EP0869901A1 - Systeme de regulation et de stabilisation automatique du mouvement de giration d'un aeronef a voilure tournante - Google Patents

Systeme de regulation et de stabilisation automatique du mouvement de giration d'un aeronef a voilure tournante

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Publication number
EP0869901A1
EP0869901A1 EP96928019A EP96928019A EP0869901A1 EP 0869901 A1 EP0869901 A1 EP 0869901A1 EP 96928019 A EP96928019 A EP 96928019A EP 96928019 A EP96928019 A EP 96928019A EP 0869901 A1 EP0869901 A1 EP 0869901A1
Authority
EP
European Patent Office
Prior art keywords
gyro
rotor
thrust
rotation
aircraft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP96928019A
Other languages
German (de)
English (en)
Other versions
EP0869901A4 (fr
Inventor
Paul E. Arlton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ARLTON, PAUL E.
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0869901A1 publication Critical patent/EP0869901A1/fr
Publication of EP0869901A4 publication Critical patent/EP0869901A4/fr
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/82—Rotorcraft; Rotors peculiar thereto characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft

Definitions

  • Patent Application No. 60/001558 filed July 27, 1995 and Provisional Patent Application No. 60/007079, filed October 24, 1995.
  • This invention relates to flight-direction control systems for both model and full-size rotary wing aircraft, and particularly to a helicopter tail rotor and a helicopter yaw (right-left heading) stabilizer system. More particularly, the invention relates to a gyroscope mounted on a helicopter tail rotor assembly and configured to cause the tail rotor to produce a yaw moment or torque stabilizing the helicopter in flight so that the helicopter is able to fly in a direction (heading) selected by the pilot, whether the pilot is onboard a full-size helicopter or commanding a model helicopter by remote control. While this invention can be applied to many types of aircraft, both full-size and models, it will be described herein primarily for use on helicopters for clarity.
  • Helicopters are flying machines having the ability to hover and fly forwards, backwards, and sideways. This agility stems from the multiple capabilities of the main rotor system. Since the invention of helicopters in the 1930's, considerable effort has been spent advancing helicopter technology, with a substantial percentage of that effort concentrated on main rotor systems. Less effort has been applied to develop better tail rotor systems.
  • All helicopters having one main rotor require some sort of yaw stabilizer or yaw-control system in order to counteract torque generated by the main rotor during flight so as to maintain directional control of the helicopter.
  • the main rotor system of a helicopter is typically mounted to lie above the helicopter cabin and rotate about a vertical axis extending through the cabin so as to provide a controllable motive force for lifting the helicopter into the air and propelling the helicopter in any direction.
  • a main rotor system typically includes rotor blades for producing aerodynamic lift and other blades that act to augment control and stability of the main rotor.
  • a main rotor system also includes a swashplate assembly and various linkages for transmitting pilot control commands to the rotating rotor blades.
  • yaw-control devices have been developed for helicopters to counteract torque generated by main rotor systems or changing wind gusts. These yaw- control devices include, for example, blown tail booms and shrouded fans. Nevertheless, traditional helicopter tail rotor and yaw-control systems have remained essentially unchanged for twenty-five years.
  • helicopter pilots In general, maintaining the stable yaw orientation (right-left heading) of a helicopter in hover or low-speed flight can be difficult for a helicopter pilot.
  • helicopter pilots To counterbalance the constantly changing torques on the helicopter fuselage produced by the main rotor blades and atmospheric conditions such as lateral wind gusts, helicopter pilots must continually manipulate the yaw controls of their aircraft. This is especially true for pilots of model helicopters because of the small size and low mass of model helicopters, and the resulting tendency of a model helicopter to react rapidly to disturbances.
  • Other types of aircraft such as tilt-rotor aircraft (which operate at some times like an airplane and at other times like a helicopter) , can have similar control problems along a different rotation axis (such as the roll axis) .
  • helicopter yaw-control systems for controlling a helicopter tail rotor to maintain directional control of the helicopter in flight use gyroscopes to sense the constantly changing torques applied to the helicopter in flight and use various mechanisms to adjust the pitch of the tail rotor blades in response to movement of the gyroscope onboard the helicopter.
  • These helicopter yaw- control systems are referred to generally as gyro- stabilizer systems and can be classified, for example, as electronic-, single rotor-, and dual rotor-gyro-stabilizer systems. A discussion of each of these three gyro- stabilizer systems is provided below.
  • Electronic gyro-stabilizer systems are now widely available for use in controlling the tail rotor of both model and full-size helicopters to help pilots cope with yaw instability of a helicopter during flight. These electronic systems, however, are typically heavy and expensive. On model helicopters, they often require an additional or expanded electric power supply to power the requisite amplifier electronics and to drive the electro ⁇ mechanical gyroscope associated with an electronic gyro- stabilizer system. On man-carrying helicopters, electronic gyro-stabilizer systems are practical only in helicopters having control systems with electric or hydraulic servo actuators. The pilots of small man-carrying helicopters, who typically must actuate the controls of their aircraft directly, cannot take advantage of these electronic gyro- stabilizer systems.
  • the gyroscope that lies onboard a helicopter and senses the yaw motion of the helicopter should be driven directly from the power produced by an engine or power plant of the helicopter instead of by an auxiliary power supply (such as a battery) . It should also accommodate a variety of helicopter tail rotor configurations to be useful on as many different types of aircraft as possible.
  • the center of mass of the tail rotor in Burkam's system is unavoidably offset from the tail rotor pivot axis. In operation, this offset center of mass leads to a vertical swinging motion of the entire tail rotor that is operationally and structurally unsound.
  • a spring or other device is required to compensate for the weight of the tail rotor assembly to keep the tail rotor from drooping downward.
  • Vertical accelerations of the aircraft such as those generated during climbing or descending maneuvers, will cause the tail rotor to swing upward or downward. This swinging motion will operate exactly like a gyro input to the control system, and will cause the aircraft to yaw unexpectedly.
  • single-rotor systems in accordance with the present invention may be configured to tilt about an axis substantially coplanar with the gyro rotor without significant swinging motion and subsequent vertical displacement.
  • Tilt of the entire tail rotor can also unfavorably redirect the thrust force of the rotor in unwanted directions, and can cause unwanted rotation of the aircraft about a shifting axis of rotation.
  • the gyroscopic mechanism in any type of mechanical aircraft yaw control and stabilization system must tilt enough to displace the linkages in the system to actuate effectively the pitch controls of the thrust-producing part (e.g., tail rotor blades) of the system. In practice, this tilt angle typically falls in the range of 10 to 20 degrees, and can be associated with the general concept of "bandwidth" in control systems.
  • dual-rotor gyro-stabilizer systems separate the primary thrust-producing part from the yaw- stabilizing part. Since the primary thrust-producing rotor need not tilt, the thrust it generates acts only in the desired direction.
  • a dual rotor gyro-stabilizer system is described in U.S. Patent No. 3,004,736 to Culver, and another is discussed on pages 41, 45, and 76-79 of the March 1973 issue of American Aircraft Modeler magazine (originally located at 733 15th Street N.W., Washington, D.C. 20005).
  • pilot control commands must physically override (tilt) the gyroscopic mechanism in order to control the directional heading of the aircraft.
  • control inputs from the pilot were not combined with aircraft yaw stabilizing inputs from the gyroscopic mechanism so that the aircraft yaw control and stabilizing functions could operate independently.
  • a device for stabilizing rotational motion of a rotary wing aircraft about an aircraft axis of rotation is provided.
  • the rotary wing aircraft includes an aircraft body.
  • the device includes a thrust-producing mechanism for generating a thrust force along a thrust axis that is substantially perpendicular to the aircraft axis of rotation and a thrust-varying mechanism for permitting a pilot to remotely control the thrust-producing mechanism to vary the magnitude of the thrust force produced by the thrust- producing mechanism.
  • the device further includes a gyro rotor mechanism for automatically controlling the thrust- producing mechanism to vary the magnitude of the thrust force produced by the thrust-producing mechanism to oppose rotational motion of the rotary wing aircraft about the aircraft axis of rotation during flight.
  • the gyro rotor mechanism is mounted to the aircraft body to maintain a fixed position relative to the thrust-producing mechanism.
  • the device further includes a mechanism for independently connecting each of the gyro rotor mechanism and thrust- varying mechanism to the thrust-producing mechanism so that each of the thrust-varying mechanism and the gyro rotor mechanism operates independently to vary the thrust force generated by the thrust-producing mechanism and so that the gyro rotor remains in a fixed position relative to the thrust-producing mechanism when the pilot operates the thrust-varying mechanism to vary the magnitude of the thrust force produced by the thrust-producing mechanism.
  • the thrust-producing mechanism is a tail rotor configured to rotate about a common axis of rotation with the gyro rotor mechanism.
  • the gyro rotor mechanism is mounted on the helicopter body so that the gyro rotor mechanism is fixed relative to the tail rotor along the common axis of rotation. Thus, the gyro rotor mechanism does not move linearly along the common axis of rotation when the pilot changes the magnitude of the thrust force produced by the thrust-producing mechanism.
  • a system for controlling and automatically stabilizing the rotational motion of a rotary wing aircraft in flight and particularly for stabilizing the yaw motion of a helicopter in flight.
  • a system comprises a primary thrust-producing part such as a helicopter tail rotor that can direct a thrust force along an axis offset from, and substantially perpendicular to, the rotation axis of the aircraft and a yaw-stabilizing part.
  • the tail rotor generally includes cambered blades which are aerodynamically and centrifugally balanced and suited for use with the yaw-stabilizing part.
  • the thrust-producing part is controlled by inputs from a pilot control part if the aircraft has a pilot control system and from a gyroscope included in the yaw-stabilizing part.
  • the yaw-stabilizing part senses rotational or yaw motion of the aircraft and actuates the thrust- producing part to slow or stop rotational or yaw motion of the aircraft.
  • a centrifugal restoring mechanism included in the system restores the yaw-stabilizing part to a nominal condition in preparation for any subsequent aircraft rotation or yaw.
  • the yaw-stabilizing part may be adapted to produce a thrust force to augment the thrust force produced by the thrust-producing part.
  • the thrust-producing and yaw-stabilizing parts are mounted on an appendage of the aircraft and may be separate mechanisms located in mutual proximity to one another, separate mechanisms located at a remote distance from each other and connected through linkage means or electronic means, or a single combined mechanism performing both thrust-producing and yaw-stabilizing functions.
  • the present invention may be applied in a wide variety of configurations to suit various aircraft types and configurations.
  • the thrust-producing means includes a thrust-producing rotor having a plurality of rotor blades extending radially from a rotor shaft.
  • the gyro rotor means is a weighted disk or plurality of weighted arms extending radially from a gyro hub. Rotation of the aircraft causes the gyro rotor means to tilt and to actuate linkages attached to the thrust-producing rotor thereby adjusting the amount of thrust created by the rotor and automatically stabilizing the aircraft.
  • the gyro rotor rotates in a gyro rotor plane of rotation and the pivot axis is generally coplanar or nearly coplanar with the gyro rotor plane of rotation to minimize swinging motion of the gyro rotor means.
  • the gyro rotor means may, in some embodi ents, be adapted to produce a thrust force to augment the thrust generated by the thrust-producing means, or may be combined into one mechanism with the thrust- producing means.
  • Several types of drive linkages including, for instance, universal joints, sliders, and follower linkages, are provided to drive the gyro rotor means as it may tilt in response to rotation or yaw of the aircraft in flight.
  • the gyro rotor means is restored to its nominal orientation by aerodynamic forces (such as those produced through cyclically pitching paddles or blades) , rotational or gyroscopic forces (such as through flapping action or "coning" of the weighted arms) , and/or by mechanical forces (such as through springs) .
