What is retreating blade stall

The flare reduces the induced flow as some of the air is received from under the disc. When induced flow is reduced, the AOA is increased as the resultant relative wind is influenced more by the forward movement and rotation of the blades, if other factors remain the same. Forward cyclic as an initial response also increases the problem. If the cause is low rotor rpm, then increase the rpm.

Helicopters with articulating rotors usually designs with three or more main rotor blades are subject to ground resonance, a destructive vibration phenomenon that occurs at certain rotor speeds when the helicopter is on the ground.

This condition can cause a helicopter to self-destruct in a matter of seconds. If the rpm is low, the only corrective action to stop ground resonance is to close the throttle immediately and fully lower the collective to place the blades in low pitch. If the rpm is in the normal operating range, fly the helicopter off the ground, and allow the blades to rephase themselves automatically.

Then, make a normal touchdown. If a pilot lifts off and allows the helicopter to firmly re-contact the surface before the blades are realigned, a second shock could move the blades again and aggravate the already unbalanced condition.

For antitorque control, see tail rotor. Helicopter rotor The rotor head of a Sikorsky S 92 A helicopter main rotor or rotor system is a type of fan that is used to generate both the aerodynamic … Wikipedia. Mil Mi-X1 — is a high speed helicopter being proposed by Mil of Russia. Its… … Wikipedia. Retreating blade stall. Retreating blade stall Retreating blade stall is a hazardous flight condition in helicopter s and other rotary wing aircraft , where the rotor blade rotating away from the direction of flight stalls.

Look at other dictionaries: retreating-blade stall — The stall of a helicopter rotor disc that occurs starting at the tip of the retreating blade. The individual angle of attack of the retreating blade becomes larger because the downward blade … Aviation dictionary retreating blade — The process of the rotor blade moving away from the relative airflow i.

See retreating blade stall … Aviation dictionary blade stall — As it refers to rotorcraft, it is the condition of the retreating rotor blade when in forward flight and when operating at an angle of attack greater than the maximum angle of lift. This occurs at high forward speeds and when settling with power … Aviation dictionary Dissymmetry of lift — in rotorcraft aerodynamics refers to an uneven amount of lift on opposite sides of the rotor disc. This configuration is a feature of… … Wikipedia Helicopter rotor — This article is about helicopter main rotor systems.

Dictionaries export , created on PHP,. Mark and share Search through all dictionaries Translate… Search Internet. The relative airflow over the advancing side is higher due to the forward speed of the helicopter, while the relative airflow on the retreating side is lower. However, the upwards movement of the blade reduces the angle of attack giving constant thrust from the blade. As it continues to rotate it experiences progressively less relative airflow and flaps down.

This increases the angle of attack, again balancing the thrust.