Dual heated ramp for ice and water management in angle of attack sensors

An angle of attack sensor includes a vane assembly and a multi-piece faceplate adjacent the vane assembly. The faceplate includes a mounting plate having an opening and a heated chassis positioned adjacent the mounting plate and having a ring portion extending through the opening, the ring portion defining a ring-shaped deflector that surrounds the vane assembly and extends beyond an exterior surface of the mounting plate.

BACKGROUND

The present disclosure relates to sensors, and in particular, to angle of attack sensors.

Angle of attack sensors with rotatable vanes are installed on the exterior of aircraft to measure the aircraft angle of attack, the angle between oncoming airflow and the aircraft zero line (a reference line of the aircraft, such as a chord of a wing of the aircraft). The angle of attack sensor is mounted to the aircraft such that the rotatable vane protrudes outside the aircraft and is exposed to oncoming airflow. Aerodynamic forces acting on the rotatable vane cause the vane to align with the direction of the oncoming airflow. Rotational position of the vane is sensed and used to determine the aircraft angle of attack.

Oncoming airflow may contain water or ice particles that collect on the exterior surface, or faceplate, of the angle of attack sensor. The water can freeze onto the faceplate and accumulate near the vane. Large ice growths near the vane can interfere with the accuracy of the angle of attack sensor output.

SUMMARY

An angle of attack sensor includes a vane assembly and a multi-piece faceplate adjacent the vane assembly. The faceplate includes a mounting plate having an opening and a heated chassis positioned adjacent the mounting plate and having a ring portion extending through the opening, the ring portion defining a ring-shaped deflector that surrounds the vane assembly and extends beyond an exterior surface of the mounting plate.

A method for preventing significant ice accumulation on a faceplate adjacent a vane assembly, the faceplate including a heated chassis adjacent a mounting plate, includes re-routing fluid and particles away from an exterior surface of the mounting plate with a fore ramp of a deflector defined by the heated chassis and re-routing fluid away from the exterior surface of the mounting plate with an aft ramp of the deflector.

A heated chassis for use in an angle of attack sensor having a vane assembly and a multi-piece faceplate including a mounting plate with an opening, is positioned adjacent the mounting plate. The heated chassis includes a pocket within which a portion of the vane assembly is positioned and a ring portion extending through the opening of the mounting plate and defining a heated ring-shaped deflector that surrounds the vane assembly and extends beyond an exterior surface of the mounting plate.

DETAILED DESCRIPTION

In general, the present disclosure describes a multi-piece faceplate of an angle of attack (AOA) sensor that includes a mounting plate and a heated chassis having a ring portion extending past the exterior surface of the mounting plate, the ring portion defining a deflector including a fore ramp and an aft ramp. The fore ramp deflects ice or water moving along an upstream portion of the exterior surface of the faceplate away from the faceplate, minimizing the opportunity for ice accumulation on the faceplate. The aft ramp routes fluid away from the exterior surface of the faceplate to prevent the fluid from running back and forming ice growths near and aft of the vane. The deflector prevents nucleation of ice accumulation that could affect movement of the vane and alter sensor output, without increasing part count or changing the existing heater architecture.

FIG. 1Ais a top view of angle of attack sensor10.FIG. 1Bis a partial isometric top view of angle of attack sensor10.FIG. 1Cis a partial cross-sectional side view of angle of attack sensor10. Vane assembly22is not shown in cross-section inFIG. 1C. A lower portion of angle of attack sensor10has been omitted fromFIGS. 1B and 1Cfor simplicity.FIGS. 1A, 1B, and 1Cwill be discussed together.