  • the present invention is adapted for use on a helicopter and includes a gyro rotor having a number of weighted arms or paddles extending radially from a gyro rotor hub, and driven by the power produced by the engine of the helicopter.
  • the gyro rotor is mounted to pivot about a gyro pivot axis which is substantially perpendicular to the main rotor axis and to move linkages including push-pull rods, sliders, and mixing arms that actuate to the pitch-change elements of the tail rotor blades.
  • Yaw motion of the helicopter causes the gyro rotor to pivot or tilt about the gyro pivot axis thereby displacing the gyro rotor linkages and changing the pitch of the tail rotor blades. This change in pitch alters the thrust produced by the tail rotor to oppose the original yaw motion.
  • the present invention provides a restoring mechanism that restores the gyro rotor to its nominal orientation after the gyro rotor has pivoted or tilted in response to yaw motion of the helicopter.
  • the gyro rotor includes a plurality of gyro arms pivotably connected at their base to a supporting roechanism.
  • a weight is connected to each of the gyro arms so that centrifugal forces acting on the gyro arms orients the gyro arms radially from the supporting mechanism.
  • the gyro rotor is adapted to produce a thrust force that augments the thrust force created by the tail rotor.
  • Other configurations in accordance with the present invention combine the gyro rotor and the tail rotor into a single mechanism.
  • Each configuration or preferred embodiment in accordance with the present invention has certain advantages over the others (such as greater simplicity or greater thrust producing potential) , and selection of the appropriate configuration depends upon the specific application. It will be understood that the features of the various embodiments in accordance with the present invention may be recombined to form additional embodiments differing in appearance, but generally performing the same function.
  • the yaw-stabilizing part is not functionally affected by pilot control inputs.
  • Various means such as three-point mixing arms, are provided to combine the stabilization features of the gyroscope in the yaw-stabilizing part with control inputs from the pilot so that pilot control is not inhibited.
  • pilot control inputs may operate to move the gyro rotor linearly in space. Because such linear motion will not cause the gyroscope in the yaw-stabilizing part to tilt, these pilot inputs have no operational effect on the gyroscope. While the elements of the current invention will operate in applications in which pilot commands forcibly override the gyroscopic stabilization mechanism, independent control is more desirable and advantageous.
  • the gyro rotor is fixed relative to the fuselage of the helicopter.
  • the mounting structure for a gyro rotor having a fixed pivot axis may be more simply and solidly constructed (for a given weight) than the mounting structure for a gyro rotor that must both pivot and translate relative to the fuselage.
  • fixed mounting of the gyro rotor allows the gyro rotor to be more easily placed at different locations on the helicopter.
  • the present invention includes a gyro spindle that pivots in response to pivoting motion of the gyro arms due to yaw motion of the helicopter.
  • the gyro arms are directly connected to and supported by the gyro spindle.
  • the gyro arms are linked to the gyro spindle through gyro linkages so that pivotable movement of the gyro arms is transferred to the gyro spindle.
  • the gyro spindle doe ⁇ not support the gyro arms and thus the gyro spindle is not subjected to radial flight loads generated by the gyro arms and can be made of lighter construction. Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments which illustrate the best mode for carrying out the invention as presently perceived.
  • Fig. 1 is a perspective view of a representative helicopter including a tail assembly fitted with an improved yaw control and stabilization system in accordance with the present invention
  • Fig. 2 is an exploded perspective view of the tail boom and tail rotor gearbox mechanism of the helicopter illustrated in Fig. 1, showing components situated within the tail boom and tail rotor gear box;
  • Fig. 2a is an exploded perspective view of the gyroscopic mechanism of the helicopter illustrated in
  • Fig. 1 showing details of the gyro rotor, gyro spindle, gyro control linkage, and scissor-link drive means;
  • Figs. 3 through 7 illustrate in more detail first, second, and third embodiments of an improved yaw control and stabilization system of the present invention, each having a gyro rotor located outboard of a primary tail rotor and opposite the tail rotor gearbox;
  • Fig. 3 is an enlarged perspective view of the tail assembly of the helicopter illustrated in Fig. 1 fitted with the first embodiment of the improved yaw control and stabilization system of the present invention
  • Fig. 4 is a top plan view of the first embodiment which illustrates the general configuration of the tail rotor gearbox and primary tail rotor of the current invention for the first, second, and third embodiments shown in Figs. 3-7, with the vertical tail fin and all elements of the helicopter forward of the tail rotor gearbox removed for clarity;
  • Fig. 5 is a rear-end elevation view of the first embodiment which has a hollow tail rotor shaft, a gyro rotor appended to the end of a push-pull rod and translatable in response to pilot control commands, follower-link drive means in the form of scissor linkages driving the gyro rotor, and aerodynamic restoring means in the form of gyro paddles, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade- balancing weights, and all elements of the helicopter forward of the tail rotor gearbox removed for clarity;
  • Fig. 6 is a rear-end elevation view of a second embodiment which has a hollow tail rotor shaft, a gyro rotor appended to the end of a push-pull rod and translatable in response to pilot control commands, follower-link drive means in the form of drive bars driving the gyro rotor, and centrifugal restoring means in the form of weighted gyro arms, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade- balancing weights, and all elements of the helicopter forward of the tail rotor gearbox removed for clarity;
  • Fig. 7 is a rear-end elevation view of a third embodiment which has a hollow tail rotor shaft, a gyro rotor mounted to a slider and translatable in response to pilot control commands, follower-link drive means in the form of drive bars driving the gyro spindle, follower-link drive means driving the gyro rotor, and centrifugal restoring means in the form of weighted gyro arms, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the tail rotor gearbox removed for clarity; Figs.
  • FIG. 8 through 14 illustrate fourth through ninth embodiments of the improved yaw control and stabilization system of the present invention, each having a gyro rotor located between the primary tail rotor and the tail rotor gearbox;
  • FIG. 8 is a top plan view of the fourth embodiment, showing the general configuration of the tail rotor gearbox and primary tail rotor of the current invention for the fourth through ninth embodiments shown in Figs. 9 through 14, respectively, with elements of the gyro rotor mounting mechanism shown in cross-section, and with one end of the gyro pushrod, vertical tail fin, gyro rotor arms, and all elements of the helicopter forward of the tail rotor gearbox removed for clarity;
  • Fig. 9 is a rear-end elevation view of the fourth embodiment which has a hollow tail rotor shaft, a gyro rotor pivotably mounted to the gearbox, a three-point mixing arm for combining pilot control and gyro control inputs, universal drive means located at the center of the gyro rotor, and mechanical restoring means in the form of adjustable springs, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade- balancing weights and all elements of the helicopter forward of the tail rotor gearbox removed for clarity;
  • Fig. 10 is a rear-end elevation view of a fifth embodiment which has a hollow tail rotor shaft, a gyro rotor pivotably mounted to the gearbox, electronic means for combining pilot control and gyro control inputs, universal drive means located at the center of the gyro rotor, and mechanical restoring means in the form of adjustable springs, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade- balancing weights and all elements of the helicopter forward of the tail rotor gearbox removed for clarity;
  • Fig. 11 is a rear-end elevation view of a sixth embodiment which has a hollow tail rotor shaft, a thrust- producing gyro rotor pivotably mounted to the gearbox, universal drive means located at the center of the gyro rotor, a three-point mixing arm for combining pilot control and gyro control input ⁇ , and aerodynamic restoring means in the form of gyro rotor blades, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 12 is a rear-end elevation view of a seventh embodiment which has a hollow tail rotor shaft, a gyro rotor pivotably mounted to the gearbox on an offset pivot axis, a three-point mixing arm for combining pilot control and gyro control inputs, follower-link drive means in the form of scissor linkages driving the gyro rotor, and mechanical restoring means in the form of springs, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity; Fig.
  • FIG. 13 is a rear-end elevation view of an eighth embodiment which has a solid tail rotor shaft, a gyro rotor pivotably mounted to a slider and translatable in response to pilot control commands, follower-link drive means and mechanical restoring means in the form of semi-flexible drive bars, with one tail rotor blade shown in cross- section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 14 is a rear-end elevation view of a ninth embodiment which has a solid tail rotor shaft, a thrust- producing gyro rotor pivotably mounted to a slider and translatable in response to pilot control commands, three- point mixing arms for combining pilot control and gyro control inputs, follower-link drive mean ⁇ in the form of drive bars driving the gyro rotor, and aerodynamic restoring means in the form of gyro rotor blades, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity;
  • Figs. 15 through 23 illustrate tenth through seventeenth embodiments of the improved yaw control and stability system of the current invention, each having a gyro rotor located beside the tail rotor gearbox opposite the primary tail rotor, where;
  • Fig. 15 is a top plan view of a tenth embodiment which illustrates the general configuration of the gearbox and primary tail rotor of the current invention for the tenth through seventeenth embodiments shown in Figs. 16 through 23 respectively, with elements of the gyro rotor mounting mechanism shown in cross-section, and with the vertical tail fin, gyro rotor arms, and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 16 is a rear-end elevation view of the tenth embodiment which has a solid tail rotor shaft, a gyro rotor pivotably mounted to the gearbox, a three-point mixing arm for combining pilot control and gyro control inputs, universal drive means located at the center of the gyro rotor, and mechanical restoring means in the form of springs, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 17 is a rear-end elevation view of an eleventh embodiment which has a solid tail rotor shaft, a gyro rotor pivotably mounted to the gearbox, a three-point mixing arm for combining pilot control and gyro control inputs, follower-link drive means in the form of drive bars driving the gyro rotor, and mechanical restoring means in the form of springs, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade- balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 18 is a rear-end elevation view of a twelfth embodiment which ha ⁇ a solid tail rotor shaft, a gyro rotor pivotably mounted to the tail rotor ⁇ haft and pivotably con ⁇ trained by a tiltable gyro ⁇ pindle, a three-point mixing arm for combining pilot control and gyro control input ⁇ , follower-link drive mean ⁇ in the form of drive bars driving the gyro spindle, and centrifugal restoring means in the form of weighted gyro arms, with one tail rotor blade shown in cros ⁇ -section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity; Fig.
  • FIG. 18a is a rear-end elevation view of the embodiment shown in Fig. 18 with the gyro rotor reacting to a yaw motion of helicopter 10 showing representative operation of the flapping gyro arms, gyro spindle, and gyro control linkages; Fig.
  • FIG. 19 is a rear-end elevation view of a thirteenth embodiment which has a solid tail rotor shaft, a gyro rotor pivotably mounted to the gearbox, a three-point mixing arm for combining pilot control and gyro control inputs, follower-link drive means in the form of drive bars driving the gyro rotor, and centrifugal restoring means in the form of weighted gyro arms, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all elements of the helicopter forward of the gearbox removed for clarity; Fig.
  • Fig. 21 is a rear-end elevation view of a fifteenth embodiment which has a solid tail rotor shaft, a gyro rotor pivotably mounted to the gearbox about an off ⁇ et pivot axis, a three-point mixing arm for combining pilot control and gyro control input ⁇ , follower-link drive mean ⁇ and mechanical re ⁇ toring mean ⁇ in the form of semi-flexible drive bars driving the gyro rotor, with one tail rotor blade shown in cross-section, and with the vertical tail fin, blade-balancing weights, and all element ⁇ of the helicopter forward of the gearbox removed for clarity; Fig.
