- The additional lift (or rotor thrust) obtained through air speed because of the increased efficiency of the rotor system, whether it is when transitioning from a hover into forward flight or when hovering in a wind. During a hover, the rotors are lifting in a downward-moving column of air; the lift increases as the helicopter starts moving forward out of the descending column of air it created while hovering. With an increase in forward speed to about 12 to 15 knots, the rotor becomes more efficient and produces a dramatic increase in the lift compared to while hovering.When hovering in calm conditions, a given induced flow passes at right angle to the rotor disk. In case of any wind, the induced flow perpendicular to the disk becomes smaller.The downward vortex is beginning to dissipate and induced flow down through the rear of rotor disk is more horizontal than at hover.At slow speeds the perpendicular flow is substantial, but as airspeed increases it lessens while the horizontal component increases. At high speeds, the horizontal flow component is very large and would only reduce if the disk inclination becomes greater.
Aviation dictionary. 2014.
Look at other dictionaries:
Translational lift — is the extra lift created/received when a helicopter s forward speed increases from the hover. It should be noted that if there is a steady wind (above 10 knots) a helicopter in the hover may already be in translational lift.It is created when… … Wikipedia
translational speed — That speed where translational lift is acquired and transverse flow occurs … Aviation dictionary
Vortex ring — A vortex ring, also called a toroidal vortex, is a region of rotating fluid moving through the same or different fluid where the flow pattern takes on a doughnut shape. The movement of the fluid is about the poloidal or circular axis of the… … Wikipedia
Helicopter — For other uses, see Helicopter (disambiguation). Helicopter An LAPD Bell 206 … Wikipedia
Settling with power — Settling with Power, also known as Vortex Ring State [cite book | title = Rotorcraft Flying Handbook | publisher = Skyhorse Publishing, Inc. | location = Washington | year = 2007 | isbn = 1 60239 060 6 | page = 1 13 ] , is a hazardous condition… … Wikipedia
Flap back — or blowback is a phenomenon affecting the rotor of a helicopter as it overcomes dissymmetry of lift through flapping. In forward flight, rotor blades experience more lift as they rotate forward. This increased lift is a result of an increased… … Wikipedia
Gyrodyne — This article is about a class of rotorcraft. For the company bearing the name, see Gyrodyne Company of America. Gyrodyne … Wikipedia
Energy — This article is about the scalar physical quantity. For other uses, see Energy (disambiguation). Energetic redirects here. For other uses, see Energetic (disambiguation) … Wikipedia
Insect wing — Original veins and wing posture of a dragonfly. Hoverflies hovering to mate … Wikipedia
Flight dynamics — is the science of air and space vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle s center of mass, known as pitch , roll and yaw… … Wikipedia