Faceplate12is a multi-piece faceplate that includes mounting plate14, or outer faceplate, and heated chassis16, or inner faceplate. Mounting plate14is adjacent heated chassis16. Heated chassis16is made of thermally conductive material. In this embodiment, heated chassis16is made of aluminum. In alternate embodiments, heated chassis16may include copper, other metals, metal alloys, or any other suitable thermally conductive material. Air gap18is a space between mounting plate14and heated chassis16that fills with air (or other insulating material). Mounting plate14is positioned on heated chassis16such that heated chassis16is located inward from or interior to mounting plate14with respect to housing20. Housing20is cylindrical with an annular sidewall between an open first end and a closed second end. Faceplate12is positioned on housing20adjacent the open first end of housing20. More specifically, heated chassis16is positioned within and connected to the open first end of housing20such that heated chassis16seals the open first end of housing20. Mounting plate14is positioned on heated chassis16such that mounting plate14is adjacent the open first end of housing20and is outward from or exterior to heated chassis16. As such, mounting plate14is an outer piece of faceplate12and heated chassis16is an inner piece of faceplate12. Fasteners (not shown) connect mounting plate14and heated chassis16.

Vane assembly22is adjacent faceplate12. Vane assembly22, which includes vane base24and vane26, has a portion that is positioned in heated chassis16and extends through mounting plate14. More specifically, vane base24is positioned in heated chassis16. A first end of vane26is connected to vane base24. Vane26extends through mounting plate14. Annular gap28is adjacent vane base24. Annular gap28is a space that surrounds vane base24. Heated chassis16surrounds annular gap28. As such, annular gap28is between vane base24and heated chassis16. Consequently, annular gap28acts as a representation of the boundary between parts that rotate, such as vane24and vane base24, and parts that do not rotate, such as mounting plate14and heated chassis16. Vane base24receives shaft connectors30. Shaft connectors30extend through vane base24. A first end of rotatable vane shaft32is connected to vane base24via shaft connectors30. A second end of vane shaft32extends into housing20. Counterweight34is mounted on the second end of vane shaft32. As such, vane base24, vane shaft32, and counterweight34are configured to rotate together. Heater36is positioned on, or embedded in, heated chassis16. Heater36is annular, extending all the way around an end of heated chassis16within housing20. Heater36may be a self-regulating heater, a thermostatically controlled heater, or any other suitable heater.

Mounting plate14has interior surface38facing toward an interior of angle of attack sensor10. Interior surface38faces heated chassis16. Exterior surface40of mounting plate14is the surface opposite interior surface38, or the surface of mounting plate14that faces external airflow. Mounting plate14has circular opening42at its center, opening42extending from interior surface38to exterior surface40. Vane assembly22extends through mounting plate14at opening42. More specifically, vane26extends through opening42. Mounting holes44are located around a periphery of mounting plate14. Mounting holes44extend through mounting plate14from interior surface38to exterior surface40. In this embodiment, mounting plate14has eight mounting holes44. In alternate embodiments, mounting plate14may have any number of mounting holes44. Upstream portion46is a portion of mounting plate14that is upstream with respect to oncoming airflow when angle of attack sensor10is installed on an aircraft. Downstream portion48is a portion of mounting plate14that is downstream from upstream portion46(and downstream with respect to oncoming airflow) when angle of attack sensor10is installed on an aircraft. Downstream portion48is adjacent upstream portion46.

Heated chassis16includes ring portion50. Ring portion50is an annular portion of heated chassis16that extends into and through opening42of mounting plate14such that ring portion50extends above, or beyond, exterior surface40of mounting plate14. Ring portion50has a constant width. Opening42extends around ring portion50, and ring portion50extends around vane assembly22. Annular gap28is between ring portion50and vane assembly22, such that ring portion50also surrounds annular gap28. Heated chassis16defines pocket52, within which a portion of vane assembly22is positioned. Specifically, vane base24of vane assembly22is positioned within pocket52.

Ring portion50defines deflector54. Deflector54is a ring-shaped water and ice deflector. Deflector54fully surrounds vane assembly22and extends above, or beyond, exterior surface40of mounting plate14into oncoming airflow. Deflector54includes fore ramp56at a fore-located or upstream portion of deflector54forward of vane26. Aft ramp58is at an aft-located or downstream portion of deflector54rearward of vane26. Fore ramp56is connected to aft ramp58at a center, or a diameter, of deflector54. Deflector54, including fore ramp56and aft ramp58, is thermally coupled to heater36on heated chassis16. Fore ramp56and aft ramp58both have flat top surfaces.