  • a rear-end elevation view of a sixteenth embodiment which has a ⁇ olid tail rotor ⁇ haft, a thru ⁇ t-producing gyro rotor pivotably mounted to the gearbox about an offset pivot axis, a three-point mixing arm for combining pilot control and gyro control input ⁇ , follower-link drive mean ⁇ in the form of drive bar ⁇ driving the gyro rotor, and aerodynamic re ⁇ toring means in the form of gyro rotor blades, with one tail rotor blade shown in cros ⁇ - ⁇ ection, and with the vertical tail fin, blade- balancing weight ⁇ , and all element ⁇ of the helicopter forward of the gearbox removed for clarity; and
  • Fig. 23 i ⁇ a rear-end elevation view of a seventeenth embodiment which has a solid tail rotor shaft, a gyro rotor pivotably mounted to a slider and translatable in response to pilot control commands, follower-link drive means in the form of drive bars driving the gyro rotor, and aerodynamic restoring means in the form of gyro paddles, with one tail rotor blade shown in cros ⁇ - ⁇ ection, and with the vertical tail fin, blade-balancing weight ⁇ , and all element ⁇ of the helicopter forward of the gearbox removed for clarity.
  • Figs. 24 through 28 illustrate five single-rotor embodiments of the improved yaw control and stability system of the pre ⁇ ent invention, each having a gyro rotor and tail rotor combined into a single mechanism, where;
  • Fig. 24 i ⁇ a rear-end elevation view of the fir ⁇ t single-rotor embodiment which has a hollow rotor shaft, a single thrust-producing gyro rotor pivotably mounted to the gearbox, a three-point mixing arm for combining pilot control and gyro control inputs, universal drive means located at the center of the gyro rotor, and aerodynamic restoring means in the form of cyclically-pitchable gyro rotor blades, with the vertical tail fin, blade balancing-weights and all element ⁇ of the helicopter forward of the gearbox removed for clarity;
  • Fig. 25 i ⁇ a rear-end elevation view of the second single-rotor embodiment which has a hollow rotor shaft, a single thrust-producing gyro rotor pivotably mounted to the gearbox, electronic means for combining pilot control and gyro control inputs in the form a linkage moveable with respect to an electronic sensor mounted to the gearbox, universal drive means located at the center of the gyro rotor, and aerodynamic restoring means in the form of cyclically-pitchable gyro rotor blades, with the vertical tail fin, blade balancing-weights and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 26 is a rear-end elevation view of the third single-rotor embodiment which has a hollow rotor shaft, a single thrust-producing gyro rotor operably mounted to the rotor shaft to flap about a flapping axis and pivotably constrained by a tiltable gyro spindle mounted to the gearbox, follower-link drive means in the form of drive bar ⁇ driving the gyro ⁇ pindle, and aerodynamic re ⁇ toring mean ⁇ in the form of cyclically-pitchable gyro rotor blade ⁇ , with the vertical tail fin, blade balancing-weight ⁇ and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig. 27 is a rear-end elevation view of the fourth single-rotor embodiment which has a hollow rotor shaft, a single thrust-producing gyro rotor appended to the end of a push-pull rod pas ⁇ ing through the ⁇ haft and tran ⁇ latable in re ⁇ pon ⁇ e to pilot control commands, follower-link drive means in the form of drive bars driving the gyro rotor, and aerodynamic restoring means in the form of cyclically-pitchable gyro rotor blades, with the vertical tail fin, blade balancing-weights and all elements of the helicopter forward of the gearbox removed for clarity;
  • Fig ⁇ . 28 and 29 illustrate universal drive means that may be advantageously employed with certain of the embodiment ⁇ of the current invention;
  • the present invention include ⁇ a gyro rotor mechanism mounted to the aircraft body to maintain a fixed position relative to the thrust-producing mechanism.
  • the thrust-producing mechanism is a tail rotor configured to rotate about a common axis of rotation with the gyro rotor mechanism.
  • the gyro rotor mechanism i ⁇ mounted on the aircraft body ⁇ o that the gyro rotor mechanism is fixed relative to the tail rotor along the common axis of rotation.
  • the gyro rotor mechanism does not move linearly along the common axis of rotation when the pilot changes the magnitude of the thrust force produced by the thrust-producing mechanism.
  • the pre ⁇ ent invention include ⁇ a gyro spindle that pivots in respon ⁇ e to pivoting motion of the gyro arm ⁇ due to yaw motion of the helicopter.
  • the gyro arm ⁇ are directly connected to end ⁇ upport the gyro spindle.
  • the gyro arm ⁇ are linked to the gyro ⁇ pindle through gyro linkages so that pivotable movement of the gyro arms is transferred to the gyro spindle.
  • the gyro spindle does not support the gyro arms and thus the gyro spindle is not subjected to radial flight loads generated by the gyro arm ⁇ and can be made of lighter con ⁇ truction.
  • the present invention also provides a restoring mechanism that restores the gyro rotor to its nominal orientation after the gyro rotor has pivoted or tilted in re ⁇ ponse to yaw motion of the helicopter.
  • the gyro rotor includes a plurality of gyro arms pivotably connected at their base to a supporting mechanism.
  • a weight is connected to each of the gyro arms so that centrifugal forces acting on the gyro arms orients the gyro arm ⁇ radially from the supporting mechanism.
  • the yaw-stabilizing part or gyro rotor mechanism is not functionally affected by pilot control inputs or the thru ⁇ t-varying mechanism.
  • Various means such as three- point mixing arm ⁇ , are provided to combine the stabilization features of the gyro ⁇ cope in the yaw- ⁇ tabilizing part with control input ⁇ from the pilot so that pilot control is not inhibited.
  • pilot control input ⁇ may operate to move the gyro rotor linearly in space. Because such linear motion will not cause the gyroscope in the yaw-stabilizing part to tilt, the ⁇ e pilot input ⁇ have no operational effect on the gyro ⁇ cope.
  • Tail rotor 2 is mounted at the end of a tail boom 16 as shown in Figs. 1 and 3.
  • both main rotor 1 and tail rotor 2 of helicopter 10 are driven by a power plant such as engine 3 usually located within the helicopter fu ⁇ elage (body) near the main rotor shaft (mostly hidden) .
  • a streamlined fuselage shell 4 covers the front of helicopter 10, but doe ⁇ not extend back to tail rotor 2. In alternative embodiment ⁇ , the fu ⁇ elage shell may extend back to the tail rotor.
  • helicopter 10 is a model helicopter, it will be understood that man-carrying helicopters (not shown) also have main rotors and tail rotor ⁇ , and that other type ⁇ of rotary wing aircraft (such as tilt rotor aircraft) u ⁇ e thru ⁇ t-producing appendage ⁇ that can operate in a ⁇ imilar fa ⁇ hion.
  • a detailed description of a suitable model helicopter configuration and structure is disclo ⁇ ed by Paul E. Arlton et. al. in U.S. Patent Application No. 08/292,718, filed Augu ⁇ t 18, 1994, which is hereby incorporated by reference herein.
  • a detailed description of a suitable tail rotor ⁇ y ⁇ tem is disclosed by Paul E.
  • main rotor 1 of helicopter 10 includes two rotor blades 17 and two shorter subrotor stabilizer blades 23 supported by a main rotor ⁇ haft (mo ⁇ tly hidden) aligned with main rotor axi ⁇ of rotation 5.
  • main rotor 1 rotates rapidly about main rotor axi ⁇ of rotation 5 in rotation direction 6.
  • main rotor blades 17 and ⁇ ubrotor blade ⁇ 23 act like propeller ⁇ or fan ⁇ moving large amount ⁇ of air downward thereby creating a force that lift ⁇ helicopter 10 upward.
  • the yaw torque (reaction force) created by rotating main rotor 1 in rotation direction 6 tends to cause helicopter 10 to swing about main rotor axis of rotation 5 in yaw direction 7 (angular motions of helicopter 10 about main rotor axis 5 are called “yaw motion ⁇ ", force ⁇ that tend to rotate helicopter 10 about main rotor axi ⁇ 5 are called “yaw moments" or “yaw torques”) .
  • tail rotor 2 propels air in direction 7 creating enough thrust force in direction 8 to exactly cancel the yaw torque produced by main rotor 1 so that helicopter 10 maintains a constant heading in flight.
  • tail rotor 2 Decreasing or increasing the thrust force of tail rotor 2, as by decreasing or increasing the collective pitch of tail rotor blades 11, will cau ⁇ e helicopter 10 to turn in yaw direction ⁇ 7 or 8 re ⁇ pectively.
  • the pilot of a full-size helicopter controls the collective pitch of tail rotor blades by manipulating foot pedals located within the cockpit. Cables, push-pull rods, mixing arms, and bellcranks connect the pedals to the pitch controls of the tail rotor blades.
  • the change in angle-of-attack (pitch) and as ⁇ ociated thru ⁇ t force of the rotating tail rotor blade ⁇ results in a yaw moment about the main rotor axis. This yaw moment is directed to maneuver the helicopter, or to oppose any destabilizing yaw moment sensed by the pilot.
  • Tail rotors of radio-controlled model helicopters operate in a manner identical to full-size helicopters.
  • the pilot manipulate ⁇ ⁇ mall joysticks on a hand-held radio trans itter which in turn sends commands to electro ⁇ mechanical servo actuator ⁇ located within the flying model.
  • Push-pull rods, mixing arms and bellcranks connect the servos to the collective pitch controls of the tail rotor blades.
  • tail rotor 2 illustratively includes two tail rotor blades 11, ⁇ pider 202, gyro ⁇ copic mechanism 12 having gyro paddles 59, gyro paddle grips 203, delta-drive bars 204, and gyro hub 62 ⁇ upported for rotation on gyro spindle 51 and rotating in rotation direction 13 about gyro rotor axis of rotation 500.
  • Tail rotor blades 11 preferably have reach-around grips 32, timing weight bolt ⁇ 34, and are of the aerodynamically balanced type de ⁇ cribed by Paul E. Arlton in U.S. Patent Application No. 08/292,719 which minimize or compen ⁇ ate for control link force ⁇ that might otherwi ⁇ e adver ⁇ ely affect gyroscopic mechanism 12.
  • gyroscopic mechanism 12 is operably mounted outboard of tail rotor 2 to rotate with tail rotor 2 and pivot about a sub ⁇ tantially horizontal gyro pivot axi ⁇ 553, ⁇ hown in Fig. 4, perpendicular to gyro rotor rotation axi ⁇ 500.
  • ⁇ ci ⁇ or-linkage 204, 205 tran ⁇ mits rotational motion of tail rotor 12 to gyroscopic mechanism 12 while gyroscopic mechanism 12 may tilt or translate relative to tail rotor 2.
  • rotation of helicopter 10 in yaw directions 7 or 8 cause ⁇ gyro ⁇ copic mechanism 12 to preces ⁇ (tilt) about gyro pivot axis 553 and displace control linkages 476, 475, 48, 199, thereby adju ⁇ ting the pitch of tail rotor blade ⁇ 11, and the corre ⁇ ponding thru ⁇ t force produced by tail rotor 2, to oppose the yaw motion.
  • Characteristic 1 The location of the gyro rotor.
  • Tail rotor ⁇ on mo ⁇ t modern helicopters come in two common configurations: one has a hollow shaft (like tail rotor shaft 184 in Fig. 2) with a pu ⁇ hrod (like push- pull rod 22) pas ⁇ ing through the center of the tail rotor shaft to control the pitch of the tail rotor blades, and the other configuration has a ⁇ olid shaft (like tail rotor shaft 219 in Fig. 16) with a control slider (like slider 230) and linkage ⁇ surrounding the tail rotor shaft to control the pitch of the tail rotor blades.
  • Control and stabilization systems in accordance with the present invention can be generalized for use with either tail rotor configuration.
  • the gyroscopic mechani ⁇ m of the present invention is located in one of three places: outboard of the tail rotor as shown in Figs. 4 through 7, between the tail rotor and gearbox as shown in Figs. 8 through 14, or beside
  • the gearbox (outboard of) the gearbox oppo ⁇ ite the tail rotor a ⁇ shown in Figs. 15 through 23. It may also be located on the back end of the gearbox at an angle (such as 90 degrees) to the tail rotor ⁇ haft, or on ⁇ ome other part of the aircraft remote from the tail rotor such as near the power train mechanics in the forward section of the helicopter such as at a forward location 449 of helicopter 10 shown in Fig. 1.
