Rotorcraft having an airspeed sensor located at the top of a tail fin of the rotorcraft
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B64D-043/02
G01P-005/26
G01P-005/00
G01P-013/02
출원번호
US-0708775
(2015-05-11)
등록번호
US-9415881
(2016-08-16)
우선권정보
FR-14 01064 (2014-05-12)
발명자
/ 주소
Certain, Nicolas
Delecroix, Olivier
출원인 / 주소
Airbus Helicopters
대리인 / 주소
Brooks Kushman P.C.
인용정보
피인용 횟수 :
0인용 특허 :
4
초록▼
A method of calculating and displaying the true airspeed of a rotorcraft. At least one omnidirectional airspeed sensor is installed at the top of a tail fin of the rotorcraft. The true airspeed of the rotorcraft flying at speeds that are lower than or equal to at least one airspeed threshold of the
A method of calculating and displaying the true airspeed of a rotorcraft. At least one omnidirectional airspeed sensor is installed at the top of a tail fin of the rotorcraft. The true airspeed of the rotorcraft flying at speeds that are lower than or equal to at least one airspeed threshold of the rotorcraft is calculated by correcting the measurements supplied by the airspeed sensor installed at the top of the tail fin as a function of the effects produced by the air stream generated by rotation of the main rotor of the rotorcraft on the characteristics of the speed of the air stream measured by the tail fin airspeed sensor. For this purpose, a correction rule calibrated in test flight is advantageously applied to correct the measurements supplied by the airspeed sensor installed at the top of the tail fin.
대표청구항▼
1. A method of calculating and displaying the true airspeed of a rotorcraft having at least one tail fin and at least one main rotor providing the rotorcraft essentially with its main lift, and a tail rotor providing the rotorcraft at least with guidance in yaw, the method comprising an operation of
1. A method of calculating and displaying the true airspeed of a rotorcraft having at least one tail fin and at least one main rotor providing the rotorcraft essentially with its main lift, and a tail rotor providing the rotorcraft at least with guidance in yaw, the method comprising an operation of calculating the true airspeed of the rotorcraft from measurements supplied by at least one omnidirectional airspeed sensor and a display operation of displaying on a screen the true airspeed of the rotorcraft as deduced by an operation of calculating, wherein the operation of calculating the true airspeed of the rotorcraft is performed on the basis of measurements supplied by at least one omnidirectional airspeed sensor installed at the top of the tail fin, the at least one omnidirectional airspeed sensor thus being referred to as the “tail fin airspeed sensor”. 2. A method according to claim 1, wherein the true airspeed of the rotorcraft flying at speeds lower than or equal to at least one predefined airspeed threshold of the rotorcraft is calculated by correcting the measurements supplied by the tail fin airspeed sensor as a function of effects produced by the stream of air generated by the rotation of the main rotor on the characteristics of the speed of the air stream measured by the tail fin airspeed sensor. 3. A method according to claim 2, wherein the correction of the measurements supplied by the tail fin airspeed sensor is performed by applying at least one correction rule correcting at least the amplitude values and the orientations relative to the axes in which the rotorcraft generally extends of the vector components of the speed of the air stream measured by the tail fin airspeed sensor. 4. A method according to claim 3, wherein the correction of the measurements supplied by the tail fin airspeed sensor further comprises data filtering applied to the data coming from the measurements supplied by the tail fin airspeed sensor, either before or after the correction applied to the measurements supplied by the tail fin airspeed sensor. 5. A method according to claim 3, wherein the correction of the measurements supplied by the tail fin airspeed sensor is performed more specifically in at least of the following manners: applying a phase correction correcting the individual angular orientation of each of the vector components of the speed of the air stream measured by the tail fin airspeed sensor relative to the longitudinally and transversely extending axes of the rotorcraft;applying an amplitude correction individually correcting the amplitudes of each of the vector components of the speed of the air stream measured by the tail fin airspeed sensor; andusing a lowpass filter to apply data filtering to the data coming from the measurements supplied by the tail fin airspeed sensor. 6. A method according to claim 3, wherein the correction rule incorporates parameters for correcting the measurements supplied by the tail fin airspeed sensor and having values that are identified by calibrating the correction rule in test flight. 7. A method according to claim 3, wherein the correction rule is made up of functions, some of which are affine functions, the functions being applied in succession to correct the measurements supplied by the tail fin airspeed sensor. 8. A method according to claim 7, wherein at least one of the affine functions includes a correction parameter taking account of a correction criterion relating to the mechanical power consumption of the main rotor. 9. A method according to claim 8, wherein the correction criterion is taken into account by taking account of the current collective pitch angle (APC) of the blades of the main rotor. 10. A method according to claim 8, wherein the correction criterion is taken into account by taking account of the resistive torque opposed by the main rotor against being driven in rotation by a power plant forming part of the rotorcraft. 