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The effect of downwash from a hovering Sikorsky Seahawk is clearly visible on the surface of water below.. In aeronautics, downwash is the change in direction of air deflected by the aerodynamic action of an airfoil, wing, or helicopter rotor blade in motion, as part of the process of producing lift. [1]
The tail rotor is a smaller rotor mounted so that it rotates vertically or near-vertically at the end of the tail of a traditional single-rotor helicopter. The tail rotor's position and distance from the center of gravity allow it to develop thrust in a direction opposite that of the main rotor's rotation, thereby countering the torque effect ...
(This can be described as aerodynamic wash-in.) Winglets also promote a greater bending moment at the wing root, possibly necessitating a heavier wing structure. Installation of winglets may necessitate greater aerodynamic washout in order to provide the required resistance to spinning , or to optimise the spanwise lift distribution.
The signs of VRS are a vibration in the main rotor system [8] followed by an increasing sink rate and possibly a decrease of cyclic authority. [9]In single rotor helicopters, the vortex ring state is traditionally corrected by slightly lowering the collective to regain cyclic authority and using the cyclic control to apply lateral motion, often pitching the nose down to establish forward flight.
If a helicopter experiences a crosswind, the transverse flow effect will result in a pitching up or down instead of a roll. At higher airspeeds, more and more of the rotor disc will be in clean air and the lift differential will decrease, however transverse flow effect will be experienced to some extent across the whole flight envelope.
Download as PDF; Printable version; ... Helicopter height–velocity diagram; L. Lock number; Loss of tail-rotor effectiveness; P. Phase lag (rotorcraft) ...
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The Bell 407 is a four-blade, single-engine, civil utility helicopter. A derivative of the Bell 206L-4 LongRanger, the 407 uses the four-blade, soft-in-plane design rotor with composite hub developed for the United States Army's OH-58D Kiowa Warrior instead of the two-blade, semi-rigid, teetering rotor of the 206L-4.