Abstract:
A torque resisting device for a helicopter which comprises a body, a first rotor and a tail rotor wherein the device comprises a deflector secured to and moveable relative to the body, wherein the deflector is positioned between the main rotor and the tail rotor and wherein the deflector is positioned generally aligned with the body in a non-deployed position and a portion of the deflector is positioned spaced apart from the body in a deployed position. Additionally, a method to counteract torque in the operating of a helicopter.

Description:
FIELD OF THE INVENTION 
     The present invention relates to helicopters and more particularly to helicopters utilizing a main rotor, and a tail rotor for countering the torque created by the main rotor thereby controlling the lateral movement of the helicopter. 
     BACKGROUND 
     Most helicopters have a single, main rotor but these helicopters also require a separate rotor to overcome torque generated by the main rotor. The single, main rotor blades are generally oriented to rotate in a horizontal plane and the separate rotor blades, oftened positioned in the tail of the craft, are generally oriented to rotate in a vertical plane. 
     The single main rotor of a helicopter, as the engine rotates it, creates a counter-torque. The torque causes the body of the helicopter to turn or rotate in the opposite direction that the rotor rotates. The tail rotor, provided with variable pitched blades, through its rotation, either pushes or pulls against the tail to counter the torque imparted by the main rotor to the body of the helicopter. 
     If the tail rotor fails in flight, engine torque can no longer be countered by the tail rotor, and uncontrolled spinning of the aircraft, driven by the torque generated by the main rotor rotation, is a common result. The pilot has to identify and diagnose the type of tail rotor failure and react accordingly with the correct control strategy within a few seconds to prevent the helicopter from reaching an uncontrollable flight state. There is a need for a device that can automatically provide sufficient torque counter-action upon the loss or failure of a tail rotor to increase the amount of time a pilot has to react to the tail rotor failure thereby increasing the pilot&#39;s chances of ultimately safely landing the helicopter. There is also need for a device that can provide sufficient torque counter-action upon the loss or failure of a tail rotor to provide enough directional stability at normal cruising speeds so that a pilot can continue on course or maintain altitude until a suitable landing area is reached. 
     SUMMARY 
     A torque resisting device for a helicopter wherein the helicopter has a body, a main rotor and a tail rotor comprising a deflector secured to and movable relative to the body, wherein the deflector is positioned between the main rotor and the tail rotor and wherein the deflector is positioned generally aligned with the body in a non-deployed position and a portion of the deflector is positioned spaced apart from the body in a deployed position. 
     A method for counteracting torque in the operation of a helicopter having a main rotor and a tail rotor following the failure of the tail rotor comprising the steps of providing a deflector secured to the helicopter in a position between the main rotor and the tail rotor, wherein the deflector is positioned generally aligned with a body of the helicopter and deployable to another position wherein a portion of the deflector is positioned spaced apart from the body, deploying the deflector to the other position with occurrence of rotational movement of the body of the helicopter resulting from torque imparted to the body from the rotation of the main rotor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of an example of a helicopter; 
         FIG. 2  is a partially cut away top view of the helicopter of  FIG. 1 ; 
         FIG. 3  is a partial cutaway perspective view of the helicopter of  FIG. 1  along with an embodiment of a drag resistant deployment device; and 
         FIG. 4  is a partially cut away top view of the helicopter of  FIG. 1  providing a schematic view of pedals and their linkage to the actuator. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an example of a helicopter, generally designated  10 . In this example, helicopter  10  includes a fuselage  15  having a front portion  20  with a cockpit  25 , an intermediate portion  30  and a tail portion  35 . A rotary shaft  40  extends upward from the intermediate portion  30  and main rotor  45  is generally horizontally mounted on the rotary shaft  40 . The end of the tail portion  35  includes a tail fin  50  which extends generally in a vertical direction from tail portion  35 . In this example, the tail rotor  55  is mounted on the tail fin  50  and rotates in a plane generally perpendicular to main rotor  45 . It is understood, however, that tail rotor  55  may also be mounted directly in the tail portion  35 . Both the main rotor  45  and the tail rotor  55  are driven by an engine of the helicopter  10  through a common transmission and rotate at a certain ratio to each other. For example, the tail rotor  55  may rotate five times for every one time the main rotor  45  rotates. As the engine of the helicopter  10  rotates the main rotor  45  in one direction, torque is created causing the fuselage  15  to rotate in the opposite direction. The rotation of the tail rotor  55  creates a thrust that counteracts the torque that the main rotor  45  produces thereby allowing the helicopter  10  to maintain its heading and provide yaw control. 
     Yaw is controlled by changing the pitch of the tail rotor  55 , thereby controlling thrust. The pitch of tail rotor  55  is controlled by right and left rudder pedals schematic representation of these pedals can be seen in  FIG. 4 . To turn the nose of the helicopter right, for example, depressing the right rudder pedal decreases the pitch of the tail rotor  55  thereby reducing thrust and the torque then turns the helicopter nose right. Depressing the left rudder pedal increases the pitch of the tail rotor  55  thereby increasing thrust and turning the nose of the helicopter left. A balanced performance between main rotor  45  and tail rotor  55  at normal flight would generally be a neutral position of the right and left rudder pedals. The RPM&#39;s of the main rotor  45  and the tail rotor  55  are fairly constant. For instance, if the main rotor  45  is operating at 300 RPM, then the tail rotor is operating at approximately 1500 RPM. There may be a slight variation in the ratio at which the two rotors operate, up to five percent. Undesirable performance of tail rotor  55  would be any drop in RPM&#39;s in relationship to the RPM&#39;s of the main rotor  45  outside of that five percent variation. 
