Optimum speed rotor

Abstract

A variable speed helicopter rotor system and method for operating such a system are provided which allow the helicopter rotor to be operated at an optimal angular velocity in revolutions per minute (RPM) minimizing the power required to turn the rotor and thereby resulting in helicopter performance efficiency improvements, reduction in noise, and improvements in rotor, helicopter transmission and engine life. The system and method provide for an increase in helicopter endurance and. The system and method also provide a substantial improvement in helicopter performance during take-off, hover and maneuver.

What is claimed is:  
     
         1 . A method for improving the efficiency of a helicopter for a specific flight condition, the helicopter comprising a rotor having radially extending blades and an engine for providing power to rotate the rotor at various RPM levels, the method comprising the steps of: 
 selecting a desired efficiency for a flight condition of a helicopter;    determining a rotor blade loading for the selected efficiency;    ascertaining an RPM value for achieving the determined blade loading; and    adjusting the RPM of the rotor to the ascertained RPM value.    
     
     
         2 . A method for improving the efficiency of a helicopter for a specific flight condition, the helicopter comprising a rotor having radially extending blades and an engine for providing power to rotate the rotor, wherein the rotor operates at a range of RPM levels ranging from 100% to less than 94% of the rotor maximum RPM level, the method comprising the steps of: 
 determining a rotor blade loading for improved efficiency for the flight condition, wherein said rotor blade loading is a function of in RPM;    ascertaining an RPM value for achieving the determined blade loading; and    adjusting the RPM of the rotor to the ascertained RPM value level.    
     
     
         3 . A method as recited in    claim 2    wherein the step of determining comprises the step of determining a range of blade loadings for improved efficiency for the flight condition, and wherein the step of ascertaining comprises the step of ascertaining an RPM range for achieving a blade loading within the determined range of blade loadings.  
     
     
         4 . A method for improving helicopter performance during a flight condition by decreasing fuel consumption, the method comprising the steps of: 
 providing a rotor driven to rotate by a powerplant consuming fuel;    operating the rotor for providing lift;    monitoring the fuel consumption; and    varying the rotor RPM to any level required for minimizing the powerplant fuel consumption for the flight condition while providing sufficient lift for the flight condition.    
     
     
         5 . A method as recited in    claim 4    wherein the rotor is a hingeless rotor.