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During takeoff, ground effect can cause the aircraft to "float" while below the recommended climb speed. The pilot can then fly just above the runway while the aircraft accelerates in ground effect until a safe climb speed is reached. [2] For rotorcraft, ground effect results in less drag on the rotor during hovering close to the ground. At ...
Ground resonance is an imbalance in the rotation of a helicopter rotor when the blades become bunched up on one side of their rotational plane and cause an oscillation in phase with the frequency of the rocking of the helicopter on its landing gear.
In contrast to other tilt-rotor craft ... Hover ceiling in ground effect : 12,000 ft (3,700 m) Hover ceiling out of ground effect : 6,000 ft (1,800 m) See also
The development of rotor CFD has undergone three stages. Full-Potential Equations; Euler Equations; Navier–Stokes Equations (RANS, LES) The full-potential equations are based on the potential flow theory, but the result computed by this method is usually larger than the real one as it ignored the effect of wake.
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.
This effort was initially funded by NASA/AFDD and subsequently by Bell. An experimental investigation in helicopter mode with ground effect found that it was possible to reduce the download on the aircraft from 10% of the total thrust to an upload of 10% of the thrust. [5] A parallel Computational Fluid Dynamics (CFD) study confirmed these ...
The Kopp–Etchells effect is a sparkling ring or disk that is sometimes produced by rotary-wing aircraft when operating in sandy conditions, particularly near the ground at night. The name was coined by photographer Michael Yon to honor two soldiers who were killed in combat; Benjamin Kopp, a US Army Ranger, and Joseph Etchells, a British soldier.
A ground effect vehicle (GEV) flies close to the terrain, making use of the ground effect – the interaction between the wings and the surface. Some GEVs are able to fly higher out of ground effect (OGE) when required – these are classed as powered fixed-wing aircraft. [29]