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Aviation Info

The Rotor Blade Design

  • Relese Date:2016-01-29
  • Source:NASC

The helicopter’s rotor blades have long and narrow rotor blades that perform the same function as an aircraft’s wing. Rotor blades often reduce the lift force of wingtip to minimize resistance produced by the wingtip turbine. Rotor blades are composed by different materials, including aluminum, composite structure, steel or titanium and the abrasion resistance layer on the front edge.

Some of the wingtip of helicopter rotor blade is specially designed to reduce disturbance and noises, and to provide more effective flying experience.

Symmetric Wings or Non-Symmetric Wings

Symmetric wings are rather stable, helping to minimize the wing torque and flight burdens. Such stability is created by changing the angle of attack while keeping the center of the pressure unchanged. Today, the designer has adopted a thinner aircraft wing design and uses composite materials to obtain the needed rigidity. Besides, the upper and lower surfaces with different radian create a non-symmetric structure of the aircraft wing.

These aircraft wings are usually unstable during the flight. However, by changing the shape of aircraft wing, it is possible to create the same characteristics as the symmetric wings and make amendments accordingly. One of the reasons for non-symmetric rotor blades being unstable is that the pressure center changes according to the angle of attack. When the lift force of pressure center is in the center of gravity of rotor blades, it can easily cause tilt-up of rotor disc. Besides, the pressure center will move forward following the increase of angle of attack. If it it exceeds the center of gravity, the tilt angle of rotor disc will decrease. Because of this type of rotor blade, the rotor system can be operated in a higher acceleration.

Author: Tan Hsing-Chia, NASC, MOI.
References: Wikipedia