Fore ramp56has a center section60positioned between tapered end sections62A and62B. Center section60extends above, or beyond, exterior surface40of mounting plate14and protrudes into oncoming airflow. The maximum height of fore ramp56is at center section60. In this embodiment, center section60has a constant height. Center section60is substantially normal to oncoming airflow when angle of attack sensor10is installed on an aircraft. Tapered end sections62A and62B decrease in height, or taper down, toward the center, or the diameter, of deflector54. In this embodiment, end portions of tapered end sections62A and62B at the diameter, or center line, of deflector54are about flush with exterior surface40of mounting plate14. Fore ramp56has inclined outer surface64at an outer surface of fore ramp56and vertical inner surface66at an inner surface of fore ramp56. Inclined outer surface64has an incline in an aft direction. Inclined outer surface64begins about flush with exterior surface40of mounting plate14and extends aft to a height above, or beyond, exterior surface40of mounting plate14. Vertical inner surface66is substantially vertical, or substantially perpendicular to exterior surface40of mounting plate14.

Aft ramp58has a center section68positioned between tapered end sections70A and70B. Center section68extends above, or beyond, exterior surface40of mounting plate14and protrudes into oncoming airflow. The maximum height of aft ramp58is at center section68. In this embodiment, center section68has a constant height. Center section68is substantially normal to oncoming airflow when angle of attack sensor10is installed on an aircraft. Tapered end sections70A and70B decrease in height toward the center, or the diameter, of deflector54. In this embodiment, end portions of tapered end sections70A and70B at diameter, or center line, of deflector54are about flush with exterior surface40of mounting plate14. Tapered end sections70A and70B taper down to meet end sections62A and62B of fore ramp56. As such, tapered end sections70A and70B of aft ramp58are connected to tapered end sections62A and62B of fore ramp56. Aft ramp58has inclined inner surface72at an inner surface of aft ramp58and vertical outer surface74at an outer surface of aft ramp58. Inclined inner surface72has an incline in an aft direction. Inclined inner surface72begins about flush with exterior surface40of mounting plate14and extends aft to a height above, or beyond, exterior surface40of mounting plate14. Vertical outer surface74is substantially vertical, or substantially perpendicular to exterior surface40of mounting plate14. Inclined outer surface64of fore ramp56is continuous with inclined inner surface72of aft ramp58.

Angle of attack sensors10are installed on the exterior of an aircraft and mounted to the aircraft via fasteners, such as screws or bolts, and mounting holes44on mounting plate14. As a result, mounting plate14is about flush or just below flush with the skin of the aircraft and housing20extends within an interior of the aircraft. Vane26extends outside an exterior of the aircraft and is exposed to oncoming airflow, causing vane26and vane base24of vane assembly22to rotate with respect to mounting plate14and heated chassis16via a series of bearings within angle of attack sensor10. Vane assembly22rotates based on the angle the aircraft is flying at relative to the oncoming airflow. More specifically, vane26rotates to be parallel with oncoming airflow. Vane26causes vane base24to rotate. Rotation of vane base24causes rotation of vane shaft32, which is coupled to a rotational sensor that measures the local angle of attack or angle of the airflow relative to the fixed aircraft structure. Counterweight34is mounted on vane shaft32to counterbalance vane26.

Heater36provides heat to heated chassis16. Heated chassis16is made of thermally conductive material so that heated chassis16can conduct heat to the rotating components of angle of attack sensor10, such as vane assembly22and vane shaft32. Ring portion50allows heated chassis16to extend up to the exposed exterior surface40of mounting plate14in an area surrounding vane assembly22to provide heat to vane assembly22. Ring portion50has a temperature above freezing in order to keep ice from forming on vane assembly22and in pocket52. Heater36also provides heat to deflector54of ring portion50. Heated chassis26maintains the area next to rotating components above freezing.

