Can the tail rotor produce thrust to the left?
The capability for tail rotors to produce thrust to the left (negative pitch angle) is necessary, because during autorotation the drag of the transmission tends to yaw the nose to the left, or in the same direction the main rotor is turning.
What is the main purpose of main tail rotor blade twist?
The main purpose of the tail rotor is to counteract the torque effect of the main rotor.
What force does tail rotor counteract?
A helicopter tail rotor serves two essential functions. It provides a counteracting force to the helicopter’s main rotor; without the sideways thrust produced by the tail rotor, the torque generated by the main rotor would spin the helicopter’s body in the opposite direction.
When a rotor blade is pitching or feathering it is?
Feathering the blade means changing the pitch angle of the blade. By changing the pitch angle of the blades you can control the thrust and direction of the main rotor disc.
Why do helicopters hang left skid low?
Helicopters usually hover left side low due to the tail rotor thrust being counteracted by the main rotor tilt. A nose low or high condition is generally caused by loading. Once stabilized, check the engine instruments and note the power required to hover.
What causes loss of tail rotor effectiveness?
Loss of tail-rotor effectiveness (LTE) occurs when the tail rotor of a helicopter is exposed to wind forces that prevent it from carrying out its function—that of cancelling the torque of the engine and transmission. Any low-airspeed high-power environment provides an opportunity for it to occur.
What is a tail rotor strike?
A tail-boom strike can happen as rotor rpm gets lower and the centrifugal force holding the rotor stiff drops. A helicopter that is starting up or shutting down in high winds or near another hovering helicopter is particularly vulnerable.
What is tail rotor thrust?
The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor’s rotation.
What is flapping and feathering?
Flapping, the vertical up/down movement of the blades, is not directly controlled. What a pilot controls is the blade feathering or pitch angle. Increasing feathering / pitch generally increases the aerodynamic forces on the blades, which changes the flapping.
What is rotor pitch?
propeller, the rotor has a pitch angle, which is the angle between the horizontal plane of rotation of the rotor disc and the chord line of the airfoil. The pilot uses the collective and cyclic pitch control (see below) to vary this pitch angle.
What is a turn around the nose in a helicopter?
It is simply a string attached to the nose or canopy of an aircraft so that it is visible to the pilot during flight. The string measures sideslip and offers a visual cue to the pilot in order to make yaw corrections.
Why would a helicopter hover in the same position?
Because both our atmosphere and the helicopter are moving at the same velocity, the atmosphere does not exert a force to the aircraft. A hovering helicopter stays in the same place relative to the surface unless it uses its flight control system to move its position relative to the ground.
How do you get rid of loss of tail rotor effectiveness?
Recovery. Recovery from an unexpected yaw movement is initiated by applying forward cyclic control to increase airspeed, and reducing power if at a safe altitude. If these measures are not effective, an entry into an autorotation may be necessary, applying full opposite rudder until rotation stops.
What happens if the tail rotor fails?
If the tail rotor fails in flight, engine torque can no longer be countered by the tail rotor, and uncontrolled spinning of the aircraft is a possibility. Most manufacturers call for an immediate autorotation. Some call for a running landing, instead.
How fast does a tail rotor spin?
Depending on the model and size of the helicopter, a helicopter’s blades, which are between 40-60ft long, spin from about 225 RPM to 500 RPM. Speed is determined by the power of the rotor and the length of the blade.
What is a Fenestron tail rotor?
A Fenestron (sometimes alternatively referred to as a fantail or a “fan-in-fin” arrangement) is an enclosed helicopter tail rotor that operates like a ducted fan. The term Fenestron is a trademark of multinational helicopter manufacturing consortium Airbus Helicopters (formerly known as Eurocopter).
How is tail rotor powered?
The tail rotor is powered by the helicopter’s main power plant, and rotates at a speed proportional to that of the main rotor.
What is rotor flapping?
Flapping is the vertical movement of a blade up or down to increase or decrease lift in order to compensate for dissymmetry of lift. To equalize lift across the rotor disc, the advancing blade flaps up and the retreating blade flaps down.
What causes retreating blade stall?
High weight, low rotor r.p.m., high density altitude, turbulence and/or steep, abrupt turns are all conducive to retreating blade stall at high forward airspeeds as they increase the blade pitch to generate more thrust and hence increase the angle of attack.
What is blade pitch angle?
Description. Blade pitch, often shortened to pitch, refers to the angle between the propeller blade chord line and the plane of rotation of the propeller. Blade pitch is most often described in terms of units of distance that the propeller would move forward in one rotation assuming that there was no slippage.
What do you mean by pitch angle?
propeller, the rotor has a pitch angle, which is the angle between the horizontal plane of rotation of the rotor disc and the chord line of the airfoil.
What are helicopter feet called?
Bear paws, floats and pontoons are also fairly common. Bear paws are attached to the skids and used for helicopters landing off airport on uneven, unstable and soft terrain helping with overall stability.
Why do military planes fly in circles?
The track they’re flying is called an orbit. They literally orbit a waypoint which other planes can request and fly to, to refuel. Also other type of military aircraft are using this type of flight-path as it fits to their assigned mission.
Why do helicopters fly at night?
Why Do Air Ambulance Helicopters Fly at Night? To ensure the fast response of medical attention is received many air ambulance helicopters will also fly at night. The helicopter really helps reduce the time it takes to reach patients in remote areas and allows for fast transfers between medical facilities.