ConingConingConingConing

As the helicopter develops lift during takeoff and flight, theAs the helicopter develops lift during takeoff and flight, thethe blade tips rise above the straight-out position and assumethe blade tips rise above the straight-out position and assumea coned position.a coned position.

As the helicopter develops lift during takeoff and flight, theAs the helicopter develops lift during takeoff and flight, thethe blade tips rise above the straight-out position and assumethe blade tips rise above the straight-out position and assumea coned position.a coned position.

Primary forces involved:Primary forces involved:Primary forces involved:Primary forces involved:

Centrifugal Force: Centrifugal Force: TThe force which tends to make rotating bodies he force which tends to make rotating bodies move away from the center of rotationmove away from the center of rotationCentrifugal force adds rigidity to the rotor blade, causing it to assume Centrifugal force adds rigidity to the rotor blade, causing it to assume a straight-out positiona straight-out position

Centrifugal Force: Centrifugal Force: TThe force which tends to make rotating bodies he force which tends to make rotating bodies move away from the center of rotationmove away from the center of rotationCentrifugal force adds rigidity to the rotor blade, causing it to assume Centrifugal force adds rigidity to the rotor blade, causing it to assume a straight-out positiona straight-out position

Lift: Lift: As the collective is increased and lift develops, the blades respond byAs the collective is increased and lift develops, the blades respond byrising above the straight-out positionrising above the straight-out positionLift: Lift: As the collective is increased and lift develops, the blades respond byAs the collective is increased and lift develops, the blades respond byrising above the straight-out positionrising above the straight-out position

ConingConingConingConingResultant: The combined effects of centrifugal force and liftResultant: The combined effects of centrifugal force and liftcause the blades to assume a coned position.cause the blades to assume a coned position.The angle between the straight-out position and the path The angle between the straight-out position and the path flown by the blades is the coning angle. flown by the blades is the coning angle. Some amount of coning is normal, however, excessive coningSome amount of coning is normal, however, excessive coningcan create problemscan create problems

Resultant: The combined effects of centrifugal force and liftResultant: The combined effects of centrifugal force and liftcause the blades to assume a coned position.cause the blades to assume a coned position.The angle between the straight-out position and the path The angle between the straight-out position and the path flown by the blades is the coning angle. flown by the blades is the coning angle. Some amount of coning is normal, however, excessive coningSome amount of coning is normal, however, excessive coningcan create problemscan create problems

Centrifugal ForceCentrifugal ForceCentrifugal ForceCentrifugal Force

LiftLiftLiftLiftResultantResultantResultantResultant

Causes of excessive coningCauses of excessive coningCauses of excessive coningCauses of excessive coning

•Low rotor RPM = Loss of centrifugal forceLow rotor RPM = Loss of centrifugal force

•High gross weight = More lift requiredHigh gross weight = More lift required

•High “G” maneuvers = More lift requiredHigh “G” maneuvers = More lift required

•Turbulence = Updrafts increase angle of attack, Turbulence = Updrafts increase angle of attack,

which increases coefficient of lift which increases liftwhich increases coefficient of lift which increases lift

•Low rotor RPM = Loss of centrifugal forceLow rotor RPM = Loss of centrifugal force

•High gross weight = More lift requiredHigh gross weight = More lift required

•High “G” maneuvers = More lift requiredHigh “G” maneuvers = More lift required

•Turbulence = Updrafts increase angle of attack, Turbulence = Updrafts increase angle of attack,

which increases coefficient of lift which increases liftwhich increases coefficient of lift which increases lift

Centrifugal ForceCentrifugal ForceCentrifugal ForceCentrifugal Force

LiftLiftLiftLift

Resultant or effective lifting areaResultant or effective lifting area

Effects of excessive coningEffects of excessive coningEffects of excessive coningEffects of excessive coning

•Decreased rotor area and useful liftDecreased rotor area and useful lift

•Stress on blades and blade rootsStress on blades and blade roots

•Decreased rotor area and useful liftDecreased rotor area and useful lift

•Stress on blades and blade rootsStress on blades and blade roots