Rotorcraft having a stabilizer device

Abstract

A rotorcraft having at least one stabilizer device of the tail plane and/or of the tail fin type. At least one stabilizer device is a variable wing area stabilizer device comprising an airfoil member provided with a stationary airfoil surface and a movable airfoil surface. A control system is connected to a mover system for moving the movable airfoil surface in translation between a refracted position for occupying when the rotorcraft has a forward speed less than a first speed threshold, and an extended position for occupying when the rotorcraft has a forward air speed greater than a second speed threshold greater than the first speed threshold.

Claims

1. A rotorcraft having an airframe extending longitudinally from a nose to a rear zone, the rotorcraft comprising at least one main lift rotor and at least one tail rotor for controlling yaw movement and arranged in the rear zone, the rotorcraft including at least one stabilizer device arranged in the rear zone, each stabilizer device being selected from a list comprising a tail plane for stabilizing the rotorcraft in pitching and a tail fin for stabilizing the rotorcraft in yaw, at least one of the stabilizer devices being a variable wing area stabilizer device , each variable wing area stabilizer device comprising an airfoil member having a stationary airfoil surface that is stationary relative to the airframe, the airfoil member having a movable airfoil surface that is movable relative to the stationary airfoil surface, wherein the movable airfoil surface is movable at least in translation relative to the stationary airfoil surface, the rotorcraft comprising: a mover system for moving the movable airfoil surface at least in translation relative to the stationary airfoil surface from a retracted position in which a reference chord of the airfoil member is at a minimum, to an extended position in which the reference chord of the airfoil member is at a maximum; and a control system connected to the mover system to position the movable airfoil surface in the retracted position when the rotorcraft has a forward speed less than a first speed threshold, and in an extended position when the rotorcraft has a forward speed greater than a second speed threshold greater than the first speed threshold.

2. A rotorcraft according to claim 1, wherein at least two stabilizer devices are variable wing area stabilizer devices, the variable wing area stabilizer devices having a control system in common.

3. A rotorcraft according to claim 1, wherein at least two stabilizer devices are variable wing area stabilizer devices, the variable wing area stabilizer devices having a mover system in common.

4. A rotorcraft according to claim 1, wherein the mover system is a wormscrew system provided with a motor, a wormscrew, and at least one nut engaged on the wormscrew.

5. A rotorcraft according to claim 4, wherein the wormscrew is driven in rotation by the motor, the nut being fastened to a movable airfoil surface and being prevented from moving in rotation relative to the movable airfoil surface.

6. A rotorcraft according to claim 1, wherein the mover system comprises a jack.

7. A rotorcraft according to claim 1, wherein the airframe includes a tail boom carrying the variable wing area stabilizer device, and the mover system is arranged at least in part in the tail boom.

8. A rotorcraft according to claim 1, wherein the control system includes a computer, the computer being connected to a system for measuring the forward speed of the rotorcraft and to the mover system.

9. A rotorcraft according to claim 8, wherein the computer includes a relationship for degrading control of the mover system so as to position the movable airfoil surface in the extended position in the event of the system for measuring forward air speed malfunctioning.

10. A rotorcraft according to claim 8, wherein the system for measuring the forward air speed comprises an air speed measurement device enabling an indicated air speed to be measured.

11. A rotorcraft according to claim 8, wherein the system for measuring forward speed comprises a measurement sensor for measuring a position of at least one flight control of the rotorcraft.

12. A rotorcraft according to claim 1, wherein the control system includes manual control means operable by a pilot, the manual control means being connected to the mover system.

13. A rotorcraft according to claim 1, wherein the stationary airfoil surface includes a housing opening out to a trailing edge of the stationary airfoil surface, the movable airfoil surface being housed at least in part in the housing when in the refracted position.

14. A rotorcraft according to claim 13, wherein the movable airfoil surface is housed at least in part in the housing in the retracted position, with the reference chord of the airfoil member being equal to the reference chord of the stationary airfoil surface when the movable airfoil surface is in the retracted position.

15. A rotorcraft according to claim 1, wherein the movable airfoil surface, when in the extended position, lies in continuity with the stationary airfoil surface in the forward direction of the rotorcraft.

16. A rotorcraft according to claim 13, wherein, when the rotorcraft has a forward speed less than the first speed threshold, an air stream coming from a rotor impacts against a face of the stationary airfoil surface, and the housing is masked by the face facing the air stream.

17. A rotorcraft according to claim 1, wherein the movable airfoil surface is movable both in rotation and in translation relative to the stationary airfoil surface, the mover system moving the movable airfoil surface both in rotation and in translation relative to the stationary airfoil surface from a retracted position in which a reference chord of the airfoil member is at a minimum to an extended position in which the reference chord of the airfoil member is at a maximum.

