG>). As such, acoustic air data sensor <NUM> is electrically connected to receive static pressure information from laser air data sensors 24A and 24B, though in other examples, acoustic air data sensor <NUM> can receive the static pressure information from only one of laser air data sensors 24A and 24B.

As illustrated in <FIG>, each of laser air data sensor 24A, laser air data sensor 24B, and acoustic air data sensor <NUM> is electrically connected to transmit air data parameter outputs to consuming systems <NUM>. In addition, in the example of <FIG>, acoustic air data sensor <NUM> is electrically connected to receive static pressure information from laser air data sensors 24A and 24B. Electrical connections illustrated in <FIG> can take the form of direct electrical couplings and/or data bus couplings configured to communicate according to one or more communication protocols, such as the Aeronautical Radio, Incorporated (ARINC) <NUM> communication protocol, controller area network (CAN) bus communication protocol, military standard <NUM> (MIL-STD-<NUM>) communication protocol, or other analog or digital communication protocols.

In operation, each of laser air data sensors 24A and 24B emits directional light into the airflow about the exterior of aircraft <NUM> along three or more axes. Laser air data sensors 24A and 24B each determine, based on received returns of the emitted directional light, air data parameters including, e.g., altitude (i.e., based on determined static pressure), airspeed (e.g., calibrated airspeed and/or true airspeed), Mach number, angle of attack, angle of sideslip, or other air data parameter outputs.

Acoustic air data sensor <NUM> emits acoustic signals into the airflow about the exterior of aircraft <NUM> and determines air data parameter outputs, such as airspeed and one of angle of attack or angle of sideslip (i.e., depending upon installation orientation, as described above with respect to the example of <FIG>). Acoustic air data sensor <NUM>, in the example of <FIG>, receives static pressure information from laser air data sensors 24A and 24B, and utilizes the static pressure information to generate pressure-based air data parameter outputs, such as altitude.

Each of laser air data sensor 24A, laser air data sensor 24B, and acoustic air data sensor <NUM> transmits the respective air data parameter outputs to consuming systems <NUM>. Consuming systems <NUM>, which can include aircraft systems such as flight management systems, auto-flight control systems, standby instrument systems, display systems, data concentrator units, or other consuming systems of the air data parameter outputs, utilize the air data parameter outputs for operational control of aircraft <NUM> (e.g., controlled flight or other operations). Accordingly, air data system architecture 10A provides three sets of air data parameter outputs (e.g., three redundant sets of information) to consuming systems <NUM>, thereby increasing system safety and reliability.

<FIG> is a schematic block diagram illustrating air data system architecture 10B for providing air data parameter outputs to consuming systems <NUM>. As illustrated in <FIG>, architecture 10B includes laser air data sensors 24A and 24B, acoustic air data sensor <NUM>, and static pressure sensor 34A. In the example of <FIG>, laser air data sensor 24A and static pressure sensor 34A are disposed at side <NUM> of aircraft <NUM>, and laser air data sensor 24B and acoustic air data sensor <NUM> are disposed at side <NUM> of aircraft <NUM>. Each of laser air data sensors 24A and 24B, as described above with respect to <FIG>, are molecular-based laser air data sensors configured to determine air data parameter outputs, including static pressure-based and static air temperature-based air data parameter outputs (e.g., altitude, calibrated airspeed, or other parameters) derived from density information determined based on Rayleigh scattered returns of emitted directional light.

Acoustic air data sensor <NUM>, in this example, includes static pressure port <NUM> (and the associated pressure transducer) to measure static pressure of the external air, as was described above with respect to <FIG>. Static pressure sensor 34A, mounted flush with the exterior of aircraft <NUM>, includes a static pressure port pneumatically connected to a pressure transducer (not shown) for sensing static pressure of the air about the exterior of aircraft <NUM>.

As illustrated in <FIG>, each of laser air data sensor 24A, laser air data sensor 24B, and acoustic air data sensor <NUM> are electrically connected to transmit air data parameter outputs to consuming systems <NUM>. In addition, as illustrated in <FIG>, acoustic air data sensor <NUM> is electrically connected to static pressure sensor 34A to receive measured static pressure information from static pressure sensor 34A.

Acoustic air data sensor <NUM> can utilize the static pressure measured via static pressure port <NUM> in combination with the measured static pressure information received from cross-side static pressure sensor 34A (i.e., disposed on side <NUM>, opposite side <NUM>) to determine pressure-based air data parameters, such as altitude, calibrated airspeed, or other pressure-based air data parameters. For instance, because acoustic air data sensor <NUM> and static pressure sensor 34A measure static pressure from within the boundary layer of airflow over the exterior of aircraft <NUM> (e.g., within six inches from the exterior skin of aircraft <NUM>), such measured static pressures can be influenced by local airflow effects over the exterior of aircraft <NUM> that vary with, e.g., aircraft sideslip. As such, acoustic air data sensor <NUM> can average or otherwise combine the static pressure measured via static pressure port <NUM> and the static pressure received from static pressure sensor 34A (e.g., disposed at an opposite side of aircraft <NUM>) to compensate for local airflow effects caused by a sideslip condition. Acoustic air data sensor <NUM> can therefore determine pressure-based air data parameter outputs, such as altitude and calibrated airspeed, based on the averaged (or otherwise combined) static pressures measured at each of sides <NUM> and side <NUM> of aircraft <NUM>.