     A tachometer  60  is a typical device that senses the number of rotations of, for example, a rotor over a period of time, also mounted on the tail fin  50  and is operatively associated with the tail rotor  55  to sense the (revolutions per minute) RPM&#39;s of the tail rotor  55 . Tachometers are well known and commonly used in the aircraft industry, and one of ordinary skill in the art would be able to select an appropriate tachometer for use in the present example. While the helicopter  10  in this example utilizes a tachometer  60  to sense the RPM&#39;s of the tail rotor  55 , any sensing devices known in the art capable of sensing the RPM&#39;s of the tail rotor  55  may be used and such data readily compared to the RPM&#39;s of the main rotor (also, being monitored by a tachometer, for example) and thereby monitor the two rotors as to whether they are operating within acceptable comparable RPM&#39;s for normal operation. 
     A deployable deflector  65 , in this example, is pivotally connected to a side of the tail portion  35  of the fuselage  15 . Deflector  65  may be a portion of fuselage  15  or may be a structure separate from fuselage  15 . The deflector  65  may be made from standard aircraft materials such as aluminum or composite material such as carbon fiber or the like and is properly reinforced. A deflector lock  67  on the tail portion  35  of the fuselage  15  adjacent the deflector  65  engages the deflector  65  and locks it in a closed position in which the deflector  65  is positioned closely adjacent to or is positioned flush with the side of the tail portion  35  of the fuselage  15 . 
     The deflector  65  is operatively associated with an actuator  70  for deploying of deflector  65  such that at least of portion of the deflector  65  is positioned spaced apart from the body of the helicopter to engage the airflow and provide torque resistance. In the example shown, deflector  65  is hinged to the body of the helicopter such that deflector  65  rotates outwardly in a direction away from the body of the helicopter into a deployed position to provide torque resistance. The actuator  70 , for example, can be hydraulic or electric and of the type commonly used in the aircraft industry. The actuator  70  and the deflector lock  67  are operatively associated with the tachometer  60  such that when the tachometer  60  senses a loss of RPM&#39;s in the tail rotor  55  below its acceptable RPM&#39;s for normal operation, the deflector lock  67  is released and the actuator  70  is automatically activated thereby deploying the deflector  65  to a position transverse to a longitudinal axis of the tail portion  35  of the fuselage  15 , shown in  FIGS. 2 and 3 . The actuator  70  may also deploy the deflector  65  when a signal from the tachometer  60  is lost altogether, for example if the tail rotor  55  is shot off of the helicopter  10 . 
     As the helicopter  10  travels forward at a normal cruising speed, sufficient drag is created by the deflector  65  to counteract the torque created by the rotation of the main rotor  45 , enough to allow an operator to maintain its heading and provide yaw control. For instance, if the helicopter  10  is traveling at  120  MPH, a deflector  65  having a surface area of one square foot deployed to a 90 degree angle relative to the fuselage  15  will create a drag force of approximately 1586 lbs/sf to counteract the torque created by the rotation of the main rotor  45 . Drag may also be created when the helicopter  10  is hovering and loses thrust created by the tail rotor  55  due to, among other things, failure of the tail rotor  55  or loss of the tail rotor  55  entirely. In such instances, the helicopter  10  will be caused to spin in a direction opposite the rotation of the main rotor  45  as there is no longer a counteracting thrust generated by the tail rotor  55 . The rotation of the helicopter  10  will create airflow over the deflector  65  thereby creating drag, which will counteract at least some of the torque created by the rotation of the main rotor  45 . 
     The initial position of the deflector  65  on deployment can be predetermined by a manufacturer or may automatically be controlled by an airspeed indicator, increasing or decreasing the angle of the deflector  65  based on the airspeed of the helicopter  10 . The initial deployment of the deflector  65  will immediately start to correct helicopter yaw. After emergency yaw recovery, the position of the deflector  65  may be fine tuned to control yaw. For instance, in the present example, the actuator  70  is also operatively associated with the collective control or cyclic control (not shown) of the helicopter  10 . This allows the pilot to trim and fine tune yaw control by adjusting the angle of the deflector  65  with respect to the tail portion  35  of the fuselage  15  following the automatic correction of yaw upon the failure of the tail rotor  55 . Manual control can also be initiated by rudder pedals interlinked to the actuator  70 , as seen in the embodiment shown in  FIG. 4 . In  FIG. 4 , left and right pedals  1  and  2 , respectively, are typically used by the pilot to control the pitch of tail rotor  55  in normal flight, however, pedals  1  and  2  can be switched over and be used to control actuator  70 , upon tail rotor  55  failure. Pedals  1  and  2 , in this embodiment, are linked to actuator  70  such that operation of pedals  1  and  2  by the pilot controls deployment of deflector  65 . The linkage and control of the operation actuator  70  are commonly known for operation of controls on an aircraft, such as for example, hydraulic or electrical or combination thereof. Thus with tail rotor  55  not able to counter torque production of main rotor  45 , fuselage  15  begins to rotate in a clockwise direction. The pilot can depress left pedal  1  thereby activating actuator  70  to push deflector  65  outwardly away from the fuselage  15  to create drag and provide a counter force to the clockwise rotation of the fuselage  15 . Use of left and right pedals  1  and  2  can be employed by the pilot to appropriately trim the deployment of deflector  65  to create sufficient drag to, in turn, trim fuselage  15  into a desired stable orientation. While the actuator  70  in this example is activated by the tachometer  60 , it is understood that the actuator  70  may also be operatively associated with a directional gyro heading indicator, an autopilot or any other Nay Aid such that a failure in the tail rotor  55  is acknowledged and the deflector  65  is deployed. 
     The foregoing description of the various embodiments of the invention have been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The description was selected to best explain the principles of the invention and its practical application to enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention not be limited by the specification, but be defined by the claims set forth below.