  • Each location require ⁇ unique mounting ⁇ tructure, and ha ⁇ advantage ⁇ in different application ⁇ .
  • the gyroscopic mechanism may be mounted directly to the gearbox, however, the mounting structure may be built more solidly than when mounted to the push-pull rod, and any operating forces generated by the gyro rotor (such as by a gyro rotor adapted to produce a thrust force) can be transmitted directly to the structure of the helicopter.
  • the gyro rotor When mounted at a distance from the tail rotor such a ⁇ at forward location 449 of helicopter 10 ⁇ hown in Fig. 1, the gyro rotor cannot take advantage of the exi ⁇ ting tail rotor mounting structure, but advantageously locates the weight of the gyroscopic mechanism forward in the aircraft thus pos ⁇ ibly avoiding an unde ⁇ irable tail-heavy condition.
  • Characteri ⁇ tic 2 The method bv which pilot and gyro rotor input ⁇ are combined. Some of the fundamental deficiencie ⁇ of many of the mechanical stabilization systems currently available can be traced to the way in which gyroscopic stabilization and pilot control functions are combined. A unique and novel quality of the present invention is the way in which pilot control inputs can be combined with stabilizing input ⁇ from the gyroscopic mechanism for mutually independent operation. To a large degree, mounting location dictate ⁇ the method by which pilot control and stabilizing inputs are combined, but in operation each method produce ⁇ similar results.
  • the two primary mechanical methods for combining pilot control inputs and stabilizing inputs are through mixing linkages, and by moving the gyroscopic mechanism linearly in space relative to the tail rotor.
  • Straight or angled bellcrank ⁇ or three-point mixing arm ⁇ , ⁇ uch as mixing arm 297 shown in Fig. 9, are used in the present invention to combine two mechanical inputs into one mechanical output for controlling tail rotor thrust.
  • These linkage ⁇ can be configured to magnify or reduce the inputs.
  • the linkages can also be configured to balance the inputs equally or emphasize one input over the other. For example, in Fig.
  • mixing arm 297 has multiple gyro-input pivots 310 receptive to adjustable link 298 for adju ⁇ ting the input of gyro rotor 290 relative to pilot input ⁇ tran ⁇ mitted through pilot pu ⁇ hrod 296 to pilot-input pivot 311 on mixing arm 297.
  • Mixing arm 297 is connected to push-pull rod 309 at output pivot 312 and di ⁇ place ⁇ push- pull rod 309 and ⁇ pider 307 to vary the pitch of tail rotor blades 11.
  • the pilot can forcibly override the gyro ⁇ copic mechani ⁇ m, but thi ⁇ place ⁇ an undesirable load on the pilot's controls, and require ⁇ an override mechani ⁇ m ⁇ uch as springs in the control sy ⁇ tem that do not permit direct control of the tail rotor blade ⁇ .
  • an override mechani ⁇ m ⁇ uch as springs in the control sy ⁇ tem that do not permit direct control of the tail rotor blade ⁇ .
  • ⁇ uch an override ⁇ y ⁇ tem would benefit from the other features of the present invention.
  • Hybrid electro-mechanical system ⁇ ⁇ uch a ⁇ that ⁇ hown in Fig. 10 offer a third method for combining pilot control and ⁇ tabilization input ⁇ .
  • the gyro linkage is electronic instead of mechanical, but perfor s the same function a ⁇ mechanical linkage ⁇ (to add a stabilizing input to the pilot's controls) , and controls the tail rotor through a tail rotor control servo instead of by directly di ⁇ placing the tail rotor pitch linkages.
  • electronic means such as a Hall-effect switch 322, as shown in Fig. 10, or other type of electric or electronic switch or potentiometer is used to sense rotor tilt.
  • the output signals from the switch are transmitted as by wires to an electronic servo control unit typically located in the body of the helicopter where they are electronically amplified and mixed with pilot control commands and directed to the tail rotor control servo.
  • Electronic amplification and mixing is common on electronic gyro sy ⁇ tems with electrically driven gyro rotors, but i ⁇ entirely novel and disclosed herein for the first time for u ⁇ e on system ⁇ with mechanically driven gyro rotor ⁇ .
  • the gyroscopic mechanism of a hybrid electro-mechanical system may be generally smaller than one designed for u ⁇ e on a purely mechanical system because it actuate ⁇ only a small switch or potentiometer rather than directly actuating the tail rotor blades.
  • a drawback of any electro-mechanical system is that the tail rotor control servo is in constant motion during flight. Such a condition can cause high wear on the servo, and can result in premature servo failure.
  • Characteristic 3 The method bv which the gyro rotor is driven.
  • the gyro rotor in various embodiments of the pre ⁇ ent invention may be driven through follower linkage ⁇ , through a univer ⁇ al joint, or by a direct connection to a drive ⁇ haft.
  • These gyro-rotor drive systems are discu ⁇ ed below.
  • follower links can generally be de ⁇ cribed a ⁇ any link or combination of linkage ⁇ that tran ⁇ mit rotational motion from one element in a rotating system to another element, and are characterized by their ability to transmit rotational motion around mechanical obstacles, across gaps, or between part ⁇ that mu ⁇ t move or tilt in relation to one another.
  • a good example of follower-linkages is found in Fig. 5 where scis ⁇ or links 201 comprising inner drive link 205 and delta-drive bar 204 transmit rotational motion from ⁇ pider 202 to gyro rotor 12 while gyro rotor 12 tilt ⁇ about pivot axi ⁇ 553 ( ⁇ hown in Fig. 4) and spider 202 slides along push-pull rod 22.
  • Follower links can also act as restoring means to return the elements of a rotating system to a nominal orientation or position by imparting a restoring force or control motion to the rotating elements.
  • Thi ⁇ contra ⁇ t ⁇ univer ⁇ al joints also called gimbals which are generally located on the axi ⁇ of rotation, and which typically do not impart ⁇ ignificant re ⁇ toring forces to the system.
  • Direct drive sy ⁇ tems such as that shown in Fig. 18, generally have a gyro rotor 253 with gyro rotor arms 254 pivotably connected to a drive shaft 258 to pivot or flap about flapping axes 259,260 which are substantially perpendicular to the shaft.
  • a remote gyro spindle 261 tilting about pivot pin 212 and connected to gyro rotor 253 by drive bars 256 typically constrain ⁇ the ⁇ pinning gyro rotor 253 to tilt about a ⁇ ingle effective pivot axi ⁇ located midway between flapping axes 259,260.
  • Characteristic 4 The method bv which the gyro rotor is restored.
  • the fourth way of characterizing the present invention is by the method in which the gyroscopic mechanism is re ⁇ tored to a nominal, unpivoted orientation when the helicopter stops rotating.
  • Mechanical spring forces, centrifugal (rotational) forces, and aerodynamic force ⁇ are used in various embodiment ⁇ to orient the gyro ⁇ copic mechanism.
  • Mechanical spring ⁇ such as 301 and 302 in Fig. 9 are relatively compact and produce re ⁇ toring force ⁇ that are dependent upon deflection, and independent of the operational ⁇ peed of the system. Springs are well suited for ⁇ y ⁇ tems operating at a constant rotational speed, because the restoring forces produced by the springs can be adjusted (tuned) to operate best within a small speed range. Con ⁇ tant speed rotor systems are common on full- size helicopters and model helicopters having collectively pitchable main rotor blades.
  • Centrifugal and aerodynamic mechanisms are usually more complicated than ⁇ pring mechani ⁇ m ⁇ , but produce restoring forces that vary with the operational speed of the system.
  • Centrifugal restoring means can be any device that takes advantage of the forces developed by rotational motion of any element of the control and ⁇ tabilization mechanism (such as weighted arms 352 operating in conjunction with spindle drive bars 353 a ⁇ ⁇ hown in Fig. 7) .
  • the gyroscopic forces that cause the gyroscopic mechanism to tilt when the helicopter yaws also vary with rotational ⁇ peed, ⁇ o centrifugal and aerodynamic re ⁇ toring mechanisms are well suited for use in sy ⁇ tem ⁇ that must operate over a wide speed range ⁇ uch a ⁇ ⁇ y ⁇ tems intended for u ⁇ e on model helicopter ⁇ with fixed-pitch main rotor blade ⁇ .
  • Characteri ⁇ tic 5 Gyro rotor adapted to produce a thru ⁇ t force.
  • the gyro ⁇ copic mechani ⁇ m of the current invention comprises a rotating disk with no aerodynamic properties, but in many alternative embodiments, the gyro rotor produce ⁇ aerodynamic drag. It is desirable for the gyro rotor to generate u ⁇ able thrust so that this drag is not produced without gain.
  • Simple gyro paddles (such as paddles 59 in Fig. 3) that do not pitch collectively with tail rotor blades 11, may be used to off-load or trim tail rotor 2, but can also reduce overall tail rotor 2 effectivenes ⁇ ⁇ ince tail rotor blade ⁇ 11 mu ⁇ t change pitch collectively to maneuver helicopter 10.
  • Collectively pitchable paddle ⁇ or blades are more complicated, but are preferred in some applications becau ⁇ e they can increa ⁇ e the thru ⁇ t potential of the tail rotor without adding appreciable drag.
  • the gyro rotor may be adapted for u ⁇ e a ⁇ a thrust-producing rotor. Since the gyro rotor must tilt in operation, it may seem to a casual observer that the thru ⁇ t produced by thi ⁇ tilted gyro rotor will be directed in variou ⁇ unwanted direction ⁇ . However, since means i ⁇ provided for cyclically pitching the gyro rotor blades, the airflow through the gyro rotor will not necessarily follow the same path as through a ⁇ imple tilted rotor.
  • the actual airflow direction will depend upon many factor ⁇ including the ⁇ ize and speed of the rotor system, the degree of tilt of the gyro rotor, the mass of the rotor blades, and the amount of cyclic pitch induced in the gyro rotor blade ⁇ .
  • the operational tilt of the gyro rotor in hybrid electro-mechanical systems is usually less ⁇ evere than in totally mechanical system ⁇ . Since electric and electronic switches can be very sen ⁇ itive, less rotor tilt is required, and consequently le ⁇ s de-stabilizing thrust i ⁇ produced, by a thrust-producing gyro rotor in an electro ⁇ mechanical system than by a similar gyro rotor in a totally mechanical system.
  • the gyroscopic mechanism of the current invention includes a spinning gyro rotor that is capable of pivoting about a gyro rotor pivot axis, and a gyro spindle that responds to pivotal displacement of the gyro rotor.
  • the gyro spindle 222 support ⁇ the gyro rotor 210 directly.
  • the gyro spindle 222 is located at a distance from the gyro rotor 253 and connected to the gyro rotor 253 with linkages 256.
  • gyro rotors illu ⁇ trated in the drawings are generally shown for clarity with two gyro arms extending radially from a central hub, it will be understood that gyro rotors having more than two arm ⁇ are advantageou ⁇ in certain embodiments ( ⁇ uch a ⁇ that shown in Fig. 18) . Additional arms increase the moment of inertia of the gyro rotor about axes perpendicular to the gyro rotation axis.
  • gyro rotor 253 cannot maintain the tilt angle of spindle assembly 261 when gyro rotor 253 ha ⁇ rotated about tail rotor axis of rotation 14 to a point where both gyro arms 254 are parallel to pivot pins 212. If gyro rotor 253 ha ⁇ three radially extending gyro arms 254 (and corresponding spindle drive bars 256) , it can provide the inertia needed to con ⁇ train ⁇ pindle assembly 261 at all times.