<FIG> is a schematic block diagram illustrating air data system architecture 10C for providing air data parameter outputs to consuming systems <NUM>. As illustrated in <FIG>, architecture 10C includes laser air data sensors 24A and 24B, acoustic air data sensor <NUM>, static pressure sensor 34A, and static pressure sensor 34B. In the example of <FIG>, laser air data sensor 24A and static pressure sensor 34A are disposed at side <NUM> of aircraft <NUM>. Laser air data sensor 24B, acoustic air data sensor <NUM>, and static pressure sensor 34B are disposed at side <NUM> of aircraft <NUM>.

Each of laser air data sensors 24A and 24B, as described above with respect to <FIG> and <FIG>, are molecular-based laser air data sensors configured to determine air data parameter outputs, including static pressure-based and static air temperature-based air data parameter outputs. Acoustic air data sensor <NUM>, as described above with respect to <FIG>, is similar to acoustic air data sensor <NUM> (<FIG> and <FIG>), but does not include a static pressure port (i.e., static pressure port <NUM>). Static pressure sensor 34B can be substantially similar to static pressure sensor 34A, described above with respect to <FIG> as including a static pressure port pneumatically connected to a pressure transducer to sense static pressure of the air about the exterior of aircraft <NUM>.

As illustrated in <FIG>, each of laser air data sensor 24A, laser air data sensor 24B, and acoustic air data sensor <NUM> are electrically connected to transmit air data parameter outputs to consuming systems <NUM>. In addition, as illustrated in <FIG>, acoustic air data sensor <NUM> is electrically connected to static pressure sensor 34A to receive measured static pressure information from static pressure sensor 34A, disposed at side <NUM> of aircraft <NUM>. Acoustic air data sensor is electrically connected to static pressure sensor 34B to receive measured static pressure information from static pressure sensor 34B, disposed at side <NUM> of aircraft <NUM>.

Acoustic air data sensor <NUM> can utilize the static press measurements received from static pressure sensor 34A and static pressure sensor 34B (i.e., cross-side static pressure sensors) to determine pressure-based air data parameters, such as altitude, calibrated airspeed, or other pressure-based air data parameters. For instance, acoustic air data sensor <NUM> can average or otherwise combine the static pressure measurements received from static pressure sensor 34A and static pressure sensor 34B. Accordingly, architecture 10C is similar to architecture 10B of <FIG>, but rather than include a static pressure sensor as integral to the acoustic air data sensor (e.g., static pressure port <NUM> of acoustic air data sensor <NUM> of <FIG>), acoustic air data sensor <NUM> receives static pressure measurement data from static pressure sensor 34B.

<FIG> is a schematic block diagram illustrating air data system architecture 10D for providing air data parameter outputs to consuming systems <NUM>. As illustrated in <FIG>, architecture 10D includes laser air data sensor 36A, laser air data sensor 36B, acoustic air data sensor <NUM>, static pressure sensor 34A, static pressure sensor 38A, static pressure sensor 38B, static pressure sensor 40A, and static pressure sensor 40B. In the example of <FIG>, laser air data sensor 36A, static pressure sensor 34A, static pressure sensor 38A, and static pressure sensor 40A are disposed at side <NUM> of aircraft <NUM>. Laser air data sensor 36B, static pressure sensor 40B, static pressure sensor 38B, and acoustic air data sensor <NUM> are disposed at side <NUM> of aircraft <NUM>.

Each of static pressure sensors 38A, 38B, 40A, and 40B can be substantially similar to static pressure sensor 34A, described above with respect to <FIG> and <FIG> as including a static pressure port pneumatically connected to a pressure transducer to sense static pressure of air about the exterior of aircraft <NUM>. Acoustic air data sensor <NUM>, as described above with respect to <FIG> and <FIG>, includes static pressure port <NUM> pneumatically connected to a pressure transducer to sense static pressure of the air about the exterior of aircraft <NUM>. In addition, acoustic air data sensor <NUM> is electrically connected to receive static pressure measurement information from static pressure sensor 34A (disposed on side <NUM> of aircraft <NUM>).