18. A rotorcraft according to claim 1, wherein the movable airfoil surface is movable in translation relative to the stationary airfoil surface, the mover system moving the movable airfoil surface in translation relative to the stationary airfoil surface from a retracted position in which a reference chord of the airfoil member is at a minimum to an extended position in which the reference chord of the airfoil member is at a maximum.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail from the context of the following description of examples given by way of illustration and with reference to the accompanying figures, in which:

(2) FIG. 1 is a diagrammatic plan view of a rotorcraft having a tail plane with a movable airfoil surface in a retracted position;

(3) FIG. 2 is a diagrammatic view of an airfoil member having a movable airfoil surface in the refracted position;

(4) FIG. 3 is a diagrammatic view of an airfoil member having a movable airfoil surface in an extended position;

(5) FIG. 4 is a diagram explaining the threshold beyond which the movable airfoil surface extends;

(6) FIG. 5 is a diagrammatic plan view of a rotorcraft having a tail plane with a movable airfoil surface in the extended position;

(7) FIG. 6 is a diagrammatic plan view of a rotorcraft having a tail fin including a movable airfoil surface in a retracted position;

(8) FIG. 7 is a diagrammatic side view of a rotorcraft having a tail fin including a movable airfoil surface in the retracted position;

(9) FIG. 8 is a diagrammatic plan view of a rotorcraft having a tail fin including a movable airfoil surface in an extended position;

(10) FIG. 9 is a diagrammatic side view of a rotorcraft having a tail fin including a movable airfoil surface in the extended position;

(11) FIG. 10 is a diagrammatic plan view of a rotorcraft having a tail fin and a tail plane, each including a movable airfoil surface in a retracted position;

(12) FIG. 11 is a diagrammatic plan view of a rotorcraft having a tail fin and a tail plane, each including a movable airfoil surface in an extended position; and

(13) FIG. 12 is a diagrammatic view of an airfoil member having a movable airfoil surface that is movable in rotation and in translation.

DETAILED DESCRIPTION OF THE INVENTION

(14) Elements present in more than one of the figures are given the same references in each of them.

(15) It should be observed that three mutually orthogonal directions X, Y, and Z are shown in some of the figures.

(16) The first direction X is said to be longitudinal. The term longitudinal relates to any direction parallel to the first direction X.

(17) The second direction Y is said to be transverse. The term transverse relates to any direction parallel to the second direction Y.

(18) Finally, the third direction Z is said to be in elevation. The term in elevation relates to any direction parallel to the third direction Z.

(19) FIG. 1 shows a rotorcraft 1 of the invention.

(20) Whatever the embodiment, the rotorcraft comprises an airframe 2. The airframe 2 extends longitudinally from a nose 4 to a rear zone 5. The rear zone 5 is carried by a tail boom 3 of the airframe. Such a rear zone 5 is commonly referred to as a tail by the person skilled in the art.

(21) The rotorcraft 1 has at least one main rotor 6 for providing lift. The main rotor 6 in FIG. 1 is arranged above the airframe 2. In addition, the main rotor 6 is provided with a plurality of blades 7.

(22) A pilot can control the movement of the rotorcraft in conventional manner by varying the collective pitch and the cyclic pitch of the blades 7 by means of flight controls 58. These flight controls may comprise a cyclic pitch control for the blades of the main rotor and a collective pitch control for the blades of the main rotor.

(23) In addition, the rotorcraft is provided with a tail rotor 8 enabling the pilot to control movement of the rotorcraft in yaw. For example, pedals enable the pitch of blades 9 of the tail rotor 8 to be controlled.

(24) Under such circumstances, the tail rotor is arranged on the tail 5 of the rotorcraft.

(25) Furthermore, the rotorcraft 1 has at least one stabilizer device 10 arranged at the tail 5, each stabilizer device 10 being selected from a list comprising a tail plane 15 for stabilizing the rotorcraft 1 in pitching and a tail fin 20 for stabilizing the rotorcraft 1 in yaw.

(26) In the example of FIG. 1, the rotorcraft 1 has a tail boom carrying a tail plane 15 and a tail fin 20, the tail rotor 8 being carried by the tail fin 20.

(27) The tail plane shown has an airfoil member crossing the tail transversely. Nevertheless, other configurations could be envisaged. Thus, the tail plane could comprise a single airfoil member extending on one side only of the rotorcraft, or it could comprise a plurality of airfoil members each extending transversely on at least one side of the rotorcraft.

(28) Furthermore, at least one stabilizer device 10 is a stabilizer device of variable wing area 11.