Mounting plate14is exposed to the external airflow, which is cold, and often contains water droplets or ice particles. A periphery of mounting plate14is also adjacent the aircraft skin, which is below freezing. Further, mounting plate14and heated chassis16are thermally isolated, such as by air gap18. Air gap38creates physical separation between mounting plate14and heated chassis16to limit conduction between mounting plate14and heated chassis16. Air gap38also reduces convection between mounting plate14and heated chassis16by creating insulation between mounting plate14and heated chassis16. Thus, portions of mounting plate14are below freezing, creating cold areas C. Areas of mounting plate14away from ring portion50, and rotating components, tend to be cold areas C. For example, a periphery of mounting plate14radially outward from housing20is thermally coupled with the aircraft skin, or aircraft mounting surface, making exterior surface40in that area significantly colder than exterior surface40in an area of mounting plate14adjacent heated chassis16.

On the other hand, mounting plate14can become relatively warm in some areas due to radiation and/or conduction from heater36through heated chassis16and/or warming of air gap18between mounting plate14and heated chassis16, creating warm areas W. For example, mounting plate14near ring portion50of heated chassis16is above freezing in certain environmental and flight conditions. As seen inFIG. 1A, warm areas W of mounting plate14are concentrated around ring portion50, where heat is concentrated.

Therefore, mounting plate14is above freezing in some areas and below freezing in other areas. Ice particles from oncoming airflow that impinge on exterior surface40of mounting plate14in warm areas W, such as near ring portion50, melt. Melting ice creates runback, or droplets of water that migrate aft toward exterior surface40of downstream portion48.

Oncoming airflow A is approximately normal, or perpendicular, to center section60of fore ramp56. As oncoming airflow A flows over faceplate12, inclined outer surface64of fore ramp56re-routes fluid and particles in oncoming airflow A from exterior surface40of mounting plate14. Fore ramp56deflects ice and water droplets away from exterior surface40of mounting plate14. Specifically, water droplets and/or ice particles from oncoming airflow A directly impinge on inclined outer surface64, which is angled to deflect, or throw, the particles back out into oncoming airflow A. Inclined inner surface72of aft ramp58re-routes fluid from exterior surface40of mounting plate14and heated chassis16. Aft ramp58captures runback water that gets around fore ramp56and re-routes the water away from exterior surface40of mounting plate14. As water flows over inclined inner surface52, water is redirected toward and released into the oncoming airflow away from exterior surface40of mounting plate14. Tapered end sections62A,62B,70A, and70B of fore ramp56and aft ramp58, respectively, prevent the induction of eddy currents or little air pockets that may cause airflow problems. Tapered end sections62A,62B,70A, and70B also shape deflector54in a way that allows deflector54be a single unitary piece with heated chassis16.

Runback water can re-freeze into ice when it encounters cold areas C of mounting plate14, such as aft of vane26(as seen inFIG. 1A) or when it reaches the aircraft skin at the periphery of mounting plate14. Such ice can create a nucleation site for ice accumulation, and ice crystals and/or super-cooled water droplets in the oncoming airflow can accumulate around the runback-initiated nucleation site. Ice accumulation can grow to a significant mass, building up to form large ice horns, near vane26, which can displace vane26and result in errant readings from angle of attack sensor10.

Fore ramp56minimizes the opportunity for precipitation to gather on exterior surface40of mounting plate14near vane assembly22. Fore ramp56deflects ice and water droplets away from exterior surface40of mounting plate14so water droplets cannot re-freeze aft of vane26. Aft ramp58carries precipitation away from exterior surface40of mounting plate14so that it cannot accumulate near vane26. Aft ramp58catches water in the vicinity of vane assembly22that was not deflected away by fore ramp56to prevent such water from running back along downstream portion48of mounting plate14and re-freezing on exterior surface40of mounting plate14in cold areas C aft of vane26. As such, deflector54controls precipitation around ring portion50to prevent significant ice accumulation on faceplate12in the vicinity of vane26, which could deflect vane26to a substantial degree and affect the output of angle of attack sensor10. By redirecting impinging ice or water away from exterior surface40of mounting plate14near vane assembly22, deflector54prevents nucleation of ice accumulation aft of vane26, eliminating deflection of vane26due to localized aerodynamics caused by ice accumulation in the vicinity of vane26. Further, because deflector54is heated, impinging water does not re-freeze or build up onto deflector54itself or form ice growths just upstream of vane assembly22.