In the example of <FIG>, each of laser air data sensors 36A and 36B is a particulate-based laser air data sensor configured to determine air data parameter outputs based on returns of emitted directional light off aerosols or other particulates in the air (i.e., Mie scattering). As such, rather than determine pressure and temperature information based on returns of emitted directional light, laser air data sensors 36A and 36B receive pressure information from static pressure sensors 38A, 38B, 40A, and 40B, and static air temperature information from acoustic air data sensor <NUM>.

For example, as illustrated in <FIG>, laser air data sensor 36A is electrically connected to receive static pressure information from static pressure sensor 38A (disposed on side <NUM> of aircraft <NUM>) and from static pressure sensor 38B (disposed on side <NUM> of aircraft <NUM>). Laser air data sensor 36B is electrically connected to receive static pressure information from static pressure sensor 40A (disposed on side <NUM> of aircraft <NUM>) and from static pressure sensor 40B (disposed on side <NUM> of aircraft <NUM>). In addition, as illustrated in <FIG>, laser air data sensors 36A and 36B are electrically connected to receive static air temperature measurement information from acoustic air data sensor <NUM>. Laser air data sensors 36A and 36B utilize the received static air temperature information for determining temperature-based air data parameter outputs, such as Mach number.

In operation, each of laser air data sensors 36A and 36B emits directional light along three or more axes into the airflow about the exterior of aircraft <NUM>. Each of laser air data sensors 36A and 36B determines, based on returns of the emitted directional light (i.e., based on Mie scattering off aerosols or other particulates in the air), velocity information along each of the three or more axes. Laser air data sensors 36A and 36B determine air data parameter outputs, such as airspeed, angle of attack, and angle of sideslip, based on the velocities in the three or more directions. Laser air data sensors 36A and 36B utilize measured static pressure data received from static pressure sensors 38A and 38B (i.e., utilized by laser air data sensor 36A) and static pressure sensors 40A and 40B (i.e., utilized by laser air data sensor 36B) to determine pressure-based air data parameter outputs, such as altitude, calibrated airspeed, or other pressure-based air data parameter outputs. Laser air data sensors 36A and 36B utilize measured static air temperature information received from acoustic air data sensor <NUM> to generate temperature-based air data parameter outputs, such as Mach number, or other temperature-based air data parameter outputs. Each of laser air data sensors 36A and 36B transmit, via aircraft communications data bus or otherwise, the determined set of air data parameter outputs to consuming systems <NUM>.

Acoustic air data sensor <NUM> generates air data parameter outputs, such as airspeed, Mach number, and one of angle of attack or angle of sideslip (i.e., depending upon installation orientation), based on acoustic signals transmitted and received by acoustic air data sensor <NUM>. Acoustic air data sensor <NUM> generates pressure-based air data parameter outputs, such as altitude, calibrated airspeed, or other pressure-based air data parameter outputs, based on static pressure measurements received via static pressure port <NUM> and cross-side static pressure sensor 34A. Acoustic air data sensor <NUM> transmits the determined set of air data parameter outputs to consuming systems <NUM>. Accordingly, laser air data sensor 36A, laser air data sensor 36B, and acoustic air data sensor <NUM> can each provide air data parameter outputs, including, e.g., aircraft altitude, angle of attack, angle of sideslip, airspeed, Mach number, or other air data parameter outputs to consuming systems <NUM>.

<FIG> is a schematic block diagram illustrating air data system architecture 10E for providing air data parameter outputs to consuming systems <NUM>. As illustrated in <FIG>, architecture 10E includes laser air data sensor 36A, laser air data sensor 36B, acoustic air data sensor <NUM>, static pressure sensor 34A, static pressure sensor 34B, static pressure sensor 38A, static pressure sensor 38B, static pressure sensor 40A, and static pressure sensor 40B. The example architecture 10E of <FIG> is similar to architecture 10D of <FIG>. However, rather than include acoustic air data sensor <NUM> having static pressure port <NUM> (<FIG>), architecture 10E includes acoustic air data sensor <NUM> that does not include a static pressure port. Accordingly, the example architecture 10E of <FIG> includes static pressure sensor 34B that provides measured static pressure information to acoustic air data sensor <NUM>.

In the example of <FIG>, laser air data sensor 36A, static pressure sensor 34A, static pressure sensor 38A, and static pressure sensor 40A are disposed at side <NUM> of aircraft <NUM>. Laser air data sensor 36B, static pressure sensor 40B, static pressure sensor 38B, static pressure sensor 34B, and acoustic air data sensor <NUM> are disposed at side <NUM> of aircraft <NUM>.

Each of laser air data sensors 36A and 36B, as described above with respect to the example of <FIG>, is a particulate-based laser air data sensor configured to determine air data parameter outputs based on returns of emitted directional light off aerosols or other particulates in the air (i.e., Mie scattering). Each of static pressure sensors 34A, 34B, 38A, 38B, 40A, and 40B includes a static pressure port (and corresponding pressure transducer) configured to measure static pressure of the airflow about the exterior of aircraft <NUM>.