  • Figs. 4 through 27 illu ⁇ trate 22 preferred embodiments of the present invention for use on helicopter 10.
  • Figs. 4 through 23 illustrate ⁇ eventeen dual-rotor embodiments of the present invention for tail as ⁇ e blie ⁇ with variou ⁇ mechanical configuration ⁇ .
  • the figures are as ⁇ embled into three groups based on the location of the gyro ⁇ copic mechanism relative to the primary tail rotor and tail rotor gearbox. Within each group, the figures show variations of the basic operational elements that make up the invention.
  • Figs. 24 through 27 illustrate four embodiments of the present invention wherein the primary tail rotor and gyroscopic mechani ⁇ m have been combined into a ⁇ ingle rotor.
  • each embodiment compri ⁇ e ⁇ operational element ⁇ , such as mechanical linkages and drive means, that may be interchanged among the various embodiment ⁇ within the con ⁇ traint ⁇ impo ⁇ ed by the configuration of the helicopter for which that element is intended.
  • Fig. 2 is an exploded view of the tail boom assembly of helicopter 10
  • gearbox 15 is mounted at the end of tail boom 16 and encloses ball bearings 179, 180, bevel gears 182, 183, and tail rotor shaft 184 that together support and drive tail rotor 2 (shown in Fig. 1) .
  • Rotational motion from the power plant 3 of helicopter 10 is tran ⁇ mitted to tail rotor 2 (shown in fig. 1) attached to tail rotor hub 39 through a front bevel gear 69 (which is appended to a drive wire 70) , bevel gears 182, 183, tail rotor shaft 184, and a tail rotor hub 39.
  • tail boom 16 (shown in sectioned cut-away) has a center bushing 191 and end bushing ⁇ 190 at each end made of a pla ⁇ tic ⁇ material such a ⁇ Delrin which take the place of expen ⁇ ive ball bearings.
  • Gearbox bolt 193 pas ⁇ es through gearbox hole 194 formed in gearbox 15, and bolt slot 192 ( ⁇ hown in phantom in Fig. 2) near the end of tail tube 16, and into gearbox locknut 195 thereby securing gearbox 15 to tail tube 16.
  • Bushing recesses 196 are formed in end bushings 190 to allow for pas ⁇ age of gearbox bolt 193.
  • Tail tube bracket 197 i ⁇ provided to mount tail boom 16 to the fu ⁇ elage ⁇ tructure (not shown) of helicopter 10.
  • Pilot control commands actuate pilot pushrod 20 (having clevis 200) and bellcrank 21 as shown in Fig. 2.
  • Some embodiments of the present invention employ a push- pull rod 22 to tran ⁇ mit control commands through the center of tail rotor shaft 184 to tail rotor assembly 2 attached to tail rotor hub 39, in which case tail rotor shaft 184 i ⁇ nece ⁇ arily hollow a ⁇ shown.
  • Figs. 2a, 4, and 5 show an exploded view, top view, and rear end view, re ⁇ pectively, of the tail rotor a ⁇ embly 2 of helicopter 10 incorporating a first embodiment of the improved control and ⁇ tabilization ⁇ y ⁇ tem of the present invention.
  • gyro rotor 12 ha ⁇ gyro paddle ⁇ 59 extending radially from gyro hub 62, and is rotationally supported by gyro spindle 51.
  • Gyro spindle 51 is pivotably supported by gyro pivot pins 53 extending from gyro mount 52 which i ⁇ appended with ⁇ etscrew 50 (shown in Fig.
  • Gyro rotor 12 rotates about gyro rotor axis of rotation 500 (which normally coincides with tail rotor axis 14) and i ⁇ con ⁇ trained to pivot about a substantially longitudinal pivot axis 553 by pivot pins 53.
  • Semi-flexible gyro pu ⁇ hrod 475 transforms pivoting motion of gyro spindle 51 into translational motion, and is operably connected to gyro spindle 51 at gyro output pivot 476 which coincides with pivot link pin 56.
  • Spider slider 48 is operably connected to gyro spindle 51 through ⁇ emi-flexible gyro pushrod 475, and is free to move axially on push-pull rod 22.
  • Spider 202 is supported for rotation about tail rotor axis 14 by an annular reces ⁇ formed between eyelet 45 and ⁇ lider 48, and i ⁇ operably connected by spider arms 199 to the leading edge of each reach-around grip ⁇ 32 which are fixedly ⁇ ecured to each tail rotor blade 11 and blade balancing weight 34.
  • Tilt of gyro spindle 51 (a ⁇ would be cau ⁇ ed, for in ⁇ tance, by prece ⁇ ion of gyro rotor 12 about pivot pin ⁇ 53 due to yaw motion of helicopter 10) displaces gyro pushrod 475, spider ⁇ lider 48, and ⁇ pider 202 thereby varying the pitch of tail rotor blades 11 independent of pilot control inputs.
  • push-pull rod 22 is held in position by the pilot control system which typically includes pilot pushrod 20 (shown in Fig. 2) connected to bellcrank 21 (shown in Fig. 2) .
  • tail rotor hub 39 i ⁇ tran ⁇ ferred to gyro rotor 12 through blade grips 32 and ⁇ pider 202, ⁇ ci ⁇ sor-link 201 comprising inner drive links 205, and delta-drive bars 204 which are operably connected to gyro paddle grip ⁇ 203.
  • Gyro paddle grips 203 are fixedly secured to pivot rod portions 209 of gyro paddles 59, and pivotably connect gyro paddles 59 to gyro hub 62 for rotation about their respective pitch axe ⁇ 57,58.
  • delta-drive bars 204, and inner drive link ⁇ 205 tran ⁇ fer rotational motion to gyro rotor 12 regardle ⁇ of the tilt angle of gyro rotor 12 or the axial displacement of spider 202 on pu ⁇ h-pull rod 22.
  • Each delta-drive bar 204 has a drive pivot-leg portion 189 extending into drive link 205 and a delta pivot-leg portion 206 oriented to form an acute delta-angle with the pitching axi ⁇ of gyro paddle ⁇ 59. Pivot of gyro rotor 12 lead ⁇ to a cyclic change in pitch of gyro paddles 59 resulting in cyclic aerodynamic forces on gyro paddles 59 that tend to restore gyro rotor 12 to a nominal vertical orientation. In this way, ⁇ ci ⁇ or links 201 act as both drive means and restoring mean ⁇ for gyro rotor 12.
  • delta-drive bar 204 ⁇ hould be semi- flexible, or have an additional degree of freedom to rotate ⁇ lightly about its longitudinal axis, ⁇ ince operation of the delta mechani ⁇ m as illu ⁇ trated in Fig. 5 will induce small twisting force ⁇ in delta-drive bars 204.
  • spring means may interconnect delta-drive links, inner drive links, and/or spider to restore gyro rotor 12 to a nominal vertical orientation.
  • Delta-drive components are ⁇ o-named becau ⁇ e pivoting motion of gyro rotor 12 causes a pitching motion of gyro paddle ⁇ 59 in a manner conceptually ⁇ imilar to delta hinges on main rotor 1 of helicopter 10 (rotor hinge- axes are generally referred to with the Greek letter ⁇ Alpha, Beta, Gamma, and Delta) .
  • rotor hinge- axes are generally referred to with the Greek letter ⁇ Alpha, Beta, Gamma, and Delta
  • pivoting scis ⁇ or linkage ⁇ 201 offer less frictional resistance, and are more practical in many applications than are slidable drive bars (not shown) .
  • Delta-drive bar 204 is also known a ⁇ a delta Z-link and i ⁇ preferably made of metal wire bent into a Z- ⁇ hape. Formed wire Z-link ⁇ are especially inexpensive and simple in model helicopter application ⁇ .
  • Fig. 6 illu ⁇ trate ⁇ a second embodiment of the present invention with a gyro rotor 339 having gyro arms 340 terminating in gyro arm weights 348 instead of a gyro rotor having aerodynamic paddle ⁇ 59 as shown in Figs. 4 and 5.
  • slider 48 is displaced axially by pivoting motion of gyro spindle 51 which is pivotably supported by gyro mount 52 which is fixedly secured to the end of push-pull rod 22.
  • Crossbar 342 is pivotably mounted to spider 344 at crossbar pivot 345 so that axial di ⁇ placement of ⁇ lider 48 di ⁇ place ⁇ spider 344, crossbar 342, and drive bars 343 which are univer ⁇ ally connected to weighted gyro arm ⁇ 340 at ball joints 347.
  • Such axial displacement of cros ⁇ bar 342 and drive bars 343 cause ⁇ gyro arms 340 to "cone" about arm flapping pivots 346.
  • weighted gyro arms 340 are simpler to con ⁇ truct than gyro paddles 59 shown in Figs 4 and 5.
  • Fig. 7 Show ⁇ a third embodiment with gyro rotor 351 having weighted gyro arm ⁇ 352 extending radially from flapping pivot ⁇ 357 ⁇ ituated on the center portion of spider 355, and operably connected to ⁇ pindle hub 356 by ⁇ pindle drive bars 353 at ball joints 354. Rotational motion of tail rotor hub 39 is tran ⁇ ferred to gyro rotor 351 by follower-linkage ⁇ compri ⁇ ing reach-around grip ⁇ 32
  • Spindle hub 356 constrains gyro rotor 351 to tilt about a substantially longitudinal axis, and illustrate ⁇ the general concept of a remote gyro spindle con ⁇ training the tilt of a gyro rotor. Tilt of gyro rotor 351 causes spindle hub 356 to tilt, and displaces slider 48 axially.
  • ⁇ pindle hub 356 may be con ⁇ tructed more lightly than gyro hub 338 ⁇ hown in Fig. 6 because spindle hub 356 is not required to carry the radial centrifugal loads of weighted gyro arm ⁇ 352.
  • Figs. 8 and 9 show the top plan view and rear end elevational view, respectively, of the tail rotor a ⁇ sembly of helicopter 10 incorporating a fourth embodiment of the present invention having a gyro rotor 290 located between the tail rotor 2 and the gearbox 295.
  • gyro rotor 290 has weighted arms 291 extending radially from gyro hub 289, and is pivotably supported by gyro support arms 305 extending from gearbox 295.
  • Gyro rotor 290 normally rotates about gyro rotor axis 500 and is constrained to pivot about a substantially longitudinal pivot axis 512 by pivot pins 212 extending through gyro support arms 305 into gyro spindle 222.
  • Gyro hub 289 is supported by ball bearing inner race 217, and has an interior receptive to universal drive mean ⁇ on hollow tail rotor ⁇ haft 293.
  • tail rotor shaft 293 has universal drive means comprising a spherical bulge with drive pins extending radially therefrom and riding within axial slot ⁇ (shown in cut away in Fig. 8) in gyro hub 289 thereby transferring rotational motion of tail rotor shaft 293 to gyro rotor 290 while allowing gyro rotor 290 to pivot about pivot pins 212.
  • follower link drive means may be substituted for universal drive mean ⁇ .
  • gyro rotor 290 is shown supported for rotation by inner race 217, it may be supported by outer race 218 with appropriate modification to gyro support arms 305 and with modified mean ⁇ to combine pilot control and gyro stabilization inputs.
  • Gyro pushrod 303 is pivotably connected to gyro ⁇ pindle 222 at gyro output pivot 304, and transmits gyro ⁇ tabilization output ⁇ from gyro rotor 290 to three-point mixing arm 297 where they are combined with pilot control command ⁇ di ⁇ placing pilot pu ⁇ hrod 296.
  • Push-pull rod 309 transmits combined control and ⁇ tabilization commands through the center of hollow tail rotor shaft 293 to spider 307, and thereby to reach-around grip ⁇ 32 and tail rotor blades 11.
