直升機(jī)教員手冊(cè) Helicopter Instructor’s Handbook
時(shí)間：2014-11-10 08:35來(lái)源：FAA 作者：直升機(jī)翻譯 點(diǎn)擊：次
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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. Chord. An imaginary straight line between the leading and trailing edges of an airfoil section. Chordwise axis. A term used in reference to semirigid rotors describing the flapping or teetering axis of the rotor. Coaxial rotor. A rotor system utilizing two rotors turning in opposite directions on the same centerline. This system is used to eliminated the need for a tail rotor. Collective pitch control. The control for changing the pitch of all the rotor blades in the main rotor system equally and simultaneously and, consequently, the amount of lift or thrust being generated. Coning. See blade coning. Coriolis effect. The tendency of a rotor blade to increase or decrease its velocity in its plane of rotation when the center of mass moves closer or further from the axis of rotation. Cyclic feathering. The mechanical change of the angle of incidence, or pitch, of individual rotor blades independent of other blades in the system. Cyclic pitch control. The control for changing the pitch of each rotor blade individually as it rotates through one cycle to govern the tilt of the rotor disk and, consequently, the direction and velocity of horizontal movement. Delta hinge. A flapping hinge with an axis that is skewed so that the flapping motion introduces a component of feathering that results in a restoring force in the flapwise direction. Density altitude. Pressure altitude corrected for nonstandard temperature variations. Deviation. A compass error caused by magnetic disturbances from the electrical and metal components in the aircraft. The correction for this error is displayed on a compass correction card place near the magnetic compass of the aircraft. Direct control. The ability to maneuver a rotorcraft by tilting the rotor disk and changing the pitch of the rotor blades. Direct shaft turbine. A shaft turbine engine in which the compressor and power section are mounted on a common driveshaft. Disk area. The area swept by the blades of the rotor. It is a circle with its center at the hub and has a radius of one blade length. Disk loading. The total helicopter weight divided by the rotor disk area. Dissymmetry of lift. The unequal lift across the rotor disk resulting from the difference in the velocity of air over the advancing blade half and retreating blade half of the rotor disk area. Drag. An aerodynamic force on a body acting parallel and opposite to the relative wind. Dual rotor. A rotor system utilizing two main rotors. Dynamic rollover. The tendency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point. Feathering. The action that changes the pitch angle of the rotor blades by rotating them around their feathering (spanwise) axis. Feathering axis. The axis about which the pitch angle of a rotor blade is varied, sometimes referred to as the spanwise axis. Feedback. The transmittal of forces, which are initiated by aerodynamic action on rotor blades, to the cockpit controls. Flapping hinge. The hinge that permits the rotor blade to flap and thus balance the lift generated by the advancing and retreating blades. Flapping. The vertical movement of a blade about a flapping hinge. Flare. A maneuver accomplished prior to landing to slow a rotorcraft. Free turbine. A turboshaft engine with no physical connection between the compressor and power output shaft. Freewheeling unit. A component of the transmission or power train that automatically disconnects the main rotor from the engine when the engine stops or slows below the equivalent rotor rpm. Fully articulated rotor system. See articulated rotor system. Gravity. See weight. Gross weight. The sum of the basic empty weight and useful load. Ground effect. A usually beneficial influence on rotorcraft performance that occurs while flying close to the ground (within one rotor diameter). It results from a reduction in upwash, downwash, and blade-tip vortices, which provide a corresponding decrease in induced drag. Ground resonance. Self-excited vibration occurring whenever the frequency of oscillation of the blades about the lead-lag axis of an articulated rotor becomes the same as the natural frequency of the fuselage. Gyroscopic procession. An inherent quality of rotating bodies, which causes an applied force to be manifested 90° in the direction of rotation from the point where the force is applied. Human factors. The study of how people interact with their environment. In the case of general aviation, it is the study of how pilot performance is influenced by such issues as the design of cockpits, the function of the organs of the body, the effects of emotions, and the interaction and communication with other participants in the aviation community, such as other crew members and air traffic control personnel. Hunting. Movement of a blade with respect to the other blades in the plane of rotation, sometimes called leading or “lagging.” Inertia. The property of matter by which it will remain at rest or in a state of uniform motion in the same direction unless acted upon by some external force. In-ground-effect (IGE) hover. A hover close to the surface (usually less than one rotor diameter distance above the surface) under the influence of ground effect. Induced drag. That part of the total drag that is created by the production of lift. Induced flow. The component of air flowing vertically through the rotor system resulting from the production of lift. Isogonic line. Lines on charts that connect points of equal magnetic variation. Knot. A unit of speed equal to one nautical mile per hour. LDMAX. The maximum ratio between total lift (L) and total drag (D). This point provides the best glide speed. Any deviation from the best glide speed increases drag and reduces the distance you can glide. |
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