11. A method according to claim 1, wherein the measurements supplied by the tail fin airspeed sensor are corrected by performing the following successive operations: applying first calculation functions calculating an airspeed of the rotorcraft, referred to as a “first” corrected airspeed (VC1), the first functions individually identifying a longitudinal component (VC1X) and a lateral component (VC1Y) of the first corrected airspeed (VC1) in the following manners: VC1X=VM*cos(VA+A1)VC1Y=VM*sin(VA+A2) in which first calculation functions, VC1X and VC1Y are the respective values of the longitudinal component and of the lateral component of the first corrected airspeed (VC1), VM is the amplitude of the speed of the air stream measured by the tail fin airspeed sensor, VA is the orientation direction of the airspeed measured by the tail fin airspeed sensor, and A1 and A2 are predefined angle correction constants for the vector components of the speed of the air stream measured by the tail fin airspeed sensor, the respective values of the constants A1 and A2 being identified by a calibration operation in test flight for the first calculation functions; applying affine second calculation functions calculating a second corrected airspeed (VC2), the second calculation functions identifying the amplitude values respectively of the longitudinal component (VC2X) and of the lateral component (VC2Y) of the first corrected airspeed (VC1) in the following manners: VC2X=K1*VC1X+K2*APC+N1VC2Y=K3*VC1Y+N2 in which second calculation functions, VC2X and VC2Y are the respective values of the longitudinal component and of the lateral component of the second corrected airspeed (VC2), K1, K2, and K3 are constants having respective values identified by a calibration operation in test flight for the second calculation functions, APC is the current collective pitch angle of the blades of the main rotor, and N1 and N2 are predefined summing values depending on the looked-for pertinence of the measurement of the true airspeed of the rotorcraft; and using lowpass filtering to apply data filtering to the individual values of the longitudinal component (VC2X) and of the lateral component (VC2Y) of the second corrected airspeed (VC2). 12. A method according to claim 4, wherein in hovering flight and in low speed flight of the rotorcraft, the true airspeed of the rotorcraft as displayed on the screen is the airspeed calculated after applying the data filtering. 13. A method according to claim 1, wherein the measurements supplied by the tail fin airspeed sensor are corrected by taking account of a plurality of the airspeed thresholds comprising at least: a first airspeed threshold associated with the rotorcraft flying at low speeds, with a first mode of correcting the measurements supplied by the tail fin airspeed sensor being applied when the rotorcraft is flying at an airspeed lower than or equal to the first airspeed threshold; anda second airspeed threshold associated with the rotorcraft flying at transitional airspeeds between low airspeeds and high airspeeds of the rotorcraft, a second mode of correcting the measurements supplied by the tail fin airspeed sensor being applied when the rotorcraft is flying at an airspeed higher than the first airspeed threshold and lower than or equal to the second airspeed threshold. 14. A method according to claim 13, wherein the second mode of correcting comprises an additional operation of correcting the measurements supplied by the tail fin airspeed sensor by using affine third calculation functions taking account of a correction parameter relating to additional measurements supplied by an auxiliary airspeed sensor installed on board the rotorcraft at a location that is as well separated as possible from the air stream produced by the wash of the main rotor. 15. A method according to claim 14, wherein the third calculation functions individually identify a longitudinal component (VC3X) and a lateral component (VC3Y) of a third corrected airspeed (VC3) in the following manners: VC3X=K4*VC2X+(1-K5)*VX VC3Y=K6*VC2X+(1-K7)*VY in which third calculation functions, VC3X and VC3Y are the respective values of the longitudinal component and of the lateral component of the third corrected airspeed (VC3), K4, K5, K6, and K7 are constants having respective values that are identified by a calibration operation in test flight for the third calculation functions, and VX and VY are the respective values of the longitudinal component and of the lateral component of the speed of the air stream measured by the auxiliary airspeed sensor. 16. A method according to claim 15, wherein when the rotorcraft is flying at transitional airspeeds, the true airspeed of the rotorcraft as displayed by the screen is the third corrected airspeed (VC3) corrected by a data filter applied individually to the longitudinal component (VC3X) and to the lateral component (VC3Y) of the third corrected airspeed (VC3). 17. A method according to claim 13, wherein when the rotorcraft is flying at high speed at an airspeed higher than the second airspeed threshold, the measurements supplied by the auxiliary airspeed sensor are used to display the true airspeed of the rotorcraft. 18. A rotorcraft having an airspeed indicator installation for performing a method according to claim 1, the airspeed indicator installation including at least one omnidirectional airspeed sensor, calculation means for deducing the true airspeed of the rotorcraft by making use of the measurements supplied by at least one omnidirectional airspeed sensor, and a display screen for displaying the true airspeed of the rotorcraft as deduced by the calculation means, wherein the at least one omnidirectional airspeed sensor, referred to as the “tail fin airspeed sensor”, is installed at the top of a tail fin of the rotorcraft. 19. A rotorcraft according to claim 18, wherein the calculation means comprise comparator means for comparing the airspeed of the rotorcraft supplied by the tail fin airspeed sensor with at least one predefined airspeed threshold, the calculation means incorporating a correction rule suitable for correcting the measurements supplied by the tail fin airspeed sensor as a function of effects produced by the rotation of at least a main rotor of the rotorcraft on the speed characteristics of the air stream measured by the tail fin airspeed sensor. 20. A rotorcraft according to claim 18, wherein the tail fin airspeed sensor is more particularly installed at the top of a tail fin of the rotorcraft extending upwards from a fairing surrounding a tail rotor of the rotorcraft in the general plane of the rotor disk of the tail rotor. 21. A rotorcraft according to claim 18, wherein the tail fin airspeed sensor is provided at its base with a shield for protecting it from the air stream flowing along the tail fin. 22. A rotorcraft according to claim 18, wherein the rotorcraft has an auxiliary airspeed sensor providing the calculation means with an additional measurement of the true airspeed of the rotorcraft together with the measurements supplied by the tail fin airspeed sensor.
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이 특허에 인용된 특허 (4)
Arethens J. P. (Valence FRX) Goumier-Beraud P. (Valence FRX), Method and device for determining the speed of a helicopter with respect to the air.
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