Graphical display for cueing helicopter main rotor aerodynamic braking

Abstract

The present invention relates to a graphical display for cueing helicopter main rotor aerodynamic braking. The graphical display comprises first indicia representing wind direction, second indicia representing main rotor roll control, third indicia representing main rotor pitch control, and fourth indicia representing a margin from main rotor flapping limit. The display cues a pilot with the proper direction in which to orient a rotor disk without exceeding main rotor flapping structural limitations.

1 . A display for cueing main rotor aerodynamic braking comprising: 
 first indicia representing wind direction;    second indicia representing main rotor roll control;    third indicia representing main rotor pitch control; and    fourth indicia representing a margin from main rotor flapping limit.    
   
   
       2 . A display according to  claim 1 , wherein said first indicia moves about a circle having a center at a fixed distance from said center.  
   
   
       3 . A display according to  claim 1 , wherein said second indicia comprises a roll bar and said third indicia comprises a pitch bar which intersects said roll bar.  
   
   
       4 . A display according to  claim 1 , wherein said fourth indicia comprises a circle.  
   
   
       5 . A display according to  claim 1 , further comprising a fifth indicia representative of collective pointer and a sixth indicia representative of an ideal collective position.  
   
   
       6 . A display according to  claim 5 , further comprising a digital indicator for cueing current rotor speed.  
   
   
       7 . A display according to  claim 5 , further comprising a seventh indicia representative of true rotor flapping limit.  
   
   
       8 . A system for assisting a pilot in aerodynamically braking a main rotor during an aircraft shutdown procedure comprising a plurality of sensors for sensing a plurality of aircraft parameters, a processor for processing said sensed aircraft parameters and means for cueing the pilot with the proper direction in which to orient a rotor disk without exceeding main rotor flapping shaft structural limitations.  
   
   
       9 . A system according to  claim 8 , wherein said cueing means comprises a graphics generator and a display.  
   
   
       10 . A system according to  claim 9 , wherein said sensors include means for sensing wind direction and said display depicts said wind direction using a vector symbol.  
   
   
       11 . A system according to  claim 10 , wherein said vector symbol rotates around a center of a circle according to said wind direction at a fixed radius from the center of the circle.  
   
   
       12 . A system according to  claim 9 , wherein said display includes a first circle representing a 10% margin from a main rotor flapping limit and a second circle representing a true rotor flapping limit based on a shaft bending Do-Not-Exceed value.  
   
   
       13 . A system according to  claim 9 , wherein said display includes a pitch bar, a roll bar, and a symbol depict a collective pointer to indicate current longitudinal, lateral cyclic and collective pitch control position.  
   
   
       14 . A system according to  claim 13 , wherein a vector sum is displayed as an intersection of the pitch bar and the roll bar, which sum corresponds to a given magnitude of flapping.  
   
   
       15 . A system according to  claim 9 , wherein said display includes a fixed pointer symbol depicting an ideal collective control position and a digital indicator for cueing current rotor speed.  
   
   
       16 . A method for assisting a pilot in aerodynamically braking a main rotor during an aircraft shutdown procedure, said method comprising the steps of: 
 providing a display having crossbars representative of longitudinal and lateral cyclic control position and a symbol representative of wind direction vector; and    overlaying said crossbars with said wind direction vector so as to orient a rotor disk such that a freestream air inflow angle is down through the rotor.    
   
   
       17 . A method according to  claim 16 , further comprising using cockpit control devices for controlling main rotor thrust control in accordance with cues presented by said display.