helicopters A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

the rotorhead is the part of the rotor assembly that joins the blades to the shaft, cyclic and

collective A collective is a group of entities that share or are motivated by at least one common issue or interest, or work together to achieve a common objective. Collectives can differ from cooperatives in that they are not necessarily focused upon an ...

mechanisms. It is sometimes referred to as the rotor "hub". The rotorhead is where the lift force from the rotor blades act. The rotorhead is connected to the main drive shaft via the jesus bolt, and houses several other components such as the

swash plate A swashplate, also known as slant disk, was invented by Anthony Michell in 1917. It is a mechanical engineering device used to translate the motion of a rotating shaft into reciprocating motion, or vice versa. The working principle is similar to c ...

, flight control linkages and fly-bars. The rotor hub is also where the

centre of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...

acts on the helicopter. Sikorsky S-92 rotor P1230176

Types

Rotorheads can be classified into 3 main types: * Articulated * Semi-Rigid * Rigid

Articulated Rotorhead

An articulated rotorhead system is one where the individual blades are free to flap, lag and change pitch. This is done by mounting the blades on flapping and lagging hinges and pitch change bearings.

Semi-Rigid

A semi-rigid rotorhead does not have individual flapping or drag hinges but provides for flapping and lag motion through gimbal mounting.W.Z. Stepniewski, C.N Keys, "Rotory-Wing Aerodynamics'', Dover, 1984 A common example of a semi-rigid rotor is a teetering rotorhead found on the Robinson family of helicopters. Robinson-Rotorhead

Rigid

A rigid rotorhead has no flapping or lag hinges but does have pitch change bearings. The flapping and lagging movement is accommodated by flexible sections (commonly elastomeric bearings) at the blade root or blade attachment. When using composite blades, the blades can also flex to provide a flapping motion.A main rotor head that has no facility fhir the rotor blade tio flap or drag. Benefits of rigid rotor system are: * Less control response lag * Reduced maintenance

References

{{Reflist Helicopter components