(29) FIGS. 1 and 5 show a rotorcraft having a stabilizer device of variable wing area 11 of the tail-plane type. FIGS. 6 to 9 show a rotorcraft having a stabilizer device of variable wing area 11 of tail-fin type. FIGS. 10 and 11 show a rotorcraft having a stabilizer device of variable wing area 11 of tail-fin type and a stabilizer device of variable wing area 11 of tail-plane type.

(30) Independently of the variant and with reference to FIG. 2, a variable wing area stabilizer device 11 comprises an airfoil member 30.

(31) The airfoil member 30 is provided with an airfoil surface 31 secured to the rotorcraft airframe. Under such circumstances, this airfoil surface is said to be stationary airfoil surface 31.

(32) In addition, the airfoil member 30 is provided with an airfoil surface 35 that is movable relative to the rotorcraft airframe and to the associated stationary airfoil surface 31, at least in translation. Under such circumstances, the airfoil surface is said to be movable airfoil surface 35.

(33) Thus, the movable airfoil surface may be moved in translation in particular between a refracted position POS1 as shown in FIG. 2 and an extended position POS2 as shown in FIG. 3.

(34) The movable airfoil surface thus presents a flap of the airfoil member that is movable in translation and possibly, in an alternative, in rotation.

(35) With reference to FIG. 2, the stationary airfoil surface 31 of an airfoil member then defines a housing 70 for receiving the movable airfoil surface 35 of said airfoil member 30 at least in part, when in the retracted position.

(36) This housing 70 leads to the trailing edge 33 of the stationary airfoil surface 31.

(37) For example, the housing is inscribed between the suction side surface and the pressure side surface of the stationary airfoil surface.

(38) In the variant of FIG. 2, the housing 70 is defined in part by a single face of the stationary airfoil surface. In particular, the housing 70 is defined by the face of the stationary airfoil surface that is opposite from the face 34 that is struck by a stream of air 100 coming from a rotor 6, 8 of the rotorcraft.

(39) The housing 70 is then masked from such a stream of air 100 when said rotorcraft 1 has a forward speed that is below a first speed threshold 110.

(40) In the retracted position POST, the movable airfoil surface 35 is advantageously housed completely in the housing 70. The reference chord 90 of the airfoil member 30 is then equal to the reference chord 91 of the stationary airfoil surface 31.

(41) With reference to FIG. 3, the movable airfoil surface 35 is shown in contrast extending the stationary airfoil surface 31 in the travel direction X of the rotorcraft 1 in its extended position POS2. A slot 38 may optionally separate the leading edge 36 of the movable airfoil surface from the trailing edge 33 of the stationary airfoil surface.

(42) In order to give the movable airfoil surface 35 a degree of freedom to move in translation along a longitudinal direction X, the stabilizer device of variable wing area includes a mover system 40 for moving the movable airfoil surface 35 at least in translation relative to the stationary airfoil surface 31.

(43) In the variant of FIG. 3, the mover system 40 may comprise a jack type actuator 45. The jack 45 may be an electric, hydraulic, or pneumatic jack.

(44) In the variant of FIG. 1, the mover system 40 may comprise a wormscrew system type actuator. Such a wormscrew system is provided with a motor 41, such as an electric, hydraulic, or pneumatic motor, for example. In addition, the wormscrew system is provided with a wormscrew 42 and a nut 43 through which the wormscrew 42 passes.

(45) Under such circumstances, the nut may be secured to a movable airfoil surface 35 so as to be provided with at least a degree of freedom to move in translation, eventually a single degree of freedom to move in translation.

(46) Consequently, the motor drives the wormscrew 42 in rotation. The nut 43 then slides along the wormscrew, thereby causing the associated movable airfoil surface to move at least in translation.

(47) Independently of the nature of the actuator of the mover system, the actuator is advantageously arranged at least in part in the tail boom 3.

(48) In addition, the mover system may include at least one slideway 44 that guides the movement in translation of the movable airfoil surface.

(49) In an alternative, the movable airfoil surface 35 is movable in translation only.

(50) Nevertheless, in the alternative of FIG. 12, the movable airfoil surface 35 is movable both in translation and in rotation. For example, the movable airfoil surface 35 has studs 46 that slide in curved slideways 44. Under such circumstances, a movement in translation of the actuator 45 of the mover system leads to a movement both in rotation and in translation of the movable airfoil surface 35.

(51) Furthermore, and with reference to FIG. 1, the stabilizer device of variable wing area includes a control system 50 connected to the mover system 40.

(52) The control system 50 controls the mover system so as to position the movable airfoil surface 35 in the retracted position POST when the rotorcraft has a forward speed IAS less than a first speed threshold 110, and in an extended position when the rotorcraft 1 has a forward speed greater than a second speed threshold 120 that is greater than the first speed threshold 110.

