Coning Angle

Coning angle is the angle formed between the plane of rotation of a helicopter rotor blade when it is producing lift and a line perpendicular to the rotor shaft. Also, Coning Angle is formed by the rotor blades with the tip path of the plane. (Tip Path Plane is the imaginary circular plane outlined by the rotor blade tips in making a cycle of rotation)

Coning happens primarily because of the variation of rotor thrust from root to tip.

The degree of the coning angle is determined by the relationship between the centrifugal force acting on the blades and the aerodynamic lift produced by the blades. From the figure, as the blade is rotating, there is a centrifugal force, which is throwing the blades outside. The force between upward and the centrifugal force when balanced results in one particular cone angle, which is called coning angle. An increase in helicopter weight results in an increase in coning angle.

There are upper limits and lower limits of coning angle. The upper limit will be defined by how much the engine can provide torque by which one can rotate the blades. The lower limit is defined by the rotor rpm which is a must to carry a specific amount of weight.

From the figure, we can see the upper limit by increased coning and the lower limit by lesser coning assuming both cases lift the same weight.

The lower coning angle has a higher tip path plane and the higher coning angle has a lesser tip path plane. Basically, the area is reduced when the coning angle is higher and vice versa. Thus, the power required similarly to compensate is going to be higher with the higher coning angle. The diameter of the higher coning angle will be lesser than the lower coning angle. A smaller disc diameter has less potential to produce lift.

Higher Coning Angle = Decrease in effective disc area = Decrease of total lift

Lower Coning Angle = Increase in effective disc area = Increase of total lift






The following project demonstrates the coning angle of helicopters with variable RPM. The project is interactive and the user can change the RPM and watch how it affects the Coning Angle. The following link will redirect you to the project page.

(For the mobile version, please go to the bottom of the page)

Helicopter Coning Angle on Scratch

Simple Coning Angle Simulation in Helicopters to understand the phenomenon of Coning Angles in Helicopter Rotors.

Press Up or Down Arrow to increase or decrease RPM.

The coning angle changes as per the RPM of the Rotor Blades.

The blades don't tilt so much in real life as shown in the project. This is a mere exaggeration.





Mobile Version of Helicopter Coning Angle on Scratch





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