Coaxial rotorcraft control system

Abstract

A control system for a coaxial rotorcraft comprises a coaxial rotor set, further comprising an upper rotor actuated by a first drive shaft and a lower rotor actuated by a second drive shaft, the lower rotor having a direction of rotation counter to a direction of rotation of the upper rotor. A collective blade pitch control is configured to: collectively control pitch of only one of the upper rotor and the lower rotor and not another of the upper rotor and the lower rotor; and create an unbalanced torque force which acts on the rotorcraft and which enables a yaw attitude control input through said collective blade pitch control.

1 . A control system for a coaxial rotorcraft, comprising: 
 a coaxial rotor set, further comprising an upper rotor actuated by a first drive shaft and a lower rotor actuated by a second drive shaft, the lower rotor having a direction of rotation counter to a direction of rotation of the upper rotor;    collective blade pitch control, configured to: 
 collectively control pitch of only one of the upper rotor and the lower rotor and not another of the upper rotor and the lower rotor; and  
 create an unbalanced torque force which acts on the rotorcraft and which enables a yaw attitude control input through said collective blade pitch control.  
   
   
   
       2 . A control system as set forth in  claim 1 , wherein the collective blade pitch control collectively controls pitch of only the upper rotor.  
   
   
       3 . A control system as set forth in  claim 2 , further comprising a control link which is disposed within a drive shaft.  
   
   
       4 . A control system as set forth in  claim 1 , wherein the collective blade pitch control collectively controls pitch of only the lower rotor.  
   
   
       5 . A control system as set forth in  claim 4 , wherein cyclic pitch control is also provided on the lower rotor.  
   
   
       6 . A control system as set forth in  claim 1 , further comprising cyclic pitch control provided on at least one of the upper rotor and the lower rotor.  
   
   
       7 . A control system as set forth in  claim 6 , wherein cyclic pitch control is provided on the only one of the upper rotor and the lower rotor.  
   
   
       8 . A control system as set forth in  claim 7 , wherein both collective and cyclic control is provided on the upper rotor.  
   
   
       9 . A control system as set forth in  claim 6 , wherein cyclic blade pitch control is provided in both the upper rotor and the lower rotor of the coaxial rotor set.  
   
   
       10 . A control system for a coaxial rotorcraft, comprising: 
 a coaxial rotor set, further comprising an upper rotor and a lower rotor, the upper rotor having a direction of rotation counter to a direction of rotation of the lower rotor;    cyclic blade pitch control configured to cyclically control blade pitch of at least one of the upper rotor and the lower rotor;    collective blade pitch control, which provides a different change in blade pitch to one of the upper rotor and the lower rotor than that provided to the other of the upper rotor and the lower rotor, thereby enabling a differential torque providing yaw attitude control.    
   
   
       11 . A control system as set forth in  claim 10 , wherein the upper rotor and the lower rotor are essentially the same diameter.  
   
   
       12 . A control system as set forth in  claim 11 , configured to provide collective blade pitch control of the upper rotor.  
   
   
       13 . A control system as set forth in  claim 11 , configured to provide collective blade pitch control of the lower rotor.  
   
   
       14 . A control system as set forth in  claim 3 , wherein cyclic pitch control is also provided on the lower rotor.  
   
   
       15 . A control system as set forth in  claim 11 , wherein cyclic pitch control is provided on the same rotor as the collective blade pitch control.  
   
   
       16 . A control system as set forth in  claim 15 , wherein both collective and cyclic control are provided on the upper rotor.  
   
   
       17 . A control system as set forth in  claim 15 , wherein both collective and cyclic control are provided on the lower rotor.  
   
   
       18 . A control system as set forth in  claim 11 , wherein cyclic blade pitch control is provided on both of the upper rotor and the lower rotor of the coaxial rotor set.  
   
   
       19 . A control system for a coaxial rotorcraft, comprising: 
 a coaxial rotor set including an upper rotor and a lower rotor, said rotors being essentially the same size and having directions of rotation counter to each other    a collective blade pitch control configured to collectively control the blade pitch of one of said rotors and not collectively control the blade pitch of the other of said rotors, whereby an unbalanced torque force can be created which acts on the rotorcraft;    a cyclic blade pitch control configured to provide cyclic control of one of said rotors but not the other of said rotors;    whereby pitch, roll and yaw attitude control inputs can be made to the rotorcraft.    
   
   
       20 . A control system as set forth in  claim 19 , wherein the collective blade pitch control and the cyclic blade pitch control are on the same rotor of the coaxial rotor set.