(53) This forward speed may be the indicated air speed (IAS) of the rotorcraft.

(54) FIG. 4 shows a diagram presenting the forward speed of the aircraft plotted along the abscissa axis in knots (kt) and the travel of the movable airfoil surface 35 of an airfoil member plotted up the ordinate axis in millimeters.

(55) Below the first speed threshold 110, the movable airfoil surface 35 is in the retracted position POS1. Above the second speed threshold 120, the movable airfoil surface 35 is in the extended position POS2.

(56) Between the retracted position POS1 and the extended position POS2, the movement in translation of the movable airfoil surface 35 is determined, by way of example, by a relationship that is a function of the forward speed of the rotorcraft. Such a function may be an affine function.

(57) With reference to FIG. 1, the control system 50 may include a computer 51 connected to the mover system 40.

(58) Furthermore, the computer 51 is connected to a system 55 for measuring the forward speed of the rotorcraft 1 in order to determine the position in which the movable airfoil surface should be found.

(59) Under such circumstances, the system 55 for measuring forward air speed may comprise an air speed measurement device 56 of conventional type serving to measure an indicated air speed IAS.

(60) Optionally, the system 55 for measuring the forward speed comprises a measurement sensor 57 for measuring a position of at least one flight control 58 of the rotorcraft 1.

(61) In the event of the air speed measurement device 56 malfunctioning, the computer may use the measurement sensor 57 for evaluating the forward speed of the rotorcraft. For example, the computer can estimate the forward speed as a function of the position of the device for controlling the cyclic pitch of the blades of the main rotor.

(62) Optionally, the computer 51 may also include a degraded piloting relationship for telling the mover system 40 to place the movable airfoil surface 35 in the extended position POS2 in the event of the system 55 for measuring forward speed failing.

(63) The control system 50 may also include at least one pilot-operable manual control means 60. The manual control means 60 are connected to the mover system 40 either directly or indirectly via the computer.

(64) Under such circumstances, the actuator of a mover system can be controlled automatically or manually. For example, the mover system may be controlled automatically so long as the manual control means are not operated.

(65) FIGS. 1 and 5 explain the operation of a rotorcraft including a variable wing area stabilizer device 11 of the tail-plane type.

(66) With reference to FIG. 1, the tail plane 15 is provided with a stationary airfoil surface 31 and with a movable airfoil surface 35.

(67) At low forward speed of the rotorcraft, i.e. when the rotorcraft is traveling at a forward speed less than the first speed threshold 110, the movable airfoil surface 35 is in the retracted position. The reference chord of the tail plane is then minimized, thereby tending to minimize the attitude hump phenomenon.

(68) With reference to FIG. 5, when the rotorcraft is traveling at a forward speed greater than the first speed threshold 110, the movable airfoil surface 35 is moved away from the stationary airfoil surface longitudinally, either automatically or manually, so as to increase the reference chord of the tail plane.

(69) When the rotorcraft is traveling at a forward speed greater than the second threshold speed 120, the movable airfoil surface 35 is in the extended position POS2, with the reference chord of the tail plane then being maximized.

(70) FIGS. 6 to 9 show a rotorcraft having a variable wing surface stabilizer device 11 of the tail-fin type.

(71) With reference to FIGS. 6 and 7, the tail fin 20 has a stationary airfoil surface 31 and a movable airfoil surface 35.

(72) At a low forward speed of the rotorcraft, i.e. when the rotorcraft is traveling at a forward speed lower than the first speed threshold 110, the movable airfoil surface 35 is in the retracted position. The reference chord of the tail fin is then minimized, thereby tending to minimize the fin lock phenomenon.

(73) With reference to FIGS. 8 and 9, when the rotorcraft is traveling at a forward speed greater than the first speed threshold 110, the movable airfoil surface 35 is moved away from the stationary airfoil surface in the longitudinal direction, either automatically or manually, in order to increase the reference chord of the tail fin.

(74) When the rotorcraft is traveling at a forward speed greater than the second speed threshold 120, the movable airfoil surface 35 is in the extended position POS2, the reference chord of the tail fin then being maximized.

(75) FIGS. 10 and 11 show a rotorcraft having a variable wing area stabilizer device 11 of the tail-fin type and a variable wing area stabilizer device 11 of the tail-plane type.

(76) Optionally, the variable wing area stabilizer devices 11 have a common control system 50 and a common mover system 40.

(77) Naturally, the present invention may be subjected to numerous variations as to its implementation. Although several embodiments are described, it will readily be understood that it is not conceivable to identify exhaustively all possible embodiments. It is naturally possible to envisage replacing any of the means described by equivalent means without going beyond the ambit of the present invention.