  • Gyro adjustment nuts 299 and 300 on gyro pu ⁇ hrod 303, and adju ⁇ table link 298 are operably connected to three-point mixer 297 at one of multiple gyro-input pivot point ⁇ 310.
  • Gyro-input pivot point ⁇ 310 are provided for adju ⁇ ting the gain and bandwidth of the stabilizing input to three-point mixer 297, and for adjusting the restoring force applied to gyro rotor 290.
  • Adjustable nuts 299 and 300 operate again ⁇ t springs 301 and 302 and may also be set to compen ⁇ ate for pitch-link force ⁇ ⁇ o that gyro rotor 290 maintain ⁇ a nominal vertical orientation even if tail rotor blade ⁇ 11 are not aerodynamically balanced or ma ⁇ balanced about their respective blade pitching axes 231.
  • gyro rotor 290 is shown with only two arms 291, gyro rotor 290 may have multiple arms. As previously discussed, multiple arms advantageously increase the moment of inertia of the gyro rotor about two axes thereby enabling the gyro rotor to more smoothly hold the tail rotor blades at a particular pitch if the tail rotor blades are not balanced to minimize pitch-link forces.
  • Fig. 10 shows a fifth, hybrid electro-mechanical embodiment of the present invention that is mechanically similar to the fourth embodiment shown in Figs. 8 and 9.
  • magnet means 321 is secured to gyro pushrod 323 in proximity to Hall-effect switch 322 ⁇ o that di ⁇ placement of magnet mean ⁇ 321 i ⁇ sensed by Hall-effect switch 322.
  • Tilt of gyro rotor 325 can be sensed electrically or electronically in many ways including rotary potentiometer mean ⁇ at gyro pivot 212, or linear potentiometer means or electronic counter means on gyro pushrod 323.
  • gyro arms 327 of gyro rotor 325 on hybrid electro-mechanical systems can be smaller than on totally mechanical systems because the motion of gyro rotor 325 is amplified electronically, so that gyro rotor 325 need not generate gyroscopic forces capable of moving tail rotor blade ⁇ ll directly.
  • a sixth embodiment shown in Fig. ll ha ⁇ a univer ⁇ al joint (hidden) inside gyro hub 313 to transmit rotary motion from tail rotor ⁇ haft 319 to gyro rotor 314, and pu ⁇ hrod collar ⁇ 316 for adju ⁇ ting the limit ⁇ of tilt of gyro rotor 314.
  • Pitch slider 317 is operably connected to spider 307 and blade grips 32 with spider links 318 so that pitch control inputs to tail rotor blades ll al ⁇ o control collectively-pitchable gyro rotor blade ⁇ 315.
  • Gyro rotor 314 i ⁇ restored by cyclic pitching of gyro rotor blades 315.
  • gyro rotor blade ⁇ 315 can produce a controllable thrust force to augment the thrust produced by tail rotor blade ⁇ 11.
  • Fig. 12 shows a seventh embodiment with offset gyro pivot 335, gyro pushrod 349, gyro output pivot 350, hollow tail rotor shaft 336, and follower link drive means comprising a scissor linkage for transferring rotational motion from tail rotor shaft 336 to gyro rotor 358 having drive bars 333 and inner drive links 334 operably connected to weighted arms 337 at ball joints 332.
  • spider 307 is connected to the trailing edge of tail rotor blade ⁇ 11.
  • An eighth embodiment shown in Fig. 13 has gyro rotor 426 pivotable about gyro pivot axis 427 extending radially from slider 428.
  • Gyro slider 428 is slidable on tail rotor shaft 429, rotatably supports spider 432 and gyro rotor 426, and is constrained again ⁇ t rotation by scissor links 430. Tilt of gyro rotor 426 about gyro pivot axis 427 cause ⁇ gyro rotor 426 to pu ⁇ h again ⁇ t pilot control pivot 431 (which doubles as the gyro output pivot) di ⁇ placing gyro rotor 426, ⁇ lider 428, and ⁇ pider 432 axially.
  • Semi-flexible link ⁇ 433 act both as follower link means to transmit rotational motion from tail rotor ⁇ haft 429 to gyro rotor 426 and as spring restoring means to return gyro rotor 426 to its nominal vertical orientation after gyro rotor 426 ha ⁇ been tilted.
  • Fig. 14 shows a ninth embodiment with thrust- producing gyro rotor 418 pivotable about gyro pivot axis 419 on slider 438.
  • Slider 438 is slidable on tail rotor shaft 439 and constrained against rotation by scissor links 407.
  • Gyro pushrod 440 is pivotably connected to gyro spindle 436 at gyro output pivot 437 and actuates slider 438 and spider 441 which is operably connected to three- point lever 442 at spider pivot 446.
  • Three-point lever 442 is operably connected at one end to ground link 443 attached to tail rotor shaft 439, and at the other end to drive bar 445, and reverses the direction of pitch control commands that collectively pitch gyro rotor blade ⁇ 444 so that gyro rotor blades 444 and tail rotor blades 11 pitch in the same direction.
  • Figs. 15 and 16 show a top plan view and rear end elevational view, respectively, of a tail rotor as ⁇ embly of helicopter 10 incorporating a tenth embodiment of the present invention having a gyro rotor 210 located outboard of a gearbox 214 opposite tail rotor 2 and pivotable about a gyro pivot axi ⁇ 555 defined by pivot pin ⁇ 212.
  • a gyro rotor 210 located outboard of a gearbox 214 opposite tail rotor 2 and pivotable about a gyro pivot axi ⁇ 555 defined by pivot pin ⁇ 212.
  • gyro rotor 210 has weighted arms 211 extending radially from gyro hub 213, and is pivotably supported by gyro support arms 215 extending from gearbox 214.
  • Gyro rotor 210 normally rotate ⁇ about tail rotor axi ⁇ of rotation 14 and i ⁇ constrained to pivot about a sub ⁇ tantially longitudinal pivot axi ⁇ 555 defined by pivot pin ⁇ 212 extending through gyro support arms 215 into gyro spindle 222.
  • Gyro hub 213 is supported by ball bearing inner race 217, and has an interior receptive to universal joint means on the end of solid tail rotor shaft 219.
  • tail rotor shaft 219 ha ⁇ universal drive means comprising a spherical end with drive pins 220 extending radially therefrom and riding within axial slots in gyro hub 213 thereby transferring rotational motion of tail rotor ⁇ haft 219 to gyro rotor 210 while allowing gyro rotor 210 to pivot about longitudinal pivot axis 555 defined by pivot pins 212 ("pin and ⁇ lot" type drive mean ⁇ are shown in more detail in Fig. 28) .
  • gyro rotor 210 is shown ⁇ upported for rotation on ball bearing inner race 217.
  • the gyro rotor may be ⁇ upported on a ball bearing outer race 218 with appropriate modification to the gyro support arms, and with modified means to combine pilot control and stabilization inputs.
  • Spider 229 is supported for rotation about tail rotor axis 14 by slider 230, and i ⁇ operably connected to the leading edge of reach-around grips 32 which are fixedly secured to tail rotor blades ll.
  • Slider 230 is pivotably connected to three-point mixing arm 225 at output pivot point 236, and i ⁇ free to move axially on tail rotor ⁇ haft 219.
  • pivot of gyro rotor 210 and gyro spindle 222 displaces gyro pushrod 223 and gyro-input pivot point 235 of three-point mixing arm 225 independent of pilot control input ⁇ .
  • Pilot control inputs displacing bellcrank 21 al ⁇ o di ⁇ place pilot pushrod 224 and pilot-input pivot point 237 of arm 225 independent of stabilizing inputs from gyro rotor 210.
  • Output pivot point 236, and consequently ⁇ lider 230 and spider 229, are displaced by the average of the displacement of gyro-input pivot point 235 and pilot-input pivot point 237 thereby combining pilot control and gyro stabilizing inputs to control the pitch of tail rotor blades 11 about blade pitching axi ⁇ 231.
  • Spring-restoring means 238, 239 act again ⁇ t pu ⁇ hrod guide ⁇ 207, 208 and gyro pushrod collar 240 affixed to gyro pushrod 223 to re ⁇ tore gyro rotor 210 to a nominal vertical orientation after helicopter 10 ha ⁇ ⁇ topped rotating.
  • FIG. 17 An eleventh embodiment ⁇ hown in Fig. 17 has no universal joint inside gyro hub 244 which instead is generally hollow to allow pivoting motion of gyro rotor 247 without interfering with tail rotor shaft 246.
  • Crossbar 245 is pivotably mounted to tail rotor shaft 246 at crossbar pivot 248 and drive ⁇ gyro rotor 247 through drive bar ⁇ 249 which are pivotably connected to crossbar 245 at drive bar pivots 244, and universally attached to gyro rotor 247 at ball joints 250.
  • Ball joints 250 are nece ⁇ ary for proper operation when gyro rotor 247 i ⁇ tilted about pivot pin 212 and rotated 90 degrees out of the plane of Fig. 17.
  • Spring-restoring mean ⁇ 251 operate ⁇ on crossbar 245 to restore gyro rotor 247 to a nominal vertical orientation.
  • the follower link ⁇ 245, 249 on thi ⁇ embodiment are more robu ⁇ t than universal joints, and allow the gyro rotor hub assembly 244 to be reduced in size.
  • Figs. 18 and 18a illu ⁇ trate a twelfth embodiment of the pre ⁇ ent invention having a remote ⁇ pindle a ⁇ embly 261 at a distance from a gyro rotor 253.
  • spindle hub 262 is generally hollow to allow uninhibited pivoting motion of ⁇ pindle as ⁇ embly 261 without interfering with tail rotor shaft 258.
  • Spindle as ⁇ embly 261 comprises spindle arms 263 extending radially from spindle hub 262 which is rotatably mounted to gyro spindle 222.
  • Gyro rotor 253 comprises gyro arms 254 extending radially from tail rotor shaft 258, and connected pivotably to arm extension ⁇ 264 and 265 which are fixedly ⁇ ecured to tail rotor shaft 258.
  • spindle assembly 261 is not ⁇ ubjected to the radial flight load ⁇ generated by gyro arm ⁇ 254, and can be more lightly built.
  • Spindle arm ⁇ 263 are operably connected to gyro arm ⁇ 254 by spindle drive bars 256 each having a ball joint 255 and gyro arm link pivot 257. Tilt of gyro rotor 253 is transferred by spindle drive bars 256 to gyro spindle 261 which constrains gyro rotor 253 to tilt about an effective gyro pivot axis 252 located midway between arm flapping pivot ⁇ 259 and 260 and parallel to pivot pin ⁇ 212 and gyro spindle pivot axis 555.
  • Spindle drive bars 256 al ⁇ o act a ⁇ follower-link drive member ⁇ by tran ⁇ ferring rotational motion from gyro rotor 253 to gyro ⁇ pindle 261 through a wide range of tilt angle ⁇ .
  • Arm flapping pivots 259, 260 define flapping axes for gyro arms 254 which are offset from and substantially perpendicular to gyro rotor axis 500, and which rotate along with gyro rotor 253.
  • gyro arms 254 are driven by tail rotor ⁇ haft 258 through arm flapping pivot ⁇ 259, 260, and act like a solid gyro rotor with an effective gyro pivot axis 252.
  • a ⁇ ⁇ hown in Fig. 18a, yaw motion of helicopter 10 in yaw direction 8 ( ⁇ hown in Fig. 1) cau ⁇ e ⁇ gyro rotor 253 to tilt through a gyro rotor pivot angle 242.
  • pivoting motion of gyro rotor 253 results in flapping motion of gyro arms 254 about arm flapping pivot ⁇ 259, 260.
  • centrifugal force ⁇ will act to orient gyro arms 254 perpendicular to tail rotor shaft 258 effectively restoring gyro rotor 253 to a nominal orientation.
