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[1] [2] Unlike fixed-wing aircraft, of which the stall occurs at relatively low flight speed, the dynamic stall on a helicopter rotor emerges at high airspeeds or/and during manoeuvres with high load factors of helicopters, when the angle of attack(AOA) of blade elements varies intensively due to time-dependent blade flapping, cyclic pitch and ...
In particular, it limits the maximum forward speed of the aircraft. Two main issues restrict the speed of rotorcraft: [11] [4] [19] [12] Retreating blade stall. As forward speed of the helicopter increases, the airflow over the retreating blade becomes relatively slower, while the airflow over the advancing blade is relatively faster, creating ...
Retreating blade stall is a hazardous flight condition in helicopters and other rotary wing aircraft, where the retreating rotor blade has a lower relative blade speed, combined with an increased angle of attack, causing a stall and loss of lift. Retreating blade stall is the primary limiting factor of a helicopter's never exceed speed, V NE. [1]
However, when the helicopter starts to move forward its speed is added to the speed of the blades as they advance towards the front of the aircraft, and subtracted as they retreat. For instance, if the helicopter is flying forward at 100 km/h, the advancing blades see 300 + 100 km/h = 400 km/h, and for the retreating ones its 300 – 100 km/h ...
This situation, when not immediately recognized can cause a severe loss of aircraft controllability. Retreating blade stall is a factor determining the maximum forward speed of the helicopter, the never-exceed speed (V NE). At very high forward speeds, the advancing blade may go supersonic. This is another factor determining the never-exceed speed.
The Revised Code of Washington has a set of default speed limits for various types of roads. Rules of the Road: 25 mph is too fast. Is there a lower speed limit for residential alleys?
Autorotation is permitted mechanically because of both a freewheeling unit, which allows the main rotor to continue turning even if the engine is not running, as well as aerodynamic forces of relative wind maintaining rotor speed. It is the means by which a helicopter can land safely in the event of complete engine failure.
The fighter aircraft and helicopter responded to a civilian aircraft at 2:25 p.m. Saturday and escorted it to the ground. During the event, the aircraft dispensed flares in an attempt to draw ...