Deflector54can be incorporated into the existing structure of faceplate12(such that mounting plate14is still removable without removing heated chassis16) and uses the existing architecture of heater36, avoiding a change to the heating scheme of angle of attack sensor10. Further, deflector54is unitary with ring portion50of heated chassis16, and thus, does not increase part count of angle of attack sensor10.

DISCUSSION OF POSSIBLE EMBODIMENTS

An angle of attack sensor includes a vane assembly; and a multi-piece faceplate adjacent the vane assembly, the faceplate including: a mounting plate having an opening; and a heated chassis positioned adjacent the mounting plate and having a ring portion extending through the opening, the ring portion defining a ring-shaped deflector that surrounds the vane assembly and extends beyond an exterior surface of the mounting plate.

The angle of attack sensor of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

The deflector includes: a fore ramp at an upstream portion of the deflector; and an aft ramp at a downstream portion of the deflector.

The fore ramp includes: tapered end sections; and a center section between tapered end sections.

The center section of the fore ramp extends beyond the exterior surface of the mounting plate.

The center section of the fore ramp is configured to be substantially normal to oncoming airflow when the angle of attack sensor is installed on an aircraft.

The aft ramp includes: tapered end sections; and a center section between tapered end sections.

The center section of the aft ramp extends beyond the exterior surface of the mounting plate.

The center section of the aft ramp is configured to be substantially normal to oncoming airflow when the angle of attack sensor is installed on an aircraft.

The fore ramp includes: an inclined outer surface with an incline in an aft direction; and a vertical inner surface substantially perpendicular to the exterior surface of the mounting plate; and the aft ramp includes: an inclined inner surface with an incline in the aft direction; and a vertical outer surface substantially perpendicular to the exterior surface of the mounting plate.

The inclined outer surface is continuous with the inclined inner surface.

The deflector is configured to redirect impinging ice or water away from exterior surface of mounting plate.

The deflector is heated.

The angle of attack sensor further includes a heater thermally coupled to the deflector and positioned on the heated chassis.

A method for preventing significant ice accumulation on a faceplate adjacent a vane assembly, the faceplate including a heated chassis adjacent a mounting plate, includes re-routing fluid and particles away from an exterior surface of the mounting plate with a fore ramp of a deflector defined by the heated chassis; and re-routing fluid away from the exterior surface of the mounting plate with an aft ramp of the deflector.

Re-routing fluid away from the exterior surface of the mounting plate with an aft ramp of the deflector includes capturing the fluid and releasing the fluid into oncoming airflow.

A heated chassis for use in an angle of attack sensor having a vane assembly and a multi-piece faceplate including a mounting plate with an opening, the heated chassis positioned adjacent the mounting plate and including a pocket within which a portion of the vane assembly is positioned; and a ring portion extending through the opening of the mounting plate and defining a heated ring-shaped deflector that surrounds the vane assembly and extends beyond an exterior surface of the mounting plate.

A fore ramp at an upstream portion of the deflector forward of the vane; and an aft ramp at a downstream portion of the deflector rearward of the vane.

The fore ramp includes: tapered end sections; and a center section between tapered end sections; and the aft ramp includes: tapered end sections; and a center section between tapered end sections.

The fore ramp includes: an inclined outer surface with an incline in an aft direction; and a vertical inner surface substantially perpendicular to the exterior surface of the mounting plate; and the aft ramp includes: an inclined inner surface with an incline in the aft direction; and a vertical outer surface substantially perpendicular to the exterior surface of the mounting plate.

The inclined outer surface is continuous with the inclined inner surface.