  • Gyro hub 270 which is generally hollow to allow uninhibited pivoting motion of a gyro rotor 268 without interfering with tail rotor shaft 267.
  • Gyro rotor 268 comprises gyro rotor arms 269 extending radially from, and operably mounted to gyro hub 270.
  • gyro arms 269 are driven by tail rotor shaft 267 through follower-link elements including inner drive link pivots 274, drive links 273, arm-link pivots 276, and drive bar portion ⁇ 283 (which are fixedly secured to gyro arm 269) , and act like a solid gyro rotor which is constrained to pivot about a longitudinal axis 555, shown in Fig. 15, defined by pivot pin ⁇ 212.
  • pivoting motion of gyro rotor 268 results in flapping motion of gyro arms 269 about arm flapping pivots 272 becau ⁇ e drive link pivot ⁇ 274 do not coincide with pivot pin ⁇ 212.
  • FIG. 20 shows a fourteenth embodiment having universal drive means inside gyro hub 279 to transmit rotary motion from ⁇ haft 455 to gyro rotor 277.
  • Gyro rotor 277 comprises thrust producing gyro blades 278 extending radially from gyro hub 279, and operably mounted to gyro hub 279 to be rotatable about their respective pitching axes 459.
  • Displacement of ⁇ lider 230 and ⁇ pider 456, causes tail rotor blades ll to pitch collectively, and also displace spider 457 which is fixedly secured to transfer- pushrod 458 extending through hollow tail rotor shaft 455.
  • Pitch links 453 operably connect gyro blades 278 through crossbar 454 which is appended to transfer pu ⁇ hrod 458 ⁇ o that axial di ⁇ placement of tran ⁇ fer pu ⁇ hrod 458 causes gyro blades 278 to pitch collectively.
  • Tilt of gyro rotor 277 displacing gyro pu ⁇ hrod 223, and pilot control input ⁇ displacing pilot pushrod 224 can both displace ⁇ lider 230 along shaft 455 and thereby modify the collective pitch of tail rotor blades 11 and gyro rotor blades 278 simultaneously.
  • Tilt of gyro rotor 277 will also induce gyro blades 278 to pitch cyclically thereby generating aerodynamic forces to restore gyro rotor 277 to a nominal orientation.
  • the gyro blades may be replaced with other gyro rotor means such a ⁇ aerodynamic paddle ⁇ .
  • gyro hub 244 is generally hollow to allow pivoting motion of gyro rotor 247 about offset gyro pivot 328 without interfering with tail rotor shaft 246.
  • Semi-flexible crossbar 329 drives gyro rotor 247 through drive bars 331 which are pivotably connected to ⁇ emi-flexible cro ⁇ bar 329 and univer ⁇ ally attached to gyro rotor 247 at ball joints 250. Spring force caused by deflection of ⁇ emi-flexible cro ⁇ sbar 329 tends to orient gyro rotor 247 to a vertical nominal orientation.
  • crossbar 329 and drive bars 331 act as both drive mean ⁇ and restoring means for gyro rotor 247.
  • Ball joint ⁇ 250 are necessary for proper operation when gyro rotor 247 is tilted about off ⁇ et gyro pivot 328 and rotated 90 degree ⁇ out of the plane of Fig. 21.
  • spider 229 is connected to the trailing edge of tail rotor blade 11 ⁇ o that tail rotor blade 11 produce ⁇ ⁇ tabilizing thru ⁇ t force ⁇ in oppo ⁇ ition to yaw motion of helicopter 10.
  • Fig. 22 illustrates a sixteenth embodiment having a gyro rotor 277 mounted to pivot about offset gyro pivot
  • Gyro rotor 277 comprises thrust producing gyro blade ⁇ 278 extending radially from gyro hub 279, and operably mounted to gyro hub 279 to be rotatable about their respective pitching axes 288.
  • Pitch links 280 operably connect tail rotor shaft 281 to gyro blade ⁇ 278 through cro ⁇ bar 282 affixed to shaft 281 so that tilt of gyro rotor 277 induces gyro blades 278 to pitch cyclically, thereby generating aerodynamic forces to restore gyro rotor 277 to a nominal orientation.
  • gyro pu ⁇ hrod 223 passes ⁇ through motion damper 221 which minimizes unwanted high frequency motion of gyro rotor 278.
  • gyro rotor 277 will not automatically orient vertically because the thrust it produces is coincident with tail rotor axis of rotation 14 while it pivots about offset gyro pivot 328.
  • a ⁇ mall tilt i ⁇ required to cyclically pitch gyro rotor blades 278 to balance the thru ⁇ t force with a re ⁇ toring force.
  • FIG. 23 A ⁇ eventeenth embodiment ⁇ hown in Fig. 23 ⁇ hows the present invention having a gyro rotor 405 operably mounted to a gyro slider 411 and pivotable about a gyro pivot 406.
  • Gyro slider 411 i ⁇ ⁇ lidable on tail rotor shaft 412 and constrained against rotation by ⁇ cissor links 407.
  • Tilt of gyro hub 415 by gyro rotor 405 displaces gyro pushrod 404 which actuates pitch slider 413 and spider 229 to vary the pitch of tail rotor blades 11.
  • Drive bars 408 drive gyro rotor 405 which has aerodynamic restoring means in the form of gyro paddles 414 that pitch cyclically in response to tilt of gyro rotor 405.
  • FIG. 24 through 27 illustrate embodiments of the present ' invention in which the gyro- ⁇ tabilizing part and thru ⁇ t-producing part have been combined into a ⁇ ingle thrust-producing gyro rotor.
  • Fig. 24 shows a first combined single-rotor embodiment of the present invention with gearbox 214 configured as shown in Fig. 15, and having universal drive means inside gyro hub 279 to transmit rotary motion from hollow shaft 514 to gyro rotor 277.
  • Gyro rotor 277 comprises thrust-producing gyro blades 278 extending radially from gyro hub 279, and operably mounted to gyro hub 279 to be rotatable about their re ⁇ pective pitching axe ⁇ 275.
  • Pitch link ⁇ 516 operably connect push-pull rod 515 to gyro blades 278 through crossbar 517.
  • Cros ⁇ bar 517 is operably appended to the end of push-pull rod 515 to tran ⁇ late with push-pull rod 515, and to rotate with gyro rotor 277. Tilt of gyro rotor 277 about a coplanar pivot axis 555 ⁇ hown in Fig. 15 and defined by pivot pin ⁇ 212, a ⁇ may be induced by yaw motion of a helicopter, displaces gyro pushrod 223, three-point mixing arm 225 and push-pull rod 515 (through the center of hollow shaft 514) cau ⁇ ing gyro rotor blades 278 to pitch collectively to produce a thrust force which opposes the yaw motion.
  • Fig. 25 Shows a second single-rotor embodiment of the current invention having universal drive mean ⁇ in ⁇ ide a gyro hub 313 to tran ⁇ mit rotary motion from a hollow ⁇ haft 525 to a gyro rotor 314.
  • Gyro rotor 314 comprises thrust producing gyro blades 315 extending radially from gyro hub 313, and operably mounted to gyro hub 313 to be rotatable about their respective pitching axes 275.
  • Pitch links 526 operably connect push-pull rod 528 to gyro rotor blades 315 through cross bar 527.
  • Cross bar 527 is operably appended to the end of push-pull rod 528 to tran ⁇ late with pu ⁇ h-pull rod 528, and rotate with gyro rotor 314.
  • Tilt of gyro rotor 314 di ⁇ places gyro pushrod 529 and magnet means 321, and is limited by adjustable pushrod collars 316 appended to pushrod 529.
  • Tilt of gyro rotor 314 also induces gyro blades 315 to pitch cyclically thereby generating aerodynamic forces to restore gyro rotor 314 to a nominal orientation. Note that this single-rotor embodiment is related to the dual-rotor embodiments shown in Figs. 10 and 11, with tail rotor blades 11 and other interconnected linkages removed.
  • pilot control command ⁇ operate a tail rotor control ⁇ ervo-actuator located within the body of helicopter 10 ( ⁇ hown in Fig. 1) which displaces pushrod 20 ( ⁇ hown in Fig. 1) , bellcrank 21 (shown in Fig. 25) , push- pull rod 528, cro ⁇ bar 527, and pitch link ⁇ 526 thereby controlling the collective pitch of gyro blades 315.
  • magnet means 321 is illustratively secured to gyro pushrod 529 in proximity to Hall-effect switch 322 appended to gearbox 295 so that any displacement of magnet mean ⁇ 321 i ⁇ ⁇ ensed by Hall-effect switch 322.
  • tilt of the gyro rotor can be sensed electrically or electronically in many way ⁇ including rotary potentiometer mean ⁇ at the gyro pivot, or linear potentiometer mean ⁇ or electronic counter mean ⁇ on the gyro pu ⁇ hrod.
  • Fig. 26 Show ⁇ a third single-rotor embodiment of the present invention with gearbox 214 configured as shown in Fig.
  • gyro hub 378 operably mounted to a tail rotor shaft 383 and driven by gyro pivot pins 379 which rotate with shaft 383.
  • Spindle as ⁇ embly 381 is operably mounted to gyro support arms 215 on gearbox 214 to pivot about a pivot axis 555 defined by pivot pins 212.
  • Gyro rotor 377 compri ⁇ e ⁇ thrust producing gyro blades 278 extending radially from gyro hub 378, and operably mounted to gyro hub 378 to be rotatable about their respective pitching axes 275.
  • Pitch links 386 operably connect push-pull rod 385 to gyro blades 278 through crossbar 382.
  • Cros ⁇ bar 382 i ⁇ operably appended to the end of push-pull rod 385 to translate with pu ⁇ h-pull rod 385, and to rotate with gyro rotor 377.
  • Tilt of gyro rotor 377 as may be induced by yaw motion of helicopter 10, displace ⁇ gyro pu ⁇ hrod 223, three-point mixing arm 225, and pu ⁇ h-pull rod 385 (through the center of hollow ⁇ haft 383) .
  • Di ⁇ placement of push-pull rod 385 moves pitch links 386, causing gyro rotor blades 278 to pitch collectively to produce a thru ⁇ t force which oppo ⁇ es the yaw motion of helicopter 10.
  • Tilt of gyro rotor 377 also induce ⁇ gyro blades 278 to pitch cyclically thereby generating aerodynamic forces to restore gyro rotor 377 to a nominal orientation.
  • this ⁇ ingle-rotor embodiment supports gyro rotor 377 on shaft 383 instead of on ⁇ pindle assembly 381, so that spindle a ⁇ embly 381 may be lighter and more compact.
  • Fig. 27 illu ⁇ trate ⁇ a fourth single-rotor embodiment of the present invention having pitch control linkage ⁇ that al ⁇ o act a ⁇ follower linkage ⁇ .
  • a gyro hub 62 i ⁇ rotatably mounted to a gyro spindle 366 which is pivotably mounted to push-pull rod 22 and constrained to tilt about offset coplanar pivot axis 365 defined by gyro pivot pin 367 which is spatially offset from tail rotor axis 14 by a distance 371.
  • Shaft arms 362 are rigidly mounted to tail rotor shaft 368, and drive gyro rotor 363 through drive bars 369 which are univer ⁇ ally connected to the leading edge ⁇ of gyro rotor blades 364 at ball joints 370.
  • Pilot control commands displacing push- pull rod 22 displace gyro rotor 363 axially along tail rotor axi ⁇ of rotation 14 cau ⁇ ing gyro rotor blade ⁇ 364 to pitch collectively thereby altering the thru ⁇ t of gyro rotor 363.
  • Tilt of gyro rotor 363 about off et pivot axis 365 as may be induced by yaw motion of helicopter 10, di ⁇ place ⁇ the center of gyro rotor 363 axially which cau ⁇ e ⁇ gyro rotor blade ⁇ 364 to pitch collectively to oppo ⁇ e the yaw motion of helicopter 10.
