Coning

1
Coning
As the helicopter develops lift during takeoff
and flight, the the blade tips rise above the
straight-out position and assume a coned position.
Primary forces involved
Centrifugal Force The force which tends to make
rotating bodies move away from the center of
rotation Centrifugal force adds rigidity to the
rotor blade, causing it to assume a straight-out
position
Lift As the collective is increased and lift
develops, the blades respond by rising above the
straight-out position
2
Coning
Resultant The combined effects of centrifugal
force and lift cause the blades to assume a coned
position. The angle between the straight-out
position and the path flown by the blades is the
coning angle. Some amount of coning is normal,
however, excessive coning can create problems
Resultant
Lift
3
Causes of excessive coning

• Low rotor RPM Loss of centrifugal force
• High gross weight More lift required
• High G maneuvers More lift required
• Turbulence Updrafts increase angle of attack,
  which increases coefficient of lift which
  increases lift

4
Effects of excessive coning

• Decreased rotor area and useful lift
• Stress on blades and blade roots

Resultant or effective lifting area
Lift