![]() Indicated airspeed of an aircraft, corrected for installation and instrumentation errors. The complete wood, metal or composite structure of an airfoil.Ī helicopter’s gross weight divided by the total area of its main rotor blades, expressing the load supported by the blades. Sufficient lift is generally provided to allow controlled descent and safe landing.Ī straight line, real or imaginary, that describes a center of rotation, as of the rotor disc. Spinning of the main rotor by airflow over the blades during conditions of power off or power failuer. ![]() ![]() Though the complete explanation is quite lengthy, basically the pilot lowers the collective control and puts the main rotor blade pitch into a negative angle to maintain rotor RPM during decent before feathering out (pulling the collective back up) to complete a touch down/landing. Usually the helicopter would have to be within a predefined (by manufacturer) height/velocity atittude to be successful. The action where by a pilot puts a helicopter into a controlled decent without the aid of an engine. The ratio of a rotor blade’s span to its chord. Varying the pitch of this rotor provides directional control of the fuselage.Ī rotor whose blades are pivoted for flapping, dragging and pitch change.Īir Speed Indicator an instrument used for measuring speed relative to airflow, not relative the ground. ![]() Its sideward push or pull counteracts torque. Same as angle of attack sometimes defined as pitch.Ī small rotor mounted on one side of the tail boom of piston-engine helicopters having a single main rotor. Sometimes AOA can also refer to the angle between the longitudinal axis of an object (aircraft, enclosure, etc.) and the relative wind. The AOA and airspeed on an airfoil determine the life and drag of that airfoil.ĪOA may be positive or negative – positive refers to an AOA that creates an upward lift on the airfoil. The angle formed between the chord of a rotor blade and the relative wind the angle between the chord line of an airfoil (rotor blade) and the relative wind or airflow acting on that airfoil. Amplitude often refers to the maximum deviation of an oscillation. Airstream is normally depicted as a vector with amplitude and direction.Ī term borrowed from physics which is used to indicated the height of a curve or the maximum value of some variable under measurement. The amount of down-lift (or the incidence angle) of the horizontal stabilizer typically helps determine the “trimmed” airspeed. Typically, the horizontal stabilizer is configured with an amount of down-lift proportional to free airspeed so as to balance the center of gravity located forward of the thrust vector (of the rotor or a wing).Īs airspeed decreases below the “trimmed” airspeed, the down-lift of the horizontal stabilizer would also decrease, allowing the nose to lower and restore airspeed to the initial “trimmed” airspeed. The tendency of an aircraft to self-restore airspeed to the “trimmed” airspeed upon an airspeed disturbance. Typically, in discussions about rotorcraft, the “airframe” refers to the entire helicopter – less the rotors. The frame itself, often made of tubes, or the entire fuselage. The term “airfoil” also is often used to refer to the actual airfoil or lifting surface itself. The profile of a rotor blade (or wing) that would be present if the blade was sliced from the leading edge to the trailing edge. An aerodynamic shape is one that allows air to flow smoothly.Ī rotor blade specifically, a rotor blade defined by it’s surface curvature or outline, as viewed in cross section, and designed to provide lift. Relating to the flow of air around a body and that body’s reaction to that flow. The rotorblade that is moving forward through 180° in the direction of flight and opposite to the relative wind. ExpressionĪ change in velocity a change in either speed or direction or both. Aviation has it’s own particular terminology that can differ greatly from common english dictionary terms. The following are helicopter terms and definitions as pertaining to aviation, and helicopters or rotorcraft in particular. Helicopter Terms, Definitions & Expressions
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