  • Tilt of gyro rotor 363 also cau ⁇ es gyro rotor blades 364 to pitch cyclically and generate aerodynamic forces to re ⁇ tore gyro rotor 363 to a nominal orientation.
  • ⁇ eparate follower linkage ⁇ may be added between ⁇ haft 368 and gyro hub 62 to drive gyro rotor 363 and reduce the operational forces felt by drive bars 369 and ⁇ haft arms 362.
  • gyro rotor 363 will not automatically orient vertically becau ⁇ e the thru ⁇ t it produce ⁇ i ⁇ coincident with tail rotor axi ⁇ of rotation 14 while it pivot ⁇ about offset pivot axis 365.
  • a small tilt i ⁇ required to cyclically pitch gyro rotor blades 364 to balance the thrust force with a re ⁇ toring force.
  • spring means may be added between push-pull rod 22 and gyro spindle 366 to balance the thrust force. It should be noted that the device shown in Fig.
  • Two compact universal drive mechanism ⁇ each having only two functional part ⁇ , are provided herein to drive gyro rotors, and are particularly well suited for application to model helicopters.
  • the first type shown in Fig. 28, i ⁇ referred to herein a ⁇ the "pin-and-slot" type, and may be advantageously employed on gyro sy ⁇ tem ⁇ having a solid tail rotor shaft.
  • the second type shown in Fig. 29, i ⁇ referred to herein a ⁇ the "hexagonal" type, and may be used with a solid shaft, but i ⁇ most useful with hollow shafts having a pushrod extending through the center of the shaft. Referring now to Fig.
  • a pin-and- ⁇ lot universal drive has drive ball portion 490 with drive pin ⁇ 491, 492 extending radially therefrom and engageable within axial slots 493 and 494 formed in drive yolk 495.
  • drive yolk 495 is appended to a gyro rotor hub such as gyro hub 213 shown in Figs. 15 and 16.
  • Drive pins 491, 492 are preferably the expo ⁇ ed end ⁇ of a single pin made from a material such as hardened steel, and press-fit through a transverse aperture formed in drive ball portion 490 of tail rotor shaft 496 that is perpendicular to tail rotor axis of rotation 14.
  • Drive yolk 495 is preferably hardened steel, and can be insert molded or pres ⁇ ed into a pla ⁇ tic gyro hub for u ⁇ e on model helicopter ⁇ . In operation, drive ball 490 center ⁇ drive ⁇ haft 496 within drive yolk 495 through a range of engagement angle ⁇ (typically ⁇ 20 degree ⁇ as illustrated by arrow 498) between drive ⁇ haft 496 and yolk 495.
  • a hexagonal-type universal drive shown in Fig. 29 has hexagonal drive portion 503 with a multitude of curved drive faces 504 engageable within the multifaceted interior of universal hex housing 505.
  • Each drive face 504 of drive portion 503 has a corresponding interior face 506 inside universal housing 505 such that drive portion 503 can transmit rotational motion of shaft 508 to universal housing 505 through a wide range of engagement angles (typically ⁇ 20 degrees as illustrated by arrow 507) .
  • hexagonal-type univer ⁇ al drive ⁇ may be made hollow to accommodate a pu ⁇ hrod extending through a hollow ⁇ haft (such as transfer pushrod 458 inside hollow ⁇ haft 455 in Fig. 20) to control the pitch of the tail rotor or gyro rotor blades.
  • hexagonal drive portion 503 and univer ⁇ al drive hou ⁇ ing 505 may be made of a light weight material ⁇ uch a ⁇ aluminum, and hard-coat anodized to provide a wear-re ⁇ istant surface.
  • Drive hou ⁇ ing 505 may have ⁇ urface geometry, ⁇ uch a ⁇ annular ⁇ lot 509, to be insert molded or pres ⁇ ed into a plastic gyro hub such as gyro hub 279 in Fig. 20. It will be understood that hexagonal-type universal drives may have more or fewer than ⁇ ix driving face ⁇ .
  • gyroscopic mechanisms and linkage ⁇ of the pre ⁇ ent invention have been ⁇ hown in ⁇ tandardized positions for the purpose of illustrating preferred embodiment ⁇ , it will be under ⁇ tood that they may be located above, below, in front of or behind the gearbox or tail boom depending upon the specific requirements of the application. Said mechanism and linkages may also be oriented at an angle relative to the tail rotor shaft as when the gyro rotor is mounted to rotate about an axis parallel to the tail boom and perpendicular to the tail rotor shaft. It will be further understood that the gyro rotor pivot axis of each embodiment need not be horizontal, but may be set to any angle such as to couple roll and yaw motions.
  • the various components of the invention may be located elsewhere on the helicopter.
  • the gyroscopic mechani ⁇ m i ⁇ located in the forward section of the aircraft such a ⁇ at forward gyro location 449 of helicopter 1 ⁇ hown in Fig. 1 ⁇ hown in Fig. 1
  • the gyroscopic mechanism in such location 449 is preferably a solid wheel or hoop (not shown) with mechanical restoring means (not shown) such as ⁇ pring means or centrifugal means.
  • Various means are provided herein to support, restore, and drive the mechani ⁇ m from the engine, main rotor ⁇ haft, tail rotor drive wire, etc.
  • gyroscopic stabilization and pilot control inputs are best combined near forward gyro location 449, and transmitted mechanically (as by pushrod linkages and mixing arms) or electronically (as through the tail rotor servo) to the thrust-producing mean ⁇ located at the end of the tail boom.
  • a simple electronic element for sensing gyro rotor tilt would have a rotary potentiometer operably connected to the pivot axis of the gyro rotor and electronically mixed with pilot control inputs to the tail rotor control servo.
  • FIG. 1 For aircraft such as helicopters with blown tail booms (such as the NOTAR sy ⁇ tem by McDonnell Douglas Helicopter Company) where the thrust-producing mean ⁇ i ⁇ located at the front of the tail boom in ⁇ tead of at the rear.
  • NOTAR ⁇ y ⁇ tem ⁇ lack the natural yaw-damping capabilitiesitie ⁇ of traditional tail rotor ⁇ , and can benefit greatly from the stabilizing features of the present invention.
  • the gyroscopic mechani ⁇ m may be located in front of, behind, to the ⁇ ide ⁇ of, or remotely from the thru ⁇ t producing mean ⁇ . Control and stabilization commands may be used to modify or direct the thru ⁇ t a ⁇ it exit ⁇ the tail boom in addition to controlling the magnitude of the thru ⁇ t force.
  • gyro rotor is driven at a different speed than the thrust producing means as through the u ⁇ e of drive gear ⁇ with different speed ratios.
  • Gyroscopic mechanisms generally become more ⁇ en ⁇ itive and powerful when operated at higher rotational ⁇ peed ⁇ . Therefore, if operated at a different, generally higher speed than the thrust-producing means, the gyro rotor may be smaller, lower in weight, and less obtrusive. Thi ⁇ would be e ⁇ pecially advantageou ⁇ at forward gyro location 449 shown in Fig. l.
  • the gyro rotor pivot axis may lie near or within the gyro rotor plane of rotation.
  • a "coplanar pivot axi ⁇ " is generally any axis which lies in, or pas ⁇ es close to, the plane of rotation of the gyroscopic mechani ⁇ m.
  • the plane of rotation of the gyro ⁇ copic mechani ⁇ m i ⁇ usually taken as a plane (such as a plane 275 ⁇ hown edge-on in Fig.
  • the gyro pivot axis can be oriented more parallel to the aircraft rotation axis, and the operation of the stabilizer will then be governed more by angular displacement of the aircraft than by the speed of rotation of the aircraft.
  • Gyro control means generally refers to control linkages (which can include, for instance, mechanical, hydraulic or electric/electronic devices) that are operated in re ⁇ pon ⁇ e to pivoting motion of a gyro rotor.
  • Gyro control means frequently includes a member, ⁇ uch a ⁇ gyro pu ⁇ hrod 303 ⁇ hown in Fig. 9, which i ⁇ di ⁇ placed axially along tail rotor axis of rotation 14, and can transmit gyro control inputs away from the gyro rotor to ⁇ ome other point on the aircraft.
  • Gyro control linkage ⁇ and electrical mean ⁇ may be located entirely in proximity to the gyro ⁇ copic mechani ⁇ m, or extend to a remote location on the aircraft where they are combined with pilot control command ⁇ .
  • pilot control means generally refers to control linkages (which can include for in ⁇ tance, mechanical, hydraulic or electric/electronic device ⁇ ) that are responsive to pilot control commands. Such control commands may originate, for instance, from a pilot located within the cockpit of a full-size helicopter, or from a pilot located on the ground with a radio transmitter.
  • thrust control means generally refers to control linkages (which can include for instance, mechanical, hydraulic or electric/electronic devices) that can vary the magnitude and/or direction of a force that can be used to direct or orient an aircraft in flight.
  • Such thrust control mean ⁇ may, for in ⁇ tance, alter the pitch of tail rotor blade ⁇ 11 on helicopter 10 to vary the thrust produced by tail rotor 2 (shown in Fig. l) .
  • To "vary the thrust” of ⁇ uch thrust control means may also involve changing the direction of the thru ⁇ t force (a ⁇ when redirecting a controllable exhau ⁇ t port on the end of a blown tail tube anti-torque ⁇ ystem such as NOTAR system) .

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Abstract

Selon la présente invention, un hélicoptère (10) est pourvu d'un dispositif stabilisant le mouvement de lacet grâce à un rotor anticouple (2) à plusieurs pales rotor (11) disposées en rayon au départ d'un arbre rotor (15) creux monté en rotation autour d'un axe rotor (14) transversal. Le rotor anticouple (2) est équipé d'un dispositif (22) permettant au pilote d'intervenir sur les pales (11) du rotor anticouple (2) de façon à en modifier la poussée, un rotor de gyroscope (12) assurant la commande automatique du rotor anticouple (2). L'invention concerne également un embiellage mélangeur (297) trois points permettant de commander le rotor anticouple (2) non seulement grâce aux interventions (296) du pilote mais également grâce aux commandes en asservissement (310) du rotor de gyroscope.
EP96928019A 1995-07-27 1996-07-26 Systeme de regulation et de stabilisation automatique du mouvement de giration d'un aeronef a voilure tournante Ceased EP0869901A4 (fr)

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US155895P 1995-07-27 1995-07-27
US1558 1995-07-27
US707995P 1995-10-24 1995-10-24
US7079 1995-10-24
PCT/US1996/012322 WO1997005017A1 (fr) 1995-07-27 1996-07-26 Systeme de regulation et de stabilisation automatique du mouvement de giration d'un aeronef a voilure tournante

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US11040785B2 (en) * 2018-04-16 2021-06-22 Bell Helicopter Textron Inc. Devices and methods to verify tail rotor cross-head positioning
CN111470033B (zh) * 2020-05-14 2023-05-16 芜湖丽勤光电技术有限公司 一种小型飞机尾部平衡装置
CN112594131B (zh) * 2020-11-26 2022-04-26 中国船舶重工集团海装风电股份有限公司 一种风力发电机组侧风偏航控制方法、系统及相关组件
EP4086171B1 (fr) * 2021-05-05 2023-11-22 AIRBUS HELICOPTERS DEUTSCHLAND GmbH Appareil de réglage d'angle de pas cyclique
CN113815854A (zh) * 2021-10-29 2021-12-21 湖南韬讯航空科技有限公司 一种飞行器旋翼系统及控制方法

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Also Published As

Publication number Publication date
WO1997005017A1 (fr) 1997-02-13
JPH11510127A (ja) 1999-09-07
EP0869901A4 (fr) 2000-10-04
AU6763296A (en) 1997-02-26

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