Laser air data sensor 36A is electrically connected to receive static pressure information from static pressure sensor 38A (disposed on side <NUM> of aircraft <NUM>) and from static pressure sensor 38B (disposed on side <NUM> of aircraft <NUM>). Laser air data sensor 36B is electrically connected to receive static pressure information from static pressure sensor 40A (disposed on side <NUM> of aircraft <NUM>) and from static pressure sensor 40B (disposed on side <NUM> of aircraft <NUM>). In addition, as illustrated in <FIG>, laser air data sensors 36A and 36B are electrically connected to receive static air temperature measurement information from acoustic air data sensor <NUM>. Laser air data sensors 36A and 36B utilize the received static air temperature information for determining temperature-based air data parameter outputs, such as Mach number.

Acoustic air data sensor <NUM> generates air data parameter outputs, such as airspeed, Mach number, and one of angle of attack or angle of sideslip (i.e., depending upon installation orientation), based on acoustic signals transmitted and received by acoustic air data sensor <NUM>. Acoustic air data sensor <NUM> generates pressure-based air data parameter outputs, such as altitude, calibrated airspeed, or other pressure-based air data parameter outputs, based on static pressure measurements received from static pressure sensors 34A and 34B. Acoustic air data sensor <NUM> transmits the determined set of air data parameter outputs to consuming systems <NUM>. Accordingly, laser air data sensor 36A, laser air data sensor 36B, and acoustic air data sensor <NUM> can each provide air data parameter outputs, including, e.g., aircraft altitude, angle of attack, angle of sideslip, airspeed, Mach number, or other air data parameter outputs to consuming systems <NUM>.

Accordingly, techniques of this disclosure enable multiple (e.g., redundant) sets of air data parameter outputs (e.g., altitude, angle of attack, angle of sideslip, airspeed, Mach number, or other air data parameter outputs) to be provided to consuming systems <NUM> for use in operational control of an aircraft. Such multiple sets of air data parameter outputs can increase reliability and availability of the air data parameter outputs for use by consuming systems <NUM> by virtue of redundancy of the air data parameter outputs as well as diversity of technologies by which the air data parameter outputs are sensed. Moreover, the low-profile nature of the air data sensors described herein (e.g., disposed flush with the aircraft skin) can help to reduce both drag on the aircraft and susceptibility of the sensors to failure modes associated with icing conditions.

Any of the sensors and/or systems described herein can include one or more processors and computer-readable memory encoded with instructions that, when executed by the one or more processors, cause the sensors and/or systems to operate in accordance with techniques of this disclosure. Examples of one or more processors can include any one or more of a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry. Computer-readable memory of sensors and/or systems can be configured to store information within the corresponding sensors and/or systems during operation. The computer-readable memory can be described, in some examples, as computer-readable storage media. In some examples, a computer-readable storage medium can include a non-transitory medium. The term "non-transitory" can indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium can store data that can, over time, change (e.g., in RAM or cache). Computer-readable memory can include volatile and non-volatile memories. Examples of volatile memories can include random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), and other forms of volatile memories. Examples of non-volatile memories can include magnetic hard discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories.

Claim 1:
A system (<NUM>) comprising:
a first laser air data sensor (<NUM>, 25A)
configured to emit first directional light into airflow about an aircraft (<NUM>) exterior and to generate first air data parameter outputs for the aircraft based on returns of the emitted first directional light; and
an acoustic air data sensor (<NUM>, <NUM>) configured to:
emit acoustic signals into the airflow about the aircraft exterior;
sense the acoustic signals; and
generate second air data parameter outputs for the aircraft based on the sensed acoustic signals,
wherein the first laser air data sensor is a molecular-based laser air data sensor configured to:
receive the returns of the emitted first directional light scattered by air molecules within the airflow about the aircraft exterior; and
determine, based on the returns of the emitted first directional light scattered by the air molecules within the airflow, first static pressure of the airflow, first static air temperature of the airflow, first true airspeed of the airflow, and a first relative wind angle of the first laser air data sensor with respect to the airflow, and characterized in that the acoustic air data sensor is electrically coupled to receive the first static pressure of the airflow from the first laser air data sensor; and
wherein the acoustic air data sensor includes a static pressure port (<NUM>) or wherein the system comprises a first static pressure sensor (34B) electrically connected to the acoustic air data sensor, wherein the static pressure port (<NUM>) or the first static pressure sensor (34B) is configured to sense second static pressure of the airflow about the aircraft exterior; and
wherein the acoustic air data sensor is configured to determine the altitude of the aircraft based on the first static pressure of the airflow received from the first laser air data sensor and the second static pressure of the airflow sensed by the static pressure sensor; wherein the acoustic air data sensor is configured to generate the second air data parameter outputs as including the determined altitude.